Abstract:

In order to maximize the utilization value of various components in coal-based liquids, the research progress of highly efficient extraction and separation of complex components from coal-based liquids by ionic liquids and deep eutectic solvents is reviewed. Firstly, the properties and classification of ionic liquids and deep eutectic solvents are briefly introduced. Secondly, according to the target compounds, the extractive separation are divided into four aspects: phenol extraction from coal-based liquids, extractive desulfurization of fuel oils, extractive denitrification of fuel oils, and the separation of aromatics and aliphatic hydrocarbons. The analysis shows that ionic liquids and deep eutectic solvents have good phenol extraction effect for actual coal-based liquids, and can separate most phenolic compounds. When fuel oils are extracted and desulfurized, ionic liquids and deep eutectic solvents are also effective for actual coal-based liquids, but the desulfurization rate is not high for one time operation and it takes 3 to 5 repeated extractions to obtain the desired results. The denitrification efficiency is not high and this is because the basic and non-basic nitrogen-containing compounds in the fuel oils are difficult to be extracted and separated by the same ionic liquid or deep eutectic solvent at one time. Most ionic liquids and eutectic solvents do not achieve the ideal partition coefficients and selectivity when separating aromatics and aliphatic hydrocarbons, and cannot be used for separation of aromatics and aliphatic hydrocarbons from coal-based liquids. Differences in intermolecular interactions such as hydrogen bonding, π-π, CH-π, and Van Der Waals etc. are the main reasons for the different separation of typical components in coal-based liquids by ionic liquids or deep eutectic solvents. Therefore, the key to separate the actual coal-based liquids by ionic liquids and deep eutectic solvents is their rational molecular design so as to improve the extraction rate and selectivity based on the target compounds, which will inevitably promote the industrialization process of high-valued separation of coal-based liquids.

Key words: ionic liquids, deep eutectic solvents, solvent extraction, hydrogen bonding, intermolecular interaction, separation, coal-based liquids

摘要：

为了实现煤基液体各组分利用价值最大化，本文综述了离子液体和低共熔溶剂对组分组成复杂的煤基液体进行高效萃取分离的研究进展。首先介绍了离子液体和低共熔溶剂的性质及分类；其次根据分离目标的不同，将离子液体和低共熔溶剂对煤基液体典型组分的萃取分离分为四个方面进行阐述：煤基液体提酚、燃料油萃取脱硫、燃料油萃取脱氮、芳烃和脂肪烃的分离。分析表明，离子液体和低共熔溶剂对实际煤基液体的提酚效果较好，能分离出绝大多数的酚类化合物；燃料油萃取脱硫时，离子液体和低共熔溶剂对实际煤基液体的单次脱硫率均不高，需3～5次重复萃取后才能获得理想效果；燃料油中的碱性及非碱性含氮化合物很难被同一种离子液体或低共熔溶剂一次性分离出，导致实际油品的脱氮率较低；大多数离子液体和低共熔溶剂进行芳烃和脂肪烃的分离时不能获得理想的分配系数和选择性，尚无法用于实际芳烃和脂肪烃的分离。氢键、π-π、CH-π、范德华力等分子间相互作用的差异是实现离子液体或低共熔溶剂进行煤基液体典型组分分离的主要原因。依据分离对象，设计合适的离子液体和低共熔溶剂，提高实际煤基液体分离时的萃取率和选择性；分析并解决离子液体和低共熔溶剂用于实际煤基液体各组分分离时可能出现的问题，势必会推进煤基液体高值化分离的工业化进程。

关键词: 离子液体, 低共熔溶剂, 溶剂萃取, 氢键, 分子间相互作用, 分离, 煤基液体