Simultaneous Removal of Nitrogen Oxides and Particulate Matters from Diesel Engine Exhaust using Dielectric Barrier Discharge and Catalysis Hybrid System

Abstract

Dielectric barrier discharge (DBD) and catalysis hybrid process was used to remove nitrogen oxides and particulate matters from diesel engine exhaust. The DBD reactor converts a part of NO into NO 2 , and then the exhaust gas containing the mixture of NO and NO 2 enters the catalytic reactor where both NO and NO 2 are reduced to N 2 . The effect of energy density (power input divided by gas flow rate) and reaction temperature on the removal of nitrogen oxides was investigated with a stationary diesel engine. The hybrid process was able to remove about 80% of the initial nitrogen oxides at an energy density of 25 J/L and 150 • C. The removal of particulate matters did not largely depend on the electrode structure, but it was a strong function of the energy density. On the basis of 80% removal efficiency, the energy yield for nitrogen oxides was 40 eV/molecule while that for particulate matters was 83 kJ/mg. The present study suggests that this kind of hybrid process can be applied to simultaneous removal of nitrogen oxides and particulate matters from diesel engine exhausts.

Plasma-Based Depollution of Exhausts: Principles, State of the Art and Future Prospects

“…Non-thermal plasma has been applied for the treatment of exhausts of varying sizes of diesel engines from small cars, heavy trucks and marines (Miessner et al, 2002;Bröer & Hammer, 2000;Mok & Huh, 2005;Mizuno, 2007;Cha et al, 2007;McAdams et al, 2008). Same technology has also tested for oil fired boilers (Park et al, 2008).…”

“…In (Yamamoto et al, 2003) the diesel particulate filter (DPF) regeneration for real diesel engine emissions at low temperatures by means of indirect or direct non-thermal plasma treatment was demonstrated. In other studies (Chae et al, 2001, Mok & Huh, 2005 corona and DBD reactors were successfully used for the removal of smoke and particulate maters from diesel engines. For the reduction of NOx from diesel engine exhausts selective catalytic reduction is used but the catalysts do not work properly at low temperatures below (200-300°C) (Penetrante et al, 1998;Bröer & Hammer, 2000;Tonkyn et al, 2003).…”

“…For the reduction of NOx from diesel engine exhausts selective catalytic reduction is used but the catalysts do not work properly at low temperatures below (200-300°C) (Penetrante et al, 1998;Bröer & Hammer, 2000;Tonkyn et al, 2003). For improvement of the reduction efficiency at lower temperatures, plasma enhanced selective catalytic reduction (PE-SCR) has been investigated (Penetrante et al, 1998;Bröer & Hammer, 2000;Tonkyn et al, 2003;Miessner et al, 2002;Mizuno 2007;Mok & Huh, 2005;Cha et al 2007;McAdams et al, 2008;Hammer et al, 1999). In PE-SCR the plasma serves for the oxidation (NO to higher nitride oxides and hydrocarbons to partially oxidized ones).…”

“…In the second experiment, the removal of particulate matter was determined to be 95 % (5-7 mg/m 3 ). NH 3 as reducing agent was used for a commercial diesel engine from a used truck (Mok & Huh, 2005). Part of the diesel exhaust (10 sl/min) at no load condition with 180 ppm NOx and around 0.6 mg/m 3 particulate matters was introduced to the reactor system where monolithic V 2 O 5 /TiO 2 catalyst was placed downstream of the reactor.…”

“…At 200 °C, the reduction was above 65 % already without plasma. Same system was also used for the removal of PM and it was possible to remove 50 % and 80 % of PM at SIE of 20 and 40 J/sl respectively (Mok and Huh, 2005). Up to 85 % of NOx reduction with 2 % of fuel penalty has also been achieved with similar dielectric-barrier discharge/urea-SCR hybrid system applied to VW Passat TDI engine exhaust (cold start and urban driving condition) (Hammer, 2002).…”