Investigation On Preparation And Performance Of CO Preferential Oxidation Catalysts In Hydrogen-rich Gas

Seeking for suitable catalysts for CO preferential oxidation (PROX) in methanol-reforming gas is important, especially for the application of methanol stream reforming technology in electric vehicles. From this viewpoint, CuO and Au supported catalysts were prepared and their catalytic performance for preferential oxidation of CO in hydrogen-rich gas was investigated in this dissertation. The correlations between crystal structure and catalytic performance were studied, with the aid of AAS,BET,XRD,TPR,UV-vis and TEM measurements.1,Effect of reaction conditions on the performance of PROX of CO on the CuO/CeO₂ catalysts was investigated. It was found that at high temperature region, the conversion increased and the selectivity decreased, with increasing the value ofλ(λ=2×C_O2/C_CO)in the reaction gas; while with increasing the space velocity, a contrary result was observed, i.e. the conversion decreased and the selectivity increased. Therefore, under the premise of high CO conversion, decreasing the value ofλand increasing the space velocity is facilitated to improve the selectivity of the catalysts.2,Effect of preparation conditions on the catalytic performance of catalysts for PROX of CO was investigated. Catalysts screening studies revealed that CuO/CeO₂ catalyst can show higher activity at 100-170℃and suitable calcination temparature and CuO content can improve the dispersion of CuO on the support, and little addition of Al2O3 to the low CuO loading catalysts can improve the performance of PROX of CO. The CuO/CeO₂ catalyst that calcinated under 650℃with 4.9wt.% CuO and 1.0wt.% Al2O3 showed the best performance of PROX of CO, and it possessed excellent thermal stability, e.g. no obvious decreasing of activity was observerd even the catalyst was carried out in the feed gas for 160h.3,The characterize results of the catalysts before and after HNO3 treatment showed there are three states of CuO in the catalyst, among which the high dispersion CuO and the CuO on the boundary of Cu-O-Ce are closely related to the PROX of CO.4,The principium study on the Au catalysts indicated that, Au/Fe2O3 can show high CO conversion varies from 0 to 100℃, but the selectivity is weak. Through suitable preparation condition the same performance on the Au/CeO₂-ZrO2 will be achieved. The comparation of the catalytic performances of Au/ZSM and Au/ZSM-Fe₂O₃ catalysts showed that the activity is caused by the interation between the Au and Fe2O3.In all, it was found that the high conversion and the high selectivity region of CuO and Au catalysts are different, while CuO/CeO₂ might be a more potential catalyst when...