PUMICE-SUPPORTED NICKEL-CATALYSTS - STRUCTURAL AND REACTIVITY STUDY IN THE HYDROGENATION OF CO

A series of nickel catalysts supported on pumice was prepared by preci pitation and impregnation techniques. The influence of the calcination and reduction temperatures on the structural properties such as latti ce parameters and particle dimensions of the oxide precursors and of t he reduced catalysts was investigated by X-ray diffraction measurement s. The effect of structural changes on the catalytic activity in the h ydrogenation of carbon monoxide has been evaluated. The turnover frequ encies, as well as product distributions, are discussed in terms of th e influence of the support properties and of its interaction with the metal. Changes of the C2+ yield over CH4 yield ratio versus nickel dis persion are attributed to the presence of the alkali ions in the suppo rt structure. The catalytic performance of the catalysts does not chan ge after 15-18 h time on stream. Indeed, the X-ray diffraction and pho toelectron spectroscopy analysis of the catalysts, before and after re action, excluded sintering of the metal particle, as well as coke form ation. (C) 1997 Academic Press.