Luo Dehui, Luo Ran, Wang Xianhui, Chang Xin, Yang Tingting, Chen Sai, Zhao Zhi-Jian, Gong Jinlong
School of Chemical Engineering & Technology, Key Laboratory for Green Chemical Technology of Ministry of Education, Tianjin University, Collaborative Innovation Center for Chemical Science & Engineering (Tianjin) Tianjin 300072 China
Joint School of National University of Singapore and Tianjin University, International Campus of Tianjin University Binhai New City Fuzhou 350207 Fujian China.
Chem Sci. 2025 Jan 22;16(11):4710-4717. doi: 10.1039/d4sc07811j. eCollection 2025 Mar 12.
Redox catalysts play a critical role in chemical looping oxidative dehydrogenation of propane (CL-ODH). However, challenges persist in modulating lattice oxygen in metal oxides and maintaining surface oxygen coverage to prolong the oxidative dehydrogenation stage. This paper describes the role of oxygen vacancies by evaluating numerous vacancy distribution patterns, including surface and bulk distributions, to identify VO surfaces across a wide range of reduction degrees, guided by calculated oxygen vacancy formation energy. The surface reactions are classified into three distinct stages based on surface oxygen vacancy coverage (Ovc), with transitions between stages attributed to the excessive reactivity of lattice oxygen, variations in vanadium valence states, and the localized limitations of vacancy effects. Additionally, four high-valent metal dopants (W, Mo, Nb, and Os) identified through charge transfer energy (CTE)-based descriptors effectively reduce oxygen reactivity while optimizing the utilization of bulk lattice oxygen to maintain favorable surface Ovc. These findings provide essential theoretical insights and a strategic framework for the rational design of redox catalysts in CL-ODH applications.
氧化还原催化剂在丙烷化学链氧化脱氢（CL-ODH）中起着关键作用。然而，在调节金属氧化物中的晶格氧以及维持表面氧覆盖率以延长氧化脱氢阶段方面，挑战依然存在。本文通过评估多种空位分布模式，包括表面和体相分布，来描述氧空位的作用，以在计算出的氧空位形成能的指导下，识别不同还原度范围内的VO表面。基于表面氧空位覆盖率（Ovc），表面反应被分为三个不同阶段，阶段之间的转变归因于晶格氧的过度反应性、钒价态的变化以及空位效应的局部局限性。此外，通过基于电荷转移能（CTE）的描述符确定的四种高价金属掺杂剂（W、Mo、Nb和Os）有效地降低了氧反应性，同时优化了体相晶格氧的利用，以维持良好的表面Ovc。这些发现为CL-ODH应用中氧化还原催化剂的合理设计提供了重要的理论见解和战略框架。
