Activity and Selectivity Maps

Abstract

This chapter focuses on the more general description of trends in catalysis. Various reactions that proceed via the dissociation of diatomic molecules can have drastically different overall reaction energies. It is therefore often very useful to write the microkinetics in terms of the approach to equilibrium instead of the product pressure and reaction energy. Ammonia synthesis is an example of a process where activation of the reactant (N2) is rate determining for the most interesting catalysts. The chapter introduces a method that provides the simplest possible conceptual framework for analyzing microkinetic models of heterogeneous reactions, the so-called Sabatier analysis. Usually, a high selectivity toward the desired product is wanted, and the chapter shows how selectivity maps can be generated from activity maps where different competing reactions are taken into account.