文献类型：期刊文献

英文题名：Elucidating the methanol conversion in H-SAPO-5 from first principles: Nature of hydrocarbon pool and scission style

作者：Zhang, Shuai-Hui[1,2];Wang, Chuan-Ming[1];Zhou, Xing-Gui[2];Zhu, Yi-An[2]

机构：[1]SINOPEC, Shanghai Res Inst Petrochem Technol, State Key Lab Green Chem Engn & Ind Catalysis, Shanghai 201208, Peoples R China;[2]East China Univ Sci & Technol, Sch Chem Engn, United Chem React Engn Res Inst UNILAB, State Key Lab Chem Engn, Shanghai 200237, Peoples R China

年份：2020

卷号：490

外文期刊名：MOLECULAR CATALYSIS

收录：;EI(收录号：20202108691985);WOS:【SCI-EXPANDED(收录号:WOS:000541664600006)】；

基金：This work was financially supported by the National Natural Science Foundation of China (Grant No. 21673295, 21473053, and 91645122), the National Key Research and Development Program of China (Grant No. 2016YFB0701100, 2017YFB0702800, and 2018YFB0604700), and the Fundamental Research Funds for the Central Universities (Grant No. 222201718003).

语种：英文

外文关键词：H-SAPO-5; Methanol conversion; Hydrocarbon pool mechanism; Zeolite catalysis; Density functional theory

摘要：Silicoaluminophosphate (SAPO)-based zeolites have been demonstrated to be the potential active catalysts for the methanol conversion to produce hydrocarbons like light olefins. However the underlying reaction mechanism is yet to be fully understood. In this work, periodic density functional theory calculations were performed to address the hydrocarbon pool (HP) mechanism involving both aromatics and olefins as the hydrocarbon pool species in H-SAPO-5. We demonstrated that the olefins themselves rather than aromatics are likely to be the dominating HP species in H-SAPO-5. In the case of the olefin-based HP pathway, we proposed three different scission styles of cracking precursors to produce olefins, namely, concerted cracking with water, concerted cracking without water, and stepwise cracking without water. It was found that propene and butenes rather than ethene are the dominant products via the cracking of higher cracking precursors, like higher olefins and carbenium ions. The energy barriers of the olefin-based pathway are lower than 160 kJ/mol at 673 K, much lower than those in the aromatic-based pathway. The established linear scaling relations between the transition state energies and the number of carbon atoms in olefin-based cycle reveal that the van der Waals stabilization dominates the interaction between framework and organic moiety for olefin methylation and cracking in H-SAPO-5. This theoretical work further highlights the importance of olefin-based cycle and provides some implications to understand product distribution via different cracking style in zeolite catalyzed methanol conversion.