EFFECT OF SOLIDIFICATION CONDITIONS AND P D CONTENT ON STRUCTURE OF PD ADDED RANEY COPPER-CATALYSTS

Cu-70 at% Al alloys with various amount of Pd were solidified at diffe rent cooling rates and structures of the as-solidified alloys and cata lysts made by leaching Al from them were examined by SEM, DSC and X-ra y diffraction as a basic study for improvement of the catalytic activi ty of Raney copper catalysts for the hydration reaction of acrylonitri le which is important for production acrylamide. The specific surface area of the catalysts were measured by the BET Ar-absorption technique . The activity of the catalysts was evaluated by the conversion ratio from acrylonitrile to acrylamide by the hydration reaction. The result s are as follows. (1) In the conventional slowly solidified alloys, mo st of the added Pd was distributed in primary epsilon phase and its so lubility in the theta phase was quite few. On the other hand, in the r apidly solidified alloys, the formation of the primary epsilon phase w as almost suppressed and Pd was supersaturated in the theta phase. (2) Raney copper with soluted Pd was newly obtained by leaching the theta phase with Pd. This suggests that the rapid solidification process is an effective process to get new catalysts. (3) Specific surface area of Raney copper produced by leaching rapidly solidified alloys increas ed with Pd content. It was about 3 times higher in the 1.5 at%Pd alloy than that in the Pd-free alloy. (4) The catalytic activity of 1.5 at% Pd catalysts showed a maximum, but its value per unit specific surface area decreased with Pd content.