Direct synthesis of acetic acid from carbon dioxide and methane over Cu-modulated BEA, MFI, MOR and TON zeolites: a density functional theory study
Direct synthesis of acetic acid from carbon dioxide and methane over Cu-modulated BEA, MFI, MOR and TON zeolites: a density functional theory study
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在 Cu 调制的 BEA、MFI、MOR 和 TON 沸石上由二氧化碳和甲烷直接合成乙酸：密度泛函理论研究
DOI：
10.1039/c9cy01803d
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发表时间：
2019
影响因子：
5
通讯作者：
Wang Jianguo
中科院分区：
文献类型：
--
作者：
Wang Sen;Guo Shujia;Luo Yaoya;Qin Zhangfeng;Chen Yanyan;Dong Mei;Li Junfen;Fan Weibin;Wang Jianguo
由二氧化碳和甲烷直接合成醋酸被认为是一种绿色和原子经济的过程，它可以合理地利用两种主要造成温室效应的气体，但由于甲烷和二氧化碳的化学惰性，该过程面临着寻找有效催化剂的巨大挑战。本文用周期密度泛函理论(DFT)方法研究了铜修饰的BEA、MFI、MOR和TON分子筛上二氧化碳和甲烷催化转化为乙酸的反应，包括CH4的吸附、C-H键的解离、C-C键的偶联、醋酸酯的质子化和醋酸的脱附。结果表明，铜调变沸石的催化活性与活性铜物种的结构和沸石孔道结构密切相关。与单核铜([Cu]2+)相比，三维BEA和MFI分子筛中的双核铜氧簇([CuOCu2+)和一维MoR和TON分子筛中的三核铜氧簇([Cu3(μ-O)3]2+)对二氧化碳和甲烷直接转化为乙酸具有催化活性。特别是，负载有[Cu3(μ-O)3]2+团簇的MoR分子筛([Cu3(μ-O)3]-MoR)具有较低的表观活化能(57kJ−1)，具有较高的催化活性。本文的研究成果将有助于阐明铜系分子筛的催化作用以及二氧化碳和甲烷合成醋酸的反应机理，为设计高效的二氧化碳和甲烷转化催化剂提供一些线索。
Direct synthesis of acetic acid from carbon dioxide and methane is considered a green and atom-economic process, which can rationally utilize two gases contributing mostly to the greenhouse effect; however, this process faces a tremendous challenge of finding an efficient catalyst due to the chemical inertness of methane and carbon dioxide. Herein, the catalytic conversion of carbon dioxide and methane to acetic acid over Cu-modulated BEA, MFI, MOR and TON zeolites, including the adsorption of CH4, dissociation of C–H bonds, C–C bond coupling, protonation of acetate, and desorption of acetic acid, was investigated by using the periodic density functional theory (DFT) calculation. The results indicate that the catalytic activity of Cu-modulated zeolites is closely related to the structure of both active copper species and zeolite pore channels. The binuclear copper-oxo cluster ([CuOCu]2+) in the three-dimensional BEA and MFI zeolites and trinuclear copper-oxo cluster ([Cu3(μ-O)3]2+) in the one-dimensional MOR and TON zeolites are catalytically active in the direct conversion of carbon dioxide and methane to acetic acid, in comparison with the mononuclear copper ([Cu]2+) species. In particular, the MOR zeolite carrying [Cu3(μ-O)3]2+ clusters ([Cu3(μ-O)3]-MOR) exhibits superior catalytic activity in the production of acetic acid with a low apparent activation energy (57 kJ mol−1). The insights shown in this work should be helpful in clarifying the catalysis of Cu-modulated zeolites and the reaction mechanism of producing acetic acid from carbon dioxide and methane, which can provide some clues for the design of efficient catalysts in the conversion of carbon dioxide and methane.