Discharge Plasma Treatment for ${NO}_x$ Reduction from Diesel Engine Exhaust: A Laboratory Investigation

Abstract

A detailed study on the removal of oxides of nitrogen $({NO}_x)$ with and without the presence of carbonaceous soot in a stationary diesel engine exhaust was carried out using pulsed electrical discharges/catalyst/adsorbent processes. The processes were separately studied first and then the cascaded processes namely plasma-catalyst and plasma-adsorbent were examined. To investigate the effect of carbonaceous soot on the plasma treatment process, the filtered and unfiltered exhaust was treated by plasma separately. In the cascaded plasma-catalyst process, the plasma treating filtered exhaust was cascaded with a reduction catalyst $V_2O_3$/$TiO_2$ using ammonia as reducing agent and in the cascaded plasma-adsorbent process, the plasma treating unfiltered (raw) exhaust was cascaded with adsorbents (MS-13X/Activated alumina/Activated charcoal). The enhanced $({NO}_x)$ removal efficiency of plasma process in the presence of soot is identified, possible pathways are summarized and the results of the cascaded processes are discussed in detail