Preparation Of Manganese-containing Composite Catalyst And Its Low-temperature Denitrification Performance

In recent years,research on low-temperature industrial flue gas denitrification technology has attracted wide attention.The development of new low-temperature SCR catalysts is the key to this technology.The main feature of the new SCR catalyst is its wide active temperature range at low temperature and strong resistance to sulfur and water.Aiming at the rich manganese-containing soil resources in the abandoned manganese mining area,this paper studied the preparation of low-temperature SCR denitration catalyst technology and catalyst denitrification performance by using manganese-containing soil in the abandoned manganese mining area mixed with active substances,and developed an inexpensive and efficient Ce/Mn-S low-temperature SCR The denitration catalyst realizes the resource utilization of waste soil in the manganese mining area.The main research contents and achievements are as follows.The physical and chemical properties of different manganese-containing soils on manganese mining areas were studied,including manganese content and morphology,chemical composition and mineral composition.The manganese content in the manganese-containing soil is 3.46-12.3%,mainly in the form of trivalent manganese.The main composition of manganese-containing soil is SiO₂,and other impurities including Al₂O₃,Fe₂O₃ and CaO.The denitrification performance of manganese-containing soil was studied.The results show that in the abandoned manganese mining area,denitrification activity of surface slag and the river soil is high,which can reach 98%and 90.3%at 150℃,respectively,and the manganese exists in an amorphous form.The surface slag soil has a lower manganese content,but its CaO content is less and has more Mn⁴⁺and chemisorbed oxygen content.Therefore,it exhibits better catalytic activity,the denitrification rate between 150-200℃remained stable at around 98%.Doping active materials on the slag soil by impregnation method,Ce/Mn-S、Cu/Mn-S and Cr/Mn-S catalysts were prepared,and the low-temperature denitration activity and sulfur resistance of the three catalysts were investigated.Various characterization analysis found that the acidity and redox of the Ce/Mn-S catalyst were enhanced.The content of Mn⁴⁺and chemisorbed oxygen on the Ce/Mn-S catalyst increases,and the activity and nitrogen selectivity of the catalyst are improved.The denitration activity can reach 99%in the range of 125-225℃,and its anti-sulfur performance is enhanced.The denitration reaction mechanism of Ce/Mn-S and Mn-S catalysts prepared by manganese-containing soil was studied.The results show that the denitration reaction mechanism of manganese-containing soil is that NH₃ at the acid site of Lewis is converted into an amino group（-NH₂）on the catalyst surface,and then reacts with NO of the gas phase to form an intermediate product NH₂NO₂,and finally decomposes into N₂ and H₂O.The doping of metal Ce can promote the conversion of inactive nitrate and nitro compounds to NO₂ and promote the formation of amino groups（-NH₂）on the surface of the catalyst.Therefore the low-temperature SCR activity of the catalyst can be improved.