Study Of Catalyst For Selective Reduction Of NO At Low-temperature With NH₃

NOx is a general term for nitrogen oxides, usually including NO and NO2, etc. The main source of the NOx in the atmosphere comes from natural and human activities, NOx generated by human activities is about 100 million tons per year, which caused by burning. But 90% of the NOx in flue gas is NO. NOx has a direct or indirect influence to the atmosphere and human living environment. Such as destruction of the ozone layer, acid rain, forest reduce and so on. Some scholars believe that NOx does more harm to the human health and environmental than SOx.The text supported MnOx/zeolite catalyts prepared by low temperature impregnation. Physical and chemical properties of the catalysts were characterized by SEM, TG-DSC-MS, XRD, H2-TPR and NH3-TPD methods. The activities of catalyst were investigated in detail from factors of vector, loading, cocatalyst. The main results were summarized as follows:(1)The 5% content of the MnOx/zeolite prepared by low-temperature impregnation method was prepared, which zeolites contains HY, NaY, NH4Y, REY, RPSY, Hβ, HZSM-5, HTS. It was found that zeolites influenced the catalyst activity, and the catalysts carried by ZRP, Hβand REY has the best Low temperature activity. The NO conversion reaches almost 85% at 210-220℃. The catalysts carried by NaY, NH4Y and HTS have the worst conversion. In our test, Mn/RE Y and Mn/Hβhave better activity when added SO2.(2)MnOx supported on the Hβ. By the activity test system, It found that almost all the metal additives improve the catalyst activity. And the Rare-earth mental acts the better activity than the other catalysts, for example, 0.1La5%Mn/REY catalysts has an NO conversion of 85% in 144℃, and the conversion of 95% in 161℃.(3) MnOx supported on the REY, catalysts which added Cu cocatalyst have better activities even though SO2 was added. The catalyst which molar ratio Cu/Mn is 0.6 has the best activities when 100μL/L SO2 was added, T85 is 137℃, and T95 is 154℃. The catalyst which molar ratio Cu/Mn greater than 0.4 has the best activities when 0.01mL/min H2O was added. Cu-Mn/REY catalysts have better activity when added SO2 and H2O at the same time.