Pt/MnOx-CeO2 catalysts for the complete oxidation of formaldehyde at ambient temperature

MnOx-CeO2 mixed oxides with a Mn/(Mn + Ce) molar ratios of 0-1 were prepared by a modified coprecipitation method and investigated for the complete oxidation of formaldehyde. The MnOx-CeO2 with Mn/(Mn + Ce) molar ratio of 0.5 exhibited the highest catalytic activity among the MnOx-CeO2 mixed oxides. Structure analysis by X-ray powder diffraction and temperature-programmed reduction of hydrogen revealed that the formation of MnOx-CeO2 solid solution greatly improved the low-temperature reducibility, resulting in a higher catalytic activity for the oxidation of formaldehyde. Promoting effect of Pt on the MnOx-CeO2 mixed oxide indicated that both the Pt precursors and the reduction temperature greatly affected the catalytic performance. Pt/MnOx-CeO2 catalyst prepared from chlorine-free precursor showed extremely high activity and stability after pretreatment with hydrogen at 473 K. 100% conversion of formaldehyde was achieved at ambient temperature and no deactivation was observed for 120 h time-on-stream. The promoting effect of Pt was ascribed to enhance the effective activation of oxygen molecule on the MnOx-CeO2 support. (C) 2007 Elsevier B.V. All rights reserved.