鸡蛋壳负载Co_(3)O_(4)催化剂制备及其N_(2)O分解性能研究

Preparation of eggshell supported Co_(3)O_(4)catalyst and tested for N_(2)O decomposition

采用废弃的鸡蛋壳作载体,沉积沉淀法制备了一系列不同Co_(3)O_(4)含量Co_(3)O_(4)/鸡蛋壳催化剂,并在连续流动微反装置上考察了N_(2)O分解性能。结果表明,当Co_(3)O_(4)质量分数为20%时,催化剂表现出优异的N_(2)O分解性能。在空速10000 h^(−1)和N_(2)O含量0.1%的条件下,400℃可实现N_(2)O完全转化;其比活性约为Co_(3)O_(4)催化剂的4.3倍(反应温度为440℃);同时,该催化剂对原料气中3%O_(2)、3.3%H_(2)O和/或2.0×10^(−4)NO表现出较强的耐受性和较高的稳定性。分析催化剂的多种表征结果发现,CaCO_(3)作为鸡蛋壳的主要成分,与活性组分Co_(3)O_(4)紧密结合,两者的强相互作用导致20%Co_(3)O_(4)/鸡蛋壳催化剂中产生更多的氧空位和Co^(3+);Co_(3)O_(4)氧化还原性能得到提高,Co−O键被有效削弱;此外,该强相互作用可提高20%Co_(3)O_(4)/鸡蛋壳催化剂表面碱性位点的强度,增大碱性位点数量,更易于转移电子而促进N_(2)O分解。

A series of Co_(3)O_(4)/eggshell catalysts with different Co_(3)O_(4)contents were prepared by the deposition-precipitation method using discarded eggshells as supports,and tested for the catalytic reaction of N_(2)O decomposition on a fixed-bed continuous flow micro-reactor.The activity test results show that the catalyst exhibits higher activity towards N_(2)O decomposition when the mass fraction of Co_(3)O_(4)is 20%,with a specific activity of 4.3 times to that of pure Co_(3)O_(4)(reaction temperature 440℃).At the same time,it shows strong resistance to 3%O_(2),3.3%H_(2)O and/or 2.0×10^(−4)NO in feed.Various characterization results indicate that the predominant composition of eggshell is CaCO_(3),which has a close incorporation with Co_(3)O_(4).The strong interaction between CaCO_(3)and Co_(3)O_(4)contributes to producing more oxygen vacancies and Co^(3+)in the 20%Co_(3)O_(4)/eggshell catalyst.The redox performance of Co_(3)O_(4)is improved,and the Co−O bond is effectively weakened.In addition,it helps to increase the strength and amount of basic sites on the catalyst surface,making it easily transfer electrons and promote N_(2)O decomposition.