Selective catalytic reduction technology Is for NOx in diesel exhaust emissions, a treatment process

Selective catalytic reduction technology (detergent SCR system 可控硅) Is for NOx in diesel exhaust emissions, a treatment process, namely under the action of catalyst, injection reductant ammonia or urea, reduction of NOx in the exhaust gas into N2 and H2O. With precious metals and non-noble metal catalysts. The technology has been widely used in diesel exhaust aftertreatment, by optimizing the fuel injection and combustion process, try to control the generation of particles PM inside the machine, and then formed in conversion processing under the condition of rich oxygen nitrogen oxides, immediately with detergent ( Washing powder at certain temperatures decomposition generated ammonia) The nitrogen oxide ( 氮氧化物) For selective catalytic reduction, so as to achieve the purpose of energy saving and emission reduction, the technology is the European mainstream technology route, the long-distance truck and buses almost all adopt the technology. Chinese name SCR system explain the selective catalytic reduction technology for diesel exhaust emissions NOx in diesel exhaust aftertreatment system is the basic working principle of ( See image below) : from after the exhaust turbine exhaust gas mixture tube, urea metering jet devices are installed on the mixing tube, urea solution, injection of urea hydrolysis and pyrolysis reaction at high temperatures generated after NH3, the SCR system using NH3 NOX reduction catalyst surface, get rid of N2, excess NH3 oxidation as N2, prevent leakage. In general, 100 l of fuel consumption at the same time consumes 5 l liquid urea aqueous solution. Chemical reactions are as follows: in the SCR urea hydrolysis: ( NH2) 2 co + CO2 + H2O - > 2 NH3 NOX reduction: NO + NO2 + 2 NH3 - > 2 n2 + 3 H2O NH3 oxidation: 4 NH3 o2 and n2 + 2 + 3 6 H2O in the SCR system of complicated physical and chemical reactions including: urea aqueous solution injection, atomization, evaporation, urea hydrolysis and pyrolysis gas phase chemical reactions and NOX in surface chemical reaction with NH3 in the surface of the catalyst.