Studies On Co₃O₄-CeO₂ And Composite Oxide Catalysts For CO Preferential Oxidation

As a new type of green energy, Fuel Cells have the advantages of fuel diversity,energy efficiency, environmental friendliness, which have been extensively studied in recent years. The proton exchange membrane fuel cell（PEMFC） shows its bright application prospect. In addition to the general advantages of fuel cells, the PEMFC also has the advantages of low temperature, long life, fast start,etc. Hydrogen, as the fuel of PEMFC, usually contains about 1% of CO, a trace amount of CO can lead to fuel cells electrode poisoning.CO preferential oxidation（PROX） can effectively reduce CO content to ppm level. As non-noble metal catalyst, the catalytic performance of the transition metal oxide catalysts can be compared with Pt series and other noble metal catalysts.The Co₃O₄-CeO₂ and its composite oxide catalysts were prepared by the co-precipitation.The samples prepared were characterized and analyzed by TEM,HRTEM,EDX, XRD, BET, TPR. And studied several aspects: Different cobalt cerium of the aCo₃O₄-bCeO₂ and the relationship between the catalytic properties and structures,addition of H₂O₂, Influence on the catalytic performance of aCo₃O₄-bCeO₂ catalysts doped with Mn and Cu, and the effects of sintering temperature. A series of data were obtained through the study.The study found that when Co/Ce ratio is 8:1,calcination temperature is 350℃,the8Co₃O₄-1CeO₂ catalyst has the largest specific surface area and the lowest reduction temperature than other catalysts and also showed the best catalytic performance, CO conversion rate can reach 100% at 155℃, the selectivity of catalyst was 100% at the time of CO fully converted. The addition of H₂O₂ did not improve the catalytic performance,the CO complete conversion temperature is reduced to 135 ℃ of the 8Co₃O₄-1CeO₂ catalyst without H₂O₂. The particle size of the catalyst was significantly decreased and the surface dispersion was improved after the addition of manganese and copper,also the interaction between Co-Ce was enhanced and the reduction temperature was decreased.The CO complete conversion temperature is 95℃ and 115℃ of 8Co₃O₄-1CeO₂-2MnO₂ and 8Co₃O₄-1CeO₂-1CuO.Without H₂O₂ or adding too little and too much additives will not effectively improve the catalytic activity of cobalt based catalysts. The CO complete conversion temperature is 135℃ and 175℃ of 8Co₃O₄-1CeO₂-2Mn O₂ and8Co₃O₄-1CeO₂-1CuO when the calcination temperature is 500℃. The rise of calcinationtemperature increased the sintering of catalyst, which lead to a decrease in the activity of the catalyst than the calcination temperature of 350 ℃.