溶液燃烧制备镧基钙钛矿及其催化碳烟燃烧性能

Lanthanum-based perovskite catalysts prepared by solution combustion method and its catalytic performance for soot combustion

采用溶液燃烧法制备不同B位过渡金属元素(Mn、Fe、Co、Ni)的La基钙钛矿(LaMO_(3))催化剂,并考察少量Sr部分取代La对催化剂性能的影响;通过XRD、SEM、BET、H_(2)-TPR、XPS方法对催化剂进行理化性质表征,采用程序升温氧化(TPO)技术评估催化剂催化碳烟燃烧的性能。结果表明:溶液燃烧法制备的La基催化剂具有典型的钙钛矿结构,少量Sr掺杂不改变催化剂的晶型;Sr掺杂LaMnO_(3)引起的电荷不平衡由增加的Mn^(4+)补偿,Sr掺杂LaCoO_(3)使吸附氧量明显提高;La_(0.9)Sr_(0.1)MnO_(3)和La_(0.9)Sr_(0.1)NiO_(3)的氧化还原性能相比掺杂Sr之前的有所下降,La_(0.9)Sr_(0.1)FeO_(3)表面吸附氧物种量增多,催化剂的低温氧化还原性提升;气氛中NO_(x)的存在可进一步降低催化碳烟燃烧温度,La_(0.9)Sr_(0.1)CoO_(3)催化剂具有最好的催化活性,催化碳烟燃烧的t_(50)(质量分数为50%的碳烟转化温度)为369℃,生成CO_(2)选择性SCO_(2)为100%。

La-based perovskite(LaMO_(3))catalysts with different B-sites transition mental elements(Mn、Fe、Co、Ni)were prepared by solution combustion method,and the effect of partial substitution of La by a small amount of Sr on the catalyst performance was investigated.The catalysts were characterized physicochemically by XRD,SEM,BET,H_(2)-TPR and XPS,and the performance of the catalysts for catalytic carbon soot combustion was evaluated by temperature-programmed oxidation(TPO).The results show that the La-based catalysts prepared by solution combustion method have a typical perovskite structure,and the crystal morphology of the catalysts is not changed after Sr doping.The charge imbalance caused by Sr doping LM is compensated by the increase of Mn^(4+).Sr doping LC significantly increases the amount of adsorbed oxygen.The redox performance of LSM and LSN are lower than that of Sr-free samples and the amount of oxygen species adsorbed on LSF surface increases,which improve the low temperature oxidation reducibility of the catalyst.The LSC catalyst has the best catalytic performance among these catalysts,with the t_(50) of catalytic soot combustion=369℃ and S_(CO_(2))=100%.