钙钛矿型催化剂La_(1-x)K_x CoO_(3-λ)的表征特性及对柴油机尾气中NO_x催化性能的研究  

Study on Catalytic Activity of Perovskite-Type Oxides La_(1-x)K_x CoO_(3-λ) for the Removal of NO_x from Diesel Exhaust Gases

作　　者：黄齐飞[1] 宋崇林[1] 范国梁[2] 吕刚[1] 李小娟[1] 赵瑞芬[2] 

机构地区：[1]天津大学内燃机燃烧学国家重点实验室,天津300072 [2]天津大学材料学院,天津300072

出　　处：《燃烧科学与技术》2006年第5期413-418,共6页Journal of Combustion Science and Technology

基　　金：国家重大基础研究发展计划(973)资助项目(2002CB211606);国家自然科学基金(50506020);天津市自然科学基金(033603911).

摘　　要：采用柠檬酸络合燃烧法制备了K^+部分取代La^(3+)的La_(1-x)K_xCoO__(3-λ)钙钛矿型催化剂,使用XRD、STEM和化学分析等方法对催化剂的组成和结构进行了表征,并利用程序升温反应研究了催化剂对柴油机尾气中NO_x的净化催化活性．实验结果表明,K^+部分取代A位La^(3+)会导致复合氧化物La_(1-x)K_xCoO_(3-λ)的晶体结构及组成发生变化．当取代量x≤0．3时,La_(1-x)K_xCoO_(3-λ)为单相的钙钛矿型复合氧化物；x≥0．4时,催化剂样品中出现CO_3O_4,且其含量随着取代量x的增大而增大．La_(1-x)K_xCoO_(3-λ)催化剂对于柴油机尾气中NO_x的净化有较好的催化活性；当x=0．3时,催化剂表面氧空位量最大,对柴油机尾气中NO_x的净化效率最高,在450℃时可达50%．在催化剂作用下,柴油机排放颗粒物(PM)的存在提高了NO_x的净化效率．A series of perovskite-type oxides La1 -x KxCoO3-λ were prepared with citric acid method. The structure and component of the catalysts were studied systematically by means of chemical analysis, X-ray diffraction （XRD） ,and transmission electron microscope （TEM）. Moreover, the catalytic activity for the removal of NOx from diesel exhaust gases of these perovskite-type mixed oxides was also investigated by temperature programmed reaction （TPR）. The experimental resuhs indicate that the crystal structure and component of La1-x Kx CoO3-λ will be altered with partial substitution of K^＋ for La^3＋. La1-x KxCoO3-λ is single perovskite phase in the case of x ≤0.3. And when x≥ 90.4, Co3O4 appears in the catalyst samples and increases with the increase of x. La0.7 K0.3 CoO3-λ behaves the greatest amount of oxygen vacancy and shows the highest catalytic activity for the removal of NOx with 50% at 450 ℃. The presence of diesel particulate matters （DPM） could improve catalytic activity for NOx removing.

关 键 词：柴油机 NOx净化 钙钛矿型催化剂 催化性能 氧空位 

分 类 号：TQ54[化学工程—煤化学工程]