Johnson Matthey Technology Review · UK ISSN 0032-1400 PLATINUM METALS REVIEW A Quarterly Survey of...

UK ISSN 0032-1400

PLATINUM METALS REVIEW A Quarterly Survey of Research on the Platinum Metals and

of Developments in their Application in Industry www.matthey.com and www.platinum.matthey.com

VOL. 45 APRIL 2001 NO. 2

Contents The U.S. Motor Vehicle Emission Control Programme

By Bruce I. Bertelsen

Rhodium Bicentenary Competition

Biomimetic Chiral Rhodium Catalysis

Catalytic Polymerisation of Cycloolehs Reviewed by Manfred Bochmann

Ruthenium in Medicine: Current Clinical Uses and Future Prospects By Claire S. Allardyce and Paul J. Dyson

Thiazepinones Synthesis with Rhodium

New European Autocatalyst Plant at Royston By Gavin Young

Exhaust Emissions Control Developments By M. V. Twigg

High Temperature Mechanical Properties of the Platinum Group Metals

By Jiirgen Merker, David Lupton, Michael Topfer and Harald Knake

Ruthenium-Initiated Star Polymers

Commercial Heterogeneous Catalysis Reviewed by M. Hayes

Alloy Structures of the Ti-Ni-Ru System in the Ti-TNi-TiRu Composition Range

By E. L. Semenova and N. Yu. Krendelsberger

Ruthenium-Manganese Attificial Photosynthesis Systems

The Seventh Grove Fuel Cell Symposium

Alfa Aesar All-In-One Catalogue

Abstracts

New Patents

50

59

59

60

62

69

70

71

74

82

83

84

91

91

91

92

97

Communications should be addressed to: The Editor, Susan V. Ashton, Platinum Metals Review, [email protected] Johnson Matthey Public Limited Company, Hatton Garden, London EC1N 8EE

The U.S. Motor Vehicle Emission Control Programme BUILDING ON PAST SUCCESSES TO MEET FUTURE CHALLENGES

By Bruce I. Bertelsen Manufacturers of Emission Controls Association, 1660 L Street, NW, Suite 1100, Washington, DC 20036, U S A

The United States motor vehicle emission control programme is noted for its pioneering role and success in limiting exhaust pollution, utilising the three-way catalvst, cleaner,fuels, improved engine design and calibration strategies. The progressive lowering of the emission limits by technology-forcing legislation via the agencies of the U S . Environmental Protection Agency and the California .state legislature has resulted in cleaner air: Here, progress to date and future intentions for emissiotzs from gasoline and diesel vehicles are discussed.

The United States motor vehicle emission control programme has rightly earned the reputation as one of the world’s great environmental success stories. Today, emissions of harmful pollutants from new cars are a small fraction of those emitted from cars made in the 196Os, and lead, one of the most insidious pollutants, has been completely eliminated from gasoline. As a result, the ambient air in the US. is much cleaner than it was 30 years ago even though the U.S. resident population has increased by 33 per cent, vehicle miles travelled have increased by 140 per cent and the gross domestic product has increased by 147 per cent during the same period (1). Of equal importance, the strategies and technologies achieving these significant pollution reductions have contributed to a dramatic increase in fuel economy and have allowed automakers to continue to provide high- performance vehicles to the driving public.

However, despite the enormous progress that has been made in reducing motor vehicle emissions, highway vehicles continue to be one of the primary contributors to air pollution in the U.S. Further, non-road vehicles and equipment account for an increasing contribution to both diesel particulate matter (Pv and oxides of nitrogen (NOx) (2). According to the U.S. Environmental Protection Agency (EPA), over 60 million people in the U.S. still live in areas with unhealthy air (1).

To meet these air quality challenges, the US. EPA, over the past several years, has undertaken

an unprecedented regulatory initiative to: 0 W e r reduce emissions from on-road light- and heavy-duty vehicles; 0 establish new control programmes for a growing variety of off-road vehicles and equipment; and 0 limit the allowable levels of sulfur in fuel.

Catalyst-based control technology, which has played a critical role in the past successes of the U.S. programme, will play a major role in meeting these future challenges.

Background In 1955, smog in Los Angeles was worse than it

is in Mexico City today. By the late 1950s, it had become clear that motor vehicles were the primary culprits. In response, Congress passed the Clean Air Act Amendments of 1970 that created the US. motor vehicle emission control programme. This Act imposed tough, technology-forcing emission standards and a supporting programme to ensure compliance (3).

Congress required over 90 per cent reduction in hydrocarbons (HC) and carbon monoxide (CO) emissions over uncontrolled levels by the 1975 model year, and an approximately 90 per cent reduction of NOx by the 1976 model year. At that time the technology needed to meet those standards did not exist, but Congress knew that without the ‘incentive’ of statutory requirements, the automobile industry would not develop the technology needed to clean up vehicle emissions.

P(atinum Met& Rev., 2001,45, (2), 5C59 50

Table I

Automobile Emission Standards (grams per mile, g/mi)

Model year

1960 1970 1975 1980 1981 1983 1994 2001 2004

Hydrocarbons Carbon monoxide

10.6‘ 84.0’ 4.1 34.0 1.5 15.0 0.41 7.0 0.41 3.43 0.41 3.4 O X 4 3.4 0.1 255 3.4 0.og6 1.76

Nitrogen oxides

1. EPA-c.~tirnaredpre-coittrolfiKure 2. At.first control .f h!dmcarboris and carbon monoxide cuused an increase in nitrogen o.ride.s. 3. Waived for certain models thut could nor economicu[lv meet this stundud. They mer rhe 7.0 standard instead. 4. Noii-methane hydrocarbons 5. Corporate average 6. Phuse-in 2004-2007: corpurure uveruge

Thus, Congress adopted performance-based, technology-forcing standards and recognised that lead in gasoline impeded the effectiveness of promising technologies, such as the catalytic converter. Thus, Congress paved the way for the introduction of unleaded gasoline.

In the early 1970s, the original deadlines for the emission standards were postponed several times, less stringent interim standards were set, and the original goal for NOx control was modified. Nevertheless, emission control technologies evolved at a much faster pace than would have occurred without the ‘technology-forcing’ provi- sions of the 1970 law.

In 1977, Congress fine tuned the law and mandated that all gasoline-powered cars must meet stringent standards by the 1983 model year (4). In 1990, Congress further tightened the standards beginning with the 1994 model year (the ‘Tier 1 standards? and gave the EPA the authority to tighten the hght-duty vehicle standards beginning in 2004 (5). In 1999, the EPA adopted the Tier 2 standards’ that require more substantial reductions in emissions from automobiles, pick-up trucks, vans and sport-utility vehicles (SWs) to be phased-in between 2004 and 2009 (6). Table I shows the progress in establishing increasingly stringent emission standards for automobiles.

The 1977 and 1990 Clean Air Act Amendments

4.1’ 5.0’ 3.1 2.0 1 .o 1 .o 0.4 0.2 0.076

also targeted hght-duty trucks, large trucks and buses for emission control. Furthermore, the 1990 Amendments called for the first time upon the EPA to address emissions from off-road vehicles and equipment. In response to the Clean Air Act mandate, the EPA is implementing a comprehensive programme to address emissions from on-road trucks and buses and a wide variety of off- road vehicles and equipment.

Over the past 25 years, the EPA has effectively designed, implemented and enforced the motor vehicle emission control programme to achieve the clean air objectives mandated by Congress. The State of California has also played a vital role in helping to shape the evolution of the U.S. motor vehicle emission control programme. Indeed, California’s motor vehicle emission control programme pre-dates the national programme and standards initially adopted by California have often become the U.S. requirements.

Future U.S. Emission Standards and Fuel Quality Requirements (a) Passenger Cars, Light-Duty Trucks and Medium-Duty Passenger Vehicles

On 10th February 2000, the EPA published new, more stringent standards (‘the Tier 2 standards? for light-duty vehicles (passenger cars), hght-duty trucks up to 8500 lbs gross vehicle

PLztintm Metab REV., 2001,45, (2) 51

a. 0.60 NOx cap applies to balance of LDTJdLDT4s. respectively, during the 2004-2006 phase-in years. b. Alternative phase-in pmvisians allow manufacturers to deviate from the 2S/SOi7S% 20042006 arid 50% 2008 phase-in requirements

and provide credit for phasing in some vehicles during one or more of these model yeurs. c. Required only for manufacturers electing to use optional NMOG valuesjhr L D n s or LDT4s and MDPVflexibilities during the

applicable interim programme and.for vehicles whose model !ear commeiwes 011 or ufrer the fourth anniversary date of the signature of this rule. See discussion in text.

d. MDPV.s, HLDTs. and MDPVs must be averaged together: e. Diesels mav be engine-certified through the 2007 model year

weight r a w (GVWR), and medium-duty passenger vehicles (8501-10,000 lbs GVWR) to be phased in between 2004 and 2009 (6). The phase- in schedule for the Tier 2 standards is shown in Table I and the Tier 2 standards are shown in Table 11.

The Agency also established a requirement for all gasoline fuel sold in the U.S. to have a 30 ppm average (avg) sulfur level on an annual basis begir- ning in 2005 and a 80 ppm sulfur cap beginning in 2006 (6).

The Tier 2 standards require all gasoline and diesel passenger cars, hght-duty trucks and medium-duty passenger vehicles to meet the same stringent standards by 2009. The cornerstone of the Tier 2 programme is that manufacturers may choose to comply by certifying the mix of vehicles

corporate average meets the applicable interim or final NOx standard. Vehicle manufacturers are required to meet a corporate average 120,000 mile 0.07 NOx standard. Heavier light-duty trucks (called LDT3s and LDT4s) are given more time to meet the corporate average (avg) 0.07 grams per mile &/mi) NOx standard (100 per cent by 2009) compared to passenger cars and light-duty trucks (LDTls and LDT2s) (100 per cent by 2007). EPA has also included medium-duty passenger vehicles (< 10,000 Ibs GVWR) in the programme. Under the Tier 2 programme, there are eight emission standard bins (sins 1-8) for the Tier 2 standards, see Table 111. Two additional bins (sins 9-10) are available only during the interim period and will be eliminated before the final phase-in of the Tier 2 programme. An eleventh bin, shown in Table IV,

to different sets of standards or bins, as long as the is available only for MDPVs and expires in 2008.

Plrrtinwm Metah b., 2001,45, (2) 52

TableII

Tier 2 and Interim Non-Tier 2 Phase-In and Exhaust Averaging Sets(The shaded areas indicate averaging sets)

Bin # NOx NMOG co HCHO

10 0.6 0.1 5W0.230 4.2/6.4 0.018/0.027 9 0.3 0.090/0.180 4.2 0.01 8

0.20 0.15 0.10 0.07

1 0.04 0.03 0.02 0.00

PM Comments

0.08 a, b, c, d 0.06 a, b. e

0.125/0.156 0.090 0.090 0.090 0.070 ' 0.055 0.010 0.000

4.2 4.2 4.2 4.2 2.1 2.1 2.1 0.0

Full useful life (120,000 mile)

0.01 8 0.018 0.018 0.01 8 0.01 1 0.01 1 0.004 0.000

NOx NMOG co HCHO PM

0.9 0.28 7.3 0.032 0.12

0.02 0.02 0.01 0.01 0.01 0.01 0.01 0.00

b. f

a. Bin deleted at end of 2006 model year (2008 for HLDTS). b. The higher temporary NMOG. CO and HCHO values apply only to HLDTS and expire afer 2008. c. An additional temporary higher bin restricted to MDPVs is discussed below. d. Optional temporary NMOG standard of 0.280 g/mi applies for qualifying LDT4s and MDPVs only. e. Optional temporary NMOG standard of 0.130 g/mi applies for qualifying LDT2s only, see text. f: Higher temporary NMOG standard is deleted at end of 2008 model year

(b) On-Highway Heavy-Duty Engines The EPA has two separate rulemakings affect-

ing highway HDEs: Phase 1 directed at 2004 to 2006 HDEs and Phase 2 directed at 2007 and later model year HDEs.

can be met with currently available diesel fuel; Sets new, more stringent standards for all

heavy-duty Otto-cycle (for example gasoline- fuelled) engines and vehicles which wiU result in an approximate 75 per cent reduction in HC and

Phase 1 On 6th October 2000, EPA published its hnal

rule covering the technological feasibility hndmg for the previously adopted diesel HDE 2004 standards and new standards for gasoline-powered HDVs (7). The final rule:

Reaffms that the 2004 model year NMHC+NOx and PM standards (2.5 g/bhp-hr NOx+NMHC and 0.1 g/bhp-hr PM), origdly adopted in 1997, are technologically feasible and

NOx emissions from this category of vehicles; 0 Requires OBD systems for all heavy-duty vehicles and engines at or below 14,000 lbs GVWR and revises the OBD requirements for diesel hght-duty vehicles and trucks; and

Implements additional certification test procedures and associated standards for heavy-duty engines and vehicles to address the issue of off- cycle emissions begjnning in 2007.

The standards which will apply to gasoline- powered heavy-duty engines and vehicles are

I Table IV

Pkatirrnm Me,%& b., 2001,45, (2) 53

Table ill

Tier 2 Light-Duty Full Useful Life Exhaust Emission Standards (grams per mile, g/mi)

The above temporary bens expire in 2006 (for LDVs and ::DTs) and 2008 (for HLDTs)

8 7 6 5 43 2 1

Temporary Interim Exhaust Emission Standards Bin (Bin 11)for MDPVsa

a. Bin expires aater model year 2008

Table V

Phase 1 : NOx and HC Standards fo r Gasoline Vehicles

Gross Vehicle Weight (GVW)

8,500-10,000 pounds 10,001-14,000 pounds

14,001 pounds and above

NOx (g/mi) HC (glmi)

0.9 0.28 1 .o 0.33

1.0 g/bhp-hr (combined NOx and HC)

shown in Table V. The current NOx standard for both diesel and gasoline vehicles is 4.0 g/bhp-hr. The current HC standard for diesel is 1.3 g/bhp-hr and for gasoline is l.lg/bhp-hr.

Phae 2 On 21st December 2000, the EPA adopted

emission standards for 2007 and later model year highway heavy-duty engines and vehicles and established limits on the allowable levels of sulfur in diesel fuel (8). The regulations call for a 90 per cent reduction in PM and a 95 per cent reduction in NOx emissions from heavy-duty diesel engines compared to the standards currently applicable; aghter standards for gasoline-powered vehicles and a 97 per cent reduction in the allowable levels of sulfur in diesel fuel.

The EPA noted that these regulations are equivalent to removing 13 million of today’s trucks off the road. The emission standards for HDEs are shown in Table VI below. The rule will result in

Diesel NOx NMHC HCHO

NMHC HCHO

Gasoline NOx

Diesel PM

Gasoline PM

NOx and PM exhaust control technology being installed on every on-road HDE.

The final rule has several key elements: 0 A sulfur cap of 15 ppm beginning 1st June 2006 for diesel fuel sold for use in highway vehicles (20062009: 80 per cent and beginning in 2010 100 per cent); 0 A PM standard of 0.01 g/bhp-hr which would take effect with the 2007 model year; 0 A NOx standard of 0.2 g/bhp-hr and a

NMHC standard of 0.14 g/bhp-hr, to be phased in beginning with the 2007 model year with 100 per cent compliance by 2010; 0 Formaldehyde emission standards and new requirements for crankcase emissions on turbo- charged diesel engines; 0 Tighter standards for heavy-duty vehicles certified as complete vehicles; 0 Standards requiring reductions in evaporative emissions.

The emission standards for complete heavy-

Standard Phase-In by model year (g/bhp-hr) 2007 2008 2009 201 0

0.20 0.14 50% 50% 50% 100% 0.016

0.20 0.14 0% 50% 100% 100% 0.01 6

0.01 100%

0.01 0% 50% 100% 100%

Phtinum Met& Rev., 2001,45, (2) 54

Phase 2: Full Useful Life Heavy-Duty Engine Emission Standards and Phase-Ins

Table VI

GVWR

8,500-10,000 10,000-14,000

duty vehicles (HDVs) would be implemented on the same schedule as for engine standards and are shown in Table VII.

PM NOx NMHC

0.02 glmi 0.2 glmi 0.195 glmi 0.02 glmi 0.4 glmi 0.230 glmi

(c) Off-Road Vehicles and Equipment Off-road vehicles and equipment cover a wide

range of spark-ignition (Sl) and compression- ignition (Cl) applications including construction equipment, locomotives, industrial handling equipment, marine vessels and lawn, and garden equipment. Until the mid-l990s, these applications went largely unregulated. But in the late 1990s, the EPA adopted regulations to control emissions from recreation marine engines, locomotives, construction and similar off-road heavy-duty engines, and lawn and garden equipment. For the most part, these standards can be met without the use of exhaust emission control technology, such as the catalytic converter. However as the relative contribution to ambient pollution from these off-road mobile sources con- tinues to grow, EPA plans to require M e r reductions. Two examples are discussed below.

(i) Heav-Dag Of-Road Diesel Engines In 2001, EPA is expected to propose new PM

standards (referred to as the Tier 3 PM standards) for off-road diesel engines to take effect in the 2006-2008 timeframe which would be comparable to the 2004 on-road HDE PM standard (0.1 g/bhp-hr). EPA is also expected to propose even- tually that off-road engines meet emission standards comparable to the on-hlghway HDEs Phase 2 standards. These later standards (referred to as the Tier 4 standards) would requite the use of both NOx and PM exhaust emission control technology. An important component of the EPA’s planned clean-up of off-road HDEs is to reduce

the s u l f u i content in diesel fuel used in off-road applications (currently averaging - 3000 ppm). EPA may employ a two-phase requirement, first c a h g for a 500 pprn sul fur limit in 2006 and then a further reduction to a 15 ppm cap to be timed with implementation of the Tier 4 standards, which is anticipated in the 2010 timeframe.

(ii) OflRoad Spark-Igrtidon Engines > 25 Lip In 2001 EPA is planning to propose emission

standards for SI engines > 25 hp, used in industrial handling and similar applications. The standards would take effect around 2005 and will be met by the use of three-way catalyst technology.

California’s Continuing Lead in U.S. Motor Vehicle Emission Control

As part of the 1970 Clean Air Act Amendments, Congress gave the State of California the unique authority to implement its own motor vehicle emission control programme. Other states may adopt elements of the California programme, but they may not adopt their own programme. The California programme, originally established in the 1960s, has, over the past 30 years, served as the nation’s laboratory’ for prov- ing out new regulatoiy programmes and concepts as well as new technologies. For example, the tighter standards for NOx set in California in the 1970s resulted in the first introduction of the three-way catalyst and sophisticated engine controls, which allowed simultaneous control of the three gaseous pollutants emitted in automotive exhaust. More recently, California’s light-duty emission control programme, ‘Low Emission Vehicle programme (LEV and LEV 2), served as the model for the EPA’s Tier 2 standards. California also adopted regulations for a variety of

Phfinnm Metah Rev., 2001,45, (2) 55

Table VII

Phase 2: Emission Standards for HDVs

Table Vlll

ARB Planned Control Measures

Control measure Rule developed

On-Road Mobile Sources Lower New Engine Standards Retrofit Existing Engines HDV In-Use Compliance Programme Supplemental HDV Certification Procedures

Off-Road Mobile Sources Lower New Engine Standards Retrofit Existing Engines Diesel Pleasure Craft Standards HDE In-Use Compliance Programme

2001 2002 2003 2000

2002 2002 2002 2003

Stationary and Portable Engines Address New and Existing Engines

(emergencyktandby, prime, agriculture, and portable engines) 2002

Federal Action Required Locomotives NO bate set Commercial Marine Vessels No date set New Farm and Construction

Equipment < 175 hp No date set

New Vehicle Standards and Fuel Specifications 2000

off-road SI engines which have served as a model for standards later adopted by the EPA. Loow to the future, California is expected to

continue its leadership role. For example, in September 2000, California approved a comprehensive plan to reduce the total PM emissions from diesel-fuelled engines by 75 per cent in 2010 and by 85 per cent in 2020 (9). The California Air Resources Board (ARB) plan identifies diesel particulate filters as the principal technology expected to be used to reduce PM emissions from both existing and new diesel engines. Other strategies identified by ARB include fuel cells, electrification, alternative fuels, alternative diesel fuel formula- tions and additives, and engine modifications.

The ARB plan calls for cutting emissions by at least 85 per cent from up to 90 per cent of the existing on-road, off-road, and stationary engines, and by at least 90 per cent from new engines. The ARB plan recognises that control retrofit might

not be technically possible and cost-effective in every engine application and has committed to work with interested parties to insure a fair, cost- effective, and technically sound programme.

Over the next two to three years, the ARB staff will be developing 14 new control measures including four measures that will require the coop- eration and action of the US. EPA. The 14 control measures are summarised in Table WI . The control requirements will be phased in between 2006 and 2010.

Future Emission Standards in the U.S. Meeting Tier 2 by Passenger Cars, Light-Duty Trucks, and Medium-Duty Passenger Vehicles

As noted above, the technological solution to meeting the Tier 2 standards adopted by the EPA will be a systems approach, employing advances in engine technology, advanced catalyst technology and low sulfur fuel. EPA, in its h a l rule, stated that the type of control strategies likely to be employed included ongoing improvements in computer software, engine air/fuel controls, advances in catalyst designs and catalyst/system integration, increases in noble metal loadmg and other exhaust system/catalyst system improvements. Table M lists the types of engine/exhaust/ catalyst technology improvements and advancements that will likely be employed to meet the Tier 2 standards. For diesel-fuelled vehicles, EPA stated that exhaust control technology would probably be needed. For NOx emissions, EPA listed lean NOx catalysts, NOx adsorbers and selective catalytic reduction (SCR) as potential technologies. For PM control, EPA identified oxidation catalysts and PM filter technology. EPA stressed the importance of low sulfur fuel in enabling catalyst-based emission control technology to be optimised for maximised emission reductions.

Meeting Phase 1 and Phase 2 Standards by On-Road Heavy-Duty Diesel Engine

Engine manufacturers are expected to use a combination of engine modifications and EGR to meet the Phase 1 2004 standards. In some instances, an oxidation catalyst may be employed to control any increases in PM emissions resulting

Phtiinlrm Metah Rev., 2001, 45, (2) 56

Table IX

Advanced Engine/Exhaust/Emission Control Strategies for Gasoline-Powered Vehicles

Technology Advancements to be employed

Catalyst technology Layered washcoat and support materials with high thermal stability High cell density catalyst supports (substrates) Thin-walled (lower mass) catalyst supports Mounting materials with improved durability New catalyst support designs (e.g., hexagonal cell structure, contoured end cones) Thermally-insulated components

Electronic engine controls Higher idle speeds with engine spark retard Higher speed computer processors Model-based control algorithms Injectors with improved fuel atomisation Variable camhalve timing Electronic EGR Electronic throttle control CVT (continuously variable transmission)

Emission system sensors (control and diagnostics)

Linear oxygen sensors Planar oxygen sensors Fast response temperature sensors Combination NOx/02 sensor

Thermal management Air-gap manifolds, exhaust pipes, and converter shells offer low heat capacity and high heat insulation to improve converter warm-up and minimise outer surface temperatures

from the use of EGR to ensure that the engine meets the 0.1 g/bhp-h standard. To meet the expected Phase 2 heavy-duty engine standards, a systems approach will be required, which com- bines advanced engine technology and both NOx and PM exhaust control technologies. To enable the use and complete optimisation of the existing and emerging NOx and PM exhaust emission control technologies, very low sulfur diesel fuel will be needed. Diesel particulate filters or ‘traps’ will likely be used to meet the very stringent Phase 2 PM standards. NOx adsorber and SCR appear to be the lea- strategies to help meet the tough Phase 2 NOx standards.

Conclusion The U.S. Environmental Protection Agency is

in the process of establishmg very stnngent emission standards for virtually every category of motor vehicle. These standards, which will take effect in the 200&2010 timeframe, will require

substantial emission reductions over the levels currently required. Meeting these stringent standards present significant engineering challenges. The solution will be an engineered systems approach combining advanced engine designs, advanced catalyst-based control technologies, and low sulfur fuel. Engine, vehicle, and emission control manufacturers are workmg together to develop and optimise the needed technological solutions. The prospects for meeting these very stringent emissions levels, as reviewed here, appear to be e x d e n t

References 1

2

3

4

5

U.S. EPA, Latest Findlags on National Air Quality: 1999 Status and Trends, August 2000 US. EPA, National Air Pollutant Emission Trends, 900-1998, March 2000 “Clean Air Act Amendments of 1970” (PL 91-604, 1970) “Clean Air Act Amendments of 1977” (PL 95-95, 1977) “Clean Air Act Amendments of 1990” (PL 101-549, 1990)

Phhnwn Me& b., 2001,45, (2) 57

6 US. EPA, “Control of Air Pollution from New Motor Vehicles: Tier 2 Motor Vehicle Emission Standards and Gasoline Sulfur Control Requirements”, 40 CFR Parts 80,85, and 86,65 FR 6698 (Feb. 10,2000)

7 US. EPA, “Control of Emissions of Air Pollution from 2004 and Later Model Year Heavy-Duty Hghway Engines and Vehicles; Revision of %ht- Duty On-Board Diagnostics Requirements”, 40 CFR Parts 85 and 86,65 FR 59896 (Oct. 6,2000)

8 US. EPA, “Control of Air Pollution from New Motor Vehicles: Heavy-Duty Engine and Vehicle Standards and Hghway Diesel Sulfur Control Requirements”, 40 CFR Parts 69,80, and 86 (Dec. 21,2000) California Air Resources Board, Risk Reduction Plan to Reduce Particulate Mattm Emissions fiom Diesel-Fueled Engines and Vehicles, Sacramento, CA, Oct. 2000

9

The Author Bruce Bertelsen is the Executive Director of the Manufacturers of Emission Controls Association in Washington, OC, U S A .

Definitions and Terms Used Adjusted loaded vehicle weight - the numerical average of vehicle curb weight and GVWR

Gross vehicle weight rating (GVWR) - the value specified by the manufacturer as the maximum design loaded weight of a single vehicle

Heavy-duty vehicle (HDV) - any motor vehicle rated at more than 8500 Ibs GWVR or that has a vehicle curb weight of more than 6000 pounds or that has a basic vehicle frontal area in excess of 45 square feet

Heavy light-duty truck (HLDT) -any light-duty truck rated greater than 6000 Ibs GVWR

Light-duty truck (LDT) -any motor vehicle rated at 8500 Ibs GVWR or less which has a vehicle curb weight of 6,000 Ibs or less and which has a basic vehicle frontal area of 45 square feet or less, which is: (a) designed primarily for purposes of transportation of property or is a derivation of such a vehicle; or (b) designed primarily for transportation of persons and has a capacity of more than 12 persons; or (c) available with special features enabling off-street or off-highway operation and use

Light-duty truck 1 (LDTl) -any light light-duty truck up through 3750 Ibs loaded vehicle weight

Light-duty truck 2 (LDTP) - any light light-duty truck greater than 3750 Ibs loaded vehicle weight

Light-duty truck 3 (LDT3) - any heavy light-duty truck up through 5750 Ibs adjusted loaded vehicle weight

Light-duty truck 4 (LDT4) - any heavy light-duty truck greater than 5750 Ibs adjusted loaded vehicle weight

Light-duty vehicle (LDV) - a passenger car or passenger car derivative capable of seating 12 passengers or less

Light light-duty truck (LLDT) - light light-duty truck means any light-duty truck rated up through 6000 Ibs GVWR

Loaded vehicle weight (LVW) -the vehicle curb weight plus 300 Ibs

Medium-duty passenger vehicle (MDPV) -any heavy-duty vehicle with a GVWR of less than 10,000 Ibs that is designed primarily for the transportation of persons. The MDPV definition does not include any vehicle which: (a) has a seating capacity of more than 12 persons; or (b) is designed for more than 9 persons in seating rearward of the driver’s seat; or (c) equipped with an open cargo area of 72.0 inches in interior length or more

Vehicle curb weight (VCW) -the actual or the manufacturer’s estimated weight of the vehicle in operational status with all standard equipment, and weight of fuel at nominal tank capacity, and the weight of optional equipment computer in accordance with 40 CFR 86.082-24

Acronyms and Abbreviations

ARB California Air Resources Board HCHO formaldehyde CI compression ignition HDE heavy-duty engine CVT continuously variable transmission HDV heavy-duty vehicle EGR exhaust gas recirculation HLDT heavy light-duty truck gbhp-hr grams per brake horsepower-hour Ib pound GVWR gross vehicle weight rating LOT1 light-duty truck 1

Phfinum Metah Rw., 2001, 45, (2) 58

I Acronyms and Abbreviations, contd. LDTP LDT3 LDT4 LDV LEV LLDT MDE MDPV NLEV

light-duty truck 2 light-duty truck 3 light-duty truck 4 light-duty vehicle low emission vehicle light light-duty truck medium-duty engine medium-duty passenger vehicle National Low Emission Vehicle

NMHC NMOG NOx 02 OED

PPm SCR SI suv

non-methane hydrocarbon non-methane organic gas nitrogen oxides oxygen on-board diagnostic parts per million selective catalytic reduction spark ignition sport-utility vehicle

Rhodmm Bicentenary Competition In an exciting two-year period in the early nine-

teenth century, the discovery of four of the platinum group metals was announced in London. Among these was rhodium, which was described by William Hyde Wollaston to the Royal Society on 24th June 1804 (1). To mark the approaching 200th anniversary of

the discovery of rhodium, Johnson Matthey has decided to hold a Rhodium Bicentenary Competition for a new research project involving any aspect of rhodium science, preferably aimed at the development of a new application. The prize will be the sponsorship of a Ph.D. studentship and a loan of metal with which to conduct the investigation. The competition is open worldwide to scientists in universities and institutes of advanced research who train future scientists.

All proposals for reseaich will be treated with confidentiality and ideas will not be disclosed outside Johnson Matthey. The proposers will be advised of any duplication of ideas or projects. The successful project will have contact with Johnson Matthey sci-

entists over its duration. With due regard to the policies of the institution to which the scientists taking part belong, it is assumed that any intellectual propeq rights atising during the research will become owned by Johnson Matthey, should the project be developed into a commercial product.

Scientists wishing to participate in the Rhodium Bicentenary Competition should submit a 1-page research proposal directly by E-mail to: [email protected] by 1st October 2001. Proposals will be evaluated by a committee chaired

by the Director of the Johnson Matthey Technology Centre. More detailed proposals may be requested after the initial assessment. An announcement of the winner will be made in the January 2002 issue of Pkdinum Metals Review.

Reference (1) Donald McDonald and Leslie B. Hunt, “A History

of Platinum and its Allied Metals”, Johnson Matthey, London, 1982, p. 147

Biomimetic Chiral Rhodium Catalysis Recent attempts to mimic the high activity of

metalloenzymes involve the molecular imprinting of organometallic systems. This involves a polymerisation reaction in which a pseudosubstrate is attached to a catalyst centre. On removal a shape- selective cavity is left.

Researchers at the Institut fiii Anorganische Chemie der Ludwig-Maximilians-Universitat, Germany, now report a hghly active and selective (ee > 99’30) chiral RhQIII) catalyst which can asym- metrically reduce acetophenone (K. Polbom and K. Severin, Eur. J. Inotg. Chm., 2000, (8), 1687-1692). The organometalLic Cp*Rh complex had a chiral N, ”-chelate hgand with a styrene side chain, the remaining coordination site was occupied by a methylphenylphosphinato hgand - the pseudosubstrate which mimics acetophenone. During molecular imprinting, the Rh complex was co-poly- merised with ethylene glycol dimethacrylate; the phoshinato &and in the resulting polymer was then replaced by a chloro hgand to generate a shape- selective cavity near the active rhodium centre.

PhiinumMefalr Rev., 2001,45, (2) 59

Catalvtic Polvmerisation of Cvcloolefins J .J .J

CATALYTIC POLYMERIZATION OF CYCLOOLEFINS. IONIC, ZIEGLER-NAllA AND RING-OPENING METATHESIS POLYMERIZATION

BY V. DRAGUTAN AND R. STRECK, Elsevier, Amsterdam, 2000,1272 pages, ISBN 0-444-89519-1, €351.68, U.S.$406

This book represents a comprehensive survey of the polymerisation of cycloolefins by, as the subtitle indicates, all pertinent polymerisation methods. By any standards the discussion of such a broad field is a monumental task, and this is reflected in the size of the book which has 18 chapters and covers 1247 pages plus index. It is Volume 131 of “Studies in Surface Science and Catalysis” and one of the longest in this well- known series.

The purpose of the book is to survey the avd- able literature including patent publications on polymers derived from cyclic olefins, with emphasis on the monomers and their chemistry, rather than on catalysts and reaction mechanisms. One of the authors (R. Streck) is an industrial chemist, which helps to emphasise the applications angle. The abundance of material covered leads to a fairly dense text in the style of a review article. Literature up to 1999 is covered, although most references date from the 1960s through to the 1980s. The inclusion of older material is certainly very useful and helps to put more recent research into context.

Chapter 1 introduces some general principles of Ziegler-Natta and ring-opening metathesis polymerisation (ROMP) chemistry and introduces the main polymer types that can be produced. However, there is no information on reaction mechanisms and catalysts here - the discussion of this fundamental aspect is delayed until Chapter 15. Chapter 2 is a detailed discussion (98 pages) of the monomers and their synthesis.

Catalytic Systems Chapter 3 deals with catalytic polymerisation

systems and is subdivided into: (1) cationic, (2) anionic, (3) Ziegler-Natta, and (4) ROMP catalysts. The term ‘catalyst’ is used rather widely, and no distinction is made here between a true catalyst, that is a metal centre involved in every reaction

step, and initiators like those present in cationic and anionic polymerisations. The emphasis is clearly on ROMP catalysts, which are quite extensively covered, and includes ‘classical’ platinum metal catalysts such as ruthenium, osmium and iridium chlorides, as well as Grubbs-type ruthenium catalysts. By comparison, the description of the commercially much more important Ziegler-Natta systems is rather limited. Section (5) of Chapter 3 deals with some catalyst synthesis.

Chapter 4 discusses reaction conditions, such as the effect of monomer concentration on ROMP catalysts, of catalyst concentration (mainly of metathesis catalysts), of the reactant ratio, and of the reaction temperature. Chapter 5 describes the cationic polymerisation of cycloolehns, followed in Chapter 6 by a brief discussion of anionic, lithium alkyl-initiated polymerisations.

The discussion of Ziegler-Natta polymerisations (Chapter 7) is ordered according to ring size, from 4- to 9-membered cycloolefins. This section deals mostly with classical Ziegler-Natta catalysts based on early transition metal halides activated with aluminium alkyls, although on occasions molybdenum or rhenium metathesis systems make an appearance. There is extensive coverage of the polymerisation of norbomene, norbomadiene and functionalised cyclic olefins with a variety of soluble palladium catalysts, including aqueous emulsion polymerisations catalysed by palladium chloride or acetate.

ROMP Reactions Chapter 8 deals with ROMP of cycloolefins and

with 356 citations is the most extensively referenced chapter in the book, compared to 50 references on Ziegler-Natta catalysis. Again the monomers are treated in order of ring size. Most catalyst systems discussed are based on vanadium, molybdenum, tungsten and rhenium, with some mention of ruthenium and other noble metal catalysts. This is

Phfimm Met& Rm, 2001, 45, (2), 6 W 1 60

followed in Chapter 9 by a discussion of ROMP of hctionalised monomers, catalysed by ruthenium as well as molybdenum and tungsten complexes, and in Chapter 10 with the description of ROMP of heterocyclic olefins by tungsten and, mainly, ruthenium catalysts.

Copolymerisations of Cycloolefins Chapter 11 deals with the large area of copoly-

merisations involving cycloolefms. Not surprisingly in view of the extensive literature, it is the longest in the book (187 pages). Structure and properties of poly(cycloo1efins) are discussed in Chapter 12, thermodynamic aspects in Chapter 13, and reaction kinetics in Chapter 14. Aspects of polymerisation mechanisms are the topic of Chapter 15. It is subdivided into sections on cationic, anionic, Ziegler-Natta and ROMP. while the Ziegler-Natta discussion is rather rudimentary and deals mainly with the 1,2- to 1,3-isomerisation during the polymerisation of cyclopentene, the ROMP section is quite comprehensive. Chapter 16 is concerned with the stereochemistry of cycloolefin polymerisations.

While up to this point the authors have followed strictly the title of the book and focused exclusively on cyclic olefins, Chapter 17, entitled ‘Related Processes’ is, somewhat surprisingly, concerned with the cationic, anionic and Ziegler-Natta polymerisation of non-cyclic monomers: isobutene, styrene, butadiene and I-alkenes. Even d h n e metathesis, olefin isomerisation, atom transfer radical polymerisation of vinyl monomers (including ruthenium catalysed reactions) and the metathesis of olefins and acetylenes are covered. The section on ring-closing metathesis with Grubbs-type ruthenium catalysts is a useful demonstration of the versatility of this method in synthetic applications.

Applications and Outlook Finally, Chapter 18 deals with practical applica-

tions and commercial products. Some of these are discussed in relative detail, although overall one might wish for more precise information on actu- ally commercialised products and their market sizes. In view of recent mergers and acquisitions

the list of manufacturers grouped by country is now of limited use. Few production figures seem up-to-date.

The book is fairly free of errors, although some of them are rather glanng. This starts with Chapter 1: Equation (1.2) refers to vinyl polymerisation, the label ‘ROMP’ is misplaced. Equation (1.15) shows &/trans ROMP isomers and not the iso/syndiotacticity claimed in the text. In Chapter 3, structures 6-9 of unsa-zirconocenes (and their copies in subsequent chapters) show the undesirable meso- rather than the correct rac-isomers.

The text is densely written, and space is limited. This being so, one wonders, for example, whether it is really necessary in the section on catalyst synthesis to include equations for the preparation of compounds such as AlC13, HF and ZnClz. In the section on ansa-zirconocene syntheses, the repetition of very similar reaction schemes for closely related ltgands hardly seems justified. The index, by contrast, is rather sparse. For example, the entry ‘ruthenium catalysts’ refers only to Chapter 3 but gives no hint to the extensive coverage of these compounds in Chapters 8 and 9. One will search in vain for keywords such as ‘iridium’, ‘osmium’ and even ‘palladium’.

This book is addressed to the specialist with detailed knowledge of the underlying catalytic chemistry. It provides a wealth of references to the primary literature, and the authors are to be con- gratulated on undedmg such a large task so comprehensively. There is, however, little discussion and evaluation, which is regrettable since more overviews, summaries and informed re-evaluations of earlier results would have been helpful to the less experienced reader. Anyone already concerned with cycloolefh polymerisation and especially ROMP chemistry, as well as those wishing to familarise themselves with this area, for example, at the start of a new research project, will find this book a most valuable source.

MANFRED BOCHMANN

Manfred Bochmann is Professor of Inorganic Chemistry at the University of East Anglia, returning last year from the University of Leeds where he was Head of Inorganic and Structural Chemistry. He is co-director, with Professor M. J. Cook, of the newly created Wolfson Materials and Catalysis Centre at the School of Chemical Sciences. His research focuses on catalysis of Ziegler-Natta and cationic olefin polymerisations.

Phbmm Met& Rey., 2001, 45, (2) 61

Ruthenium in Medicine: Current Clinical Uses and Future Prospects By Claire S. Allardyce and Paul J. Dyson Department of Chemistry, The University of York, Heslington, York YO10 5DD, U.K

There is no doubt about the success of precious metals in the clinic, with,,for example, platinum conipounds being widely used in the treatment of cancel; silver compounds being useful antimicrobial agents and gold compounds used routinely in the treatment of rheumatoid arthritis. The medicinal properties of the other platinum group metals are now being recognised and of these ci ruthenium anticancer agent has recently entered the clinic, showing promising activity on otherwise resistant tumours. Like all nietul drugs, the activity of the ruthenium cornpounds depends on both the oxidation state and the ligands. By manipulating these features rutheniurn-centred antimalarial, antibiotic and immunosuppressive drugs have been made. I n addition, ruthenium has unique properties which make it particularly useful in drug design. In this review we discuss ruthenium from a clinical stunce and outline the medicinal uses qf

ruthenium- based compounds.

Precious metals have been used for medicinal purposes for at least 3500 years, when records show that gold was included in a variety of medi- cines in Arabia and China. At that time precious metals were believed to benefit health - because of their rarity - but research has now linked the medicinal properties of inorganic drugs to specific biological properties. The elucidation of a drug mechanism is however complex and the exact route of activity for many drugs remains unknown. The biological targets or mechanism of action of many metal drugs are now being resolved step by step, and this information is then used to design improved drugs with increased potency and reduced side effects.

Metals in the Clinic Perhaps the most well known and best studied

platinum metals drugs are the anticancer compounds of platinum itself which, after the fortuitous discovery of anticancer properties of cisplatin in the 1960s, heralded research into other platinum compounds and founded a revolution in cancer therapy. Today, many platinum drugs are used in the clinic and even more are being evaluated in clinical mals, not just to treat cancer but to fight a range of diseases, including parasitic and

bacterial infections. Other metals of the platinum group and gold and silver have been used in medicine and these are listed in the Table.

Ruthenium Properties Suited to Biological Applications

There are three main properties that make ruthenium compounds well suited to medicinal application: (i) rate of ligand exchange (ii) the range of accessible oxidation states and (iii) the ability of ruthenium to mimic iron in binding to certain biological molecules. These will be briefly described in turn.

(i) Ligand Exchange Many ruthenium complexes have been evaluat-

ed for clinical applications, particularly in the treatment of cancer, due in part, to Ru(II) and Ru(I1I) complexes having similar ligand exchange kinetics to those of PtQl) complexes. L p n d exchange is an important determinant of biological activity, as very few metal drugs reach the biological target without being modified. Most undergo interactions with macromolecules, such as proteins, or small S-donor compounds and/or water. Some interactions are essential for inducing the

Pkatium Met& h., 2001,45, (2), 6 2 4 9 62

Fig. I The uxidation state changes of ruthenium in cancer and healthy cells. The reductive environment of cancer cells favours Ru(II). which is more biologically active than Ru(III). Hence Ru( III) compounds are essentially prodrugs that become activated by reduction on reaching the cancer cell

activity

targeted delivery

R u ( l l l ) d b Ru(lll) fromdrug administration

Oxidation: molecular oxygen enzymes

desired therapeutic properties of the complexes. As the rate of hgand exchange is dependent on the concentration of the exchangmg hgands in the sui-

rounding solution, diseases that alter these concentrations in cells or in the surroundmg tissues can have an effect on the activity of the drug.

(ii) Oxidation State Ruthenium is unique amongst the platinum

group in that the oxidation states Ru(Il), Ru(I1I) and R u m are all accessible under physiological conditions. In these oxidation states the ruthenium centre is predominantly hexacoordinate with essentially octahedral geometry, and R u g complexes tend to be more biologically inert than related R u m and (IV) complexes. The redox potential of a complex can be modified by varying the hgands. In biological systems glutathione, ascorbate and single electron transfer proteins are able to reduce Ru(IIl) and R u m , while molecular oxygen and cytochrome oxidase readily oxidise R u m .

The redox potential of ruthenium compounds can be exploited to improve the effectiveness of drugs in the clinic. For example, the drug can be administered as relatively inert Ru(I1I) complexes, which are activated by reduction in diseased tissues. In many cases the altered metabolism associated with cancer and microbial infection results in a lower oxygen concentration in these tissues, compared to healthy ones, and this pro- motes a reductive environment. Cancer cells are known to have higher levels of glutathione and a

lower pH than healthy tissues, creating a strongly reducing environment. If the active Rug9 complex leaves the low oxygen environment, it may be converted back to Ru(I1I) by a variety of biological oxidants, see Figure 1.

Proteins that can catalyse the reduction of Ru(I1I) to Ru(II) include mitochondrial and microsomal single electron transfer proteins. The mitochondrial proteins are of particular interest in drug design as apoptosis, the desired mechanism for cell death, can be initiated in the mitochondria, as well as by other pathways, for instance, by the Fas/FasL pathway. Transmembrane electron- transport systems can also reduce Ru(I1I) complexes outside of the cell and this is hghly relevant to the mechanism of action of a ruthenium- based drug in clinical use which has anticancer activity independent of cell entry (vide inpa).

(iii) Iron Mimicking The low toxicity of ruthenium drugs is also

believed to be due to the ability of ruthenium to mimic iron in binding to many biomolecules, including serum transferrin and albumin. These two proteins are used by mammals to solubilise and transport iron, thereby reducing its toxicity. Since rapidly dividmg cells, for example microbial- ly infected cells or cancer cells, have a greater requirement for iron, they increase the number of transferrin receptors located on their cell surfaces, thereby sequestering more of the circulating meta- loaded transferrin. In #uo, the exact increase in

Phtimm Metals Rev., 2001, 45, (2) 63

a@: Cancer cell 0 0 Ruthenium loaded transferrin - Transferrin receptor

Fig. 2 Schematic representation of the selective uptake of transferrin by cancer cells. Ruthenium can mimic iron in binding to transferrin. Metal-loaded rransferrin is delivered to cells according to the number of transferrin receptors on their surfaces. As most cancer cells have a higher number of transferrin receptors (left), compared to healthy cells (right), ruthenium is targeted to cancer cells

radio-labelled ruthenium compounds in cancer cells, compared to healthy cells, has been shown to range from 2-12 fold, depending on the cell type. As the drug is targeted to cancer cells, its toxicity is reduced because less of it will reach healthy cells, see Figure 2.

Current Uses of Ruthenium-Based Drugs

The array of clinical applications for some platinum group metals, see the Table, illustrates the versatility of metallodrugs in the clinic. The activity of each compound is a function of the oxidation state of the metal and the nature of the attached lgands. These features dictate not only how the drug interacts with the disease target but also the biological transformations that occur en route. By manipulating these features activity can be fme- tuned to maximise the potency but minimise the general toxicity of the drugs.

Immunosuppressants Immunosuppressants, for example, cyclosporin

A, are important clinical agents used in the treatment of a broad range of diseases, including aplastic anaemia, severe eczema, glomerulonephr- us, psoriasis, systematic sclerosis and psoriatic arthritis. Cyclosporin A has a number of side effects including renal disease, hypertension and

nausea, hence there is a continual drive to develop a more effective drug.

RuQII) complexes with N-donor ligands were tested as immunosuppressants, with cis- ~u(NH3),(Im),], Im is imidazole, see Figure 3, being particularly effective. These compounds are very stable and have been shown to inhibit the antigen-independent phase of T-cell proliferation at nanomolar concentrations - a marked improvement on cyclosporin - and hence have much potential for clinical development.

Antimicrobial Ruthenium complexes are active against a wide

range of parasitic diseases including malaria and Chagas’ disease. The activity of organic antimicrobial drugs has been enhanced by bin+ the organic molecule to a ruthenium centre. The enhancement is due, in part, to the ruthenium complex overcoming resistance that the parasite has developed to the organic compound alone. Malaria threatens over 40 per cent of the world’s population and the malaria-causing Phmodium parasite is becoming resistant to some of the most successful drugs, such as chloroquine. The resistance mechanism of Phmodium parasites to chloroquine involves a reduced rate of uptake of the drug. However, it has been found that metal complexes of chloroquine partially restore the antimalarial activity. The RuQl)-chloroquine complex, ~~Cl~(chloroquine)]~, is 2-5 fold more effective than chloroquine alone, suggesting that the ruthenium complex is taken up by a different mechanism to the chloroquine. The smcture of ~uCl,(chloroq~ine)]~, see Figure 3, has not been fully established and some uncertainty remains as to its precise structure. It is thought that, once in the Phmodirrm parasite, the ruthenium complex behaves in a similar way to chloroquine, altering the pH of the digestive vacuole of the parasite and inhibiting the polymerisation of heme (the heme is toxic to the parasite which therefore dies).

The T@anosoma me parasite causes Chagas’ disease. Chagas’ disease affects millions of people in Latin America and is incurable. The current treatment involves noxious organic drugs, the dose being limited by the toxicity of the therapy. Once

Pkatinnm Metah REV., 2001,45, (2) 64

Some Medicinal Properties of the Precious Metals

(Not all of these compounds have been clinically approved)

Ru Immunosuppressant Cancer Dental alloys Microbial (malaria and

Chagas’ disease) Antibiotic Septic shock

I

0s Dental alloys Microbial (Leishmaniasis) Rheumatoid arthritis

Rh Cancer Radiosensitisers Dental alloys Microbial (malaria and

Leischmaniasis) Bacterial infections

Ir Radioisotopes in cancer

again, the effectiveness of these organic drugs can be dramatically enhanced by coordination to ruthenium centres.

Antibiotics Coordinating ruthenium to organic antibiotic

compounds often results in %her in vjtm activity. A good example is the ruthenium(III) derivative of thiosemicarbazone; this exhibits a 70 per cent increase in antibiotic activity against the Gram negative bacteria Salmonelka @bi and Entembacteria fmcaks. It is postulated that the improved activity arises from the delocalisation of the positive charge between the organic moiety and the metal ion, which favours the drug entering the normal cellular processes of the bacteria. However, it is also possible that the difference in activity stems from the ability of R u m to bind to biological molecules, in a similar way as iron. It is believed that siderophore compounds are secreted by microorganisms to sequester iron from their sur- rounding environment. Therefore, if the rutheniumo complexes also bind to siderophores they wiU be more readily taken up by the cell.

Nitric Oxide Scavengers Nimc oxide (NO) plays a central role in many

physiological processes indudmg agnalhg, regulation of cardiovascular function and immunological

Pd Viral (leukaemia and

HIV) Cancer Dental alloys

PI Cancer Dental alloys Microbial Anti-HIV

Ag Dental alloys Smoking Microbial

Au Cancer Viral (HIWAIDS) Bronchial asthma Microbial (malaria) Rheumatoid arthritis

response to microorganisms and tumour cells. Consequently, malfunction of NO production results in many physiological symptoms.

Some ruthenium@) polyaminocarboxylates, such as -6245 and AMD1226, see Figure 3, have been shown to enhance the activity of vaso- constrictor drugs and are proposed for the treatment of diseases that involve overproduction of NO includmg stroke, septic shock, arthritis, inflammatory bowel disease, epilepsy and diabetes. The edta complexes Kpu(Hedta)OH;] and Kpu(Hedta)C1] exist in equilibrium in aqueous solution. Both species bind NO rapidly and strongly, resulting in the reduction of the Ru(IIl) ion to form a linear Rum-NO adduct.

Anticancer Activity Despite the success of platinun-based anti-

cancer compounds in the dinic, there is still a need for new and improved metal-based anticancer drugs. The need for new drugs is fuelled by the inability of platinum compounds to tackle some types of cancer of hlgh social incidence and by the associated toxic side effects of the current platinum compounds in clinical use.

Platinum anticancer drugs bind DNA, causing damage that prevents protein synthesis and repli- cation causing cell death. The success of platinum anticancer drugs has biased the screening of new

Pkztinm Mehh Rev., 2001,45, (2) 65

Immunosuppressant H

HjN' I .N>

N H 3 LNH cis- [ R U ( N H ~ ) ~ ( I ~ ) ~ ]

Anticancer

CI

cis- [RuCIz( DMS0I2 (4 -NO 21 mI2]

"N)-" I

fI A M D 6 2 4 5

Ruthenium red

AMD1226

cis- [RuClq(lndarole)2]

NAMI RAPTA

Fig. 3 The structures of various medicinal rutheriiuni cornplexes. The structure of the chloroquine complex [RuCI2(chloroquine)lz remains uncertciin. NAMI is the Nri' snlt and NAMI-A is the iniidrrzoliian .ctrlt. RAPTA compounds, with CSHO, GH.Me, C~H&le'Pr-1.4 and &Wees. htive been ninde

metal-based anticancer compounds towards look- ing for damage caused to DNA. Many Ru(Il), Ru(I1I) and R u m complexes with amine, dimethylsulfoxide, imine, polyaminopolycarboxy late, and N-heterocyclic ligands have been found to bind to DNA, see Figure 3. However, many of these compounds are barely soluble in aqueous solution, which is necessary to allow efficient administration and transport. Solubility has been increased by using dialkyl sulfoxide derivatives, such as [&uns-RuC~(DMSO)Im] m, N M - A , see Figure 3, which is now recognised as the most successful ruthenium-based anticancer compound.

Interestingly, although NAMI-A can bind DNA, in vivo DNA damage does not appear to be

part of its anticancer mechanism. In general, anticancer activity hinges on the

ability of a drug to bring about apoptosis (pro- grammed cell death) of the tumour cells. Apoptosis is a complicated process by which the cell 'commits suicide' in a controlled manner such that there is no cell debris or damage done to SUE

rounding cells. This process is perhaps best illustrated on a cellular level using neuroblastoma cell lines: growing cells are semi-differentiated, forming irregular shapes that can be clearly distinguished from the spherical apoptotic bodies, see Figure 4. Alternatively cells can die by a process called necrosis, which is less controlled, and causes inflammation and damage to adjacent cells.

Platinum Metah Rev., 2001,45, (2) 66

There are many mechanisms by which apoptosis can be initiated involving interactions of drugs with both DNA and proteins. Some ruthenium complexes have been shown to damage DNA, either directly or indirectly, for example, by posi- tioning radiosensitisers close to the DNA. In addition to DNA bindug ruthenium compounds interact with proteins, and it is likely that both activities contribute to the anticancer properties of the compounds.

(a) DNA Damaging Agents A number of ruthenium compounds have been

shown to bind DNA in vjh and there is a direct correlation between this activity and the cytotoxi- city of Ru(III) am(m)ine complexes in tissue culture. The mechanism of DNA bin- has been probed and certain ruthenium complexes form cross-links between DNA strands - possibly favoured due to the steric restrictions imposed by the octahedral geometry of the complexes. This bin- mechanism differs from the intrastrand cross-links favoured by cisplatin, and consequently the cancer cell lines that have developed resistance to cisplatin by accelerating the rate of repair of intrastrand cross-links are st i l l susceptible to ruthenium anticancer drugs.

Interestingly, it has been demonstrated that R u O complexes are far more reactive towards DNA than RuQIIT) AND R u m and it is therefore possible that the anticancer activity of Ru(III) involves initial reduction to R u m at the tumour site, promoted by the altered physicochemical environment in tumour cells (I& s~pm) . If this hypothesis is correct then R u m complexes are essentially prodrugs. However, there is growing evidence to show that protein interactions are also

extremely important in the anticancer activity of ruthenium compounds and these interactions could occur with the ruthenium in either oxidation state.

(b) Radiosensitisers Radiation therapy is routinely used against

some types of cancer. This treatment can be enhanced by using nitroimidazoles and halogenat- ed pyrimidine radiosensitisers (compounds that increase the irradiation sensitivity of the target

cells). As the activity of these compounds depends on their proximity to DNA, coordinating radiosensitisers to metals that are able to bind to DNA, for example platinum and ruthenium, enhances the radiosensitising properties.

The two key features of an effective radiosensi- tiset are the ability to bind DNA and the redox potential of the bound complex. Strong DNA bin- affinity is a feature of many ruthenium compounds, although not all have dosemitising activity. This activiq depends upon the compound having a high reduction potential, which can be optimised by the use of appropriate ligands. For example, the nitroimidazole complex, RuClz(DMSO)z(4-N021m)2, see Figure 3, is one of the most effective radiosensitisers having both a hgher activity and a lower toxicity than 4-NOz- imidazole alone.

(c) Photodynamic Therapy As with radiotherapy, photodynamic therapy

uses chemicals targeted to diseased cells. The chemicals become cytotoxic when exposed to electromagnetic radiation. For example, nitrosyl- ruthenium@) complexes release NO on reduction; the reduction may be triggered using photodynamic methods. Until recently, the application of photodynamic therapy was restricted by the poor accessibility to cancer cells, but a unique approach using ruthenium complexes has been developed which overcomes these restrictions. This new method of therapy centres on the Mossbauer absorption of y-rays by ruthenium; this can induce emission of Auger electrons which damage the DNA to which the Ru is bound.

(d) Antimitochondrial Apoptosis can be initiated by more than one

pathway, one being via the mitochondria (the sub- cellular compartments associated with energy and heat generation). Consequently any compounds that target these structures are of great interest as anticancer drugs. Ruthenium red, see Figure 3, is routinely used by biologists to sta in mitochondria selectively, as it binds to the calcium channels on their surfaces and has long been known to inhibit tumour cell growth, but its toxicity is too great for

Phrinwm Me~kLr Rey., 2001,45, (2) 67

Fig. 4 Photographs of human neuroblastoma cells in culture grow to a high density and have an irregular shape (left). After incubation with 1.3 pM of the ruthenium drug RAPTA-C there are fewer cells in the culture (right). The smooth, more spherical appearance of the remaining cells is characteristic of apoptotic bodies, indicating cell death is occurring by apoptosis. Each cell has the average dimensions of 20-40 pm

use in the clinic. It is possible that the anticancer mechanism of some other ruthenium compounds may involve mitochondtial interactions. However, many ruthenium compounds with putative antitu- mour activity are unlikely to act like ruthenium red.

(e) Antimetastases A particularly challenging area of cancer thera-

py is the treatment of metastases. Metastasis occurs at a late stage of the disease and involves the escape of cells fiom the primary tumour and their reestablishment at distinct secondary loca- tions. The metastases are normally dormant and are often suppressed by hormones secreted from the primary tumour. However, if the primary tumour is removed or there are M e r genetic changes in the metastases, growth can begin. Tumour growth beyond about 1 mm3 requires a blood supply, and the formation of the necessary blood vessels is termed angiogenesis. Some antimetastases drugs restrict angiogenesis, for example angiostatin, throbospondin and badmas- tat, but statistics show that once this process has occurred the chance of five-year survival drops by about 50 per cent, dependmg upon the type of cancer.

The first ruthenium anticancer drug to progress

through clinical trials, [hzm-RuCL+(DMSO)Im]- m, NAMI-A, see Figure 3, is strongly active against tumour metastases. NAMI-A appears to alter protein expression, either by binding to proteins or to RNA, causing thickening of the protein layer surroundmg turnouts and metastases. As a result the tumour becomes isolated, preventing escape of metastasing cells and reducing the blood flow, which ultimately suffocates it. Only a very small portion of the drug reaches the tumour target and its activity appears to be independent of its concentration in tumour cells. Rather, it appears that NAMI-A has an extracellular mode of activity centring on interactions with proteins.

In our own laboratory we have investigated the role of the llgands attached to ruthenium in the passive diffusion of the drug across cell mem- branes, facilitating the movement of the drug into and within cells. A series of drugs of formula [Ru(arene)Cl~PTA], RAPTA, see Figure 3, have been developed that interact with proteins and DNA in v j h , triggering apoptosis in human cancer cell lines. Thepcymene derivative, RAPTA-C, has activity against, for example, SK-N-SH neuroblastoma cells, inducing apoptosis in nanomolar concentrations, see Figure 4. This cell line was derived from the metastases of a human neuro-

Pbftinm Me& Rav., 2001,45, (2) 68

blastoma that had metastasised to the bone mar- row. Figure 4 shows structurally distinct forms. In tissue culture, cells grow in the S-form, which is partially differentiated and characterised by the irregular shapes of the cells. These cells undergo two responses to stress: full differentiation or cell death. Full differentiation is observed by the more ‘dendritic’ appearance of the cells, which occurs 1-3 hours after the stress. Subsequently cells either dedifferentiate back to the S phase - if the stress can be overcome - or die.

Concluding Remarks Ruthenium drugs are particularly important in

the clinic due to their low toxicity. This is in part due to the ability of ruthenium to mimic the binding of iron to biomolecules, exploiting the mechanisms that the body has evolved for non- toxic transport of iron. In addition, the redox potential between the different accessible oxidation states occupied by ruthenium enables the body to catalyse oxidation and reduction reactions, depending on the physiological environment. As demonstrated for cancer tissues, but also true in other diseased states, the biochemical changes that accompany disease alter the physiological environment, enabling ruthenium compounds to be selectively activated in diseased tissues. These two features combine to give ruthenium drugs a remarkably low toxicity compared to other platinum group metal compounds and therefore make ruthenium compounds promising in the clinic.

Acknowledgement Paul J Dyson would like to thank the Royal Society for a

University Research Fellowship.

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S. P. Fricker, ‘Nitrogen monoxide-related disease and nitrogen monoxide scavengers as potential drugs‘, in “Metal Ions in Biological Systems”, Volume 36, eds. A. Siegel and H. Siegel, Marcel Dekker Inc., New York, 1999, pp. 665-721 (A review on metal compounds and nitric oxide focusing on ruthenium compounds)

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S. P. Fricker, ‘Ruthenium, Nitric Oxide and Disease’, Phtinum Me& RUE, 1995,39, (4), 150-159

The Authors Paul Dyson is a Royal Society Fellow in inorganic chemistry at the University of York. His interests are in functional ligand design for catalysis and medicine.

Claire Allardyce is a Research Fellow at the University of York. Her main interests are in biological structure in relation to toxicology and drug design.

Thiazepinones Synthesis with Rhodium Thiazepinones are pharmaceuticals with poten-

tial use in the treatment of heart and inflammatory diseases. The 7-membered heterocycles have been prepared in multistep syntheses in which chirality is introduced before or during a transformation.

Researchers at the University of Ottawa, Canada, now report the synthesis of thiazepinones using cyclohydrocarbonylative ting expansion of acetylenic thiazoles in the presence of CO and Hz, via the zwitterionic rhodium complex catalyst (?f- C&lJ3Ph&Rh’(l,5-COD) with added triphenyl phosphite (B. G. Van den Hoven and H. Alper,]. Am. Chsm. SOC., 2001,123, (6), 1017-1022).

The transformation of the simple and functionalised 5-membered acetylenic thiazoles with CO and Hz to 7-membered 2-(Z)-6-(@-4H-[1,4]-thi- azepin-5-ones occurred in 61 to 90 per cent yields with good chemo- and regioselectivities, at 70-1 10°C, after 18 to 36 hours. A model substrate of 2-hex-1-ynylthiazole was used to optimise the cyclohydrocarbonylation and ring expansion of 2- acetylenic thiazoles. The acetylenic unit can have various subsdruents in positions 4 and 5 of the thi- azole ring as well as akyl-, ether-, ester-, vinyl-, and ary-substituted alkynes at position 2. The process is general and may be pharmaceutically interesting.

PLdin~m Met.& Rev., 2001,45, (2) 69

New European Autocatalyst Plant at Royston LATEST FACILITY INTRODUCES NOVEL CATALYST PRODUCTION TECHNOLOGY

In March 2001 the latest Johnson Matthey autocatalyst manufacturing plant was opened at Royston in the U.K. The facility uses advanced production technology to manufacture the latest generations of emission conttol catalysts for European customers. The catalysts, for gasoline- and diesel-fuelled vehicles, comprise salts of platinum, palladium and rhodium on metal and ceramic substrates. This plant gives Johnson Matthey the ability to manufac-

The new European

uutocatalyst plant at Royston

in the U.K. The plant

uses novel robotics to control the production of car and

diesel catalysts

ture the most advanced autocatalysts to match the increasmgly tighter specifications required for present and future generations of clean cars. The plant is located dose to the European Autocatalyst Technology Centre, so new technology can be rapidly transferred from development to full-scale production.

The plant, with an initial capacity of 3.5 million autocatalysts per year, has been designed for flexible manufacturing. It can cope with the increasing complexity of catalyst technology and is designed in discrete, but fully integrated, production lines to allow extta capacity to be added quickly. Robots are exclusively used to handle parts during the manufacturing process. This speeds up operations and the robotics allow for quite sophisticated manipulation of the substrates as they pass through the catalyst manufacturing process.

A fully integrated computer-controlled system controls the manufacturing process and runs the

specially-developed materials handhug system. The latter controls the preparation of all materials used in production. This enables the tightest spedfica- tions to be met to ensure optimum performance from the finished catalyst. The facility has been designed to use every gram of raw material input into the process, produces no waste and is thus very

environmentally friendly. The new plant was completed in

under 11 months and the expertise acquited is being utilised as the technology is disseminated around the world. A major expansion of the production line is already planned. The new technology has been installed in Johnson Matthey facilities in Belgum, the U.SA. and South Africa and there are plans for further expansions and major

The oven recovers waste heat for eficient energy use. Advanced materials handling techniques and pollution suppression devices maximise yields and eliminate wastage

investments at the other Johnson Matthey manu- factufing sites. These new production methods embody a major change in autocatalyst manufacturing techniques aimed at keeping Johnson Matthey at the forefront of this important environmental technology. GAVIN YOUNG

Gavin Young is Projects Director for Johnson Matthey CSD, responsible for the construction of the European Autocatalyst plant and for expenditure in the European region. His background is in precious metals, including refining and autocatalyst manufacture.

PMnnUm Mekdr Rav., 2001,45, (Z), 70 70

Exhaust Emissions Control Developments A SELECTIVE REVIEW OF THE DETROIT 2001 SAE WORLD CONGRESS

The Society of Automotive Engineers’ (Sm) Detroit World Congress in the Cob0 Center (5th-8th March) was a great success, with some 50,000 delegates, and about 1300 technical presentations. There were many well-attended sessions on the control of engine exhaust emissions, and this selective review focuses on papers concerned with platinum group metal @gm) catalysts. Platinum oxidation catalysts are used in selective catalytic reduction systems which use ammonia or urea, but these are not discussed here. The reference numbers of papers mentioned are given, most being available in S A E ‘‘Smgle Publications” (1).

Three-Way Catalysts With Conventional gasoline engines, the first

objective in obtaining the very strict legislated hydrocarbon (HC) emissions requiring 99% conversion is to have the catalyst operating (hght-off) within seconds of star t ing the engine. To achieve this a low-temperature light-off catalyst and an engine staa-up procedure that rapidly heats the catalyst are required. It is essential to minimise heat losses, and computer models are used to under- stand the interplay between various components.

Vokwagen (2001-01-0940) described a simulation package for calculating gas/solid heat and mass transfer in exhaust systems. They studied the effects of conventional single-wall exhaust pipes, pipes with air-gap insulation, flanges, and flexible couphgs. Their results indicated that conserving heat is essential for reducing catalyst hght-off times and HC emissions during the crucial first seconds. Excess oxygen was beneficial with standard catalyst heating strategies (lean operation of the catalyst), and having oxygen stored in the catalyst was important.

Volvo (2001-01-1311) reported a new lean start-up strategy for five- and six-cylinder engines. They described how the 99% conversion/lambda window graddy decreased with time. Partial zero emission vehicles (PZEVs) require 150,000 miles durability. Heat losses and catalyst warm-up time

are minimised by plaung the catalyst close to the exhaust manifold. But in this ‘close-coupled’ PO& tion, it can be subjected to exhaust gas pulsation, poor mixing and high-temperature excursions which could be detrimental to performance.

Nissan (2001-01-0943) modelled the gas flow and heat transfer for a close-coupled catalyst configuration, and concluded that during low engine-load conditions, for example during catalyst warming, it is difficult to concentrate the gas flow in the cenae of the catalyst and this can delay hght- off. The difficulty in obtaining SULEV emissions was illustrated by projects that failed to achieve them (2001-01 -1 31 3,2001 -01-1 314).

Threshold catalysts (deactivated so emissions are outside the legislative limits by a prescribed amount) are needed to calibrate on-board dlagnos- tic (OBD) systems. The catalysts are often made by very hgh-temperature treatments that can degrade the substrate. Shell, DaimlerChrysler and Emitec (2001-01-0933) reported that a hgh-temperature vacuum treatment can achieve required activation without causing substrate deterioration.

The price of palladium (2) has been an incentive to develop high performance TWCs based on Pt/Rh rather than Pd/Rh. A paper by DaimlerChrysler and dmc’ (2001-01-0927) described a durable two-layer Pt/Rh catalyst that at reduced pgm loadup could replace close-coupled and underfloor Pd/Rh catalysts on engines that rapidly warm the catalyst On engines with less rapid heating strategies Pd-based catalysts were favoured in close-coupled positions due to a better HC performance. Probably for similar reasons, ASEC (2001-01-0923) in some two-catalyst config urations, favoured a Pd-only ftont catalyst followed by a Pt/Rh catalyst I.@-off of the front catalyst was improved if it did not contain ceria, and had only a s m a l l oxygen storage capacity (OSC).

Ford and the Kunming Institute of Precious Metals (2001-01-0225) conhrmed thit relatively low-loaded pgm TWCs containing appropriate oxygen storage components can be used for

PIpbnwnr Metah Rcv., 2001,45, (2), 71-73 71

emission control in emerging markets. If carburet- ted Chinese cars were retrofitted with catalysts, emissions could be significantly reduced.

NOx-Trapping Catalysts Catalysts that store NOx as nitrate (NO33

under lean conditions, via nitric oxide (NO) oxidation over Pt to nitrogen dioxide (NOS, and which are reacted with a pulse of reductant (CO and HCs) to give Nz, are called NOx-traps or NOx- absorbing catalysts. These are being developed for use on lean-running gasoline and diesel engines. Temperatures below 550°C are required for efficient NOx removal, so NOx-traps are usually located underfloor.

Mitsubishi and ICT (2001-01-1300) discussed catalyst systems for direct injection gasoline engines, comprising a close-coupled TWC, an underfloor NOx-trap followed by a second TWC. The close-coupled TWC controls start-up HC (a Pd/Rh formulation was ongmally used). The OSC was minimal because stored oxygen increases the amount of fuel consumed during NOx-trap regeneration. Several Pt/Rh catalysts were evaluated in the close-coupled position. A single layer Pt/Rh catalyst had poorer HC oxidation performance under lean conditions than a Pd/Rh catalyst. Performance was substantially improved when the Pt and Rh components were in separate layers.

Toyota (2001-01-1297) modelled the duration of the rich pulse during NOx-trap regeneration. They confirmed that regeneration rate increases as

the duration of the rich pulse increases, and that heat produced during regeneration (and by reduction of stored oxygen) heats the downstream part of the NOx-trap causing NOx to be released. These effects are taken into account when designing and sizing NOx-traps. NOx-traps react with s u l f u r dioxide (SOZ) in exhaust gas, storing it as sulfate (SO4>). This gradually decreases the NOx capacity of the trap. To overcome this a NOx-trap must be periodically desulfated under rich conditions at temperatures higher than needed to remove stored NOx. Mild desulfation gives SO2, but rapid desulfation requires hgh temperatures and more strongly reducing conditions and may lead to undesirable HZS formation.

Ford (2001-01-1299) addressed this problem and described two methodologies to minimise HzS production; one used a ‘H1S getter’, such as a nickel compound that forms a stable sulfide; the second involved the use of short lean pulses during hgh-temperature rich desulfation. This was sufficient to re-oxidise sulfide to S02. The combination of both methods should be interesting. Alkali metals form stable nitrates, so could be

used in NOx-traps. However, they are mobile at high temperatures in the presence of steam, and react with cordierite substrate causing loss of the NOx storage component, and deterioration of substrate properties. Mitsubishi, ITC and NGK (2001-01-1298) reported three approaches to overcome these problems. The first was to retain alkali in the washcoat by reaction with an acidic component: a zeolite was chosen. The second approach was to protect the substrate with a silica pre-coat, and the third was to minimise sulfur accumulation by incorporaang titania in the washcoat Comb- all three modifications afforded a NOx-trap with improved overall thermal resistance.

Diesel NOx-Traps Diesel NOx-traps have special demands: diesel

engines operate at cool temperatures and are specifically designed to run lean, so obtaining rich regeneration conditions is a challenge. ASEC (2001-01-0508) described work conhrrmng that NOx-traps can be desulfated at 650°C and at an &:fuel ratio - 13. A programme involving FEV, National Renewable Energy Laboratory, MECA, Battelle, Ford, ASEC and Detroit Diesel examined desulfation of NOx-traps in diesel applications; finding NOx conversion efficiency could be restored. A NOx-trap aged for 250 hours running on 30 ppm sulfur fuel had its NOx conversion efficiency fully restored by a single desulfation. However, with repeated desulfations performance gradually decreased. The reason for this is unclear, but may be due to the regeneration procedure.

Diesel Particulate Filters Diesel engines run lean and have excellent fuel

economy, but removing particulate matter (Ph4) from the exhaust gas is difficult. Over recent years

Platinwm Met& h., 2001, 45, (2) 72

the amount of soot has been lowered dramatically through higher injector pressures, better fuel atomisation, and by improved fuel management and combustion control. However, it is generally thought that ‘clean diesel’ requires a Diesel Particulate Filter (DPQ, and the most common DPF is a ceramic wall flow filter.

Understandmg the fluid dynamics of DPFs was extended by presentations from Michigan Technological University, CERTH/CPERI and

0911) describing three flow mechanisms which contribute to pressure drop: filtration inertia losses, channel inlet contraction and channel exit expansion loses. Exit losses are dominant, being about twice those at the filter inlet The models estimate filter pressure-drop as a function of loac- ing and agree well with observations. The influence of inlet radial non-uniformity can lead to partial regeneration near the periphery. The practical challenge is to bum trapped soot without hgh temperatures damaging the filter.

One successful approach used low-temperature oxidation of soot with NO2 obtained by oxidising NO in the exhaust gas over a Pt catalyst In heavy- duty applications the temperature of the exhaust gas is usually high enough for this to occur. This system is known as the Continuously Regenerating Trap (CRT), or Continuously Regeneratiug Diesel Particulate Filter (CRDPF) and many thousands are installed on buses and trucks. Japanese/Finnish work (2001-01-1256) resulted in a procedure for increasing exhaust gas t e m p t u r e at low e q k e speed for CRT operation without fuel penalty.

Experience with a test fleet of heavy-duty diesel vehicles fitted with CRTs in Southern California was reported by Johnson Matthey, National Renewable Energy Laboratory, BP and West Virginia University (2001-01-0512). The fleet included school buses, fuel trucks, and delivery and transit vehicles. The CRTs worked well and reduced PM, CO and HC in the exhaust by 90 to 99%. No measurable impact on fuel economy was noted. New York Environmental Conservation, Johnson Matthey, Environment Canada, Equilon Enterprises and Coming (2001-01-0511) reported the performance and durability of CRTs on diesel

Coming (2001-01-0908, 2001-01-0909, 2001-01-

buses at New York City Transit. In this successful programme PM, CO and HC were reduced by over go%, carbonyls by more than 99%, polyaro- matic hydrocarbons (PAHs) by more than 8O%, and nitro-PAHs by more than 90%.

NGK reported a computer simulation for hgh temperature regeneration of wall-flow filters, and performed 2D thermal stress analysis for different filter designs. Their results showed that the max- mum temperature during soot combustion is moderated if the filter has high thermal mass and hgh thermal conductivity. These propemes are larger for silicon carbide (Sic) than for cordierite, and explains why Sic is gaining popularity in potential hght-duty diesel applications. Light-duty diesel vehicles have cooler exhaust gas than heavy- duty ones, and achieving high tempemtures for DPF regeneration has an undesirable impact on fuel consumption, so the reaction of soot with NO2 at moderate temperature is very beneficial. The regeneration of catalytic DPFs was discussed by Peugeot Citroen, dmc’ and the University of Siegen (2001-01-0907). They showed that having catalyst in the DPF can have a s m a l l benefit in reducing the soot combustion temperature.

Conclusions The integration of new advanced pgm-based

catalysts into total systems for emissions control is achieving extremely low tail-pipe emissions levels. Currently it appears that the role of platinum is becoming relatively more important. This trend could well continue. M. V. M l l G G

References 1 “Amilmced Cadyiic convertets and Substrates for

Combustion 2001” (SP-1574), “Diesel Exhaust Emissions Gmmk Deve@mnts in Regulation and Catalytic Systems’’ (SP-1581), “Diesel Exhaust Emissions Conmk Diesel Pactidate Fdters” (SP- 1589, “Djrect Injection SI Engule Technslogy 2001’’

Methods’’ (SP-1588), ‘‘GumaI Emissions Technology“ (SP-1590), ‘’Emission Conml Modeling“ (SP-1605) “F‘latinum”, Johnson Matthey, London, 2000 and www.platinum.matthey.com for details of platinum and palladium prices

Gasoline Emission S,tems’’ (SP-)573), ‘‘Advallces in

(SP-1584), ‘’Etni~Si~n~ M e a ~ ~ ~ m a t s and Test

2

Martyn Twigg is the European Technical Director of Johnson Matthey Catalytic Systems Division and is based in Royston.

PLzti#mMCtdr h., 2001,45, (2) 13

High Temperature Mechanical Properties of the Platinum Group Metals ELASTIC PROPERTIES OF PLATINUM, RHODIUM AND IRIDIUM AND THEIR ALLOYS AT HIGH TEMPERATURES

By Jurgen Merker* and David Lupton W. C. Heraeus GmbH & Co. KG, Hanau, Germany and Michael Topfer and Harald Knake Friedrich Schiller University, Jena, Germany

The platinum group metals are well suited for use at extremely high temperatures under mechanical loads and simultaneous corrosive attack. They have high melting points, excellent chemical stability and are highly resistant to oxidation. When using these materials in the design of components it is necessary to have data available on their elastic properties as a function of temperature. In this paper, investigations are presented into the temperature dependence of Young’s modulus, the modulus of rigidity and Poisson’s ratio for platinum, platinum alloys, rhodium and iridium. Measurements were carried out at the Friedrich Schiller University, Jena, using a resonance technique. Influences from both the microstructure and the alloying elements on the elastic properties and their temperature dependence were found.

Platinum group metals (pgms) and in particular platinum alloys are indispensable in many fields of indusaial application because of their outstanding physical and chemical properties. Components made from these materials are frequently subjected to extremely complex mechanical loadmg at hgh temperatures, often being simultaneously exposed to corrosive attack. A major aspect in the design of components to be used, for example, in the glass industry, in aerospace technology and in single crystal growing is to ensure optimum service life while using the least possible quantity of noble metal. In addition to data on the stress-rupture strength and creep properties (l), the design engineer requires values for the elastic properties of these materials up to very hlgh temperatures.

However, very little data on the temperature dependence of the elastic constants of the platinum metals and their alloys is found in the literature. Apart from the published ipvestigations (Z3), a current monograph gives the elastic properties of platinum alloys at room temperature (4). The elastic moduli of pure pgms as a function of temperature are given in the same publication (4) * now with KM Europa Metal AG, Osnabruck, Germany

with reference to work carried out by Reinacher in the 1960s (5-7), and published more recently (8). Comprehensive work on the temperature dependence of the elastic moduli of metals and alloys was published by Koster in the 1940s (9-11). However, in view of the state of technical development at that time, these results can only be regarded as a guide.

Experimental Procedure The resonance method used to determine the

elastic properties is a non-destructive, dynamic technique characterised by its lugh precision. It is applicable to all materials which can be stimulated to mechanical oscillation, see Figure 1. This state- of-the-art process is suitable for determining elastic constants of materials with isotropic, cubic or transverse-isotropic mechanical behaviour in a temperature range from -30°C to 1650°C (12-14). In order to derive these properties with a lugh degree of precision from the characteristic frequencies (of oscillation) on specimens using the resonance method, it is necessary to know the mathematical relationships between these quantities

Plalnum Metah b., 2001.45, (2), 7 4 4 2 74

Fig. I The elastic properties of metal and alloy samples determined at various temperatures in a high temperature furnace. The beam is supported on alumina knife-edges. Oscillations are generated with the aid of a network analyse,: transformed into mechanical oscillations by piezo sensors and transmitted to the beam via alumina Pbre couplers

as exactly as possible. The frequency equations derived from the basic theory of oscillating beams, which are commonly used for such evaluations, do not give the required accuracy. The necessary relationships can therefore only be derived on the basis of the known three dimensional Equation of motion from the linear theory of elasticity. Under the condition that the body is ideally elastic, homogeneous and isotropic, we derive for Young’s modulus (E) and Poisson’s ratio (v):

graddivu‘ ‘) 1 a z i E 1 -2v

where z i = displacement vector, p = density

The solutions of this system of differential equations must also fulfil the boundary conditions, that is: zero stress over the complete surface in the practical experimental arrangement.

If the partial spectra of only the torsional and longitudinal oscillations are evaluated, we obtain the frequency Equations:

Frequeny of tonional osciikations

with FT,, = 1 for circular cylindrical beams, G = modulus of rigidity, 1 = beam length, n = order

Frequency of hngitudinal oscihtions 7

(iii)

where the factor FLn for circular cylindrical beams is derived from the Equation:

-3 ’ (1 - 2v)(l + V)

(nKa)’ 1

(ka)’ = E.FL: 2(1 + V) - I] and E. = -

uo, /, are Bessel functions of the first kind, a =

If FLnf from Equation (iv) is developed into a radius)

power series in E,, we obtain:

wi thk ,= - -v ’ 1 and 2

[7 - 4v -32v2 + 4v’ + 24vq V’

48(1 - v? k2=--

Equation (v) thus obtained shows clearly the dependence of the factor F h on v and na/l which is caused by the couplug of the longitudinal and transverse oscillations (dispersion). However, it also shows that the accuracy of the basic theory (Fh 4) is insufficient and that the more precise

PlatinwmMetuLr Rnr, 2001,45, (2) 75

modelling permits the determination of Young’s modulus and Poisson’s ratio (vD) from a measured partial specaum of the longitudinal characteristic frequencies alone. The modulus of rigidity can be determined from the measured partial spectrum of the torsional oscillations accordmg to Equation (ii).

The temperature dependence of the elastic constants was determined in a h g h temperature furnace. The cylindrical sample beam is supported on alumha knife-edges, on the right of each diagram in Figure l. The oscillations were generated using a network analyser, transformed into mechanical oscillations via piezo sensors (on the left of each diagram) and transmitted to the beam via fine alumina fibre couplers. The oscillations of the sample are detected via a further alumina coupler attached to a second piezo sensor (not shown) and transmitted back to the network analyser for processing. The alumina fibre coupler is placed at the centre of the circular end surface of the sample if longitudinal oscillations are to be analysed Qft-

164.6 159.3 153.3 149.1 145.6 141.9 137.8

Y O U N e MODULUS. E.GPa MODULUS OF RIGIDITY, G , G b

0.396 0.389 0.401 0.403 0.406 0.409 0.396

POISSON’S RATIO, V

0.46

0.44

0.42

0.401

0.384 . . . . . . - 4 0 100 200 300 400 500 600 700 800 900

TEMPERATURE. *C

Fig. 2 Temperature dependences ofc (a) Young’s modulus, E, and the modulus of rigidity, G. for platinum; (b) Poisson’s ratio, v, for platinum. The value vD was determined from the dispersion of the characteristic longitudinal frequencies: while vuc was determined from the relationship vWG = E/(2G) - I

Table I

Temperature Dependence of the Elastic Properties E, G and v for Platinum

T, “C I E, GPa I vD I G, GPa

25 200 400 500 600 700 800 900

, jl 48.9 47.7

0.518 0.506 0.500 0.491 0.489 0.487 0.479

hand diagram) or at the circumference of the end surface for torsional oscillations (right-hand diagram). The resonant frequencies and the half-peak width of the amplification function (determining dampmg) can be recorded. The sample beam requires time to achieve a stable temperature between measurements to avoid errors.

The elastic constants, Young’s modulus E, the modulus of rigidity G and Poisson’s ratio v were measured on platinum, iridium and rhodium and on alloys of platinum with 10,20 and 30 weight per cent of iridium and rhodium at both room temperature and elevated temperatures, by the resonance method. Poisson’s ratio, V, was determined as VD from the dispersion of the characteristic longitudinal frequencies and also as vE/G from the relationship VE/G = E/(2G) - 1. If the two values are the same the sample is isotropic or quasi-isoaopic. All the materials could be measured at temper-

atures where the loss factor of internal friction (damping), d, was not greater than 10”. At higher values of loss factor it was not possible to determine the resonance point reliably from the amplification function*.

Elastic Properties of Platinum Measurements with reproducible results were

possible up to 800°C and in the case of repetition up to 900°C. Both Young’s modulus and the modulus of rigidity of platinum show a steady decrease with increasing temperature, see Figure 2. This is

*See h t t p : l / ~ . . u n i - j n d e / m i t / ~ ~ ~ h ~ / ~ t = ~ ~ . h ~ l for huther informntion.

P h h n m Met& Rm, 2001, 45, (2) 76

modelling permits the determination of Young’s

partly in contrast to earlier determinations (2, 20) which showed a steady decrease in Young’s modulus from 174 GPa at room temperature to 168 GPa at 400°C during a hrst measurement, followed by a decrease to 146 GPa at 500°C and then a steady decrease to 135 GPa at 700°C. This effect was found to be irreversible. Repeat measurements showed a Young’s modulus of 155 GPa at room temperature which decreased continuously to 127 GPa at 800°C. The current measured values given in Table I were determined on as-cast platinum rods, and show relatively good agreement with the repeat determinations and with values measured at temperatures 2 500°C (2). The irreversible decrease in Young’s modulus found in the earlier work was apparently due to a deformation structure in the material which was removed by recrystallisation during the measurement.

It is interesting thar the values of Young’s modulus determined at room temperature on the specimen with the apparently deformed structure correspond reasonably well with the values in the literature (4,9, 16), whereas the values determined on platinum in the recrystallised state (155 GPa) and the as-cast state (165 GPa) are lower. Furthermore, Young’s modulus was found to be dependent on the purity of the platinum. On undeformed specimens, the following values were determined: 169 GPa with 99.99% Pt, 172 GPa

T, “C

25 200 400 500 600 700 800 900

1000 1100 1200

Table II

Temperature Dependence of the Elastic Properties E, G and v for Forged Rhodium

E, GPa

372.4 355.8 332.1 321.4 310.4 299.4 291.0 281.6 271.5 260.6 246.9

VD

0.266 0.268 0.267 0.274 0.278 0.282 0.287 0.293 0.296 0.294 0.296

G, GPa

151.7 144.3 134.2 129.5 124.7 120.3 116.2 111.9 107.3

0.233 0.237 0.241 0.245 0.246 0.252 0.258 0.265

YOUNG’S MODULUS. E.GPa MODULUS OF RIGIDITY. G,GPa . .

,150 30

380-

360‘

340.

320. .130

300.

280.

2 60.

~140

240J

POISSON‘S RATIO. V 0.300-

0.29.

0.28-

0.27-

0.24

0.23

0.224 . . . . . . . . . . . 1 0 loo 200300400500500700800900X)OOo01200

TEMPERATURE, ‘C

Fig. 3 Temperature dependence o$ (a) the elastic properties E and G for forged rhodium (b) Poisson’s ratio for forged rhodium

with 99.95% Pt and 177 GPa with 99.9% Pt. The value for Poisson’s ratio determined from

the dispersion of the longitudinal charactehtic frequencies VD is approximately constant over the whole temperature range, whereas the value of Poisson’s ratio determined from the elastic moduli vE/G decreases shghtly with increasing test temperature. The difference between VD and v ~ / G indicates some influence from anisotropy which may be related to the primary solidification structure.

Elastic Properties of Rhodium At room temperature, Young’s modulus for

rhodium (373 GPa to 384 GPa (2)) is considerably %her than that for platinum. With increasing temperature Young’s modulus decreases in an approximately linear manner to 280 GPa (at lO0OoC) (2) and 248 GPa (at 1200°C). The modulus of rigidity also shows a linear decrease with increasing temperature.

A comparison of the current measurements, also carried out on forged and subsequently machined rhodium rods Fable I1 and Figure 3), and earlier

P/alnwn Metu.!r b., 2001,45, (2) 77

investigations (2) shows that for Young's modulus, the earlier measurements are reproducible at about 10 GPa lugher than current values. The earlier values for Poisson's ratio VD and v E / ~ differ by only about 5 per cent (2), while in the current measurements the difference is 12 to 15 per cent- This means that the anisotropy is significantly less for those samples with the &her Young's modulus. This difference is presumably related to the fact that the earlier samples (2) were more severely deformed by forging because a larger ingot size had been used. The values for Young's modulus given in the literature (4, 7) also indicate that the microstructure is relatively severely deformed.

Elastic Properties of Iridium Iridium has the highest Young's modulus of all

face-centred cubic metals and the whes t modulus of rigidity of all metals. The elastic properties E, G, VD and vE/G measured on iridium in the as-cast state are summarked in Table III. Young's modulus and the modulus of rigidity decrease linearly from room temperature with increasing temperature, see Figure 4. At 1000°C the modulus of rigidity was sti l l 170 GPa and Young's modulus 41 7 GPa. Young's modulus could be measured up to 1300°C (382 GPa).

The values for Poisson's ratio VD and VE/G

Table 111

Temperature Dependence of the Elastic Properties E, G and v of As-cast Iridium

T, "C

25 200 400 500 600 700 800 900

1000 1100 1200 1300

- E, GPa

525.5 507.4 483.6 472.7 461.2 450.5 439.9 429.5 417.5 406.1 394.4 384.2

VD

0.254 0.260 0.261 0.265 0.268 0.271 0.275 0.279 0.281 0.279 0.286 0.309

G, GPa

21 8.2 209.9 199.4 194.3 189.5 184.5 179.7 174.9 170.3

VElG

0.204 0.209 0.21 3 0.21 6 0.21 7 0.221 0.224 0.228 0.226

YOUNG3 MODULUS, E,GPa MODULUS OF RIGIDIlY, G.GPa

4a

480

460

420\ 400 \\

- 210 -200

.190

.re0

38OJ \ 17

POISSON'S RATIO, V

0

0.30 1 0.29 *"/I

0.24 0.25 1 -

TEMPERATURE, .C

Fig. 4 Temperature dependence 08 ( a ) the elastic properties E and G for as-cast iridium (b) Poisson's ratio for as-cast iridium

increase with increasing test temperature. The difference between the two values was about 18 per cent. This indicates marked anisotropy associated with the primary as-cast microstructure. A comparison of these results with previous investigations (2) shows that deformation by hot rolling leads to somewhat lugher values for Young's modulus (I~RT = 532 GPa, ElmC = 424 GPa) and the modulus of rigidity (GT = 223 GPa, Glwc = 173 GPa).

These prior values correspond relatively well with data from the literature (4, 9, 16). However, although the increase in Poisson's ratio with increasing temperature measured by both sets of investigations corresponds qualitatively fairly closely, more substantial discrepancies are determined between VD and vE/G (- 35 per cent), thus indicating a high degree of anisotropy caused by the deformation microstructure from the hot r o w .

Elastic Properties of Platinum-Rhodium Alloys

The elastic properties E, G, VD and vE/G determined for alloys Pt-lO%Rh, Pt-20YoRh and Pt30%Rh as a function of temperature for sped-

Plptinum Met& Rm, 2001,45, (2) 78

I Table IV

Elastic Properties E, G, vD and vYG for As-cast Platinum-Rhodium Alloys at Selected Temperatures

I Pt-1 O%Rh I Pt-20YoRh

T, ‘C E, GPa

25 212.6 200 206.3 400 197.9 500 193.3 600 188.7 700 183.9 800 179.2 900 175.0

1000 169.7 1100 164.9 1200

- VD

- 0.365 0.368 0.372 0.376 0.376 0.378 0.379 0.383 0.381 0.385

-

- G,

G Pa - 78.0 75.4 72.1 70.5 68.7 66.9 65.2 63.4

-

VYG E, vo G, GPa G Pa

0.363 245.9 0.342 91.6 0.368 236.6 0.346 87.8 0.372 224.7 0.351 83.3 0.371 218.8 0.353 80.9 0.373 213.0 0.355 78.6 0.374 207.2 0.358 76.3 0.374 201.0 0.359 74.1 0.380 195.5 0.360 72.0

189.8 0.362 69.8 184.6 0.367 67.7 179.2 0.380

I I I

- VYG

- 0.342 0.347 0.349 0.352 0.355 0.358 0.356 0.358 0.360 0.363

- E,

GPa

277.7 265.7 251 .O 243.9 236.6 229.5 222.1 215.7 209.3 202.8 195.4

-

PtdO%Rh

vo G, G Pa

0.324 104.8 0.330 99.9 0.334 94.0 0.338 91.1 0.340 88.2 0.343 85.5 0.345 82.7 0.346 80.0 0.350 77.5 0.352 74.7 0.358

I I I

0.325 0.330 0.335 0.339 0.341 0.342 0.343 0.348 0.350 0.357

mens in the as-cast condition, are presented in Table IV. Young’s modulus and the modulus of rigidity decrease linearly with increasing temperature, see Figures 5a and 5b. The values for Poisson’s ratio VD and VE/G show only slight differences which become n e w b l e at hgh rhod- um concentrations, Figure 5c. In contrast to the large discrepancies found for the pure metals, these small differences may be due to the influence of solid solution formation during the development of the primary cast microstructure. The damping showed maxima in

POISSON’S RATIO, V 0.39

0.38

0.37

0.36

0.35

0.34

0.33

0.32

0 .a 0 100 200 300 400 500 W O 700 800 900 loo0 1100 1200

TEMPERATURE, *C

Fig. 5 Dependence 03 (a ) Young’s modulus on temperature for as-cast Pt-Rh alloys (b) the modulus of rigidity on temperature for as-cast Pt-Rh alloys ( c ) Poisson’s ratio on temperature for as-cast Pt-Rh alloys

P.&immMe&Rcv., 2001,45, (2) 79

2000

1800 1769%

6;

w‘ 1200.

L 800.

a $ 1000, LL

I 600.

400.

200.

1400 P

I

10 20 30 40 50 60 70 80 90 Pt RHODIUM CONCENTRATION, M% Rh

1800

1600 J1769.C

1370.C F q 1400

Tripathi-

800 600

200

10 20 30 40 50 60 70 80 90 100 IRIDIUM CONCENTRATION, wt.%

Fig. 6 Phase diagram of the binary systems: (a) Pt-Rh system (17); (b) Pt-lr system (17, 20)

YOUNG’S MODULUS. E. GPa

1304 I 0 10 20 30

RHODIUM CONCENTRATION, M.’h

Fig. 7 Dependence of Young’s modulus on rhodium content for as-cast Pt-Rh alloys at various temperatures

specific regions for the various alloys. This indicates a miscibility gap in the binary Pt-Rh system similar to that shown in Figure 6 (17).

The higher values in the literature for Young’s modulus at room temperature (4, 18) have a high

probability of being attributable to prior deformation of the specimens. Figure 7 shows the effect of rhodium content on Young’s modulus of specimens in the as-cast condition at various test temperatures. The greatest effect on Young’s modulus due to rhodium additions is observed for concentrations of up to - 10 weight per cent. The rate of increase is less marked at hgher rhodium contents. A similar effect has been found for the stress-rupture strength of Pt-Rh alloys (19).

Elastic Properties of Platinum-Iridium Alloys

The elastic properties E, G, VD and VE/G determined on specimens of as-cast alloys Pt-lO%Ir, Pt-2O0/oIr and Pt-3O0/oIr are shown in Table V as functions of temperature. Young’s modulus and the modulus of rigidity decrease linearly with increasing temperature, see Figure 8. The differences between the values for Poisson’s ratio vD and VE/C; are somewhat greater for the Pt-Ir alloys

Fig. 8 Dependence of: (a) Young’s modulus on temperature for as-cast Pt-lr alloys; (b) the modulus of rigidiry on temperature for as-cast Pt-lr alloys

PIatnnm Met& Rcv., 2001,45, (2) 80

Table V

Elastic Properties E, G, vD and vYG for As-cast Platinum-Iridium Alloys at Selected Temperatures

G, G Pa

97.5 93.6

~ 88.6 86.2 83.9 81.5 79.3 76.9 74.7 72.5

- T, ‘C -

25 200 400 500 600 700 800 900

1000 1100 1200 1300 1400 -

VO

0.368 0.368 0.371 0.373 0.379 0.378 0.384 0.378 0.386 0.387 0.386 0.393

Pt-1 O%lr

G, GPa

85.5 82.2 78.2 76.2 73.9 71.9 70.1 68.2 66.2 64.1

E, G Pa

202.3 196.6 188.3 183.9 178.8 173.6 170.7 166.4 162.2 157.1

VYG

- 0.378 0.382 0.382 0.385 0.381 0.381

VD G, GPa

0.378 73.4 0.382 71.1 0.382 68.1 0.384 66.4 0.381 64.8 0.382 62.8 0.389 58.1 0.391 0.396 0.400

- E,

G Pa

233.3 224.8 214.3 209.0 201.6 196.2 192.3 186.9 182.5 176.9 171.1 165.0

-

-

Pt-PO%lr I Pt-30% Ir - V E ~ G

- 0.364 0.367 0.370 0.371 0.364 0.364 0.372 0.370 0.378 0.380

- E,

G Pa

263.3 253.6 240.8 234.7 228.5 222.5 216.1 21 0.2 204.5 198.5 192.2 185.3 176.8

- vn

0.346 0.351 0.354 0.356 0.358 0.361 0.359 0.363 0.368 0.368 0.372 0.374 0.375

V E ~ G

0.350 0.352 0.359 0.361 0.362 0.365 0.363 0.367 0.369 0.369

than for the Pt-Rh alloys. At this stage, it is not clear why the difference for Pt-20YoIr is so large. The behaviour of the Pt-Ir alloys also indicates a maximum in damping corresponding to the miscibility gap (Figure 6b (17, 20)). This maximum was more dearly distinguished than that found in the Pt-Rh system.

In Figure 9 the influence of the iridium content on Young’s modulus at various test tempera-

POISSON’S RATIO, V 0.40

0.39

0.38

0.37

0.36

0.35

0.34 . 0 1 0 0 200 300 400 500 600 700 800 900 1WOilW 1200 1300

TEMPERATURE, *C

tures is shown for as-cast Fig. 8(c) Dependence of Poisson S ratio on temperature for as-cast Pt-lr alloys specimens. The modulus increases nearly linearly with iridium content up to 30 weight per cent. Comparing values for Young’s modulus shows generally good agreement with results of prior investigations (2) and data from the literature (4, 18). The relatively small discrepancies are attributable to different processing conditions.

Conclusions The results of investigations carried out using

the resonance method show that Young’s modulus and the modulus of rigidity of platinum, rhodium and iridium and various platinum alloys in the

YOUNG’S MODULUS, E, GPa

130 I 1 0 10 20 30

IRIDIUM CONCENTRATION. wt.%

Fig. 9 Dependence of Young 5 modulus on iridium content for as-cast Pt-lr alloys at various temperatures

Pbtinnm Metah Rey., 2001,45, (2) a1

as-cast condition decrease linearly with increasing test temperature. The gradients of the lines are dependent on the compositions of the alloys.

The microstructural state of the material resulting from prior deformation influences in particular the magnitude of Young’s modulus and the anisotropic behaviour of Poisson’s ratio. Poisson’s ratio is also influenced by the state of the primary as-cast microstructure.

A marked increase in damping was observed in the regions of the miscibility gaps. This suggests that the resonance method could be a sensitive technique for determining miscibility gaps in materials which can be subjected to mechanical oscillations and whose basic damping, d, is less than (21). Further microstructural and crystal- lographic investigations are required to confirm these correlations.

References 1 B. Fisher, A. Behrends, D. Freund, D. F. Lupton

and J. Merker, P&nm Metuh h., 1999,43, (l), 18 2 D. F. Lupton, J. Merker and B. Fischer, 3rd

European Precious Metals Conf., Florence, Italy, 17-19 September, 1997, Eurometaux, Brussels

3 J. Merker, D. F. Lupton, W. Kock and B. Fischer, 18th Int. Congress on Glass, San Francisco, U.S.A., July 510,1998

4 Degussa AG (ed.), “Edelmetall-Taschenbuch”, Huh-Verlag, Heidelberg, Germany, 1995

5 G. Reinacher, “Iddium”, eds. E. Rabald and D. Behrens, Dechema-Werkstoff-Tabelle, “Physkalische Eigenschaften”, Frankfurt, 1966

6 G. Reinacher, “Platin-Plathlegierungen”, op. cit., (Ref. 5)

7 G. Reinacher, “Rhodium”, op. it., (Ref. 5) 8 M. Winter, The Periodic Table on the website

http://www.webelements.com/, University of Sheffield, England

9 W. Koster, Z. Met&, 1948,39, 1 10 Koster and W. Rauscher, Z. Metdkd, 1948,39,111 11 W. Koster, Z. Met&., 1948,39,145 12 H. Knake, W. Meuche and H. Reichardt, Wir.r. Z. d

Fnkb icb -ScW-UeW Jena, Math-N&s.-Re&e, 1981,30, (6), pp. 955-960

13 H. Knake, H. Reichardt and M. Topfer, ap. cit., (Ref.

14 A. Jordanov and H. Knakc, Deutsche Gesellschaft fiu zerstorungsfreie Priifung, 1996,55, pp. 9-16

15 H. Knake, S. Schiissler and M. Topfer, Versuchsanleiw Ermittlung elastischer Kennwerte (Expedmental Guide: The Determination of Elastic Properties), Dept of Applied Mechanics, Technical Institute, Friedrich Schiller University of Jena

12), pp. 949-953

16 TAPP Database, E. S. Microware Inc., Hamilton, OH, 1991

17 T. B. Massalski (ed.) et ul, “Jjinary Alloy Phase Diagrams”, 2nd Edition Plus Updates, ASM International, Ohio/National Institute of Standards and Technology, 1996

18 F. Aldinger and A. Bischoff, in “Festigkeit und Verformung bei hoher Tempera&, B. Ilschner (ed.), DGM-Informationsgesellschaft, Oberursel, Germany, 1983, pp. 161-195

19 D. F. Lupton, J. Merker, B. Fischer and R. Volkl, 24th Annual Conf. of International Precious Metals Institute, Williamsburg, USA., 11-14 June, 2000

20 S. N. Tripathi and M. S. Chandrasekharaiah, J. Less- Common Met., 1983,91,251

21 H. Knake and M. Topfer, Thiiringer Werkstofftag of the Technical University of Ilmenau, 15 March 1999

The Authors Jiirgen Merker was a Development Project Manager with W. C. Heraeus GmbH & Co. KG until May 2000. His main activities were in the processing and characterisation of platinum materials and the pgms for high temperature applications.

David Lupton is a Development Manager of the Engineered Materials Division with W. C. Heraeus GmbH & Co. KG. He is particularly involved in the metallurgy of the pgms, refractory metals and other special materials.

Michael Topfer is a Technical Research Assistant in the Technical Institute of the Friedrich Schiller University of Jena. His major field of interest is the determination of material properties by dynamic oscillation techniques.

Harald Knake is Professor of Applied Mechanics at the Friedrich Schiller University of Jena and specialises in the elastic properties of materials

Ruthenium-Initiated Star Polymers Star-shaped polymers are attracting interest as

polymeric materials because of their unusual structures. Such structures can be made by living polymerisation processes, one of which involves a hkmg reaction using living linear polymers and divinyl compounds.

Researchers at Kyoto University in Japan now report a multi-arm star-shaped polymer with a cross-linked microgel core (K-Y. Baek, M. -to and M. Sawamoto, Mmmokmks, 2001, 34, (2), 215-221). Using in-sib polymerisation of methyl methacrylate (MMA), a halide initiator and RuCl@’Ph$3, in the presence of Al(Oi-Pr)J a living poly(MMA) was formed which on reaction with a divinyl compound resulted in star-shaped polymers.

The yield depended on the structures of the initiators, divjnyl compounds, monomers and other reaction conditions. The best system gave a polymer of about 20 poly(MMA) arms per molecule.

P U n m Metah Rm, 2001, 45, (2) 82

Commercial Heterogeneous Catalysis HANDBOOK OF COMMERCIAL CATALYSTS - HETEROGENEOUS CATALYSTS BY HOWARD F. RASE, CRC Press LLC, Boca Raton, 2000,488 pages, ISBN 0-8493-9417-1, US. $139.95, f94

In this book, Professor Rase has set about the gargantuan task of describing many of the commercial processes which employ a heterogeneous catalyst. His main aim has been to enable chemists or chemical engineers to gain background information quickly on a particular process. In the main he has been very successful in the compilation of a concise and highly readable book which addresses reactions as diverse as hydrogenation, oxidation, dehydrogenation, alkylation, epoxidation, isomerisation, petroleum refining and synthesis gas chemistry.

The book is divided up into 19 chapters, each of which describes a particular type of reaction and contains a comprehensive reference section to direct the interested reader to pertinent review arti- des. The chapters are subdivided into sections deallng with the overall reaction chemistry indud- ing any thermodynamic constraints associated with it. Subsequent sections deal with the favoured catalysts for the reaction, the sources of deactivation and methods for regeneration of these materials as well as their suppliers and licensors of the processes. Details of the catalytic reactors used are considered as are the reaction kinetics. Some quite detailed drawings of the various reactors for these indusmal-scale processes are given in a final appendix. This is possibly more beneficial for a chemist than an engineer! The index is arranged so that the reader can search for the relevant section by reactant or product.

The book shows clearly the wide range of reactions, which are catalysed efficiently by supported platinum group metals ( p g m s ) materials. In many cases the supported pgm is not unique in its ability to catalyse the reaction, but its superior activity and selectivity is sufficient to outweigh the cost considerations. For example, many exothermic hydrogenation reactions can be catalysed by nickel but operation of a more active supported platinum or palladium catalyst at lower reaction temperature will bring obvious thermodynamic benefits.

This can be illustrated by a reaction such as the hydrogenation of benzene to cydohexane where the supported pgm catalyst has sufficient activity to allow short contact time between the reactant and the catalyst. This minimises the extent to which the thermodynamically favoured but kineti- cally slow hydroisomerisation reaction occurs. This reaction produces the unwanted methylcyclopen- tane side-product.

Operating this process at low temperature also helps avoid the highly exothermic cyclohexane hydrocracking reaction, which can cause thermal runaway in the reactor. Temperature excursions can be minimised using three or four adiabatic fixed bed reactors with interstage cooling. Temperature can be further controlled by the use of a lower activity catalyst in initial beds. Alternatively, non-adiabatic multitubular reactors where the heat of reaction is absorbed by a cooling fluid in the shell side of the reactor can be used.

The half century experience of the author is evi- dent in his astute treatment of the kinetics of these processes. The benzene hydrogenation reaction is very suited to kinetic analysis as it is dominated by a single reaction and has been shown to be zero order in benzene. However, in hgh temperature reactions such as the dehydrogenation of ethylbenzene or lower alkanes where rapid coke formation results in catalyst deactivation, the author stresses that basing an industrial model on intrinsic kinetics of the desired reaction is 'futile'. He suggests that an empirical rate expression as a function of time- on-stream, which includes a deactivation term, would be more appropriate.

This book is a very useful reference tool for any chemist or engineer workmg in the area of heterogeneous process catalysis and Professor Rase is to be commended for succinctly compiling so much information. M. HAYES

Martin Hayes is a Senior Chemist, Process Catalyst Development Department, Johnson Matthey, Royston. He is interested in the development of heterogeneous platinum Qroup metals catalysts for commercial production of added value chemicals.

Phtinrcm Metals Rm, 2001,45, (Z), 83 83

Alloy Structures of the Ti-Ni-Ru System in the Ti-TiNi-TiRu Composition Range By E. L. Semenova and N. Yu. Krendelsberger I. N. Frantsevich Institute for Problems of Materials Science, NAS of Ukraine, 3, Krzhyzhanovsky str., Kiev, 03142, Ukraine

Interest in the alloys of the titanium-nickel system is due to their attractive properties: the high strength of nickel-based alloys, the ability of intermediate phases based on Ti2Ni and TiNi to undergo amorphisation and hydrogen absorption, and the thermoelasticity of TiNi-based alloys. li-Ni alloys are resistant to oxidation and corrosion in most mild corrosive environments, and are used in chemical, medical and engineering applications. Here, we report on alloys in the Ti-TiNi-TiRu composition range of the Ti-Ni-Ru system, where ruthenium additions produce some interesting effects. Using phase diagrams and experimental results, the constituents of high temperature alloys and alloying processes are discussed.

An important aim of modem metals science is to create new alloys with specific properties. The interest in the ternary and multicomponent alloys of the titanium-nickel (Ti-Ni) system lies in their properties: high strength nickel-based alloys, intermediate phases based on Ti&i and TiNi which undergo amorphisation and hydrogen absorption, and thermoelasticity in TiNi-based alloys. Ti-Ni alloys are resistant to oxidation and corrosion, so are used in chemical plants, medical devices and equipment, and underwater engineering.

However, when ruthenium is added to titanium- based alloys and intermediate phases of the Ti-Ni system, the resulting Ti-Ni-Ru ternary alloys show superior corrosion properties (1). Ruthenium- enhanced a, a+P, and p titanium alloys display hgh corrosion resistance in dilute acids and hot brine environments (2). Ad- ruthenium to some nickel-containing steels improves their corrosion resistance (3). Such ternary alloys may be able to improve on other characteristics of the binary alloys.

In studying alloy properties and in developing new materials, information on phase diagrams is needed. Phase diagrams help in interpreting properties and may contribute to understanding process mechanisms, such as corrosion. They also allow properties to be correlated with alloy composition and temperature. Here, we examine the Ti-TiN- TiRu system and report some exciting effects due to ruthenium. As the number of published papers

on ruthenium seems to be growing (4), we hope this paper will contribute to the interest, and help in the search and development of new materials.

Information on the Ti-Ni-Ru system is frag- mentary and contradictory. Our earlier studies of ternary Ti-Ni-Ru alloys along the TiNi-TiRu section showed that TiNi and TiRu form a continuous solid solution at the subsolidus temperatures (5,6). We believe this will affect many aspects of the Ti- Ni-Ru phase diagram. Taklng the solid solution between TiNi and TiRu into account, the phase equilibria in the Ti-Ni-Ru ternary system are expected to be different from those which would occur if the TiN-TiRu section was peritectic (7, S), although interpreting the TiN-TiRu system as peritectic is inaccurate (5). Phase diagrams of the Ti-Ru and Ti-Ni binary boundary systems up to 50 at.% Ni are well known (9), the main features are:

Ti-Ru System The equiatomic phase (8) in the Ti-Ru system

has a CsC1-type cubic crystal structure and ciystallises from the melt at 2160 f 50°C. It is stable down to room temperature. It is homogeneous over the range 45 to 51 at.% Ru at 1575°C.

The P-phase, based on titanium, ciystallises from the melt into alloys which can contain up to 24 at.% Ru. In the range - 24-45 at.% Ru the p- phase is formed by peritectic reaction, at 1575"C, and coexists as a solid with the &phase (p+@

Pkatirim Metah Rm, 2001,45, (2), 84-91 84

- 1 at.%, the product of the reaction is P-phase in solid.

Ti-Ni System The TiN-based &phase crystallises from the

melt at 1310°C. The titanium solubility in the 6- phase is < 1 at.%. The phase based on T i a i (q) is formed by the peritectic reaction 8+L tj q at 984°C. L is liquid at peritectic point pz (- 31 at.% Ni). The q-phase forms a eutectic with the p- phase at 942°C. At the eutectic point, el, the alloy contains - 24 at.% Ni. Nickel solubility in titanium is - 10 at.% at the subsolidus temperature.

Production of the Ti-Ni-Ru Phase Diagram Starting materials for the synthesis of the Ti-

Ni-Ru alloys were: ruthenium powder (99.95 mass?h), nickel (99.99 massyo) and iodised titan- um (99.98 massyo). Alloy preparation and surface etching have been described (2). The alloys were

annealed at subsolidus temperatures, 900 to 930"C, and as-cast and annealed specimens were studied. The electron microprobe analysis method (EMPA) was used to determine the composition of the conjugated phases, besides the investigations mentioned in (5).

Results and Discussion From our investigation on Ti-Ni-Ru alloys, new

data on phase equilibria in the system at subsolidus temperature and on alloy crystallisation were obtained first.

No ternary compounds were found in the Ti- Ni-Ru system, so the equilibria in the system are determined by intermediate phases based on compounds in the binary boundary systems and solid solutions based on the components. The vertical section between the TiNi and TiRu equiatomic compounds (isopleth) for 50 at.% Ti is quasibina- ry and allows the Ti-Ni-Ru system to be triangulated into two thermodynamically indepen-

85

However, at 24-25 at.% Ru, an interval of

I Table I

Alloy composition, at.%

Ni Ru

10 20

20 5

20 10

30 10

I Alloy Phase Composition and the Solidus Temperature I Primary Heat treatment Phase Solidus Lattice parameters, phase composition temperature, nm

Tool, "C Temp., Time, P rl 6

T, "C h a a a

930 5 6 900 24 S+P+rl 980 0.315 1.131 0.306

P 900 20 P+rl 975 0.318 1.133 - 930 24

- 0.315 1.131 0.306 6 900 24 6+P+rl

6 900 28 6+rl

930 5

980 - 1.130 0.305

dcnt subsystems: Ti-Tli-Tau and Tli-Ni-Ru-Tfiu These two subsystems can be treated separately;

the Ti-TiNi-TiRu subsystem is discussed here. Solidus and liquidus surface projections ( F i i e 1). based on experimental results (such as Figures 2 and 3 and Tables I and II), an isopleth ( F i i e 4) and a crystallisation scheme for the Ti-TiNi-TiRu alloys (Figure 5) have been constructed. The isothermal section at 700°C F i e 6) is based upon experimental data at subsolidus temperatures, theory and data from the literature. Phases existing at solidus temperatures are described in Table I.

Solirliis Siirface of the Ti-TiNi-TiRu Subsystem There is a wide range fhitanium-based solid

solution at solidus temperature (Figure 1). The solubility of nickel (maximum - 10 at.%) in titanium

depends weakly on the ruthenium content up to the 7.4Ni-18Ru alloy; after this it sharply decreases towards the binary Ti-Ru system, to the alloy containing about 25 at.% Ru, which is the maximum solubility of ruthenium in titanium.

The solidus temperature of the P-phase decreases through the mutual ruthenium/nickel solution from 1670°C (melting point of Ti) to 1575°C in the Ti-Ru binary system, then decreases again to 980°C in the ternary system to the 7.4Ni- 18Ru alloy, which is a vertex of the G+P+q-phase triangle. Further decreases in the ruthenium content in the P-phase (towards the binary Ti-Ni system) result in the solid solution temperature dropping to 942"C, the temperature of the eutectic reaction L t) P+q here.

Titanium solubility in the &phase increases

b40.C I

f Qeo-c

Fig. 2 DTA curves of titanium alloy 1ONi-2ORu (6+q+P) and reference alloy 2ONi-8OTi (q+P). On heating, melting begins at - 940°C for 20Ni-807i, and near the peak qf the curve for IONi-2ORu; at 1010°C solid-liquid state wartiom end On cooling, crystallisation begins at - 1020°C for IONi-2ORu and at - IO00"C for 2ONi-8OTi. At 980 and 950°C respectively, the solid- liquid reactions end. At 700 (2ONi-8OTi) and 755°C. solid state reactions occur for Ti-based alloys

Ph%imm Met& Rm, 2001,45, (2) 86

I Table II

Alloy composition, at.%

Ni Ru

10 20 20 5 30 10

Composition of Phases at the Solidus Temperature in the Ti-TiNi-TiRu System

Coexisting phases Phase composition, at.%

P 6 II Ni Ru Ni Ru Ni Ru

7.4 i a 7 37 30.5 1 - 30.5 1 7 12

- 27 20 32 1 - 6+P+rl

P+II t1+6 -

gradually as nickel is replaced by ruthenium. The upper titanium border of the &phase in the ternary Ti-Ni-Ru system connects the points of the 5OT-5ONi alloy and the 45Ru-55Ti alloy of the Ti-Ru binary system, corresponding to the max- mum titanium solubility in Ti-Ru at subsolidus temperature (Figure 1). The solidus temperature of the &phase at the Ru-rich side is the lowest (980°C) at composition 7Ni-37Ru which is anoth- er of the vertices of the P+q+&phase tnangle, see Table 11.

In conformity with the solidus surface of the 6 and P single-phase fields, a sharp fall was observed in the temperature of the P+6 ruled surface from 1575°C (the temperature of the peritectic horizontal in the binary Ti-Ru system) to 980°C (the solidus temperature of the 6+p+q alloy).

As the p+q alloy composition moves away from the side of the P+q+6 tie-he triangle towards the Ti-Ni face, the temperature of the p+q ruled surface drops. Comparable differential thermal analysis (DTA) data obtained for alloys from the p+q+6 region and from the binary Ti-Ni system confirm this (Figure 2). As Figure 2 shows, the binary alloy starts to melt at - 940°C. For the ternary alloy the onset of melting is near the peak of the curve but cannot be determined accurately because of the superimposition of thermal effects. At 1010°C the solid-liquid state reactions end.

Microprobe analysis of the annealed 20Ni-5Ru alloy (Figure 3a) show the compositions of the conjugated phases (ltght grains are q-phase, dark grains are p-phase) and indicate that the solubility of ruthenium in the q-phase does not exceed 1 at.%, while the solubility of nickel in the P-phase

is - 3 at.% smaller than in the Ti-Ni binary system. The temperature drops very slowly along the

tie-lines that envelop the L+q+6 three-phase volume.

As mentioned before, the solidus temperature of the three-phase alloys, P+6+q, is 980°C (Figure 1). The coordinates of the vertices of the tie-line triangle around the solidus surface of the p+6+q phases are shown in Table II.

Thus the solidus surface of the Ti-TiNi-TiRu subsystem is formed by surfaces of three solid solutions based on p-titanium and on two intermediate phases (q and s>, by three ruled surfaces that terminate the two-phase solid regions (q+& S+p, P+q) and by the plane of the tie-line triangle (P+6+rl).

Liquidus Surface of the Ti-TiNi-TiRu Subsystem The liquidus surface of the Ti-TiNi-TiRu sub-

system consists of three surfaces of primary crystallisation of 6-, r\- and P-phases.

The &phase has the largest area, showing an extended range of concentrations; it has the largest region of primary crystallisation, bounded by pIUp2 (Figure 1). Microstructures of as-cast alloys from this region (Figures 3b, 3c and 3d) show the &phase displays coarse grains of varying composition in a dark ma&. The dark mattix is a mixture of phases that form on further cooling the ingots.

The microstructure of the 3ONi-1ORu alloy (Figure 3b) shows that the incongruent reaction of q-phase formation which took place in the Ti-Ni binary system is retained in the ternary system. hght grains of the &phase can be seen, with signs of a peritectic reaction along theix edges resulting in

Pkdinum Mekrls h., 2001,45, (2) 87

the formation of the q-phase (grey matrix). The q- phase lies between the &phase and liquid frozen in the very small (dark) interdendritic spaces.

The primary crystallisation of the &phase in the 20Ni-1ORu alloy (Figure 3c) is followed by common freezing of the P- and q-phases, according to

four-phase invariant reaction: L+6 H P+q. In Figure 1, the region of primary P-phase crys-

tallisation is shown by the borders or monovariant curves: Up, and Ue,. The incongruent reaction of P-phase formation which takes place in the Ti-Ru binary system is retained in the ternary system - up to alloy composition - 7N-l8Ru, then (in the ternary system) the character of the P-phase crystallisation changes to a congruent one. The evidence for this is the different shape of the den-

Fig. 3 SEM microstructures of the E-TiNi -ERu alloys: (a) 2ONi-SRu. atinenled.

( b ) 3ONi-IORu, us-caw.

(c ) 2ONi-IORii. as-cast,

P+% x 800

x 300

x 400

x 300

x 400

6+P+q. x 600

( d ) 10Ni-ZORu. AS-CClSt,

(el 20Ni-SRi1, as-cast,

(f) IONi-IORu, annealed,

drite crystals of the 6- and P-phases in the 20Ni- lORu and 20Ni-5Ru alloys, see Figures 3c and 3e, respectively, which lie along both sides of the monovariant curve plU.

The microstructure of the as-cast alloy containing 10Ni-20Ru (Figure 3d) shows the tendency of the 6-phase to overcool. Coarse light grains of the primary &phase can be seen, with small quantities of liquid freezing between them (the dark and very dark areas). A vertical section taken along the iso- concentrate (isopleth) 10 at.% Ni (Figure 4) has been constructed from the known characteristic temperature effects of this alloy (DTA) and from data obtained from the constitution of the boundary Ti-Ni and TiN-TiRu phase diagrams (5,9) and explains the microstructure.

P&mm MetuLr Rev., 2001, 45, (2) 88

Fig. 4 Isopleth through the 10 at.% Ni isoconcen- trate of the Ti-TiNi-TiRu phase diagram, showing processes taking place as the temperature changes, and showing the solidus and liquidus temperatures of the alloys. The isopleth passes through two fields of primary crystallisation of 6- and P-phases and crosses four three-phase regions, connected to the invariant four-phase transformation at 980°C (horizontal line). Two solid-phase regions: P+q and 6+q are seen. The temperature interval of the &phase crystallisation is large compared to the L+p+6 process, the latter is thus inhibited on rapid ingot cooling, resulting in microstructure of as-cast a1lo.y with 10Ni-ZORu, shown in Fig. 3d

L

leoo -

1 6 0 0 - P W

1 0 0 0 .

I I I 15 20 25 30 35 A lONi 5 10

90Ti RUTHENIUM CONTENT, at:/.

6

-

!050

870

The large temperature range of the &phase primary crystallisation and the very narrow one for the following L t) q+p reaction results in non- equilibrium proportions of the phases present (Figures 3d and 4). On subsequent anneahg, the 10Ni-20R1.1 alloy becomes a three-phase alloy

The composition range and field of primary crystallisation of the q-phase (Figure 1) elUpz, is very small.

Monovariant processes L+6 t) q and L t) p+6 proceed to the invariant four-phase equilibri-

(Figure 30.

Fig. 5 Scheme of crystallisation of the Ti- TiNi-TiRu alloys, showing the binary and ternary invariant reactions which contribute to the four-phase peritectic equilibrium L+6 tf P+q. The two three-phase processes: L+6 t) P and L+6 tf 11 occur at higher temperatures than the four-phase process, followed bv L tf P+q after its completion. Phase &q+P precipitates

um reaction L+6 t) p+q which occurs at 980°C in this system (Figure 5.) The composition of the liquid at point 'U' taking part in this reaction is - 24Ni-2Ru, which is close to the liquid composition of the L t) p+q eutectic in the Ti-Ni binary system. Originating on the p+q side of the p+&q tie-line triangle, the L t) p+q monovariant process descends along the Ue, curve towards the Ti-Ni face to the lower temperature of 942°C.

Thus the processes occurring in the Ti-TiN- TiRu system pass from the incongruent reactions observed in the Ti-Ni and Ti-Ru binary systems

Phtinm~ Me& b., 2001,45, (2) 89

(maximum temperature 1575°C) through an invariant reaction in the ternary system (98OOC) down to an invariant eutectic reaction in the Ti-Ni system (342°C).

Assuming that the polymorphic transformation a t;, p can occur in titanium and its alloys, it cannot be expected that the phase equilibria on cooling will be the same as they were at the subsolidus temperature. Decreasing the temperature below 882°C should cause changes to the phase equilibria. Figure 6 shows the Ti-TiNi-TiRu phase diagram, deduced at - 700°C.

The solubility of ruthenium and nickel in a-titanium is known to be small (< 1 at.% (7)). Therefore the mutual solubility of ruthenium and nickel in a-titanium cannot be expected to be greater than this. This fact, together with the broad homogeneous fields of the p- and &phases, and the wide two-phase fields (6+q, q+p, p+6) in the solidus surface of the Ti-TiNi-TiRu subsystem, should result in a h e uniform dispersion of a- phase precipitates as well as intermetallic phases

within these fields. This in turn should lead to changes in the properties of the alloy, especially in the mechanical properties.

Summing Up When using or working with new alloy materi-

als, data is required on the processes that take place in the basic alloys, the nature of the processes, their characteristics and the way in which they influence the mechanical properties of the alloys. In general, information about ruthenium-containing alloys is limited. However, alloys based on the compound TiNi in the Ti-Ni-Ru system, may have medical uses, while ruthenium additions to the shape memory alloy TiNi reduce the restoring capability of the alloy, but contribute to repeated reproduction of the shape memory effect. When ruthenium is added to titanium-based alloys, a substantial improvement in corrosion strength occurs in various environments (2). Advantages of using material with a higher corrosion resistance may override any negative effects.

P/afinwm Met& b., 2001,45, (2) 90

References 1 L. S. Shyriaeva, V. P. Pakhornov, N. G. Boriskina

and V. Kasatkin, in “Alloys of Titanium with Special Physical Properties”, Moscow, Nauka, 1982

2 R. W. Schutz, PLdn#m Met& Rev., 1996,40, (2). 54 3 J. H. Potgier and H. C. Brookes, Com~ Eng., 1998,

51, (4), 321 4 K. R. Seddon, Phtin#m Metals&., 1996,40, (3), 128 5 E. L. Sernenova, N. Yu. Rusetskaya, V. M. Petpkh and V. Ye. Listovnichiy,J. P h Eqdb., 1995,16, (4), 297

6 E. L. Semenova, N. Yu. Rusetskaya and V. M. Petyukh, P h f i n ~ m Met& Rev., 1995,39, (4), 174

7 N. G. Boriskina, I?. M. Nu#k USSR, Sn: Met., 1983, (Z), 222

8 N. G. Boriskina, Inst. Metallurgy of the Akademy of Science of the USSR, Moscow, 1980, Dep. in VINI- TI 19.11.80, N 4907-80

9 T. B. Massalski, “Binary Alloy Phase Diagrams”, ASM, Ohio, 1991

The Authors Elena Semenova is a Senior Research Worker at the I. N. Frantsevich Institute for Problems of Materials Science, in Kiev. Her interests are transition metal systems, phase equilibria and related properties. She currently studies Cu-Sn-(Ga)-Ti(2r) alloys.

Nataliya Krendelsberger was a Junior Research Worker at the I. N. Frantsevich Institute for Problems of Materials Science, studying phase equilibria in Ti-Ni-Ru and Ti-Ni-Sc systems,

Ruthenium-Manganese Artificial Photosynthesis Systems Solar energy is a promising source for sustainable

production of fuel and electricity. One way to har- vest solar energy is to mimic natural photosynthesis using an artificial system. In plant photosynthesis the key enzyme is Photosystem 11, (PSIq, where light is absorbed by a chlorophyll unit, starting the conversion of light energy into chemical energy. PSII contains a triad: a cluster of four manganese (Mn) ions which transfer electrons, via tyrosinez (a redox active amino acid) to the photooxidised chlorophyll P6M+, which uses the electrons to oxidise water molecules to oxygen. A crucial part of this process is electron transfer from the Mn to p6We. Lght drives electron transport fiom water to a quinone acceptor which is reduced and used further in bioreactions.

Researchers from Stockholm University, Uppsala University and the University of Lund, Sweden, are currently designing and synthesising multifunctional supramolecular complexes hoping to achieve the

light-driven oxidation of water, based on the principles of PSII (L. Sun, L. Hammarstrom, B. hermark and S . Styring, Cbem. SOC. Rev., 2001, 30, (l), 3649). They have investigated progressively more complex systems. Synthetic multinuclear ruthenium (Ru)-Mn complexes, in which a Ru tris-bipyridine complex replaces the P680, can mimic the electron transfer. A tyrosine unit replaces the tyrosinez of PSII. An external electron acceptor accepts an electron transferred by the Ru complex upon absorption of light. The photogenerated Ru(TI9 then recovers an electron from the h4n cluster or the tyrosine unit and reverts to RuQl). The Mn cluster has appropriate redox properties and is capable of multiple electron transfer needed for splittjng water molecules. The Mn complexes are oxidised or a tyrosine radical is generated. The model system closely mimics the primary reaction steps on the donor side of PSII, but as yet catalgc water oxidation has not been achieved.

The Seventh Grove Fuel Cell Symposium The seventh Grove Fuel Cell Symposium will U.K. Tel: +44 (0)1865 843691; Fax: +44 (0)1865

take place at the Queen Elizabeth IT Conference 843958; E-mail: [email protected]; Centre, London, on 11-13th September 2001. The Website: www.grovefuelcell.com. Symposium, entitled ‘Commercialising Fuel Cells: The Issues Outstanding’, is intended to give dele- &fa Aesar N-In-One Catalogue gates an up-to-date global review of the technology Alfa Aesar has published its 2001-2002 and applications of fuel cells. The major subject “Inorganics, Organics, Metals and Materials” cata- areas for discussion will include: stationary fuel cells, logue. The ‘Al-In-One’ edition contains Alfa transport applications, portable power, defence Aesar’s entire product range of nearly 25,000 items. applications and significant developments in new A facility on the Alfa website enables platinum lab- science and technology. ware to be selected and specified in terms of

There will be an extensive poster display and an capacity, weight and material. A structure-searchable exhibition area. Further details may be obtained CD-ROM is also available. from Ms Sarah Wilkinson, Seventh Grove Fuel Cell For a free copy of this catalogue, please contact Symposium, Elsevier Science, The Boulevard, Alfa Aesar, Tel: +1 800 343 0660; Fax: +1 978 521 Langford Lane, Kidlington, Oxford O X 5 IGB, 6350; E-mail: [email protected]; Website: www.alfa.com.

Phtinzm Met& &., 2001, 45, (2) 91

ABSTRACTS of current literature on the platinum metals and their alloys

PROPERTIES The Tin-Rich Part of the Au-Pt-Sn System A. N. TORGERSEN, L. OFFERNES, A. KJEKSHUS and A. OLSEN, /. Ahys C o e d , 2001,314, (1-2), 92-95

Condensed phases, tie-lines and tie-mangles for an isothermal section of the Sn-rich part @ 50 at.Yo) of the Au-Pt-Sn phase diagram at 400°C are presented. There is a limited solid-solubility exchange between Au and Pt in most of the binary phases; however, for AuSn and Pt~Sn3 the ranges of homogeneity are appreciable. AuPtzSn, was also found.

Grain-Boundary Segregation of Impurities in Iridium and Effects on Mechanical Properties L. HEATHERLY and E. P. GEORGE, Actu Muter., 2001, 49, (2), 289-298

Impurites of Fe, Ni, Cr, Al and Si (5CL5000 ppm) were added to Ir-0.3 W-0.006 Th-0.005 Al to examine their effects. Fe, Ni, Cr and Al do not segregate to the grain boundaries of Ir, even when present at bulk levels of 3000-5000 ppm. Very low levels of Si (50 ppm) in the bulk segregate to It grain boundaries and at bulk levels of Si (< 200 ppm), both Th and Si segregate to the Ir grain boundaries. Fe, Ni, Cr, Al (and Si at low levels) do not embrittle Ir, whereas high levels of Si cause severe embrittlement.

CHEMICAL COMPOUNDS Peculiarities of KzPdC14 and KzPtC14 Complexation with Polymer-Supported Dibenzo-18-crown-6 G. G. TALANOVA, K B. YATSIMIRSKII and 0. v. KRAVCHENKO, Ind. Eng. Chem. a s . , 2000,39, (lo), 3611-3615

Dibenzo-18-crown-6 supported on a styrene- divinylbenzene copolymer matrix (PDB18C6) is an efficient sorbent of Pt(Il) and Pd(II) from aqueous KzPtCL and KzPdCL solutions, respectively. The sorption proceeds via coordination of K' with the crown ether 0 atoms accompanied by the complex cation association with FtCl$ and ~d,C1z,+2]Z~. PDB18C6 shows stronger binding of Pt than of Pd.

Determination of Absolute Configuration of (n-Allyl)Palladium Complexes by NMR Spectroscopy and Stereoselective Complexation A. GOGOLL, c. JOHANSSON, A. A X ~ N and H. GRENNBERG, Cbem. Egr. J., 2001,7, (Z), 396403

The (SJ- and (R,R)-enantiomers of the chiral chelating &and AT,"-bis(phenylethy1)bispidine form complexes with (n-ally1)Pd species with hlgh stereose- lectivity. In the 'H NMR spectra of the resulting complexes, signals of "antenna" protons were easily identified. Interligand nuclear Overhauser effects involving these protons enabled the absolute stereochemistry of the (n-allyl)Pd complex to be determined.

Characterization of the Inorganic/Organometallic Osmium(lV) Compound [Cp*zOs'vC1lz[Os'vCIsl as Formed by the Reaction of OsCI, with Pentamethylcyclopentadiene in Air T. SNT, w. KA~M and w. PREETZ, Z. Nu~forsch.., 2000,55b, (3/4), 235237

oscl3 was reacted with pentamethylcyclopentadiene in EtOH in air to give the ionic O s o compound [Cp*~OsCl]~[OsC~], which contains two O s m ions. Under similar conditions the RuC13 homologue gave the Ru(III) compound [Cp*zRuCl~]~, confirming the more facile oxidation of mvalent 0 s to the tetravalent state.

Ruthenium Terpyridine Complexes with Mono- and Bi-Dentate Dithiolene Ligands H. SUGIMMO, K TSUGE and K TANAKA, J. Cbem. Soc., D&n Trum., 2001, (l), 57-63

pu(CO)zCl(terpy)]PFs (1) (terpy = 2,2':6,2"-terpyr- dine) reacts with Nazmnt (mnt = SzCz(CN)2) to give initially ~u(CO)~(mnt-~(terpy-~iViV'")] , which then rearranges to ~u(CO)z(mnt-KZSS')(terpy- K2iVi")I in solution. (I) reacts with 3,Ctoluenedithiol (Hztdt) to give [Ru(CO)z(tdt-l?i-SS) (terpy-i?")].

ELECTROCHEMISTRY Analysis of the Activation Mechanism of Hydrogen Storage Alloy Negative Electrodes Containing Palladium Ion-Adsorbed Carbon Powder s. MORISHITA, K. FUJITA, K. ITOH, s. TOWATA and K. ABE, Nippoon Kagah f i sh ( 2000, (ll), 77s778

Pd2+/C powder (1) has been used to promote the initial activation of the HZ storage alloy negative electrodes in Ni-MH batteries. Electrode impedance values, and ' E M and XRD of (1) were taken after cathodic polarisation. A mechanism is proposed Pd" is reduced to fine Pd particles during the first charge. The h e Pd particles act as active sites for charge/dis- charge reactions. The alloy particles are pulverised due to volume expansion on HZ absorption; new active sites are formed on the fresh alloy surface.

Zeolitic Inorganic-Organic Polymer Electrolyte Based on Oligo(ethy1ene glycol) 600 KZPdCl4 and K&O(CN)6 V.DINOTO, J. &'&. Cbem. B, 2000,104, (M), 1011610125

Aqueous solutions of K,PdC& and K,Co(CN), were combined separately with poly(ethy1ene glycol) 600 and then reacted together to give a zeolitic polymer electrolyte, [CoxPd,(CN)~l,(CHz,H,,,,O,+l)Kn (1). (1) conducts ionically by two distinct conductivity regions which follow Arrhenius-type equations. At 25°C (1) has conductivity - 3 x S cm?.

PLationwm Metuh Reu., 2001,45, (2), 92-96 92

PHOTOCONVERSION low-lying Electronic States and Photophysical Properties of Organometallic Pd(ll) and Pt(ll) Compounds. Modern Research Trends Presented in Detailed Case Studies H. YERSIN and D. DONGES, Top. cum. Chem., 2001,214, 81-186

A review of photophysical research is presented, using two homologous organometallic compounds

thieny1)-pyridinate) as representative compounds. The triplets of (1) and (2) are marked by differences of nearly two orders of magnitude in metal/MLCT character. e h l y resolved spectra are obtained in n- octane, at low temperature (1.3 K ) and by laser spectroscopy, allowing detailed analysis. (191 Refs.)

Pd(2-thpy)z (1) and Pt(2-thpy)z (2) (2-thpy- = 2-(2-

New Luminescent and Redox-Active Homometallic Dinuclear Iridium(lll), Ruthenium(l1) and Osmium(ll) Complexes Prepared by Metal-Catalyzed Coupling Reactions P. M. GRIJFITHS. F. LOISEAU, F. PUNTORIERO. S. SERRONIand S. CAMPAGNA, Chem. Commm., 2000, (23), 2297-2298

Complexes [@py)Jr@hen-phen)Ir@py)z]z+ @py 7 monoanion of 2-phenylpyridine; phen-phen = 5,5 - bis(1 ,lo-phenanthroline)), [(bpy)zRu@hen- hen

[~bpy)~Os@hen-phen)Os~e~bpy)*]"'ezbpy = 4,4 -dimethylL2,2'-bipyridine) were prepared. They exhibit relatively intense room temperature lumines- cence which can be attributed to 'MLCT levels.

R Ld RU@PY)Zl4+> [@PY)zOs@hen-Phen)Os@PY)zl

Rapid Synthesis of New Emitting Ir(lll) Polypyridine Complexes N. YOSHIKAWA, Y. MASUDA and T. MATSUMURA-INOUE, ch. Lett.]pn., 2000, (lo), 1206-1207

Microwave-assisted synthesis of Ir(I1I) polypyridine complexes, such as pr(bpy)3](PF&, has been achieved in ethylene glycol in a 500 W microwave oven of frequency 2450 MHz. The OH group of ethylene glycol was activated. These complexes were characterised by intense phosphorescence emission (505630 nm).

On the Photochemical Behavior of the IRu(NH3)4(NO)nicotinamide13' Cation and the Relative Stability of light-Induced Metastable lsonitrosyl Isomers of Ru Complexes c. KIM, I. NOVOZHLOVA, M. s. GOODMAN, K A. BAGIXY and P. COPPENS, Inorg. Cbem., 2000,39, (25), 5791-5795

Low-temperature IR experiments on crystalline samples of trans-~u~H~)~~O)nicotinamidmide]'+ salts (1) show a hght-induced absorption band typical for isonitrosyl MS1 NO linkage isomers upon exposure to 300-500 nm light from a Xe source. The formation of a metastable species was confirmed by DSC measurement on (1) irradiated at low temperature with 457 nm llght from an Ar' laser. The hght- induced species decays at 250-260 K.

APPARATUS AND TECHNIQUE Electrochemical Sensing of Glucose at a Platinum Electrode with a Chitin/Glucose Oxidase Film K SUGAWARA, H. FUKUSHI, S. HOSHI and K AKATSUKA, A n d Sci., 2000,16, (ll), 1139-1143

An electrochemical glucose sensor, which can detect glucose in liquids, uses a Pt electrode covered with a chitin/glucose oxidase film. Glucose oxidase having a negative charge was immobilised on a pro- tonated chitin hlm in 0.1 mol dni3 acetate buffer @H 5.0) via an electrostatic interaction. An oxidation peak of HzOZ from the enzyme reaction occurs at +0.5 V (vs. Ag/AgCl) in 0.1 mol dn-' acetate buffer @H 6.2). The calibration curve of glucose was linear from 5 x 10-'-3 x mol ~II-~.

Reagentless Biosensor for lsocitrate Using One Step Modified Pt-lr Microelectrode A. C. PEREIRA, F. L. FERTONANI, G. DE OLIVEIRA NETO, L. T. KIJBOTA andH. YAMANAKA, Takantu, 2001,53, (4), 801-806

An isocitrate biosensor (1) had the isocitrate-dehy- drogenase-ICDH enzyme, the NADP' coenzyme and Meldola's Blue mediator immobilised on the surface of a Pt-k microelectrode. Catalytic currents were proportional to isocitrate concentrations: 7.7 x 104-1.04 x lo4 mol 1-'. The detection limit of (1) was 3.50 X lod moll-'. The response time < 20 s, the lifetime - 30 determinations and no significant inter- ference was noticed from sugars or cimc acid.

Sensing Properties of Palladium-Gate MOS (Pd-MOS) Hydrogen Sensor-Based on Plasma Grown Silicon Dioxide D. DWIVEDI, R DWNEDI and s. K SRIVASTAVA, SOU. AmMtws B, Chem., 2000,71, (3), 161-168

A Pd-gate MOS Hz sensor (1) was fabricated on a n-type (100) Si wafer having resistivity of 1 4 R cm using plasma technology. The response-recovery time and sensitivity of (1) were studied for Hz concentrations of 1480-11,840 ppm at signal frequencies of 500 Hz, 10 and 100 lrHz at room temperature. Hz- induced interface-trapped density was evaluated as a function of gas concentration using a bias scan con- ductance method. (1) has improved performance: high sensitivity and low response recovery time.

Gas-Sensing Properties of PdO-Modified S n 0 ~ F e ~ 0 ~ Double-layer Thin-Film Sensor Prepared by PECVD Technique M. s. TONG, G. R DAI and D. s. GAO, VUCZMZ, 2000,59, (4), 877-884

SnOz-Fez03 double-layer thin films were fabricated onto Si and ceramic substrates by using the plasma- enhanced CVD technique. The SnOz surface was then coated with PdO and CO sensing properties were tested. Pd was deposited onto the films by dip- ping them into a solution of PdCl2, followed by reducing the Pd" with formaldehyde and SnClZ. The hlms have hlgh sensitivity and selectivity to CO.

P/arn#m Metuh Rev., 2001, 45, (2) 93

The Removal of Ammonia from Water by a Hydrophobic Catalyst T:L. HUANG, K. R. CLIFFE and J. M. MacINNES, Envimn. sci. Techno/., 2000,34, (22), 48044809

A process for removing NH3 from HzO involves stripping NH3 from the aqueous phase followed by gas-phase oxidation of NH3 over a Pt/styrene divinyl benzene copolymer hydrophobic catalyst (1) at 9S125"C. The stripping and catalytic oxidation were carried out simultaneously in a continuous trickle-bed reactor, where the packing material was a mixture of (1) and Y-AlzO, spheres. The NH3 concentration in the inlet gas was 50Ck1500 ppmv.

Formation of Platinum Silicide on a Platinum Nanoparticle Array Model Catalyst Deposited on Silica during Chemical Reaction J. ZHU and G. A. SOMORJAI, Nuno Lett., 2001,1, (I), 8-1 3

Pt nanoparticle model catalysts with 28 k 2 nm diameters and 100 f 2 nm square periodicity have been fabricated with electron beam lithography on SiOz substrates. The reactivity and selectivity of the Pt/SiOz array favour dehydrogenation for a cyclo- hexene and Hz mixture, not hydrogenation, at 100°C. Experiments with Si deposited on Pt foil show that Pt silicide could form at the Pt/SiOz interface.

The Mechanism of Palladium-Catalyzed Decomposition of Ethanol - A Comparison of Chemical Kinetic and Surface Science Studies J. M. DAVIDSON, c. M. MCGREGOR and L. K DORAISWAMY, Ind Eng. Chem. Res., 2001,40, (l), 108-113

The decompositions of EtOH and acetaldehyde over Pd/Al203 were studied in pulse reaction mode at 200°C in flowing He and with added Hz, CO and HzO. Acetaldehyde decomposes to CH, and CO with progressive coking that can be suppressed by Hz. The response times, as monitored by MS peaks for CH4 and CO, were very similar. EtOH decomposed to CHs/CO/HZ, the corresponding traces being either broad and unsymmetrical or resolved into two peaks. In HJHe, the slower set of responses is suppressed, and those from CH4 and CO appear sharp and sim- lar in shape to those observed from acetaldehyde.

Environmentally Benign Oxidation Using a Palladium Catalyst System M. HAYASHI, K. YAMADA, s. NAKAYAMA, H. HAYASHI and S. YAMAZAKI, Green Chem., 2000, 2, (6), 257-260

Benzylic and allylic alcohols were converted into the corresponding carbonyl compounds in the presence of 2&50 wt.% of 10% Pd/C, with 3 equiv. of vinyl acetate or under a CzH4 atmosphere in MeCN, at 5Ck80"C. The product distribution of the reaction of 2-cyclohexen-1-01 with 5 moWo of Pd(0Ac)z under a CZK atmosphere was 68% phenol, 28% cyclohexanone and 4% cyclohexanol. In the oxidation of D-glucal to 1,5-anhydrohex-l-en-3-ulose using Pd(OAc):! and vinyl acetate, the Pd catalyst can be reused without a decrease of catalytic activity.

Heterogeneous Catalysis on the Atomic Scale G. ERTL, Chem Rec., 2001,1, (I), 33-45

The progress of catalytic reactions on an atomic scale was observed using NH3 oxidation and other reactions as examples and by utilising scanning tun- nelling microscopy and other surface techniques. CO oxidation on a Pt(ll1) surface proceeds preferential- ly along the boundaries between adsorbed 0 and CO patches. Ru is practically inactive for the same reaction under lower pressures but is transformed into RuOz at atmospheric pressure, where some of the surface Ru atoms function as coordinatively unsaturated sites. In the Hz oxidation reaction on Pt(lll), an autocatalytic reaction step occurs.

Investigation of the Operation Time Dependence of the Yield of Ammonia Conversion to Nitrogen(l1) Oxide by Platinum Catalyst Sets P. A. KOZUB, N. v. TRUSOV, G. I. GRYN and v. v. PREZHDO, J. Chm. Technol. Biotechnol., 2001,76, (2), 147-152

The origins of changes in the catalytic activity of Pt catalysts used for the NH3 oxidation reaction were studied. A general mathematical model for the dependence of the catalyst activity upon the operation time of a single Pt gauze is proposed. The model can be used to determine the gauze operating times, to calculate the average product yields for various types of operating conditions, and to select the opti- mal gauze rotation procedure.

Heterogeneous Enantioselective Hydrogenation of Ethyl Pyruvate Catalyzed by Cinchona-Modified Pt Catalysts: Effect of Modifier Structure H. u. B L A ~ E ~ H. P. J A L E ~ , w. L O ~ B A C H and M. STUDER, J. Am. Chem. Soc., 2000,122, (51), 1267S12682

The effect of the structure of chiral modifiers derived from natural cinchona alkaloids on the enan- tioselectivity and rate of the Pt/AlzO3-catalysed hydrogenation of ethyl pyruvate is reported. The strongest effects on ee, but somewhat less on rate, were observed for changes in the O - C p C r N part of the cinchona alkaloid and for partial or total hydrogenation of the quinoline rings.

Pt/Ce02 Catalysts in Selective Hydrogenation of Crotonaldehyde: High Performance of Chlorine- Free Catalysts M. ABID and R. TOUROUDE, Catal. Lett, 2000, 69, (3, 4), 139-144

The hydrogenation of crotonaldehyde was con- ducted in the gaseous phase at atmospheric pressure, on Pt/CeOz catalysts (1) prepared from metal pre- cursors, some containing C1. (l), prepared from Pt(NH3)4(N03)z, led to 5 2 0 % crotyl alcohol selectivity when (1) was reduced at 4 7 M 7 3 K. When the reduction temperature was increased up to 973 K, the crotyl alcohol selectivity reached > 80%. When (1) contained C1, crotyl alcohol selectivity was < 30%.

Phinum Metoh Rev., 2001,45, (2) 94

H ETE R 0 G EN E 0 US CATALYSIS

H 0 M 0 G EN EO U S CATALYSIS Ionic Liquids in Regioselective Platinum- Catalysed Hydroformylation P. WASSERSCHEID and H. WAFFENSCHMIDT, J. MoL C& A: Cbem., 2000,164, (1-2), 6147

Room temperature liquid chlorostannate ionic liquids (1) have been used as solvents for the catalyst (PPh3),PtC12 (2). (1) were prepared by the reaction of 1 -butyl-3-methylimidaolium chloride or 1 -butyl-4- methylpyridinium chloride with SnCIZ. (2) dissolved in (1) has enhanced stability and selectivity in the hydroformylation of methyl-3-pentenoate compared to the identical reaction in conventional organic solvents. In the case of 1-octene hydroformylation, a biphasic reaction occurs when using (1) as the catalyst solvent for (2).

Salt-Free C-C Coupling Reactions of Arenes: Palladium-Catalyzed Telomerization of Phenols A. KROTZ, F. VOLLMiiLLER, G. STARK and M. BELLER, Chem. Commnn., 2001, (2), 195-196

Electron-rich phenols were reacted with 2 molecules of 1,3-dienes (butadiene, isoprene) in the presence of Pd(OAc)z-PR, catalysts (R = Cy, Ph, (OC6H3(C.,H&)) to give C-allylated phenols. After reduction with H2 and Pd/C the corresponding alky- lated products were obtained in high yields. This telomerisation of phenols with dienes constitutes a salt-free functionalisation of the aromatic nucleus and has remarkable catalyst turnover numbers.

A New Efficient Palladium Catalyst for Heck Reactions of Deactivated Aryl Chlorides A. EHRENTRAUT, A. ZAPF and M. BELLER, $ n h ~ , 2000, (1 1). 1589-1592

A new Pd catalyst consisting of Pd(dba)z and di-l- adamantyl-n-butylphosphine (1) has been developed for the Heck reaction of non-activated and deactivated aryl chlorides. (1) gives improved results for the Heck reactions of non-activated q l chlorides than previously known catalyst systems.

Rhodium Catalyzed Hydroformylation of 1,l -Bis(p-fluorophenyl)allyl or Propargyl Alcohol: A Key Step in the Synthesis of Fluspifilen and Penfluridol c. BOTTEGHI, M. MARCHETIT, s. PAGANELLI and F. PERSI-PAOLI, Tetrubedmn, 2001,57, (8), 1631-1637

A key intermediate, 4,4-bis@fluorophenyl)butyl- bromide, in the synthesis of the neuroleptic agents, Fluspirilen and Penfiridd, has been prepared starting from commercially available 4,4’-difluorobenzophe- none (1). The preparation of (1) involved the Rh catalysed hydroformylation, in toluene or in the biphasic system toluene/HzO or cydohexane/HzO, of 1,1-bis(pfluorophenyl)-2-propenol(2) and/or 1,l- bis@fluorophenyl)-2-propynol. For (2), the HzO soluble catalytic systems [Rh(COD)Cl]Jl”PTS and Rh(CO)2acac/2,7-bis(SO~Na)zXantphos were used.

Selectivity of the OSHCI(CO)(O~)(PC~~)~ Catalyzed Hydrogenation of Nitrile-Butadiene Rubber J. s. PARENT, N. T. M~MANUS and G. L. REMPEL, J. &L P05m. Sci, 2001,79, (9), 161S1626

OSHC~(CO)(O~)(PC~~)~ (1) is an efficient catalyst precursor for the hydrogenation of olefin within acry- lonitrile-butadiene copolymers. The nitrile unsaw- ation of the copolymer remains intact. However, (1) catalyses an undesirable crosslinktng reaction, which is not produced by the commercial Rh-based systems. Further research of (1) may overcome this.

The Development of LzXZRu=CHR Olefin Metathesis Catalysts: An Organornetallic Success Story T. M. TRNKA and R H. GRUBBS,ACC. Cbem. Res., 2001,34, (l), 18-29 ‘ The evolution of Ru-based olefin metathesis catalysts from simple salts to highly tuned alkylidene complexes is described. Particular emphasis on (PCy3)zC12Ru=CHPh and its derivatives is given. Trends in catalyst activity are analysed and catalysts coordinated with N-heterocyclic carbene ligands are described. Ongoing work to improve the activity, stability and selectivity of this family of LXzRu=CHR complexes is overviewed. (85 Refs.)

FUEL CELLS Fuel Cells: Principles, Types, Fuels, and Applications L. CARRETTE, K. A. FRIEDRICH and u. STIMMING, ChemPlyChem, 2000,1, (4), 162-193

In this review, the main reactions responsible for the conversion of chemical into electrical energy in fuel cells are given and the thermodynamic and kinetic fundamentals are stated. The theoretical and real efficiencies of fuel cells are also compared to those of the I.C.E. The different types of fuel cells and their main components are explained and related material issues are discussed. A section is devoted to fuel generation and storage. Attention is also given to the integration of fuel cells into complete systems. (191 Refs.)

Electroxidation of HP on PVC Pt-Ru/C and Pt-Mo/C Anodes for Polymer Electrolyte Fuel Cell A. POZIO, L. GIORGI, E. ANTOLINI and E. PASSALACQUA, Eiectmcbim. Ada, 2000,46, (4), 555-561

A semi-empirical equation that fits experimental electrode potential vs. current density data for gas diffusion anodes using Pt/C, Pt-Ru/C and Pt-Mo/C electrocatalysts is reported. A physico-chemical inter- pretation of all parameters used in the equation is given. The presence of a strong kinetic limitation on Pt-M/C (M = Ru, Mo) electrodes was demonstrated. A Heyrovsky-Volmer mechanism for the HZ oxidation reaction is proposed on Pt-M/C (M = Ru, Mo). Some Pt-Mo anodes showed performances comparable to the Pt-Ru (1:l) anode.

95 Phinum Metoh Rev., 2001,45, (2)

Effect of Structure of Carbon-Supported PtRu Electrocatalysts on the Electrochemical Oxidation of Methanol Y. TAKASU,T. FUJIWARA, Y. MURAKAMI, K. SASAKI, M. OGURI, T. A s m and w. SUGIMOTO, J. Ekchchem. Soc., 2000,147, (12), 44214427

Pt-Ru/C electrocatalysts (1) were prepared from EtOH solutions of Pt(NH3)z(NO~)~, Ru~(CO),Z, Rfio(N03), and RuCl,, and C black. The Cl-free Ru~(CO)IZ and RuNo(No3), gave highly dispersed and uniform PtRu nanopartides. Ru3(CO)Iz yielded hgh surface area catalysts. (1) from EtOH solutions of P~(NH~)~(NO~)Z-RU~(CO)~~ had high mass-specific activity toward MeOH oxidation.

Electrocatalysis in Direct Methanol Fuel Cells: In-Situ Probing of PtRu Anode Catalyst Surfaces H. N. DINH, x. REN, F. H. GARZON, P. ZELENAY and S. GOTTESFELD, J. Elechoanal. Chem., 2000, 491, (l-z), 222-233

Sttipping voltammetry of CO adsorbed at unsupported, hghly dispersed PtRu anode DMFC catalysts was used as an in sihr probe of surface composition. CO stripping data for three dispersed, unsupported PtRu catalyst samples indicates that surface metal alloy domains of atomic ratio Ru:Pt near 1:l are the key for higher DMFC anode activity. Catalyst free of blocking by oxide components gives highest activity.

ELECTRICAL AND ELECTRONIC ENGINEERING Growth-Induced Perpendicular Magnetic Anisotropy and Clustering in Ni,Ptc-, Alloys D. VASUMATHI, A . L. SHAPIRO, B. B. MARANVILLE and F.HELLMAN,]. Map. Map. Muter., 2001,223, (3), 221-232

Polyciystalline and epitaxial (loo), (110) and (111)- oriented Ni3Pt, NiPt and NiPt3 films were vapour deposited at 8&7OO0C. At moderate growth temperatures ( 2 O W O " C ) , the films exhibit growth-induced properties similar to those of Co-Pt alloys: enhanced and broadened Curie temperature, perpendicular magnetic anisotropy and large coercivity. Unlike Co-Pt, NiPt hlms exhibit a strong orientational dependence of anisotropy and enhanced Curie temperame.

Low Temperature Synthesis of Silver-Palladium Alloy Powders Internal Electrodes for Multilayer Ceramic Devices R. UEYAMA, K. KAMADA, M. HARADA, T. UEYAMA. T. YAMAMOTO, K. KURIBAYASHI, K. KOUMOTO and T. SHIOSAKI, J. Mater. Sk., 2001,36, (Z), 371-379

Ag-Pd pastes were prepared from: (a) coprecipitated powder, @) agglomerated alloy powder made by heat treatment, and (c) pulverised alloy powder produced by an improved pulverisation method. Paste from (c) showed a hgher film packmg density (6.3 g ~ m - ~ ) than those from (a) and (b). The film consisting of (c) had a lower expansion at - 500"C, a lower shrinkage at 700-1 100°C and a lower elecmc resistivity.

Correlation between Magnetic and Transport Properties of Co/lr/Co Sandwiches and Surface Roughness s. COLIS, G. SCHMERBER and A. DINIA, Thin S o M F i h , 2O00, 380, (l-z), 137-141

Co~,/Ir,/Co3, sandwiches with 0.5, 1 and 1.5 nm thickness of Ir were deposited on glass substrates covered by a F e 5 m / C ~ ~ . ~ m / C ~ ~ n m layer, using the ion beam sputtering technique. The maximum giant magnetoresistance and coupling strength were 2% and -0.55 erg cm?, respectively. The average surface roughness was - 0.3 nm, allowing antiferromagnetic exchange coupling to be seen in the sandwich stack.

Anisotropic Etching of Ru02 and Ru with High Aspect Ratio for Gigabit Dynamic Random Access Memory

(4), 19 11-19 14 T. YUNOGAMI and K NOJIRI, J. Vuc. Jk. TechnoL B, 2000,18,

Anisotropic RuOz and Ru etching technology for gigabit DRAM has been developed using high density O2 + 10% C12 plasma in an inductively coupled plasma etching system. The taper angle for RuOz/Ru increased with decreasing pressure, with increasing 0 2

+ 10% Cl, flow rate and with increasing overetch t h e . Under conditions of low pressure, high gas flow rate and 100% overetch time, a 0.3 pm thick Ru02/Ru pattern having 0.2 p critical dimension and a taper angle of 89" was obtained.

MEDICAL USES Carboplatin Decomposition in Aqueous Solution with Chloride Ions Monitored by X-Ray Absorption Spectroscopy E. cum, K. PROVOST, I. NICOLIS, D. BOUVET, s. BENAZETH, s. CRAUSTE-MANCIET, F. BRION and D. BROSSARD, New J. Chem, 2000,24, (12), 100S1008

X-Ray absorption spectroscopy has been used to study carboplatin (1) in HzO, with C1- at different concentrations. (1) is the major compound present in solution, even after 15 days, in neutral solutions with C1- concentrations < 9%, exposed to hght or not. With high C1- concentrations (18%) or in acidic solutions (0.1 M HCl), (1) is chlorolysed and cisplatin formation as the decomposition product is observed.

Ruthenium( II) Complexes Containing Bidentate Schiff Bases and Their Antifungal Activity N. DHARMARAJ, P. VISWANATHAMURTHI and K NATARAJAN, TrunrifionMet. Chem., 2001,26, (1-Z), 105-109

pluHCl(CO)(PPh&(B)] complexes (B = PPh3, pyri- dine by) or piperidine (pip)) were reacted with bidentate Schiffbase hgands (from condensations of saliqdaldehyde with aniline, 0-, m- orptoluidine) to give puCl(CO)(L- (PPh3)(B)] (1) (L = Schiff base anion). In Vitm activity against fungus Aspergillusflavus was: [RuCl(CO)(sal-p toluidine)(€'Ph3)@y)] puCl(CO)(sal-ptoluide)-

(~al-aniline)(€'Ph~)~] > sal-ptoluidine > sal-aniline. (P%)Z] > l J b q C O ) ( s ~ - ~ ) ( P P h 3 ) @ ~ ) ] > W W 0 ) -

Phbmm Metuh h., 2001,45, (2) 96

NEW PATENTS ELECTROCHEMISTRY Electrolytic Purification of N03--Containing Water IONEX LTD. Bitisb AppL 2,348,209

The electrolytic removal of NO3- ions (1) from HzO involves electrolysing with current passed between a Rh coated cathode and an anode. HzO can also be passed through an ion exchange column containing nitrate-selective anion resin to exchange with HCOs- (2) and/or Cl- ions. In the eluted solution, (1) are converted by electrolysis to N2 gas and the solution is replenished with (2) and/or Cl-.

Cermet Composite for Inert Electrodes ALCOA INC. US. Patent 6,126,799

A cermet composite (1) for inert electrodes is prepared by treating a mixture comprising a compound of Fe and a compound of Ni, Sn, Zn, Y, Cr and/or Ta; and an d o y or mixture containing 7C99.8 wt.% Cu and 0.2-30 wt.% Pt, Pd, Rh, It, Ag or Au at elevated temperature in an atmosphere containing 0 2 .

(1) is used as anodes in molten salt baths for production of metals by electrolptic reduction.

ELECTRODEPOSITION AND SURFACE COATINGS Platinum Electroforming or Electroplating Bath HONG KONG PRODUCT. comic. Brit& AppL 2,351,089

A Pt electroforming or electroplating bath comprises: 15100 g 1-’ Pt (Ptm and P t o ) as haloplatinics or haloplatinics of alkali metals; and 50-400 g 1-’ of an acid of sufficient strength to maintain pH I 1 in the bath. The bath is used to produce hollow Pt jewdlety and for medical, electronic and aviation uses.

Anodes Used in Steel Strip Electrogalvanising U.S. FILTER COW. WorldAppL 00/60,141

An anode (1) comprises a valve metal substrate coated with three subsequent layers containing a Pt group metal or its oxide. (1) has an improved service life at low pH and/or hgh temperature and/or high current density. (1) is used in electrolyte processes for the preparation of Ch, Brz and Hz02; the electrodeposition of Cr, Cu and Zn; and for high speed electroplating such as electrogalvanising of steel strip.

Rhodium Electroplating LUCENT TECHNOLOGIES INC. WodAppL 00/68,149

Rh is reacted with HzS04 to produce a htst Rh sulfate solution which is cooled to < 20°C. This solution is neutralised by addmg a base to precipitate Rh hydroxide while the Rh solution is at < 25°C. Rh hydroxide is further combined with HSO, to produce a second Rh sulfate solution. The electrolyte has pH < 1, the Rh concentration is 1-10 g 1-’ and the Rh sulfate complex does not contain any R h R h bonds. Electroplated layers have low stress and full bright- ness over a thickness of 0.140 microinches.

APPARATUS AND TECHNIQUE pH Electrode U”. SOUTH AUSTRALIA WorldAppL 00/67,010

A pH electrode (1) with a pH-sensitive region on an electrically conductive support comprises a resistive polymer substrate and particles of a Group VA or Group VIII metal, with resistivity of 10-100 ‘Kohms/square’. (1) may be used to measure O2 concentration and to determine the pH of extracellular fluid, intramyocardial pH, etc. (1) is mechanically robust and simple, and accurate at constant O2 pressure.

Nitrogen Oxide Sensor KOREA ADV. INST. SCI. & TECHNOL. U.S. Patent 6,113,859

A bar-type NOx gas sensor for measuring the density of NOx exhaust gas from vehicles comprises a heater formed on an A l 2 0 , bar. A sheet of 1 mm thickness, made of AlzO,, mullite, etc., covers the heater and a Pt thin film electrode is formed on the sheet. A thin WO, sensing film (1) is formed on the electrode. The sensor is used to detect the density of NOx gas accurately, based on variations in electrical conductivity. The sensor has improved structure and prevents temperature variations in (1).

Detecting label-Bearing Targets UNN. NORTH CAROLINA US’. Patent 6,127,127

The presence of label-bearing targets, such as biomolecules in samples, is detected using an electrode containing a non-conducting self-assembled mono- layer of phosphonate molecules having a group covalently bound to a bindmg member. The mono- layer and the target complex are contacted with, for example, Ru(bpy)? to oxidise the label-bearing target. Label-bearing targets such as nucleic acids, proteins, antigens, antibodies, etc., can be detected.

Fabrication of a UV lamp for Cleaning Air CHUNG SHAN INST. SCI. & TECHNOL u.3. pat& 6,135,838

Fabrication of a UV lamp for treating waste gases involves formulation of a photocatalyst coating sol; dip coating a glass fibre cloth with the photocatalyst sol. The cloth, impregnated with oxidation catalyst of Pd, Pt, Au or Ag, is wrapped on a UV lamp. The waste gases are treated by U V irradiation to generate free electron and electron hole pairs which can decompose pollutants into harmless gases.

Cermet Electrodes for Sensors ROBERT BOSCH G.rn.b.H. Gennan A#h. 1/99/06,306307

Cermet electrodes for a sensor are produced by applying a Pt-Zr dioxide paste to a substrate to form electrodes. Zr is added to the paste. The electrodes are sintered and then treated to form 3-phase boundaries, using glass coal as a pore former, to produce open porosity. The sensor determines the O2 concentration in I.C.E. exhaust gases. The current load capacity is increased.

Phfimm Metah Rev., 2001, 45, (2), 97-100 97

HETEROGENEOUS CATALYSIS Hydrogen Refinement Apparatus MATSUSHITA EIBCTRIC IND. CO. LTD.

Eumpean Appl. 1,046,612 A HZ refinement apparatus comprises a reaction

chamber equipped with a CO-shifting catalyst body (1) which contains Pt supported on a metal oxide cai- rier of BET specific surface area of 2 10 mz g-'. Operation of the apparatus is controlled by keeping the temperature of (1) at 15W50"C. The apparatus operates stably when activated and stopped repeated- ly. It provides improved heat resistance and reduced deterioration of (1) and decreases CO concentration.

Production of Pyrroles BASF A.G. Eumpean AppI. 1,046,639

+ole derivatives are prepared by the catalytic dehydrogenation of pyrrolidines at 15&300"C and 0.01-50 bar on a catalyst comprising Pd on a rare earth or Group IVB metal oxide; or Pt and Pd on A1203 or a rare earth or Group IVB metal oxide; and alkali(ne earth) metal oxide. The catalyst has high activity and stability.

Exhaust Gas Emissions Control JOHNSON MAmHEY PLC Wodd&pL 00/53,903

A catalyst system for the aftertxeatment of exhaust gases from a gasoline-fuelled I.C.E. (1) designed to operate under stoichiometric conditions, comprises a first catalyst of Pt and/or Rh, to catalyse a shift reaction between CO and HzO or the conversion of a reactant to generate a Hz-enriched exhaust gas; a source of gaseous 0 2 ; a trap for hydrocarbons; and a three-way catalyst to oxidise catalytically hydrocarbons and CO and to reduce NOx. Pollutants are reduced from (l), particularly during start-up, under rich conditions.

Hemi-Hydrogenation of Dinitriles RHODIA FIBER & RESIN INTERM. WobrM&pl. 00/59,870

Hemi-hydrogenation of dinides into the corresponding aminonitriles uses H2 in the presence of a catalyst system comprising Ru supported on an acety- lene black (1) (obtained by pyrolysis of paraffinic oils). Selectivities of 2 80 % in aminonides for a percent- age transformation of dinitrile of 2 60% may be obtained. (1) gives hgher selectivities in aminonides than obtained with Raney Ni catalysts.

Hydrocarbon Hydrogenation Catalyst PHILLIPS PETROLEUM CO. Work Appl. 00/64,846

A hydrocarbon hydrogenation catalyst, useful for converting highly unsaturated hydrocarbons containing S impurities to less saturated hydrocarbons, comprises Pd/TiOz (l), prepared by combining TiOz and Pd, and drying and calcining the combination. (1) is used for preparing monoolefins from hydrocai- bons with a higher degree of unsaturation, for example, the feed stream from a depropaniser. In the presence of S, (1) provides increased selectivity to a less unsaturated hydrocarbon.

Dual Functional Catalyst for Acid Catalysis CHINA PETRO-CHEM. COW. U.S. Patent 6,117,812

A 0.01-1 or 0.02-0.6% Pd/AlzO, (1) or superacid- type catalyst, for acid catalysis, comprises multiple window lamce shaped pellets each having external teeth with notch peripheral surface area to increase the efficiency of fractionation. (1) is produced by moulding, for example Al(OH),, to a required shape, calcining at 800-1500 or 900-1300"C, ad+ Pd salt solution and drying. (1) can be loaded directly into catalytic distilla- tion columns. Removing the deactivated catalyst is easy.

Selective Dehydrocyclisation of Paraffins UOP I L C US. Patent 6,132,595

A catalyst system for the selective dehydrocydisa- tion of paraffins has a non-acidic large core molecular sieve and a surface layer of one or more of Group IVA metals, In, Group VIE3 metals, Fe, Zn, Au, Bi and uniformly distributed Pt group metal. A bound L-zeolite catalyst with a surface layer of Sn or In and uniformly distributed Pt results in substantial yield improvements in the catalytic reformation process.

Oxidation of Volatile Organic Compounds NASA U.S. NAT. AERO. &SPACE ADMIN.

U.S. Patent 6,132,694 Oxidation of volade organic compounds (VOCs)

to COZ and H20 is initiated at low temperatures. A gaseous mixture comprising a VOC and an oxidising agent (such as ambient air containing the VOC) is exposed to a catalyst (1) containing 1-50 wt.% Pt, Pd, Rh, Au and/or Ag, and 5C99 wt.% of a metal oxide, such as Sn, which possesses one or more stable oxidation states. (1) requires minimum heat and all the oxidised components are non-toxic so air pollution is prevented.

Dehydrocyclisation of Hydrocarbons PHILLIPS PETROLEUM CO. US. Patent 6,140,546

Dehydrocyclisation of hydrocarbons, such as paiaf- fins, is performed by contacting dehydrocyclisable hydrocarbon in the presence of a catalyst containing Pt group metal. ACl3 (0.01-10 ppb) is provided to the dehydrocyclising feed stream. The catalyst has an extended run life and longer operating runs between regeneration. An increased and stable research octane number (RON) and stabllised BTX (benzene, toluene and xylene) production are obtained.

Isomerisation of Xylenes UOP LLC U.S. Patent 6,143,941

A selective process for isomerising a non-equilibri- urn feed mixture of xylenes and ethylbenzene is described. It comprises contacting the feed mixture in the presence of HZ with an oil-dropped spherical catalyst containing a zeolitic duminosilicate (I), a Pt group metal and an amorphous Al phosphate binder. Isomerisation occurs at 3OMOO"C and 100 kPa-5 m a . (1) has a pore diameter of 5-8 A and a 4.6 torr HzO capacity of 3-5 wt.%. The catalyst has superior activity, selectivity and stability.

Pkzhnwn Metuh Rm., 2001,45, (2) 98

Exhaust Purification for Motorcycles YAMAHA MOTOR CO. LTD. JqtJanese AppL 2000/234,514

An exhaust gas purification catalyst for motorcycles has Pt, Rh and Pd as the catalyst elements carried on both surfaces of a plate bent to form a honeycomb, which is then arranged in the enlarged-diameter portion of an exhaust tube (1 ) . Pressure loss in (1 ) is reduced and leads to improvements in engine performance and fuel consumption. Loss by melting, damage or rupture of the catalyst-carrying plate, caused by high temperature, is prevented and the efficiency of hydrocarbon purification during low speed running of the engine is improved.

Combustion of Methane Fuel DENRYOKU CHUO KENKYUSHO

Japanese AppL 2000/254,505 A catalyst for combustion of CH, fuel comprises

using Pd acetate to form Pd or PdO layers on a support containing Sn02. The oxidising property of the catalyst is improved irrespective of temperature. CH, conversion ratio is also improved. The generation of N20 by pre-burning is reduced. The catalyst does not deteriorate even after a prolonged period in use.

Direct Synthesis of Hydrogen Peroxide DEGUSSA-HUELS A.G. Geman AppL 1/99/12,733

A heterogeneous catalyst used in the direct synthesis of HzO2 from HZ and 0 2 , is based on Pd or 1 two metals of the Pt group metals and sub-Group I, optionally using a solvent. The catalyst is produced by spray or flame pyrolysis of an aerosol of a solution or suspension of a metal compound, followed by sep- aration of the resultant metal or alloy particles from the gas stream. The catalyst gives significantly higher HZ selectivity and/or attainable H2Oz concentrations than existing catalysts.

H 0 M 0 GENE 0 US CATALYSIS (2-(Arylsulfonyl)-etheny1)-benzene Derivatives SUMITOMO CHEM. CO. LTD. Brifirsh &pl 2,348,201

A safer and more efficient process ( 1 ) for produc- ing (2- (arylsulfonyl) -ethenyl) -benzene derivatives, useful as intermediates for pharmaceutical and agr- cultural products, is described. ( 1 ) comprises reacting a 2-(arylsulfonyl)-ethanol with an acid anhydride in the presence of a base and reacting the product with an aromatic halide in the presence of a Pd catalyst, such as Pd chloride, acetate, oxide, etc., and a base. (1 ) avoids the handling of solid aryl vinyl sulfones.

Promoted Hydrosilation Reactions CK WTCO COW. Euqbean AppL 1,035,126

Compounds containing Si-C bonds are prepared in high purity by the hydrosilation of hydridosilane with an o le f ic reactant, in the presence of a Pt catalyst and a carboxylic acid promoter having 14C atoms, a molecular weight > 60 and a boiling point > 118°C at atmospheric pressure. The yields and rates of hydrosilation are improved under mild conditions.

GLactone Production FORSCHUNGSZENTRUM KARLSRUHE G.m.b.H.

European AppL 1,036,79 1 Production of &lactone comprises reacting butadi-

ene and COZ under pressure and at constant reactant mole ratio in the presence of Pd,(dba)j, Pd(PPh+ or Pd(OAc)z/PPh3 (dba = dibenzylideneacetone) catalyst. High yields are obtained at lower operating temperamre. The method is based on the observation that high partial pressures of CO2 inactivate the catalyst and this effect far outweighs the expected advantage of the increased COZ pressure.

Production of Diol Mononitrate Esters DINAMITE DlPHARMA S.p.A. European &pL 1,038,862

Mononitrate esters of dihydroxyakyl, dihydroxy- cycloalkyl or dihydroxypolycycloalkyl compounds are produced by hydrogenating the correspondmg din- trate esters using a Pt(0) catalyst. The process avoids u s i n g carcinogenic hydrazine hydrate and avoids waste disposal problems associated with Zn/acid reduction. Esters, such as isosorbide mononitrate, are useful for treating cardiovascular diseases.

Carbonylation of Conjugated Dienes SHELL INT. RES. MIJ. B.V. WorMAppL00/56,695

A catalyst ( 1 ) for carbonylation of conjugated dienes, such as for the production of dimethyl adi- pate and methyl pentenoate, comprises Pd cations and a bridged cyclic P-containing ligand and anions. The ligand comprises two 5- or more-membered cyclic groups each containing P, linked by a 1 - 4 atom organic group. ( 1 ) has an unexpectedly high activity (allowing molar ratios of conjugated diene to Pd of > 300:l) while st i l l achieving high selectivity.

Optically Active p-Hydroxyester Derivatives UBE IND. LTD. U.S. Patent 6,121,475

An optically active P-hydroxyester derivative (1) is prepared by an enantiomeric aldol addition reaction of an aldehyde and ketene silylacetal in the presence of an organic base and a Pt-containing catalyst prepared from a bisphosphine-aryloxyacyl Pt complex and strong acid in an 02-containing gas. (1) are intermediates for pharmaceuticals and agrochemicals.

FUEL CELLS Solid Electrolyte Fuel Cell SHINKO ELEcTRlC IND. CO. LTD. European &pL 1,058,329

A solid electrolyte fuel cell for generating power includes a solid electrolyte device with electrodes formed on both sides of an ion-conductive solid electrolyte substrate. 0 2 is supplied to the cathode side while CH4 gas is supplied to the anode side. The electrode on the anode side acts as oxidation catalyst for the CH4 fuel. Either CoNi02 or COO particles are blended in a porous Pt layer, or PdCoO2 particles are formed on the surface of the porous Pt layer, as the oxidation catalyst. The fuel cell has superior and more efficient power generation performance.

Plafnum MetaLr Rev., 2001,45, (2) 99

Water Gas Shift Reaction MATSUSHITA ELECTRIC WORKS LTD.

WorMAppL 00/54,879 A catalyst (1) for the HzO gas shift reaction com-

prises at least Pt supported on a metal oxide carrier. (1) has good efficiency in removing the CO in Hz, such as the reformed gas in the electric power- generating system of a fuel cell at 2O&40O0C. (1) is adaptable for use in a start-stop repeat-operation small portable fuel cell power-generating system.

Ternary Catalyst for Fuel Cell Electrode SYMYX TECHNOLOGIES INC. WorMAppl. 00/55,928

A Pt-Ru-Ni catalyst for electrochemical reactor devices, fuel cell electrodes and other catalytic structures, is dispersed on the surface of an electrically conductive support. The electrochemical conversion of a hydrocarbon-based fuel and 0 2 to H20, CO, and electricity in the fuel cell involves oxidising the fuel by contacting with the catalyst. The latter has high catalytic activity and high resistance to poisoning by CO. The efficiency of the fuel cell is improved and its size can be decreased.

Self-support Fuel Battery System TOY0 ENG. CORP. Japanese Appl. 2000/233,903

A self-support type fuel battery system for motor vehicles comprises a methanolysis device (1) and a shift reaction device (2). H2O vapour is supplied to the Hz permeation sides of the Pd films of (1) then (2). A non-transparent gas is formed comprising damp HZ and COZ. Moist HZ is supplied to a fuel cell anode and air to the cathode. Unreacted air, H2 and non-transparent gas are then supplied to the heating unit of (1). Waste gas from the heating unit is used as the heat source for gasification of MeOH and HzO.

Electrode for Fuel Batteries TOYOTA JIDOSHA KK Japanese AppL 2000/243,406

An electrode for fuel batteries contains a cathode formed of C particles supporting Pt partides and TiO, particles, an electrolyte film and an anode. When generating electricity using H2 and 0 2 as fuel, UV rays of the wavelength 5 410 nm are irradiated on the cathode. The cathode reaction is accelerated by the W irradiation giving high output from the battery.

ELECTRICAL AND ELECTRONIC ENGINEERING Highly Temperature Stable Conductive Barrier SHARP KK European Apph. 1,054,440441

A highly temperature stable conductive barrier (1) comprises a substrate, a first barrier layer and an Ir- refractory metal-oxygen (Ir-M-0) composite hlm. (1) suppresses diffusion of Ir into the substrate so the Ir- M-0 composite film remains conductive, and resists peeling and hillock formation during high temperature annealing, even in 0 2 . (1) is used for an electrode of a ferroelectric capacitor, in nonvolatile metal/ferro/ metal/insulator/Si (MFMIS), DRAM, etc., devices.

Ruthenium and Platinum Organometallics TANAKA KIKINZOKU KOGYO K.K. Worki&pL 00/58,245

Ru and Pt organometallic compounds (1) are used for forming Ru, Ru oxide or Pt thin hlm on a substrate by organometaJlic vapour phase epitaxy. Thin film of excellent thermal stability can be deposited at constant rates. (1) are used as electrode materials in semi- conductor devices. Downsizing current in electrical apparatus is achieved.

Giant Magnetoresistive Stack SEAGATE TECHNOLOGY LLC worki &pL 00/63,714

A giant magnetoresistive (GhfR) stack for use as the read sensor (1) in a magnetic read head indudes a Ni-Fe-Cr seed layer; a free layer of ferromagnetic material having a rotatable magnetic moment; a ferromagnetic pinned layer of fixed magnetic moment; a Cr-Mr-Pt pinning layer adjacent to the latter; and a nonmagnetic spacer layer between the free and pinned layers. (1) exhibits a GMR ratio of 2 12%, the highest ever reported in simple spin valves. The Cr- Mt-Pt pinning layer has a high blocking temperature to stop exchange coupling disappearing.

Palladium-Containing Product SUPERIOR MICROPOWDERS LLC U.S. Patent 6,159,267

A particulate product (1) used as catalysts in the preparation of thick film paste, comprises high quality partides (0 .14 p) in which a polycrystalline metallic phase comprises > 10 wt.% Pd. Impaired film performance at high electrical conductivity is avoided. (1) has good dispersion of partides in the paste, and a low degree of particle agglomeration. (1) can be used in the manufacture of multilayer capacitors, multichips, flat panel displays, etc.

Multilayer Ceramic Capacitor KYOCERA CORP Japanese AppL 2000/223,352

A multilayer ceramic capacitor consists of a dielectric ceramic layer (1) using BaTiO3 as its major constituent, and an internal Ag-Pd electrode layer. When (1) is (lOC-a)BaTiO,.uBi2Ti20,, it contains (in mol. parts) a major constituent having a = 2.5-6.0, and in equivalents: 0.7-1.9 Nb in Nb205; 0.G1.9 Zn in ZnO; a rare earth element (RE) I 0.4 (0 is not included) in REzO~; and 0.4-8.3 Si in SO2. The multilayer ceramic capacitor has high dielectric constant, 2 2000, and improved thermal properties.

Multilayer Printed Wiring Board IRIDEN CO. LTD. Japanese Appl. 2000/252,622

A multilayer printed wiring board indudes roughen- ing surface on each conductive Cu pattern formed on corresponding resin insulating layers, with 0.5 mg m-’ Pd atoms being distributed between the patterns. The exfoliation of the conductor circuit (1) is eliminated or reduced and the migration of Cu between (1) at high temperature and high humidity is suppressed.

The New Patents abstracts have been prepared from material published by Denvent Information Limited.

Plafinarn Metab Rev., 2001,45, (2) 100

Johnson Matthey Technology Review · UK ISSN 0032-1400 PLATINUM METALS REVIEW A Quarterly Survey of...

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