Theoretical insight into the minor role of paring mechanism in the methanol-to-olefins conversion within HSAPO-34 catalyst
Theoretical insight into the minor role of paring mechanism in the methanol-to-olefins conversion within HSAPO-34 catalyst
复制标题
HSAPO-34 催化剂内配对机制在甲醇转化为烯烃中的次要作用的理论见解
DOI：
10.1016/j.micromeso.2012.04.004
复制
发表时间：
2012-08
影响因子：
5.2
通讯作者：
Liu Zhipan
中科院分区：
文献类型：
--
作者：
Wang Chuanming;Wang Yangdong;Liu Hongxing;Xie Zaiku;Liu Zhipan
在甲醇制烯烃(MTO)反应中，迫切需要深入了解油气藏物种的结构及其对催化活性和选择性的影响。根本问题是对其反应机理的理解。在此之前，我们已经阐明了一个完整的催化循环侧链油气成藏机理。本文采用周期密度泛函理论计算方法，对HSAPO-34分子筛催化剂中不同甲基苯(MBS)的缩合成藏机理进行了综合研究。完整的催化循环包括一系列基本步骤，包括甲基化、环收缩、质子或甲基的移动、侧烷基团的消除和MBS的再生。主要的瓶颈被认为是从五元环阳离子再生MBS。具有五元环结构的中间阳离子和具有初级碳正离子特征的过渡态在配对过程中不稳定。不同MBS的总能垒强烈依赖于甲基基团的数量。通过比较修剪路径和侧链路径的动力学，我们证明了完全修剪机制具有较高的势垒，在MTO转化过程中是一条次要的路径。
Insight into the structure of hydrocarbon pool species and its effect on the catalytic activity and selectivity are urgently required in methanol-to-olefins (MTO) conversion. The fundamental issue is the understanding of its reaction mechanism. Previously, we have elucidated a complete catalytic cycle of side chain hydrocarbon pool mechanism. In this paper, paring hydrocarbon pool mechanism for different methylbenzenes (MBs) in HSAPO-34 zeotype catalyst is comprehensively investigated by periodic density functional theory calculations. The complete catalytic cycle involves a sequence of elementary steps that include methylation, ring contraction, shift of proton or methyl group, elimination of side alkyl groups, and regeneration of MBs. The major bottleneck is identified as the regeneration of MBs from five-membered ring cations. The intermediate cations having five-membered ring structure and the transition states featuring primary carbocations are unstable in the paring route. The overall energy barriers of different MBs depend strongly on the number of methyl groups. By comparing the kinetics of the paring route and the side chain route, we demonstrate that the full paring mechanism exhibits a higher barrier, and which is a minor route in the MTO conversion.
登录
查看更多内容
影响因子：
3
作者：
Grimme, Stefan
通讯作者：
Grimme, Stefan
影响因子：
16.5
作者：
Yangdong Wang;Chuanming Wang;Hongxing Liu;Zaiku Xie
通讯作者：
Yangdong Wang;Chuanming Wang;Hongxing Liu;Zaiku Xie
影响因子：
12.9
作者：
Dai, Weili;Wang, Xin;Li, Landong
通讯作者：
Li, Landong
DOI：
10.1021/jp058166f
发表时间：
2005-10
期刊：
The journal of physical chemistry. A
影响因子：
--
作者：
B. Arstad;S. Kolboe;O. Swang
通讯作者：
B. Arstad;S. Kolboe;O. Swang
影响因子：
3.7
作者：
Qingjun Zhu;J. Kondo;T. Tatsumi;S. Inagaki;Ryosuke Ohnuma;Y. Kubota;Y. Shimodaira;Hisayoshi Kobayashi;K. Domen
通讯作者：
Qingjun Zhu;J. Kondo;T. Tatsumi;S. Inagaki;Ryosuke Ohnuma;Y. Kubota;Y. Shimodaira;Hisayoshi Kobayashi;K. Domen