The stoichiometry of hydrogen and carbon monoxide chemisorption on alumina- and silica-supported nickel

Abstract

Adsorption stoichiometries of H 2 at 298 K and CO at 190–298 K on alumina- and silica-supported Ni catalysts prepared by impregnation and precipitation techniques were investigated. In the case of alumina-supported nickel catalysts the metal loading was varied from 0.5 to 23 wt% in order to study the effects of metal-support interactions. Ni SiO 2 catalysts were prepared by both impregnation and precipitation techniques to determine effects of catalyst preparation. Room-temperature H 2 adsorption on alumina- and silica-supported nickel occurs with a stoichiometry of one hydrogen atom per surface nickel atom as determined by chemisorption, X-ray diffraction, and electron microscopy. CO adsorption is considerably more complex, the stoichiometry of which varies with equilibration pressure, temperature, metal crystallite size, and metal loading. Formation of nickel carbonyl and substantial amounts of chemical and physical adsorption of CO on the support provide additional complications.