期刊
CATALYSIS TODAY
卷 258, 期 -, 页码 691-698出版社
ELSEVIER SCIENCE BV
DOI: 10.1016/j.cattod.2014.12.037
关键词
Carbon dioxide conversion; Carbon monoxide production; Isothermal reverse water gas shift chemical looping; RWGS-CL; Perovskites
资金
- NSF [1335817]
- USF School of Graduate Studies
- Directorate For Engineering
- Div Of Chem, Bioeng, Env, & Transp Sys [1335817] Funding Source: National Science Foundation
The RWGS-CL is a two-step process for the conversion of CO2 to CO using a redox cycle of a parent metal oxide. Previously, this process was demonstrated using La0.75Sr0.25CoO3 perovskite, but this material required different oxidation and reduction temperatures. In this study, oxidation and reduction were achieved at the same temperature. La0.75Sr0.25Co(1-Y)FeYO3 (Y = 0, 0.5, 0.75 and 1) perovskite-type oxides were synthesized by the Pechini method and were tested by X-ray diffraction (XRD), temperatureprogrammed reduction (H-2-TPR) and oxidation with carbon dioxide (CO2-TPO). Results demonstrated that the LaFeO3 (Y=1) sample showed structure stability when reduced at 550 degrees C, the lowest CO formation onset temperature (450 degrees C) and high selectivity toward CO. Five isothermal RWGS-CL cycles were performed at 550 degrees C on the Y=1 sample. The stability of the crystalline structure throughout the cycles was demonstrated by XRD. CO formation rates increased during the first cycles and stabilized at the third cycle due to the increased accumulated amount of oxygen vacancies (delta) on the perovskite surface, which is consistent with the findings from the density functional theory studies that directly correlate the CO2 binding strength to the amount of oxygen vacancies. The high CO formation rates and the repeatability of the process make RWGS-CL a promising technology for CO2 conversion, if a renewable hydrogen source is available. (C) 2015 Elsevier B.V. All rights reserved.
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