Effect of the A-site cation on methane oxidation of perovskite-type (La1−xMx)CoO3 (M=Ca, Sr, and Ba)

• Published in: Journal of solid state chemistry 2012-06, Vol.190, p.157-161
• Main Authors: Taguchi, Hideki, Matsu-ura, Keiko, Takada, Masao, Hirota, Ken
• Format: Article
• Language: English
• Subjects: Cations; Condensed matter: structure, mechanical and thermal properties; Conversion; Crystal structure; Exact sciences and technology; Inorganic compounds; Methane; Methane oxidation; Oxidation; Oxides; Oxygen content; Perovskite; Physics; Polymerizable complex method; Rietveld method; Specific surface; Strontium; Structure of solids and liquids; crystallography; Structure of specific crystalline solids
• ISSN: 0022-4596; 1095-726X
• DOI: 10.1016/j.jssc.2012.02.023

Perovskite-type (La1−xMx)CoO3 (M=Ca, Sr, and Ba) synthesized at 700°C in air using the polymerizable complex method had a rhombohedral perovskite-type structure in the range of x≤0.06. The oxygen content of the samples was 2.98–2.99, and the specific surface area was 3.5–8.3m2/g regardless of the M ion or x. The Rietveld method indicated that the Co–O distance was also constant regardless of the M ion or x, and that the Co–O–Co angle between two CoO6 octahedra increased with an increase in the ionic radius of the M ion. The temperature corresponding to the 50% conversion (T1/2) of CH4 oxidation was almost constant for the samples with x=0.04, while the T1/2 of the samples with x=0.06 was linearly lowered with increases in the ionic radius of the M ion. The conversion from CH4 to CO2 and H2O on (La0.94M0.06)CoO3 (M=Ca, Sr, and Ba). [Display omitted] ► (La1−xMx)CoO3 (M=Ca, Sr, and Ba) was synthesized using the polymerizable complex method. ► The Co–O distance was constant regardless of the M ion or x. ► The Co–O–Co angle increased with an increase in the ionic radius of the M ion. ► CH4 oxidation started above 300°C and finished at 700°C. ► The catalytic activity increased with increases in the ionic radius of the M ion.