Plasma Enhanced Selective Catalytic Reduction of NOx in Diesel Exhaust: Test Bench Measurements 1999-01-3633
The potential of plasma enhanced selective catalytic reduction (PE-SCR) for Diesel-exhaust treatment at temperatures between 60 °C and 180 °C has been investigated in test bench measurements with a 1.9 liter 66 kW VW Passat TDI engine. Non-thermal plasmas were generated by pulsed electrical excitation of dielectric barrier discharge (DBD) modules each having a flow cross section of 9.5 cm2 and an electrode length of 26 cm. Monolithic V2O5-WO3/TiO2-catalysts with cell densities of 150 cpsi and 200 cpsi were used for selective catalytic reduction.
First experiments were performed with a single DBD module and a catalyst volume of 3.5 liters. For temperatures between 100 °C and 160 °C and exhaust gas flow rates below 1200 liters (STP)/min NOx-reduction rates up to 14 g/h were obtained with an energy cost of about 20 Wh/g NOx. At larger gas flow rates NOx-reduction rates decreased even at higher temperatures.
A reactor suitable for larger gas flow rates was obtained applying three DBD modules in parallel and a catalyst with a volume of 6 liters. NOx-reduction rates of 21 g/h were obtained in a test cycle beginning with a cold start and ending with an exhaust temperature of 140 °C. Energy costs were reduced to about 6.3 Wh/g NOx.