Multiple impregnation technique for the preparation of ex situ selectivated zeolite catalysts

Abstract

A ex situ selectivated catalytic molecular sieve for enhanced shape selective hydrocarbon conversions in which a catalytic molecular sieve is modified by being exposed to at least two selectivation sequences, each sequence including an impregnation of the molecular sieve with a selectivating agent and a subsequent calcination of the impregnated molecular sieve. The ex situ selectivation method is also described, including the use of aqueous carriers for the selecting agent. Also a method for in situ trim-selectivating the modified catalytic molecular sieve. Also, a method for moderate steaming of the selectivated molecular sieve. Also a method for in situ trim-selectivating the modified catalytic molecular sieve. Also described is the process for shape selective hydrocarbon conversion comprising contacting a hydrocarbon feedstream under conversion conditions with the selectivated molecular sieve.

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