Using the M 4(M=Ru, Rh, Pd) clusters as models, chemisorption of CO at the top and bridge sites has been performed by Gaussian programs, at the DFT/LANL1DZ level. Metal CO bonding and the influence of CO bond after chemisorption CO have been studied, and the effects on the products of CO hydrogenation have been inferred. The calculations have shown that all the CO bonds are wakened after adsorption. Ru catalyst weakens C-O bond the most largely, Pd weakens C-O bond the least, and Rh lies between them. So it could be concluded that the products of CO hydrogenation have a trend to the hydrocarbons over the Ru catalyst, and the products are inclined to oxygenate over Pd, while there isnt obvious trend to the hydrocarbons and oxygenate on Rh.
By using OCMOSiH\-3(M=Ru, Rh, Pd) as models to imitate the chemisorption of CO on the silica\|supported catalysts, the geometries and frequencies have been performed for the complexes by Gaussian programs, at the B3LYP/LANL1DZ level. An influence of the C\_O bond has been studied and the support effects of silica are obtained. The support effects of silica make the CO frequency an upward shift, which means that the weakened degree of C\_O decreases and the bond strength of C\_O increases naturally compared to those of the non\|silica\|supported catalysts. So the products on the silica\|supported catalysts shift to the oxygenates.
