烷基化汽油中烃类物质含量的太赫兹时域光谱研究

Content measurement of hydrocarbons in alkylate gasoline based on terahertz time-domain spectroscopy

应用太赫兹时域光谱技术研究了烷基化汽油中烯烃在太赫兹波段的性质。以烷基化汽油中的2,4,4-三甲基戊烯为例,分析了其不同浓度在太赫兹波段产生的光谱响应。结果表明,对于烯烃含量不同的烷基化汽油,其信号中的峰强具有明显不同,并随着浓度的变化呈线性变化。利用时域谱最大值和最小值之和拟合而成的预测曲线对两种未知浓度样品进行预测,其误差均小于0.5%。同时对其不同频率下的吸收系数进行拟合与分析。根据太赫兹光谱最原始的幅值信息及其吸收系数可对其中烯烃含量进行快速定性,甚至是定量分析,为烷基化汽油中烃含量和品质的定量检测作基础。

In this work, terahertz time-domain spectroscopy（THz-TDS） was used to measure the content of hydrocarbons in alkylate gasoline as a new kind of non-destructive testing. 2,4,4-trimethyl-pentene（2,4,4-TMP）, a representative kind of olefin, was mixed in alkylate gasoline. The spectral response of the samples containing different 2,4,4-TMP in terahertz band was analyzed. The results showed that amplitude of samples had a significant change in signals and varied linearly with content of 2,4,4-TMP changed. The curves, fitting by maximum and minimum values（amplitude） of spectra, were used to predict two unknown sample concentration. As a result, the error is less than 0.5%. Meanwhile, the absorption coefficient of samples were analyzed. The research indicates that THz-TDS technique is very suitable for detection of composition and content of hydrocarbons in gasoline.