Design of Decomposition System of Toxic Substances in Exhaust Gases by Microwave-induced Plasma under Atmospheric Pressure

点击翻译按钮获取中文摘要

The following three subjects have been mainly studied in this project, and the results obtained are summarized below.1) Control of Microwave-induced Plasma in Liquid Phase and Decomposition of Organic CompoundsBehavior of microwave-induced plasmas generated from various ceramic triggers in pure water, dichloroacetic acid (DCAA) and β-naphthol aqueous solution and their abilities for decomposing these organic compounds have been investigated. The use of SiC ceramics or carbon block as a trigger in liquid phase resulted in formation of gaseous CO_2 due to partial decomposition of the trigger itself. In the case of decomposition of DCAA, La_<0.8>Sr_<0.2>CoO_3 was found to be the most suitable trigger from the viewpoints of conversion of DCAA, amounts of partial decomposition products and long-term stability as a trigger. In the case of decomposition of β-naphthol, however, FeSi was superior to other triggers, being accompanied with high ability for decomposing β-naphthol and excellent sta … More bility in liquid phase.2) Control of Microwave-induced N_2 Plasma under Atmospheric Pressure from Various Porous Ceramic Triggers and Improvement of Ability for Decomposing Dioxin-related CompoundsBehavior of microwave-induced plasmas generated from various porous ceramic triggers in Ar and N_2 gas flowing and their ability for decomposing monochlorobenzene (MCB) have been investigated. Stable nonthermal plasma could be generated from all the triggers tested in Ar flowing. However, stable plasma could be generated in N_2 flowing only when porous SIC ceramics was employed as a trigger and MCB in N_2 flowing could be decomposed almost completely under the conditions. Therefore, porous ceramics was found to be most suitable structure used as a trigger in gas phase.3)Improvement of Efficiency for Simultaneous Removal of NO_x and Diesel Particulate Matters by Microwave-induced PlasmaOxidation behavior of diesel particulate matters (DPM) and gas composition have been investigated as a function of microwave power irradiated to DPM-loaded porous SiC ceramics under 0.1% NO -10% O_2 -N_2 flowing. Additional effort has been directed to study the NO_x removal behavior by 1.0 wt% Ir/TiO_2 catalyst placed downstream from the plasma region. The amount of NO_x, formed in the downstream of the plasma region decreased markedly with increasing the microwave power, while the amounts of CO, CO_2 and H2 increased. No NO_x was detected in the effluent gas after the catalyst bet. Thus, draping of DPM by a SiC filter as well as NO, storage by suitable catalysts in the downstream and periodical irradiation of microwave to the filter are considered to be useful for simultaneous reduction of DPM and NO_x contained in the exhaust gas from diesel engine. Less