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In this study, performance of a coaxial -type packed - bed plasma reactor was investigated for simultaneous removal of NOX and diesel exhaust particles (DEP) from diesel exhaust. The plasma reactor was a concentric cylinder with a single layer of catalytic pellets (gamma-alumina or Pt -alumina) set between electrodes. Pulsed square high voltage was used. 6.0 L/min of diesel engine exhaust was used as the test gas, and space velocity was 36,000 hr-1 in this plasma reactor. The pressure drop across the reactor was about 380-540 Pa. Experiment was carried out under rich oxygen gas conditions (13- 15%) and low temperature (423K). The DEP was collected by the catalytic pellets. NO was oxidized to NO2 in the plasma and adsorbed by the catalytic pellets along with DEP. Exposing the catalysts to the pulsed plasma, collected DEP was continuously oxidized to CO2. More than 95% of DEP (including sub-nano size particles) from diesel exhaust was collected and oxidized using plasma and catalyst.

Simultaneous removal of NOx and carbon soot from diesel exhaust has been experimentally studied. We tested two types of plasma reactor (filter type and pellet type) to remove carbon soot and NOx. These reactors were driven by pulsed square high voltage. Simulated gas was used in this experiment. The filter-type plasma reactor consists of a stainless mesh tube as a high voltage electrode covered with a quartz fiber filter (or glass cloth). In the filter-type plasma reactor, about 97-98% of suspended particles were effectively collected on the surface of the filter with a weak discharge (Specific input energy value around 10J/L). The collected carbon soot was oxidized to CO2 with the SIE of about 200 J/L. A yield of generated CO2 per energy was 26mg/kJ. On the other hand, in the packed pellet-type plasma reactor, carbon soot was efficiently oxidized to CO2 compare with the filter-type plasma reactor. A yield of generated CO2 per energy was 204mg/kJ.