不同方法制备Co3O4催化剂CO-SCR性能及机制

CO-SCR Performance and Mechanism over Co3O4 Catalysts

氮氧化物(NOx)是造成细颗粒物、近地面臭氧等大气污染问题的重要前体物.随着大气污染治理行动的深入,对工业锅炉/窑炉烟气排放的NOx进行控制十分重要.采用不同方法制备了一系列Co3O4催化剂,考察了不同制备方法对CO选择性催化还原NO(CO-SCR)反应活性的影响,通过BET、XRD、Raman、HR-TEM和SEM等技术对该系列催化剂进行了表征.活性测试表明,以硫酸钴为前驱体用固态研磨法制备的Co3O4-S催化剂具有更优异的CO-SCR反应活性,且表现出较好的抗水蒸气性能,以醋酸钴为前驱体用固态研磨法制备的Co3O4-C催化剂显示出较好的抗水性能.NO氧化结果显示,催化剂的NO氧化效果越好,CO-SCR活性也越好.Raman表征结果显示,Co3O4-S表面可能含有更多的Co^2+离子,从而有利于形成氧空位.H2-TPR结果表明,Co3O4-S催化剂的氧化还原性较好.HR-TEM表征发现Co3O4-S和Co3O4-O主要暴露(111)和(220)晶面,而更多(220)晶面的暴露可能更有利于反应的进行.

Nitrogen oxide (NOx ) is an important precursor for many air pollution problems such as fine particulate matter and groundlevel ozone.Because air pollution levels increase daily,it is important to control NOx emissions from industrial boiler flue gas.A series of different Co3O4 catalysts was prepared in this study by different methods.The effects of the preparation methods on selective catalytic reduction of NO by CO (CO-SCR) were investigated.The catalysts were characterized by BET,XRD,HR-TEM,and Raman.The results show that the Co3O4-S catalyst,prepared by solid grinding with cobalt sulfate as the precursor,had better CO-SCR activity and H2O resistance and that Co3O4-C,prepared by solid grinding with cobalt acetate as the precursor,showed excellent H2O resistance. The NO oxidation results showed that better NO oxidation activity over the catalysts is an important reason for the improved CO-SCR activity.The Raman results indicate that more Co ^2+ ions appeared on the surface of Co3O4-S,which benefited the formation of oxygen vacancies.The H2-TPR results showed better redox property of the Co3O4-S catalyst.The HR-TEM results shoes that the (111) and (220) crystal planes were exposed mainly on Co3O4-S and Co3O4-O and that more (220) crystal planes are conducive to improved reaction.