METAL CATALYST DESIGN AND PREPARATION IN CONTROL OF DEACTIVATION

Catalyst life (with activity and selectivity) is one of the three essential properties of a practical catalyst, both in laboratory and industrial usage. For most catalysts in which the active phase is a metal, high activity requires a high metal surface area. In all cases, for long life, the metal surface area has to be maintained. The various modes of catalyst deactivation leading to loss of metal surface area are described (sintering, poisoning, coking, etc.). The choice of catalyst components for both active metal phases and for support phases is shown to be subject to thermodynamic and kinetic limits. Routes for the preparation of catalysts need to be and can be designed to give not only active, but also stable catalysts. Examples described include copper/zinc catalysts for hydrogenation/dehydrogenation reactions, iron catalysts for ammonia synthesis, nickel catalysts for hydrogenation reactions, automobile exhaust catalysts, and Raney catalysts.