Supported “bimetallic cluster” catalysts

Abstract

Silica-supported ruthenium-copper and osmium-copper catalysts have been investigated for the hydrogenolysis of ethane to methane and for the dehydrogenation of cyclohexane to benzene. Cyclohexane also exhibits a hydrogenolysis reaction on these catalysts, yielding methane as the predominant primary product. The ruthenium or osmium concentration in the catalysts was held constant at 1 wt%, while the atomic ratio of copper to ruthenium, or copper to osmium, was varied from 0 to 1. Despite the low metal concentration and attendant high metal dispersion, and the fact that copper is virtually totally immiscible with ruthenium or osmium in the bulk, the incorporation of the copper inhibited markedly the specific activity of ruthenium or osmium for hydrogenolysis. The specific activity for dehydrogenation of cyclohexane to benzene was affected very little. It is proposed that highly dispersed “bimetallic clusters” of ruthenium-copper and osmium-copper exist on the carrier.