The influence of pore structure on reaction mechanism of propylene dimerization in zeolite: A theoretical viewpoint
The influence of pore structure on reaction mechanism of propylene dimerization in zeolite: A theoretical viewpoint
复制标题
孔结构对沸石丙烯二聚反应机理的影响：理论观点
DOI：
10.1002/qua.25962
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发表时间：
2019
影响因子：
2.2
通讯作者：
Shen Wanling
中科院分区：
文献类型：
--
作者：
Li Xin;Shen Wanling
分子筛作为环境友好型催化剂已广泛应用于石油化工行业。沸石的孔结构是影响其催化性能的重要因素。本文采用N层积分分子轨道和分子力学相结合的方法，研究了丙烯在四种不同孔结构的分子筛（ZSM-5，MCM-22，MCM-22和莫尔）中的二聚反应机理。比较分步机理和协同机理，发现在大孔沸石、MCM-22和莫尔分子筛中，分步机理和协同机理相互竞争，两种机理都是可能的。然而，在具有中等孔径的ZSM-5沸石中，丙烯二聚反应倾向于根据分步机理进行。此外，无论采用哪种机理，MCM-22中丙烯二聚反应的活化能在四种沸石中最小，表明其MWW-型结构（国际沸石协会定义的一种骨架类型）可能是反应最有利的孔结构，具有最高的催化活性。
Molecular sieves have been widely used in the petrochemical industry as environment‐friendly catalysts. The pore structure is an important factor influencing the catalytic performance of the zeolite. In this work, a combined Our own N‐layered Integrated molecular Orbital and Molecular mechanics method was used to study the mechanism of propylene dimerization in four zeolites (ZSM‐5, BEA, MCM‐22, and MOR) with different pore structures. Comparing the stepwise mechanism and the concerted mechanism, it is found that the two mechanisms compete with each other in the macroporous BEA, MCM‐22, and MOR zeolites, and both mechanisms are possible. However, in ZSM‐5 zeolite with medium pore size, the propylene dimerization reaction tends to proceed according to the stepwise mechanism. Furthermore, no matter which mechanism is adopted, the activation energy of propylene dimerization reaction in MCM‐22 is the smallest in the four zeolites, indicating that its MWW‐type structure (A framework type defined by the International Zeolite Association) may be the most favorable pore structure for the reaction and possesses the highest catalytic activity.