Heterogeneous Catalysis in the Liquid Phase

The number of parameters affecting the rate and possibly the mechanism of a liquid phase, heterogeneously catalysed reaction is very much larger than that for the analogous gas phase reaction. The hydrogenation of two alkynes has been studied using a palladium oxide catalyst, in a number of solvents, in order to discover the effect of the latter upon the rates of reaction. It was hoped that results of general applicability to other liquid phase heterogeneously catalysed systems might be obtained. In this context, surface- and diffusion-controlled regimes have been identified, pronounced solvent effects were observed and attempts have been made to measure hydrogen concentrations in solution under reaction conditions.