Promoting Xylene Production in Benzene Methylation using Hierarchically Porous ZSM-5 Derived from a Modified Dry-gel Route

CATEGORY: XYLENE
Promoting Xylene Production in Benzene Methylation using Hierarchically Porous ZSM-5 Derived from a Modified Dry-gel Route

Type	Journal Article
Author	Wei Deng
Author	He Xuan
URL	http://www.sciencedirect.com/science/article/pii/S1004954114000330
Volume	22
Issue	8
Pages	921-929
Publication	Chinese Journal of Chemical Engineering
Date	August 2014
Abstract	While methylation of benzene is an alternative low-cost route to produce xylenes, selectivity to xylene remains low over conventional zeolitic catalysts. Researchers employed a combined dry-gel-conversion and steam-assisted-crystallization method to synthesize hierarchically porous zeolite ZSM-5 with varied Si/Al malar ratios. They found the method to be applicable to ZSM-5 with molar ratios of Si/Al from 20 to 180. They employed ZSM-5 zeolites as catalysts for benzene methylation at 460 °C to examine the effect of additional porosity and Si/Al ratios. At low Si/Al ratios, the benzene conversions over conventional and hierarchical ZSM-5 are close, and selectivity to toluene is high over hierarchical ZSM-5. Study results show that hierarchical porosity markedly enhances the utility of zeolite and the selectivity towards xylenes via improved mass transport at higher Si/Al ratios.