Web Release Date: October 16,
Effect of Jahn-Teller Distortion in La0.5Sr0.5MnO3 Cubes and Nanoparticles on the Catalytic Oxidation of CO and CH4
Department of Chemistry, Tsinghua University, Beijing 100084, P. R. China
Received: June 25, 2007
In Final Form: August 28, 2007
Abstract:
La0.5Sr0.5MnO3 cube and nanoparticle catalysts were synthesized by the hydrothermal and coprecipitation
method, respectively. The catalytic performances for CO and CH4 oxidation were evaluated, and the effect
of Jahn-Teller distortion on the catalytic performance was elucidated. La0.5Sr0.5MnO3 nanoparticle catalyst
showed a higher activity than the cube catalyst for CO oxidation at a lower temperature. While the catalytic
activity of the cubes significantly increased at higher temperature, the complete conversion temperatures for
CO were both the same at 210 
C. The trend for CH4 oxidation activity was similar to the trend observed for
CO oxidation activity. The catalytic mechanism of CO oxidation over La0.5Sr0.5MnO3 cubes is proposed that
the adsorbed CO was oxidized by the lattice oxygen. Then, the chemisorbed oxygen over La0.5Sr0.5MnO3
cubes was transformed into the lattice oxygen by MnO6 octahedra to reinforce the consumed lattice oxygen.
The catalytic performances of La0.5Sr0.5MnO3 cubes and nanoparticles were mainly predominated by Jahn-Teller distortion of the catalysts.
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