Effects of preparation variables on characteristics of nickel impregnated alumina catalysts with low nickel contents.

Abstract

Chemistry, morphology, and activity of impregnated nickel/alumina catalysts with low nickel contents were studied using thermal gravimetric analysis (TGA), electron probe micro analysis (EPMA), X-ray diffraction (XRD), transmission electron microscopy (TEM), and hydrogenation of benzene. Total nickel content, drying condition, and support particle size were investigated to discuss their effects on the extent of reduction to nickel metal, the distribution of nickel particle size, and the catalytic activity. Both the extent of reduction and nickel particle size increased with increasing total nickel content. The nickel particle size was controlled only by the local nickel content, being independent of drying condition, support particle size, and nickel concentration profile within the bulk catalyst. Catalysts containing less than 0.1wt% total nickel could reduced the nickel almost not at all, and showed a much lower reaction rate per unit mass of total nickel than those containing more than 0.1wt% total nickel.