Center for Petroleum, Petrochemicals, and Advanced Materials and Department of Chemistry, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand.
Phys Chem Chem Phys. 2012 Dec 28;14(48):16588-94. doi: 10.1039/c2cp42066j. Epub 2012 Aug 20.
The direct conversion of methane and carbon dioxide to acetic acid is one of the most challenging research topics. Using the density functional theory (M06-L) the study reveals the catalytic activity of the Au(I)-ZSM-5 zeolite in this reaction. The Au(I)-ZSM-5 is represented by a 34T quantum cluster model. The activation of the C-H bond over the Au-ZSM-5 zeolite would readily take place via the homolytic σ-bond activation with an energy barrier of 10.5 kcal mol(-1), and subsequent proton transfer from the Au cation to the zeolitic oxygen, yielding the stable methyl-gold complex adsorbed on the zeolite Brønsted acid. The conversion of CO(2) on this bi-functional catalyst involves the Brønsted acid site playing a role in the protonation of CO(2) and the methyl-gold complex acting as a methylating agent. The activation energy of 52.9 kcal mol(-1) is predicted.
甲烷和二氧化碳直接转化为乙酸是最具挑战性的研究课题之一。本研究采用密度泛函理论（M06-L）揭示了 Au(I)-ZSM-5 沸石在该反应中的催化活性。Au(I)-ZSM-5 采用 34T 量子团簇模型表示。在 Au-ZSM-5 沸石上，C-H 键的活化很容易通过均裂 σ 键活化进行，其能垒为 10.5 kcal/mol，随后 Au 阳离子向沸石氧转移质子，生成稳定的吸附在沸石 Brønsted 酸上的甲基金络合物。在这种双功能催化剂上 CO(2)的转化涉及 Brønsted 酸位在 CO(2)质子化中的作用，以及甲基金络合物作为甲基化剂的作用。预测其活化能为 52.9 kcal/mol。
