Stabilization of ZSM-5 zeolite catalysts for steam catalytic cracking of naphtha for production of propene and ethene

In order to increase ethene and propene, naphtha steam catalytic cracking has been considered. The cracking of C5–C12n-alkanes with ZSM-5 has been studied in absence and in presence of steam and the influence of the operation variables was studied. Irreversible catalyst deactivation by dealumination also occurs in the reactor when the cracking is carried out in the presence of steam. To diminish steam deactivation, the influence of zeolite Si/Al framework and a postsynthesis treatment by phosphorous have been studied and optimized. Much more stable catalyst can be achieved that result in an increase in activity without penalty for production of ethene and propene.

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► Dealumination of ZSM-5 zeolite occurs in steam catalytic cracking of naphtha.
► Si/Al ratio has a little influence on the rate of deactivation due to dealumination.
► Postsynthesis impregnation with phosphorous slow down the zeolite deactivation.
► Optimum amount of phosphorous depends on the Al content of zeolite.
► Introduction of phosphorous affects little the selectivities to ethene and propene.