柴油车尾气四效组合催化剂的研究  

Study on the combined catalysts for four-way purification of emission from diesel engine

作　　者：荆延妮 赵震[1] 许洁[1] 刘坚[1] 徐俊峰[1] 

机构地区：[1]中国石油大学重质油国家重点实验室,北京102249

出　　处：《工业催化》2009年第8期7-10,共4页Industrial Catalysis

基　　金：国家自然科学基金(20833011;20803093);北京市自然科学基金(2062020);国家高技术研究发展计划(863计划)(2006AA06Z346)

摘　　要：提出设计双层组合催化剂净化新技术,即碳黑氧化燃烧催化剂床层和NOx还原催化剂床层的组合,该组合催化剂对柴油机尾气四种污染物的消除具有较高的催化活性。采用浸渍法制备了Al_2O_3负载不同量的La_(0.8)K_(0.2)MnO_3和相同负载量、不同K含量的La_(1-x)K_xMnO_3/Al_2O_3催化剂作为氧化催化剂处理碳烟、CO和HC;采用等体积浸渍法制备Cr/HZSM-5、Mo/HZSM-5、W/HZSM-5三系列催化剂作为还原催化剂处理NOx,并将其进行组合,得到优良的氧化还原组合催化剂,同时处理柴油车尾气中的四种污染物。在模拟柴油车尾气组成条件下,用乙炔代表烃类物质并采用固定床微型反应装置,考察了所制备的双层四效组合催化剂净化柴油车尾气的催化性能。研究发现,负载质量分数为50%的La_(0.5)K_(0.5)MnO_3/A1_2O_3和负载量为1.42×10^(-4)mol.g^(-1)的W/HZSM-5组合催化剂对于同时消除柴油车尾气NO、碳颗粒、CO和HC有较好的效果。NO还原为N_2的转化率在反应温度范围最高可达79%,同时碳颗粒的燃烧峰值温度为448℃,碳颗粒燃烧生成CO_2的最大选择性可达98%,乙炔完全转化的温度为364℃,从而实现了四种有害物质的同时催化净化。A new technology was proposed for designing double-layer combined catalysts including ‘oxidativecatalysts’ for soot oxidation and ‘reductive catalysts’ for NOx reduction,which provides an high activity for controlling the four kinds of pollutants emitted from diesel engines.For oxidation of the soot,CO and HC,La_(0.8)K_(0.2)MnO_3 supported on Al_2O_3 with different loadings and La_(1-x)K_xMnO_3/Al_2O_3 with different loadings of K were prepared by impregnation.Cr/HZSM-5,Mo/HZSM-5 and W/HZSM-5 were prepared for decomposition of NOx via SCR reaction.The oxidation and reduction catalysts were combined to treat the four pollutants from diesel engines.Catalytic activity of the double-layer four-way catalysts were tested on a fixed-bed microreactor under reaction condition simulating the emission streams from diesel engines and using acetylene as the model compounds for HC.The results showed that catalysts consisting of La_(0.5)K_(0.5)MnO_3/Al_2O_3 (with loadings of 50wt%) and W/HZSM-5 (with loadings of 1.42×10^(-4) mol·g^(-1)) effectively oxidized PM,CO,HC and reduced NO,with maximum NO-to-N_2 conversion of up to 79% ,peak temperature for the soot combustion of 448 ℃ ,maximum selectivity for soot combustion to CO_2 of 98% and temperature for complete conversion of acetylene of 364 ℃,attaining simultaneous catalytic abatement of the four pollutants.

关 键 词：催化剂工程 柴油机 四效催化剂 钙钛矿 ZSM-5分子筛 

分 类 号：TQ426.96[化学工程] X701[环境科学与工程—环境工程]