Jiang Chenggong, Chang Xin, Wang Xianhui, Zhao Zhi-Jian, Gong Jinlong
Key Laboratory for Green Chemical Technology of Ministry of Education, School of Chemical Engineering and Technology, Tianjin University Tianjin 300072 China
Collaborative Innovation Center of Chemical Science and Engineering Tianjin 300072 China.
Chem Sci. 2022 May 17;13(25):7468-7474. doi: 10.1039/d2sc01658c. eCollection 2022 Jun 29.
The lattice oxygen on transition metal oxides serves as a critical active site in the dehydrogenation of alkanes, whose activity is determined by electronic properties and environmental structures. Hydrogen affinity has been used as a universal descriptor to predict C-H bond activation, while the understanding of the environmental structure is ambiguous due to its complexity. This paper describes a combined theoretical and experimental study to reveal the activity of lattice oxygen species with different local structures, taking Mo-based oxides and C-H bond activation of low-carbon alkanes as model catalytic systems. Our theoretical work suggests that oxygen species with convex curvature are more active than those with concave curvature. Theoretically, we propose an interpretative descriptor, the activation deformation energy, to quantify the surface reconstruction induced by adsorbates with various environmental structures. Experimentally, a Mo-based polyoxometalate with the convex curvature structure shows nearly five times the initial activity than single-crystal molybdenum oxide with the concave one. This work provides theoretical guidance for designing metal oxide catalysts with high activity.
过渡金属氧化物上的晶格氧是烷烃脱氢反应中的关键活性位点，其活性由电子性质和环境结构决定。氢亲和性已被用作预测C-H键活化的通用描述符，而由于环境结构的复杂性，对其理解尚不明确。本文以钼基氧化物和低碳烷烃的C-H键活化为模型催化体系，开展了理论与实验相结合的研究，以揭示具有不同局部结构的晶格氧物种的活性。我们的理论研究表明，具有凸曲率的氧物种比具有凹曲率的氧物种更具活性。理论上，我们提出了一个解释性描述符——活化变形能，以量化由具有各种环境结构的吸附质引起的表面重构。实验上，具有凸曲率结构的钼基多金属氧酸盐的初始活性几乎是具有凹曲率的单晶氧化钼的五倍。这项工作为设计高活性金属氧化物催化剂提供了理论指导。
