High thermal-stability ceria synthesized via thermal-hydrolysis route and methane-combustion performance

Enhancement of the thermal stability of a catalyst is an efficient way to improve the catalytic activity of a catalytic reaction performed at high temperature. In this study, cerium oxide (ceria, CeO2) with a high thermal stability was synthesized by controlling the agglomeration of the primary particles via the thermal hydrolysis of ceric nitrate, accompanied by testing for the catalytic combustion of methane (CH4). The specific surface area of this material after calcination at 1,173 K for 5 h was 50 m2/g, which was much higher than that of the two reference materials (ceria made via precipitation of cerous nitrate using aqueous ammonia at 4.1 m2/g, and the Japan reference catalyst JRC-CEO-1 at 1.4 m2/g). The ceria made via thermal hydrolysis showed high crystallinity and a much higher pore volume, which resulted in excellent thermal resistance. For O2 conversion in ceria, catalyzed CH4 combustion at 923 K, the ceria created in this study demonstrated higher activity than that for either reference. The high CH4 combustion performance was due to the high specific surface area and to a superior oxygen storage capacity (OSC) even after a combustion test.