Superior hydrocarbon catalytic performances of hierarchical porous molecular sieve were reported for reactions which were affected by diffusion limitation. Hierarchical porous ZSM-5 (denoted as ZSM-5B) was successfully prepared via steaming treatment of boron-containing ZSM-5. Boron was introduced into the framework of ZSM-5 in hydrothermal synthesis. The conventional ZSM-5 was treated by steaming as a contrast sample (denoted as ZSM-5C).N2 adsorption/desorption results showed a dimodal pore size distribution with mesopores of 4 nm and 8 nm for ZSM-5B while a pore size distribution with mesopores of only 4 nm for ZSM-5C. Meanwhile, the TEM micrographs revealed the existing of mesopores with an average pore diameter of 8 nm. It seems that the mesopores of 8 nm in ZSM-5B were introduced in the removal of framework Al and B atoms during steaming treatment. The N2 adsorption/desorption isotherm for ZSM-5B showed a remarkable larger hysteresis loop than that of ZSM-5C, indicative of extra mesopores. In the catalytic cracking of n-octane, ZSM-5B exhibited higher catalytic activity than ZSM-5C due to its special hierarchical porous structure. The activity of ZSM-5 catalyst was obviously enhanced by its hierarchical porous structure for hydrocarbon catalytic cracking.Key words:  ZSM-5; boron; steaming treatment; hierarchical porous

Hierarchical porestructure enhanced hydrocarbon catalytic cracking activity of ZSM-5 catalyst

248th National Meeting (2014)

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