Abstract
For EURO V most of the exhaust aftertreatment systems include a DOC-DPF system to fulfil the legislation regarding CO, HC and particles. For EURO VI applications an active NOx aftertreatment system will be necessary and the fuel economy will be also more in focus. One of the possible technologies for the reduction of nitrogen oxides in lean exhaust gas is the NOx storage catalyst (LNT) which is utilized in the current BIN 5 diesel system from VW. For heavier applications urea- SCR is the preferred technology to fulfil NOx legislation limits. Furthermore most of the EURO VI applications will show lower exhaust gas temperatures in the NEDC cycle compared to EURO V applications and therefore the requirements for the exhaust aftertreatment systems will rise.
In this paper different layouts for the aftertreatment system will be evaluated and discussed regarding NOx, CO, and HC. Main focus is on the NOx storage catalyst (LNT). Basically the system NSC-cDPF without DOC will be investigated regarding the different challenges, e.g the temperature profiles in the NEDC cycle and the requests regarding desulphation and thermal stability. The results will be discussed on the bases of model gas and engine bench measurements.
Beside the reduction of total NOx, both SCR and LNT technologies are very effective in reducing NO2.
Keywords: Diesel EURO VI, NOx Storage Catalyst, LNT, SCR, NO2