Effect of the variation of metal and cerium loadings on CeO2x–TiO2(100−x) supports in the complete catalytic oxidation of formaldehyde

Abstract

Formaldehyde has been successfully converted into CO2 and H2O at low temperature in the presence of CeO2x–TiO2(100−x) mixed oxides prepared by the sol–gel method. A high selectivity in CO2 was observed with the Ce50Ti50 catalyst. In order to improve the selectivity of the reaction by-products, the Ce50Ti50 was doped with 5 wt% of different transition metals (Ni, Co, Cu, Fe) by impregnation and then activated by reduction under H2. These catalysts have shown excellent catalytic results, which followed the activity order: Co/Ce50Ti50 > Cu/Ce50Ti50 > Ni/Ce50Ti50 > Fe /Ce50Ti50 > Ce50Ti50. Cu/Ce50Ti50 was the most selective solid for the production of CO2. ICP analyses have shown a similarity between the experimental and theoretical values of the metal amount. Physisorption measurements have revealed the mesoporous texture of the solids with large specific surface areas. The XRD analyses exhibited the presence of anatase and cubic phases of Ce50Ti50 mixed oxide. XPS profiles and TEM Images for the best catalyst, Cu/Ce50Ti50, showed that copper particles were identified on the support. From OSC and H2–TPR measurements, the OSC values increase with the Ceria loading on the support increasing the reducibility of the material.