Preparation Of Specific Morphology Oxides And Catalytic Performance For Soot Combustion

Soot particulates from diesel engines cause serious harm to the environment and human health.DPF（diesel parts filters）can effectively reduce the emission of soot,thus highly active catalysts are desirable.The specific catalysts with the morphology of nanosheets,nanorods,nanowires,and three-dimensionally ordered macropores,usually show good catalytic activity.Genrally,this increases catalyst and soot contact efficiency.Furthermore,many exposed active sites can promote catalytic activity.On the basis of above facts,we prepared MnO_x/LaMnO₃ catalysts with a flaky structure by the citric acid complex method and the selective dissolution.The physico-chemical properties of prepared catalysts are characterized by XRD,BET,SEM,HAADF,XPS,H₂-TPR and O₂-TPD.TPO tests are used to investigate catalytic activity for soot combustion.The as-prepared catalysts show excellent catalytic activity.The ignition temperature can be lowered to about 200 ^oC.Furthermore,the activity is mainly attributed to the flaky MnO_x.Finally,the intrinsic activity of the catalysts is investigated by the TOF（turnover frequency）test.The LMO-6h sample shows the highest TOF value.Since potassium（K）has excellent catalytic activity for soot combustion,we introduce K into LaMnO₃ by doping method in order to prepare the LaKMnO₃ precursor.Selective dissolution method is also used to obtain the MnO_x/LaKMnO₃ catalysts.The physico-chemical properties of prepared catalysts were characterized by XRD,BET,TEM,HAADF and H₂-TPR.The catalytic activity for soot combustion was studied by TPO test.The results show that MnO_x/LaKMnO₃ has better catalytic activity than MnO_x/LaMnO₃ under the same test conditions.For practical application purpose,we have prepared ZnO nanorods on DPF support material Al₂TiO₅ by hydrothermal method,and then loaded K onto ZnO/Al₂TiO₅.The structure and morphology of the as-prepared catalysts were characterized by XRD and SEM.The catalytic activity for soot combustion was studied by TPO test.It is shown that the monolithic catalyst has good catalytic activity.