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采用共沉淀法制备了系列CexMn10-xO20-δ固溶体氧化物甲烷燃烧催化剂,并采用XRD和BET对所得催化剂进行了表征。结果表明,在适当的Ce/Mn摩尔比范围内,试样经500℃焙烧可形成Ce/Mn固溶体复合氧化物,更高焙烧温度则导致催化剂比表面积下降和一定程度的烧结。500℃和800℃焙烧催化剂的活性变化规律略有不同,其活性主要由Ce/Mn摩尔比决定,其中活性最高的催化剂中Ce/Mn摩尔比为7:3。100 h稳定性试验结果表明,经800℃焙烧的Ce3Mn7O20-δ催化剂具有良好的热稳定性。典型催化剂在低转化率下的宏观动力学实验结果表明, 甲烷催化燃烧在CexMn10-xO20-δ固溶体氧化物催化剂上为一级动力学反应,反应速率受催化剂固有性质控制。
A series of CexMn10-xO20-δ solid solution oxide methane combustion catalysts were prepared by coprecipitation method. The catalysts were characterized by XRD and BET. The results show that the Ce / Mn solid solution composite oxide can be formed by calcination at 500 ℃ within the proper molar ratio of Ce / Mn. The higher calcination temperature leads to the decrease of specific surface area and the sintering to some extent. The activity changes of the catalyst calcined at 500 ℃ and 800 ℃ are slightly different. The activity is mainly determined by the molar ratio of Ce / Mn. The molar ratio of Ce / Mn in the catalyst with the highest activity is 7: 3. The stability test results show that, The Ce3Mn7O20-δ catalyst calcined at 800 ℃ has good thermal stability. The results of macroscopic kinetics of typical catalysts at low conversion show that the catalytic combustion of methane is a first order kinetic reaction on the CexMn10-xO20-δ solid solution oxide catalyst, and the reaction rate is controlled by the inherent properties of the catalyst.