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Evolution of Zn Species on Zn/HZSM‐5 Catalyst under H 2 Pretreated and its Effect on Ethylene Aromatization
Author(s) -
Gao Jie,
Wei Chunlei,
Dong Mei,
Wang Guofu,
Li Zhikai,
Qin Zhangfeng,
Wang Jianguo,
Fan Weibin
Publication year - 2019
Publication title -
chemcatchem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.497
H-Index - 106
eISSN - 1867-3899
pISSN - 1867-3880
DOI - 10.1002/cctc.201900596
Subject(s) - aromatization , ethylene , catalysis , extended x ray absorption fine structure , chemistry , selectivity , brønsted–lowry acid–base theory , zinc , zsm 5 , inorganic chemistry , density functional theory , absorption (acoustics) , xanes , nuclear chemistry , absorption spectroscopy , zeolite , organic chemistry , materials science , spectroscopy , computational chemistry , physics , quantum mechanics , composite material
Aromatization reaction is of importance in producing aromatics, accompanied by the generation of abundant H 2 , which may influence the reaction by interacting with the catalyst. In this work, Zn‐containing ZSM‐5 prepared by impregnation was treated in H 2 atmosphere at different temperatures, and the evolution in structure, acidity, and Zn species distribution were studied. The catalyst's performance in ethylene aromatization was also evaluated. The results show that the H 2 atmosphere enabled the reconstruction of ZnO microparticles and the reformation of Brønsted acid sites on Zn/HZSM‐5 below 200 °C. At an elevated temperature (300 °C), Zn + species were produced by the reduction of [ZnOZn] 2+ as confirmed by in‐situ Zn K ‐edge extended X‐ray absorption fine structure (EXAFS) study and density functional theory (DFT) calculation. After H 2 pretreatment at 300 °C, the increase in the amount of ZnOH + species increased the selectivity of Zn‐containing ZSM‐5 for aromatics from 62 % to 67 %.