期刊
CHEMCATCHEM
卷 9, 期 17, 页码 3330-3337出版社
WILEY-V C H VERLAG GMBH
DOI: 10.1002/cctc.201700647
关键词
cobalt; dehydrogenation; mesoporous materials; self-assembly; spinel phases
资金
- Dow Chemical Company
- DOE Office of Science by Argonne National Laboratory [DE-AC02-06CH11357]
A mesoporous CoAl2O4 spinel (Co-Al) is synthesized by a one-step evaporation-induced self-assembly (EISA) method. N-2 physisorption and TEM are used to demonstrate the presence of mesopores within the Co-Al material. The spinel crystal structure of Co-Al, in which Co occupies tetrahedral (T-d) sites, is confirmed by using XRD and UV/Vis spectroscopy. In nonoxidative propane dehydrogenation at 550 degrees C, a propane conversion of approximately 8% is observed for Co-Al with a >80% propylene selectivity, which corresponds to a turnover frequency of 5.1h(-1) based on an estimation of the number of active Co sites by using NH3 temperature-programmed desorption. A much higher propane conversion rate and a circa 80% propylene selectivity is observed upon reaction at 600 degrees C. Continuous deactivation of the catalyst is observed for Co-Al at this elevated temperature. Insitu X-ray absorption spectroscopy results suggest that Co remains as a T-d Co2+ species under the reaction conditions. The T-d Co2+ sites within the Co-Al material are thus proposed to act as Lewis acidic active sites; this acidity is verified using IR spectroscopy with pyridine as a probe molecule.
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