Study On Preparation Methods And Denitrification Performance Of Manganese-based Montmorillonite Low Temperature SCR Catalysts

To explore the preparation method,the preparation parameters and the structure effect relationship of the lamellar support,the Mn-based montmorillonite catalyst was prepared by the impregnation method,co-precipitation method,and in-situ growth method.The stability of the catalyst and its potential for industrial applications were tested.At the same time,an experimental idea for the preparation of the Mn-based montmorillonite catalysts with one-step pillared-loaded was proposed.The main contents are as follows:?1?Three kinds of lamellar materials?Montmorillonite,Kaolinite,and Expanded graphite?were selected as carriers,and the best carrier-montmorillonite was selected by in-situ growth method.The performance of the Mn-based montmorillonite catalysts prepared by impregnation method,co-precipitation method,and in-situ growth method was compared.The results show that the catalyst prepared by the in-situ growth method has the best activity.The NO conversion rate can reach 90%at 100?,and the NO conversion rate is close to 100%in the temperature range of 125-250?.At 100?,the NO conversion rate of the catalyst prepared by co-precipitation method was 83%,which was close to the activity of the in-situ growth method after 150?.The activity of the catalyst prepared by the impregnation method is relatively poor.At 100?,the NO conversion rate is only 5%,and the overall activity does not exceed 60%.The results show that the in-situ growth method can give full play to the advantages of montmorillonite lamellae.The active component of the catalyst has small grains and good dispersibility.The specific surface area reaches 100.2 m²?g^-1,and it has strong redox capacity and a large number of acid sites.Compared with the impregnation method,the co-precipitation method can effectively reduce the crystallinity of the active component through precipitation decomposition loading,improve the stability of the carrier,and make the catalyst have a higher specific surface area and a stronger redox capacity.?2?The relationship between the preparation parameters?precursor,reactant ratio,and Mn loading?and the catalyst physicochemical structure and activity was discussed.The stability of the catalyst Mn10MMT-SP and the activity performance under different space velocity were tested.The results show that the catalyst prepared with manganese acetate as the precursor,the reactant ratio KMn O₄:Mn?AC?₂=2:3,and the Mn loading of 10 wt%has the best denitration performance.Increasing the proportion of reactant KMn O₄within a certain range can increase the concentration of Mn⁴⁺on the surface of the catalyst to regulate the high activity temperature range of the catalyst.The specific surface area of the catalyst and the number of acid sites are adjusted by changing the loading amount when the Mn loading amount is low.Besides,the active component has a certain supporting effect on the montmorillonite sheet,so the catalyst shows good stability at 100-300?,and has excellent industrial application potential.In short,the in-situ growth and co-precipitation method has a high matching with montmorillonite.One-step pillared-loaded of Mn can be achieved,the active components have a higher dispersion,and form a rich number of active sites and a relatively stable structure.