Fusion of Catalysts Containing Precious Metals Presentation Overview

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Fusion of Catalysts Containing Precious Metals

By: Philippe Daigle, M. Sc Chemist, Corporation Scientifique Claisse

ASTM Committee D-32St. Louis, MO, Tuesday April 21 2010

© All rights reserved – Claisse 2009 2

1. Analytical problems of catalysts with precious metals

2. Basics of fusion

3. Fusion approach – method development for XRF

4. Results - XRF

5. Conclusion

Presentation Overview

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� Wide variety of composition � Only few primary standards available� Need to do secondary in house standards

� very costly and time consuming

� Fire assay for precious metal� Can be a long process to obtain valuable

results for every element present in the sample


1. Analytical problems - XRFXRF

Problems with PPT:� Matrix effects� Particle sizes effects� Mineralogical effect� Need for matrix match standards� Multiple calibration curves for PPT need to be

generated in order to get good results� Costly and time consuming

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Penetration depths are affected by both grain size and “mineralogical” composition, density of material distribution ofphases (segregation) and by overall sample composition.

Particle size

Phase"2"

Phase"1"

Penetration DepthDepth of sample effectivelycontributing to measuredintensity


Mineralogical effect on XRF intensities

Typical Fe line intensities for Fe when present in same concentration, in same particles size, but as different mineralsin a sample (different densities).

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1. Analytical problems - XRFXRF

Problems with borate fusion:� Works only with fully oxidized element� Precious metals are usually not in fully

oxidized form� Uses 95%Pt/5%Au crucible� Contamination?� Will the precious metals get into solution?� Will we be able to obtain a good fused disk?


Then why try it by fusion for XRF?

� To have better precision and accuracy� To make synthetic standards� To avoid re-doing calibration curves when

sample change� No mineralogical, nor particle, nor matrix

effects� Less calibration curves to be done� Time and cost saving

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PPT vs Fusion


1. Analytical problems - ICPICP

� Acid digestion� Concentrated acids and even HF

� Not sure if complete digestion of sample or not

� Time consuming

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Why fusion for AA/ICP?

� High analytical accuracy� Complete dissolution of the sample� Time and Money saving technique� Complete dissolution in less than 10 minutes� Less expensive in labor costs� Production: optimizes the use of raw materials &

improves and stabilizes the product quality� To avoid working with lots of concentrated acid

�� Will the precious metal get into solution?Will the precious metal get into solution?

Fusion for AA and ICP



2. Basics of fusion


4. Results - XRF

5. Conclusion


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2. Basics of Fusion

2- Add the sample

1- Weigh the borate flux into the crucible

Heat while agitating

All oxides but ONLY oxides are soluble in molten borate

3- Add additive


Casting

Free cooling

Forced cooling

Bead retrieval

Acid

XRF AA&ICP

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Definition

� Fully oxidized element: Oxidized element that has reached its highest stable oxidation state (Fe2O3, CuO, Cr2O3).

� Pure oxides: ZnO, Cu2O, PbO, Al2O3, SiO2, ZrO, TiO2…

� Carbonates: CaCO3, MgCO3…� Sulfates: BaSO4, CaSO4…

� Nitrates: NaNO3, KNO3…


DEFINITIONS

� Semi oxidized element: Oxidized element that hasn’t reached its highest stable oxidation state (FeO, Cu2O, CrO).

� Non oxidized element: Element in its elemental or metallic form (Fe,Cr, Pt, Pd, Rh).

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If sample is not oxidized?



2. Basics of fusion


4. Results - XRF

5. Peroxide Fusion/oxidation for ICP

6. Conclusion


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Problem with catalyst containing Pt:Problem with catalyst containing Pt:� PtO2 and the less common PtO both

decompose upon heating1

� Not stable as oxide at temperature >450°C2

� In reduced form it agglomerates and alloys with the wall of the crucible2

1- Lagowski, J. J., ed (2004). Chemistry Foundations and Applications. 3. Thomson Gale. pp. 267–268. ISBN 0-02-865724-12- Drew, A.R. XRF analysis of automative catalysts by fusion/flux, ICDD 2002, Advances in X-ray Analysis, Vol 45

Fusion approach - method development for XRF



To be careful:To be careful:� Keep oxidizing condition all through the

fusion process� Sample must not get in contact with the

crucible wall� Avoid any agglomeration of sample� Reduce possible contact with the wall of the

crucible

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Strategy:Strategy:� Make sure we have oxidation condition all

through the fusion � Keep rotation slow



What was tried:What was tried:� Choice of oxidizer

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• Most popular for dry oxidation

• Decompose into NxOy and alkaline oxides

• NH4NO3 decomposes entirely into NxOy

Nitrate Oxidizer


• Chemical and physical effect (carbonates)

• Decompose into COx and alkaline oxides (carbonates)

• Iodate and iodate-carbonate are promising oxidizers

Carbonates and Iodates oxidizer

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What was tried:What was tried:� Choice of oxidizer

� NaNO3� Crystallized or undissolve� NaNO3 and Li2CO3� Worked with some samples� LiNO3 and Li2CO3� Worked with some samples

� Final choice was� LiNO3 mp: 255°C decp: 600°Cor � NaNO3 mp: 308°C decp: 380°CAND � Li2CO3 mp: 720°C decp: 1310°C

� Amount of oxidizer



What was tried:What was tried:� Choice of flux (%LiT/%LiM/%LiBr):

� 49.75/49.75/0.5� crystallized � 67/33/0,5 � crystallized� 99.5LiT/0.5 � Good

� Fusion method:� Need oxidation step first� Low rotation until dissolution

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2. Basics of fusion


4. Results - XRF

5. Conclusion



Fusion method and sample prep – Catalyst with Pt only

� First trial was with one sample only� Alumino-silicate catalyst with Pt

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Fusion method and sample prep� n=8� In a Pt/Au crucible:

1. Weigh 0.45g of LiCl2. Weigh 10g of Flux (LiT/0.5%LiBr) 3. Weigh 2g of LiNO3 4. Weigh 1.0g of Li2CO3 5. Weigh 0.15g of sample 6. Mix carefully the 1st cm with a teflon rod

to make contact between the oxidizers and sample

Flux bed

Sample on top to keep it away from crucible


Fusion method and sample prep - Apparatus

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0

20

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0 2 4 6 8 10 12 14 16Time (minute)

Agi

tatio

n (%

) C

ruci

ble

angl

e (o

) C

oolin

g (%

)

AgitationCrucible angleCooling

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0 2 4 6 8 10 12 14 16 18

Time (minute)

Tem

per

atu

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Precision Results – Catalyst with Pt only

General interpretation of the results/method:� Blank made with flux/oxidizer showed no Pt� Precision is OK (8 fused disks)� Accuracy???

� Next step, try with a NIST Standard…

SiO 2 Fe 2 O 3 Pt Al 2 O 3 CaO CuO MgOAverage 40,48% 4,88% 1,85% 12,36% 17,68% 1,80% 17,54%SD 0,94 0,19 0,10 0,45 0,59 0,07 0,54RSD (%) 2,33 3,93 5,34 3,67 3,35 4,15 3,11

Catalyst with Pt

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Fusion method and sample prep – Catalyst with Precious metal

� Second trial was made with 6 different samples containing various amount of Pt, Pd and/or Rh



Fusion method and sample prep

� In a Pt/Au crucible: 1. Weigh 1g of Flux (LiT/0.5%LiBr) 2. Weigh 0.75g of NaNO3 3. Weigh 0.75g of LiCO3 4. Weigh 0.2g of sample 5. Mix carefully6. Add on topp 5g of Flux

(LiT/0.5%LiBr)

Flux cover

Sample on bottom mixed with part of the flux and oxidizer

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Fusion method and sample prep - Apparatus



0

10

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0 2 4 6 8 10 12 14 16 18

Time (minute)

Tem

per

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0

20

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0 2 4 6 8 10 12 14 16Time (minute)

Agi

tatio

n (%

) C

ruci

ble

angl

e (o

) C

oolin

g (%

)

AgitationCrucible angleCooling

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Pt

y = 0,463x + 0,6068R2 = 0,994

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1

2

3

4

5

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0 2 4 6 8 10 12

% PtO2 in sam ple

kcp

s

Results - Pt linearity

� Curves made with 3 samples containing different amount of Pt

� Pt gets dissolves into Borate flux

� Measurement made in Std-less mode

� Linearity is OK� Blank showed Pt

� No standards to test the recovery


Results - Pd linearity

� Curves made with 2 samples containing different amount of Pd

� Pd gets dissolves into Borate flux

� Measurement made in Std-less mode

� Linearity is OK� Blank showed Pd

� No standards to test the recovery

PdO

y = 0,4079x + 0,2079R2 = 0,9973

0

0,5

1

1,5

2

2,5

3

3,5

0 0,5 1 1,5 2 2,5 3 3,5 4 4,5 5 5,5 6 6,5 7 7,5

% PdO

kcps

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Results - Precision

General interpretation of the results/method:� Blank made with flux/oxidizer showed small amount of precious metal

maybe because oxidation made at the bottom� Precision is OK for Pt and Rh, needs to be improved for Pd� Linearity for a calibration curves looks ok� Needs to be tried with standards and different catalyst type

Conc%

Average (kcps)

RSD Conc%

Average (kcps)

RSD Conc%

Average (kcps)

RSD

Blank 1 --- 0,587 --- --- 0,182 --- --- 0,131 ---Sample 1 3 0,07 0,483 1,64% 1,96 0,627 12,70% --- --- ---Sample 2 3 2,12 1,470 1,17% --- --- --- --- --- ---Sample 3 3 5 3,147 1,26% --- --- --- --- --- ---Sample 4 3 10 5,149 2,24% --- --- --- --- --- ---Sample 5 3 --- --- --- --- --- --- 0,580 0,320 3,28%Sample 6 3 --- --- --- 4,70 2,034 9,10% --- --- ---

Rh 2 O 3PdOPtO 2

Precious metal in catalyst

# replicate



2. Basics of fusion


4. Results - XRF

5. Conclusion


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5. Conclusion

� First trials made with catalysts containing precious metal showed promising results:

� Pt and Rh results are very encouraging� We are sure we can improves Pd results� Material completely dissolve in fused disks

� fusion works!!!

� Combination of oxidizers and good control of the fusions parameters are critical;

� Accuracy still has to be tested;� Method development is slowed by the difficulties to

get standards


5. Conclusion

� Next steps?� Try to improve Pd precision� The pursuit of the project requires working with

different types of standards catalyst and containing different amount of precious metals � To test recoveries� To test for versatility of the method

� Develop an application using borate fusion for ICP/AA analysis using matrix match standards

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Philippe Philippe DaigleDaigleCorporation Scientifique ClaisseCorporation Scientifique Claisse

Email: Email: [email protected]@claisse.comPh: 418Ph: 418--656656--64536453www.claisse.comwww.claisse.com

Thank you for your attention !Thank you for your attention !

Fusion of Catalysts Containing Precious Metals Presentation Overview

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