Study On The Performance Of Cu-Mn Modified USY Zeolite Catalysts At Low Temperature

SCR is the most effective method to remove NO_x,and the core of this method is catalyst.Currently commercial catalyst is V₂O₃/TiO₂ or V₂O₃-WO₃/TiO₂,and the range of reaction temperature is 350?⁴50?;the arrangement is before the dust removal and desulfurization facilities with high temperature and high dust.The smoke of the gas contains a large amount of dust,SO₂ and water vapor,resulting in partial loss of activity of the catalyst,reduced catalytic efficiency and severely shortened service life.Because Cu-based zeolites have a wide active rangement,excellent N₂ selectivity and low-temperature activity,they are considered to be the most promising catalysts.Therefore,the SCR activity at low temperature of Cu/USY catalysts with different Cu loadings was studied for low-temperature flue gas after dust removal and desulfurization facilities in this paper.In order to further improve the low temperature activity and resistance of the catalyst,Mn and Ce were added to Cu/USY catalysts,and the anti-hydrothermal aging and sulfur resistance of the catalysts before and after modification were studied.Combined with BET,XRD,SEM,FT-IR and other characterization methods,the physical and chemical characteristics of the catalyst were evaluated.The specific conclusions are as follows:The SCR activity of 10Cu/USY catalyst at 100?¹80?is higher than that of other supported catalysts,showing betteractivity at low temperature.When Mn was further added,it was found that when the Mn loading was 6%,the 10 Cu-6Mn/USY catalyst had the best low-temperature activity,and the denitrification activity also increased.Hydrothermal aging results in a decrease in the efficiency of both catalysts.The reason may be that the ability of the catalyst surface to adsorb oxygen species is reduced;SO₂will cause irreversible deactivation to the catalyst,and the reason for the deactivation is that there are a large number of sulfate accumulation pores on the catalyst surface and in the pore channel.And some active ingredients react with SO₂ and lose their activity.At the same time,after hydrothermal aging and SO₂ treatment,the activity of the catalyst is more affected.The 10Cu-6Mn/USY catalyst showed better resistance to hydrothermal aging and sulfur resistance.With the increase of Cu,Mn loading,the specific surface area of the catalyst decreased,and the characteristic peak of USY zeolite was significantly weakened.It was proved that the dispersion of the metal active component on the surface of the catalyst was higher,which was beneficial to the improvement of the SCR activity of the catalyst.Obvious USY characteristic absorption peaks and Bronsted acidic point absorption peaks were observed in the FT-IR spectra,indicating that the metal-supported catalysts increase the low-temperature activity of the catalysts without destroying the basic structure of the molecular sieves.The rare earth element Ce can increase the oxygen storage capacity of the catalyst and the chemical adsorption capacity of NH₃.Ce-modified 10Cu-6Mn/USY catalyst was added in this paper.When the Ce loading is 3%,the catalyst has the best low-temperature denitrification efficiency,and its anti-hydrothermal aging and sulfur resistance properties are studied.The results show that the 10Cu-6Mn-3Ce/USY catalyst has good resistance to hydrothermal aging and resistance.