Surface oxygen vacancy regulation and active metal doping for Cu-Al based spinel catalysts synthesis toward high-efficiency reverse water-gas shift reaction

• Published in: Catalysis today 2025-01, Vol.443, p.114968, Article 114968
• Main Authors: Ye, Zhiheng, Zhao, Jijing, Zheng, Jiayi, Xu, Ziyi, Hu, Hongyu, Li, Wenhan, Hu, Zhong-Ting, Wang, Junliang, Pan, Zhiyan, Hu, Mian
• Format: Article
• Language: English
• Subjects: Active metal doping; CO selectivity; Cu-Al based spinel catalyst; Reverse water-gas shift reaction; Surface oxygen vacancy regulation
• ISSN: 0920-5861
• DOI: 10.1016/j.cattod.2024.114968

The reverse water-gas shift (RWGS) reaction is of great significance to convert CO2 to valuable feedstocks. Reasonable design and preparation of catalysts is necessary to achieve high CO2 conversion and CO selectivity. In this study, a series of Cu-Al based spinel catalysts were synthesized by coprecipitation-calcination method or A-site doped with active metal (Co, Zn, Mg, and Fe) for the RWGS reaction. The results indicated that the surface oxygen vacancies and crystal structure of CuAl2O4 can be regulated by calcination temperature. Remarkably, the CuAl-800 catalyst exhibits the highest CO2 conversion rate (62.7 %) with 100 % CO selectivity at 500 °C. Excessive calcination temperatures (> 800 °C) resulted in a well-defined spinel structure, but decreased surface oxygen vacancies and CO2 conversion rate. At calcination temperatures < 800 °C, surface oxygen vacancies increased, but the formation of CuO impurities which irreversibly converted to Cu2O during reduction, decreased catalytic activity. Compared with Zn, Mg and Fe, Co doping can significantly improved the reactivity of CuAl2O4 catalyst in RWGS reaction at 500 °C, increasing the CO2 conversion rate by 8 % while maintaining 100 % CO selectivity. The main reason is that Co doping not only effectively improves the integrity and stability of spinel structure of CuAl2O4, but also enhances its ability to dissociate and activate H species through interfacial sites of CuO-OV-CuXCo1-XAl2O4, thus further enhancing its catalytic conversion ability of CO2 to CO. These results enrich the understanding of surface chemistry of CuAl2O4 spinel and lay an important theory foundation for design of spinel-based catalysts for RWGS reaction. [Display omitted] •The RWGS reaction catalyzed by CuAl2O4 and CuxCo1-xAl2O4 was investigated.•CuAl-800 and Cu0.8Co0.2Al2O4 exhibit the best catalytic performance.•The formation of Cu2O deactivated CuAl2O4 during RWGS reaction.•Interfacial site of CuO-OV-CuXCo1-XAl2O4 was more stable than CuO-OV-Al2O3 site.•The mechanisms of RWGS reaction catalyzed by CuAl2O4 and CuxCo1-xAl2O4 were proposed.