Study on Catalytic Properties of Nano-CeO_2-ZrO_2 Mixed Oxides Prepared by Modified Sol-Gel Method

The nanosized CeO_2-ZrO_2 solid solutions were prepared by modified Sol-Gel method with Ce(NO_2)_3-6H_2O and ZrO(NO_3)_2·2H_2O as starting materials.The effects of different Ce/Zr molar ratio and calcination temperature on the particle size,crystal type and reducibility were studied to obtain optimal preparation condition. CeO_2-ZrO_2 solid solution was characterized by XRD,SEM and TPR measurements.Results show that the highest specific surface area of CeO_2-ZrO_2 solid solution is 92m~2/g while Ce/Zr molar ratio is 3:1.CeO_2-ZrO_2 solid solution prepared by modified Sol-Gel method is fluorite structured.TPR results show that CeO_2-ZrO_2 solid solution calcined at 450℃has good catalytic reducibility.Catalytic properties are estimated through a fix-bed reactor under atmospheric pressure.CeO_2-ZrO_2 solid solution with Ce/Zr molar ratio of 3:1 show higher catalytic activity and selectivity to ethanol steam reforming reaction than those of CeO_2 and other molar ratio CeO_2-ZrO_2 solid solution. Both reducibility and heat stability of CeO_2 can be improved with the addition of ZrO_2.