Preparation And Properties Of Mn/cordierite Catalyst

Management and control of the emissions of nitrogen oxide has become a key factor limiting the development of cement industry.While the application of staged combustion technology and selective non-catalytic reduction could alleviate the pressures on cement enterprises brought by nitrogen oxide to some extent,low-temperature?<200^oC?selective catalytic reduction technology,which is more efficient,stable and environmentally friendly has become the research and development center considering the sustainable development of cement industry.Porous cordierite ceramics,which shows excellent thermal shock resistance,low coefficient of thermal expansion,high chemical stability and good mechanical strength,has become a perfect catalyst carrier.Firstly,solid phase synthesis method was used to prepare porous cordierite ceramics with meta-kaolin,quartz and magnesium oxide as the raw material,carbon and starch as the pore-forming agent.Then,XRD,SEM,BET and other testing methods were used to investigate how synthesis conditions including sintering temperature,type and amount of the pore-forming agent and acid treatment affect the performance of porous cordierite ceramics.The results showed that cordierite owned excellent performance when the sintering temperature was 1300^oC and the addition of carbon was 8%.In this condition,its water absorption,porosity,flexural strength and thermal expansion coefficients could reach 23.29%,37.18%,18.66MPa,2.96×10^-6/K respectively.2 hours was a perfect acid treatment time that could rich its surface pore structure and enlarge its surface area significantly.Secondly,dip-coating method was used to prepare Mn/cordierite low-temperature SCR denitration catalyst with cordierite as the carrier and silica sol as the adhesive.The results showed that the best preparation conditions was:the ratio of silica sol?ml?and catalyst?g?was 2:1,catalyst-loading was 15%and heat treatment was 300^oC.In this condition,denitration of the catalyst in 180^oC was 82.4%and the loading-firmness was above 90%.Acid treatment of cordierite could improve the denitration and loading-firmness of catalyst slightly.Thirdly,sol-gel dipping method was used to prepare Mn/cordierite SCR denitration catalyst with cordierite as the carrier.The results showed that the best preparation conditions was:5 times of dipping,and heat treatment was 500^oC.In this condition,the amount of loading-catalyst was 10.13%,denitration of the catalyst in180^oC was 78.6%and the loading-firmness was 92.5%.Acid treatment of cordierite not only increased the amount of loading-catalyst and shortened preparation period,but also assisted the dispersing of loading-catalyst on the surface which promoted its loading-firmness.With acid treatment of cordierite,the dipping time decreased to 3times while the amount of loading-catalyst increased to 13.36%.Meanwhile,denitration of the catalyst in 180^oC increased to 81.2%and the loading-firmness also increased to over 95%.Finally,Mn/cordierite SCR denitration catalyst prepared by two different methods showed similar performance on denitration and loading-firmness.However,Mn/cordierite SCR denitration catalyst prepared by dip-coating method showed better resistance to SO₂ poisoning because of the existence of silica sol,which protected MnO_x when catalyst was wrapped by it.Meanwhile,dip-coating method showed better affordability,thus owning a more feasible application prospect.