Preparation, Characterization And Catalytic Performance Of Porous Cerium Copper Based Nano Catalytic Materials

In recent years, the greenhouse effect, resource depletion and other problems caused by the use of fossil energyhave become increasingly prominent.Hydrogen as a safe, non-polluting and renewable new energy, has attracted widespread attention. The proton exchange membrane fuel cells (PEMFCs) are regard as one of the most promising technologies to utilize hydrogen. However, The resultant H2-rich gases always contain a small quantity of CO (0.3-1%), which will be seriously poisoning the Pt-based PEMFC anode. Among the various methods developed for CO removal, CO preferential oxidation (CO PROX) is believed to be one of the most effective ways.Noble metal catalysts and non-noble metal catalyst are two category catalysts which are used in preferential oxidation of CO in hydrogen rich gas. Copper-ceria based catalysts have become a promising candidate as a representative of non-noble metal catalysts.CeO2-CuO based non-precious metal catalysts have wide source of raw materials, cheaper and a higher conversion rate of CO, better selectivity of CO2.They have good catalytic activity at higher temperature. However, such catalyst temperature window is narrow, which limited their practical application.In the first chapter, we reviewed hydrogen, fuel cells, and research status of catalytic materials used in hydrogen-rich atmosphere of CO preferential oxidation.In the second chapter, we used colloidal crystals as a template, synthesized a series of porous CeO2-CuO catalytic materials via thermal decomposition of precursor. The obtained CeO2-CuO based catalytic materials exhibit connected ordered macroporous structure, pore size of about 200 nm. What’s more, There are 3-4 nm mesoporous exsit, which formed macroporous-mesoporous structure. This may be due the gas produced by thermal decomposition during calcination. The catalytic materials have large specific surface areas because of such structures’ formation. We also tested their CO PROX reactivity in hydrogen-rich gas. The results showed that by modulating the Ce/Cu atomic ratios and the doping amounts of Fe2O3 and CO3O4, the superior catalytic performance of CeO2-CuO catalysts with high CO conversion, CO2 selectivity and longer-term stability in a wide operation temperature window is achieved.In the third chapter, we synthesized porous CuO/CeO2 catalytic materials with various CuO loading via bubbler assisted deposition-precipitation method. The obtained porous CuO/CeO2 catalytic materials have uniform pore sizes, large specific surface areas. The catalytic performance of CO preferential oxidation in H2-rich gases showed that CO selectivity increases with CuO loadings rises when CuO loading reaches to 10 wt%.The 10 wt % Cu catalytic materials exhibited excellent catalytic performance with high CO conversions. In this condition, the active species are prone to exposed, and combined with TPR data, we know that CuO is in the form of highly dispersed status located in the CeO2 surface.The synergistic effect between highly dispersed CuO and CeO2 are in favor of preferential oxidation of CO.In the forth chapter, we summarized the research work in this thesis, and did some prospect for the research in the future.