Reaction Mechanism for Direct Cyclization of Linear C5, C6, and C7 Alkenes over H-ITQ-13 Zeolite Investigated Using Density Functional Theory
Reaction Mechanism for Direct Cyclization of Linear C5, C6, and C7 Alkenes over H-ITQ-13 Zeolite Investigated Using Density Functional Theory
复制标题
利用密度泛函理论研究线性 C-5、C-6 和 C-7 烯烃在 H-ITQ-13 沸石上直接环化的反应机理
DOI：
10.1002/cphc.201701020
复制
发表时间：
2018-02-19
期刊：
影响因子：
2.9
通讯作者：
Fan, Weibin
中科院分区：
文献类型：
--
作者：
Ma, Hong;Chen, Yanyan;Fan, Weibin
尽管二烯或三烯已被证明是可能的环化前体，但烯烃或醇盐的直接环化尚未得到系统研究。因此，本文通过考虑色散相互作用的密度泛函理论（DFT-D）研究了直链烯烃在 H-ITQ-13 上环化的反应机理。相同碳数的不同直链醇盐的相似自由能表明它们可以在甲醇制烯烃（MTO）过程中在673.15K的H-ITQ-13交叉点中共存。通过烯烃与甲氧基（ZOCH(3)）、三甲基氧鎓离子（TMO+）和甲醇甲基化形成直链烯烃在动力学上比通过烯烃二聚更有利。直链醇盐或烯烃比环烷烃更喜欢直接环化，而不是氢化物转移到二烯。该研究为MTO工艺中烯烃环化和芳构化机制提供了新的见解。
Although dienes or trienes have been shown to be possible precursors for cyclization, direct cyclization of alkenes or alkoxides has not been systematically studied yet. Thus, the reaction mechanism of cyclization of linear alkenes over H-ITQ-13 was investigated here by density functional theory considering dispersive interactions (DFT-D). The similar free energy of different linear alkoxides of the same carbon number suggests that they can co-exist in the H-ITQ-13 intersection at 673.15K during the methanol to olefins (MTO) process. The formation of linear alkenes by olefins methylation with methoxyl groups (ZOCH(3)), trimethyloxonium ions (TMO+), and methanol are kinetically more favorable than by dimerization of olefins. Linear alkoxides or alkenes prefer direct cyclization to cycloalkanes rather than hydride transfer to diene. This study provides new insight into the alkene cyclization and aromatization mechanisms in MTO process.