Water-Gas-Shift Reaction on Au/TiO2–x Catalysts with Various TiO2 Crystalline Phases: A Theoretical and Experimental Study

Au supported on TiO2 (Au/TiO2) catalysts have shown excellent activity in low-temperature water-gas-shift (LT-WGS) reaction; however, the effects of different crystalline phases of the support, the oxygen vacancies (Ov) on the support, and the metal-support synergy on the catalytic performance still...

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Published in:Journal of physical chemistry. C 2021-09, Vol.125 (37), p.20360-20372
Main Authors: Yin, Pan, Yu, Jun, Wang, Lei, Zhang, Jian, Jie, Yao, Chen, Li-Fang, Zhao, Xiao-Jie, Feng, Hai-Song, Yang, Yu-Sen, Xu, Ming, Zhang, Xin, Han, Jing-Bin, Yan, Hong, Wei, Min
Format: Article
Language:English
Subjects:
C: Chemical and Catalytic Reactivity at Interfaces
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Summary:Au supported on TiO2 (Au/TiO2) catalysts have shown excellent activity in low-temperature water-gas-shift (LT-WGS) reaction; however, the effects of different crystalline phases of the support, the oxygen vacancies (Ov) on the support, and the metal-support synergy on the catalytic performance still remain indistinct. In this work, a combination of density functional theory (DFT) calculation, microkinetic modeling, and experimental investigation for the LT-WGS reaction mechanism over the Au8 cluster supported on TiO2 with three crystalline phases (Au/ana-Ov, Au/rut-Ov, and Au/bro-Ov) is systematically performed. Notably, Au/ana-Ov gives the lowest energy barrier at each step of the WGS reaction, indicating a superior catalytic activity, and a redox pathway is confirmed: H2O undergoes the dissociation adsorption on Ov while interface Au serves as an active site for CO activation. The microkinetic modeling results confirm the favorable operating condition (p H2O/p CO ≤ 4) for this reaction. Furthermore, experimental researches verify that the Au/ana-Ov sample exhibits the optimum catalytic activity, which accords well with the prediction conclusions of theoretical calculation. This work provides the detailed information on the metal-support synergistic catalysis as well as the in-depth understanding of the reaction mechanism of LT-WGS over the Au/TiO2–x system, which would pave a way for the development of heterogeneous catalysts toward interface sensitive reactions.
ISSN:1932-7447
1932-7455
DOI:10.1021/acs.jpcc.1c06381