CN110590513B - Method for extracting and separating cresol from phenol-containing oil by using imidazolyl ionic liquid - Google Patents
Method for extracting and separating cresol from phenol-containing oil by using imidazolyl ionic liquid Download PDFInfo
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- CN110590513B CN110590513B CN201910982063.4A CN201910982063A CN110590513B CN 110590513 B CN110590513 B CN 110590513B CN 201910982063 A CN201910982063 A CN 201910982063A CN 110590513 B CN110590513 B CN 110590513B
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- C07C37/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom of a six-membered aromatic ring
- C07C37/68—Purification; separation; Use of additives, e.g. for stabilisation
- C07C37/685—Processes comprising at least two steps in series
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- C07C37/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom of a six-membered aromatic ring
- C07C37/68—Purification; separation; Use of additives, e.g. for stabilisation
- C07C37/70—Purification; separation; Use of additives, e.g. for stabilisation by physical treatment
- C07C37/72—Purification; separation; Use of additives, e.g. for stabilisation by physical treatment by liquid-liquid treatment
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- C07C37/68—Purification; separation; Use of additives, e.g. for stabilisation
- C07C37/70—Purification; separation; Use of additives, e.g. for stabilisation by physical treatment
- C07C37/74—Purification; separation; Use of additives, e.g. for stabilisation by physical treatment by distillation
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- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C39/00—Compounds having at least one hydroxy or O-metal group bound to a carbon atom of a six-membered aromatic ring
- C07C39/02—Compounds having at least one hydroxy or O-metal group bound to a carbon atom of a six-membered aromatic ring monocyclic with no unsaturation outside the aromatic ring
- C07C39/06—Alkylated phenols
- C07C39/07—Alkylated phenols containing only methyl groups, e.g. cresols, xylenols
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Abstract
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 for reuse 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.
Description
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 an 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. 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, the cresol in the coal tar is extracted economically and efficiently, and the comprehensive processing and utilization value of the coal tar is greatly improved. 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 Using an extraction-stripping-rectification method. The use of a stripping agent increases the number of process steps while reducing the purity of the cresol.
In the literature [ Screening monaetholamine As Solvent to Extract Phenols from alk-ane. Energy & fuels.2017, 31, 12997-13009] Monoethanolamine is selected As an extracting agent, and a method of extraction-rectification is used for obtaining pure cresol and realizing the reutilization of the extracting agent.
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 back extractant enables 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 cresol in the phenol-containing oil is selectively extracted through a liquid-liquid extraction tower, then the mixture of the cresol and the ionic liquid enters a decompression rectifying tower, the boiling point of the cresol is about 148 ℃ under the pressure of 20kPa, the separation of the cresol and the ionic liquid is easily realized through a distillation mode, and the separated ionic liquid can be recycled. The invention does not introduce other components, saves the cost and ensures the quality of cresol products; 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 from phenol-containing oil by using ionic liquid, developing a suitable process flow and realizing cyclic utilization 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 and obtain the cresol with high quality, 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 imidazolyl ionic liquid at the tower bottom, and recycling the ionic liquid after the ionic liquid is recovered to normal pressure.
(3) The device that this separation method adopted includes liquid-liquid extraction tower (Ext), decompression pump (P1), decompression rectifying column (Dis), force (P2) that connect in order, wherein liquid-liquid extraction tower (Ext) bottom of the tower export with decompression pump (P1) connect, decompression pump (P1) export with decompression rectifying column (Dis) access connection, decompression rectifying column (Dis) bottom of the tower export with force (P2) access connection, force (P2) export and liquid-liquid extraction tower (Ext) extractant feed inlet connect.
2. In the invention, the operating pressure of the liquid-liquid extraction tower is 1atm, the operating temperature is 25-35 ℃, and the number of theoretical plates is 4-12.
3. In the invention, the operating pressure of the vacuum distillation tower is 20kPa, the number of theoretical plates is 35 to 60, and the reflux ratio is 1 to 3.
4. The mass ratio of the phenolic oil to the extraction solvent is 1-10, the extractant is a designed ionic liquid, the cation is 1-ethyl-3-methylimidazole (EMIM) or 1-butyl-3-methylimidazole (BMIM), and the anion is thiocyanate (-SCN), methyl sulfate (-DMP) or dimethyl phosphate (-CH) 3 SO 4 ) And the anions and the cations are combined randomly to obtain the ionic liquid structure.
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 cresol in the invention is as follows: 92.36 to 99.85 percent, and the recovery rate of the ionic liquid is 98.00 to 99.50 percent.
[ 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 cresol products is improved, and the used extracting agent is a green extracting agent and cannot cause pollution to the environment.
(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 are as follows:
an Ext-liquid extraction column; p1-a pressure reducing pump; dis-vacuum rectification tower; a P2-booster 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.
Example 1
The phenolic oil-containing raw material obtained from coal tar comprises the following components: 60wt% of n-hexane, 10wt% of toluene, 10wt% of p-cresol, 10wt% of o-cresol and 10wt% of m-cresol. The mass ratio of the phenolic oil to the extraction solvent is 10, and the ionic liquid extractant is [ EMIM ] [ SCN ]. The liquid-liquid extraction tower has the operation temperature of 25 ℃, the pressure of 1atm, 4 theoretical plates, the phenolic oil is fed at the bottom of the tower, and the extracting agent is fed at the top of the tower. The theoretical plate number of the reduced pressure distillation tower is 35, the material is fed in the middle section of the distillation tower, the tower pressure is 20kpa, and the reflux ratio is 1.0. 99.16wt% of cresol product is extracted from the top of the tower, and the extraction efficiency is 92.36%. 99.56wt% of ionic liquid is extracted from the bottom of the tower, the recovery rate is 98.50%, and the ionic liquid is recycled to the liquid-liquid extraction tower for reuse.
Example 2
The phenolic oil-containing raw material obtained from coal tar comprises the following components: 60wt% of n-hexane, 10wt% of toluene, 10wt% of p-cresol, 10wt% of o-cresol and 10wt% of m-cresol. The mass ratio of the phenolic oil to the extraction solvent is 5][CH 3 SO 4 ]. The operating temperature of the liquid-liquid extraction tower is 30 ℃, the pressure is 1atm, the number of theoretical plates is 8, the phenolic oil is fed at the bottom of the tower, and the circulating extractant is fed at the top of the tower. The theoretical plate number of the decompression rectifying tower is 50, the middle section of the rectifying tower is fed, and the tower isThe pressure was 20kpa and the reflux ratio was 3.0. 99.34wt% of cresol product is extracted from the tower top, and the extraction efficiency is 98.80%. 99.62wt% of ionic liquid is extracted from the bottom of the tower, the recovery rate is 99.50%, and the ionic liquid is recycled to the liquid-liquid extraction tower for reuse.
Example 3
The phenolic oil-containing raw material obtained from coal tar comprises the following components: 60wt% of n-hexane, 10wt% of toluene, 10wt% of p-cresol, 10wt% of o-cresol and 10wt% of m-cresol. The mass ratio of the phenolic oil to the extraction solvent is 5. The operating temperature of the liquid-liquid extraction tower is 35 ℃, the pressure is 1atm, the number of theoretical plates is 12, the phenolic oil is fed at the bottom of the tower, and the circulating extractant is fed at the top of the tower. The theoretical plate number of the reduced pressure rectifying tower is 60, the material is fed in the middle section of the rectifying tower, the tower pressure is 20kpa, and the reflux ratio is 3.0. 98.15wt% of cresol product is extracted from the top of the tower, and the extraction efficiency is 96.25%. 99.56wt% of ionic liquid is extracted from the bottom of the tower, the recovery rate is 99.32%, and the ionic liquid is recycled to the liquid-liquid extraction tower for reuse.
Example 4
The phenolic oil-containing raw material obtained from coal tar comprises the following components: 60wt% of n-hexane, 10wt% of toluene, 10wt% of p-cresol, 10wt% of o-cresol and 10wt% of m-cresol. The mass ratio of the phenolic oil to the extraction solvent is 8][CH 3 SO 4 ]. The operating temperature of the liquid-liquid extraction tower is 30 ℃, the pressure is 1atm, the number of theoretical plates is 12, the phenolic oil is fed at the bottom of the tower, and the circulating extractant is fed at the top of the tower. The number of theoretical plates of the vacuum distillation tower is 48, the material is fed at the middle section of the distillation tower, the tower pressure is 20kpa, and the reflux ratio is 3.0. 99.15wt% of cresol product is extracted from the top of the tower, and the extraction efficiency is 95.32%. 99.26wt% of ionic liquid is extracted from the bottom of the tower, the recovery rate is 99.63%, and the ionic liquid is recycled to the liquid-liquid extraction tower for reuse.
Example 5
The phenolic oil-containing raw material obtained from coal tar comprises the following components: 60wt% of n-hexane, 10wt% of toluene, 10wt% of p-cresol, 10wt% of o-cresol and 10wt% of m-cresol. The mass ratio of the phenolic oil to the extraction solvent is 2][CH 3 SO 4 ]. The liquid-liquid extraction tower has an operating temperature of 25 deg.C, a pressure of 1atm, a theoretical plate number of 12, and a content ofThe phenol oil is fed at the bottom of the column and the circulating extractant at the top of the column. The theoretical plates of the reduced pressure distillation tower are 35, the material is fed into the middle section of the distillation tower, the tower pressure is 20kpa, and the reflux ratio is 3.0. 99.36wt% of cresol product is extracted from the top of the tower, and the extraction efficiency is 99.25%. 99.43wt% of ionic liquid is extracted from the bottom of the tower, the recovery rate is 99.26%, and the ionic liquid is recycled to the liquid-liquid extraction tower for reuse.
Example 6
The phenolic oil-containing raw material obtained from coal tar comprises the following components: 60wt% of n-hexane, 10wt% of toluene, 10wt% of p-cresol, 10wt% of o-cresol and 10wt% of m-cresol. The mass ratio of the phenolic oil to the extraction solvent is 10. The operating temperature of the liquid-liquid extraction tower is 35 ℃, the pressure is 1atm, the number of theoretical plates is 12, the phenolic oil is fed at the bottom of the tower, and the circulating extractant is fed at the top of the tower. The theoretical plate number of the reduced pressure rectifying tower is 60, the material is fed in the middle section of the rectifying tower, the tower pressure is 20kpa, and the reflux ratio is 3.0. 98.86wt% of cresol product is extracted from the top of the tower, and the extraction efficiency is 92.36%. 99.73wt% of ionic liquid is extracted from the bottom of the tower, the recovery rate is 98.00%, and the ionic liquid is recycled to the liquid-liquid extraction tower for reuse.
Example 7
The phenolic oil-containing raw material obtained from coal tar comprises the following components: 60wt% of n-hexane, 10wt% of toluene, 10wt% of p-cresol, 10wt% of o-cresol and 10wt% of m-cresol. The mass ratio of the phenolic oil to the extraction solvent is 1. The operating temperature of the liquid-liquid extraction tower is 35 ℃, the pressure is 1atm, the number of theoretical plates is 8, the phenolic oil is fed at the bottom of the tower, and the circulating extractant is fed at the top of the tower. The theoretical plates of the vacuum distillation tower are 48, the middle section of the distillation tower is fed, the tower pressure is 20kpa, and the reflux ratio is 2.5. 99.85wt% of cresol products are extracted from the top of the tower, and the extraction efficiency is 92.69%. 99.68wt% of ionic liquid is extracted from the bottom of the tower, the recovery rate is 99.50%, and the ionic liquid is recycled to the liquid-liquid extraction tower for reuse.
Note: the calculation method of the extraction efficiency of the cresol comprises the following steps: (the sum of the mass of the o-cresol, the m-cresol and the p-cresol extracted from the tower top/the sum of the mass of the o-cresol, the m-cresol and the p-cresol in the feeding) x 100 percent.
Claims (3)
1. A method for extracting and separating cresol from phenol-containing oil by using imidazolyl ionic liquid is characterized in that one of imidazolyl ionic liquid 1-ethyl-3-methylimidazole thiocyanate, 1-ethyl-3-methylimidazole methyl sulfate and 1-ethyl-3-methylimidazole dimethyl phosphate is used as an extracting agent to separate phenol-containing oil with the molar composition of 60% of n-hexane, 10% of toluene, 10% of p-cresol, 10% of o-cresol and 10% of m-cresol;
the method comprises the following steps:
(1) Using an imidazole-based ionic liquid as an extractant, wherein the mass ratio of the phenolic oil to the extractant is 1 to 10, the imidazole-based ionic liquid is in countercurrent contact with the phenolic oil in an extraction tower, the operating pressure of the extraction tower is 1atm, the operating temperature is 25 to 35 ℃, the number of theoretical plates is 4 to 12, an ionic liquid phase containing cresol is obtained at the bottom of the extraction tower, and a dephenolized oil phase is formed at the top of the extraction tower;
(2) Carrying out reduced pressure rectification on the cresol-containing ionic liquid phase, wherein the operating pressure of a reduced pressure rectification tower is 20kPa, the number of theoretical plates is 35 to 60, the feeding position is the middle section of the reduced pressure rectification tower, the reflux ratio is 1 to 3, 98.15 to 99.85 weight percent of cresol products are obtained at the tower top, imidazolyl ionic liquid is obtained at the tower bottom, and the ionic liquid is recycled after normal pressure is recovered;
(3) The device that this separation method adopted includes liquid-liquid extraction tower (Ext), decompression pump (P1), decompression rectifying column (Dis), force (P2) that connect in order, wherein liquid-liquid extraction tower (Ext) bottom of the tower export with decompression pump (P1) connect, decompression pump (P1) export with decompression rectifying column (Dis) access connection, decompression rectifying column (Dis) bottom of the tower export with force (P2) access connection, force (P2) export and liquid-liquid extraction tower (Ext) extractant feed inlet connect.
2. The device for extracting and separating cresol from coal tar by using the imidazolyl ionic liquid as in claim 1, which further comprises a mixer for the ionic liquid circulating flow and a fresh ionic liquid extracting agent.
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 recovery rate of the cresol is 92.36-99.25%, and the recovery rate of the ionic liquid is 98.00-99.50%.
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| 焦油中酚类化合物的分离研究;庄绪磊;《中国优秀硕博士学位论文全文数据库（硕士）工程科技I辑》;20151231(第4期);第30-35页 * |
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