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Since the Euro VI/6 regulation came into force in 2013/2014, most of the Diesel applications are equipped with both selective catalytic reduction (SCR) systems and Diesel particulate filters (DPF). On the one hand, SCR requires ammonia for the reduction of nitrogen oxides (NOx) created during the combustion process. An aqueous urea solution (AUS) containing 32.5% wt. urea, such as AdBlue® is injected into the hot exhaust gas upstream of the SCR catalyst to produce ammonia for NOx reduction. On the other hand, DPF demonstrates very high particle filtration efficiency, but requires to be periodically regenerated at high temperature to burn off accumulated soot. The regeneration temperature and duration can be significantly lowered by using fuel additives (fuel-borne catalyst or FBC) or by washcoating a catalyst into the DPF (catalyzed DPF or cDPF).

Diesel Exhaust Fluid (DEF) like Adblue® is a urea/water solution injected upstream from the SCR catalyst. Urea decomposes into ammonia (NH3) which acts as reducing agent in the de-NOx reaction process. However, incomplete decomposition of urea can lead to unwanted deposits formation, thereby resulting into backpressure increase, loss of NOx reduction efficiency, and durability issues. The phenomenon is aggravated at low temperatures and can lead to restriction or stop of DEF injection below certain exhaust temperatures. This paper focuses on the influence of the additivation of DEF on deposits formation in a passenger car close-coupled SCR on filter Diesel exhaust line installed in a laboratory flow bench test. The behavior of two different additivated DEF was compared to Adblue® in terms of deposits formation on the mixer and SCRF canning at different temperatures comprised between 240°C and 165°C, and different air flows.

The lifetime of the new technologies of after-treatment devices is influenced by the composition of engine oil, making it necessary to study the compatibility of lubricants with these devices. These compatibility tests usually evaluate parameters such as the long-term performance of after-treatment systems, the quantity and nature of accumulated residues due to the lubricant used, back-pressure increase, etc. This paper presents a novel, non-destructive radionuclide technique based on labeling the different elements in the engine oil (e.g. zinc and calcium), that provides additional information to after-treatment system compatibility tests: on-line measurement in the after-treatment device of the accumulation of elements from oil additives, and visualization of their distribution inside the device (inlet/outlet). Most of the work presented here focuses on the accumulation of zinc and calcium from the lubricant in a Diesel Particulate Filter (DPF).