Insights into the reaction mechanism of methanol-to-olefins conversion in HSAPO-34 from first principles: Are olefins themselves the dominating hydrocarbon pool species?
Insights into the reaction mechanism of methanol-to-olefins conversion in HSAPO-34 from first principles: Are olefins themselves the dominating hydrocarbon pool species?
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从第一原理洞察 HSAPO-34 中甲醇转化为烯烃的反应机理：烯烃本身是主要烃类吗？
DOI：
10.1016/j.jcat.2013.01.024
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发表时间：
2013-05
影响因子：
7.3
通讯作者：
Xie Zaiku
中科院分区：
文献类型：
--
作者：
Wang Chuanming;Wang Yangdong;Xie Zaiku
甲醇制烯烃（MTO）反应机理的全面理解是迫切需要的，尤其是对产品选择性的精确控制和沸石催化剂的合理设计。由于其复杂性，MTO反应机理至今仍是一个争议的热点领域。传统观点认为，MTO反应是通过烃藏机制进行的，甲苯类化合物是主要的烃藏组分。然而，通过广泛的周期密度泛函理论（DFT）计算在HSAPO-34催化剂，这项工作表明，烯烃本身以外的MB可能是占主导地位的烃池物种。建立了一个完整的反应网络，并制定了生产烯烃，烷烃和芳烃的路线。我们发现乙烯和丙烯等低碳烯烃主要是通过裂解前体（正碳离子、醇盐和高级烯烃）的裂解产生的，并且这些裂解前体是由较轻烯烃的甲基化形成的。从反应的角度来看，这些裂化前体在催化剂孔中的分布作为碳原子数影响产物选择性。随着裂解前体碳原子数的增加，裂解能垒有降低的趋势。两种烯烃之间的氢转移导致烷烃和二烯的形成，后者可能是形成芳烃的前体，随后导致催化剂失活。这个反应网络使我们能够合理化一些实验结果，更重要的是，提供了线索的选择性和失活的理解。
Full mechanistic understanding of methanol-to-olefins (MTO) conversion is urgently required, not least for the precise control of product selectivity and rational design of zeolite catalysts. Due to its complex nature, the MTO reaction mechanism is still a hot area of dispute. It was traditionally believed that the MTO reaction proceeds through hydrocarbon pool mechanism and methylbenzenes (MBs) are the predominant hydrocarbon pool species. However, by extensive periodic density functional theory (DFT) calculations in HSAPO-34 catalyst, this work indicates that olefins themselves other than MBs are likely to be the dominating hydrocarbon pool species. A full reaction network is established, and the routes to produce olefins, alkanes, and aromatics are formulated. We find that light olefins such as ethene and propene are mainly produced through the scission of cracking precursors (carbenium ions, alkoxides, and higher olefins), and which are formed by the methylation of lighter olefins. The distribution of these cracking precursors as the number of carbon atoms in the pore of catalysts influences the product selectivity from the reaction point of view. A decrease trend in the cracking energy barriers is observed with the carbon atom number of cracking precursors. Hydride transfer between two olefins results in the formation of alkanes and dienes and the latter are likely to be the precursors to form aromatics and subsequently leading to the deactivation of catalysts. This reaction network allows us to rationalize some experimental findings, and more importantly, provides clues on the understanding of selectivity and deactivation.
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影响因子：
7.3
作者：
Mei, Changsong;Wen, Pengyu;Gao, Zi
通讯作者：
Gao, Zi
影响因子：
3
作者：
Grimme, Stefan
通讯作者：
Grimme, Stefan
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
影响因子：
5.2
作者：
Wang Chuanming;Wang Yangdong;Liu Hongxing;Xie Zaiku;Liu Zhipan
通讯作者：
Liu Zhipan
影响因子：
12.9
作者：
Dai, Weili;Wang, Xin;Li, Landong
通讯作者：
Li, Landong
影响因子：
3.7
作者：
S. Svelle;U. Olsbye;A. Joensen;M. Bjørgen
通讯作者：
S. Svelle;U. Olsbye;A. Joensen;M. Bjørgen