Study On Heat Treatment And Forming Process Of Supported CO-SCR Denitrification Catalyst

Nitrogen oxide（NO_x）is one of the main pollution sources of air,mainly exists in automobile exhaust and factory smoke,which has great harm to the environment and human body.Selective catalytic reduction（SCR）is the most promising NO_x removal technology.At present,SCR catalytic denitration reaction commonly used reductants are NH₃,H₂,HC and CO.Among them,CO,as a reducing gas,can generate CO₂and N₂ by removing NO,and avoid ammonia escape,pipeline corrosion and other problems,which can save costs at the same time.Therefore,it has attracted the attention of researchers around the world.Vermiculite（VMT）,as a kind of natural mineral resource,generates two-dimensional layered structure after high-temperature expansion,with large specific surface area,and has broad application prospect as catalyst carrier.This paper mainly studied the heat treatment and forming process of vermiculite supported CuCeO_x catalyst,the details are as follows:（1）Heat treatment of supported CuCeO_x/VMT denitrification catalyst in CO-SCRThe precursors of CuCeO_x/VMT were prepared by coprecipitation-assisted constant volume impregnation method using two-dimensional natural mineral vermiculite as carrier.Four CuCeO_x/VMT catalysts were prepared by muffle furnace direct calcination,sand bath calcination,carbon bath calcination and tube furnace nitrogen protected calcination,and the denitrification performance of CO-SCR was tested.The uniform dispersion of active components was found by morphology characterization,and the reason for the synergistic effect of Cu and Ce was analyzed.XRD,BET,XPS,Raman and other characterization showed that the presence of Ce³⁺and Cu⁺improved the denitration performance at low temperature.The mechanism of CuCeO_x/VMT（M）catalyst for nitrogen oxides removal at low temperature was discussed and the reaction path was speculated.The results show that CuCeO_x/VMT（M）has excellent specific surface area（110.6 m²/g）,abundant oxygen vacancy and low temperature CO-SCR properties,which conform to the E-R reaction mechanism.At 250 ^oC,the conversion rate of NO could reach 94.5%.（2）Study on CuCeO_x/VMT monolithic honeycomb catalystThree kinds of honeycomb mullite monolithic catalysts were prepared by solution impregnation（A）,precursor coating（B）and powder coating（C）after pretreatment with honeycomb mullite as carrier.The performance of the three monolithic catalysts was compared,and it was found that the catalyst（B）coated with the precursor showed excellent low temperature performance.SEM,TEM and HRTEM were used to observe the uniform dispersion morphology of the three monolithic catalysts.XRD,BET,XPS and Raman were used to analyze the active components on the surface of three monolithic catalysts.The results showed that the active components of the CuCeO_x/VMT（M）monolithic catalyst prepared by the precursor coating were evenly dispersed and had excellent specific surface area.It was also found that the GHSV=2666.6 h^-1at 250 ^oC and the conversion rate of NO was 92%when the loading capacity was 148.2 kg/m³.