An Experimental Study on NOx Reduction Efficiency and NH3 Conversion Efficiency under Various Conditions of Reductant Injection on SCR and AOC

Abstract: As the environmental regulation of vehicle emission is strengthened, investigations for NOx and PM reduction strategies are popularly conducted. Two current available technologies for continuous NOx reduction onboard diesel vehicles are Selective Catalytic Reduction (SCR) using aqueous urea and lean NOx trap (LNT) catalysts. The experiments were conducted to investigate the NOx reduction performance of SCR system which can control the ratio of NO/NO2, temperature and SV(space velocity), and the model gas was used which is similar to a diesel exhaust gas. The maximum reduction efficiency is indicated when the NO:NO2 ratio is 1:1 and the SV is 30,000 h-1 in 300°C. Generally, ammonia slip from SCR reactors are rooted to incomplete conversion of NH3 over the SCR. In this research, slip was occurred in 6cases (except low SV and NO:NO2 ratio is 1:1) after SCR. Among 6 case of slip occurrence, the maximum conversion efficiency is observed when SV is 60,000 h-1 in 400°C