A defect-based strategy for the preparation of mesoporous zeolite Y for high-performance catalytic cracking

Mesoporous ultra-stable Y zeolite with outstanding performance for heavy oil cracking was prepared through the combination of desilication and dealumination. Atomic removal of silicon atoms from the starting NaY zeolite framework during desilication was reported. Nucleation and propagation of mesopores in the following dealumination process was studied. Si(0Al) and Si(1Al) atoms are selectively removed from zeolite framework by desilication. Consequently, silanol nests and unique hydroxyl nests with framework associated Al-OH were created in the framework of the desilicated zeolite. The artificial defects effect the initiation of mesopores in crystal parts where used to be rich in framework silicon and unfavorable for mesopore formation and promote the propagation and coalescence of mesopores. Catalytic studies revealed improved activity and lifetime in the crack of 1,3,5-triisopropylbenzene and showed increased gasoline and light cycle oil selectivity when the conversion of a heavy oil was compared.

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► Desilication and dealumination are combined for Y zeolite ultra-stabilization.
► Framework defects are created by removal of framework silicon via desilication.
► Defects prompt nucleation and propagation of mesopores during dealumination.
► Mesoporosity of ultra-stable Y zeolite was upgraded without sacrificing aluminum.
► Increase in gasoline and light cycle oil yield was achieved.