Research Of Catalytic Performance And Active Sites Over Au/CuO-CeO₂ Catalysts For Preferential CO Oxidation

Hydrogen has been considered as an ideal and efficient clean energy. As one of the most important technology in hydrogen utilization, the fuel cells attract worldwide attention because of its high-efficiency and no pollution. The proton exchange membrane fuel cell (PEMFC) is one of the most typical applications. However, trace amount of CO in the hydrogen feed gas for the large-scale production degrades the performance of the electrodes which are highly sensitive to the presence of CO. Hence, it is essential to reduce the CO concentration below 100 ppm. The preferential oxidation of CO is a simple and cost-effective technique for performing this ultimate CO removal. As the catalysts for CO-PROX, the copper-ceria catalyst has been obtained the widespread application for its lower cost, higher stability and selectivity, while the gold catalysts has captured attention due to their high activity at low-temperature for the CO oxidation process.In this dissertation, the active support of CuO and CeO2 were selected to support the gold nanoparticles. The gold catalyst Au/CuO-CeO2 was obtained in order to explore influences of the content of Au, the preparation method and the support effect on the catalytic performance for the CO-PROX. The main contents of the thesis are as follows:1. The Au/CuO-CeO2 catalysts with different Au contents were prepared using the co-precipitation method in order to study the effect of Au content on the catalytic performance and the modifying procedures between copper and ceria. With the calculation of TOF, the active sites were also investigated. The study shows that there is obviously crystal growth occurring in the gold modifying procedures for CuO. CO oxidation takes place at the interface of CuO-CeO2 catalyst. The large CuO particles and high content of Au are benefit to form more active sites. The interaction of CuO and CeO2 are facilitated, which lead to the super performace.2. A series of Au/CuO-CeO2 catalysts were prepared by the different methods in order to investigate the influences of preparation method and compared with Au/CeO2 and CuO-CeO2. It is found that the cooperative effect between CuO-CeO2 and Au is observed, high low-temperature activity and good stability would be obtained. The main advantages of the Au/CuO-CeO2 catalyst prepared by liquid-phase reductive deposition are related to the higher utilization ratio of Au, smaller unique particle size and more active species Auδ+, which benefit its high performance.3. The CuO-CeO2 catalysts were prepared via a co-nanocasting replication method and applied to prepare Au catalysts, in order to study the effect of textural property on the CO-PROX performance. The study shows that the CuCeK40 sample prepared using mesoporous silica KIT-6 aged at 40℃ possess higher BET (up to 150m2/g), larger pore size and volume and high interaction between copper and ceria, which benefit its super performance. In addition, for AuCuCe130 catalyst, the small pore size of CuCeK130 is benefit to highly disperse Au particles in pore due to its channel limit effect, which contributes to its super performance.