Low Temperature Shift Catalyst

By:

Gerard B. Hawkins Managing Director, CEO

Conventional Hydrogen Plant

Low Temperature Shift

Purpose Chemistry Operating Conditions Catalyst Activity Poisons By-Product Formation Effects of Water Catalyst Requirements VSG-C111/1122 - Series

LTS - Purpose

Generate H2 from steam - improve plant efficiency

Convert CO to CO2 for easier removal • CO is converted to CO2 in two stages of

shift conversion LTS is the second stage of shift conversion to

generate H2

• Residual CO conversion - critical to operating economics

• Reduce CO levels to typically 0.3 mol% (dry)

LTS - Chemistry

CO + H2O ⇔ CO2+ H2 ∆H = -41.1 kJ/kgmol

• Reaction catalyzed by Cu for LTS • CO lowered from typically 3% to 0.3% • High conversion is favored by

– Low temperatures – High steam concentration

• Typically accomplished using copper on a zinc-alumina support

Cu

LTS – Typical Operating Conditions

SOR EOR Temp (°F) 356 - 392 410 - 446 CO (vol%) 3 – 5

Temp (°F) 410 - 518 CO (vol%) 0.2 – 0.3

CO + H2O CO2 + H2

Inlet

Outlet

Inlet temperature ≥ 27°F above dew point

LTS - Temperature Profile

Top Bed Depth

Bottom

Tem

pera

ture

Ageing

Movement

• Ageing mechanism is gradual poisoning

LTS - Catalyst Activity

Good, stable catalyst activity • Maximum conversion of CO to CO2 • High kinetic rate at low LTS inlet

temperatures Conversion limited to equilibrium Operational measure of activity:

• temperature gradient through catalyst bed

• higher activity gives steeper gradient

LTS - Catalyst Activity

Activity is NOT directly related to Cu content or Cu surface area • Cu content must be highly dispersed and

stabilised (hence content is not a good measure)

• Cu crystal phases and structure important to activity (therefore surface area is not a direct measure)

Only real test is in laboratory under faithfully reproduced plant conditions and on operating plants • Initial activity may not have any

relationship with long term activity retention

LTS – Catalyst Activity

ATE (approach to equilibrium) is usually very close • CO slip not impacted by activity for

most of catalyst life • Does not affect movement of

temperature profile through bed Minimum inlet temperature restricted by

dew point • Not always possible to reduce inlet

temperature to optimal value to take advantage of activity

Not the most important parameter!

LTS - Temperature Profile

Top Bed Depth

Bottom

Tem

pera

ture

Ageing

Movement

• Ageing mechanism is gradual poisoning Goal: Slow the rate of temperature profile

movement down the bed (poison resistance)

LTS – Catalyst Poisons

Sulfur • Powerful poison • Trapped by the catalyst as Cu2S and ZnS

Chloride • Severe poison • Reacts with copper and zinc to form

chlorides • CuCl formation provides a mechanism for

loss of activity by sintering

LTS - Mechanism of Sulfur Poisoning

ZnO

Cu

ZnO

Cu

Zn2+

Cu

ZnO

Cu

Adsorption on Copper Surface Mobility

Surface Sulphide Formation

Bulk Sulphide Formation

SS

ZnS

LTS - Chloride Poisoning

Chloride reacts with copper to form CuCl (mp = 430oC)

CuCl formation provides a mechanism for loss of activity by sintering

Requires well dispersed and stabilized copper to minimize the effect of chloride

Chloride Poisoning of LTS Catalysts

Chlorided LTS Non-chlorided LTS

Copper clusters normal size Copper clusters sintered

Lost surface area

Chloride Poisoning of LTS Catalysts

Chlorided LTS

Sintered Copper ball large surface area loss

Effect of Particle Size on Poisons Resistance

0

20

40

60

80

100

Cumulative Chloride Level

CO conversion (%)

0.3 - 0.6mm

0.6 - 1.0mm

1.18 - 1.4mm

1.4 - 1.7mm

•Poisoning reactions with H2S and HCl are strongly diffusion limited •Poisons resistance and activity can be increased by increasing the pellet geometrical surface area

LTS - By Product Formation

• Methanol – Effect quality of CO2

– Quality of process condensate • Environmental legislation • Increased treatment costs

– Odor in CO2 vent • Can produce amines • When vented can be a nuisance

– Other oxygenates such as ethanol, ketones

LTS - By Product Formation

• Methanol Formation CO2 + 3H2 <====> CH3OH + H2O

• MeOH increases with – High Temperatures – High inlet CO levels - increases LTS temperature rise – low S:C ratio – Low space velocity / catalyst bed volume

• MeOH production decreases rapidly in the first few months of LTS catalyst operation

• Condensate – If catalyst is operated at too low temperature

• Waste Heat Boiler Leaks – Wetting then evaporation reduces strength

significantly – Can cause catastrophic failure due to thermal

shock – Loss of activity due to blocking of active sites – Pressure drop increase

• catalyst break-up • boiler solids fouling catalyst

LTS - Effects Of Water

LTS - Effects Of Water

• Water will dissolve soluble poisons – wash poisons deep into the bed – Increase affected bed depth – accelerate change-out of the catalyst

Remember

CuCl2 is soluble in water!

Key Performance Requirements

Poisons Resistance • Self guarding capacity

Selectivity • Minimize by-product formation

(methanol) Activity

• Minimize CO slip • With minimal catalyst volume

Strength • Withstand upsets such as condensation

VSG-C111/112 Superior Poison Resistance

Low Methanol By-product Options High Activity High Strength

Extended Catalyst Life Short Load Potential to fit T/A Cycles

Maximize Hydrogen Production Address Environmental Concern

Resilient

Superior Poison Resistance

Improved Poison Retention using VSG-C111/112 series

High sulfur retention Typical = 1% at top & 0.1% at the bottoms

Impact of chloride poisoning on CO conversion

Extra Chloride Poisons resistance

Applications confirm expected activity for CO and low methanol.

Additional benefit is the enhanced ability to chloride guard.

• Caesium and potassium have the highest driving force for chloride.

• This is shown by the fact that CsCl and KCl will be formed at very low levels of HCl.

Equilibrium HCl Concentration

Chloride Guarding Properties of VSG-C111/112 series

• Very stable chlorides are formed Chloride Mp (oC) Bp (oC) CuCl 430 1490 ZnCl2 283 732 CsCl 645 1290 KCl 770 1500 subl

Mechanism of Chloride Resistance

ZnO

Cu

Adsorption on Potassium

HCl

CsCl ZnO Cs

Bulk Chloride Formation

K and Cs protect the Cu/ZnO lattice by preferentially reacting with and trapping chloride poison

Cu

Sulfur Poisoning & Surface Area

Competitors

VSG-C111/112

2 4 6 8 10 12 14 160

0.2

0.4

0.6

0.8

1

1.2

1.4

Sample Depth (ft)

Poison Level (%)

Cl (%)

S (%)

Poison Profile for VSG-C111, Chinese Hydrogen Plant

Sulfur & Chloride Retention of VSG-C111/112

= 13,000ppm!

Relative Impact of Activity and Poison

Base (VSG-C111) +20%act +20%poison

Low By-product Formation (Methanol)

Plant Performance Optimized alkali promoters to achieve

high activity for shift conversion while reducing methanol synthesis

--------VSG-C111 ---------VSG-C112 Plant Data

Laboratory Testing

Product Methanol Activity VSG-C112 0.18 Comp A low MeOH 0.26 Comp B low MeOH 0.33

High Activity

Activity Comparison (Laboratory)

Minimize CO slip

0.20

0.22

0.24

0.26

0.28

0.30

0.32

0.34

0 2 4 6 8 10

Time on-line (years)

CO

slip

Com petitor A

KATALCO 83-3XCom petitor C

---------- Competitor A ---------- VSG-C112 ---------- Competitor C

Case Study: Longer Life (1700 stpd China Ammonia Plant)

Previous competitive charge achieved only 3-yr life before high CO slip (> 0.3 mol%) when 4-yr was expected

Replaced with VSG-C112 and operating 5+ yrs with less than 0.25 mol%

$$$ Saved ~ $170,000 +

Avoided Unscheduled S/D +

12-month Extension on T/A

High Strength

Relative Strengths of Fresh and Reduced Catalyst

VSG-C112 series formulated to have high strength after reduction

VSG-C112 Competitor A Competitor B

Horizontal Crush Strength after Reduction and Condensing Steam

Conditions Compares relative strength of VSG-C112

and competitive low methanol products

VSG-C112

Conclusions

VSG-C112 excels over all products with • More than adequate activity • Poisons resistance at least equal to a

‘famous and soon to be obsolete’ guard material with claimed ‘unrivalled poisons resistance’

• The lowest by-product Methanol in the industry

So for long life, low CO slip, Low Methanol VSG-C112 is the winner

Catalyst Characteristics

VSG-C111 Copper oxide/Zinc Oxide/Alumina VSG-C112 As above, promoted by alkali metals

Lab Based Test Program

Ability of the Topsoe LSK Guard to withstand chloride poisoning relative to VSG-C112

Determined in the laboratory using an accelerated poisoning test.

In the test a guard layer of the catalyst sample is placed above a main bed of VSG-C111 catalyst and the CO conversion is measured using LTS gas containing very low levels (50 ppb in this case) of HCl.

Chloride resistance test rig LTS Feed gas

(60% H 2 , 21% N 2 , 16% CO 2 , 3% CO) with

50 ppb Chloride poison addition

Analysis of CO conversion

Standard bed

Test bed LSK

Analysis of CO conversion

Standard bed VSG-C111

Test bed VSG-C112

VSG-C111

Chloride poison test results % Conv vs Wt Cl addition (gms)

Run No PR133 - 50 ppb HCl addition

010

2030

405060

7080

90100

0 0.0005 0.001 0.0015 0.002 0.0025 0.003 0.0035 0.004 0.0045

Wt Cl addition (gms)

% C

onve

rsio

n

PR133B - U4676 Topsoe LSK PR133C - H1106K Std 83-3XVSG-C111

Chloride poison test results TOPSOE LK-823 and LK-821-2

1ppm HCl additionCharged as guard beds (0.2mls) above main beds Std 83-3 (0.4mls)

Main Bed SV ~ 127000

0

20

40

60

80

100

0 0.002 0.004 0.006 0.008 0.01 0.012 0.014 0.016 0.018 0.02

Wt Cl addition (gm)

% c

onve

rsio

n

PR59 - 83-3X PR59 - LK-823 PR59 - LK-821-2 PR59 - 83-3KVSG-C111

Overall comparisons Activity/selectivity on volume comparison

Catalyst Relative Activity(v/v)

Relative Methanol Make(v/v)

LSK 0.52 0.44

LK 821-2 1.20 0.88

VSG-C111 1.18 0.20

Competitive Summary

Laboratory Poisoning Data

Analysis of CO conversion

Standard bed

Test bed Cat B

Analysis of CO conversion

Standard bed

Test bed Cat C

LTS Feed gas (60% H2, 21%N2, 16% CO2, 3% CO)

with Chloride poison addition

Analysis of CO conversion

Standard bed VSG-C111

Test bed Cat A

Analysis of CO conversion

Standard bed

Test bed Cat D

VSG-C111 VSG-C111 VSG-C111

How do We Compare? Product Relative Poisons

Absorption * VSG-C111 1.0 VSG-C112 2.13

Comp A Guard ** 2.1 Comp A std 1.0

Comp A low MeOH 1.28 Comp B std ?

Comp B low MeOH 0.70 * Chloride pickup relative to VSG-C!!! measured by CO slip vs time and chloride analysis on spent material

** Guard with almost no sulfur capacity and very low activity