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1200255 
Journal Article 
CARBON-MONOXIDE ADSORPTION AND HYDROGENATION ON CU-RH SIO2 CATALYSTS 
Krishnamurthy, R; Chuang, SSC; Ghosal, K 
1994 
1 
Applied Catalysis A: General
ISSN: 0926-860X
EISSN: 1873-3875 
Elsevier 
114 
1 
109-125 
WOS:A1994NZ05300007 
The effects of copper on carbon monoxide adsorption and carbon monoxide hydrogenation over Rh/SiO2 have been studied. Copper decreases the activity for carbon monoxide hydrogenation and the rate of formation of methane, C2 and C3+, hydrocarbons. The selectivity for C2 oxygenate formation shows a slight variation with addition of copper. Cu-Rh/SiO2 catalyst with copper-to-rhodium ratio of 1.0 exhibits a high initial methanol selectivity which decreases with reaction time. The use of ethylene hydroformylation as a probe reaction shows that addition of copper causes little variation in carbon monoxide insertion activity; the propionaldehyde selectivity at copper-to-rhodium ratio of 0.05 is higher than that for the other catalysts studied. In situ infrared study reveals that copper blocks the formation of bridged CO. However, blockage of bridged CO site does not lead to enhancement in carbon monoxide insertion as observed with Ag-Rh/SiO2 and sulfided Rh/SiO2 catalysts. The lack of effect of copper promotion on carbon monoxide insertion can be attributed to a high hydrogenation activity of copper and a possible electronic interaction between copper and rhodium leading to a reduced rhodium surface that is less active for carbon monoxide insertion than the oxidized rhodium. The difference observed in the infrared spectra of adsorbed carbon monoxide at 303 K and 513 K in the presence and absence of reactants shows that carbon monoxide induces surface reconstruction at 513 K. Results of catalyst characterization at 303 K can not be extrapolated to elucidate the state of catalyst surface under reaction conditions. 
ADSORPTION; CARBON MONOXIDE HYDROGENATION; COPPER; ETHYLENE HYDROFORMYLATION; INFRARED SPECTROSCOPY; OXYGENATES; RHODIUM SILICA; SELECTIVITY 
IRIS
• Methanol (Non-Cancer)
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