Emission Reduction with Diesel Particle Filter with SCR Coarting (SDPF)

The present paper informs about some results obtained with selective catalytic reduction (SCR) and with SDPF (a diesel particle filter (DPF) with SCR coating) on a medium duty research engine Iveco F1C. This work is a first attempt at evaluating the effects of a SDPF on non-legislated gaseous emissions and on secondary nanoparticles. Beside the limited gaseous emission components, NH3, NO2, and N2O were measured with FTIR, and the analysis of nanoparticle emissions was performed with Scanning Mobility Particle Sizer (SMPS) and condensation particle counter (CPC). The integration of functions of filtration and NOx reduction in one element of exhaust aftertreatment system offers several advantages and is widely investigated and considered as a market solution. The most important technical statements of the research are as follows:The emission behavior of SDPF after urea switch-on (SWON) concerning NOx reduction speed and NH3 peak is always fluctuating even in identical test procedures and with careful conducted conditionings.The loaded SDPF, compared with empty one, shows slower NOx reduction and higher NH3 after SWON because of use of part of NO2 for soot oxidation and consequently less NO2 availability for the deNOx reactions; the secondary nanoparticle (NP) penetration after SWON is clearly lower with the loaded trap.Both investigated systems, SDPF and 2× SCR, attain nearly the same deNOx efficiency.In worldwide heavy duty transient cycle (WHTC) with a lower level of exhaust gas temperature, SDPF causes lower deNOx values (40–45 against 75 % in European transient cycle (ETC)), but also lower NH3 emissions.
Further developments of those aftertreatment systems, concerning substrates, coatings, and reduction agent control, open further potentials of improvements.