文献类型：会议论文

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

作者：Deng, Wei[1];He, Xuan[1];Zhang, Chao[1];Gao, Yunyi[1];Zhu, Xuedong[1];Zhu, Kake[1];Huo, Qisheng[2];Zhou, Zhijie[3]

机构：[1]E China Univ Sci & Technol, Coll Chem Engn, Shanghai 200237, Peoples R China;[2]Jilin Univ, Coll Chem, State Key Lab Inorgan Synth & Preparat Chem, Changchun 130012, Peoples R China;[3]E China Univ Sci & Technol, Minist Educ, Key Lab Coal Gasificat, Shanghai 200237, Peoples R China

会议论文集：International conference on structured catalysts and reactions

会议日期：SEP 25-27, 2013

会议地点：Beijing, PEOPLES R CHINA

语种：英文

外文关键词：Hierarchical zeolite; Benzene; Methanol; Methylation; ZSM-5; Process intensification

摘要：Methylation of benzene is an alternative low-cost route to produce xylenes, but selectivity to xylene remains low over conventional zeolitic catalysts. In this work, a combined dry-gel-conversion and steam-assisted-crystallization method is used to synthesize hierarchically porous zeolite ZSM-5 with varied Si/Al malar ratios. X-ray diffraction (XRD), N-2 physisorption, NH3-temperature programmed desorption (TPD), scanning electronic microscopic (SEM) measurement and Fourier transforminfrared (FT-IR) are employed to characterize the structure and acidity of both hierarchically porous zeolites and their conventional counterparts. The method is found to be applicable to ZSM-5 with molar ratios of Si/Al from 20 to 180. The ZSM-5 zeolites are used as catalysts for benzene methylation at 460 degrees C to investigate 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. It is found that hierarchical porosity markedly enhances the utility of zeolite and the selectivity towards xylenes via improved mass transport at higher Si/Al ratios. Under an optimized hierarchical ZSM-5 catalyst, xylene selectivity reaches 34.9% at a Si/Al ratio of 180. (C) 2014 The Chemical Industry and Engineering Society of China, and Chemical Industry Press. All rights reserved.