期刊
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
卷 138, 期 19, 页码 6298-6305出版社
AMER CHEMICAL SOC
DOI: 10.1021/jacs.6b02762
关键词
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资金
- National Natural Science Foundation of China (NSFC)
- 973 Program [2014CB932104]
- China National Funds for Distinguished Young Scientists of the NSFC
Oxygen vacancy on the surface of metal oxides is one of the most important defects which acts as the reactive site in a variety of catalytic reactions. In this work, operando spectroscopy methodology was employed to study the CO2 methanation reaction catalyzed by Ru/CeO2 (with oxygen vacancy in CeO2) and Ru/alpha-Al2O3 (without oxygen vacancy), respectively, so as to give a thorough understanding on active site dependent reaction mechanism. In Ru/CeO2 catalyst, operando XANES, IR, and Raman were used to reveal the generation process of Ce3+, surface hydroxyl, and oxygen vacancy as well as their structural evolvements under practical reaction conditions. The steady-state isotope transient kinetic analysis (SSITKA)-type in situ DRIFT infrared spectroscopy undoubtedly substantiates that CO2 methanation undergoes formate route over Ru/CeO2 catalyst, and the formate dissociation to methanol catalyzed by oxygen vacancy is the rate-determining step. In contrast, CO2 methanation undergoes CO route over Ru surface in Ru/alpha-Al2O3 with the absence of oxygen vacancy, demonstrating active site dependent catalytic mechanism toward CO2 methanation. In addition, the catalytic activity evaluation and the oscillating reaction over Ru/CeO2 catalyst further prove that the oxygen vacancy catalyzes the rate -determining step with a much lower activation temperature compared with Ru surface in Ru/alpha-Al2O3 (125 vs 250 degrees C).
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