柴油机尾气碳颗粒燃烧中La-Mn-Fe-Cu/HZSM-5的催化性能

采用柠檬酸络合浸渍法制备分子筛负载钙钛矿型金属复合氧化物催化剂。采用XRD、SEM、XPS和H₂-TPR等手段对催化剂性能进行表征,并在微型固定床反应器中对催化剂进行活性评价。结果表明,B位离子由多种金属离子组成的催化剂,可使碳颗粒燃烧温度降低,生成CO₂的选择性高。B位离子种类及配比直接影响催化剂性能,Cu离子加入可提高生成CO₂的选择性,Co离子加入可降低碳颗粒燃烧温度,调节Fe/Mn离子摩尔比可以改善碳颗粒燃烧温度和生成CO₂的选择性。其中,LaMn_0.2Fe_0.7Cu_0.1O₃/HZSM-5催化剂性能较好,碳颗粒燃烧温度较低,T_ig、T_m和T_f分别为236.6、419.0和458.7 ℃,生成CO₂选择性较高,为88.3%。

Catalytic performance of La-Mn-Fe-Cu/HZSM-5 catalysts for soot combustion from diesel exhaust

The catalysts of perovskite-type complex oxide loaded on HZSM-5 zeolite were synthesized.The catalysts were characterized by XRD,SEM,XPS and H2-TPR,and their performance for combusting soot was evaluated in a fixed micro-reactor.The results show that when B-site ion was consisted of various metals,the catalytic performance was improved,the soot combustion temperature decrease,and the selectivity forming CO2 increased.The performance of catalysts was affected by the species and component of B-site ion.The selectivity forming CO2 increased and the temperature of soot combustion reduced when Cu and Co ion was in B-site,respectively.The temperature of soot combustion and selectivity forming CO2 was improved with changing the mole ratio of Fe/Mn.Among them,LaMn0.2Fe0.7Cu0.1O3/HZSM-5 catalyst has better performance with lower combustion temperature of Tig,Tm and Tf at 236.6,419.0 and 458.7 ℃,respectively,and higher selectivity forming CO2 of 88.3%.