Temperature-programmed FT-IR study of the adsorption of CO and co-adsorption of CO and H 2 on [formula omitted

Abstract

The adsorption of CO and co-adsorption of CO and H 2 on Ni Al 2O 3 catalyst prepared by a distinct procedure were studied by means of FT-IR technique. The study shows that only one kind of CO adsorption site — the linear CO adsorption site — exists on the Ni Al 2O 3 catalyst used in present work. Temperature-programmed heating of CO adspecies in CO atmosphere reveals that the disproportionation of linearly adsorbed CO may occur at above 473 K. In H 2 + CO atmosphere, a new IR band centered near 1910 cm −1 emerges, the intensity of which increases and decreases concomitantly with that of the band centered about 2050 cm −1 with increasing temperature, indicating the occurrence of a new adspecies in the dynamic process of CO hydrogenation under reaction conditions. This new adspecies is tentatively ascribed to nickel carbonyl hydride species. The methanation of CO on Ni Al 2O 3 may occur via a mechanism involving the formation of nickel carbonyl hydride species.