真空紫外光解乙苯废气的工艺特性及转化机制研究

Conversion characteristics and mechanism analysis of gaseous ethylbenzene degraded by vacuum ultraviolet photodecomposition

采用真空紫外光（UV185mm）处理含乙苯的模拟废气，考察了工艺参数对乙苯转化效率的影响，探讨了影响苯系物和环状烯烃转化的主要因素，并采用多参数动力学模型拟合了不同相对湿度下乙苯转化的过程，初步研究了该工艺对混合废气的转化特性和不同组分间转化的增抑效应。结果表明，直接光解和光解产生的O3、HO·等活性物质在乙苯的转化过程中起到了主要的作用；在乙苯等苯系物转化中，HO·氧化起主导作用，而在α-蒎烯等环状烯烃转化中，O3氧化起主导作用，因而当反应介质的相对湿度增加时，乙苯的转化率将有一定提高；乙苯初始质量浓度为0-200mg／m^3时，其光转化过程符合一级动力学模型，R^2在0．97以上；乙苯光解的主要初步产物为乙酰苯、苯甲酸、邻甲基酚等。经过进一步光解可使苯环开环，生成乙二酸、丁二酸等小分子酸，最终转化为CO2、H2O等无机物；混合废气的光解转化相互影响分析表明，乙苯的加入对α-蒎烯的转化没有抑制作用，甚至低浓度乙苯的加入还能促进α-蒎烯的转化；而在乙苯光饵体系中引入α-蒎烯会对其转化产生抑制。

Vacuum ultraviolet technology was applied to convert ethylbenzene containing simulated exhaust gas. The effects of process parameters on ethylbenzene conversion were investigated and the main factors influencing the benzene series conversion was discussed. The multiple-parameter dynamic model was used to simulate the ethylbenzene conversion process under different relative humidity. The conversion characteristics of gaseous mixture and the inhibition effect between various components were also studied. Results showed that the direct photolysis,photolytic products （HO · and O3） played the key role of ethylbenzene and α-pinene conversion,in which HO · oxidation was the dominant mechanism of ethylbenzene conversion while O3 oxidation play the leading role of α-pinene conversion. Ethylbenzene achieved the better conversion rate under higher relative humidity. The dynamic conversion data could be well fitted by first order kinetics model under the initial concentration of 0-200 mg/m3 （R^2 〉0.97）. The primary photolytic products of ethylbenzene was acetyl benzene, benzoic acid, O-cresol, further photolysis could make benzene ring open and produce oxalic acid, succinic acid and other small molecule acid and finally translate these organics into CO2, H2O and other inorganic substances. Photodecomposition of gaseous mixture （ethylbenzen and α-pinene） showed that the appearance of ethylbenzen had no inhibitory effect on α-pinene conversion and lower concentrate ethylbenzen could promote the conversion of α-pinene,while the inhibitory effect of α-pinene on ethylbenzen photodecomposition was more obvious.