Preparation And Soot Combustion Performance For Potassium-Containing Catalysts

In recent years,haze weather occurs frequently and threats the health of human beings seriously.Soot emission from diesel vehicle exhaust is one of the main reasons for its formation.The diesel particulate filters?DPF?technology,at the present stage,is one of the most effective methods to control soot emission,whose core is developing highly active catalyst.Alkali metal catalysts,especially those containing potassium,have attracted much attention due to their low price and excellent activity.This paper focuses on the problem of potassium loss and its role in catalyzing the soot combustion.A temperature-driven method was used to make the K limited in the HWO channel and wash out the K that did not enter the channel,so as to explore the role of the K limit in the channel.It was found that K could exist stably in the pore channel and maintained a stable catalytic effect.In addition,it was found that HWO was easy to change phase at high temperature while its phase transition was inhibited in the presence of channel K,that is,the channel K can maintain HWO phase stability while acting as a stable catalyt.Furthermore,different K precursors?K₂SO₄ and KNO₃?were used for verification,and the same conclusion was obtained.At the same time,the minimum amount of potassium nitrate with load to maintain phase stability and the saturation amount of potassium nitrate with load into the channels were further explored under the temperature drive of 500?.It was found that the load of 4.5wt%K was the minimum one,and the load of 6wt%K could make the K of HWO channels reach saturation.Meanwhile,the minimum amount of potassium nitrate with load to maintain phase stability and the saturation amount of potassium nitrate with load into the channels were further explored under the temperature drive of 500?.It was found that the load of 4.5wt%K was the minimum amount to maintain phase stability of HWO,and the load of 6wt%K could make the K of HWO channels reach saturation.In practical applications,noble metal monolithic catalysts have always been dominant,and K monolithic catalysts with excellent activity are worth further discussion due to their low price.In this paper,Ce based oxide?CePrO and CeZrO?was used as the support,and the traditional coating process was used to optimize the catalyst particle size,binder selection and content,slurry pH value,as well as the peeling of the monolithic catalyst and other parameters,and to explore the preparation of the optimal K-based monolithic catalyst and the performance of the catalytic elimination of soot particles.The optimal conditions for each parameter were as follows:the particle size of the 9 h wet ball mill catalyst was the smallest,the pH of the slurry was 6.5 and the coating amount was the best when 8%al sol binder was used.The monolithic catalyst prepared by traditional coating process is easy to fall off.In order to solve the problem,the in-situ growth catalyst on two monolithic substrates,silicon carbide and cordierite,was further studied.By growing ZnO nanorods in the whole matrix support channel,K was further loaded.It was found that ZnO nanorod could effectively intercept soot and increase the amount of soot capture,on the other hand,it could weaken the interaction between K and the support and disperse K,so that K could give full play to its catalytic performance.Both cordierite and silicon carbide support,the whole catalyst for growing ZnO nanorods and reloading potassium showed excellent catalytic performance for soot combustion.