Discharge plasma treatment for NOx reduction from diesel engine exhaust:: A laboratory investigation

A detailed study on the removal of oxides of nitrogen (NO.) 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 V2O5/TiO2 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 NOx 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.