期刊
JOURNAL OF CATALYSIS
卷 257, 期 2, 页码 334-344出版社
ACADEMIC PRESS INC ELSEVIER SCIENCE
DOI: 10.1016/j.jcat.2008.05.012
关键词
perovskites; carbon; XPS; EELS; temperature-programmed oxidation
This work reports on the reactivity toward carbon of a La0.5Sr0.5CoO3-delta perovskite prepared by spray pyrolysis. It is shown that this perovskite presents a moderate activity for the thermal oxidation of carbon, producing a decrease in its temperature of combustion of ca. 150 degrees C and a significant increase in the selectivity toward CO2. Different experiments were carried out with electron energy loss spectroscopy (EELS) and X-ray photoemission spectroscopy (XPS) for the perovskite and its physical mixture with a high-surface area carbon material. In the physical mixture, the cobalt at the surface was partially reduced to Co2+ even at room temperature. XPS demonstrated a species of oxygen with low electron density at the catalyst surface. This species seemed to play a significant role in the oxidation processes at the perovskite surface. A model is proposed to account for the changes exhibited by the catalyst during its reaction with carbon. (c) 2008 Elsevier Inc. All rights reserved.
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