Active Nonmetallic Au and Pt Species on Ceria-Based Water-Gas Shift Catalyst

Qi Fu, Howard Saltsburg, Maria Flytzani-Stephanopoulos

Laras Wuri Dianningrum

Term paper presentation

June 11st , 2012

Main Finding

Traditional assumption: catalyst reaction involving structure of metallic particles

Water-gas shift reactionCO+H2OCO2+H2

Au and Pt nanoparticles have no important role in WGS reaction over Ce-based catalyst

non-metallic activity of Au and Pt

Physical properties of catalysts

DP : Deposition-precipitationCP : CoprecipitationIMP : ImpregnationUGC: Urea gelation precipitation

Catalyst preparation

WGS Kinetic Rate

Commercial

catalyst G-66A

Au free

Ea: same for parent & leached catalyst (47.8 kJ/molDP,36.8 kJ/molCP)

WGS Kinetic Rate

Ea: same for parent & leached catalyst (74.8 kJ/mol)

Temperature Programmed Reaction Analysis

“Transient light-off curves “Light-off T was lowest for catalyst which contained lowest amount

of Pt

The removed Pt was not important

XPS AnalysisOxidation

states

• The existence of ionic phases (Au+1,+3 and Pt+2,+4) both before & after leaching• The complete removal of metallic Au/Pt nanoparticles after the leaching step• No Ce or La loss took place during leaching (also verified by ICP and HRTEM)

XPS AnalysisOxidation state

CO-TPR AnalysisIdentified

oxygen species

• First CO2 peakO2 adsorbed on metallic Au

• Ob peaks are similar for all

samples

• Os1 and Os2 peaks for Au-CL are

greatly increased

Au increases O2 surface amount in

Ceria

Conclusion

Au and Pt nanoparticles have no important role in WGS reaction over Ce-based catalyst.