Studies of the effect of calcination on the dispersion and reduction of nickel supported on alumina by X-ray photoelectron spectroscopy, X-ray diffraction, chemisorption and catalytic activity

Abstract

The influence of calcination temperature on alumina and on alumina-supported nickel has been systematically studied. Identification of the nickel species has been made using the techniques of X-ray photoelectron spectroscopy (X.p.s.) and X-ray diffraction (X.r.d.). Hydrogen and oxygen adsorption measurements were used to calculate the dispersion and crystallite size of the metal. Calcination of γ-alumina between 873 and 1073 K, before loading the metal, reduces the interaction of the metal and support, thereby increasing the area of metal available for hydrogen adsorption and for the hydrogenation of benzene. X.p.s. and X.r.d. indicate the presence of surface and bulk NiAl₂O₄ on catalysts calcined at temperatures > 873 K. Benzene hydrogenation is a facile reaction and depends directly on the available metal area, irrespective of the nickel content of the catalyst.