Unraveling the influence of oxygen vacancies in MoOx catalysts on CO2 hydrogenation

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Vol. 495; p. 153333
• Main Authors: Jin, Fayi, Yang, Xiaoli, Yang, Jia, Lei, Yang, Xu, Wenfan, Jiang, Wei, Ma, Zhen, Liang, Gemeng, Ben, Haoxi, Li, Xingyun
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.09.2024
• Subjects: CO2; Molybdenum oxide; Oxygen vacancies; Reaction mechanism; Reverse water gas shift reaction; Reverse water gas shift reaction; Reaction mechanism; Molybdenum oxide; Oxygen vacancies; CO2
• ISSN: 1385-8947
• DOI: 10.1016/j.cej.2024.153333

Amounts of oxygen vacancies in MoOx was controllably orchestrated to exert a comprehensive influence on the CO2 hydrogenation reaction. [Display omitted] •The catalytic performance of MoOx catalysts exhibited a clear volcano-shaped trend, emphasizing the impact of oxygen vacancies on CO2 conversion and CO formation.•Steady-state kinetics revealed a significant enhancement in CO2 activation at optimal oxygen vacancy concentrations.•The catalytic reaction followed a formate pathway, with the hydrogenation of formate identified as the rate-determining step over MoOx catalysts. Oxygen vacancies in oxides are core parameters determining the catalytic performance in various reactions. This study investigated the influence of oxygen vacancies of MoOx catalysts on the reverse water gas shift (RWGS) reaction to gain a deep insight into the structure–function relationship. A distinct volcano-shaped trend was observed among MoOx catalysts with different amounts of oxygen vacancies. Through comprehensive characterizations and steady-state kinetic analysis, an optimal concentration of oxygen vacancies was identified to not only facilitate the adsorption and activation of CO2 but also restrain the formation of by-product CH4. In-situ characterizations combined with DFT calculations uncovered a formate-involved reaction pathway over the oxygen vacancies structured MoOx catalyst, with the hydrogenation of formate identified as the rate-determining step. These findings not only showcase the potential of Mo-based oxides in CO2 hydrogenation reactions but also provide fundamental insights into the role of oxygen vacancies in shaping catalytic behavior.