How is the SCR denitrification catalyst technology process
Publishdate：2019-05-15 Views：42
There are many process technologies that require attention in the clean treatment of flue gas, and SCR denitrification catalysis is also a popular topic today. Of course, some people are also concerned about the SCR denitrification catalyst technology process? SCR technology uses platinum based catalysts, but its effectiveness is not satisfactory because a large amount of ammonium nitrate is produced within its catalytic activity temperature, which has now been improved.
Chemical reactions are an important theoretical basis for modern industrial processes. SCR (Selective Catalyst Reduction) denitrification technology refers to the selective reduction of NOx in flue gas to harmless nitrogen and water using reducing agents (H2, CO, NH3, etc.) within a certain temperature range (300-420 ℃) under aerobic conditions and denitrification catalysts.
The main reactions of denitrification are 4NO+4NH3+O2==4N2+6H2O (under aerobic conditions); 2NO2+4NH3+O2==3N2+6H2O (under aerobic conditions); NO+NO2+2NH3==2N2+3H2O (anaerobic conditions)
The SCR reaction mechanism is generally believed to be the Eley Rideal mechanism, which means that the SCR reaction occurs between the NH3 adsorbed by the catalyst and the gaseous or weakly adsorbed NOx, and is a rapid reaction; Due to NO accounting for about 95%, the second reaction is the main reaction for SCR denitrification, and the actual consumption of ammonia nitrogen ratio is close to 1:1.
Main side reactions: SO2+O2===SO3; NH3+SO3+H2O==(NH4) SO4; NH3+SO3+H2O==NH4HSO4; SO2+H2O===H2SO4
The denitrification catalyst is mainly V2O5/TiO2 based catalyst, which will undergo the side reaction of SO2 oxidation during denitrification; The generated ammonium bisulfate has a high viscosity, which can easily cause fly ash to deposit on the heating surface of the low-temperature section of the air preheater, causing blockage and corrosion of downstream equipment (such as air preheaters and heat exchange components) and pipelines. Therefore, it is generally required that the SO2 oxidation rate in the denitrification process be less than 1%, and the ammonia escape be less than 3ppm; In addition, the ammonia injection temperature needs to be maintained above 300 ℃ to avoid the deposition of ammonium sulfate (which has a high viscosity and adheres to the catalyst) on the catalyst, causing micropore blockage and decreased activity.
Smoke pollution and denitrification process have attracted the attention of many manufacturers. What is the current SCR denitrification catalyst technology process? A highly active and practical SCR commercial catalyst, namely titanium based V2O5 catalyst, has been applied in industrial power plants and subsequently widely used in Europe, the United States, and other regions. At present, SCR denitrification technology has high denitrification rate, good selectivity, maturity and reliability, and is widely used in power plants, industrial kilns, and other industries both domestically and internationally under strict environmental protection requirements during the 12th and 13th Five Year Plans.
There are many process technologies that require attention in the clean treatment of flue gas, and SCR denitrification catalysis is also a popular topic today. Of course, some people are also concerned about the SCR denitrification catalyst technology process? SCR technology uses platinum based catalysts, but its effectiveness is not satisfactory because a large amount of ammonium nitrate is produced within its catalytic activity temperature, which has now been improved.
Chemical reactions are an important theoretical basis for modern industrial processes. SCR (Selective Catalyst Reduction) denitrification technology refers to the selective reduction of NOx in flue gas to harmless nitrogen and water using reducing agents (H2, CO, NH3, etc.) within a certain temperature range (300-420 ℃) under aerobic conditions and denitrification catalysts.
The main reactions of denitrification are 4NO+4NH3+O2==4N2+6H2O (under aerobic conditions); 2NO2+4NH3+O2==3N2+6H2O (under aerobic conditions); NO+NO2+2NH3==2N2+3H2O (anaerobic conditions)
The SCR reaction mechanism is generally believed to be the Eley Rideal mechanism, which means that the SCR reaction occurs between the NH3 adsorbed by the catalyst and the gaseous or weakly adsorbed NOx, and is a rapid reaction; Due to NO accounting for about 95%, the second reaction is the main reaction for SCR denitrification, and the actual consumption of ammonia nitrogen ratio is close to 1:1.
Main side reactions: SO2+O2===SO3; NH3+SO3+H2O==(NH4) SO4; NH3+SO3+H2O==NH4HSO4; SO2+H2O===H2SO4
The denitrification catalyst is mainly V2O5/TiO2 based catalyst, which will undergo the side reaction of SO2 oxidation during denitrification; The generated ammonium bisulfate has a high viscosity, which can easily cause fly ash to deposit on the heating surface of the low-temperature section of the air preheater, causing blockage and corrosion of downstream equipment (such as air preheaters and heat exchange components) and pipelines. Therefore, it is generally required that the SO2 oxidation rate in the denitrification process be less than 1%, and the ammonia escape be less than 3ppm; In addition, the ammonia injection temperature needs to be maintained above 300 ℃ to avoid the deposition of ammonium sulfate (which has a high viscosity and adheres to the catalyst) on the catalyst, causing micropore blockage and decreased activity.
Smoke pollution and denitrification process have attracted the attention of many manufacturers. What is the current SCR denitrification catalyst technology process? A highly active and practical SCR commercial catalyst, namely titanium based V2O5 catalyst, has been applied in industrial power plants and subsequently widely used in Europe, the United States, and other regions. At present, SCR denitrification technology has high denitrification rate, good selectivity, maturity and reliability, and is widely used in power plants, industrial kilns, and other industries both domestically and internationally under strict environmental protection requirements during the 12th and 13th Five Year Plans.
