Research Of Hexanal Decomposition Based On Non-thermal Plasma Combined With Molecular Sieves Catalyst

Plasma-catalysis technology overcomes the secondary pollution problem of individual plasma and the high energy consumption problem of individual catalytic, especially the removal effiency could be increased and the energy consumption could be reduced, when plasma was combined with molecular sieves. In this paper, metal oxides supported molecular sieves were prepared by impregnation method, the removal effiency,byproducts and energy consumption of hexanal decomposition via dielectric barrier discharge plasma and plasma-catalytic decomposition hexanal via dielectric barrier discharge plasma over molecular sieve or molecular sieve catalyst was investigated.. The main results have been surnmarized as follows:(1) The decomposition of gas-phase hexanal via dielectric barrier discharge plasma was investigated. Removal effiency of hexanal increased with increasing input energy, while declined with increasing gas flow rate and initial hexanal concentration; water vapor less than 0.5% could improve the decomposition of hexanal, while more than 0.5% would suppresse the oxidation of hexanal. Based on experiment of the influence of background gas on the hexanal removal efficiency, the primary destruction pathways, the collisions of vibrationally- and electronically-excited metastable N2 species with hexanal play an important role in the reaction,besides the reactions initiated by discharge generated radicals,(2) The removal effiency and specific energy consumption of hexanal degradation were investigated by plasma combined with three molecular sieves of different structure, the adsorption capacity of different molecular sieves catalyst were discussed. The results showed that adsorption capacity was: ZSM-5> SBA-15> MCM-41, removal efficiency: SBA-15> MCM-41> ZSM-5; hexanal removal efficiency increased and specific energy consumption decreased because of zeolite introduction, and the removal efficiency and specific energy consumption were further improved after loading MnOx . The removal of hexanal included the following process: plasma oxidation, catalytic oxidation and adsorption.(3) The removal efficiency and main byproducts of plasma and combined with SBA-15 or MnOx/SBA-15 on hexanal oxidation were studied. The effect of various factors on hexanal removal efficiency was same as the results (1); compared with individual plasma, plasma combined with MnOx/SBA-15 showed higher removal efficiency and CO2 selectivity than SBA-15, SBA-15 could not decompose ozone, while MnOx/SBA-15 could decompose ozone effectively, increasing of water vapor could reduce the production of O3 and influence the CO2 selectivity, indicating that O3 played an important role on CO 2 selectivity in this reaction system. By controlling the metal loading, relative humidity, and energy density can inhibit the formation of organic by-products; the catalyst surface may generate some long-chain materials and intermediate products containing N element, and this phenomenon becoming increasingly apparent with the reaction time.