含氮/硫芳香族化合物的有效分离直接影响煤焦油下游加工工艺。绿色萃取剂离子液体(ILs)和低共熔溶剂(DESs)的出现为高效分离氮/硫芳香族化合物提供了新思路。煤焦油中的氮/硫化合物主要以杂环化合物的形式存在，虽然含硫量较低质量分数为0.1%~0.4%，含氮量高质量分数为0.6%~1.1%，但这些化合物结构特殊，如能分离出高纯度的化学品或化工产品单体，如咔唑、噻吩等，不仅可以有效提高这些化合物的利用价值，也会增加工厂生产效益。笔者在总结了ILs/DESs对油品中氮/硫芳香族化合物萃取分离的基础上，评述了ILs/DESs与待分离物之间存在的氢键以及π-π相互作用的影响。氢键作为ILs/DESs萃取分离的主要驱动力，对氮/硫化合物分离效率的提高尤为重要，影响氢键作用的主要因素有:质子给予体的酸度，质子接受体的电负性，萃取剂取代基的大小等。此外，待分离样品煤焦油本身不仅组成繁多，结构复杂，而且含氮/硫化合物主要以芳香杂环的形式存在，因此，萃取剂与待分离物质之间的π-π作用在萃取分离的过程中同样有着不可或缺的作用，影响π-π相互作用的因素主要有:萃取剂环共轭体系的存在与否，萃取剂取代基吸/供电子能力，萃取剂本身溶剂化作用，金属离子的π络合作用等。除了上述影响溶剂萃取分离效果的2个本质因素外，为了提高分离效率和获得更好的化学品收率，溶剂萃取分离过程的操作条件也应考虑，如:① 操作温度与氢键，π-π相互作用之间定量关系;② ILs和DESs与氮/硫化合物之间的分子间作用力以及芳烃对分离过程的影响如何降低;③ 真实油品中化合物组成结构复杂，既有脂肪烃、芳烃、还存在醚类、酯类、不同杂原子的芳香族化合物，它们之间相互作用复杂、干扰严重，ILs/DESs对真实油品中含氮/硫化合物的分离如何排除这些干扰。为此，溶剂萃取分离含硫氮化合物的工作可能需要借助数学模型，通过计算分析，筛选出更为合理的溶剂体系，以提高从煤焦油中直接分离氮/硫芳香族化合物的萃取效率。

Efficient separation of sulfur/nitrogen-containing aromatic compounds has a direct impact on the quality and performance of coal tar processing process.Being green extraction solvents,the ionic liquids (ILs) and deep eutectic solvents (DESs) provide a novel route for the extraction and separation of sulfur/nitrogen-containing aromatic compounds from coal tar.Heterocyclic compounds are the primary existing form of sulfur/nitrogen-containing compounds in coal tar.Despite the lower contents of sulfur (0.1%~0.4%) and nitrogen (0.6%~1.1%) in coal tar,the structures of the sulfur/nitrogen-containing heterocyclic compounds are complex and typical.The separation of high purity chemical monomers (eg.,carbazole and thiophene) from coal tar could effectively improve their utilization value and the production efficiency of industries.For the efficient separation of sulfur/nitrogen-containing aromatic compounds of coal tar,the extraction of nitrogen/sulfur-containing aromatic compounds from coal tar using ILs/DESs is comprehensively summarized in this paper.The influential role of hydrogen bonding and π-π interaction during the extraction is reviewed.The hydrogen bonding is a key phenomenon for improving the separation of nitrogen/sulfur-containing aromatic compounds by ILs/DESs.This intriguing hydrogen bonding depends on various factors like the proton donor’s acidity,the proton acceptor’s electronegativity,the size of substitutional groups of extraction solvent,etc.Besides the hydrogen bonding,the π-π interaction generated between the extractant solvent and the aromatic heterocycles of coal tar,which possess sulfur/nitrogen in their complex structure,also plays a pivotal role during the extraction.The occurrence of π-π interaction is governed by several key factors including the conjugation of π-bonds in extraction solvent,the electron attracting or donating ability of substituents in extraction solvent,the solvation effect of extraction solvent,and the π-complexation of metal ions.In addition to hydrogen bonding and π-π interaction,the operating conditions remarkably influence the separation efficiency and the yield of chemical monomers.For the successful extraction process by ILs/DESs,a few key concepts should be understood,including ① the quantitative relationship connecting the operating temperature,with hydrogen bonding and π-π interaction;② the in-depth knowledge about the intermolecular forces between ILs/DESs and nitrogen/sulfur-containing aromatic compounds;③ the methods to reduce the influence of aromatics on the separation process;④ the knowledge about the complex mixture of real oil,which includes the aliphatic hydrocarbons,aromatic hydrocarbons,ethers,esters and diverse heterocycle aromatic compounds,and how to reduce the influence of this complex mixture of real oil on the efficiency of ILs/DESs during the separation of sulfur/nitrogen-containing aromatic compounds from real oil.Therefore,for the better understanding of above-mentioned key concepts,it seems very essential to screen out a reasonable solvent system by calculation and analysis using a mathematical model,which would show the ways to improve the extraction efficiency of sulfur/nitrogen-containing aromatic compounds in the coal tar processing technology.

1 ILs/DESs萃取油品中含氮化合物

   1.1 ILs萃取油品中含氮化合物

   1.2 DESs萃取油品中含氮化合物

2 ILs/DESs萃取油品中含硫化合物

   2.1 ILs萃取分离油品中含硫化合物

   2.2 DESs萃取分离油品中含硫化合物

3 ILs/DESs的回收再生以及氮/硫化合物萃取效果的比较〖BT)〗

4 ILs/DESs萃取油品中含氮/硫化合物的作用机制〖BT)〗

   4.1 氢键

   4.2 π-π相互作用

   4.3 其他因素

5 展望