| Industrial furnaces are widely used in steel,coking,non-ferrous,building materials,petrochemical,chemical,etc.Industrial furnaces and surface coating industries are the main emission sources of nitrogen oxides?NOx?and volatile organic compounds?VOCs?mixed flue gases.As a suitable treatment technology for the mixture of NOx and VOCs,low-temperature plasma?NTP?technology has had a number of industrial applications,but bottlenecks of high energy consumption and formation of secondary pollution restricts its further development and applications.The application of plasma-catalysis technology may effectively address these bottlenecks,in which the development of novel catalysts suitable for plasma system is the key.For the characteristic of full of high-energy electrons in plasma,a“pseudo photocatalytic”behavior in plasma-catalysis system was discovered and proposed,and N-type semiconductor-Mn O2 composite catalysts which possessed excellent performance for the degradation of NOx and ethyl acetate?EA?were developed,and the characteristics of synergistic elimination of NOx and EA were studied in this thesis.A positive and benefical exploration was made for the development of plasma-catalysis combined treament of flue gas pollutants.First of all,reaction pathways and mechanism of NO removal by NTP were studied via the FTIR spectra.In normal flue gas atmosphere?6%O2?,NO was mainly oxidized to NO2 by O radicals,then the generated NO2 would react with O radicals back to NO,which led to the circulation consumption of O radicals,increasing the non-functional consumption of the system as well as inhibiting the generation of O3.The reaction behaviors and products would be regulated by O2 content and input energy simultaneously.The increase of electrode temperature and the addition of flue gas component like H2O,CO,CO2 were bad for the removal of NO,while HCl were on the contrary.SO2 revealed nearly no influence.For the deep oxidation of toxic NO2,semiconductor catalysts were introduced into plasma system.N-type semiconductor catalysts could be activated to produce electron-hole pairs by the collision of high-energy electrons from plasma,leading to pseudo photocatalysis behavior in the absence of light sources.Reaction pathways of NO removal were changed that NO could be directly deep oxidized to N2O5,NO2-and NO3-.Trapping experiments showed that O2-,·OH and O3 all made contributions to the deep oxidation of NO.To further reduce the energy consumption,a functional material of single atom Ru decorated NH2-Ui O-66?NU?/Mn O2 was fabricated.Highly enhanced plasma discharge intensity and ability of NO/NO2 adsorption and activation were observed,thanks to the decoration of isolated Ru.Moreover,the formation of oxo-bridged Zr4+-O-Ru3+can facilitate the charge transfer and the continuous proceeding of reaction.Efficient decomposition and utilization of O3 could be realized by Mn O2.100%degradation of NOx was achieved by the hybrid system at only specific input energy?SIE?of 75.3 J/L,with the complete inhibition of NO2 generation.Bi2Mo O6-Mn O2?BMO-Mn?was designed for the degradation of ethyl acetate by plasma-catalysis system.The addition of BMO-Mn greatly improved discharge intensity,the utilization of O3,and the adsorption ability of EA.Furthermore,the holes?h+?produced by the activatedremoval efficiency of EA,70%selectivity of CO2 and 99%selectivity of COx at a SIE of 392 J/L were achieved.The studies of FTIR spectra determined that CH4,CH3COOH and C3H6O were the key intermediates,and the decomposition and utilization of O3 played the key role for the mineralization of by-products.Finally,synergistic degradation of NO and EA were taken into consideration.It was found that the existence of NO2 would inhibit the degradation of EA especially the mineralization of EA.To solve the aboved drawback,composite catalyst Ce@Zn Ga2O4/NU was introduced to boost EA adsorption and hydrolysis,NO2 adsorption and activation,and the yield of active radicals.100%and 96.21%removal efficiency of NO and EA,and 73.93%and 94.35%selectivity of CO2and COx were obtained at SIE of 392 J/L.The primary intermediates were quantitatively analyzed and found that the existence of NO2 would inhibit the mineralization of C3H6O,while the addition of Ce@Zn Ga2O4/NU could accelerate the generation of CH3CHO,the key intermediate of EA.Possible reaction pathways were proposed.This research proposed a novel e*activated“pseudo photocatalysis”process in plasma,which can degrade NOx and VOCs effectively.In addition,new strategies and ideas for plasma-catalysis system would be inspired by our functional catalysts,which were artfully designed from the point of enhancing discharge intensity,adsorption and activation of pollutants,etc. |
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