铈钴复合氧化物催化剂催化CO-SCR反应机理研究

利用共沉淀法制备了一系列Ce-Co-O_x复合氧化物催化剂，并对其CO-SCR反应性能进行了研究.考察了Co和Ce比例对CO-SCR反应活性的影响，确定最佳的Ce和Co复合比例为3：7，最高转化率为84%（250℃）.经表征分析发现，Ce（0.3）-Co（0.7）-O_x上发生CO-SCR的主活性位点是Co.掺杂Ce提升催化性能主要有两方面原因：一是催化剂比表面积增大，提高了表面的吸附位数量；二是Ce-Co-O_x催化剂形成的固溶体提升了氧迁移率.反应机理可能是气态或者弱吸附状态的CO与NO的吸附物种（主要是桥接二齿亚硝酸盐物种和螯合式双齿硝酸盐物种）反应.

Mechanism study on CO-SCR over Ce-Co-Ox mixed oxides catalysts

In this paper, a series of Ce-Co-O_x catalysts were prepared by co-precipitation method and the CO-SCR performance was studied. The influence of Co and Ce ratio on the activity of CO-SCR was investigated and the Ce(0.3)-Co(0.7)-O_x sample showed the highest NO conversion efficiency of 84% at 250℃. According to characterization results, it was proposed that the active sites for CO-SCR is Co in Ce(0.3)-Co(0.7)-O_x. There were two reasons responsible for the enhanced catalytic performance by Ce doping into the Ce-Co-O_x catalyst. Firstly, the specific surface area and adsorption capacity were increased with Ce doping. Secondly, a solid solution was formed in Ce-Co-O_x catalyst, resulting in the enhanced oxygen migration rate. In situ DRIFTs results suggested that the CO-SCR is likely to follow a mechanism that gaseous or weakly-adsorbed CO reacts with adsorbed NO species in the forms of bridging bidenate nitrite and chelate nitrate.