Noble Metal Ionic Catalysts

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Noble Metal Ionic Catalysts by Solution
Combustion method for Auto-Exhaust Catalysis

• P. Bera
• K. Nagaveni
• Arup Gayen
• Sounak Roy
• S. Prakash
• Tinku Baidya
• Sudhanshu Sharma
• Gargi Dutta
• Asha Gupta
• Preetam Singh
• Baskar Mukri

M. S. Hegde Solid State and Structural Chemistry
Unit Indian Institute of Science Bangalore
Prof. K. C. Patil Prof. M. Giridhar
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Langmuir Hinshelwood Mechanism
Pt
IRVING LANGMUIR 1932 Nobel Laureate in Chemistry
for his discoveries and investigations in
surface chemistry
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Active Sites on Pt Metal Particles
6 nm Pt particle Total no. of Pt atoms
13500 No. of surface Pt 2700
2700/13500 1/5 Only 1/5 th Pt atoms available
for Adsorption. If all Pt atoms are
utilized, Rate will be higher by 5 times.
This can be achieved by dispersing Pt as Pt2
ions in a reducible oxide support such as CeO2,
TiO2 This means Pt ions should become active
sites.
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Basis of mono metal - Ionic catalysts
CuO CO ? Cu CO2 But Cu O2 ?
CuO PdO CO ? Pd CO2 Pd
O2 ? PdO Therefore, CuO, PdO, PtO
etc., are not catalysts
Ce1-xPd2xO2- x y CO ?
Ce1-xPd0xO2-2x y CO2 Ce1-xPd0xO2-2x
y/2 O2 ? Ce1-xPd2xO2- x
--------------------------------------------------
--------- y CO y/2 O2 ? y
CO2 Therefore, Ce1-xPdxO2- ? should
become catalytic !

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Ce0.98Pd0.02O1.98
CeO2
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Solution combustion method Patils Method
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Single phase oxides substituted with noble metal
ions
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Observed, calculated and difference XRD patterns
of 5 Cu/CeO2
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Observed, calculated and difference XRD patterns
of 1 Pt/CeO2
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Rietveld Refined XRD of 2 atom Pd/CeO2
Ce0.98Pd0.02O2-? (??0.02)
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(c)
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(a) Pt(4f7/2,5/2) XPS of Pt metal (b) 1Pt/CeO2
(C), 2Pt/ CeO2 and (d) 800 0C heated 2
Pt/CeO2.
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CO adsorption on Ce0.99Pt0.01O2 and Pt0/Al2O3
J. Catalysis 196, 293 (2000)
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Temperature Programmed Reaction System
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TPR Temperature Programmed Reduction System
CuO H2 ? Cu H2O 1 mg 0.28 cm3 H2
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TPR Hydrogen Uptake Study
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Origin of OSC Gargi Dutta et al. Chem.
Mater., 18, 3249 (2006)
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2CO O2 ? 2CO2
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Rate of conversion Reaction
CO O2 ? CO2 Rate (moles g-1
sec-1) xF/w Where x
Fractional conversion F
(flow rate) moles sec-1
w wt. of catalyst, g
TOF (Sec-1) Rate/Moles of M
/g-catalyst Reaction Kinetics M. Giridhar
Catalyst
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CO oxidation by O2
CeO2
2 Pd imp CeO2
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CO oxidation by O2
CeO2
2 Pd imp CeO2
Ce0.98Pd0.02O2-?
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CO oxidation by O2
CeO2
2 Pd imp CeO2
Ce0.98Pd0.02O2-?
Ce0.73Ti0.25Pd0.02O2-?
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CO oxidation by O2
CeO2
2 Pd imp CeO2
Ce0.98Pd0.02O2-?
Ce0.73Ti0.25Pd0.02O2-?
Ti0.99Pd0.01O2-?
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CO oxidation by O2
CeO2
2 Pd imp CeO2
Ce0.98Pd0.02O2-?
Ce0.73Ti0.25Pd0.02O2-?
Ti0.99Pd0.01O2-?
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Higher the ionicity of Pd2 ion, higher
the rate and lower the activation energy
Dalton Tr. 2008
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Photo-catalysis CO O2 CONO to N2 CO2 NO
dissociation
Catalyst Ti1-xPdxO2-? High Pressure Mercury
Vapour Lamp 125 W.
Sounak, Giridhar, Ravishankar and Hegde, J.
Phys. Chem. 2007
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Implementation to Exhaust applications
Fresh Honeycomb
1 Pt/CeO2 coated
After reaction
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Three Way Catalysis with Monolith Catalyst
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Sudhanshu and Hegde
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Hydrogen Spillover
Gargi Dutta, Umesh Wagmare, Tinku and Hegde,
Chem. Mater. 2007
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LH Mechanism
Red-Ox sites Mechanism
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Water gas shift reaction 9 CO and 80 H2
CO H2O ? CO2 H2
Catalysis Letters 96 (2004) 213
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WGS Reactor
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Conclusions
?
Catalyst cartridge

• Mono-metal ionic Auto Exhaust catalysts
• New Oxygen storage materials Ce1-xTixO2,etc.
• Hydrogen spill-over
• Hydrogen-oxygen recombination catalyst
• New Electro catalysts
• Organic synthesis catalysts
• WGS catalysts for hydrogen
• Bimetal ionic catalysts PtPd, PtRh
• Catalyst for Heck coupling reactions