Metal-Na2WO4/SiO2催化甲烷氧化偶联的密度泛函理论研究

低碳烷烃直接转化成高附加值化工产品是当今催化领域的研究热点，甲烷氧化偶联催化转化制C2烃被认为是最具挑战性的课题之一。众多催化剂中，Mn/Na2WO4/SiO2催化剂是最具有工业化前景催化剂之一。但金属助剂与Na2WO4配位方式对构效关系的影响没有系统深入的研究，且活性氧种类仍然存在争议。本项目以密度泛函理论为基础，拟构建多种金属助剂匹配Na2WO4氧化物的方式，包括原子掺杂或负载、团簇或晶相氧化物负载等；拟探究Na2WO4不同晶面和助剂匹配方式对不同类型氧物种{O2-、O-、O(2)-、O(2)2-}之间的动态平衡转化的影响；拟利用微观动力学模拟高温反应气氛，揭示原位反应条件下不同活性位结合不同氧物种活化甲烷C-H键能力，在分子/原子层面筛选可能的活性位点、活性晶面和最佳亲电氧物种，为工业催化剂的开发提供理论指导。

The direct conversion of low carbon alkanes into high value-added chemical products is a hot spot in the field of catalysis，including the Oxidative Coupling of Methane (OCM) reaction forming C2 hydrocarbons, which has been considered as one of the most challenging subjects. Among the catalysts for OCM, the Mn/Na2WO4/SiO2 catalyst is one of the most promising catalysts for industrialization. However, the effect of coordination mode of metal additives and Na2WO4 on structure-activity relationship has not been studied systematically and deeply, and the speciation of active oxygen is still controversial. Based on the density functional theory, this project will build a variety of matching method between metal additives and Na2WO4, including the doping of single/multiple atom(s) and the supporting of the atom/clusters/crystal oxide. The influence of different exposing crystal planes of Na2WO4 and the matching mode of the additives on dynamic equilibrium transformation between different oxygen species {O2-、O-、O(2)-、O(2)2-} will be calculated. By using micro dynamics simulation of high temperature reaction atmosphere, the ability of different active sites combined with different oxygen species to activate C-H bond of methane under reaction conditions will be revealed. The possible active sites, active crystal planes and the best electrophilic oxygen species will be screened at the molecular/atomic level to provide theoretical guidance for the development of industrial catalysts.