Elucidating the olefin formation mechanism in the methanol to olefin reaction over AlPO-18 and SAPO-18

被引：76

作者：

Chen, Jingrun ^{[1
,2
]}

Li, Jinzhe ^{[1
]}

Yuan, Cuiyu ^{[1
]}

Xu, Shutao ^{[1
]}

Wei, Yingxu ^{[1
]}

Wang, Quanyi ^{[1
,2
]}

Zhou, You ^{[1
,2
]}

Wang, Jinbang ^{[1
,2
]}

Zhang, Mozhi ^{[1
,2
]}

He, Yanli ^{[1
]}

Xu, Shuliang ^{[1
]}

Liu, Zhongmin ^{[1
]}

机构：

[1] Chinese Acad Sci, Dalian Inst Chem Phys, Dalian Natl Lab Clean Energy, Natl Engn Lab Methanol Olefins, Dalian 116023, Peoples R China

[2] Univ Chinese Acad Sci, Beijing 100049, Peoples R China

来源：

CATALYSIS SCIENCE & TECHNOLOGY | 2014年 / 4卷 / 09期

基金：

中国国家自然科学基金;

关键词：

BRONSTED ACID SITES; TO-HYDROCARBONS; CATALYTIC CYCLE; CARBENIUM IONS; HEPTAMETHYLBENZENIUM CATION; ZEOLITE H-ZSM-5; COKE FORMATION; CONVERSION; DEACTIVATION; SELECTIVITY;

D O I：

10.1039/c4cy00551a

中图分类号：

O64 [物理化学（理论化学）、化学物理学];

学科分类号：

070304 ; 081704 ;

摘要：

The mechanism of the methanol to olefin (MTO) reaction over AlPO-18 (without Bronsted acid sites) and two SAPO-18 (with different Bronsted acid site densities) catalysts has been investigated. The Bronsted acid site density of AlPO-18 and SAPO-18 catalysts was determined by H-1 MAS NMR spectroscopy. Methanol conversion over the catalysts showed that the catalytic activity of the catalysts was strongly influenced by their Bronsted acid site density. Using C-13 magic angle spinning (MAS) NMR, we directly observed the pentamethylcyclopentenyl cation (pentaMCP(+)) over SAPO-18 under real MTO reaction conditions, but no carbenium ion was detected over AlPO-18. Furthermore, analysis of confined organics by C-13 MAS NMR and GC-MS clearly demonstrated that higher Bronsted acid site density improved the formation and accumulation of some important and reactive hydrocarbon pool species, such as pentaMCP(+) and polymethylbenzenes. With the aid of the C-12/C-13-methanol switch technique, the detailed olefin formation mechanism was elucidated. During the MTO reaction, light olefin generation over SAPO-18 mainly followed the aromatic-based hydrocarbon pool mechanism; however, the olefin methylation and cracking mechanism accounted for the production of light olefins over AlPO-18.

引用

页码：3268 / 3277

页数：10

共 54 条

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