Application Research Of Transitional Metal Doped CeO₂ In Auto-Exhaust Catalysts For Ethanol-blended Gasoline

The ethanol-blended gasoline adapts to the stratagem of nationwide energy replacement and sustainable energy development, and furthermore, this fuel is favorable for the national energy security, agriculture development and the improvement of atmospheric environment. This paper investigated the transitional metal doped CeO₂ in auto-exhaust catalysts especially for the emissions of unburned ethanol, and guided the improvement direction of exhaust catalysts for ethanol-blended gasoline.The solid solutions of M_0.05Ce_0.95O)x and M_0.1Ce_0.9O_x (M = Mn, Fe, Co, Ni, Cu) were prepared by a citric acid sol-gel method. The structure analysis was done by XRD, Raman, BET, TPR, XPS and EPR measurements, and the activity of ethanol completely oxidation and dynamic oxygen storage capacity over solid solutions were tested. Three-way catalysis (TWC) activity was tested over Pd/M_0.05Ce_0.95O_x and Pd/M0.1Ce0.9Ox.Results showed that: Mn, Fe, Co, Ni and Cu doped ceria still kept the ceria-like fluorite cubic structure when the doping amount was less than 10mol%. The Mn, Fe oxides had better thermal stability in solid solution, whereas other transitional metal oxides separated out from solid solution after calcined at 900℃. The activity of ethanol completely oxidation and dynamic oxygen storage capacity on fresh samples were improved by Mn, Fe, Co, Ni and Cu doping and enhanced with the doping amount increasing, due to the various oxidation state of transitional metal and interaction in solid solutions.For TWC performance over 0.5wt.% Pd loaded samples, the Co doped sample performed better than other samples even after aging.In a word, Mn doped samples had better performance on ethanol completely oxidation, dynamic oxygen storage capacity and TWC performance, except deactivate after aging.