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 473K. 100% conversion of formaldehyde was achieved at ambient temperature and no deactivation was observed for 120h time-on-stream. The promoting effect of Pt was ascribed to enhance the effective activation of oxygen molecule on the MnOx–CeO2 support.