Effect of exhaust gases of Exhaust Gas Recirculation (EGR) coupling lean-burn gasoline engine on NOx purification of Lean NOx trap (LNT)

Abstract

Based on pervious experimental research on the application of Exhaust Gas Recirculation (EGR) and Lean NOx Trap (LNT) with its effects on NOx emission control and secondary development of CHEMKIN software, an integrated NOx purification chemical kinetics mechanism including NOx adsorption, NOx desorption and NOx reduction process of LNT was created based on actual exhaust gases of the lean-burn gasoline engine. The effect of exhaust gases on NOx deterioration of LNT was investigated by modifying H2, O2 and overlap phase in mechanism of NOx desorption and NOx reduction process. Research found that the inlet temperature of LNT around 300°C possesses the best NOx adsorption performance compared with 200°C and 400°C. Pt plays an import role in the process of NOx adsorption and NOx reduction. The reductive capability order of complex compound between Pt, and H2, CO and HC is Pt–H2>Pt–CO>Pt–C3H6. Both CO2 and H2O(g) could deteriorate NOx purification of LNT. The deterioration caused by H2O(g) is not significant as CO2 but harder to be regenerated. O2 could be beneficial to the NOx adsorption process, but it also could weaken the reductive atmosphere in the process of NOx desorption and NOx reduction.