MAGNESIA-SUPPORTED NICKEL-CATALYSTS .1. FACTORS AFFECTING THE STRUCTURE AND MORPHOLOGICAL PROPERTIES

The effects of calcination and reduction temperature on the metal dispersion of MgO-supported Ni in the ranges 400-800°C and 300-800°C, respectively, have been systematically evaluated by hydrogen chemisorption measurements and comparison has been made with a NiOMgO physical mixture. The role of the bulk NixMg(1 - x)O solid solution in controlling NiO reducibility and the metal dispersion of Ni/MgO has been ascertained by XPS and ISS investigations. A mechanistic model accounting for the nickel oxide dispersion across the MgO support and the consequent formation of the bulk NixMg(1 - x)O solid solution has been proposed. A linear relationship between the mean particle size and the reduction temperature, the slope of which increases with Ni loading (2.8-18.0 wt%), has been found. A "multilayer arrangement" of Ni precursor on the support is discussed. © 1991.