中试规模下微等离子体对甲苯的降解性能研究

为了实现高效、低能耗降解大流量下低浓度的污染物,在中试规模常温常压下采用了微等离子体技术对大流量的甲苯废气进行处理。从气体流量、甲苯浓度、相对湿度、微等离子体反应器输入能量密度等方面,对甲苯降解性能进行评价;采用气相色谱、质谱和红外光谱仪对降解反应产物进行分析,探讨了微等离子体降解甲苯的机理及反应途径。结果表明,在废气流量为100 Nm³·h^-1,甲苯浓度为50 ppm,相对湿度为1%~3%,输入能量密度为30 J·L^-1时,微等离子体对甲苯的降解率达到74.4%。甲苯分子在微等离子体中的降解主要是通过高能电子轰击和活性物种氧化,甲基C-H键易受到高能电子的轰击生成一系列含氧有机中间产物,醛类、酚类、醇类、羧酸类、以及带苯环的衍生物等。

Study on Degradation of Toluene by Micro-plasma in Pilot Scale

In order to achieve high-efficiency and low-energy degradation of low-concentration pollutants at high flow rate, this study intends to use micro-plasma technology to treat large volume of toluene exhaust gas under normal temperature and atmospheric pressure in pilot scale. The toluene degradation performance was evaluated from toluene concentration, relative humidity, reactor input energy density, and exhaust gas flow rate. The degradation reaction products were analyzed by gas chromatography, mass spectrometry, and infrared spectroscopy. On the basis of the analytic results of GC-MS, the reaction pathway and mechanism of destruction of toluene in the micro-plasma system were discussed. The results showed that under the exhaust flow rate of 100 Nm³·h^-1, the input energy of 30 J·L^-1, and the relative humidity of 1%~3%, the degradation rate of toluene by micro-plasma was up to 74.4% with the toluene concentration of 50 ppm. The degradation of toluene in micro-plasmas is mainly through high-energy electron bombardment and active species oxidation. Methyl C-H bonds are easily bombarded by high-energy electrons to produce a series of organic oxygen-containing intermediates, such as aldehydes, phenols, alcohols, carboxylic acids, and derivatives with benzene rings.