CHEMISORPTION AND INDUSTRIAL CATALYTIC PROCESSES

In recent years workers in the field of surface science have established the utility of their experimental techniques by in-depth investigations of simple adsorption systems, particularly the interaction of carbon monoxide with transition metal surfaces. Lately, attention has begun to shift toward areas of more directly practical interest, especially chemical reactions catalysed by metal and oxide surfaces. In this paper two commercial catalytic processes will be discussed in detail. Firstly, the conversion of synthesis gas (in this case a mixture of CO, CO2 and H2) to methanol over Cu/ZnO/Al2O3 catalysts and secondly the partial oxidation of ethylene to ethylene oxide using silver catalysts. In these processes, as in many heterogeneously catalysed reactions, the interaction between the gas phase species and the surface is important in determining the rate of product synthesis and the selectivity of the reaction. An understanding of the fundamental adsorption properties of such systems is clearly important for the elucidation of synthesis mechanisms and for the development of more efficient catalysts. The nature of the adsorption, desorption and surface reaction events involved in the two particular synthesis routes under consideration will be discussed and will be related to the global features of the commercial process.