阅读说明：本技术 一种利用咪唑基离子液体萃取分离含酚油中甲酚的方法 (Method for extracting and separating cresol from phenol-containing oil by using imidazolyl ionic liquid ) 是由 高军 李傲 徐鑫 马艺心 张连正 徐冬梅 赵萍萍 于 2019-10-16 设计创作，主要内容包括：本发明提供了一种使用咪唑基离子液体萃取分离含酚油中甲酚的方法。咪唑基离子液体如1-乙基-3-甲基咪唑硫氰酸盐、1-乙基-3-甲基咪唑硫酸甲酯盐和1-丁基-3-甲基咪唑磷酸二甲酯盐均具有分离效果。本发明提出的技术方案为：将含酚油由萃取塔的塔底引入,离子液体萃取剂由萃取塔的塔顶引入,二者进行多级逆流萃取。萃取后油相从塔顶采出,含甲酚的离子液体经过减压后进入精馏塔,减压操作可降低甲酚的沸点,从而减少耗能。甲酚由精馏塔的塔顶采出,离子液体从精馏塔塔底采出,回到常压后可循环至萃取塔再利用。该方法工艺简单,易实现连续操作,处理后可得高纯度的甲酚。用离子液体作萃取剂可以提高萃取效果,减少有机萃取剂对环境的污染。(The invention provides a method for extracting and separating cresol from phenol-containing oil by using imidazolyl ionic liquid. Imidazole-based ionic liquids such as 1-ethyl-3-methylimidazole thiocyanate, 1-ethyl-3-methylimidazole methyl sulfate and 1-butyl-3-methylimidazole dimethyl phosphate have a separating effect. The technical scheme provided by the invention is as follows: introducing the phenolic oil from the bottom of the extraction tower, introducing the ionic liquid extractant from the top of the extraction tower, and performing multi-stage countercurrent extraction on the phenolic oil and the ionic liquid extractant. The extracted oil phase is extracted from the top of the tower, the cresol-containing ionic liquid is decompressed and then enters a rectifying tower, and the decompression operation can reduce the boiling point of cresol, thereby reducing energy consumption. Cresol is extracted from the top of the rectifying tower, ionic liquid is extracted from the bottom of the rectifying tower, and the ionic liquid can be recycled to the extraction tower after returning to normal pressure. The method has simple process, is easy to realize continuous operation, and can obtain the cresol with high purity after treatment. The ionic liquid is used as an extracting agent, so that the extraction effect can be improved, and the pollution of an organic extracting agent to the environment can be reduced.)

1. A method for extracting and separating cresol from phenol-containing oil by using imidazole-based ionic liquid is characterized by comprising the following steps:

(1) using imidazolyl ionic liquid as an extracting agent, and carrying out countercurrent contact on the imidazolyl ionic liquid and phenol-containing oil in an extraction tower, so as to obtain an ionic liquid phase containing cresol at the bottom of the tower, and obtain a dephenolized oil phase at the top of the tower;

(2) carrying out reduced pressure rectification on the cresol-containing ionic liquid phase to obtain cresol at the tower top and imidazole-based ionic liquid at the tower bottom, wherein the ionic liquid is recycled after the atmospheric pressure is restored;

(3) the device adopted by the separation method comprises a liquid-liquid extraction tower (Ext), a decompression pump (P1), a decompression rectifying tower (Dis) and a pressure pump (P2), wherein the outlet at the bottom of the liquid-liquid extraction tower (Ext) is connected with the decompression pump (P1), the outlet of the decompression pump (P1) is connected with the inlet of the decompression rectifying tower (Dis), the outlet at the bottom of the decompression rectifying tower (Dis) is connected with the inlet of the pressure pump (P2), and the outlet of the pressure pump (P2) is connected with the feed inlet of an extractant of the liquid-liquid extraction tower (Ext).

2. The method for extracting and separating the cresol from the phenol-containing oil by using the imidazolyl ionic liquid as claimed in claim 1, wherein the operating pressure of the extraction tower is 1atm, the operating temperature is 25 ~ 35 ℃, and the number of theoretical plates is 4 ~ 12.

3. The method for extracting and separating the cresol from the phenol-containing oil by using the imidazolyl ionic liquid as claimed in claim 1, wherein the operating pressure of the vacuum rectification tower is 20kPa, the number of theoretical plates is 35 ~ 60 blocks, the feeding position is the middle section of the vacuum rectification tower, and the reflux ratio is 1 ~ 3.

4. The method for extracting and separating cresol from phenol-containing oil by using imidazole-based ionic liquid as claimed in claim 1, wherein the mass ratio of the phenol-containing oil to the extracting agent is 1 ~ 10:1, and the extracting agent is an ionic liquid structure obtained by arbitrarily combining 1-ethyl-3-methylimidazole, 1-butyl-3-methylimidazole cation and thiocyanate, methyl sulfate and dimethyl phosphate anion.

5. The method for extracting and separating the cresol from the phenol-containing oil by using the imidazolyl ionic liquid as claimed in claim 1, wherein the adopted device further comprises a mixer of the ionic liquid circulating flow and the fresh ionic liquid extracting agent.

6. The method for extracting and separating the cresol from the phenol-containing oil by using the imidazolyl ionic liquid as claimed in claim 1, wherein the recovery rate of the cresol is 92.36% ~ 99.85.85%, and the recovery rate of the ionic liquid is 98.00% ~ 99.50.50%.

Technical Field

The invention belongs to the field of chemical separation, and relates to a method for extracting and separating cresol from phenol-containing oil by using an ionic liquid, in particular to a method for extracting and separating cresol from phenol-containing oil by using an ionic liquid extractant, obtaining pure cresol by vacuum rectification, and recovering the ionic liquid.

Background

Coal tar generated in the coal pyrolysis process is taken as an important high-added-value product source and widely applied to industries such as chemical industry, medicine, dye, pesticide, plastic, synthetic fiber, synthetic rubber, refractory high-temperature materials, national defense industry, carbon and the like, wherein a part of polycyclic aromatic hydrocarbon compounds cannot be replaced by petroleum industry. The content of phenolic substances in the coal tar is very high and reaches 25 to 30 percent. Wherein, the cresol is an important chemical raw material, has high added value, and is a valuable raw material and an important fine chemical intermediate for producing a plurality of fine chemical industries such as disinfectants, preservatives, rubber anti-aging agents, pesticides, medicines, explosives and the like. Therefore, cresol in the coal tar is extracted economically and efficiently, and the comprehensive processing and utilization value of the coal tar is improved to a great extent. Because the components of the coal tar are too complex, researchers adopt an equivalent simplified method to prepare the phenolic oil to replace the coal tar for experimental research. The invention relates to a method for separating cresol from equivalent phenol-containing oil of coal tar by adopting imidazolyl ionic liquid.

The literature [ Separation of Phenols from Oil Using Imidazolium-Based Ionic liquids. Ind. Eng. chem. Res. 2013, 52, 18071-18075 ] uses nicotinamide as extractant, and about 85% of the extractant can be recycled by means of extraction-stripping-rectification. The use of a stripping agent increases the number of process steps while reducing the purity of the cresol.

In the literature [ Screening Monoethanolamines As Solvent to Extract Phenols from alk-ane. energy & fuels.2017, 31, 12997-.

The patent [ a method and a device for separating various phenols from crude phenol of medium-low temperature coal tar ] uses phosphoric acid and sulfuric acid as extracting agents, and is not beneficial to environmental protection.

The disadvantages and shortcomings of the above separation techniques are: the cost of the separation process is high; the used organic extractant pollutes the environment to a certain extent and does not meet the current aim of green chemistry; the use of the stripping agent leads other substances to be introduced into the system and influences the product purity to a certain extent; the process flow is relatively complex.

The invention adopts a method of firstly extracting under normal pressure and then rectifying under reduced pressure to recover the extractant. Specifically, the invention utilizes the pressure to reduce the boiling point of cresol, and the ionic liquid has the advantages of extremely low vapor pressure and non-volatility and is easy to separate from cresol. The method comprises the following steps of firstly, selectively extracting cresol from phenol-containing oil through a liquid-liquid extraction tower, then, feeding a mixture of the cresol and ionic liquid into a decompression rectifying tower, separating the cresol from the ionic liquid easily through a distillation mode under the pressure of 20kPa and the boiling point of the cresol of about 148 ℃, wherein the separated ionic liquid can be recycled. The invention does not introduce other components, saves the cost and ensures the quality of the cresol product; the process is simple and the device is reasonable; can simultaneously prepare high-purity cresol and realize the recycling of the ionic liquid extractant.

Disclosure of Invention

[ problem to be solved ]

The invention aims to provide a separation method for extracting and separating cresol in phenol-containing oil by using ionic liquid, developing a suitable process flow and realizing the recycling of the ionic liquid.

[ solution ]

The invention provides a method for extracting and separating cresol and phenol-containing oil by using imidazolyl ionic liquid. Meanwhile, the invention overcomes the defects in the prior art and provides a method for separating cresol from coal tar by liquid-liquid extraction and then decompression rectification. The invention utilizes the change of the boiling point of the cresol along with the pressure, adopts a vacuum rectification mode to separate the cresol to obtain high-quality cresol, and simultaneously realizes the recycling of the ionic liquid. The method solves the problems of conventional cresol sequence separation, does not use organic back extractant, reduces the separation cost and improves the product purity.

The invention is realized by the following technical scheme.

1. The method takes the imidazolyl ionic liquid as an extracting agent to realize the separation of cresol in phenol-containing oil, and comprises the following steps.

(1) Imidazole-based ionic liquid is used as an extracting agent and is in countercurrent contact with phenol-containing oil in an extraction tower, a cresol-containing ionic liquid phase is obtained at the bottom of the extraction tower, and a dephenolized oil phase is arranged at the top of the extraction tower.

(2) And (3) carrying out reduced pressure rectification on the cresol-containing ionic liquid, obtaining a cresol product at the tower top, obtaining the imidazolyl ionic liquid at the tower bottom, and recycling the ionic liquid after the ionic liquid is recovered to normal pressure.

(3) The device adopted by the separation method comprises a liquid-liquid extraction tower (Ext), a decompression pump (P1), a decompression rectifying tower (Dis) and a pressure pump (P2), wherein the outlet at the bottom of the liquid-liquid extraction tower (Ext) is connected with the decompression pump (P1), the outlet of the decompression pump (P1) is connected with the inlet of the decompression rectifying tower (Dis), the outlet at the bottom of the decompression rectifying tower (Dis) is connected with the inlet of the pressure pump (P2), and the outlet of the pressure pump (P2) is connected with the feed inlet of an extractant of the liquid-liquid extraction tower (Ext).

2. In the present invention, the operating pressure of the lle column was 1atm, the operating temperature was 25 ~ 35 ℃, and the number of theoretical plates was 4 ~ 12.

3. In the present invention, the operating pressure of the vacuum distillation column was 20kPa, the number of theoretical plates was 35 ~ 60 pieces, and the reflux ratio was 1 ~ 3.

4. The mass ratio of the phenolic oil to the extraction solvent is 1 ~ 10:1, the extraction agent is designed ionic liquid, cations are 1-ethyl-3-methylimidazole (EMIM) and 1-butyl-3-methylimidazole (BMIM), and anions are thiocyanate (-SCN), methyl sulfate (-DMP) and dimethyl phosphate (-CH)₃SO₄) And the ionic liquid structure is obtained by randomly combining the anions and the cations.

5. The apparatus employed in the present invention also includes a mixer of the ionic liquid recycle stream and fresh ionic liquid extractant.

6. The extraction efficiency of the cresol in the invention is 92.36 ~ 99.85.85%, and the recovery rate of the ionic liquid is 98.00% ~ 99.50.50%.

[ advantageous effects ]

Compared with the prior art, the invention has the following beneficial effects.

(1) The cost of the separation process is reduced.

(2) The product does not use a stripping agent, and the product purity is improved.

(3) The ionic liquid extraction and recovery process is realized, the process is simple, and the device is reasonable.

(4) The yield of the cresol product is improved, and the used extractant is a green extractant, so that the environment is not polluted.

(5) The liquid-liquid extraction and the vacuum rectification systems are both continuous rectification operation, which is beneficial to realizing large-scale industrial production.

[ description of the drawings ]

FIG. 1 is a flow chart of the liquid-liquid extraction-vacuum rectification process for separating cresol from phenol-containing oil.

Reference numerals:

ext-liquid extraction column; p1-reduced pressure pump; dis-vacuum rectification tower; p2-pressure pump; the other numbers represent the respective streams.

[ detailed description of the invention ]

The technical solutions of the present invention will be described clearly and completely below, and it should be apparent that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.