Catalytic oxidation of carbon monoxide over nanostructured CeO2–Al2O3 prepared by combustion method using polyvinyl alcohol

Abstract

The catalytic oxidation of carbon monoxide over nanostructured CeO2–Al2O3 mixed oxide powders prepared by gel combustion method using polyvinyl alcohol and metal nitrates as starting materials was studied in this paper. The prepared samples were characterized by thermal analysis, X-ray diffraction, field-emission scanning electron microscopy and Brunauer–Emmett–Teller nitrogen adsorption method at 77K. The effects of molar ratios of starting materials, pH value of precursor solution and calcination temperature on phase formation, phase composition and morphology of prepared samples were investigated. The dependence of CO conversion efficiency on Ce/Al molar ratio was also studied. The results showed that the bee's nest-like nanostructure with the pore wall consisting of CeO2–Al2O3 mixed oxide nanocrystals was observed for samples calcined at temperatures in the range of 600–850°C. For the optimized sample with this nanostructure, an average grain size of 10nm, an average pore size of 300nm, a specific surface area of 87.5m2/g, and a CO conversion efficiency as high as 99.7% at 160°C were obtained.