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研究报告

基金项目：国家自然科学基金项目(No.51108187,50978103);大气污染控制广东高校工程技术研究中心资助项目(No.GCZX-A0903);中央高校基本科研业务费(No.2012ZM0041,2011ZM0048)

叶代启
1. 华南理工大学环境与能源学院, 广州 510006;
2. 广东省大气环境与污染控制重点实验室, 广州 510006;
3. 大气污染控制广东高校工程技术研究中心, 广州 510006

摘要：用沉淀法制备了MnO_x和CeO₂两种催化剂并用于氧化模拟碳烟.XRD、BET、O₂-TPD和NO-TPD表征结果表明,CeO₂的比表面积和NO_x吸附容量更大,而MnO_x则具有更多的氧物种(晶格氧O^2-).TPO结果表明,气氛中引入的NO明显促进了碳烟的氧化.在无催化剂、加入CeO₂和MnO_x 3种情况下,模拟碳烟的起燃温度T_i分别降低了38、41和101℃.DRIFTs结果表明,催化剂活性氧物种和反应过程中生成的NO₃^-是NO促进碳烟燃烧的关键因子.可能的反应路径为:低温富氧条件下气相中的O₂吸附在催化剂表面上,丰富的活性氧物种(如O^2-、O₂^-和O^-)得到激活和转化,进而将弱吸附NO₂和活性NO₂^*氧化成NO₃^-;在高温时则释放出活性很强的NO₂^*和O^-,因而能促进碳烟氧化,其中间产物为碳氧复合物C(O).

Abstract：MnO_x and CeO₂ were prepared by precipitation method as catalysts for the oxidation of model soot. Characterization measurements of XRD, BET, O₂-TPD and NO-TPD demonstrated that CeO₂ exhibited greater surface area and NO_x adsorption capacity, while more oxygen species (lattice oxygen O^2-) were detected in MnO_x. TPO test revealed that NO in the feeding gases remarkably promoted soot oxidation. The ignition temperature T_i for soot oxidation decreased by 38℃ without addition of any catalyst, and decreased by 41℃ and 101℃ in the presence of CeO₂ and MnO_x, respectively. In situ DRIFTs showed that the reactive oxygen species on catalysts and NO₃^- formed in the reaction process were the key factors for promoting soot oxidation in the presence of NO. The possible pathways were: gaseous O₂ in the O₂-rich condition was adsorbed onto the surface of catalysts at low temperature, thus abundant reactive oxygen species(such as O^2-, O₂^- and O^-)were activated and transformed; the weakly adsorptive NO₂ and reactive NO₂^* were oxidized into NO₃^-; NO₃^- released reactive NO₂^* and O^- at high temperture in turn, therefore enhancing soot oxidation with C(O) complex as intermediates.