Co-Mn复合氧化物催化剂催化低浓度瓦斯燃烧性能的实验研究

Experimental study on catalytic performance of Co-Mn composite oxide catalyst for low concentration gas combustion

为了探究Co-Mn复合氧化物催化剂催化低浓度瓦斯燃烧性能,采用共沉淀法制备了钴锰物质的量比分别为1∶1和7∶3的Co-Mn复合氧化物催化剂,并用于低浓度瓦斯催化燃烧,利用SEM、BET、XRD、H_(2)-TPR、XPS等分析测试法,表征其催化性能。结果表明:钴锰物质的量比为7∶3时,催化剂呈蠕虫状结构堆积,而钴锰物质的量比为1∶1的催化剂呈现明显的球状结构;钴锰物质的量比为7∶3时催化剂具有更大的比表面积及更多的氧空位和活性氧,表现出更强的催化活性,其甲烷转化率为10%、50%和90%时的温度θ_(10)、θ_(50)和θ_(90)分别为364、466及587℃,分别比钴锰物质的量比为1∶1的催化剂降低了46、91和103℃。在Co-Mn复合氧化物催化剂中钴以Co^(3+)、Co^(2+)形式存在,而锰表现为Mn^(3+)、Mn^(4+)两种价态。

This paper is aimed at exploring the catalytic performance of Co-Mn composite oxide catalyst for low-concentration gas combustion.The study works by preparing Co-Mn composite oxide catalysts with the molar ratio of Co and Mn by 1∶1 and 7∶3 with coprecipitation method,which is used for low-concentration gas catalytic combustion;and characterizing the catalytic performanc by means of SEM,BET,XRD,H_2-TPR and XPS.The results show that the catalyst is piled with wormy structure as the content ratio of cobalt and manganese materials by 7∶3,while an obvious spherical structure presented with the content ratio by 1∶1.When the catalyst with the ratio of cobalt manganese at 7∶3 has a larger specific surface area,more oxygen vacancies and active oxygen,thus showing stronger catalytic activity.The temperature θ_(10),θ_(50) and θ_(90) at the methane conversion rate of 10%,50% and 90% are 364,466 and 587 ℃ respectively,which are 46,91 and 103 ℃ lower than the catalyst with the ratio of cobalt manganese material by 1∶1.In Co-Mn composite oxide catalyst,cobalt exists in the form of Co~(3+)and Co~(2+),while manganese has two valence states:Mn~(3+) and Mn~(4+).