Transalkylation Properties of Hierarchical MFI and MOR Zeolites: Direct Synthesis over Modulating the Zeolite Grow Kinetics with Controlled Morphology

摘要

Hierarchical zeolites with improved diffusion rate are considered the best strategy to eliminate the limitation of purely microporous network in typical zeolite materials. Herein, hierarchical MFI (Hi-MFI) and hierarchical MOR (Hi-MOR) zeolites with controlled morphology were directly synthesized over modulating grow kinetics. The synthetic parameters were investigated systematically, including gel aging and crystallizing conditions. Using hexadecyl trimethyl ammonium bromide (CTAB) and tetrapropyl ammonium bromide (TPABr) as templates, Hi-MFI nanosheets and sphere-like zeolites were obtained. Besides, unilamellar, multilamellar, nanorod and worm-like Hi-MOR zeolites were synthesized in the presence of CTAB and polyethylene glycol (PEG). The transalkylation of toluene and 1,3,5-trimethylbenzene to xylene performance showed that the hierarchical structure of MFI and MOR zeolites enable zeolite with improved 1,3,5-trimethylbenzene conversion and xylene selectivity