Cyclohexane dehydrogenation over a strained-layer [formula omitted] catalyst

Abstract

The present studies are part of a continuing effort to identify those properties of a bimetallic system which can be related to its special catalytic properties. The specific model system of Cu and Ru was chosen due to the immiscibility of these two metals as well as the pivotal role played by this metal pair in historical bimetallic studies. The immiscibility of these two metals facilitates coverage determination by temperature-programmed desorption (TPD) and circumvents the many complications associated with the assay of alloy surface composition. The results are discussed from previous studies which have addressed the geometric and electronic structure of Cu overlayers on Ru(0001), the adsorption of CO and H/sub 2/ on submonolayer-to-multilayer deposits of Cu, as well as the measurement of the high-pressure kinetics of the methanation and ethane hydrogenolysis reactions on this model bimetallic catalyst. These results suggest that Ru specific rates for methanation and ethane hydrogenolysis on supported Cu/Ru catalysts approximate those values found for pure Ru. As a consequence, the rates for the cyclohexane dehydrogenation reaction on supported Cu/Ru, similarly corrected, must exceed those specific rates found for pure Ru. (The uncorrected specific rates for the supported Cu/Ru system remain essentially unchanged upon addition ofmore » Cu to Ru.) An activity enhancement for cyclohexane dehydrogenation in the mixed Cu/Ru system relative to pure Ru is most surprising given that Cu is less active for this reaction than Ru. In this note, the authors report just such an activity enhancement for the addition of Cu to a model Ru(0001) catalyst. 16 references.« less