La1-xKxMnO3催化剂同时消除柴油机尾气中NO和碳烟性能

Simultaneous removal of NO and soot from diesel engines over La1-xKxMnO3 catalysts

采用溶剂热法制备La1-xKxMnO3(x=0,0.10,0.15,0.20,0.25)钙钛矿型复合金属氧化物催化剂;通过XRD、FT-IR、SEM、H2-TPR、XPS、NO-TPD等手段对催化剂的物相组成、表面形貌、氧化还原性能等进行了表征;在常压固定床微型反应装置中评价催化剂同时消除NO和碳烟催化性能.结果表明,制备的La1-xKxMnO3催化剂均具有钙钛矿结构;K部分取代La-Mn钙钛矿结构中La后,颗粒结构得以改善,部分Mn^3+价态升高为Mn^4+,形成较多氧空位和Mn^4+,提高氧化还原性能和吸附NO性能.活性评价结果表明,La0.80K0.20MnO3催化剂表现出较好的同时消除NO和碳烟催化性能,NO最大转化率(XNO2^max)和对应反应温度(TNO2^max)分别为46.5%和436℃,碳烟起燃温度(Tig)、CO2浓度峰值温度(TCO2^max)和生成CO2选择性(SCO2^max)分别为341℃、454℃和98.8%.

La1-xkxMnO3(x=0,0.10,0.15,0.20,0.25)perovskite oxide catalysts were prepared by solvothermal method.Various methods such as XRD,FT-IR,SEM,H2-TPR,XPS and NO-TPD,were used to characterize structure,composition,surface morphology,and the redox properties of the catalysts.Their catalytic performance of the simultaneous NO and soot removal was investigated in a fixed-bed micro-reactor under atmospheric pressure.The results indicated that the La1-xKxMnO3 catalysts showed perovskite structure.For La1-xKxMnO3 catalysts,with the partial substitution of La^3+ by K^+ in the Mn-based perovskite lattice,a portion of Mn^3+ was transformed into Mn^4+ and the number of oxygen vacancies was increased,leading to an improvement of the redox properties and NO adsorption performance.As a result,the catalytic reactivity of La0.80K0.20MnO3 catalyst was also improved,achieving the simultaneous removal of NO and soot.The maximum conversion of NO(XNO2^max)and the reaction temperature(Tmax)were 46.5% and 436℃,respectively.The ignition temperature of soot(Tig),peak CO2 formation temperature(TCO2^max)and CO2 selectivity(SCO2^max)were 341℃,454℃ and 98.8%,respectively.