Research Of Deactivation Mechanism And Regenerative Performance Over CeO₂/CuO Catalysts For Preferential Co Oxidation

Hydrogen has been considered as the most clear energy. The proton-exchange membrane fuel cell (PEMFC) is one of the fuel cells, which convert chemical energy to electrical energy. The reforming of hydrocarbons is considered to be the most feasible method to produce large amount of hydrogen-rich. PEMFC anode is highly sensitive to the presence of even trace amount of CO. Hence, it is essential to keep the CO concentration below100ppm in order to promote the use of the PEMFC. CO-PROX is the simplest and efficient approach for purifying hydrogen. CuO/CeO2catalyst has been drawing more and more attention for its low cost and high catalytic performance.The solvothermal method was used to prepare the CuO precursor with cotton-ball-like morphology in order to obtain the CeO2/CuO catalysts with high BET surface area. The study shows that Both CeO2and CuO exist in form of crystallization and they interact on the contact interface. The interaction of oxides switches on CO oxidation at55℃and the synergistic effect of interaction also improve H2oxidation at95℃. CO oxidation takes place at the contact interface of CeO2and CuO. The high BET surface area and good dispersion of catalysts can be more helpful for the presence of accumulated long periphery at interface of CeO2and CuO than the larger CeO2particles when most of CeO2particles pile into the small clusters and distribute on the bulk CuO. The catalyst has the highest BET surface area and better dispersion of CeO2among the catalysts, therefore it display good catalytic activity, selectivity and stability.The hydrothermal and impregnation methods were used to prepare the CeO2/CuO-X catalysts with spherical structure. The study shows that the microspheres of CuO consist of the sheet-like CuO and the way of arrangement results in the formation of shell structure. There is a core in the middle of shell structure, which is composed of the nano-sized CuO particles. CeO2particles are supported on the surface of the CuO microspheres or embedded in the pores of sheet-like CuO. It is found that there is another reason for the decrease of CO conversion above155℃except H2competitive oxidation. It is from the change of the CeO2/CuO catalyst during CO-PROX reaction including the reduction of CuO and the separation of metallic copper from the surface of catalyst.The CuO supports with different morphologies were prepared using hydrothermal and precipitation methods. A series of inverse CeO2/CuO catalysts were prepared with different morphologies of CuO supports. The study shows that the CeO2/CuO catalysts possess discrepant structural, textural properties and interface interaction of CuO and CeO2, thus the CeO2/CuO catalysts presents different catalytic performance. CO is chemisorbed on Cu+ions on the interface of CuO and CeO2. The reduction of CuO and the production of carbonate, hydrogen carbonate and formate species may lead to the deactivation of the catalysts. The re-calcined catalysts possess larger particles, weaker interface interaction and poorer catalytic performance, which could further prove that the Cu+at the interface is the active center for the CO-PROX.