煤焦油的拉曼光谱表征和组分识别

Characterization of coal tar and components identification by Raman spectroscopy

用355 nm激光作为激发光源检测了煤焦油常温拉曼光谱;应用两种量子化学计算程序(Gaussian-DFT和ADF)模拟了占总量1%以上的15种煤焦油组分的拉曼光谱,模拟结果与实验光谱能较好匹配,并对振动模式进行了归属分析。研究表明,煤焦油组分主要由共轭六元环构成,其拉曼光谱特征谱带主要在1 660、1 420和1 265 cm-1附近,当共轭六元环成链式结构时,1 420 cm-1谱带特征明显;五元环嵌入共轭六元环链式结构会导致其拉曼光谱在1 265和1 660 cm-1谱带相对强度增大;五元环、杂原子基团和甲基侧链依附在共轭六元环上,则对组分的拉曼光谱影响不显著。

Raman spectrum of coal tar was measured by using 355 nm laser at ambient temperature. Simultaneously, Raman spectra of 15 components which each weighted more than 1% in coal tar were also simulated. The calculated results are in good agreement with the experimental ones and the vibrations of Raman spectra of coal tar are assigned. The results indicate that the most components of coal tar are mainly composed of six-membered ring type hydrocarbons with the characteristic bands at 1 660 , 1 420 and 1 265 cm-1 , which are attributed to the C-C stretching vibrations. When the hydrocarbons connect each other in a resonant mode and chain-like structure, 1 420 cm-1 band is demonstrated significantly. When the hydrocarbons are embedded by the five-member ring type hydrocarbons, the intensity of 1 265 and 1 660 cm-1 band increases significantly. There is little effect on the spectra of the component molecule provided the five-membered ring type hydrocarbons, heteroatom groups and methyl are only connected at the edge of the component molecule.