A method for stepwise extraction of phenolic and pyridine compounds in naphthalene oil by using a eutectic solvent

Abstract

The application provides a method for step-by-step extraction of phenolic and pyridine compounds in naphthalene oil by using a eutectic solvent, comprising the following steps: step 1, mixing naphthalene oil with an alkane and a eutectic solvent, and separating to obtain a eutectic extraction phase and a solvent raffinate phase; step 2, mixing the eutectic extraction phase with a first stripping agent, and filtering to obtain a first stripping phase and a recyclable DES; step 3, distilling the first stripping phase to obtain a heteroatom mixture; mixing the heteroatom mixture with a hydrogen acceptor type eutectic extraction agent and an alkane, and separating to obtain a eutectic phenolic compound extraction phase and a pyridine compound alkane raffinate phase; step 4, mixing the phenolic compound extraction phase with a second stripping agent, and filtering to obtain a second stripping solution of phenol and a hydrogen acceptor type extraction agent; and distilling to recover the phenol product in the second stripping agent solution. The eutectic solvent is tetraethylammonium chloride, tetrabutylammonium chloride, tetrabutylammonium bromide or tetrabutylphosphonium bromide, and the eutectic solvent is combined with glycolic acid, oxalic acid, citric acid or p-toluenesulfonic acid.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of separation of coal chemical fine chemicals, and particularly relates to a method for step-by-step extraction of phenolic compounds and pyridine compounds in naphthalene oil by using a eutectic solvent. BACKGROUND

[0002] Coal tar and liquefied oil are important coal-based liquid chemical products, and a series of mixed products of phenols and aromatic hydrocarbons can be obtained through vacuum rectification. Among them, industrial naphthalene oil is an important source of phenol and pyridine compounds. Because the phenolic hydroxyl group is usually acidic, and there is a B acid-L base interaction between the basic compound pyridine derivative and the benzene ring, and there is a wide range of π-π interaction between the benzene rings, so the benzene, phenol, pyridine and naphthalene derivatives are always enriched in the naphthalene oil fraction. Therefore, developing an efficient and simple operation method for separating phenol, pyridine derivatives and benzene, naphthalene mixture is a major difficulty in the value-added utilization of modern coal-based liquid fine chemicals.

[0003] There are some mature industrial processes for separating phenol and quinoline mixtures. When industrial naphthalene oil is processed, first, the naphthalene oil fraction is washed with strong acid such as sulfuric acid to obtain the sulfate salt of the basic quinoline substance, and then the quinoline sulfate is reconditioned with dilute alkali. Then, the naphthalene oil after acid washing is neutralized with strong base and phenolate is obtained by alkali washing, and finally the basic nitrogen-containing substance is reconditioned with dilute acid. This method is complicated to operate, and more importantly, it involves repeated use of strong acid and alkali, which is corrosive to equipment, has a complex process and high energy consumption, and also pollutes the surrounding water.

[0004]

[0005] PhOH + NaOH → PhONa + H2O

[0006] PhO - +H + →PhOH

[0007] Based on the above analysis, the method for separating phenol and pyridine compounds in industrial naphthalene oil in the prior art has harsh conditions, and the acid and alkali extraction solvents cannot be recycled. Therefore, it is urgent to develop a simple, efficient and easy-to-recycle method for separating phenol and pyridine compounds in industrial naphthalene oil. SUMMARY

[0008] The main purpose of the present application is to provide a method for step-by-step extraction of phenolic compounds and pyridine compounds in naphthalene oil by using a eutectic solvent, so as to overcome the defects of the prior art that the separation method needs to use strong acid and alkali, which is corrosive to equipment, pollutes the environment and has high energy consumption.

[0009] In order to achieve the above purpose, the present application provides a method for step-by-step extraction of phenolic compounds and pyridine compounds in naphthalene oil by using a eutectic solvent, comprising the following steps:

[0010] Step 1, mixing naphthalene oil, alkane and eutectic solvent, separating to obtain heteroatom eutectic phase and hydrocarbon raffinate phase;

[0011] Step 2, mixing the heteroatom eutectic phase with a first stripping agent, and separating to obtain a first stripping phase and a first stripping raffinate phase;

[0012] Step 3, separating the heteroatom mixture in the first stripping phase from the first stripping agent, mixing the heteroatom mixture, alkane and hydrogen bond acceptor extractant, and separating to obtain a phenolic eutectic phase and a pyridine raffinate phase;

[0013] Step 4, mixing the phenolic eutectic phase with a second stripping agent, and separating to obtain a phenolic compound;

[0014] In the method, the eutectic solvent is a mixture of at least one of tetraethylammonium chloride, tetrabutylammonium chloride, tetrabutylammonium bromide and tetrabutylphosphonium bromide and at least one of glycolic acid, oxalic acid, citric acid and p-toluenesulfonic acid; and the hydrogen bond acceptor extractant is at least one of tetraethylammonium chloride, tetrabutylammonium chloride, tetrabutylammonium bromide and tetrabutylphosphonium bromide.

[0015] The method for step-by-step extraction of phenolic and pyridine compounds in naphthalene oil by using eutectic solvent according to the application further comprises:

[0016] The hydrocarbon raffinate phase in step 1 is subjected to distillation to obtain alkane, benzene and naphthalene mixture respectively; and the alkane is recycled to step 1 for reuse.

[0017] In the method for step-by-step extraction of phenolic and pyridine compounds in naphthalene oil by using eutectic solvent according to the application, the first stripping agent is at least one of acetone, ethyl acetate, carbon disulfide and tetrachloromethane; and the first stripping raffinate phase is eutectic solvent, which is recycled to step 1 for reuse.

[0018] In the method for step-by-step extraction of phenolic and pyridine compounds in naphthalene oil by using eutectic solvent according to the application, the first stripping agent is at least one of acetone, ethyl acetate, carbon disulfide and tetrachloromethane; and the first stripping raffinate phase is eutectic solvent, which is recycled to step 1 for reuse.

[0019] In the method for step-by-step extraction of phenolic and pyridine compounds in naphthalene oil by using eutectic solvent according to the application, the second stripping agent is at least one of acetone, ethyl acetate, carbon disulfide and tetrachloromethane; and the mixture of the phenolic eutectic phase and the second stripping agent is subjected to phase separation to obtain a phenolic compound and a hydrogen bond acceptor extractant, and the hydrogen bond acceptor extractant obtained by phase separation is recycled to step 3 for reuse.

[0020] The method for step-by-step extraction of phenolic compounds and pyridine compounds in naphthalene oil by using a eutectic solvent, wherein the pyridine raffinate is separated by distillation to obtain pyridine compounds and alkanes, and the alkanes are recycled.

[0021] The method for step-by-step extraction of phenolic compounds and pyridine compounds in naphthalene oil by using a eutectic solvent, wherein the alkanes in step 1 and the alkanes in step 3 are the same or different and are independently selected from n-hexane and cyclohexane.

[0022] The method for step-by-step extraction of phenolic compounds and pyridine compounds in naphthalene oil by using a eutectic solvent, wherein in step 1, the mass ratio of the eutectic solvent to naphthalene oil is 0.2-2, the mixing temperature is 30-50°C, and the mixing time is 60-120 min.

[0023] The method for step-by-step extraction of phenolic compounds and pyridine compounds in naphthalene oil by using a eutectic solvent, wherein in step 3, the mixing temperature is 30-50°C; in step 2, the mass ratio of the first stripping agent to the heteroatom eutectic phase is 0.5-1, and the mixing time is 10-30 min; and in step 4, the mass ratio of the second stripping agent to the phenolic eutectic phase is 0.5-1, and the mixing time is 10-30 min.

[0024] The method for step-by-step extraction of phenolic compounds and pyridine compounds in naphthalene oil by using a eutectic solvent, wherein in the eutectic solvent, the molar ratio of tetraethylammonium chloride, tetrabutylammonium chloride, tetrabutylammonium bromide or tetrabutylphosphonium bromide to glycolic acid, oxalic acid, citric acid or p-toluenesulfonic acid is 2:1-1:2.

[0025] The present application has the following advantages:

[0026] The present application uses a eutectic solvent and a hydrogen bond acceptor extractant as an extractant, combines stripping and distillation, etc., to achieve high-selectivity separation of phenolic compounds and pyridine compounds in naphthalene oil, which is simple and efficient, has mild extraction conditions, and the extractant can be recycled after drying, the stripping agent and the alkane solvent can be recycled by atmospheric distillation, and the reagents used do not corrode the equipment. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 The present application has the following advantages: DETAILED DESCRIPTION

[0028] The technical solutions of the present application are described in detail below. The following embodiments are implemented on the premise of the technical solutions of the present application, and detailed implementation processes are given. However, the protection scope of the present application is not limited to the following embodiments. The structures or experimental methods not specified in the following embodiments are generally performed under conventional conditions.

[0029] The present application provides a method for step-by-step extraction of phenolic and pyridine compounds in naphthalene oil using a eutectic solvent, comprising the following steps:

[0030] Step 1: mixing naphthalene oil, alkane and eutectic solvent, and separating to obtain a heteroatom eutectic phase and a hydrocarbon raffinate phase;

[0031] Step 2: mixing the heteroatom eutectic phase with a first stripping agent, and separating to obtain a first stripping phase and a first stripping raffinate phase;

[0032] Step 3: separating the heteroatom mixture in the first stripping phase from the first stripping agent, mixing the heteroatom mixture, alkane and a hydrogen bond acceptor extractant, and separating to obtain a phenolic eutectic phase and a pyridine raffinate phase;

[0033] Step 4: mixing the phenolic eutectic phase with a second stripping agent, and separating to obtain phenolic compounds;

[0034] In the present application, the eutectic solvent is a mixture of at least one of tetraethylammonium chloride, tetrabutylammonium chloride, tetrabutylammonium bromide and tetrabutylphosphonium bromide and at least one of glycolic acid, oxalic acid, citric acid and p-toluenesulfonic acid; and the hydrogen bond acceptor extractant is at least one of tetraethylammonium chloride, tetrabutylammonium chloride, tetrabutylammonium bromide and tetrabutylphosphonium bromide.

[0035] In the present application, the eutectic solvent and the hydrogen bond acceptor extractant are used as extractants, combined with stripping and distillation, to achieve high-selective separation of phenolic compounds and pyridine compounds in naphthalene oil. The operation is simple and efficient, the extraction conditions are mild, the extractant can be recycled after drying, the stripping agent and the alkane solvent can be recycled by atmospheric distillation, and the reagents used do not corrode the equipment.

[0036] In the present application, naphthalene oil refers to the naphthalene oil fraction of coal tar at normal pressure of 210-230℃, which is rich in phenolic, pyridine compounds and naphthalene derivatives. The general composition ratio is: the mass ratio of phenolic to pyridine is 2 or more, and the mass of naphthalene derivatives is more than 50%. In an embodiment, the present application configures a model oil according to the mass ratio of phenol:pyridine:aromatic hydrocarbon=2:1:3. The composition of real naphthalene oil varies greatly, and the phenolic compounds are quantified after normalization by gas chromatography. The extraction and separation are completed according to the ratio of the present application. The pyridine compounds in the present application refer to pyridine, quinoline, etc., and the phenolic compounds refer to phenol, ethyl phenol, etc.

[0037] In an embodiment, the present application first mixes naphthalene oil with alkane to form a solution, and then extracts the solution with a eutectic solvent. The present application does not particularly limit the alkane, which can be a low-boiling alkane, such as n-hexane, cyclohexane, or the like. In another embodiment, the concentration of naphthalene oil in the solution formed by naphthalene oil and alkane is 180 g / kg to 360 g / kg. In yet another embodiment, the mass ratio of the amount of eutectic solvent added to the mass of naphthalene oil is 0.2 to 2. The extraction process can be performed with stirring. The temperature at which the above-mentioned solution is mixed with the eutectic solvent for extraction can be 30°C to 50°C, and the time for which the mixture is extracted can be 60 min to 120 min. After the extraction is completed, the mixture is allowed to stand and separate. The present application does not particularly limit the method of separation, which can be performed by pouring or using a dropper to draw off the liquid. A heteroatom eutectic phase and a hydrocarbon raffinate phase are obtained. The heteroatom eutectic phase mainly includes the eutectic solvent and the heteroatom compound, and the hydrocarbon raffinate phase mainly includes benzene, naphthalene compounds, and the alkane solvent.

[0038] The hydrocarbon extraction phase can be distilled to recover the alkane solvent and obtain a benzene-naphthalene mixture. The distillation method is not particularly limited by the present application and can be, for example, atmospheric distillation. The recovered alkane solvent can be recycled, and the benzene-naphthalene mixture can be output as a product and used as a raw material for other processes.

[0039] The heteroatom eutectic phase is mixed with a first back-extraction agent, and the mixture is separated to obtain a first back-extraction phase and a first back-extraction raffinate.

[0040] In an embodiment, the first back-extraction agent is selected from acetone, ethyl acetate, carbon disulfide, tetrachloromethane, and the like. In another embodiment, the mass ratio of the amount of first back-extraction agent added to the mass of heteroatom eutectic phase is 0.5 to 1. The heteroatom eutectic phase is mixed with the first back-extraction agent for back-extraction. The mixture can be stirred during the mixing process, the mixing temperature can be room temperature, i.e., 20-30°C, and the mixing time can be 10 min to 30 min. The mixture is then separated to obtain a first back-extraction phase and a first back-extraction raffinate.

[0041] The first back-extraction raffinate mainly includes the eutectic solvent, which can be dried and recycled. The first back-extraction phase mainly includes the first extraction agent and the heteroatom compound. The first back-extraction phase can be distilled, for example, by atmospheric distillation, to separate the heteroatom mixture and the first back-extraction agent in the first back-extraction phase, thereby obtaining the heteroatom compound and the first back-extraction agent with a yield of greater than 98% each. The first back-extraction agent obtained by distillation can be recycled.

[0042] The heteroatom mixture, the alkane, and a hydrogen bond acceptor extraction agent are mixed, and the mixture is separated to obtain a phenolic eutectic phase and a pyridine raffinate phase.

[0043] In an embodiment, the mixture of heteroatoms is mixed with an alkane solvent to form a solution, and then mixed with a hydrogen bond acceptor extractant to perform extraction. The alkane solvent is not particularly limited in the present application, and can be a low-boiling alkane, such as n-hexane, cyclohexane, etc. In another embodiment, the amount of the alkane solvent added is 1-5 times the mass of the mixture of heteroatoms. In yet another embodiment, the amount of the hydrogen bond acceptor extractant added is 0.5-1 times the molar amount of the phenols in the naphthalene oil. Mixing and extraction can be performed with stirring, and the temperature during mixing and extraction can be 30-50°C, such as 40°C or 50°C. After extraction is complete, the mixture can be separated by decanting or pipetting to obtain a phenolic eutectic phase and a pyridine raffinate phase. The phenolic eutectic phase mainly includes the hydrogen bond acceptor extractant and the target phenol, and the pyridine raffinate phase mainly includes pyridine compounds and the alkane solvent.

[0044] The pyridine raffinate phase is distilled, such as by atmospheric distillation, to obtain pyridine compounds with a purity greater than 99%. The alkane solvent obtained by distillation can be recycled.

[0045] The phenolic eutectic phase is mixed with a second stripping agent, and separated to obtain a phenolic compound.

[0046] In an embodiment, the second stripping agent is the same as or different from the first stripping agent, and can be selected from acetone, ethyl acetate, carbon disulfide, tetrachloromethane, etc. In another embodiment, the amount of the second stripping agent added is 0.5-1 times the mass of the phenolic eutectic phase. The phenolic eutectic phase is mixed with the second stripping agent to perform stripping, and the mixing can be performed with stirring, and the mixing temperature can be room temperature, i.e., 20-30°C, and the mixing time can be 10-30 min. The mixture is then separated to obtain a second stripping phase containing a phenolic compound and a second stripping raffinate phase. The second stripping phase mainly includes the phenolic compound and the second stripping agent, and the second stripping raffinate phase mainly includes the hydrogen bond acceptor extractant.

[0047] The second stripping raffinate phase is dried to obtain the hydrogen bond acceptor extractant, which can be recycled. The second stripping phase is distilled, such as by atmospheric distillation, to obtain a phenolic compound with a purity greater than 90%, and the second stripping agent obtained by distillation can be recycled.

[0048] Thus, the present application provides a method for extracting and separating phenols and pyridine compounds from a typical mixture of coal-based liquid naphthalene oil, which takes a coal tar naphthalene oil fraction (210-230 DEG C) rich in phenols, pyridine and naphthalene derivatives as the separation object, and the extraction and separation process comprises: dissolving the naphthalene oil in an alkane solvent, using an acidic eutectic solvent as the extractant, completing liquid-liquid extraction by forming a two-phase with the alkane solvent, and the acidic eutectic solvent capturing the heteroatomic compounds in the naphthalene oil fraction; then obtaining the heteroatomic compounds (including phenols and basic nitrogen heterocyclic compounds) by means of back extraction; then realizing high selective separation of phenols and pyridine compounds by using the characteristics that the hydrogen bond acceptor extractant is easy to associate with phenols to form a low common phase; and finally obtaining the phenols and pyridine compounds by means of back extraction and distillation. The method of the present application is simple and efficient, the extraction conditions are mild, the extractant can be recycled after drying, and the back extraction agent and the alkane solvent can be recycled by atmospheric distillation.

[0049] The acidic eutectic solvent extractant in the present application realizes separation from the heteroatomic compounds by hydrogen bonding and acid-base synergistic effect, and the selective separation of phenols and pyridine compounds relies on the structural difference that the pyridine group does not have hydrogen bond donor sites. The extraction principle is analyzed by combining the charge shielding surface density model of COSMO-RS software: (1) the interaction energy between the extractant and the heteroatomic compounds is greater than the interaction energy of the heteroatomic compounds in the alkane solvent with aromatic hydrocarbons, so that the extractant breaks the original association structure; (2) the hydrogen bond acceptor extractant has a significant hydrogen bond interaction with phenols, and the structural difference that the pyridine group lacks a hydrogen bond donor site is used to realize high selective extraction of phenols. Preliminary screening is completed by combining interaction energy calculation, the preferred acidic eutectic solvent of the present application is selected from at least one of tetraethylammonium chloride, tetrabutylammonium chloride, tetrabutylammonium bromide, tetrabutylphosphonium bromide and at least one of glycolic acid, oxalic acid, citric acid, p-toluenesulfonic acid; and the preferred hydrogen bond acceptor extractant is selected from at least one of tetraethylammonium chloride, tetrabutylammonium chloride, tetrabutylammonium bromide and tetrabutylphosphonium bromide.

[0050] Compared with the traditional acid-base extraction and separation method, the method for extracting and separating phenols and pyridine compounds provided by the present application has the following advantages: (1) simple process operation, the extractant and the solvent are added to the reaction at one time, and liquid-liquid extraction can be completed by simple liquid separation; (2) mild separation conditions, the separation process temperature is between 30 DEG C and 50 DEG C, and the process energy consumption is low; (3) organic solvent is used for back extraction in the separation, and DES (eutectic solvent) is used for extraction, both of which can be reused without water pollution; (4) the overall process operation has high degree of continuity and strong industrial amplification potential.

[0051] The application also provides a system diagram for separating phenols and pyridine compounds from naphthalene oil. The naphthalene oil mixture F1, the alkane solvent Sol and the eutectic solvent E1 are mixed and extracted in a decontamination kettle DH to obtain a heteroatom eutectic phase (DES extraction phase) and a hydrocarbon raffinate phase. The hydrocarbon extraction phase enters a solvent column ST, and the obtained solvent is recycled by distillation. The benzene naphthalene mixture enters a P3 storage tank. The DES extraction phase and a back extraction agent are mixed and extracted in a back extraction column BE to obtain a heteroatom mixture F2, and the back extraction agent is recycled. The heteroatom mixture F2 and a hydrogen bond acceptor extraction agent E2 and an alkane solvent Sol are extracted in a phenol extraction kettle PH to obtain a phenolic eutectic phase (DES extraction phase) and a pyridine raffinate phase. The phenolic eutectic phase (DES extraction phase) and a back extraction agent are mixed and extracted in a back extraction column BE to obtain a product mixed phenol P1, and the back extraction agent is recycled. The pyridine raffinate phase enters a solvent column ST, and the obtained solvent is recycled by distillation. The pyridine compound enters a P2 storage tank.

[0052] The technical scheme of the application is further described below through specific examples, but the protection scope of the application is not limited to the following examples. Unless otherwise specified, the raw materials, reagents and methods used in the examples are conventional raw materials, reagents and methods in the art. In the following part of the examples, ethyl phenol, quinoline and methyl naphthalene are used to prepare a model naphthalene oil with a mass ratio of 2:1:3 as raw materials for determination.

[0053] Example 1

[0054] A model naphthalene oil is used as a raw material, which is dissolved in cyclohexane to prepare a 180 g / kg solution. 100 g of the solution is placed in a triangular flask with magnetic stirring. Tetraethylammonium chloride and oxalic acid eutectic extraction agent are prepared according to a molar ratio of 1:2. 18 g of the eutectic extraction agent (mass ratio of 1 to naphthalene oil) is added. After stirring at 30℃ for 60 min, the DES phase is obtained by liquid separation. 9 g of ethyl acetate is added as a back extraction agent. After back extraction for 30 min, an anti-extraction solution containing ethyl phenol and quinoline is obtained. After distillation, 8.82 g of a mixture of ethyl phenol and quinoline is obtained, with a yield of 98.1%. Then 4.06 g of tetraethylammonium chloride (molar ratio of 0.5 to phenol) and 45 g of cyclohexane are added. After stirring at 50℃ for 60 min, the DES phase is obtained by liquid separation. 9 g of ethyl acetate is added to the DES phase and stirred at room temperature for 10 min. The back extraction phase is distilled to obtain 6.19 g of ethyl phenol with a purity of 95%. The alkane solvent phase obtains 2.63 g of quinoline with a purity of 99%.

[0055] Example 2

[0056] A model naphthalene oil was used as raw material, which was dissolved in cyclohexane to prepare a solution of 180 g / kg. 100 g of the solution was placed in a flask with magnetic stirring, and a eutectic extractant of tetraethylammonium chloride and glycolic acid was prepared according to a molar ratio of 1:2. 36 g of the eutectic extractant (mass ratio of 2 to naphthalene oil) was added, and after stirring at 50 °C for 120 min, the DES phase was obtained by liquid separation. 18 g of acetone was added as a stripping agent, and after stripping for 30 min, a stripping solution containing ethyl phenol and quinoline was obtained. After distillation, 8.28 g of a mixture of ethyl phenol and quinoline was obtained, with a yield of 92%. Then 4.06 g of tetraethylammonium chloride (molar ratio of 0.5 to phenol) and 45 g of cyclohexane were added, and after stirring at 50 °C for 60 min, the DES phase was obtained by liquid separation. 9 g of ethyl acetate was added to the DES phase at room temperature and stirred for 10 min, and after distillation of the stripping phase, 5.75 g of ethyl phenol was obtained, with a purity of 96%. The alkane solvent phase obtained 2.53 g of quinoline, with a purity of 99%.

[0057] Example 3

[0058] A model naphthalene oil was used as raw material, which was dissolved in cyclohexane to prepare a solution of 180 g / kg. 100 g of the solution was placed in a flask with magnetic stirring, and a eutectic extractant of tetraethylammonium chloride and glycolic acid was prepared according to a molar ratio of 1:2. 36 g of the eutectic extractant (mass ratio of 2 to naphthalene oil) was added, and after stirring at 50 °C for 120 min, the DES phase was obtained by liquid separation. 18 g of acetone was added as a stripping agent, and after stripping for 30 min, a stripping solution containing ethyl phenol and quinoline was obtained. After distillation, 8.28 g of a mixture of ethyl phenol and quinoline was obtained, with a yield of 92%. Then 4.06 g of tetraethylammonium chloride (molar ratio of 0.5 to phenol) and 45 g of cyclohexane were added, and after stirring at 50 °C for 60 min, the DES phase was obtained by liquid separation. 9 g of ethyl acetate was added to the DES phase at room temperature and stirred for 10 min, and after distillation of the stripping phase, 5.75 g of ethyl phenol was obtained, with a purity of 96%. The alkane solvent phase obtained 2.53 g of quinoline, with a purity of 99%.

[0059] Example 4

[0060] A model naphthalene oil was used as raw material, which was dissolved in cyclohexane to prepare a solution of 360 g / kg. 100 g of the solution was placed in a flask with magnetic stirring, and tetrabutylammonium bromide and p-toluenesulfonic acid eutectic extractant was prepared according to the molar ratio of 1:2. 7.2 g of the eutectic extractant (mass ratio of naphthalene oil 0.2) was added, stirred at 50°C for 60 min, and then the DES phase was obtained by liquid separation. Then 36 g of acetone was added as a stripping agent, and after stripping for 30 min, a stripping solution containing ethyl phenol and quinoline was obtained. After distillation, 17.71 g of a mixture of ethyl phenol and quinoline was obtained, with a yield of 98.41%. Then 16.24 g of tetraethylammonium chloride (molar ratio of phenol 1) and 18 g of cyclohexane were added, stirred at 50°C for 60 min, and then the DES phase was obtained by liquid separation. 18 g of carbon disulfide was added to the DES phase and stirred at room temperature for 10 min. The distillation stripping phase obtained 13.12 g of ethyl phenol with a purity of 90%, and the alkane solvent phase obtained 4.59 g of quinoline with a purity of 99%.

[0061] Example 5

[0062] A model naphthalene oil was used as raw material, which was dissolved in cyclohexane to prepare a solution of 360 g / kg. 100 g of the solution was placed in a flask with magnetic stirring, and tetrabutylammonium bromide and p-toluenesulfonic acid eutectic extractant was prepared according to the molar ratio of 1:2. 7.2 g of the eutectic extractant (mass ratio of naphthalene oil 0.2) was added, stirred at 50°C for 60 min, and then the DES phase was obtained by liquid separation. Then 36 g of acetone was added as a stripping agent, and after stripping for 30 min, a stripping solution containing ethyl phenol and quinoline was obtained. After distillation, 17.71 g of a mixture of ethyl phenol and quinoline was obtained, with a yield of 98.41%. Then 16.24 g of tetraethylammonium chloride (molar ratio of phenol 1) and 18 g of cyclohexane were added, stirred at 50°C for 60 min, and then the DES phase was obtained by liquid separation. 18 g of carbon disulfide was added to the DES phase and stirred at room temperature for 10 min. The distillation stripping phase obtained 13.12 g of ethyl phenol with a purity of 90%, and the alkane solvent phase obtained 4.59 g of quinoline with a purity of 99%.

[0063] Example 6

[0064] The model naphthalene oil was used as raw material, which was dissolved in cyclohexane to prepare a solution of 360 g / kg. 100 g of the solution was placed in a flask with magnetic stirring, and the eutectic extractant of tetraethylammonium chloride and oxalic acid was prepared according to the molar ratio of 1:2. 36 g of the eutectic extractant (mass ratio of 1 to naphthalene oil) was added, stirred at 50°C for 60 min, and then the DES phase was obtained by liquid separation. 18 g of ethyl acetate was added as a stripping agent, and after stripping for 30 min, a stripping solution containing ethyl phenol and quinoline was obtained. After distillation, 17.48 g of a mixture of ethyl phenol and quinoline was obtained, with a yield of 97.11%. Then 27.36 g of tetrabutylammonium chloride (molar ratio of 1 to ethyl phenol) and 90 g of cyclohexane were added, stirred at 50°C for 60 min, and then the DES phase was obtained by liquid separation. 18 g of ethyl acetate was added in the DES phase and stirred at room temperature for 10 min. The stripping phase was distilled to obtain 12.40 g of ethyl phenol with a purity of 94%, and the alkane solvent phase obtained 5.08 g of quinoline with a purity of 99%.

[0065] Example 7

[0066] The model naphthalene oil was used as raw material, which was dissolved in cyclohexane to prepare a solution of 360 g / kg. 100 g of the solution was placed in a flask with magnetic stirring, and the eutectic extractant of tetraethylammonium chloride and oxalic acid was prepared according to the molar ratio of 1:2. 36 g of the eutectic extractant (mass ratio of 1 to naphthalene oil) was added, stirred at 50°C for 60 min, and then the DES phase was obtained by liquid separation. 18 g of ethyl acetate was added as a stripping agent, and after stripping for 30 min, a stripping solution containing ethyl phenol and quinoline was obtained. After distillation, 17.48 g of a mixture of ethyl phenol and quinoline was obtained, with a yield of 97.11%. Then 27.36 g of tetrabutylammonium chloride (molar ratio of 1 to ethyl phenol) and 90 g of cyclohexane were added, stirred at 50°C for 60 min, and then the DES phase was obtained by liquid separation. 18 g of ethyl acetate was added in the DES phase and stirred at room temperature for 10 min. The stripping phase was distilled to obtain 12.40 g of ethyl phenol with a purity of 94%, and the alkane solvent phase obtained 5.08 g of quinoline with a purity of 99%.

[0067] Example 8

[0068] The model naphthalene oil was used as raw material, which was dissolved in hexane to prepare a solution of 360 g / kg. 100 g of the solution was placed in a flask with magnetic stirring, and the eutectic extractant of tetraethylammonium chloride and oxalic acid was prepared according to the molar ratio of 2:1. 36 g of the eutectic extractant (mass ratio of 1 to naphthalene oil) was added, stirred at 50 °C for 60 min, and then the DES phase was obtained by liquid separation. 18 g of carbon tetrachloride was added as a stripping agent, and after stripping for 30 min, a stripping solution containing ethyl phenol and quinoline was obtained. After distillation, 17.72 g of a mixture of ethyl phenol and quinoline was obtained, with a yield of 98.45%. Then 31.68 g of tetrabutylphosphonium bromide (molar ratio of 1 to ethyl phenol) and 90 g of cyclohexane were added, stirred at 50 °C for 60 min, and then the DES phase was obtained by liquid separation. 36 g of carbon tetrachloride was added to the DES phase at room temperature and stirred for 10 min, and then the stripping phase was distilled to obtain 13.27 g of ethyl phenol with a purity of 89%; the alkane solvent phase obtained 4.45 g of quinoline with a purity of 99%.

[0069] Example 9

[0070] The model naphthalene oil was used as raw material, which was dissolved in cyclohexane to prepare a solution of 360 g / kg. 100 g of the solution was placed in a flask with magnetic stirring, and the eutectic extractant of tetraethylammonium chloride and oxalic acid was prepared according to the molar ratio of 2:1. 36 g of the eutectic extractant (mass ratio of 1 to naphthalene oil) was added, stirred at 50 °C for 60 min, and then the DES phase was obtained by liquid separation. 18 g of carbon tetrachloride was added as a stripping agent, and after stripping for 30 min, a stripping solution containing ethyl phenol and quinoline was obtained. After distillation, 17.72 g of a mixture of ethyl phenol and quinoline was obtained, with a yield of 98.45%. Then 31.68 g of tetrabutylphosphonium bromide (molar ratio of 1 to ethyl phenol) and 90 g of cyclohexane were added, stirred at 50 °C for 60 min, and then the DES phase was obtained by liquid separation. 36 g of carbon tetrachloride was added to the DES phase at room temperature and stirred for 10 min, and then the stripping phase was distilled to obtain 13.27 g of ethyl phenol with a purity of 89%; the alkane solvent phase obtained 4.45 g of quinoline with a purity of 99%.

[0071] Example 10

[0072] The model mixture was dissolved in cyclohexane to prepare a 360 g / kg solution. 100 g of the solution was placed in a flask with magnetic stirring, 36 g of DES extractant (mass ratio of naphthalene oil 1) was added, and stirred at 50°C for 60 min, and then the DES phase was separated. 18 g of ethyl acetate was added as a stripping agent, and after stripping for 30 min, the stripping solution containing alkyl phenols and quinolines was obtained, and after distillation, 18.7 g of a mixture of ethyl phenol and quinoline was obtained, with a yield of 96.3%. Then 16.24 g of tetraethylammonium chloride (molar ratio of ethyl phenol 1) and 90 g of cyclohexane were added, and after stirring at 50°C for 60 min, the DES phase was separated, and 36 g of carbon disulfide was added to the DES phase at room temperature and stirred for 10 min, and then the stripping phase was distilled to obtain 12.77 g of ethyl phenol with a purity of 95%; and the alkane solvent phase was obtained to obtain 5.93 g of quinoline with a purity of 97%.

[0073] Example 11

[0074] The industrial naphthalene oil sample (coal tar fraction at 210-230°C) was dissolved in cyclohexane to prepare a 180 g / kg solution. 100 g of the solution was placed in a flask with magnetic stirring, and the molar ratio of tetraethylammonium chloride and oxalic acid eutectic extractant was 1:2, 18 g of eutectic extractant (mass ratio of naphthalene oil 1) was added, and stirred at 30°C for 60 min, and then the DES phase was separated. 9 g of ethyl acetate was added as a stripping agent, and after stripping for 30 min, the stripping solution containing phenol and pyridine compounds was obtained, and after distillation, 8.21 g of a mixture of heteroatoms was obtained, with a yield of 104% (the naphthalene oil was quantified by GC-MS, and the total content of phenol and pyridine compounds in the naphthalene oil was determined by area normalization method to be 43.86 wt.%). Then 4.06 g of tetraethylammonium chloride (molar ratio of phenol 0.5) and 45 g of cyclohexane were added, and after stirring at 50°C for 60 min, the DES phase was separated, 9 g of ethyl acetate was added to the DES phase at room temperature and stirred for 10 min, and then the stripping phase was distilled to obtain 6.19 g of mixed phenol with a purity of 90%; and the alkane solvent phase was obtained to obtain 1.52 g of pyridine derivatives with a purity of 99%.

[0075] Of course, the present application can have other various embodiments, and those skilled in the art can make various corresponding changes and modifications according to the present application without departing from the spirit and essence of the present application, but these corresponding changes and modifications should all belong to the protection scope of the claims of the present application.

Claims

1. A method for fractional extraction of phenolic and pyridinic compounds from naphthalene oil using a deep eutectic solvent, characterized in that, The method comprises the following steps: Step 1, mixing naphthalene oil, alkane and eutectic solvent, separating to obtain heteroatom eutectic phase and hydrocarbon raffinate phase; Step 2, mixing the heteroatom eutectic phase with first stripping agent, separating to obtain first stripping phase and first stripping raffinate phase; Step 3, separating the heteroatom mixture in the first stripping phase from the first stripping agent, mixing the heteroatom mixture, alkane and hydrogen bond acceptor extractant, and separating to obtain phenolic eutectic phase and pyridine raffinate phase; Step 4, mixing the phenolic eutectic phase with second stripping agent, and separating to obtain phenolic compound; The eutectic solvent is a mixture of at least one of tetraethylammonium chloride, tetrabutylammonium chloride, tetrabutylammonium bromide and tetrabutylphosphonium bromide and at least one of glycolic acid, oxalic acid, citric acid and p-toluenesulfonic acid; and the hydrogen bond acceptor extractant is at least one of tetraethylammonium chloride, tetrabutylammonium chloride, tetrabutylammonium bromide and tetrabutylphosphonium bromide.

2. The method for fractional extraction of phenolic and pyridine compounds from naphthalene oil using deep eutectic solvent according to claim 1, characterized in that, Further comprising: The hydrocarbon raffinate phase in step 1 is subjected to distillation to obtain alkane, benzene and naphthalene mixture respectively; and the alkane is recycled to step 1 for reuse.

3. The method for fractional extraction of phenolic and pyridinic compounds from naphthalene oil using deep eutectic solvent as claimed in claim 1, wherein, The first stripping agent is selected from at least one of acetone, ethyl acetate, carbon disulfide and tetrachloromethane; and the first stripping raffinate phase is eutectic solvent, which is recycled to step 1 for reuse.

4. The method for fractional extraction of phenolic and pyridinic compounds from naphthalene oil using deep eutectic solvent as claimed in claim 1, wherein, The heteroatom mixture in the first stripping phase is separated from the first stripping agent by distillation, and the separated first stripping agent is recycled to step 2 for reuse.

5. The method for fractional extraction of phenolic and pyridinic compounds from naphthalene oil using deep eutectic solvent as claimed in claim 1, wherein, The second stripping agent is selected from at least one of acetone, ethyl acetate, carbon disulfide and tetrachloromethane; and the mixture of the phenolic eutectic phase and the second stripping agent is separated to obtain phenolic compound and hydrogen bond acceptor extractant, and the separated hydrogen bond acceptor extractant is recycled to step 3 for reuse.

6. The method for fractional extraction of phenolic and pyridinic compounds from naphthalene oil using deep eutectic solvent as claimed in claim 1, wherein, The pyridine raffinate phase is subjected to distillation to obtain pyridine compound and alkane, and the alkane obtained by distillation of the pyridine raffinate phase is recycled to step 3 for reuse.

7. The method for fractional extraction of phenolic and pyridinic compounds from naphthalene oil using deep eutectic solvent as claimed in claim 1, wherein, The alkane in step 1 and the alkane in step 3 are the same or different, and are independently selected from n-hexane and cyclohexane.

8. The method for fractional extraction of phenolic and pyridinic compounds from naphthalene oil using deep eutectic solvent as claimed in claim 1, wherein, In step 1, the mass ratio of eutectic solvent to naphthalene oil is 0.2-2, the mixing temperature is 30-50°C, and the mixing time is 60-120 min.

9. The method for fractional extraction of phenolic and pyridinic compounds from naphthalene oil using deep eutectic solvent as claimed in claim 1, wherein, In step 3, the mixing temperature is 30-50°C; in step 2, the mass ratio of first stripping agent to heteroatom eutectic phase is 0.5-1, and the mixing time is 10-30 min; in step 4, the mass ratio of second stripping agent to phenolic eutectic phase is 0.5-1, and the mixing time is 10-30 min.

10. The method for fractional extraction of phenolic and pyridinic compounds from naphthalene oil using deep eutectic solvent as claimed in claim 1, wherein, In the eutectic solvent, the ratio of the amount of substance of tetraethylammonium chloride, tetrabutylammonium chloride, tetrabutylammonium bromide or tetrabutylphosphonium bromide to the amount of substance of glycolic acid, oxalic acid, citric acid or p-toluenesulfonic acid is 2:1-1:2.

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