Proposal of simultaneous decomposition of diesel particulate material and nitric oxide using dielectric barrier discharge

Summary form only given. Thermodynamically non-equilibrium gas discharges, such as packed-bed discharge, corona discharge and dielectric barrier discharge (DBD), have been investigated to decompose the emissions of diesel particulate material (DPM) and nitric oxide (NOx) from diesel engines and other combustion processes. However, the decomposition efficiency is still low because DPM and NOx are exhausted in very small concentrations. Therefore, in order to extract the potential of these discharges for the decomposition, condensation or localization of these hazardous materials is prerequisite. Recently, we have proposed a new decomposition technique for environmentally hazardous materials with very low concentration, and achieved a successful decomposition of volatile organic compounds. This is based on the combination of a DBD with condensation/localization using honeycomb-shaped adsorbents. This combination does not spoil the high gas flow rate, and the DBD can easily generate non-equilibrium plasmas on a large discharge space. In this paper, we demonstrate this technique for simultaneous decomposition of DPM and NOx exhausted from a diesel engine. DPM and NOx are collected in a reactor using an electrostatic precipitation and a honeycomb-shaped adsorbent, respectively. After the sufficient collection, the DBD is generated in the closed space to condense the DPM and NOx, and decomposes these simultaneously. In preliminary experiments, over 60% of DPM was collected on the electrodes at DC 2 kV, and cyclic adsorption/desorption of NOx was achieved by the temperature control using the DBD. The NOx decomposition using the DBD in the existence of DPM was obtained to be about two times larger than that without DPM. DPM and NOx act as the oxidant and reductant, respectively, and are decomposed simultaneously and effectively by the DBD. It is considered that this technique is the most suitable for the decomposition of small concentration hazardous materials