Transalkylation dealuminated mordenite

The reaction pathway of benzene alkylation with propylene catalyzed by acids is very similar to that already reported for EB. The main difference is represented by the tendency of cumene to isomerize to n-propylbenzene, which is thermodynamically more stable at increased temperature. Also, cumene can undergo further alkylation to diisopropylbenzene (DIPB), which could be recovered by transalkylation with benzene to give cumene. The transalkylation reaction requires a higher temperature than the related alkylation. In addition, not all of the alkylation catalysts are suitable for transalkylation. Beta or dealuminated mordenite are suitable catalysts for transalkylation. The first industrial demonstrations of cumene technologies based on zeolite catalysts were started-up in 1996 by Mobil-Raytheon, EniChem and UOP, independently. In 2001, worldwide, 14 cumene units were already operating with zeolite catalysts. Around 98% ofcumene is used to produce phenol and expected world production of cumene in 2008 is around 9 million tons. For cumene, among the 40 units in the world (2004), 14 cumene plants were in operation with zeolite catalysts [222]. Today over 70% of cumene plants use a zeolite as the catalyst. 

Cumene synthesis Dealuminated mordenite MCM-22 beta Y omega Lower inputities Transalkylation function Lower benzene-to-propylene ratio allows higher capacity, great unit efficiency High selectivity Regenerable, non-hazardous, non-corrosive... 

DDM A process for making cumene from propylene and benzene by alkylation followed by transalkylation over a dealuminated mordenite catalyst. Operated since 1992 by Dow Chemicals at Terneuzen, the Netherlands. 

Since the development of zeolite, chemistry transalkylation has been studied mainly using zeolite catalysts. Frilette used natural mordenite treated by acid. The activity was much hi er than amorophous Si02 —AI2O3, but the activity could not be maintained. Benesi reported that mordenite was about 8 times more active than Y-type zeolites and that the active centers were Brensted acid sites. Various efforts including dealumination and cation exchange have been made to improve the aging. 

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