Research On Preparation And DeNOx Characteristics Of Modified Biochar Materials Based On Industrial Solid Waste

The NOx emitted by industrial production is harmful to the ecological environment.At present,the most effective NOx control method is selective catalytic reduction（SCR）;On the other hand,industrial solid waste contains many commonly used substances for preparing SCR catalysts（Al₂O₃,Si O₂,Fe₂O₃ etc.）,if it can be used to prepare SCR catalysts,it can not only reduce the pollution of soil,rivers and atmosphere caused by its massive emissions,but also decrease the preparation cost of SCR catalysts,which has important practical significance.Based on this,this article uses several typical industrial solid wastes in the electric power,metallurgy and chemical industries:fly ash,steel slag,blast furnace slag,fluid catalytic cracking（FCC）waste catalysts and agricultural solid waste corn cobs as raw materials.SCR denitrification catalyst,studied the synergistic denitrification performance of industrial solid waste and biochar,and used XRD,BET,FTIR,SEM and EDS characterization methods to deeply explore the influence of the physical and chemical properties of the catalyst on its denitrification performance.First,pre-calcining industrial solid waste and pyrolysis of corn cob to prepare biochar,and the effect of pyrolysis temperature on the denitration performance of biochar and the effect of calcination temperature on the denitration performance of industrial solid waste was investigated.The results demonstrate that the biochar prepared at a pyrolysis temperature of 600°C has the best denitrification activity and economy.The calcination temperature is 650°C treated steel slag,450°C treated blast furnace slag,unsecured FCC waste catalyst and fly ash denitration activity highest.Secondly,the selected biochar and industrial solid waste were mechanically mixed in different proportions to prepare a composite catalyst,and a control experiment of biochar,industrial solid waste and composite catalyst was set up.Experiments have found that when the mixing ratio of biochar and industrial solid waste is 2:1,the prepared composite catalyst can maximize the utilization of industrial solid waste while ensuring the denitration efficiency.At the same time,a composite catalyst was prepared by co-pyrolysis of corn cob and industrial solid waste.The effects of blending ratio,co-pyrolysis temperature and industrial solid waste type on its denitration performance were studied.It was found that steel slag has excellent catalytic pyrolysis ability.Using corncob and steel slag as raw materials（corncob/steel slag=3:1）,the composite catalyst prepared by co-pyrolysis at 400°C has the highest denitration efficiency.In addition,the above-mentioned composite catalyst（SFCC+CB）with better denitration performance was selected as the research object,and the influence of different reaction conditions on its denitration activity was investigated.Research shows that when the NO concentration is 400ppm,the NH₃/NO ratio is 1,the O₂ content is 5%,and the reaction temperature is 100°C,the denitration efficiency of the composite catalyst is the highest 47.04%.By studying the kinetic characteristics of denitration reaction of the SFCC+CB catalyst,the reaction orders of NO,NH₃ and O₂ are 0.611,0.548 and 0.48,respectively.The appearance of the SFCC+PCB catalyst is calculated according to the Arrhenius formula.The activation energy of the reaction is87.46k J/mol,which provides a theoretical basis for industrial applications.Finally,in order to further enhance the denitrification activity of the composite catalyst,industrial solid waste and biochar prepared by phosphoric acid activated corn cob were blended as a carrier,and the transition metal Mn was loaded to prepare the Mn modified SCR catalyst.The effect of preparation conditions on the denitration performance of the Mn modified composite catalyst was systematically investigated,and the space velocity resistance and service life of the Mn modified composite catalyst were checked.The results show that when the carrier is SFCC+PCB,the Mn loading is18%,the calcination time is 3h,and the calcination temperature is 500°C,the Mn modified composite catalyst has the highest denitration efficiency.The reaction temperature is 260°C and the space velocity is 9200h^-1,denitration efficiency can reach95.95%,and after 11 hours of continuous reaction,it can still maintain the denitration efficiency of more than 95%,with good active persistence and stability.