Optimization of Preparation Factors for Cerium Oxide Synthesis as a Support for CO PrOx Catalyst

Abstract

Nanocrystalline ceria has been considered as support for carbon monoxide preferentially oxidation. In this study ceria was prepared by precipitation method and the effects of preparation conditions, such as pH of solution (8-10), aging time (1-12 hr), drying temperature (80-120 °C), calcination time (2-6 hr) and temperature (400-600 °C) were investigated on ceria synthesized powders properties. Nanocrystalline ceria were characterized by thermal gravimetric analysis (TGA), X-ray diffraction (XRD) and ASAP analysis. Calcination temperature and pH of solution have the highest effect on powder specific area. Finally, optimum conditions for the synthesis of cerium oxide in this study are pH = 10, aging time = 6 hr, drying temperature = 120 °C, calcination time = 6 hr, and temperature = 500 °C. Crystalline size of ceria is lower than 20 nm and in the shape of sphere-like and maximum surface area is 74.45 m2/g. 7%CuO/CeO2 catalyst was prepared by wetness impregnation method and was tested in catatest for oxidation of CO in presence of hydrogen (preferentially oxidation, PrOx). The CO conversion and CO2 selectivity was achieved 57.3 – 98% and 83-40% by temperature increasing from 80-180 °C, respectively.