Study On The Preparation And Properties Of Catalysts For Simultaneous Catalytic Reduction Of NO And SO₂ In Flue Gas By CO

The technology of simultaneous desulfurization and denitrification has been paid more and more attention because of its short process,low investment and low land occupation.Simultaneous desulfurization and denitrification by gas-solid phase catalytic reduction reaction would reduce SO2 and NO into S and N2,respectively.The product element sulfur could be recovered and utilized.The nitrogen could be discharged to the atmosphere directly.This industrial route significantly reduced the complexity of the technology.So,the energy consumption and investment cost of the technique would be decreased markedly.Therefore,it is one of the most promising technologies.This paper aims at the development of carbon-based supported catalysts for catalytic reduction with simultaneous desulfurization and denitrification.A series catalysts of FeCoY/AC,CoAlCe/AC,MnCe/?-Al2O3 were prepared by incipient wetness impregnation method.The effects of various conditions on catalyst properties,such simultaneous desulfurization and denitrification reaction activity,the oxygen resistance and thermal stability,were investigated.And the corresponding physical properties were characterized by XRD,BET,SEM and H2-TPR.The pretreatment of carrier active carbon by nitric acid could effectively improve the conversion rate of desulfurization on the catalyst.When the mass ratio of HNO3 to AC is 2.5,the conversion rate of 10Fe2Y/AC catalyst reaches 90.45%which is nearly 12%higher than that of untreated one.The best catalyst sample 10Fe6Co3Y/AC was obtained by a series of examination with combined FeCoY composite metal oxide supported on active carbon.The temperature when the conversion rate of SO2 and NO was 90%of its catalytic reaction activity reached at 216 ? without oxygen.And the final conversion rate of desulfurization and denitration can reach 100%when the reaction temperature higher than about 250 ?.By comparing the activity of 10Fe6Co3Y for different carrier loads,AC has the best load effect because of its maximum specific surface area and its reducibility,which the T90%is 150 ? below the worst performing ZrO2.The best catalyst was 10Co15A12Ce/AC in the combination of CoAlCe series composite metal oxide catalyst.Its catalytic activity reaches 90%at 190 ? without oxygen.And the final conversion rate of desulfurization and denitration can reach 100%when the reaction temperature higher than about 240 ?.Catalyst life test was carried out for the sample 10Co15A12Ce/AC at 300 ? for 120 h.Experimental result expressed that conversion rate of desulfurization and denitrification maintained above 95%,indicating that the stability of the catalyst was excellent.Characterization result indicated that both FeCoY/AC and CoAlCe/AC had the spinel structure.Experiment results showed that 10Fe6Co3Y/AC and 10Co15Al2Ce/AC catalyst samples had poor oxygen resistance property.The presence of O2 would evidently decrease the reaction activity of desulfurization and denitrification reaction.The main reason maybe attributed to the competitive adsorption between O2,NO and SO2 on the surface of active carbon.The preferential reaction of O2 with CO destroys the reducing atmosphere required for the reaction,thus inhibiting the activity of the catalyst.In addition,experiment results indicated that the toxic effect of O2 on the catalyst was partially reversible.The catalytic effect of 10Mn5Ce/?-Al2O3 catalyst was the best in the denitration by catalytic oxidation in a separate.The highest conversion rate was 87.12%at 250 ?.The addition of Ce can significantly improve the denitrification activity and sulfur resistance of the catalyst.Under the conditions of this experiment,the O2 catalytic oxidation technology is not feasible for simultaneous desulfurization and denitrification.