Pore Selectivity for Olefin Protonation Reactions Confined inside Mordenite Zeolite: A Theoretical Calculation Study
Pore Selectivity for Olefin Protonation Reactions Confined inside Mordenite Zeolite: A Theoretical Calculation Study
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DOI：
10.1021/jp311264u
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发表时间：
2013-01
影响因子：
3.7
通讯作者：
Yueying Chu;B. Han;Anmin Zheng;Xianfeng Yi;F. Deng
中科院分区：
文献类型：
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作者：
Yueying Chu;B. Han;Anmin Zheng;Xianfeng Yi;F. Deng
用B3LYP+D/6-31G(D，P)//ONIOM(B3LYP/6-31G(D，P)：MNDO)方法研究了丝光沸石不同孔结构(12-MR和8-MR通道)中质子化烯烃的活性，揭示了质子化反应的孔选择性。结果表明，与分子筛孔(12-MR和8-MR通道)相比，乙烯的分子尺寸较小，孔限制作用较弱，固体酸的本征酸强度对反应起关键作用，导致乙烯质子化优先发生在12-MR通道内的强酸中心。对于丙烯，由于反应物与MoR沸石的8-MR通道匹配良好，反应可以在两个通道(12-MR和8-MR)内进行。在这种情况下，稳定中间体和过渡态的限制效应补偿了8-MR通道中酸性中心的不足。然而，对于体积较大的异丁烯，会发生质子化反应。
The activity of olefins protonated by Bronsted acid sties in different pore structures (12-MR and 8-MR channel) of mordenite (MOR) zeolite is investigated by the B3LYP+D/6-31G(D,P)//ONIOM(B3LYP/6-31G(D,P):MNDO) method to reveal the pore selectivity for the protonation reaction. It is demonstrated that for ethene, the size of the molecule is smaller compared with the zeolite pores (both 12-MR and 8-MR channels), the pore confinement effect is weak, and the intrinsic acid strength of the solid acid plays a key role in the reaction, resulting in that the ethene protonation occurs preferentially at the strong acid sites within the 12-MR channel. For propene, the reaction can occur inside both channels (12-MR and 8-MR) due to the reactant being well fitted into the 8-MR channel of MOR zeolite. In this case, the confinement effect that stabilizes the intermediates and transition states compensates the deficiency of acid sites in the 8-MR channel. However, for the bulky isobutene, the protonation reaction occurs...