A method for separating an oil phenol mixture by coupling of eutectic solvent extraction and rectification

Abstract

The application provides a method for separating oil phenol mixture by eutectic solvent extraction coupled with rectification, which comprises the following steps: firstly, stirring and mixing a hydrogen bond acceptor and a hydrogen bond donor according to a molar ratio to obtain a eutectic solvent extractant; secondly, adding the extractant into an extraction tower to extract the oil phenol mixture in a countercurrent manner to obtain a dephenolized oil and an extract liquid; thirdly, flashing the extract liquid in a flash tank F1 to remove a small amount of neutral oil dissolved in the extract liquid; fourthly, feeding the extract liquid from which the neutral oil is removed into a flash tank F2 to obtain a phenol-rich fraction and a partially regenerated extractant by flashing; fifthly, feeding the phenol-rich fraction into a azeotropic rectification tower to separate the phenol-rich fraction, and obtaining a low-boiling azeotrope at the top of the tower, which is recycled to the bottom of the extraction tower together with a neutral oil fraction to be re-extracted; and finally, separating a phenol product and a hydrogen bond donor mixture at the bottom of the rectification tower by rectification to obtain the phenol product and the hydrogen bond donor. The method has high separation efficiency, high purity of the phenol product and low neutral oil content (less than 1%); and the extractant used is stable in property, cheap and easy to obtain and recycle.

Description

Technical Field

[0001] This invention relates to a method for separating an oil-phenol mixture by eutectic solvent extraction coupled with distillation. Background Technology

[0002] Coal pyrolysis oil, direct coal liquefaction oil, and biomass pyrolysis oil contain a large amount of phenolic compounds. If these are directly hydrogenated to produce gasoline, diesel, and bio-oil, it not only wastes valuable phenolic compounds and increases hydrogen consumption, but also reduces product value, increases costs, and affects production efficiency.

[0003] Currently, the commonly used industrial methods for separating phenolic compounds from oil-phenol mixtures are alkaline washing and solvent extraction. Alkaline washing uses large amounts of acid and alkali solutions, causing severe corrosion to equipment and generating large quantities of phenol-containing wastewater, significantly increasing production and environmental remediation costs. Solvent extraction commonly uses superheated water, salt solutions, alcohol solutions, sulfolane, and other solvents, but its problems include low selectivity for phenols and the generation of difficult-to-treat phenol-containing wastewater.

[0004] Secondly, conventional ionic liquids or eutectic solvents have high solubility in oil and some contain halide ions, which easily contaminate the oil phase. Due to the π-π conjugation between phenolic compounds and other aromatic compounds in the oil, higher extraction efficiency often results in a greater amount of entrained neutral oil. The main methods for removing entrained neutral oil are back-extraction and nitrogen stripping. Back-extraction requires flash evaporation to recover the back-extractant, and introducing new solvents increases costs. Nitrogen stripping results in the waste of a certain amount of phenolic mixture. Current extractants and processes struggle to simultaneously meet the industrial requirements of an extraction rate of over 99% and a neutral oil content of less than 1%.

[0005] Therefore, developing a novel and efficient technology for separating phenolic compounds from oil-phenol mixtures is of great significance. The extractant used in this method is non-toxic, easily synthesized, and inexpensive, enabling rapid and efficient extraction of high-purity phenol products. Furthermore, the extractant exhibits good stability and weak interaction with neutral oil, allowing for complete removal of the neutral oil through two-stage flash evaporation and distillation. This extraction-coupled distillation process has low energy consumption and significant potential for industrial application. Summary of the Invention

[0006] The purpose of this invention is to solve the problems existing in the separation of phenolic compounds from oil-phenol mixtures, and to propose a highly efficient method for separating phenolic compounds from oil-phenol mixtures. The method of this invention uses a eutectic solvent as the extractant, and achieves the separation of phenolic compounds from oil-phenol mixtures through extraction coupled with distillation, while reducing process energy consumption, as shown in the accompanying drawings. Figure 1 As shown, the extractant used in the method of the present invention is inexpensive, environmentally friendly, and stable, and can be regenerated by flash evaporation or distillation.

[0007] The objective of this invention is achieved through the following technical solution.

[0008] A method for separating an oil-phenol mixture by eutectic solvent extraction coupled with distillation, the method comprising the following steps:

[0009] (1) The hydrogen bond acceptor and hydrogen bond donor are mixed and stirred at a given molar ratio to obtain a eutectic solvent; (2) The eutectic solvent extractant prepared in step (1) is added to the top of the extraction tower T1, so that it and the oil-phenol mixture F1 entering from the bottom of the tower are in countercurrent contact in the tower, and extracted at a given temperature to obtain extract B1 and raffinate D1 (D1 is dephenolized oil); (3) The extract B1 obtained in step (2) is fed into flash tank F1 for flash evaporation to obtain neutral oil-rich fraction D2 and deneutralized oil extract B2, and the neutral oil-rich fraction D2 is returned to the feed liquid oil-phenol mixture F1 for further extraction; (4) The deneutralized oil extract B2 obtained in step (3) is fed into flash tank F2 for flash evaporation to obtain phenol-rich fraction D3 and regenerated extractant B3; (5) The phenol-rich fraction D3 from step (4) enters the azeotropic distillation column T2 for distillation separation. A small amount of neutral oil and phenol azeotrope D4 is obtained at the top of the distillation column. The azeotrope D4 is returned to the bottom of the extraction column T1 for further extraction. A mixture B4 of phenol and a small amount of hydrogen bond donor is obtained at the bottom of the azeotropic distillation column T2. ​​(6) The mixture B4 of phenol and a small amount of hydrogen bond donor obtained in step (5) enters the recovery distillation column T3 for distillation separation. Phenol product D5 is obtained at the top of the column, and a small amount of hydrogen bond donor B5 is obtained at the bottom of the column. The small amount of hydrogen bond donor B5 is mixed with the regenerated extractant B3 from step (4) and returned to the extraction column for reuse. The hydrogen bond acceptor mentioned in step (1) is selected from one or both of betaine and L-carnitine. The hydrogen bond donor mentioned in step (1) is selected from one or both of triethylene glycol and tetraethylene glycol.

[0010] The method described above is characterized in that the molar ratio of hydrogen bond acceptor to hydrogen bond donor in step (1) is 1:3.3 to 1:4.

[0011] In the above method, the characteristic is that the molar ratio of the extractant to the phenol in the raw material in the extraction tower in step (2) is 0.6 to 1.4.

[0012] In the above method, the temperature at which the eutectic solvent extractant separates the oleophenol mixture in step (2) is 25°C to 45°C.

[0013] The method described above is characterized in that the pressure in the flash tank F1 in step (3) is 0.05 atm to 0.1 atm and the temperature is 150°C to 180°C.

[0014] In the above method, the characteristic is that the pressure of the flash tank F2 in step (4) is 0.05 atm to 0.1 atm, and the temperature is 200℃ to 225℃.

[0015] The method described above is characterized in that, in step (5), the number of trays in the distillation column T2 is 30 to 40, the number of feed trays is 20 to 30, and the mass reflux ratio is 1 to 4.

[0016] In the above method, the characteristic is that in step (6), the number of trays in the distillation recovery tower T3 is 30 to 40, the number of feed trays is 20 to 30, and the mass reflux ratio is 1 to 4.

[0017] The principle of this method is as follows: First, both the hydrogen bond acceptor (betaine or L-carnitine) and the hydrogen bond donor (triethylene glycol or tetraethylene glycol) are substances with high boiling points and stable properties. After forming a eutectic solvent through hydrogen bonds, their thermal stability is further improved. Both the hydrogen bond acceptor and the hydrogen bond donor can generate strong hydrogen bonds with phenolic compounds and weak van der Waals forces with neutral oil molecules. Therefore, this eutectic solvent extractant has high extraction capacity and selectivity. Second, the weak van der Waals forces between the extractant and neutral oil allow most of the neutral oil in the eutectic solvent after extraction to be removed by flash evaporation at a relatively low temperature. The content of phenolic compounds in the phenol-rich fraction obtained by high-temperature flash evaporation after removing the neutral oil is much higher than their content in the lowest-component azeotrope formed by phenolic compounds and neutral oil. Therefore, by distillation, neutral oil and phenolic compounds can be extracted from the top of the column as a minimum azeotrope, while the residue at the bottom of the column consists of most of the phenolic compounds and a small amount of entrained extractant. The mixture at the bottom of the column is then subjected to simple distillation to obtain phenolic products, and the small amount of entrained extractant is recycled.

[0018] Compared with traditional methods, the advantages of this method are: (1) high partition coefficient and selectivity of low eutectic solvent; (2) fast extraction speed, high extraction efficiency and simple operation; (3) the extractant used is inexpensive, environmentally friendly, stable and reusable; (4) the method does not use acid and alkali solvents, saves resources, generates no wastewater, has low cost and is environmentally friendly; (5) no new solvent (such as organic solvent diethyl ether) is introduced outside the extractant for back-extraction to reduce the neutral oil content; (6) the extraction coupled distillation process has lower energy consumption than the direct extraction distillation process; (7) the phenol mixture obtained by this method has high purity and low neutral oil content. Attached Figure Description

[0019] To more clearly illustrate the background technology and the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Figure 1 This is a flow chart of the process for separating oil-phenol mixtures using eutectic solvent extraction coupled with distillation, as described in this invention. The flow chart mainly includes:

[0020] The flow chart includes an extraction column (T1), an azeotropic distillation column (T2), a recovery distillation column (T3), flash tanks (F1, F2), a condenser, and a mixer. The main material streams are: oil-phenol mixture feed (F1), supplemental extractant feed (M1), dephenolized oil (D1), extract (B1), extractant B2 after neutralization, neutral oil-rich fraction (D2), phenol-rich fraction (D3), azeotrope of phenol and neutral oil (D4), regenerated extractant (B3), phenol and a small amount of hydrogen bond donor mixture (B4), phenol product (D5), and a small amount of hydrogen bond donor (B5). Detailed Implementation

[0021] The method for separating an oil-phenol mixture by eutectic solvent extraction coupled with distillation according to the present invention will be described in further detail below with reference to embodiments, but this does not limit the present invention. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0022] In this embodiment of the invention, gas chromatography was used to analyze the composition of the liquid product. The gas chromatograph used was a Shimadzu GC-2014 gas chromatograph, with a weakly polar capillary column (HP-5) and a flame ionization detector (FID). The determination method was external standard normalization. The gas chromatographic conditions were: carrier gas N2, vaporization chamber temperature 250℃, FID detector temperature 280℃, and the instrument's temperature program was: 80℃ for 3 min, then increased to 220℃ at a rate of 40℃ / min, and held for 3 min.

[0023] Example 1

[0024] In this embodiment, an extractive distillation separation experiment was conducted using a simulated oleophenol mixture that can form an azeotrope. The oleophenol mixture used was a mixture containing 40% m-cresol, 40% tetrahydronaphthalene, and 20% undecane, wherein tetrahydronaphthalene and undecane were neutral oil components. Hydrogen bond acceptor betaine and hydrogen bond donor triethylene glycol were mixed at a molar ratio of 1:4 and magnetically stirred at 90°C for 6 hours to ensure complete reaction, yielding a eutectic solvent extractant. A eutectic solvent extractant with a flow rate of 100 kmol / h was introduced from the top of extraction column T1, while the oleophenol mixture feedstock with a flow rate of 250 kmol / h was introduced from the bottom of the extraction column (the molar ratio of extractant to intermediate cresol in the feedstock was 1:1). Countercurrent contact extraction was carried out in extraction column T1 at a temperature of 25°C and a pressure of 1 atm. The top of the column yielded raffinate D1 (removed phenol oil) at a flow rate of 101.53 kmol / h, with a neutral oil content of 98.9%. The bottom of the column yielded extract B1 at a flow rate of 248.47 kmol / h, with a m-cresol extraction rate of 99.7%. Extract B1 entered flash evaporator F1 and was flashed at 0.1 atm and 180 °C. The top of the flash evaporator yielded a neutral oil-rich fraction D2 with a flow rate of 47.70 kmol / h and a neutral oil content of 82.0%. The bottom of the flash evaporator yielded a neutral oil-removed extract B2, which entered flash evaporator F2 and was flashed at 0.1 atm and 225 °C. The top of the flash evaporator yielded a phenol-rich fraction D3 with a flow rate of 67.10 kmol / h. Gas chromatography analysis showed that the m-cresol content was 81.9% and the neutral oil content was 5.1%. The phenol-rich fraction D3 enters distillation column T2, which has 40 trays, with the feed tray being the 20th tray, and a reflux ratio of 4. After distillation, the lowest azeotrope D4, consisting of tetrahydronaphthalene, undecane, and m-cresol, is obtained at the top of the column with a flow rate of 8.28 kmol / h. The bottom fraction, m-cresol and triethylene glycol effluent B4, containing phenol and a small amount of hydrogen bond donors, is obtained at a flow rate of 58.82 kmol / h. B4 enters the recovery distillation column T3, which also has 40 trays, with the feed tray being the 20th tray, and a reflux ratio of 4. After distillation, the top fraction yields m-cresol product with a flow rate of 50.1 kmol / h and a purity of 99.9%, while the bottom fraction, triethylene glycol effluent (hydrogen bond donor B5), is obtained at a flow rate of 8.72 kmol / h and is recycled after being mixed with B3.

[0025] Example 2

[0026] In this embodiment, an extractive distillation separation experiment was conducted using a simulated oleophenol mixture that can form an azeotrope. The oleophenol mixture used was a mixture containing 40% m-cresol, 40% tetrahydronaphthalene, and 20% undecane, wherein tetrahydronaphthalene and undecane were neutral oil components. The hydrogen bond acceptor betaine and the hydrogen bond donor tetraethylene glycol were mixed at a molar ratio of 1:4 and magnetically stirred at 90°C for 6 hours to ensure complete reaction, yielding a eutectic solvent extractant. A eutectic solvent extractant with a flow rate of 100 kmol / h was introduced from the top of extraction column T1, while the oleophenol mixture feedstock with a flow rate of 250 kmol / h was introduced from the bottom of the extraction column (the molar ratio of extractant to intermediate cresol in the feedstock was 1:1). Countercurrent contact extraction was carried out in extraction column T1 at a temperature of 25°C and a pressure of 1 atm. The top of the column yielded raffinate D1 (removed phenol oil) at a flow rate of 102.23 kmol / h, with a neutral oil content of 98.9%. The bottom of the column yielded extract B1 at a flow rate of 247.77 kmol / h, with a m-cresol extraction rate of 99.7%. Extract B1 entered flash evaporator F1 and was flashed at 0.1 atm and 180 °C. The top of the flash evaporator yielded a neutral oil-rich fraction D2 with a flow rate of 47.29 kmol / h and a neutral oil content of 82.0%. The bottom of the flash evaporator yielded a neutral oil-removed extract B2, which entered flash evaporator F2 and was flashed at 0.1 atm and 225 °C. The top of the flash evaporator yielded a phenol-rich fraction D3 with a flow rate of 66.69 kmol / h. Gas chromatography analysis showed that the m-cresol content was 81.9% and the neutral oil content was 5.1%. The phenol-rich fraction D3 enters distillation column T2, which has 40 trays, with the feed tray being the 20th tray, and a reflux ratio of 4. After distillation, the top of the column yields the lowest azeotrope D4 of tetrahydronaphthalene, undecane, and m-cresol at a flow rate of 8.23 ​​kmol / h. The bottom of the column yields m-cresol and tetraethylene glycol distillate B4 at a flow rate of 58.46 kmol / h, containing phenol and a small amount of hydrogen bond donors. B4 enters the recovery distillation column T3, which also has 40 trays, with the feed tray being the 20th tray, and a reflux ratio of 4. After distillation, the top of the column yields m-cresol at a flow rate of 49.79 kmol / h with a purity of 99.9%, and the bottom of the column yields tetraethylene glycol distillate at a flow rate of 8.67 kmol / h, which is the hydrogen bond donor B5. This distillate is mixed with B3 and recycled.

[0027] Example 3

[0028] In this embodiment, an extractive distillation separation experiment was conducted using a simulated oleophenol mixture that can form an azeotrope. The oleophenol mixture used was a mixture containing 40% m-cresol, 40% tetrahydronaphthalene, and 20% undecane, wherein tetrahydronaphthalene and undecane were neutral oil components. L-carnitine (hydrogen bond acceptor) and triethylene glycol (hydrogen bond donor) were mixed at a molar ratio of 1:4 and magnetically stirred at 90°C for 6 hours to ensure complete reaction, yielding a eutectic solvent extractant. A eutectic solvent extractant with a flow rate of 100 kmol / h was introduced from the top of extraction column T1, while the oleophenol mixture feedstock with a flow rate of 250 kmol / h was introduced from the bottom of the extraction column (the molar ratio of extractant to intermediate cresol in the feedstock was 1:1). Countercurrent contact extraction was carried out in extraction column T1 at a temperature of 25°C and a pressure of 1 atm. The top of the column yielded raffinate D1 (removed phenol oil) at a flow rate of 99.93 kmol / h, with a neutral oil content of 98.8%. The bottom of the column yielded extract B1 at a flow rate of 250.07 kmol / h, with a m-cresol extraction rate of 99.7%. Extract B1 entered flash evaporator F1 and was flashed at 0.1 atm and 180 °C. The top of the flash evaporator yielded a neutral oil-rich fraction D2 at a flow rate of 48.12 kmol / h, containing a neutral oil content of 83.0%. The bottom of the flash evaporator yielded a neutral oil-removed extract B2, which entered flash evaporator F2 and was flashed at 0.1 atm and 225 °C. The top of the flash evaporator yielded a phenol-rich fraction D3 at a flow rate of 67.91 kmol / h. Gas chromatography analysis showed that the m-cresol content was 81.8% and the neutral oil content was 5.3%. The phenol-rich fraction D3 enters distillation column T2, which has 40 trays, with the feed tray being the 20th tray, and a reflux ratio of 4. After distillation, the lowest azeotrope D4, consisting of tetrahydronaphthalene, undecane, and m-cresol, is obtained at the top of the column with a flow rate of 8.71 kmol / h. The bottom fraction, m-cresol and triethylene glycol, is obtained as a distillate B4, containing phenol and a small amount of hydrogen bond donors, with a flow rate of 59.20 kmol / h. B4 enters recovery distillation column T3, which also has 40 trays, with the feed tray being the 20th tray, and a reflux ratio of 4. After distillation, the top fraction yields m-cresol with a flow rate of 50.44 kmol / h and a purity of 99.9%, while the bottom fraction, triethylene glycol (the hydrogen bond donor B5), is obtained with a flow rate of 8.76 kmol / h and is recycled after being mixed with B3.

[0029] Example 4

[0030] In this embodiment, an extractive distillation separation experiment was conducted using a simulated oleophenol mixture that can form an azeotrope. The oleophenol mixture used was a mixture containing 40% m-cresol, 40% tetrahydronaphthalene, and 20% undecane, wherein tetrahydronaphthalene and undecane were neutral oil components. L-carnitine (hydrogen bond acceptor) and tetraethylene glycol (hydrogen bond donor) were mixed at a molar ratio of 1:4 and magnetically stirred at 90°C for 6 hours to ensure complete reaction, yielding a eutectic solvent extractant. A eutectic solvent extractant with a flow rate of 100 kmol / h was introduced from the top of extraction column T1, while the oleophenol mixture feedstock with a flow rate of 250 kmol / h was introduced from the bottom of the extraction column (the molar ratio of extractant to intermediate cresol in the feedstock was 1:1). Countercurrent contact extraction was carried out in extraction column T1 at a temperature of 25°C and a pressure of 1 atm. The top of the column yielded raffinate D1 (removed phenol oil) at a flow rate of 101.31 kmol / h, with a neutral oil content of 98.9%. The bottom of the column yielded extract B1 at a flow rate of 248.69 kmol / h, with a m-cresol extraction rate of 99.7%. Extract B1 entered flash evaporator F1 and was flashed at 0.1 atm and 180 °C. The top of the flash evaporator yielded a neutral oil-rich fraction D2 at a flow rate of 47.75 kmol / h, containing a neutral oil content of 83.0%. The bottom of the flash evaporator yielded a neutral oil-removed extract B2, which entered flash evaporator F2 and was flashed at 0.1 atm and 225 °C. The top of the flash evaporator yielded a phenol-rich fraction D3 at a flow rate of 67.55 kmol / h. Gas chromatography analysis showed that the m-cresol content was 81.9% and the neutral oil content was 5.1%. The phenol-rich fraction D3 enters distillation column T2, which has 40 trays, with the feed tray being the 20th tray, and a reflux ratio of 4. After distillation, the top of the column yields the lowest azeotrope D4 of tetrahydronaphthalene, undecane, and m-cresol at a flow rate of 8.33 kmol / h. The bottom of the column yields m-cresol and tetraethylene glycol distillate B4 at a flow rate of 59.22 kmol / h, containing phenol and a small amount of hydrogen bond donors. B4 enters the recovery distillation column T3, which also has 40 trays, with the feed tray being the 20th tray, and a reflux ratio of 4. After distillation, the top of the column yields m-cresol at a flow rate of 50.44 kmol / h with a purity of 99.9%, and the bottom of the column yields tetraethylene glycol distillate at a flow rate of 8.78 kmol / h, which is the hydrogen bond donor B5. This distillate is mixed with B3 and recycled.

[0031] Example 5

[0032] In this embodiment, an extractive distillation separation experiment was conducted using a simulated oleophenol mixture that can form an azeotrope. The oleophenol mixture used was a mixture containing 40% m-cresol, 40% tetrahydronaphthalene, and 20% undecane, wherein tetrahydronaphthalene and undecane were neutral oil components. L-carnitine (hydrogen bond acceptor) and triethylene glycol (hydrogen bond donor) were mixed at a molar ratio of 1:3.3 and magnetically stirred at 90°C for 6 hours to ensure complete reaction, yielding a eutectic solvent extractant. A eutectic solvent extractant with a flow rate of 100 kmol / h was introduced from the top of extraction column T1, while the oleophenol mixture feedstock with a flow rate of 250 kmol / h was introduced from the bottom of the extraction column (the molar ratio of extractant to intermediate cresol in the feedstock was 1:1). Countercurrent contact extraction was carried out in extraction column T1 at a temperature of 25°C and a pressure of 1 atm. The top of the column yielded raffinate D1 (removed phenol oil) at a flow rate of 99.49 kmol / h, with a neutral oil content of 98.7%. The bottom of the column yielded extract B1 at a flow rate of 250.51 kmol / h, with a m-cresol extraction rate of 99.8%. Extract B1 entered flash evaporator F1 and was flashed at 0.1 atm and 180 °C. The top of the flash evaporator yielded a neutral oil-rich fraction D2 at a flow rate of 49.05 kmol / h, containing a neutral oil content of 83.0%. The bottom of the flash evaporator yielded a neutral oil-removed extract B2, which entered flash evaporator F2 and was flashed at 0.1 atm and 225 °C. The top of the flash evaporator yielded a phenol-rich fraction D3 at a flow rate of 69.19 kmol / h. Gas chromatography analysis showed that the m-cresol content was 81.2% and the neutral oil content was 5.7%. The phenol-rich fraction D3 enters distillation column T2, which has 40 trays, with the feed tray being the 20th tray, and a reflux ratio of 4. After distillation, the lowest azeotrope D4, consisting of tetrahydronaphthalene, undecane, and m-cresol, is obtained at the top of the column with a flow rate of 9.54 kmol / h. The bottom fraction, m-cresol and triethylene glycol effluent B4, containing phenol and a small amount of hydrogen bond donors, is obtained at a flow rate of 59.65 kmol / h. B4 enters recovery distillation column T3, which also has 40 trays, with the feed tray being the 20th tray, and a reflux ratio of 4. After distillation, the top fraction yields m-cresol product with a flow rate of 50.59 kmol / h and a purity of 99.9%, while the bottom fraction, triethylene glycol effluent (hydrogen bond donor B5), is obtained at a flow rate of 9.06 kmol / h and is recycled after being mixed with B3.

[0033] Example 6

[0034] In this embodiment, an extractive distillation separation experiment was conducted using a simulated oleophenol mixture that can form an azeotrope. The oleophenol mixture used was a mixture containing 40% m-cresol, 40% tetrahydronaphthalene, and 20% undecane, wherein tetrahydronaphthalene and undecane were neutral oil components. L-carnitine (hydrogen bond acceptor) and triethylene glycol (hydrogen bond donor) were mixed at a molar ratio of 1:3.3 and magnetically stirred at 90°C for 6 hours to ensure complete reaction, yielding a eutectic solvent extractant. A eutectic solvent extractant with a flow rate of 100 kmol / h was introduced from the top of extraction column T1, while the oleophenol mixture feedstock with a flow rate of 250 kmol / h was introduced from the bottom of the extraction column (the molar ratio of extractant to intermediate cresol in the feedstock was 1:1). Countercurrent contact extraction was carried out in extraction column T1 at a temperature of 25°C and a pressure of 1 atm. The top of the column yielded raffinate D1 (removed phenol oil) at a flow rate of 109.66 kmol / h, with a neutral oil content of 99.0%. The bottom of the column yielded extract B1 at a flow rate of 200.34 kmol / h, with a m-cresol extraction rate of 99.4%. Extract B1 entered flash evaporator F1 and was flashed at 0.1 atm and 180 °C. The top of the flash evaporator yielded a neutral oil-rich fraction D2 at a flow rate of 45.05 kmol / h, containing a neutral oil content of 83.0%. The bottom of the flash evaporator yielded a neutral oil-removed extract B2, which entered flash evaporator F2 and was flashed at 0.1 atm and 225 °C. The top of the flash evaporator yielded a phenol-rich fraction D3 at a flow rate of 55.06 kmol / h. Gas chromatography analysis showed that the m-cresol content was 75.9% and the neutral oil content was 6.8%. The phenol-rich fraction D3 enters distillation column T2, which has 40 trays, with the feed tray being the 20th tray, and a reflux ratio of 4. After distillation, the lowest azeotrope D4, consisting of tetrahydronaphthalene, undecane, and m-cresol, is obtained at the top of the column with a flow rate of 9.06 kmol / h. The bottom fraction, m-cresol and triethylene glycol effluent B4, containing phenol and a small amount of hydrogen bond donors, is obtained at a flow rate of 46.0 kmol / h. B4 enters recovery distillation column T3, which also has 40 trays, with the feed tray being the 20th tray, and a reflux ratio of 4. After distillation, the top fraction yields m-cresol product with a flow rate of 36.47 kmol / h and a purity of 99.9%, while the bottom fraction, triethylene glycol effluent (hydrogen bond donor B5), is obtained at a flow rate of 9.53 kmol / h and is recycled after being mixed with B3.

[0035] Example 7

[0036] In this embodiment, an extractive distillation separation experiment was conducted using a simulated oleophenol mixture that can form an azeotrope. The oleophenol mixture used was a mixture containing 40% m-cresol, 40% tetrahydronaphthalene, and 20% undecane, wherein tetrahydronaphthalene and undecane were neutral oil components. L-carnitine (hydrogen bond acceptor) and triethylene glycol (hydrogen bond donor) were mixed at a molar ratio of 1:3.3 and magnetically stirred at 90°C for 6 hours to ensure complete reaction, yielding a eutectic solvent extractant. A eutectic solvent extractant with a flow rate of 100 kmol / h was introduced from the top of extraction column T1, while the oleophenol mixture feedstock with a flow rate of 250 kmol / h was introduced from the bottom of the extraction column (the molar ratio of extractant to intermediate cresol in the feedstock was 1:1). Countercurrent contact extraction was carried out in extraction column T1 at a temperature of 25°C and a pressure of 1 atm. The top of the column yielded raffinate D1 (removed phenol oil) at a flow rate of 101.64 kmol / h, with a neutral oil content of 99.0%. The bottom of the column yielded extract B1 at a flow rate of 248.36 kmol / h, with a m-cresol extraction rate of 99.7%. Extract B1 entered flash evaporator F1 and was flashed at 0.1 atm and 180 °C. The top of the flash evaporator yielded a neutral oil-rich fraction D2 with a flow rate of 47.00 kmol / h and a neutral oil content of 83.6%. The bottom of the flash evaporator yielded a neutral oil-removed extract B2, which entered flash evaporator F2 and was flashed at 0.1 atm and 225 °C. The top of the flash evaporator yielded a phenol-rich fraction D3 with a flow rate of 67.00 kmol / h. Gas chromatography analysis showed that the m-cresol content was 82.0% and the neutral oil content was 5.4%. The phenol-rich fraction D3 enters distillation column T2, which has 40 trays, with the feed tray being the 20th tray, and a reflux ratio of 4. After distillation, the lowest azeotrope D4, consisting of tetrahydronaphthalene, undecane, and m-cresol, is obtained at the top of the column with a flow rate of 8.75 kmol / h. The bottom fraction, m-cresol and triethylene glycol effluent B4, containing phenol and a small amount of hydrogen bond donors, is obtained at a flow rate of 58.25 kmol / h. B4 enters recovery distillation column T3, which also has 40 trays, with the feed tray being the 20th tray, and a reflux ratio of 4. After distillation, the top fraction yields m-cresol product with a flow rate of 49.81 kmol / h and a purity of 99.9%, while the bottom fraction, triethylene glycol effluent (hydrogen bond donor B5), is obtained at a flow rate of 8.44 kmol / h and is recycled after being mixed with B3.

[0037] Example 8

[0038] In this embodiment, an extractive distillation separation experiment was conducted using a simulated oleophenol mixture that can form an azeotrope. The oleophenol mixture used was a mixture containing 40% m-cresol, 40% tetrahydronaphthalene, and 20% undecane, wherein tetrahydronaphthalene and undecane were neutral oil components. L-carnitine (hydrogen bond acceptor) and triethylene glycol (hydrogen bond donor) were mixed at a molar ratio of 1:3.3 and magnetically stirred at 90°C for 6 hours to ensure complete reaction, yielding a eutectic solvent extractant. A eutectic solvent extractant with a flow rate of 100 kmol / h was introduced from the top of extraction column T1, while the oleophenol mixture feedstock with a flow rate of 250 kmol / h was introduced from the bottom of the extraction column (the molar ratio of extractant to intermediate cresol in the feedstock was 1:1). Countercurrent contact extraction was carried out in extraction column T1 at a temperature of 25°C and a pressure of 1 atm. The top of the column yielded raffinate D1 (removed phenol oil) at a flow rate of 99.49 kmol / h, with a neutral oil content of 98.7%. The bottom of the column yielded extract B1 at a flow rate of 250.51 kmol / h, with a m-cresol extraction rate of 99.8%. Extract B1 entered flash evaporator F1 and was flashed at 0.05 atm and 150 °C. The top of the flash evaporator yielded a neutral oil-rich fraction D2 at a flow rate of 52.41 kmol / h, containing a neutral oil content of 84.0%. The bottom of the flash evaporator yielded a neutral oil-removed extract B2, which entered flash evaporator F2 and was flashed at 0.1 atm and 225 °C. The top of the flash evaporator yielded a phenol-rich fraction D3 at a flow rate of 67.22 kmol / h. Gas chromatography analysis showed that the m-cresol content was 82.1% and the neutral oil content was 5.4%. The phenol-rich fraction D3 enters distillation column T2, which has 40 trays, with the feed tray being the 20th tray, and a reflux ratio of 4. After distillation, the lowest azeotrope D4, consisting of tetrahydronaphthalene, undecane, and m-cresol, is obtained at the top of the column with a flow rate of 8.78 kmol / h. The bottom fraction, m-cresol and triethylene glycol effluent B4, containing phenol and a small amount of hydrogen bond donors, is obtained at a flow rate of 58.44 kmol / h. B4 enters the recovery distillation column T3, which also has 40 trays, with the feed tray being the 20th tray, and a reflux ratio of 4. After distillation, the top fraction yields m-cresol product with a flow rate of 50.54 kmol / h and a purity of 99.9%, while the bottom fraction, triethylene glycol effluent (hydrogen bond donor B5), is obtained at a flow rate of 8.40 kmol / h and is recycled after being mixed with B3.

[0039] Example 9

[0040] In this embodiment, an extractive distillation separation experiment was conducted using a simulated oleophenol mixture that can form an azeotrope. The oleophenol mixture used was a mixture containing 40% m-cresol, 40% tetrahydronaphthalene, and 20% undecane, wherein tetrahydronaphthalene and undecane were neutral oil components. L-carnitine (hydrogen bond acceptor) and triethylene glycol (hydrogen bond donor) were mixed at a molar ratio of 1:3.3 and magnetically stirred at 90°C for 6 hours to ensure complete reaction, yielding a eutectic solvent extractant. A eutectic solvent extractant with a flow rate of 100 kmol / h was introduced from the top of extraction column T1, while the oleophenol mixture feedstock with a flow rate of 250 kmol / h was introduced from the bottom of the extraction column (the molar ratio of extractant to intermediate cresol in the feedstock was 1:1). Countercurrent contact extraction was carried out in extraction column T1 at a temperature of 25°C and a pressure of 1 atm. The top of the column yielded raffinate D1 (removed phenol oil) at a flow rate of 99.49 kmol / h, with a neutral oil content of 98.7%. The bottom of the column yielded extract B1 at a flow rate of 250.51 kmol / h, with a m-cresol extraction rate of 99.8%. Extract B1 entered flash evaporator F1 and was flashed at 0.1 atm and 180°C. The top of the flash evaporator yielded a neutral oil-rich fraction D2 at a flow rate of 49.05 kmol / h, containing a neutral oil content of 83.0%. The bottom of the flash evaporator yielded a neutral oil-removed extract B2, which entered flash evaporator F2 and was flashed at 0.05 atm and 200°C. The top of the flash evaporator yielded a phenol-rich fraction D3 at a flow rate of 71.94 kmol / h. Gas chromatography analysis showed that the m-cresol content was 79.8% and the neutral oil content was 5.8%. The phenol-rich fraction D3 enters distillation column T2, which has 40 trays, with the feed tray being the 20th tray, and a reflux ratio of 4. After distillation, the lowest azeotrope D4, consisting of tetrahydronaphthalene, undecane, and m-cresol, is obtained at the top of the column with a flow rate of 10.09 kmol / h. The bottom fraction, m-cresol and triethylene glycol effluent B4, containing phenol and a small amount of hydrogen bond donors, is obtained at a flow rate of 61.85 kmol / h. B4 enters the recovery distillation column T3, which also has 40 trays, with the feed tray being the 20th tray, and a reflux ratio of 4. After distillation, the top fraction yields m-cresol product with a flow rate of 51.49 kmol / h and a purity of 99.9%, while the bottom fraction, triethylene glycol effluent (hydrogen bond donor B5), is obtained at a flow rate of 10.36 kmol / h and is recycled after being mixed with B3.

[0041] Example 10

[0042] In this embodiment, an extractive distillation separation experiment was conducted using a simulated oleophenol mixture that can form an azeotrope. The oleophenol mixture used was a mixture containing 40% m-cresol, 40% tetrahydronaphthalene, and 20% undecane, wherein tetrahydronaphthalene and undecane were neutral oil components. L-carnitine (hydrogen bond acceptor) and triethylene glycol (hydrogen bond donor) were mixed at a molar ratio of 1:3.3 and magnetically stirred at 90°C for 6 hours to ensure complete reaction, yielding a eutectic solvent extractant. A eutectic solvent extractant with a flow rate of 100 kmol / h was introduced from the top of extraction column T1, while the oleophenol mixture feedstock with a flow rate of 250 kmol / h was introduced from the bottom of the extraction column (the molar ratio of extractant to intermediate cresol in the feedstock was 1:1). Countercurrent contact extraction was carried out in extraction column T1 at a temperature of 25°C and a pressure of 1 atm. The top of the column yielded raffinate D1 (removed phenol oil) at a flow rate of 99.49 kmol / h, with a neutral oil content of 98.7%. The bottom of the column yielded extract B1 at a flow rate of 250.51 kmol / h, with a m-cresol extraction rate of 99.8%. Extract B1 entered flash evaporator F1 and was flashed at 0.1 atm and 180 °C. The top of the flash evaporator yielded a neutral oil-rich fraction D2 with a flow rate of 49.05 kmol / h and a neutral oil content of 83.0%. The bottom of the flash evaporator yielded a neutral oil-removed extract B2, which entered flash evaporator F2 and was flashed at 0.1 atm and 200 °C. The top of the flash evaporator yielded a phenol-rich fraction D3 with a flow rate of 34.66 kmol / h. Gas chromatography analysis showed that the m-cresol content was 74.6% and the neutral oil content was 19.0%. The phenol-rich fraction D3 enters distillation column T2, which has 40 trays, with the feed tray being the 20th tray, and a reflux ratio of 4. After distillation, the lowest azeotrope D4, consisting of tetrahydronaphthalene, undecane, and m-cresol, is obtained at the top of the column with a flow rate of 15.93 kmol / h. The bottom fraction, m-cresol and triethylene glycol effluent B4, containing phenol and a small amount of hydrogen bond donors, is obtained at a flow rate of 18.73 kmol / h. B4 enters the recovery distillation column T3, which also has 40 trays, with the feed tray being the 20th tray, and a reflux ratio of 4. After distillation, the top fraction yields m-cresol product with a flow rate of 16.51 kmol / h and a purity of 99.7%, while the bottom fraction, triethylene glycol effluent (hydrogen bond donor B5), is obtained at a flow rate of 2.22 kmol / h and is recycled after being mixed with B3.

[0043] Example 11

[0044] In this embodiment, an extractive distillation separation experiment was conducted using a simulated oleophenol mixture that can form an azeotrope. The oleophenol mixture used was a mixture containing 40% m-cresol, 40% tetrahydronaphthalene, and 20% undecane, wherein tetrahydronaphthalene and undecane were neutral oil components. L-carnitine (hydrogen bond acceptor) and triethylene glycol (hydrogen bond donor) were mixed at a molar ratio of 1:3.3 and magnetically stirred at 90°C for 6 hours to ensure complete reaction, yielding a eutectic solvent extractant. A eutectic solvent extractant with a flow rate of 100 kmol / h was introduced from the top of extraction column T1, while the oleophenol mixture feedstock with a flow rate of 250 kmol / h was introduced from the bottom of the extraction column (the molar ratio of extractant to intermediate cresol in the feedstock was 1:1). Countercurrent contact extraction was carried out in extraction column T1 at a temperature of 25°C and a pressure of 1 atm. The top of the column yielded raffinate D1 (removed phenol oil) at a flow rate of 99.49 kmol / h, with a neutral oil content of 98.7%. The bottom of the column yielded extract B1 at a flow rate of 250.51 kmol / h, with a m-cresol extraction rate of 99.8%. Extract B1 entered flash evaporator F1 and was flashed at 0.1 atm and 180 °C. The top of the flash evaporator yielded a neutral oil-rich fraction D2 at a flow rate of 49.05 kmol / h, containing a neutral oil content of 83.0%. The bottom of the flash evaporator yielded a neutral oil-removed extract B2, which entered flash evaporator F2 and was flashed at 0.1 atm and 225 °C. The top of the flash evaporator yielded a phenol-rich fraction D3 at a flow rate of 69.19 kmol / h. Gas chromatography analysis showed that the m-cresol content was 81.2% and the neutral oil content was 5.7%. The phenol-rich fraction D3 enters distillation column T2, which has 30 trays, with the feed tray being the 20th tray, and a reflux ratio of 4. After distillation, the lowest azeotrope D4, consisting of tetrahydronaphthalene, undecane, and m-cresol, is obtained at the top of the column with a flow rate of 9.23 kmol / h. The bottom fraction, m-cresol and triethylene glycol effluent B4, containing phenol and a small amount of hydrogen bond donors, is obtained at a flow rate of 59.96 kmol / h. B4 enters the recovery distillation column T3, which has 40 trays, with the feed tray being the 20th tray, and a reflux ratio of 4. After distillation, the top fraction yields m-cresol product with a flow rate of 50.90 kmol / h and a purity of 99.8%, while the bottom fraction, triethylene glycol effluent (hydrogen bond donor B5), is obtained at a flow rate of 9.06 kmol / h and is recycled after being mixed with B3.

[0045] Example 12

[0046] In this embodiment, an extractive distillation separation experiment was conducted using a simulated oleophenol mixture that can form an azeotrope. The oleophenol mixture used was a mixture containing 40% m-cresol, 40% tetrahydronaphthalene, and 20% undecane, wherein tetrahydronaphthalene and undecane were neutral oil components. L-carnitine (hydrogen bond acceptor) and triethylene glycol (hydrogen bond donor) were mixed at a molar ratio of 1:3.3 and magnetically stirred at 90°C for 6 hours to ensure complete reaction, yielding a eutectic solvent extractant. A eutectic solvent extractant with a flow rate of 100 kmol / h was introduced from the top of extraction column T1, while the oleophenol mixture feedstock with a flow rate of 250 kmol / h was introduced from the bottom of the extraction column (the molar ratio of extractant to intermediate cresol in the feedstock was 1:1). Countercurrent contact extraction was carried out in extraction column T1 at a temperature of 25°C and a pressure of 1 atm. The top of the column yielded raffinate D1 (removed phenol oil) at a flow rate of 99.49 kmol / h, with a neutral oil content of 98.7%. The bottom of the column yielded extract B1 at a flow rate of 250.51 kmol / h, with a m-cresol extraction rate of 99.8%. Extract B1 entered flash evaporator F1 and was flashed at 0.1 atm and 180 °C. The top of the flash evaporator yielded a neutral oil-rich fraction D2 at a flow rate of 49.05 kmol / h, containing a neutral oil content of 83.0%. The bottom of the flash evaporator yielded a neutral oil-removed extract B2, which entered flash evaporator F2 and was flashed at 0.1 atm and 225 °C. The top of the flash evaporator yielded a phenol-rich fraction D3 at a flow rate of 69.19 kmol / h. Gas chromatography analysis showed that the m-cresol content was 81.2% and the neutral oil content was 5.7%. The phenol-rich fraction D3 enters distillation column T2, which has 40 trays, with the feed tray being the 30th tray, and a reflux ratio of 4. After distillation, the lowest azeotrope D4, consisting of tetrahydronaphthalene, undecane, and m-cresol, is obtained at the top of the column with a flow rate of 9.41 kmol / h. The bottom fraction, m-cresol and triethylene glycol effluent B4, containing phenol and a small amount of hydrogen bond donors, is obtained at a flow rate of 59.78 kmol / h. B4 enters the recovery distillation column T3, which also has 40 trays, with the feed tray being the 20th tray, and a reflux ratio of 4. After distillation, the top fraction yields m-cresol product with a flow rate of 50.72 kmol / h and a purity of 99.9%, while the bottom fraction, triethylene glycol effluent (hydrogen bond donor B5), is obtained at a flow rate of 9.06 kmol / h and is recycled after being mixed with B3.

[0047] Example 13

[0048] In this embodiment, an extractive distillation separation experiment was conducted using a simulated oleophenol mixture that can form an azeotrope. The oleophenol mixture used was a mixture containing 40% m-cresol, 40% tetrahydronaphthalene, and 20% undecane, wherein tetrahydronaphthalene and undecane were neutral oil components. L-carnitine (hydrogen bond acceptor) and triethylene glycol (hydrogen bond donor) were mixed at a molar ratio of 1:3.3 and magnetically stirred at 90°C for 6 hours to ensure complete reaction, yielding a eutectic solvent extractant. A eutectic solvent extractant with a flow rate of 100 kmol / h was introduced from the top of extraction column T1, while the oleophenol mixture feedstock with a flow rate of 250 kmol / h was introduced from the bottom of the extraction column (the molar ratio of extractant to intermediate cresol in the feedstock was 1:1). Countercurrent contact extraction was carried out in extraction column T1 at a temperature of 25°C and a pressure of 1 atm. The top of the column yielded raffinate D1 (removed phenol oil) at a flow rate of 99.49 kmol / h, with a neutral oil content of 98.7%. The bottom of the column yielded extract B1 at a flow rate of 250.51 kmol / h, with a m-cresol extraction rate of 99.8%. Extract B1 entered flash evaporator F1 and was flashed at 0.1 atm and 180 °C. The top of the flash evaporator yielded a neutral oil-rich fraction D2 at a flow rate of 49.05 kmol / h, containing a neutral oil content of 83.0%. The bottom of the flash evaporator yielded a neutral oil-removed extract B2, which entered flash evaporator F2 and was flashed at 0.1 atm and 225 °C. The top of the flash evaporator yielded a phenol-rich fraction D3 at a flow rate of 69.19 kmol / h. Gas chromatography analysis showed that the m-cresol content was 81.2% and the neutral oil content was 5.7%. The phenol-rich fraction D3 enters distillation column T2, which has 40 trays, with the feed tray being the 20th tray, and a reflux ratio of 1. After distillation, the lowest azeotrope D4, consisting of tetrahydronaphthalene, undecane, and m-cresol, is obtained at the top of the column with a flow rate of 6.90 kmol / h. The bottom fraction, m-cresol and triethylene glycol effluent B4, containing phenol and a small amount of hydrogen bond donors, is obtained at a flow rate of 62.29 kmol / h. B4 enters the recovery distillation column T3, which also has 40 trays, with the feed tray being the 20th tray, and a reflux ratio of 4. After distillation, the top fraction yields m-cresol product with a flow rate of 53.23 kmol / h and a purity of 99.8%, while the bottom fraction, triethylene glycol effluent (hydrogen bond donor B5), is obtained at a flow rate of 9.06 kmol / h and is recycled after being mixed with B3.

[0049] Example 14

[0050] In this embodiment, an extractive distillation separation experiment was conducted using a simulated oleophenol mixture that can form an azeotrope. The oleophenol mixture used was a mixture containing 40% m-cresol, 40% tetrahydronaphthalene, and 20% undecane, wherein tetrahydronaphthalene and undecane were neutral oil components. L-carnitine (hydrogen bond acceptor) and triethylene glycol (hydrogen bond donor) were mixed at a molar ratio of 1:3.3 and magnetically stirred at 90°C for 6 hours to ensure complete reaction, yielding a eutectic solvent extractant. A eutectic solvent extractant with a flow rate of 100 kmol / h was introduced from the top of extraction column T1, while the oleophenol mixture feedstock with a flow rate of 250 kmol / h was introduced from the bottom of the extraction column (the molar ratio of extractant to intermediate cresol in the feedstock was 1:1). Countercurrent contact extraction was carried out in extraction column T1 at a temperature of 25°C and a pressure of 1 atm. The top of the column yielded raffinate D1 (removed phenol oil) at a flow rate of 99.49 kmol / h, with a neutral oil content of 98.7%. The bottom of the column yielded extract B1 at a flow rate of 250.51 kmol / h, with a m-cresol extraction rate of 99.8%. Extract B1 entered flash evaporator F1 and was flashed at 0.1 atm and 180 °C. The top of the flash evaporator yielded a neutral oil-rich fraction D2 at a flow rate of 49.05 kmol / h, containing a neutral oil content of 83.0%. The bottom of the flash evaporator yielded a neutral oil-removed extract B2, which entered flash evaporator F2 and was flashed at 0.1 atm and 225 °C. The top of the flash evaporator yielded a phenol-rich fraction D3 at a flow rate of 69.19 kmol / h. Gas chromatography analysis showed that the m-cresol content was 81.2% and the neutral oil content was 5.7%. The phenol-rich fraction D3 enters distillation column T2, which has 40 trays, with the feed tray being the 20th tray, and a reflux ratio of 4. After distillation, the lowest azeotrope D4, consisting of tetrahydronaphthalene, undecane, and m-cresol, is obtained at the top of the column with a flow rate of 9.54 kmol / h. The bottom fraction, m-cresol and triethylene glycol effluent B4, containing phenol and a small amount of hydrogen bond donors, is obtained at a flow rate of 59.65 kmol / h. B4 enters recovery distillation column T3, which has 30 trays, with the feed tray being the 20th tray, and a reflux ratio of 4. After distillation, the top fraction yields m-cresol product with a flow rate of 48.96 kmol / h and a purity of 99.8%, while the bottom fraction, triethylene glycol effluent (hydrogen bond donor B5), is obtained at a flow rate of 10.69 kmol / h and is recycled after being mixed with B3.

[0051] Example 15

[0052] In this embodiment, an extractive distillation separation experiment was conducted using a simulated oleophenol mixture that can form an azeotrope. The oleophenol mixture used was a mixture containing 40% m-cresol, 40% tetrahydronaphthalene, and 20% undecane, wherein tetrahydronaphthalene and undecane were neutral oil components. L-carnitine (hydrogen bond acceptor) and triethylene glycol (hydrogen bond donor) were mixed at a molar ratio of 1:3.3 and magnetically stirred at 90°C for 6 hours to ensure complete reaction, yielding a eutectic solvent extractant. A eutectic solvent extractant with a flow rate of 100 kmol / h was introduced from the top of extraction column T1, while the oleophenol mixture feedstock with a flow rate of 250 kmol / h was introduced from the bottom of the extraction column (the molar ratio of extractant to intermediate cresol in the feedstock was 1:1). Countercurrent contact extraction was carried out in extraction column T1 at a temperature of 25°C and a pressure of 1 atm. The top of the column yielded raffinate D1 (removed phenol oil) at a flow rate of 99.49 kmol / h, with a neutral oil content of 98.7%. The bottom of the column yielded extract B1 at a flow rate of 250.51 kmol / h, with a m-cresol extraction rate of 99.8%. Extract B1 entered flash evaporator F1 and was flashed at 0.1 atm and 180 °C. The top of the flash evaporator yielded a neutral oil-rich fraction D2 at a flow rate of 49.05 kmol / h, containing a neutral oil content of 83.0%. The bottom of the flash evaporator yielded a neutral oil-removed extract B2, which entered flash evaporator F2 and was flashed at 0.1 atm and 225 °C. The top of the flash evaporator yielded a phenol-rich fraction D3 at a flow rate of 69.19 kmol / h. Gas chromatography analysis showed that the m-cresol content was 81.2% and the neutral oil content was 5.7%. The phenol-rich fraction D3 enters distillation column T2, which has 30 trays, with the feed tray being the 20th tray, and a reflux ratio of 4. After distillation, the top of the column yields the lowest azeotrope D4 of tetrahydronaphthalene, undecane, and m-cresol at a flow rate of 9.54 kmol / h. The bottom of the column yields m-cresol and triethylene glycol effluent B4 at a flow rate of 59.65 kmol / h, containing phenol and a small amount of hydrogen bond donors. B4 enters the recovery distillation column T3, which has 40 trays, with the feed tray being the 30th tray, and a reflux ratio of 4. After distillation, the top of the column yields m-cresol at a flow rate of 49.53 kmol / h with a purity of 99.9%, and the bottom of the column yields triethylene glycol effluent at a flow rate of 10.12 kmol / h, i.e., the hydrogen bond donor B5, which is mixed with B3 and recycled.

[0053] Example 16

[0054] In this embodiment, an extractive distillation separation experiment was conducted using a simulated oleophenol mixture that can form an azeotrope. The oleophenol mixture used was a mixture containing 40% m-cresol, 40% tetrahydronaphthalene, and 20% undecane, wherein tetrahydronaphthalene and undecane were neutral oil components. L-carnitine (hydrogen bond acceptor) and triethylene glycol (hydrogen bond donor) were mixed at a molar ratio of 1:3.3 and magnetically stirred at 90°C for 6 hours to ensure complete reaction, yielding a eutectic solvent extractant. A eutectic solvent extractant with a flow rate of 100 kmol / h was introduced from the top of extraction column T1, while the oleophenol mixture feedstock with a flow rate of 250 kmol / h was introduced from the bottom of the extraction column (the molar ratio of extractant to intermediate cresol in the feedstock was 1:1). Countercurrent contact extraction was carried out in extraction column T1 at a temperature of 25°C and a pressure of 1 atm. The top of the column yielded raffinate D1 (removed phenol oil) at a flow rate of 99.49 kmol / h, with a neutral oil content of 98.7%. The bottom of the column yielded extract B1 at a flow rate of 250.51 kmol / h, with a m-cresol extraction rate of 99.8%. Extract B1 entered flash evaporator F1 and was flashed at 0.1 atm and 180 °C. The top of the flash evaporator yielded a neutral oil-rich fraction D2 at a flow rate of 49.05 kmol / h, containing a neutral oil content of 83.0%. The bottom of the flash evaporator yielded a neutral oil-removed extract B2, which entered flash evaporator F2 and was flashed at 0.1 atm and 225 °C. The top of the flash evaporator yielded a phenol-rich fraction D3 at a flow rate of 69.19 kmol / h. Gas chromatography analysis showed that the m-cresol content was 81.2% and the neutral oil content was 5.7%. The phenol-rich fraction D3 enters distillation column T2, which has 30 trays, with the feed tray being the 20th tray, and a reflux ratio of 4. After distillation, the lowest azeotrope D4, consisting of tetrahydronaphthalene, undecane, and m-cresol, is obtained at the top of the column with a flow rate of 9.23 kmol / h. The bottom fraction, m-cresol and triethylene glycol effluent B4, containing phenol and a small amount of hydrogen bond donors, is obtained at a flow rate of 59.96 kmol / h. B4 enters recovery distillation column T3, which has 40 trays, with the feed tray being the 20th tray, and a reflux ratio of 1. After distillation, the top fraction yields m-cresol product with a flow rate of 42.16 kmol / h and a purity of 99.7%, while the bottom fraction, triethylene glycol effluent (hydrogen bond donor B5), is obtained at a flow rate of 17.49 kmol / h and is recycled after being mixed with B3.

Claims

1. A method for separating an oil-phenol mixture by eutectic solvent extraction coupled with distillation, the method comprising the following steps: (1) The hydrogen bond acceptor and the hydrogen bond donor are mixed and stirred in a given molar ratio to obtain a eutectic solvent; (2) Add the eutectic solvent extractant prepared in step (1) to the top of the extraction tower T1, so that it comes into countercurrent contact with the oil-phenol mixture entering from the bottom of the tower, and extract at a given temperature to obtain extract B1 and raffinate D1, where D1 is dephenolized oil. (3) The extract B1 obtained in step (2) is fed into flash tank F1 for flash evaporation to obtain neutral oil-rich fraction D2 and neutral oil-free extract B2. The neutral oil-rich fraction D2 is returned to the raw material oil-phenol mixture for further extraction. (4) The extract B2 obtained in step (3) after neutralizing oil is flashed into flash tank F2 to obtain phenol-rich fraction D3 and regenerated extractant B3. (5) The phenol-rich fraction D3 from step (4) is fed into the azeotropic distillation column T2 for distillation separation. A small amount of neutral oil and phenol azeotrope D4 is obtained at the top of the distillation column. The azeotrope D4 is returned to the bottom of the extraction column T1 for further extraction. A mixture B4 of phenol and a small amount of hydrogen bond donor is obtained at the bottom of the azeotropic distillation column T2. (6) The mixture B4 of phenol and a small amount of hydrogen bond donor obtained in step (5) is fed into the recovery distillation column T3 for distillation separation. Phenol product D5 is obtained at the top of the column, and a small amount of hydrogen bond donor B5 is obtained at the bottom of the column. The small amount of hydrogen bond donor B5 is mixed with the regenerated extractant B3 in step (4) and returned to the extraction column T1 for reuse. in, The hydrogen bond acceptor mentioned in step (1) is selected from one or both of betaine and L-carnitine; The hydrogen bond donors mentioned in step (1) are selected from one or both of triethylene glycol and tetraethylene glycol.

2. The method according to claim 1, characterized in that, The molar ratio of hydrogen bond acceptor to hydrogen bond donor in step (1) is 1:3.3 ~ 1:

4.

3. The method according to claim 1, characterized in that, In step (2), the molar ratio of the extractant to the phenol in the feedstock in the extraction tower is 0.6 to 1.

4.

4. The method according to claim 1, characterized in that, The temperature at which the eutectic solvent extractant separates the oleophenol mixture in step (2) is 25°C to 45°C.

5. The method according to claim 1, characterized in that, The pressure in the flash tank F1 described in step (3) is 0.05 atm ~ 0.1 atm, and the temperature is 150℃ ~ 180℃.

6. The method according to claim 1, characterized in that, The pressure of the flash tank F2 in step (4) is 0.05 atm ~ 0.1 atm, and the temperature is 200℃ ~ 225℃.

7. The method according to claim 1, characterized in that, In step (5), the number of trays in distillation column T2 is 30 to 40, the number of feed trays is 20 to 30, and the mass reflux ratio is 1 to 4.

8. The method according to claim 1, characterized in that, In step (6), the number of trays in the distillation recovery tower T3 is 30 to 40, the number of feed trays is 20 to 30, and the mass reflux ratio is 1 to 4.

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