Synthesis Of High Efficient Photothermal Copper-Cerium Catalysts And Catalytic Performance For CO Preferential Oxidation

CO in H₂-rich stream can easily lead to Pt anode poisoning in proton exchange membrane fuel cell（PEMFC）.Preferential oxidation of CO（CO-PROX）is considered as a promising strategy to purify H₂ source and prevent Pt electrode poisoning.Copper-cerium composite oxide catalyst has good thermal catalytic CO-PROX performance.However,in view of the high energy consumption and low energy utilization efficiency in the thermal catalytic process,this thesis focuses on using sunlight as the driving source to develop efficient copper-cerium composite oxide for photothermal synergistic catalysis,so as to purify CO in H₂ source more efficiently and energy saving.In this thesis,a solid-gas photothermal catalytic reaction system is developed,in which CO preferential oxidation reaction is carried out directly under simulated sunlight without external heating source.In this thesis,two kinds of copper-cerium composite oxide catalysts with morphology and pore structure were prepared.Not only was the strong interaction between copper and cerium used to improve the catalytic performance of PROX,but also the good photothermal and optical properties of copper-cerium oxide semiconductors were used to successfully realize the high-efficiency photo responsive thermal catalytic preferential oxidation of CO.The specific research contents and conclusions are as follows:（1）Nanorod copper-cerium oxide with uniform morphology was prepared by rapid and simple coprecipitation method.Its physicochemical properties were regulated by changing the proportion of copper and cerium in the catalyst.The result shows that the Cu-Ce nanorods with 10 wt.%copper content can reach a specific surface area that is more than 100 m²/g.Moreover,copper species are highly dispersed in the bulk phase and surface of the catalyst,and the catalyst has rich oxygen defect structure and strong copper-cerium interaction.Compared with pure cerium dioxide,copper-cerium composite oxide has greater absorption and photogenerated carrier ability in the visible band,and effectively inhibits the recombination of photogenerated carriers,reaching0.34μA/cm² photocurrent density.The surface temperature of the catalyst can reach97℃under 250 m W/cm² light,showing a CO conversion efficiency of 90%.（2）A three-dimensional homogeneous porous copper-cerium oxide material was prepared which SiO₂ microspheres was used as a template,showing a uniform porous structure with a specific surface area of 125 m²/g.The three-dimensional homogeneous porous catalyst has higher surface oxygen defect concentration and highly dispersed copper species,showing stronger copper-cerium interaction.Compared with the three-dimensional inhomogeneous porous catalyst,the uniform pore structure enhances the visible light absorption capacity of the catalyst,and improves the separation efficiency and carrier life of photogenerated carriers,and the photocurrent reaches 0.4μA/cm²current density.The three-dimensional homogeneous porous catalyst can reach a temperature of 100℃and a CO conversion efficiency of 83%under 200 m W/cm²light.（3）The mechanism of CO preferential oxidation of copper-cerium composite oxide under photothermal catalysis is discussed in this thesis.By comparing the photocatalytic and thermal catalytic properties of the catalyst,it is found that the photothermal effect is the main driving force for the PROX reaction of copper cerium oxide.Under the irradiation of different light intensities and bands（visible light,infrared light,ultraviolet light,etc.）,the light response ability of copper-cerium composite oxide materials is different.Their strong absorption ability of visible light leads to the obvious increase of catalyst surface temperature and high CO oxidation ability.Under the stable irradiation of 2-2.5 simulated sunlight,the higher temperature on the surface of the catalyst accelerates the recombination of photogenerated carriers,and the contribution of photocatalytic reaction reduces.The reaction is characterized by photo-induced thermal catalytic oxidation.