Study On Preparation Technology And Peformance Evaluation Of Mn-Ce/TiO₂ SCR DeNO_x Catalyst

In order to effectively control NO_x emissions of marine diesel engines, IMO has enacted strict emissions regulations, research on strengthening the NO_x emission control technology is imperative. As an effective denitration measure for exhaust after treatment, the technology of selective catalytic reduction （SCR） as a method has been widely used. However, the problems that catalyst has low catalytic activity and catalyst sulfur poisoning within the scope of low temperature have restricted the application and the development of low temperature SCR technology. To solve the problems above, on the basic of the study on SCR catalytic reaction mechanism, Mn-Ce/TiO₂ catalyst activity at low temperature is studied, including its preparation, bench test and so on,and analyses the experimental results.Firstly, based on orthogonal test scheme, honeycomb Mn-Ce/TiO₂ catalysts with different load are made, and the effects of these load on the SCR denitration performance and the reaction condition through SCR activity test and catalyst characterization test is studied.Then, in order to further improve the activity of Mn-Ce/TiO₂ catalyst, this paper continues to load catalyst metal elements（Cu、Cr、Co、Fe） on Mn-Ce/TiO₂ to study the effect of metal elements on the activity of Mn-Ce/TiO₂ catalyst. Finally, Mn-Ce/TiO₂ catalyst sulfur poisoning is studied.Catalyst characterization test results show that, Mn-Ce/TiO₂ catalysts loaded CeO_x can greatly improve the performance of the catalyst activity at low temperature. the best ratio of Mn-Ce/TiO₂ catalyst load is Mn（9%）-Ce（2.5%）/TiO₂（15%）. Metal elements can promote the activity of the catalyst, Co performs more significantly. It is found that the denitration rate of Mn-Ce-Co/TiO₂ catalyst can reach as high as 98.95% when Co loading amount is 15%. SCR activity test results show that,reaction temperature and ammonia ratio have a significant impact on NO removal rate, while velocity and NO concentration have a less significant impact on NO removal rate. When the condition for the SCR activity test is as follows:reaction temperature at 250℃, NH3/NO=1, NO concentration at 750ppm, space velocity at 12000h-1, the denitration rate of Mn-Ce/TiO₂ catalyst is the best. The results through theoretical analysis show that, Mn-Ce/TiO₂ catalyst is suitable for application in the marine environment. Doping metal elements can improve Mn-Ce/TiO₂ catalyst sulfur tolerance.The results of this research, achieved from making the new honeycomb Mn-Ce/TiO₂ catalyst and from studying SCR performance of Mn-Ce/TiO₂ catalyst at low temperatures through interactive orthogonal tests, have great significance for future studies and application of medium-Low temperature SCR technology, particularly in the area of marine industry.