Fabrication of Hollow Spheres of Copper-Cerium Composite Oxide for Catalytic Decomposition of Nitrous Oxide
Tetsuo UMEGAKI, Hiroki SHIRAISHI, Yoshiyuki KOJIMA
This work investigated fabrication of hollow spheres of copper-cerium composite oxide for catalytic decomposition of nitrous oxide. The hollow spheres were obtained via coating of copper-cerium composite oxide shell on spherical silica templates, followed by leaching process in aqueous sodium hydroxide solution to remove the templates. The obtained hollow spheres with various copper contents consisted of spherical particles with a diameter of c.a. 130-150 nm and the internal cavity of c.a. 100 nm, which reflected the size of silica templates. The catalytic activity of the hollow spheres with high copper content for decomposition of nitrous oxide significantly improved with increasing reaction temperature and the conversion of nitrous oxide reached 78% at 773 K. From XPS spectra of the samples before and after the catalytic reaction, the peak assigned as Ce4+ species in Ce 3d region shifted toward higher binding energy, and the degree the peak shift was lower in the spectra of the sample with higher copper contents. The results of the activity tests and XPS spectra suggested that the hollow spheres without significant change of valence state of Ce species showed higher activity for catalytic decomposition of nitrous oxide.
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