INTERACTION OF CARBON-MONOXIDE WITH SUPPORTED NICKEL-CATALYSTS

The interaction of carbon monoxide with Ni/SiO2, Ni/Al2O3 and Ni/TiO2 catalysts Was studied by temperature-programmed desorption (TPD) of pre-adsorbed carbon monoxide. The TPD spectra exhibit a number of CO and CO2 features reflecting various processes occurring during the interaction. Silica and alumina have a moderate effect on the spectra for supported nickel. In contrast, titania significantly affects the spectra, and the degree depends on the extent of reduction of titania and thus its ability to accept/donate oxygen. Analysis of the spectra obtained indicates that silica, alumina and non-reduced titania lower equally, by about 40-degrees-C, the temperature of dissociation of CO pre-adsorbed on supported nickel; on the other hand partially reduced titania lowers the dissociation temperature by ca. 100-degrees-C, by accepting the oxygen that is released. The influence of silica, alumina and non-reduced titania on the rate of CO dissociation is ascribed to the formation of a perturbed nickel surface at the nickel-support boundary; at the same time the effect of partially reduced titania on the dissociation is ascribed to joint action of perturbed nickel surface and the oxygen accepting TiO(x) species at the boundary.