Chemoselectivity during propene hydrogenation reaction over H-ZSM-5 zeolite: Insights from theoretical calculations
Chemoselectivity during propene hydrogenation reaction over H-ZSM-5 zeolite: Insights from theoretical calculations
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DOI：
10.1016/j.micromeso.2009.01.026
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发表时间：
2009-05
影响因子：
5.2
通讯作者：
Anmin Zheng;Shang-Bin Liu;F. Deng
中科院分区：
文献类型：
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作者：
Anmin Zheng;Shang-Bin Liu;F. Deng
采用基于扩展的64 T原子簇模型的密度泛函方法，对H-ZSM-5分子筛上丙烯加氢反应的产物选择性和详细的反应途径进行了研究。相应地，结构参数和活化势垒高度以及反应能量可以从优化的吸附复合物中推导出来。通过与基于简化的8 T团簇模型预测的结果进行比较，表明沸石骨架引起的长程静电效应有效地稳定了碳正离子过渡态。考察了丙氧基配合物的稳定性和酸强度对反应机理的影响。发现丙烯加氢反应是严格的动力学控制，异丙醇盐的形成本质上比正丙醇盐在沸石上更有利，特别是那些具有较高酸强度的沸石。
A comprehensive study has been made on product selectivity and detailed reaction pathway invoked during propene hydrogenation reaction over H-ZSM-5 zeolite by DFT calculations based on an extended 64T cluster model. Accordingly, structural parameters and activation barrier heights as well as reaction energies can be deduced from the optimized adsorption complexes. By comparing with the results predicted based on simplified 8T cluster models, it is indicative that the carbonium ion transition states are effectively stabilized by the long-range electrostatic effects provoked by the zeolite framework. The stability of the propoxide complexes and the effects of acid strength on reaction mechanism were also investigated. It is found that the propene hydrogenation reaction is strictly kinetically controlled and the formation of i-propoxide is intrinsically much more favorable than n-propoxide over zeolites, particularly those with higher acidic strengths.