Chapter 10 Supported Mono- and Bimetallic Catalysts in Hydrocarbon Conversions

Abstract

Publisher Summary This chapter discusses the role of supported mono- and bimetallic catalysts in hydrocarbon conversions. The structure of the catalysts is considered based on the recent progress in the preparation of mono- and bimetallic carrier catalysts. The catalytic bimetal effects are illustrated by the reactions of hydrocarbons with hydrogen—that is, hydrogenation, dehydrogenation, dehydroisomerization, dehydrocyclization and hydrogenolysis. The coke deposited during the reactions, must be regarded as a modifier of platinum. The interactions of coke with the second metal are included. Some general aspects of the relationships between the preparation, structures and catalytic effects of bimetal catalysts in hydrocarbon conversions are outlined. Substantial progress has been achieved in understanding the different steps in the preparation and pretreatment. Hydrocarbon conversions at higher temperatures are accompanied by severe self-poisoning, caused by coke deposition. The catalytic effects of many second metals exhibit uniformity; negative under mild, positive under severe reaction conditions. These bimetal effects can be explained in terms of bimetallic clusters as the active sites. Selective conversions are only inhibited by second metals. Non-selective conversions can be classified by the accompanying reactions of C-C bond rupture and of self-poisoning coke deposition.