Catalytic vapor-phase hydrogenation of acetylene in a stirred reactor.

Abstract

The hydrogenetaion of acetylene has been studied over pumice supported nickel, palladium and platinum catalysts, in a stirred flow reactor, and the effect of several variables upon the activity and selectivity of the catalysts has been examined. Concentration and temperature gradients over the catalyst surface were eliminated by the use of stirring in the reactor. It has been found that the selectivity of the reaction depended on temperature, feed ratio and the atomic number of the catalyst metal. The order of selectivity over the metals is palladium>nickel>platinum when the feed ration is less than 2. For feed ratio greater than 2, the order becomes nickel>palladium>platinum. The change in the order of selectivity over the metals is related to the "transition phenomenon", a manifestation of changes in the kinetic form of the reaction. While nickel showed the transition phenomenon at a feed ration of 2.111 at 90°C, and platinum at feed rations of 1.116 at 100.5°C, 1.473 at 79°C and 2.365 at 61.5°C, no such phenomenon was observed over palladium for the conditions studied.