SOLID BASE CATALYSTS FOR MERCAPTAN OXIDATION

Aqueous alkali can be completely replaced in the mercaptan oxidation r eaction by incorporating solid basic materials into the catalyst formu lation. The ability to use a solid oxide base to replace aqueous alkal i will have a positive environmental impact because aqueous alkalis, s uch as caustic, are becoming a serious disposal problems for petroleum refiners and chemical manufacturers. The basic oxide system used cont ains cobalt phthalocyanine (CoPc) supported on a metal oxide solid sol ution (MOSS). Although active for mercaptan oxidation, this catalyst d oes not meet the lifetime requirements for commercial application. Thr ee deactivation mechanisms have been identified: rehydration of the MO SS back to the layered double hydroxide (LDH) (because this rehydratio n causes a reduction in the basicity of these materials), deactivation by adsorption of heavy hydrocarbon species in the feed, and irreversi ble adsorption of acidic species from the feed. Knowledge of the deact ivation mechanisms has allowed the design of a process that meets the required catalyst lifetime requirements. This process represents one o f the first applications of solid base catalysis to a commercial proce ss. Catalyst performance, factors affecting deactivation, and methods of preventing deactivation are discussed. (C) 1998 Elsevier Science B. V. All rights reserved.