紫外光谱法分析煤直接液化油族组成

煤液化油组成的测定方法以色谱法为主，但由于样品沸程长，组分性质不均一，色谱法无法实现简便快速地对液化油族组分进行定性/定量。为建立一种快速准确定量煤液化油中的酚类化合物、芳烃、脂肪烃的分析方法，本文选取具有代表性组成的煤液化油180～200 ℃馏分为研究对象，筛选了环己烷、乙醇、氢氧化钠-乙醇(50 Wt%，简称碱醇溶剂)三种分离溶剂。通过对煤液化油样品在200～400 nm波长间的特征吸收峰分析，发现碱醇溶剂可使芳烃化合物对酚类化合物的干扰减少到最小，可以有效避免吸收峰重叠问题。在此基础上，进一步对比分析了苯酚，间甲酚，邻甲酚，对甲酚等标准化合物与液化油酚类混合物在碱醇溶液中紫外吸收的标准曲线，以定量样品组成。选择间甲酚为标准化合物，根据其在290 nm处的标准曲线，得到煤液化油中酚类化合物的总量为32.14%，测定结果与宏量样品分离、称重、物料平衡后结果基本一致。在得到酚类化合物含量之后，以四氢萘为标准物，获得液化油中芳烃的总量为44.91%，脂肪烃的含量为22.95%。为确定方法的准确性，油样分别加入不同量的间甲酚和四氢萘标准物，酚的加标回收率为104.3～110.75%，芳香烃的加标回收率在84.3～91.75%。综上表明：利用紫外光谱法，以碱醇溶剂排除芳烃对酚吸收的影响，能够快速测定煤液化油中酚类和芳香烃的含量，脂肪烃的含量可差减得到。

A Quick Quantitative Analysis for Group Composition of Coal Liquefaction Oil by Ultraviolet Spectroscopy

Gas chromatography is now the primary analysis method for the coal liquefaction oil. However, a simple and rapid quantification/qualification of the coal liquefaction oil can hardly be realized, because the coal liquefaction oil is in a heterogeneous state with a long boiling range. The aim of this study was to establish a rapid and accurate method for the quantification of phenolic compounds, aromatics and aliphatic hydrocarbons in coal liquefaction oil. A representative composition of coal liquefaction light oil, i.e. the distillate fractions of the boiling point range 180～200 ℃, was chosen as the investigated object. The characteristic absorption peaks of the samples in the UV spectra (200～400 nm) were examined, using three kinds of solvents, cyclohexane, ethanol, 50 Wt% NaOH/ethanol mixture. Among them, the mixture solvent provided the best performance, where the aromatics interfered minimally with the quantification of phenolic compounds by avoiding the peak overlapping problem. By comparison of the UV absorption standard curves between the standard compounds (phenol, m-cresol, p-cresol and o-cresol) and the phenolic mixtures in coal liquefaction oil, m-cresol was selected for the quantification of phenolic compounds in coal liquefaction oil. The content of phenolic compounds was determined to be 32.14% according to the calibration curve of m-cresol at 290 nm, and this result is largely consistent with that determined by weighing after separation. Based on UV and GC analysis of the dephenolized oil, the standard curve of tetrahydronaphthalene at 266 nm was used for the quantification of aromatic hydrocarbons in coal liquefaction oil. The contents of aromatic and aliphatic hydrocarbons were determined to be 44.91% and 22.95%, respectively. To verify the accuracy of the method, recovery of added standards in the oil samples was determined and found to be 104.3%～110.75% and 84.3%～91.75% for phenolic compounds and aromatics, respectively. These results indicate that the contents of phenolic compounds and aromatics can be determined simultaneously with the UV standard curves of m-cresol and tetrahydronaphthalene, respectively, and the aliphatic compounds can be determined by difference.