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

It is of great importance to extend ethanol-blended gasoline both in alleviating energy crisis and improving environmental quality. The paper investigated the transitional metal doped Ce0.67Zr0.33O2 in auto-exhaust catalysts for the unburned ethanol, acetaldehyde, and so on, which supplied the theory support for developing the exhaust catalysts for ethanol-blended gasoline.The complex compounds of M0.05Ce0.63Zr0.32Ox and M0.1Ce0.6Zr0.3Ox (M= Mn, Fe, Co, Ni and Cu) were synthesised by a citric acid sol-gel method. The structures were characterized by XRD, Raman, TPR, XPS and EPR measurements, and the activity of ethanol complete oxidation and dynamic oxygen storage capacity (DOSC) over all samples were tested. Three-way catalysts (TWC) activity was tested over 0.5wt.%Pd/M0.05Ce0.63Zr0.32Ox and 0.5wt.%Pd/M0.1Ce0.6Zr0.3Ox by incipient wetness impregnation method.The results of XRD and Raman showed that the transitional metal ions incorporated into the lattice of Ce0.67Zr0.33O2, and all fresh samples exhibited a distinct fluorite-type cubic structure in forming M-Ce-Zr-O solid solution. After calcined at 900℃, it is not observed that transitional metal phase for M0.05Ce0.63Zr0.32Ox, and the 10% samples of Mn, Fe and Ni. Through the XPS and EPR techniques, it revealed that the states and the chemical environment of transitional oxides. TPR results showed the species of transitional metal oxides.The activity of complete oxidation of ethanol over M0.1Ce0.6Zr0.3Ox was better than that of M0.05Ce0.63Zr0.32Ox. The DOSC of all the fresh samples was higher than that of Ce0.67Zr0.33O2. It indicated that the addition of transition metal enhanced the mobility of lattice oxygen in Ce0.67Zr0.33O2,which is favorable for the complete oxidation of ethanol and DOSC. For TWC performance over 0.5wt.% Pd loaded samples, the Ni doped sample performed better than the other samples even after aging. In summary, Ni doped samples showed higher performance on complete oxidation of ethanol, DOSC and TWC activity after loading Pd,except deactivation after aging.