| Recently, at the pressure of environment pollution and energy crisis, proton exchange membrane fuel ceils, as a clean and efficient energy resource, have attracted more and more attentions. As for one of the key techniques of fuel cells, the preferential oxidation of carbon monoxide in excess hydrogen has become the hot field in the past years.In the present dissertation, the influence of preparation methods on the catalytic performance of ceria supported copper catalysts in the preferential oxidation of carbon monoxide in excess hydrogen has been investigated and ceria supported copper catalysts and their application in the preferential oxidation of carbon monoxide in excess hydrogen have been studied in detail. Furthermore, the influence of preparation conditions of co-precipitation method and the doping of metals on the catalytic performance of catalysts have been investigated extensively. Finally, the mechanism of the reaction over ceria supported copper catalysts and the influence of reaction conditions have also been studied. Some valuable results, as shown in the following, have been achieved.Firstly, the catalytic performance of ceria supported copper catalysts prepared by different methods such as mechanical mixing, impregnation, coprecipitation and chelating methods in the preferential oxidation of carbon monoxide in excess hydrogen is compared and ceria supported copper catalysts prepared by coprecipitation and chelating methods are found to possess a higher catalytic performance in the preferential oxidation of carbon monoxide in excess hydrogen.Secondly, the influence of preparation conditions on the catalytic performance of ceria supported copper catalysts in the preferential oxidation of carbon monoxide in excess hydrogen has been studied and a nano-structured catalysts with high catalytic performance have been prepared, which has a catalytic performance as well as, if not better than, that of precious metal-based catalysts and those reported in literatures. At a space velocity of 120 000 ml g-1 h-1 and a reaction temperature of 120℃, carbon monoxide conversion and selectivity are 99.5% and 87.5%, respectively. Furthermore, carbon monoxide conversion is kept at 99.3% even at 145℃and a temperature window with a high carbon monoxide conversion is formed.In addition, the influence of different metal doping on catalysts has also been investigated. It is found that doping of K+ enhances the endurance of water and carbon dioxide. However, the doping of over content K depresses the activation of catalysts. Therefore, an appropriate content of K+ (0.10wt%) is beneficial to improve the catalytic performance of catalysts in the presence of water and carbon dioxide. The catalytic performance of catalysts doped with Fe and Co is improved in the absence of water and carbon dioxide, especially for Co-doped catalysts achieved a wide temperature window with a high CO conversion higher than 99.0%, while the catalytic performance of catalysts doped with other transitional metals such as Mn, Ni and Zn is depressed. Further more, the doping of transitional metals (Mn,Zn,Fe,Co,Ni) has an important influence on the catalytic performance of the catalysts in the presence of water and carbon dioxide. The catalytic performance of catalysts doped with Fe, Mn and Zn is improved, however, doping of Co, Fe, Mn and Zn has a negative effect on the selectivity of catalysts in the preferential oxidation of carbon monoxide. As for rare earth metals (Nd, Pr, Y and La), the doping has no effect on the catalytic performance of the catalysts in the absence of water and carbon dioxide even though the selecitvity of the catalysts is improved. However, the doping of Nd enhances the catalytic performance of catalysts in the presence of water and carbon dioxide, while the selectivity of catalysts doped with Nd, Pr, Y and La has a pronounced improvement.In the end, the copper oxide species, according to the dispersion and valence of copper, are classified as following:(a) Copper oxide associated tightly with surface oxygen vacancies.(b) One-, two- and three-dimension copper oxide entities.(c) The Cu+ stabilized by oxygen vacancies.(d) Bulk copper oxides etc.Furthermore, according to the contact between copper oxide and oxygen vacancies, there exist strong, weak and null interactions, which play an important role in the sygnism and the catalytic performance in the preferential oxidation of carbon monoxide in excess hydrogen.
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