Catalytic cracking, general regeneration

Although catalytic cracking processes differ in details of equipment and method of carrying out the reactions, the chemistry is basically the same in all cases. It is convenient, therefore, to discuss the effects of operating variables and the fundamentals of catalytic cracking and regeneration in general, and merely to point out instances where the effects differ from one process to another. 

APPLICATIONS OF FLUIDIZATION. Extensive use of fluidization began in the petroleum industry with the development of fluid-bed catalytic cracking. Although the industry now generally uses riser or transport-line reactors for catalytic cracking, rather than fluid beds, the catalyst regeneration is still carried out in fluid-bed reactors, which are as large as 30 ft in diameter. Fluidization is used in... 

These effects are important and facilitate the transport of heat and mass transfer, in most cases. In general, particles are dragged and they can recirculate within the bed by a process called regeneration. For example, process for catalytic cracking of petroleum. 

Deactivated catalysts are reused after adequate regeneration processes either on-site or off-site, when possible and economical. Important examples are catalytic cracking (FCC), naphtha-reforming and HDS catalysts. The generation process to be employed differs depending on the kind of catalyst and cause of deactivation. In general carbon deposits are burnt off by air and metal deposits are removed by chemical treatment such as washing with sulfuric acid. Redispersion of sintered metal particles on support is sometimes possible. 

The oxidation processes are being abandoned mainly because of the reduction in octane number that occurs. The many processes have been compared by Happel, Cauley, and Kelley, and althou the improvement by various processes is dependent upon the particular atuation, the general improvement is as indicated in Table 10-1. The catalytic processes give the best octane number, but they are more expenave d when applied to cracked gasolines the cost mounts rapidly becauE the catalyst must be regenerated frequently. 

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