Modeling C–H Bond Activation and Oxidations of Alkanes over Cu–MOR Using First-Principles Methods
Modeling C–H Bond Activation and Oxidations of Alkanes over Cu–MOR Using First-Principles Methods
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使用第一性原理方法对 Cu-MOR 上的 C-H 键活化和烷烃氧化进行建模
DOI：
10.1021/acs.jpcc.9b00194
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发表时间：
2019
期刊：
影响因子：
--
通讯作者：
Liu, Bin
中科院分区：
文献类型：
--
作者：
Xu, Jiayi;Liu, Bin
甲烷直接转化为甲醇可以显著提高页岩气利用的经济价值。然而，稳定的C-H键使甲烷部分氧化成为一个具有挑战性的催化任务。在低温下，C-H键活化是动力学缓慢的。另一方面，甲烷可能在高温下完全氧化成CO2，这将降低甲醇选择性。固定在丝光沸石（莫尔）骨架中的几种Cu-氧代络合物如单（μ-氧代）二铜、双（μ-氧代）二铜和三氧代铜显示出平衡甲烷至甲醇转化的催化活性和产物选择性。在密度泛函理论（DFT）框架下，利用BEEF-vdW泛函对Cu-氧代配合物作为C-H键活化中心的热力学稳定性进行了研究，确定了双（μ-氧代）二铜结构是最稳定的构型.然后用轻质烃的第一个C-H键的活化测试这些络合物的催化反应性（即，甲烷、乙烷和丙烷），以及随后氧化成相应醇的步骤。具有最高自旋密度的Cu-trioxo簇的位点II仍然是最有效的活性位点，当考虑电子自旋交叉时，其使初始甲烷活化的能垒最低。第一C-H活化步骤的能垒遵循甲烷、乙烷和丙烷的降序。
Direct conversion of methane to methanol can significantly boost the economic value of shale gas utilization. However, the stable C–H bond makes methane partial oxidation a challenging catalysis task. At low temperatures, C–H bond activation is kinetically sluggish. On the other hand, methane is likely oxidized fully into CO2at high temperatures, which will lower methanol selectivity. Several Cu–oxo complexes such as mono(μ-oxo)dicopper, bis(μ-oxo)dicopper, and copper trioxo anchored in the mordenite (MOR) zeolite framework are shown to balance catalytic activity and product selectivity for the methane-to-methanol conversion. In this work, the thermodynamic stability of Cu–oxo complexes was evaluated as active centers for C–H bond activation using the BEEF-vdW functional within the density functional theory (DFT) framework, and the bis(μ-oxo)dicopper moiety was identified as the most stable configuration. The catalytic reactivity of these complexes was then tested with the activation of the first C–H bond of light hydrocarbons (i.e., methane, ethane, and propane), as well as subsequent oxidation steps to corresponding alcohols. Site II of the Cu–trioxo cluster with highest spin density remains as the most potent active site by enabling the lowest energy barrier for initial methane activation when electronic spin crossing was considered. Energy barriers for the first C–H activation step follow a decreasing order of methane, ethane, and propane.
影响因子：
5.5
作者：
Liakos, Dimitrios G.;Neese, Frank
通讯作者：
Neese, Frank
影响因子：
12.9
作者：
Dinh, Kimberly T.;Sullivan, Mark M.;Roman-Leshkov, Yuriy
通讯作者：
Roman-Leshkov, Yuriy
Rietveld 改进了几种丝光沸石结构模型，解释了 X 射线粉末图案的差异
DOI：
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发表时间：
1994
期刊：
影响因子：
--
作者：
P. Rudolf;J. Garcés
通讯作者：
J. Garcés