Discussion on the preparation method of low-temperature SCR denitrification catalyst
Publishdate：2018-09-28 Views：16
The research and development of low-temperature SCR catalysts at home and abroad are relatively immature in terms of technology. At present, a few low-temperature SCR catalysts have appeared at home and abroad, such as MnOx/CeO2 catalysts prepared by coprecipitation method, MnOx/TiO2 catalysts prepared by sol gel or coprecipitation method, etc. Low temperature SCR catalysts often exhibit good reactivity in flue gas without SO2 and H2O. However, in practical situations, after passing through dust removal and desulfurization devices, the flue gas still contains H2O and SO2. Under these conditions, low-temperature SCR catalysts are prone to poisoning and deactivation. There are also reports of adding catalytic agents to improve their resistance to SO2 and H2O in the flue gas.
A manganese based low-temperature denitrification catalyst and its preparation method are disclosed. The steps include dissolving manganese nitrate, iron nitrate, crystalline tin tetrachloride, and cerium nitrate in water at room temperature, stirring to form a transparent solution; Step 2: Prepare ammonium carbonate solution, add it dropwise to the solution prepared in step 2, heat and stir to obtain the slurry; Step 3: Immerse the slurry with ultrasound, then filter it to obtain a filter cake, and then clean it with deionized water; Step 4: Dry and calcine the filter cake to obtain a manganese based low-temperature denitrification catalyst, MnFeSnCeOx catalyst. The catalyst has a purification efficiency of 71-100 percent for NOx under 300ppm SO2 conditions in the range of 80-250 ℃. A low-temperature catalyst was prepared using attapulgite as the carrier, manganese as the main catalyst, and the addition of co catalyst components K, Mg, or Ce oxides. Under SO2 conditions of 0-800ppm, the removal rate of NOx was relatively high. However, the catalysts prepared above are only applicable to the denitrification effect in the presence of only SO2, and do not involve the denitrification effect of catalysts in the presence of both SO2 and H2O.
A preparation method for a low-temperature SCR denitrification catalyst has been disclosed, which involves dissolving ammonium metavanadate, transition metal salts, and titanium tungsten powder in water, and preparing the low-temperature SCR denitrification catalyst through drying and calcination. The catalyst prepared by the invention has a NOx removal rate of 38-72% at 150-250 ℃ under conditions of 300ppm SO2 and 10% water vapor content, and can maintain good nitrogen oxide removal rate and water and sulfur resistance performance between 150-250 ℃. However, the catalyst prepared by the invention belongs to the vanadium tungsten series catalyst, and ammonium metavanadate is calcined to become V2O5. V2O5 is a highly toxic substance that can cause serious pollution during production and use.
A low-temperature catalyst was prepared using honeycomb ceramics, activated carbon, or molecular sieves as carriers, manganese molybdenum nickel composite oxides as active ingredients, and copper chromium cerium oxides or several other oxides as co catalysts. Under the conditions of 300ppm SO2 and 6% water vapor content, the NOx removal rate was above 80% at 150 ℃. However, when the above catalysts contain both SO2 and water, their denitrification activity is not high enough, and the low-temperature temperature range with a denitrification rate greater than 90% is narrow, which limits their application.
Both types of SCR catalysts are suitable for various fuels such as coal, gas, biomass, and garbage, and can be widely used in industrial boilers, glass ceramic furnaces, cement furnaces, steel metallurgical sintering furnaces, coking, nitric acid production, and cracking equipment in petrochemical systems.
Low temperature SCR denitrification catalyst
The research and development of low-temperature SCR catalysts at home and abroad are relatively immature in terms of technology. At present, a few low-temperature SCR catalysts have appeared at home and abroad, such as MnOx/CeO2 catalysts prepared by coprecipitation method, MnOx/TiO2 catalysts prepared by sol gel or coprecipitation method, etc. Low temperature SCR catalysts often exhibit good reactivity in flue gas without SO2 and H2O. However, in practical situations, after passing through dust removal and desulfurization devices, the flue gas still contains H2O and SO2. Under these conditions, low-temperature SCR catalysts are prone to poisoning and deactivation. There are also reports of adding catalytic agents to improve their resistance to SO2 and H2O in the flue gas.
A manganese based low-temperature denitrification catalyst and its preparation method are disclosed. The steps include dissolving manganese nitrate, iron nitrate, crystalline tin tetrachloride, and cerium nitrate in water at room temperature, stirring to form a transparent solution; Step 2: Prepare ammonium carbonate solution, add it dropwise to the solution prepared in step 2, heat and stir to obtain the slurry; Step 3: Immerse the slurry with ultrasound, then filter it to obtain a filter cake, and then clean it with deionized water; Step 4: Dry and calcine the filter cake to obtain a manganese based low-temperature denitrification catalyst, MnFeSnCeOx catalyst. The catalyst has a purification efficiency of 71-100 percent for NOx under 300ppm SO2 conditions in the range of 80-250 ℃. A low-temperature catalyst was prepared using attapulgite as the carrier, manganese as the main catalyst, and the addition of co catalyst components K, Mg, or Ce oxides. Under SO2 conditions of 0-800ppm, the removal rate of NOx was relatively high. However, the catalysts prepared above are only applicable to the denitrification effect in the presence of only SO2, and do not involve the denitrification effect of catalysts in the presence of both SO2 and H2O.
A preparation method for a low-temperature SCR denitrification catalyst has been disclosed, which involves dissolving ammonium metavanadate, transition metal salts, and titanium tungsten powder in water, and preparing the low-temperature SCR denitrification catalyst through drying and calcination. The catalyst prepared by the invention has a NOx removal rate of 38-72% at 150-250 ℃ under conditions of 300ppm SO2 and 10% water vapor content, and can maintain good nitrogen oxide removal rate and water and sulfur resistance performance between 150-250 ℃. However, the catalyst prepared by the invention belongs to the vanadium tungsten series catalyst, and ammonium metavanadate is calcined to become V2O5. V2O5 is a highly toxic substance that can cause serious pollution during production and use.
A low-temperature catalyst was prepared using honeycomb ceramics, activated carbon, or molecular sieves as carriers, manganese molybdenum nickel composite oxides as active ingredients, and copper chromium cerium oxides or several other oxides as co catalysts. Under the conditions of 300ppm SO2 and 6% water vapor content, the NOx removal rate was above 80% at 150 ℃. However, when the above catalysts contain both SO2 and water, their denitrification activity is not high enough, and the low-temperature temperature range with a denitrification rate greater than 90% is narrow, which limits their application.
Both types of SCR catalysts are suitable for various fuels such as coal, gas, biomass, and garbage, and can be widely used in industrial boilers, glass ceramic furnaces, cement furnaces, steel metallurgical sintering furnaces, coking, nitric acid production, and cracking equipment in petrochemical systems.
Low temperature SCR denitrification catalyst
