CO ₂ Emissions Reduction through a New Multi-Functional Fluid for Simultaneous NOx and Particles Abatement 2020-01-2170

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). However, this second technique is no longer applicable when SCR catalyst is implemented on filters); continuous combustion of soot is consequently lessened.

This paper proposes to use Multi-Functional Fluids (MFFs) with regeneration additives incorporated in the AUS. This approach allows suppressing the fuel additive hardware system used in the case of FBC, and also makes possible an optimal use of the SCR catalyst on filter technology.

Physically and chemically stable formulations of efficient MFFs were developed and evaluated on engine test bench. Their efficiency to catalytically promote soot oxidation was demonstrated, during both active regeneration and loading phases (continuous regeneration). These tests also demonstrated that the MFFs keep the NOx reduction reaction at the same efficiency than with non additivated AUS.

A simulation phase showed that CO₂ reductions ranging from 0.5% to 2.9% could be achieved using MFFs. CO₂ savings vary depending on the application (passenger cars, light-duty or heavy duty vehicles, buses …), the trip characteristics and the regeneration strategies.