Plasma-Assisted Selective Catalytic Reduction for Low-Temperature Removal of NO_x and Soot Simulant

The challenge that needs to be overcome regarding the removal of nitrogen oxides (NO_x) and soot from exhaust gases is the low activity of the selective catalytic reduction of NO_x at temperatures fluctuating from 150 to 350 °C. The primary goal of this work was to enhance the conversion of NO_x and soot simulant by employing a Ag/α-Al₂O₃ catalyst coupled with dielectric barrier discharge plasma. The results demonstrated that the use of a plasma-catalyst process at low operating temperatures increased the removal of both NO_x and naphthalene (soot simulant). Moreover, the soot simulant functioned as a reducing agent for NO_x removal, but with low NO_x conversion. The high efficiency of NO_x removal required the addition of hydrocarbon fuel. In summary, the combined use of the catalyst and plasma (specific input energy, SIE ≥ 60 J/L) solved the poor removal of NO_x and soot at low operating temperatures or during temperature fluctuations in the range of 150–350 °C. Specifically, highly efficient naphthalene removal was achieved with low-temperature adsorption on the catalyst followed by the complete decomposition by the plasma-catalyst at 350 °C and SIE of 90 J/L.