AVS 56th International Symposium & Exhibition
    Advanced Surface Engineering Monday Sessions
       Session SE-MoA

Paper SE-MoA3
Effect of the Electrode Material in the Atmospheric Plasma Abatement of NO from Air Mixtures

Monday, November 9, 2009, 2:40 pm, Room C4

Session: Atmospheric Pressure Plasmas
Presenter: L. Bardos, Uppsala University, Sweden
Authors: L. Bardos, Uppsala University, Sweden
H. Barankova, Uppsala University, Sweden
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Protection of the environment requires more stringent limits on engine exhausts, power plant emissions and all other sources of air pollution. Different air cleaning technologies are being developed and applied for removal of pollutant gases like NO, NO2, SO2 and CO2. A very promising treatment is based on non-thermal (cold) plasmas at atmospheric pressure where dominant energy carriers are electrons and the dominant chemistry is based on formation and interactions of gaseous radicals. A widely supported method of cleaning air mixtures in the exhausts of diesels and combustion plants from NO and NO2 utilizes the Plasma Assisted Catalytic Reduction where the cold plasma is combined with the solid-state catalyst. In this method the plasma acts as an oxidation catalyst where an atomic oxygen from air oxidizes NO to NO2 and the solid-state catalysts are then capable to convert all NO2 to N2 and O2. However, in most cases it is necessary to involve also auxiliary gases, typically hydrocarbons (propene, ammonia), to make the process efficient. The present work introduces an original cold plasma system based on atmospheric hollow cathodes working in a pulsed dc regime with variable pulse voltage and repetition frequency. The system design and parameters have been optimized for the best conversion performance. It has been found that the material of electrodes can affect the oxidation efficiency of the plasma substantially. The graphite electrodes allowed the 100% conversion of NO to NO2 without any auxiliary gas. Effects of several materials on the conversion efficiency are compared and discussed.