Catalytic reforming bimetallic catalysts

Introduction of zeolites into catalytic cracking improved the quality of the product and the efficiency of the process. It was estimated that this modification in catalyst composition in the United States alone saved over 200 million barrels of crude oil in 1977. The use of bimetallic catalysts in reforming of naphthas, a basic process for the production of high-octane gasoline and petrochemicals, resulted in great improvement in the catalytic performance of the process, and in considerable extension of catalyst life. New catalytic approaches to the development of synthetic fuels are being unveiled. 

Figure 5. Flow diagram of proposed hydrotreating/FCC refinery for Paraho shale oil. Ch is butanes and lighter use for H2 plant feed, gasoline blending, and refinery fuel Foul gas and water are treated to recover NHS ana sulfur. Low-pressure catalytic reformer uses bimetallic catalyst.

The ensemble control plays a role also in catalytic reforming on platinum or bimetallic catalysv. A good catalyst should have low activity for hydrogenolysis resulting in production of lower alkanes, and it should have a slow build-up of carbon overlayers to maintain stable activity for isomerization, dehydrogenation and dehydrocyciiration ... 

The total capacity of the semiregenerative units exceeded 5.0 million b/d while CCR units reached 3.8 million b/d. The simultaneous use of CCR technology and bimetallic catalysts has given UOP a unique position in the field of catalytic reformer process licensing. Recent catalyst formulations have improved both aromatic and reformate yields. UOP has improved the performance of the conventional platforming process by incorporating a CCR system. The process uses stacked radial-flow reactors and a CCR section to... 

The alloy catalysts used in these early studies were low surface area materials, commonly metal powders or films. The surface areas, for example, were two orders of magnitude lower than that of platinum in a commercial reforming catalyst. Hence these alloys were not of interest as practical catalysts. The systems emphasized in these studies were combinations of metallic elements that formed continuous series of solid solutions, such as nickel-copper and palladium-gold. The use of such systems presumably made it possible to vary the electronic structure of a metal crystal in a known and convenient manner, and thereby to determine its influence on catalytic activity. Bimetallic combinations of elements exhibiting limited miscibility in the bulk were not of interest. Aspects of bimetallic catalysts other than questions related to the influence of bulk electronic structure received little attention in these studies. 

This monograph describes research on bimetallic catalysts conducted at the Exxon Research and Engineering laboratories since the early 1960s. Much of the monograph is concerned with research directed toward the validation and elucidation of the bimetallic cluster concept. Some discussion is devoted also to the technological aspects of these systems, with emphasis on their application for the catalytic reforming of petroleum fractions. 

Bimetallic catalysts have had a major impact in industrial catalysis, notably in the catalytic reforming of petroleum fractions. As background for a discussion of the application of such catalysts in the reforming process, some of the major features of catalytic reforming are reviewed first. 

As far as the action of supported bimetallic catalysts is concerned, the main theories suggest either geometric and/or electronic effects to account for the improved catalytic properties. For instance, in platinum based naphtha reforming catalysts, the electronic modification of platinum particles may be induced by an interaction with an oxide layer of the promoter or by alloy formation. The electronic modification results in a change in the Pt-C bond strength of adsorp-... 

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