| Non-thermal plasma technology has been developed as an effective technology for removing volatile organic conpounds (VOCs) with low concentration. That is because it has many advantages, such as less energy consumption, high removal efficiency, and it is also simple for operation.But it may produce secondary polluttion (CO, O3, NOx), hence, non-thermal plasma-catalysis technology is used. However, the reason which causes different activities among various catalysts is not clear. Meanwhile, byproduct NOx and active species hydroxyl radicals (·OH) have rarely been studied.In this dissertation, dielectric barrier discharge (DBD) was adopted as the way of discharge; toluene was chosen as a typical VOC to carry out the experiment. The role of catalysts and factors that effects the degradation of VOCs with non-thermal plasma-catalysis technology was studied. FeOx\MnOx\CuO and CoOx was characterized to probe their different activities. Formation of byproduct NOX and its effect on toluene removal was also studied. Meanwhile, method of high performance liquid chromatography coupled with an ultraviolet detector (HPLC-UV) was developed to detect yield of OH formed in DBD reactor.1. Toluene removal efficiency(η) increased with an increase of specific input energy (SIE), so was the quantity of O3, but selectivity of carbon dioxide (SCO2) reduced; with an increase of gas flow rate and concentration of toluene,η, SCO2 as well as O3 decreased; the highestηwas obtained at the relative humidity (RH) of 20%, with a RH of 10%, the optimal SCO2 appeared, but the amount of O3 decreased with RH; when combined with catalyst, bothηand SCO2 have been greatly improved, and that of O3 lessened.2. The activity order of catalysts:FeOx>MnOx>CuOx>CoOx, MnOx was proved to have the best ability of suppressing O3 formation and increasing the SCO2; but the quantities of NOx were a little more than other catalysts.The sequence of Specific Surface Area (BET): MnOx>FeOx>CuOx>CoOx, result of Temperature Programmed Reduction (TPR) showed the reductive ability of catalysts:FeOx>MnOx>CuOx>CoOx, and which accounted for the order of activities. The species of C, N, O on the surface of catalyst was verified not only by X-ray Photoelectron Spectroscopy (XPS) but also by Fourier Transformation Infrared spectrometry (FT-IR), which could partly explain reason that catalysts inhibit the quantities of byproducts.3. It was found that quantities of NOx increased with an increase of SIE and a decrease of gas flow rate, when concentration of toluene increased, the amount of NOx also reduced. However, water vapor, which was added to the reactor, can lessen NOx quantities slightly; NOx quantities decreased greatly when catalyst used. The result of FT-IR indicated that NOx may facilitate the degradation of toluene.4. It was found that 3 h was the optimal trapping time; quantities of-OH increased from 5.9×1013 radicals/cm3 to 4.36×1014 radicals/cm3 as SIE from 140 J/L to 320 J/L. At a SIE of 320 J/L, the quantities of·OH achieved a maximum value of 2.36×1014 radicals/cm3 at RH of 20%. By changing the background gases, water vapor was identified to be the main source of·OH, small quantities of O2 (5% in volume) was favorable for the yield of OH, but the role of O2 was less important than water vapor. Argon (Ar) could enhance the yield of·OH greatly. The addition of catalyst reduced the quantity of·OH in the gas stream, however, the total quantities were almost equal to that without catalyst.
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