期刊
JOURNAL OF CATALYSIS
卷 300, 期 -, 页码 225-234出版社
ACADEMIC PRESS INC ELSEVIER SCIENCE
DOI: 10.1016/j.jcat.2013.01.010
关键词
Raman spectroscopy; Operando; Kinetics; CO oxidation; Manganese oxides; alpha-Mn2O3 nanocrystals; Temperature-programmed surface reaction
资金
- Chinese Education Ministry 111 project [B08021]
- National Science Foundation [21176071, 21106041, 21273070]
- Shanghai PuJiang Talent Program [2011/11PJ1402400]
- Science and Technology Commission of Shanghai Municipality [11JC1402700]
- Innovation Program of Shanghai Municipal Education Commission [11ZZ52, 12ZZ051]
- Shanghai Natural Science Foundation [11ZR1408400]
- Fundamental Research Funds for the Central Universities
alpha-Mn2O3 nanocrystals with uniform morphology prepared by calcining a self-assembled Mn3O4 precursor have proved active (ca. 0.14 molecule nm(-2) s(-1) at 153 degrees C) toward CO oxidation at low temperatures. The reaction orders with respect to CO and O-2 were measured in the temperature range 100-190 degrees C. Operando and in situ Raman spectroscopy are used to determine the near-surface structure of alpha-Mn2O3 nanocrystals during the adsorption and oxidation of CO for the first time. A surface phase transformation from alpha-Mn2O3 to MnjOk (1 < j < 2, 1 < k < 3, and 1 < k/j < 1.5) intermediate species was observed in gaseous CO with the change in temperature. In addition, with the combination of the temperature-programmed desorption of O-2, temperature-programmed surface reaction of CO oxidation, operando Raman spectra, and kinetics parameters, we conclude that the oxidation of CO may proceed through the Langmuir-Hinshelwood mechanism (<200 degrees C) to the Mars van Krevelen mechanism (>350 degrees C) with increasing reaction temperature. In particular, the adsorbed oxygen is deduced to be responsible for CO oxidation at lower temperatures. (C) 2013 Elsevier Inc. All rights reserved.
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