阅读说明：本技术 一种咪唑基离子液体分离煤焦油中苯酚的方法 (Method for separating phenol from coal tar by using imidazolyl ionic liquid ) 是由 高军 徐鑫 李傲 马艺心 徐冬梅 张连正 赵萍萍 于 2019-10-16 设计创作，主要内容包括：本发明涉及一种利用咪唑基离子液体萃取分离煤焦油中苯酚的方法。该方法特征是：采用设计的不同阴阳离子的咪唑基离子液体作为萃取剂,如1-乙基-3-甲基咪唑乳酸盐、1-丁基-3-甲基咪唑高氯酸盐等。在室温下将萃取剂与定量、定浓度的苯酚模型油进行搅拌,静置后得到分层的两相,实现含苯酚与煤焦油混合物的有效分离；通过分液的方式分离出下层离子液体相,用乙酸乙酯进行反萃取,搅拌后静置分层,将上层油相精馏,在剂油比1：1的情况下,用1-乙基-3-甲基咪唑乳酸盐萃取苯酚,苯酚的回收率高达97.6%；向反萃取后的下层离子液体相中继续加入相同配比的苯酚模型油进行萃取,循环萃取5-15次后萃取剂仍表现出很强的萃取分离能力。本发明所使用的咪唑基离子液体萃取剂分离效率高、循环萃取能力强、环境友好且可以重复使用,回收率可达85.6%以上。(The invention relates to a method for extracting and separating phenol in coal tar by using imidazolyl ionic liquid. The method is characterized in that: imidazolyl ionic liquid with different anions and cations is adopted as an extracting agent, such as 1-ethyl-3-methylimidazole lactate, 1-butyl-3-methylimidazole perchlorate and the like. Stirring the extractant and phenol model oil with fixed quantity and fixed concentration at room temperature, standing to obtain two layered phases, and realizing effective separation of a mixture containing phenol and coal tar; separating the lower ionic liquid phase by a liquid separation mode, carrying out back extraction by using ethyl acetate, standing and layering after stirring, rectifying the upper oil phase, and adding a solvent into the mixture in a solvent-oil ratio of 1: under the condition of 1, the 1-ethyl-3-methylimidazole lactate is used for extracting phenol, and the recovery rate of the phenol is as high as 97.6 percent; and continuously adding phenol model oil with the same proportion into the back-extracted lower-layer ionic liquid phase for extraction, wherein the extractant still shows strong extraction separation capacity after 5-15 times of circulating extraction. The imidazolyl ionic liquid extractant used in the invention has high separation efficiency, strong cyclic extraction capability, environmental friendliness and reusability, and the recovery rate can reach more than 85.6%.)

1. A method for separating phenol from coal tar by taking ionic liquid as an extracting agent is characterized by comprising the following steps: adding imidazolyl ionic liquid (the mass ratio of the ionic liquid to the model oil is 0.1-1) into phenol model oil, stirring at room temperature, standing for phase separation, and finally obtaining an upper oil phase with phenol removed and a lower ionic liquid phase with phenol; adding a back extraction reagent into the ionic liquid phase at the lower layer, stirring, standing and phase splitting, wherein the upper layer is a back extraction reagent phase containing phenol, the ionic liquid extractant is obtained at the lower layer, and the imidazolyl ionic liquid can be regenerated for use; adding model oil with the same mass ratio into the regenerated ionic liquid, and performing circulating extraction; and rectifying the obtained phenol-containing back extraction reagent phase to obtain phenol and a back extraction reagent, wherein the back extraction reagent is reused.

2. The method according to claim 1, wherein the imidazolyl ionic liquid is an ionic liquid obtained by any combination of 1-ethyl-3-methylimidazole, 1-butyl-3-methylimidazole cation and anions such as perchlorate, tetrafluoroborate and lactate anion.

3. The process according to claim 1, wherein the extraction temperature is 25-55 ℃.

4. The process according to claim 1, wherein the extraction time is 5-60 min.

5. The method of claim 1, wherein the number of extraction cycles of the ionic liquid extractant is 5 to 15.

6. The method according to claim 1, wherein the model oil is composed of phenol, n-hexane and toluene in a mass ratio of 2: 7: 1, the phenol content of the oil was 20 wt%.

7. The process of claim 1, wherein the recovery of phenol is from 85.6% to 97.6%.

Technical Field

The invention belongs to the field of separation in the coal chemical industry, and relates to synthesis of an ionic liquid extracting agent with high separation efficiency, environmental friendliness and recyclability and application of the ionic liquid extracting agent in separation of phenol components in coal tar.

Background

Coal tar, a by-product of coal coking, also known as coal pyrolysis oil, is a major feedstock in the coal chemical industry, as it contains many useful and valuable components, such as: aromatic hydrocarbons such as benzene, toluene, naphthalene, anthracene and the like, and aromatic oxygen-containing compounds are important sources of chemicals and fuel oil, and have been widely applied to fine chemical industries such as phenolic resin, synthetic fiber, pesticide and medicine. Wherein, the content of phenols in the low-temperature coal tar is up to 20-30%, the phenol content is the highest, and the price of the phenol compounds is three to four times higher than that of the coal tar, and the extraction of the phenol from the coal tar can obviously improve the economic benefit of coal chemical enterprises. Therefore, the method is very meaningful for separating high-value-added compounds such as phenol in the coal tar.

There are many reports in the literature on methods for separating phenols from coal tar and fractions thereof, and chemical conversion is common. Gao et al [ Efficient separation of phenols from oil by acid-based purification. Chemical Engineering Journal, 2015, 281 (749-. However, large amounts of waste water containing phenolic compounds are produced, which severely corrodes equipment and, due to their high toxicity and mutagenic effect on humans, animals and aquatic life, phenolic compounds are prioritized pollutants by the european union and the us epa, and their concentration in the waste water is subject to many restrictions or strict regulations.

Compared with the former method, the solvent extraction separation, especially the liquid-liquid extraction, has the advantages of large productivity, high recoverability, low product cost and the like, and the method is widely applied to the coking industry. Gai et al [ A solvent based separation method for phenolic compounds from low-temperature co-reactor, journal of Cleaner Production, 2019, 223:1-11.]Using ethanolamine as solvent, toThe coal tar distillate containing phenol is separated and researched, the extraction efficiency of the phenol can reach 95.36%, the extractant can eliminate secondary pollutants generated in the alkali washing process, and the method has relatively high industrial application prospect, but the extraction rate of the method is lower than that of the traditional alkali washing process. Therefore, ionic liquids have been widely studied and used for separation or removal of components in view of their high selectivity and designability. Furthermore, it has been reported on the Separation of phenol from coal tar that Hou et al [ Separation of phenols from Oil Using Imidazolium-Based Ionic liquids, 2013, 52: 18071-18075.]Using [ BMIM]Cl and the like are used for extracting and separating phenol in the low-temperature coal tar distillate, the extraction rate of the ionic liquid to the phenol in the model oil is more than 90%, the ionic liquid can be recycled, but the ionic liquid contains Cl^-It may cause serious corrosion to steel equipment. Zhuang et al [ Study on the extraction of phenolic compounds from model oil by using ionic liquid 2014, 54, 310-.]Using [ EMIM][NTf₂]The separation of phenol in coal tar model oil is researched, the ionic liquid shows high selectivity to phenol and low viscosity, but the extraction rate of the ionic liquid is relatively low. Therefore, in consideration of the advantages of the ionic liquid, a thermodynamically stable, green, economic and recyclable ionic liquid extractant is found to realize efficient and highly selective separation of phenol in the coal tar, which is of great significance for deep utilization of the coal tar.

Disclosure of Invention

[ problem to be solved ]

The invention aims to design an imidazole type ionic liquid extracting agent in a targeted manner aiming at the problems in the separation of phenol in the coal tar at present, and provides a method for efficiently separating phenol. The method takes imidazolyl ionic liquid as an extracting agent, and realizes the separation of phenol in coal tar and fractions thereof by a mode that strong polar atoms contained in anions and cations form hydrogen bond interaction with phenol.

[ solution ]

The purpose of the invention is realized by the following technical scheme.

The invention provides a method for extracting and separating phenol in coal tar by using an imidazolyl ionic liquid extractant, which comprises the following steps: adding imidazolyl ionic liquid (the mass ratio of the ionic liquid to the model oil is 0.1-1) into phenol model oil, stirring at room temperature, standing for phase separation, and finally obtaining an upper oil phase with phenol removed and a lower ionic liquid phase with phenol; adding a back extraction reagent into the ionic liquid phase at the lower layer, stirring, standing and phase splitting, wherein the upper layer is a back extraction reagent phase containing phenol, the ionic liquid extractant is obtained at the lower layer, and the imidazolyl ionic liquid can be regenerated for use; adding model oil with the same mass ratio into the regenerated ionic liquid, and performing circulating extraction; distilling the obtained phenol-containing back extraction reagent phase to obtain phenol and a back extraction reagent, wherein the back extraction reagent is reused; separating phenol from the stripping agent by rectification to obtain a pure phenol product.

In the above method, the imidazole-based ionic liquid extractant used comprises: the ionic liquid structure is obtained by randomly combining 1-ethyl-3-methylimidazole, 1-butyl-3-methylimidazole cations, perchlorate, tetrafluoroborate, lactate anions and other anions and cations.

In the method, the extraction temperature of the imidazolyl ionic liquid is 25-55 ℃.

In the method, the extraction time of the imidazolyl ionic liquid is 5-60 min.

In the method, the ionic liquid extractant is subjected to cyclic extraction for 5-15 times in the separation process of phenol in the coal tar.

In the method, the solvent oil in the adopted phenol model oil is composed of toluene, n-hexane and phenol.

In the method, the extraction recovery rate of the phenol is 85.6-97.6%.

The principle of the method is as follows: phenol and strong polar atoms on the ionic liquid extractant can generate intermolecular hydrogen bonding action, so that the high-efficiency and high-selectivity separation of phenol in coal tar and fractions thereof is realized. The imidazolyl ionic liquid extractant has carbonyl, hydroxyl and other structures, so that the imidazolyl ionic liquid extractant has higher stability, extraction capacity and selectivity than common ionic liquid extractants.

[ advantageous effects ]

Compared with the prior art, the invention mainly has the following beneficial effects:

the imidazolyl ionic liquid extractant used in the invention has high extraction efficiency, stable property and strong cyclic extraction capability; the extracted ionic liquid can be regenerated, the extraction agent can be reused, and the separation efficiency is hardly reduced.

[ detailed description of the invention ]

The present invention will be further described with reference to specific examples, which are intended to provide an imidazole-based ionic liquid extractant for separating phenol from coal tar, but the present invention is not limited to the following examples, and various modifications are included within the technical scope of the present invention without departing from the spirit of the invention as described above and below.

The specific configuration of the mixed model oil is as follows: coal tar or its different fractions are complex in composition and mainly consist of neutral hydrocarbons (aromatic hydrocarbons, aliphatic hydrocarbons) and acidic phenolic substances. In the preparation of the phenol model oil, normal hexane (represented by aliphatic hydrocarbon substances), phenol (represented by phenolic substances) and toluene (represented by aromatic hydrocarbon substances) are added, and the model oil with the corresponding mass ratio is prepared by referring to the compositions of the partial substances in the real fraction. 700.99g of n-hexane and 200.04g of phenol were accurately weighed and dissolved in 100.99g of toluene to prepare a model oil containing 20.0% by mass of phenol.

Ionic liquid extractant extraction separation experiment: measuring a certain amount of model oil in a sample bottle with magnetons, adding a certain amount of ionic liquid extractant, stirring at room temperature for 5-60min, standing for 30min, absorbing a proper amount of upper oil phase, performing quantitative analysis by a gas chromatograph, measuring the content of phenol before and after extraction, and calculating the extraction rate of the ionic liquid on the phenol; carrying out back extraction on the obtained lower-layer ionic liquid phase by using ethyl acetate, stirring, standing and carrying out phase separation, carrying out cyclic extraction on the ionic liquid obtained by lower-layer separation, and continuously adding phenol model oil with the same mass ratio into the separated ionic liquid for extraction; and (4) rectifying the upper layer after the back extraction to obtain phenol, and calculating the recovery rate of the phenol.

Analyzing the composition of raffinate phase by gas chromatography, using a Lunan SP-7820 gas chromatograph, a PEG-20M (50M × 0.25 mm × 0.5 μ M) capillary column as a chromatographic column, and a hydrogen flame ionization detector; p-xylene as an internal standard substance, nitrogen as a carrier gas, a vaporizing chamber temperature of 250 ℃, a detector temperature of 270 ℃, a temperature programming: the temperature is kept for 1min at 80 ℃, and then the temperature is increased to 220 ℃ at the speed of 40 ℃/min, and the temperature is kept for 5.5 min.