PREPARATION AND CHARACTERIZATION OF NANOCRYSTALLINE Ce_(0.45)Zr_(0.45)La_(0.10)O_(2-δ) FOR METHANE OXIDATION REACTORS

摘要

Nanocrystalline Ce_(0.45)Zr_(0.45)La_(0.10)O_(2-δ) powder was prepared by organic-free modification of the sol-gel technique. Crystallization of amorphous precursor starts at 600℃ and results in the formation of highly dispersed (4/5 nm) cubic fluorite solid solution, stable up to 1100℃. The ESR studies showed that the incorporation of La(Ⅲ) into the Zr_(0.5)Ce_(0.5)O_2 lattice leads to increasing concentration of Ce~(3+) defects. This may contribute to the high catalytic activity towards partial oxidation of dry methane. The methane oxidation on composite Ce_(0.45)Zr_(0.45)La_(0.10)O_(2-δ)/Pt anodes in a model SOFC-type reactor provided 73% CO selectivity with 54 % conversion efficiency at 900℃ and CH_4:O_2 ratio equal to 2.