Application Of Mn-Ce/ZSM-5 Denitration Catalyst For Diesel Exhaust Purification

In recent years,With the continuous popularization and application of diesel engines in the market,the environmental pollution caused by the nitrogen oxides?NO_x?emitted from diesel vehicle exhaust should not be underestimated.Selective catalytic reduction?SCR?removal from diesel exhaust NO_x is considered to be one of the most effective methods.This paper takes HZSM-5 as the carrier,Mn with excellent activity at low temperature was selected as the active component and screened by the introduction of metal elements,found that the 15%Mn-40%Ce/ZSM-5 catalyst has catalytic activity with anti SO₂ and anti H₂O high performance,and has good adaptability to the airspeed.The results were as follows:1)By further analysis found that when cerium and manganese quality ratio is 40%,calcination temperature is 400?,Mn-Ce/ZSM-5 prepared catalyst has excellent low-temperature denitrification performance,at 100?300?in the denitrification activity remain at more than 90%.The catalyst has better space velocity adaptability,and has high denitrification activity under high NO concentration and low O₂ content,and has a certain anti SO₂ and anti H₂O capability.2)Transient response experiments showed that:during the catalytic reaction,NH₃ is involved in the reaction of adsorbed to a large number of NO is in the form of gas or a small amount of weak adsorption state in reaction,O₂ plays a crucial role in the whole reaction,to supplement the chemical adsorption of oxygen on the catalyst surface,but also can make the lattice oxygen to be added,and the O₂ can promote the adsorption of gaseous NO.3)BET and SEM characterization of different content of Ce catalyst shows:with the increase of Ce content,the catalyst surface area and pore volume decreased,the average pore size increased,the surface of the catalyst particles increased obviously and some accumulation,caused the surface physical structure of catalyst to change;XRD characterization of different content of Ce catalyst:the characteristic diffraction peaks of vector ZSM-5 decreased,indicating that its structure will be affected,and the MnO_x and CeO_x are amorphous uniformly dispersed on the surface of the catalyst and the pores.4)XPS and NO oxidation activity of different Ce content of the catalyst:with the addition of Ce,the increase of Mn₂O₄ and surface chemical adsorption oxygen content were catalyst,so as to promote the oxidation of NO to NO₂ formation rate,improve the ability of Mn-Ce/ZSM-5 denitration catalyst further.