Impurity removal method for mixed phenol extracted from coal tar

Abstract

According to the impurity removal method for the mixed phenol extracted from the coal tar, a series of impurity removal treatment and refining purification treatment are conducted on the mixed phenol raw material, various high-purity phenol products are finally obtained, the method is low in raw material requirement, the impurity removal process is environmentally friendly, the impurity removal effect is good, and the method is suitable for industrial production. The method is especially suitable for impurity removal of crude phenol extracted from phenol-containing coal tar, phenol-containing phenol oil and phenol-containing coal direct liquefaction oil by adopting a solvent extraction method.

Description

Technical Field

[0001] The invention belongs to the technical field of separation of coal chemical products, and in particular, the invention relates to a method for removing impurities from mixed phenols extracted from coal tar. Background Art

[0002] Since most of the large-scale coking enterprises in China have their own tar deep processing projects, and with the development of downstream industries of various phenol products, the market demand for phenol raw materials has continued to expand. Large coking plants have arranged crude phenol refining projects on the basis of their own tar deep processing, resulting in coking phenol raw materials being difficult to obtain. The content of low-grade phenols in high-temperature coal tar is relatively low, so the overall scale of domestic high-temperature phenol processing is relatively small. In addition, due to high-temperature treatment, the crude phenol contains relatively few sulfur and nitrogen impurities, so the overall processing difficulty is relatively low.

[0003] Gasification crude phenol, pyrolysis crude phenol, coal liquefaction oil extraction crude phenol and gasification wastewater also contain a certain amount of crude phenol. Compared with coking crude phenol, these crude phenol raw materials have a larger output and are easier to obtain, but there are more impurities in these crude phenol raw materials, especially crude phenol extracted from phenol-containing coal tar, phenol-containing phenol oil, and coal direct liquefaction oil (including crude phenol extracted by alkaline water and solvent extraction). Due to entrainment, the crude phenol contains high contents of pyridine alkali, neutral oil, naphthalene oil, and sulfide. In addition, some impurities have a boiling point close to that of phenol products, which can easily enter the product and cause the product to change color and taste, increase the difficulty of operating the distillation tower, and cause a low phenol extraction rate. Although this kind of crude phenol raw material is difficult to process, due to its large output, the overall construction scale of the tar crude phenol refining project is large, and it is necessary to conduct in-depth research.

[0004] The main problem in the processing of pyrolysis and gasification phenol is the high impurity content of the raw materials. These impurities are not easy to remove by distillation separation, and their sources are complex and diverse. Since the properties of crude phenol raw materials produced by different types of coal and different processes are very different, the types and contents of impurities are also very different, which increases the difficulty of processing crude phenol. Summary of the invention

[0005] The present invention aims to solve one of the technical problems in the related art at least to a certain extent. To this end, an embodiment of the present invention provides a method for removing impurities from mixed phenol extracted from coal tar.

[0006] The embodiment of the present invention provides a method for removing impurities from mixed phenols extracted from coal tar, comprising the following steps:

[0007] S1: adding inorganic acid to the mixed phenol raw material, heating and stirring, and then continuing to heat up, while simultaneously dropping sulfuric acid during the heating process, removing water and some low-boiling substances by heat preservation, and then rectifying and dehydrating, removing residues, and obtaining dehydrated and deslagging crude phenol;

[0008] S2: adding an azeotropic agent, water and a reducing agent to the dehydrated and de-slaged crude phenol, heating and stirring, and then distilling the mixture, wherein the distillate is an azeotropic agent solution containing neutral oil, and the kettle liquid is subsequently processed;

[0009] S3: heating the kettle liquid obtained in step S2, adding alkaline substances and phase transfer catalysts, stirring for reaction, centrifuging to remove the lower alkaline water layer, heating the upper mixed phenol layer, and dripping sulfuric acid to react to obtain a mixed phenol liquid after impurities are removed; then, rectifying the mixed phenol liquid after impurities are removed to obtain various phenol fractions;

[0010] S4: recovering the entrainer in the entrainer solution containing neutral oil obtained in step S2;

[0011] S5: Mix the still residue obtained by the distillation of step S1 and the residue obtained by the distillation of step S3 and perform distillation treatment to obtain a catechol fraction with a distillation range of 242-250° C., a 5-indanol fraction with a distillation range of 253-258° C., and a resorcinol / hydroquinone fraction with a distillation range of 275-290° C.; then, post-treat the catechol fraction, the 5-indanol fraction, and the resorcinol / hydroquinone fraction, respectively, to obtain a fine catechol product, a fine 5-indanol product, a fine resorcinol product, and a fine hydroquinone product, respectively.

[0012] In some embodiments, the impurity removal method also includes subjecting the trimethylol fraction among the various phenol fractions obtained in step S3 to distillation, alkylation reaction, and crystallization to obtain at least one of 3,4-dimethylphenol, 3-ethyl-5-methylphenol, 2,3,5-trimethylol, and m / p-isopropylphenol.

[0013] In some embodiments, the step S3 further includes performing a color preserving treatment on the various phenol fractions by using a color preserving agent while distilling the mixed phenol liquid after impurities removal to collect various phenol fractions;

[0014] Preferably, the color preservative includes at least one of oxalic acid, hypophosphorous acid, hydrazine hydrate and ethylenediamine.

[0015] In some embodiments, in step S1, the inorganic acid includes at least one of sulfuric acid, hydrochloric acid, and phosphoric acid, the mass fraction of the inorganic acid is 60-98%, and the amount of the inorganic acid added is 0.8-2 times the mass of the pyridine base in the mixed phenol raw material;

[0016] And / or, the amount of sulfuric acid added is 0.05 to 2 times the mass of the pyridine base in the mixed phenol raw material.

[0017] In some embodiments, in step S1, the heating and stirring temperature is 60 to 90° C., and the stirring time is 0.5 to 1 h;

[0018] And / or, the heating temperature is 120-160° C., and the heating time is 1-2 hours;

[0019] And / or, the insulation time is 1 to 2 hours.

[0020] In some embodiments, in step S2, the azeotropic agent is an alcohol amine substance or a diol substance;

[0021] Preferably, the alcoholamine substance includes at least one of ethanolamine, diethanolamine, triethanolamine, and methyldiethanolamine, and the diol substance includes at least one of ethylene glycol, diethylene glycol, propylene glycol, and butanediol;

[0022] and / or, the reducing agent comprises at least one of methylhydroxylamine, hydrazine hydrate, hydroquinone, hypophosphorous acid, phosphorous acid, oxalic acid, zinc powder, sodium borohydride, potassium borohydride, lithium aluminum hydride, and butylated hydroxyanisole;

[0023] And / or, the temperature of the heating and stirring is 50-80° C., and the stirring time is 0.5-2 h.

[0024] In some embodiments, in step S2, the amount of the azeotropic agent added is 0.5 to 10 times the mass of the neutral oil in the dehydrated and deslagging crude phenol;

[0025] And / or, the amount of water added is 0 to 10 times the mass of the neutral oil in the dehydrated and de-slaged crude phenol;

[0026] And / or, the amount of the reducing agent added is 0.01 to 0.5% of the mass of the dehydrated and de-slaged crude phenol.

[0027] In some embodiments, in step S3, the alkaline substance includes at least one of sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, sodium hydroxide, and potassium hydroxide, and the amount of the alkaline substance added is 0.5 to 3 times the mass of the organic acid in the dehydrated and deslagging crude phenol obtained in step S1;

[0028] And / or, the phase transfer catalyst is polyethylene glycol or crown ether, and the added amount of the phase transfer catalyst is 0.01-0.5% of the mass of the dehydrated and deslagging crude phenol obtained in step S1.

[0029] In some embodiments, in step S3, the stirring reaction temperature is 60-90° C., and the reaction time is 1-2 h;

[0030] And / or, the heating temperature is 120-160° C. and the heating time is 1-2 hours.

[0031] In some embodiments, the specific steps of step S4 are as follows:

[0032] When the entrainer is an alcoholamine substance, the entrainer solution containing the neutral oil obtained in step S2 is heated to 30-40°C, CO2 is introduced, and then the temperature is raised to 40-50°C for stirring and reaction. After the alcoholamine is fully salified, sampling and analysis are performed until the alcoholamine content in the neutral oil remains unchanged, the CO2 is stopped, and the solution is allowed to stand for stratification. Excess CO2 is pressurized and applied by a pressure pump, and the alcoholamine carbonate is separated from the neutral oil; then the alcoholamine carbonate is heated to remove CO2, the obtained alcoholamine is applied, and the recovered CO2 gas is stored after being pressurized; hydrochloric acid is added to the neutral oil to neutralize the pH to 4-6. After stratification, the water layer is an aqueous solution of alcoholamine hydrochloride, and the oil layer is a neutral oil layer;

[0033] When the entrainer is a diol substance, liquid alkali is added to the entrainer solution containing neutral oil obtained in step S2 to neutralize the pH to 8-9, and the solution is separated after cooling, wherein the lower layer is a sodium phenolate solution containing diols, and the upper organic layer is a mixture of methylnaphthalene and naphthalene; the sodium phenolate solution containing diols is applied to step S2 as an entrainer.

[0034] The advantages and beneficial effects of the present invention are:

[0035] (1) The present invention takes into account that some crude phenol raw materials have low effective phenol content and many impurities with high boiling points. The high boiling point impurities have complex components, including some impurities that are easily condensed and polymerized under alkaline conditions. However, practice has shown that under alkaline conditions, the viscosity of the material is large and the material mixing effect is poor. In addition, alkali is easy to form agglomerated sodium phenol salts with phenol, which are then wrapped on the surface of the heater and deposited in large quantities at the bottom of the tower kettle, resulting in poor heat transfer effect and difficulty in slag removal, which is not conducive to the refining of crude phenol. Therefore, the present invention preferably chooses to first add acid to treat the nitrogen-containing organic matter that is easy to change color, and then add alkali or other agents to further remove impurities according to the impurity situation of the mixed phenol with low viscosity after dehydration and slag removal.

[0036] (2) In steps S1 and S3 of the present invention, sulfuric acid having acidity, oxidizing properties, reactivity and catalysis is preferably used, but volatile hydrochloric acid, strong oxidizing properties, volatile and unsafe nitric acid and the like are not selected. This is mainly because the acidity of dilute sulfuric acid (which can form salts with basic nitrogen-containing compounds such as pyridine and aniline) and the oxidizing properties of concentrated sulfuric acid (which can oxidize some sulfur-containing compounds, anilines and the like when heated) can be utilized, and concentrated sulfuric acid can react with phenol and anilines to generate phenolsulfonic acid, anilinesulfonic acid and the like when heated as a reaction reagent, thereby reducing the corrosion of the distillation tower by sulfuric acid vapor, and phenolsulfonic acid can also react with nitrogen-containing organic compounds to remove pyridine alkali; and concentrated sulfuric acid can be used as a catalyst to catalyze the polymerization of olefinic substances such as indene and methylindene into resins, thereby removing easily polymerized unsaturated compounds such as indene that are easily blackened.

[0037] (3) In order to ensure the quality of the phenolic products obtained by azeotropic distillation, the crude phenol is preliminarily treated with inorganic acid and sulfuric acid to remove impurities such as pyridine bases, anilines, sulfides, organic acids, etc., and a suitable entrainer is selected for targeted treatment according to the type and content of the neutral oil in the phenolic product. The impurity removal effect is good and the operating cost is low. The quality of the obtained phenolic products is close to or exceeds the level of petrochemical-grade products.

[0038] (4) In order to improve the reaction efficiency of alkali with organic acid, thiophenol and thiol in mixed phenol, the present invention adds a polyethylene glycol or crown ether phase transfer catalyst with good stability to improve the reaction selectivity, and removes organic acid, thiophenol and the like as efficiently as possible to reduce the loss caused by the reaction of strong alkali with phenol products to form sodium phenol. DETAILED DESCRIPTION

[0039] Embodiments of the present invention are described in detail below. The embodiments are exemplary and intended to be used to explain the present invention, but should not be construed as limiting the present invention.

[0040] Where values ​​are described herein as a range, it should be understood that such disclosure includes disclosure of all possible sub-ranges within that range, as well as specific values ​​falling within that range, regardless of whether a specific value or a specific sub-range is explicitly stated.

[0041] Herein, the words "comprises" and "includes" and variations thereof mean that other elements or integers which are permitted but not specifically described may be included.

[0042] In this article, the term "and / or" is merely a term used to describe the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B may represent three situations: A exists alone, A and B exist at the same time, and B exists alone.

[0043] The embodiment of the present invention provides a method for removing impurities from mixed phenols extracted from coal tar, comprising the following steps:

[0044] S1: adding inorganic acid to the mixed phenol raw material, heating and stirring, and then continuing to heat up, while simultaneously dropping sulfuric acid during the heating process, removing water and some low-boiling substances by heat preservation, and then rectifying and dehydrating, removing residues, and obtaining dehydrated and deslagging crude phenol;

[0045] S2: adding an azeotropic agent, water and a reducing agent to the dehydrated and de-slaged crude phenol, heating and stirring, and then distilling the mixture, wherein the distillate is an azeotropic agent solution containing neutral oil, and the kettle liquid is subsequently processed;

[0046] S3: heating the kettle liquid obtained in step S2, adding alkaline substances and phase transfer catalysts, stirring for reaction, centrifuging to remove the lower alkaline water layer, heating the upper mixed phenol layer, and dripping sulfuric acid to react to obtain a mixed phenol liquid after impurities are removed; then, rectifying the mixed phenol liquid after impurities are removed to obtain various phenol fractions;

[0047] S4: recovering the entrainer in the entrainer solution containing neutral oil obtained in step S2;

[0048] S5: Mix the still residue obtained by the distillation of step S1 and the residue obtained by the distillation of step S3 and perform distillation treatment to obtain a catechol fraction with a distillation range of 242-250° C., a 5-indanol fraction with a distillation range of 253-258° C., and a resorcinol / hydroquinone fraction with a distillation range of 275-290° C.; then, post-treat the catechol fraction, the 5-indanol fraction, and the resorcinol / hydroquinone fraction, respectively, to obtain a fine catechol product, a fine 5-indanol product, a fine resorcinol product, and a fine hydroquinone product, respectively.

[0049] In view of the fact that crude phenol, especially the high-temperature distillation residue of gasified crude phenol, has a high content of catechol, the embodiment of the present invention obtains catechol fraction and resorcinol / hydroquinone fraction through distillation, and further obtains catechol fine product, resorcinol fine product and hydroquinone fine product through distillation and post-treatment, and can also extract 5-indanol fine product. Since the market of catechol products is large and the market price is high, it has high extraction value and good economic benefits.

[0050] In some embodiments, the impurity removal method also includes subjecting the trimethylol fraction among the various phenol fractions obtained in step S3 to distillation, alkylation reaction, and crystallization to obtain at least one of 3,4-dimethylphenol, 3-ethyl-5-methylphenol, 2,3,5-trimethylol, and m / p-isopropylphenol.

[0051] In some embodiments, the step S3 further includes performing a color preserving treatment on the various phenol fractions by using a color preserving agent while distilling the mixed phenol liquid after impurities removal to collect various phenol fractions;

[0052] Preferably, the color preservative includes at least one of oxalic acid, hypophosphorous acid, hydrazine hydrate and ethylenediamine.

[0053] By adding a color preservative to preserve the color of various phenol fractions, it can be ensured that the final product is a colorless to light yellow transparent liquid or solid; and the embodiment of the present invention uses a special product color preservation device to continuously add a trace amount of color preservative to the product receiving tank at a constant pressure, which can make the color preservative and the product mix more evenly, the color preservation effect is better, and the addition of the color preservative is safe and efficient.

[0054] In some embodiments, in step S1, the inorganic acid includes at least one of sulfuric acid, hydrochloric acid, and phosphoric acid, the mass fraction of the inorganic acid is 60-98%, and the amount of the inorganic acid added is 0.8-2 times the mass of the pyridine base in the mixed phenol raw material;

[0055] And / or, the amount of sulfuric acid added is 0.05 to 2 times the mass of the pyridine base in the mixed phenol raw material.

[0056] In some embodiments, in step S1, the heating and stirring temperature is 60 to 90° C., and the stirring time is 0.5 to 1 h;

[0057] And / or, the heating temperature is 120-160° C., and the heating time is 1-2 hours;

[0058] And / or, the insulation time is 1 to 2 hours.

[0059] In some embodiments, in step S2, the azeotropic agent is an alcohol amine substance or a diol substance;

[0060] Preferably, the alcoholamine substance includes at least one of ethanolamine, diethanolamine, triethanolamine, and methyldiethanolamine, and the diol substance includes at least one of ethylene glycol, diethylene glycol, propylene glycol, and butanediol;

[0061] and / or, the reducing agent comprises at least one of methylhydroxylamine, hydrazine hydrate, hydroquinone, hypophosphorous acid, phosphorous acid, oxalic acid, zinc powder, sodium borohydride, potassium borohydride, lithium aluminum hydride, and butylated hydroxyanisole;

[0062] And / or, the temperature of the heating and stirring is 50-80° C., and the stirring time is 0.5-2 h.

[0063] In some embodiments, in step S2, the amount of the azeotropic agent added is 0.5 to 10 times the mass of the neutral oil in the dehydrated and deslagging crude phenol;

[0064] And / or, the amount of water added is 0 to 10 times the mass of the neutral oil in the dehydrated and de-slaged crude phenol;

[0065] And / or, the amount of the reducing agent added is 0.01 to 0.5% of the mass of the dehydrated and de-slaged crude phenol.

[0066] In some embodiments, in step S3, the alkaline substance includes at least one of sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, sodium hydroxide, and potassium hydroxide, and the amount of the alkaline substance added is 0.5 to 3 times the mass of the organic acid in the dehydrated and deslagging crude phenol obtained in step S1;

[0067] And / or, the phase transfer catalyst is polyethylene glycol or crown ether, and the added amount of the phase transfer catalyst is 0.01-0.5% of the mass of the dehydrated and deslagging crude phenol obtained in step S1.

[0068] In step S3 of the embodiment of the present invention, sulfuric acid is added to further remove a small amount of sulfide remaining in the mixed phenol raw material, and the generated sulfide precipitate can be oxidized into sulfur by excess concentrated sulfuric acid at the same time. The sulfur and excess sulfuric acid immediately react to generate sulfur dioxide, which can reduce or eliminate the generation of sulfur that is easy to sublimate and condense and agglomerate and ferrous sulfide that is easy to self-ignite at low temperatures during the impurity removal process, thereby reducing the occurrence of safety accidents and further reducing the content of nitrogen-containing alkaline substances.

[0069] In some embodiments, in step S3, the stirring reaction temperature is 60-90° C., and the reaction time is 1-2 h;

[0070] And / or, the heating temperature is 120-160° C. and the heating time is 1-2 hours.

[0071] After the acid / base is added and reacted in steps S1 and S3 of the embodiment of the present invention, the temperature is first raised to remove water and part of the low-boiling substances, and then the residual material is distilled. This can shorten the distillation time of the material, reduce the distillation loss, and improve the utilization rate and production capacity of the distillation equipment.

[0072] In some embodiments, the specific steps of step S4 are as follows:

[0073] When the entrainer is an alcoholamine substance, the entrainer solution containing the neutral oil obtained in step S2 is heated to 30-40° C., CO2 is introduced, and then the temperature is raised to 40-50° C. for stirring and reaction. After the alcoholamine is fully salified, sampling and analysis are performed until the alcoholamine content in the neutral oil remains unchanged, and then the CO2 is stopped, and the solution is allowed to stand for stratification. Excess CO2 is pressurized and applied by a pressure pump, and the alcoholamine carbonate is separated from the neutral oil; then the alcoholamine carbonate is heated to remove CO2, the obtained alcoholamine is applied, and the recovered CO2 gas is stored after being pressurized; hydrochloric acid is added to the neutral oil to neutralize the pH to 4-6. After stratification, the water layer is an aqueous solution of alcoholamine hydrochloride, which can be used to recover the alcoholamine hydrochloride product, and the oil layer is a neutral oil layer;

[0074] When the entrainer is a diol substance, liquid alkali is added to the entrainer solution containing neutral oil obtained in step S2 to neutralize the pH to 8-9, and the solution is separated after cooling, wherein the lower layer is a sodium phenolate solution containing diols, and the upper organic layer is a mixture of methylnaphthalene and naphthalene; the sodium phenolate solution containing diols is applied to step S2 as an entrainer.

[0075] It should be noted that the various high-quality products obtained in the embodiments of the present invention all refer to products whose purity can reach 99% or above.

[0076] The technical scheme of the present invention is further described in detail below in conjunction with specific examples. Unless otherwise specified, the various raw materials used in the examples are conventional commercial products, or can be prepared by known methods; and the experimental methods without specific conditions in the examples are conventional methods and conventional conditions well known in the art.

[0077] Example 1

[0078] A method for removing impurities from mixed phenols extracted from coal tar comprises the following steps:

[0079] S1: 1000 parts of mixed phenol raw material (gasified crude phenol, containing 0.8% neutral oil (including 0.10% decahydronaphthalene, 0.06% naphthalene, 0.12% methylnaphthalene), 0.21% pyridine base, 0.22% sulfide, 3.21% organic acid (calculated as valeric acid)) are added to a reaction kettle, 2.8 parts of 60% sulfuric acid are added under stirring, the temperature is raised to 70°C and stirred for 1 hour; then the temperature is raised to 130°C within 1.5 hours, and 1 part of 85% sulfuric acid is added dropwise during the heating process, and the temperature is kept for 2 hours to remove water and part of low-boiling substances 2.2 Subsequently, the remaining material in the reactor and 2 parts of 98% sulfuric acid are transferred to a deweighting and dehydrating tower for vacuum distillation to remove water, to obtain 7.0 parts of the first part, and further distillation is performed to obtain 603 parts of dehydrated and deslagging crude phenol and 385 parts of kettle residue; wherein, the dehydrated and deslagging crude phenol is sampled and analyzed, and it contains 0.62% of neutral oil (including 0.14% of decahydronaphthalene, 0.09% of naphthalene, and 0.18% of methylnaphthalene), 0.01% of pyridine base, 0.0022% of sulfide, and 1.56% of organic acid (calculated as valeric acid, with an organic acid removal rate of 70.7%);

[0080] S2: 603 parts of dehydrated and de-slaged crude phenol are added to a stirred kettle equipped with a distillation and condensation device, and 0.02 parts of water, 0.01 parts of butylated hydroxyanisole (BHA), and 17.5 parts of ethanolamine are added under stirring, and the temperature is raised to 80° C. and stirred for 1 hour. After stirring, the material is added to a distillation tower for distillation, and the distillate is 20.8 parts of ethanolamine solution containing neutral oil (containing 3.5 parts of neutral oil, 0.5 parts of phenol, and 16.7 parts of ethanolamine), and the kettle liquid is subsequently processed;

[0081] S3: The kettle liquid obtained in step S2 is slightly cooled and then transferred into a stirring kettle equipped with a distillation condensation device, heated to 60° C., 30 parts of 20% sodium carbonate aqueous solution, 10 parts of 30% sodium hydroxide, and 0.3 parts of polyethylene glycol 400 are added three times, stirred for 1 hour, and the lower alkaline water layer containing organic acid is separated by centrifugation (the organic acid can be recovered by separate treatment), and the upper mixed phenol layer is further heated to 110° C. and 0.025 parts of 98% sulfuric acid are added, stirred and reacted for 2 hours to obtain a mixed phenol feed liquid after impurities are removed; then the mixed phenol feed liquid after impurities are removed is transferred into a rectification kettle for rectification to obtain 21.6 parts of fore fraction (containing about 6.8 parts of ethanolamine), 346 parts of phenol fraction, and 100 parts of ethanolamine. .6 parts, cresol fraction 161.1 parts, xylenol fraction 54.5 parts, tricresol fraction 13.3 parts, residue 16.9 parts; and while collecting the above fractions by rectification, a color preserving agent constant pressure dropping device is used to balance the pressure through a pressure balance tube, and then a 30% oxalic acid aqueous solution is continuously added to each fraction by a peristaltic pump to preserve the color; a small amount of each fraction is taken in proportion and mixed, and then analyzed to obtain: 3.1ppm of pyridine base, 0.05% of neutral oil (including 0.02% of decahydronaphthalene, 0.01% of naphthalene, and 0.01% of methylnaphthalene), 0.8ppm of sulfide, and 0.02% of organic acid (calculated as valeric acid), indicating that the impurity removal effect is good;

[0082] S4: adding 20.8 parts of the ethanolamine solution containing neutral oil obtained in step S2 to a stirred kettle with a distillation and condensation device, heating to 35°C, and introducing 19 parts of carbon dioxide within 2 hours, and then heating to 45°C and stirring for reaction for 2 hours to fully salt the ethanolamine, sampling and analysis, the ethanolamine content in the neutral oil layer decreases very slowly, stopping the introduction of carbon dioxide, standing and stratifying, and pressurizing the excess carbon dioxide to 0.3MPa by a pressure pump and storing it in a carbon dioxide storage tank for application, ethanolamine carbonate is separated from the neutral oil to obtain 3.9 parts of neutral oil; then adding the separated ethanolamine carbonate to a stirred kettle with a distillation and condensation device, heating to 95°C to remove carbon dioxide, and obtaining 16.2 parts of ethanolamine for application, and recovering a total of 11.6 parts of carbon dioxide gas, which is pressurized to 0.3MPa by a pressure pump and stored in a carbon dioxide storage tank for application, with an ethanolamine recovery rate of 92.57%;

[0083] Add 1 part of 31% hydrochloric acid to the 3.9 parts of the separated neutral oil layer, and separate the layers to obtain 1.55 parts of an aqueous solution containing 0.8 parts of ethanolamine hydrochloride and 3.3 parts of neutral oil; wherein the aqueous solution of ethanolamine hydrochloride is concentrated and used to extract ethanolamine hydrochloride, a pharmaceutical intermediate, and the neutral oil is used to extract naphthalene and methylnaphthalene (1-methylnaphthalene and 2-methylnaphthalene), or used as dephenolized phenol oil (which can be hydrogenated to produce gasoline and diesel);

[0084] 155 parts of aqueous solution of ethanolamine hydrochloride (containing 80 parts of ethanolamine hydrochloride) obtained after 100 batches were concentrated were added to a reaction kettle, and the temperature was raised under stirring to evaporate 7.2 parts of residual neutral oil, and then 1.5 parts of activated carbon were added to the aqueous solution and stirred for decolorization for 1 hour, and then the temperature was lowered to 80°C for filtration, and the filter residue was treated as hazardous waste in a centralized manner. The filtrate was then filtered through a two-stage macroporous resin column to remove impurities, and finally flash distillation was performed to obtain 76.9 parts of ethanolamine hydrochloride with a content of 98.6%, a yield of 94.78%, and a total yield of ethanolamine of 97% (including recovered ethanolamine and ethanolamine hydrochloride);

[0085] S5: 385 parts of the still residue obtained by the distillation of step S1 and 16.9 parts of the residue obtained by the distillation of step S3 (a total of 401.9 parts) are added to the distillation still for distillation treatment (the fraction before distillation at 290°C in the laboratory is taken, accounting for 67.3% of the residue, about 270 parts; the raw material composition of the chromatographic analysis is: 10.32% of catechol, 21.62% of resorcinol, 30.55% of hydroquinone, 15.51% of methylbenzene, 10.8% of 5-indanol) 4%, naphthol 0.53%, tetrahydronaphthol 1.58%, others 9.05%), distilled to obtain 32.5 parts of catechol fraction with a distillation range of 242-250°C (containing 81.2% of catechol), 28.6 parts of 5-indanol fraction with a distillation range of 253-258°C (containing 86.5% of 5-indanol), and 153.5 parts of resorcinol / hydroquinone fraction with a distillation range of 275-290°C (containing 35.75% of resorcinol and 51.59% of hydroquinone);

[0086] 32.5 parts of catechol fraction (containing 81.2% catechol) were distilled at -0.095 MPa and reflux ratio 20:1 to obtain 19.3 parts of 99.1% catechol fine product with a yield of 72.5%;

[0087] 28.6 parts of 5-indanol fraction were added to the reactor and stirred, and 30 parts of 95% ethanol were added, and the temperature was raised to 80°C. After the material was dissolved, 0.25 parts of activated carbon were added and kept warm for 1 hour, filtered, and the filter cake was washed with 2 parts of ethanol, drained, and the filter cake was centrally processed. The filtrate and washing liquid were combined and added to the concentrated crystallization kettle, and the temperature was raised to remove 16.2 parts of ethanol; then the steam in the jacket was pressed out, and circulating water was passed for 3 hours to cool to 35°C, the circulating water was pressed out, and ice brine was passed for 2 hours to cool to 0°C, and the temperature was kept warm for 1 hour, filtered, and the filter cake was washed with ethanol at 0°C. The obtained filter cake was dried under reduced pressure at 30°C, and finally 18 parts of 99.1% 5-indanol fine products were obtained, and the crystallization yield was 72.1%;

[0088] 153.5 parts of resorcinol / hydroquinone fraction (containing 35.75% resorcinol and 51.59% hydroquinone) were distilled at -0.095 MPa and a reflux ratio of 20:1 to obtain 52 parts of crude resorcinol (containing 87.8% resorcinol) and 78.5 parts of crude hydroquinone (containing 86.9% hydroquinone); the extraction rate of resorcinol was 83.3%, and the extraction rate of hydroquinone was 86.1%; then 104 parts of ethyl acetate (containing 5% water) were added to 52 parts of crude resorcinol (containing 87.8% resorcinol and 8.3% hydroquinone), the temperature was raised to 60°C to completely dissolve the material, the temperature was lowered to room temperature in 3 hours, ice brine was added to lower the temperature to 15°C in 1 hour, the temperature was kept for 1 hour, filtered, and dried to obtain 40.7 parts of 99.2% resorcinol fine product, and the resorcinol fine product was collected. The rate is 88.4%, and the mother liquor is used for the next distillation after the solvent is recovered. The material is incorporated into the 275-290°C isoquinone / hydroquinone section for the next distillation, and the recovered ethyl acetate is used; 108 parts of water are added to 78.5 parts of crude hydroquinone (hydroquinone content 86.9%, resorcinol 10.3%), and the temperature is raised to 80°C to completely dissolve the material, and then the material is cooled to 35°C in a water bath, and then the water bath is removed and naturally cooled to room temperature. A large amount of material is precipitated, filtered, and dried to obtain 62.7 parts of 99.5% hydroquinone fine products, with a crystallization yield of 91.5%. The aqueous solution is extracted with 52.5 parts of isobutyl acetate three times (17.5 parts each time), and the water layer is used as a solvent. The material after the solvent layer recovers the solvent is incorporated into the 275-290°C isoquinone / hydroquinone section for the next distillation, and the recovered isobutyl acetate is used;

[0089] S6: After collecting 100 batches of the trimethylol fraction obtained in step S3, 1330 portions of liquid are obtained and transferred to a rectification kettle (including 0.68% of 3,5-dimethylphenol, 0.12% of m-p-ethylphenol, 19.22% of 3,4-dimethylphenol, 0.89% of 2,4 / 2,5-methylethylphenol, 13.53% of m-p-isopropylphenol, 1.59% of 2-ethyl-3-methylphenol, 32.02% of 3-ethyl-5-methylphenol, 22.89% of 2,3,5-trimethylphenol, 1.67% of 2,4,5-trimethylphenol, and 1.67% of 3-methylphenol). -4-ethylphenol 3.23%, catechol 1.51%, 5-indanol 0.58%, others 2.07%), and added 2 parts of 98% sulfuric acid for distillation (-0.085MPa, reflux ratio of 20:1), to obtain 197.6 parts of 3,4-dimethylphenol crude fraction (containing 3,5-dimethylphenol 4.5%, m-p-ethylphenol 0.76%, 3,4-dimethylphenol 86.12%, 2,3,5-trimethylphenol 0.19%, 3-ethyl-5-methylphenol 0.27%, 2,4 / 2,5-methylethyl phenol 5.92%, others 2.24%), 138.4 parts of transition fractions (containing 3,4-dimethylphenol 31.57%, 3-ethyl-5-methylphenol 20.66%, m- / p-isopropylphenol 23.48%, 2-ethyl-3-methylphenol 6.50%, 2,4,5-trimethylphenol 1.45%, 2,3,5-trimethylphenol 11.34%), 887.1 parts of trimethylphenol (containing 3,4-dimethylphenol 3.4%, 3-ethyl-5-methylphenol 43.11%, m / p-isopropylphenol 15.52%, 2-ethyl-3-methylphenol 6.50%, 2,4,5-trimethylphenol 1.45%, 2,3,5-trimethylphenol 11.34%). -cresol 1.32%, 2,4,5-trimethylphenol 2.12%, 2,3,5-trimethylphenol 29.84%, others 1.42%), 95.6 parts of kettle residue (containing 2-ethyl-3-methylphenol 0.21%, 2,4,5-trimethylphenol 1.28%, m-isopropylphenol 0.11%, 3-ethyl-5-methylphenol 11.97%, 2,3,5-trimethylphenol 23.4%, 3-ethyl-4-methylphenol 35.68%, catechol 18.06%, 5-indanol 6.41%, others 2.81%);

[0090] 1200 parts of petroleum ether were added to the above 197.6 parts of crude 3,4-xylenol fraction, the temperature was raised to 80°C to dissolve the material, the temperature was kept for 1 hour, the temperature was lowered to 30°C for 3 hours, the temperature was lowered to 15°C with frozen brine for 2 hours, the temperature was kept for 2 hours, the product was filtered, and the product was washed with 50 parts of 10°C petroleum ether, and 142.4 parts of 98.6% 3,4-xylenol were obtained after drying, and the refined yield was 82.5%; then 100 parts of methanol were added to 142.4 parts of 98.6% 3,4-xylenol, the temperature was raised to 60°C to dissolve, the temperature was kept for 1 hour, the temperature was lowered to 30°C for 2 hours, the temperature was lowered to -5°C with frozen brine for 3 hours, the temperature was kept for 2 hours, the product was filtered, the product was washed with 4 parts of -5°C methanol, and 130.7 parts of 99.8% 3,4-xylenol were obtained after drying, and the recrystallization yield was 92.9%, and the total crystallization yield was 76.65%;

[0091] The above 887.1 parts of trimethylol were subjected to alkylation reaction, distillation and solvent crystallization to obtain 270.5 parts of 99.4% 3-ethyl-5-methylphenol (yield 70.3%), 171.9 parts of 99.3% 2,3,5-trimethylol (yield 64.5%) and 128.9 parts of 99.1% m / p-isopropylphenol.

[0092] Example 2

[0093] S1: 1000 parts of mixed phenol raw material (crude phenol obtained by solvent extraction of phenol-containing phenol oil obtained by medium-low temperature coal tar fractionation) are added to a reactor, and sampling and determination show that it contains 2.2% of neutral oil (including 0.32% of decahydronaphthalene, 0.85% of naphthalene, and 0.45% of methylnaphthalene), 0.52% of pyridine base, 0.53% of sulfide, and 0.55% of organic acid (calculated as valeric acid); 7 parts of 70% sulfuric acid are added to the mixed phenol raw material under stirring, and the temperature is raised to 70°C and stirred for 1 hour, and then the temperature is raised to 130°C in 1.5 hours, and 4 parts of 9 8% sulfuric acid, heat preservation for 2 hours to remove water and 3.8 parts of some low-boiling substances; then transfer the remaining materials in the reactor to a deweighting and dehydrating tower for vacuum distillation to remove water to obtain 7.5 parts of the first part, and continue distillation to obtain 812 parts of dehydrated and deslagging crude phenol and 183 parts of kettle residue; wherein, the dehydrated and deslagging crude phenol is sampled and analyzed, and it contains 1.68% of neutral oil (including 0.38% of decahydronaphthalene, 0.93% of naphthalene, and 0.11% of methylnaphthalene), 0.12% of pyridine base, 0.33% of sulfide, and 0.38% of organic acid (calculated as valeric acid, the organic acid removal rate is 43.9%);

[0094] S2: 812 parts of dehydrated and de-slaged crude phenol are added to a stirred kettle equipped with a distillation and condensation device, 3 parts of water, 17.9 parts of ethanolamine and 0.1 parts of hydroquinone are added under stirring, the temperature is raised to 80° C. and stirred for 1 hour, after stirring, the material is added to a distillation tower for distillation, and the distillate is 36.2 parts of ethanolamine solution containing neutral oil, and the kettle liquid is subsequently processed;

[0095] S3: The kettle liquid obtained in step S2 is slightly cooled and then transferred to a stirred kettle with a distillation condensation device, heated to 60 ℃, 3.1 parts of sodium carbonate, 1.6 parts of sodium hydroxide, and 11 parts of water are added three times, and 0.4 parts of 50% polyethylene glycol aqueous solution are added simultaneously, and the temperature is raised to 80 ℃ and stirred for reaction for 2 hours, and the lower alkaline water layer containing organic acid is removed by centrifugation (the organic acid can be separately processed and recovered), and the upper mixed phenol layer is continuously heated to 120 ℃ within 2 hours, and 2.4 parts of sulfuric acid and 50% copper sulfate aqueous solution are added during the temperature rise process, and 12.9 parts (containing a trace of ethanolamine) are dehydrated, and the remaining feed liquid is transferred to a rectifying kettle for rectification to obtain 322.4 parts of phenol fractions; when the phenol fraction collection is almost finished, a sample is taken to observe the color of phenol, and it is found that the color of phenol turns red after being placed, and the reagent configuration tank and the vacuum balance pipe of the rectifying tower reactor in the reagent constant pressure dripping device are opened, and the bottom valve of the reagent configuration tank is opened to the rectifying tower reactor after pressure balance. 0.8 parts of 93% sulfuric acid was added dropwise, and the whole reflux was continued for 1 hour, and 282.5 parts of cresol fraction, 160.8 parts of xylenol fraction, 39.8 parts of trimethylol fraction and 9.8 parts of residue were collected in sequence. During the distillation, samples were taken every hour to observe the color of the distilled samples and analyze the content of the samples. The color of the distilled samples was colorless to light yellow. While collecting the phenol, cresol fraction and xylenol fraction by distillation, the pressure was balanced by the pressure balance tube, and the peristaltic pump was used to continuously and sequentially 0.02, 0.0025 and 0.002 parts of hydrazine solution were added to the phenol fraction, the cresol fraction and the xylenol fraction respectively to preserve the color; a small amount of each fraction was taken in proportion and mixed and analyzed to obtain: 2.3ppm of pyridine base, 0.18% of neutral oil (including 0.05% of decahydronaphthalene, 0.03% of naphthalene and 0.03% of methylnaphthalene), 1.8ppm of sulfide and 0.02% of organic acid (calculated as valeric acid), indicating that the impurity removal effect was good;

[0096] S4: adding 36.2 parts of the ethanolamine solution containing neutral oil obtained in step S2 into a stirred kettle with a distillation condensation device and heating it to 40° C., and introducing 24 parts of carbon dioxide within 2 hours to fully salt the ethanolamine, stirring and reacting at 50° C. for 2 hours after the introduction, reacting for 2 hours, taking samples for analysis, the ethanolamine content in the neutral oil layer decreases very slowly, stopping the introduction of carbon dioxide, standing and stratifying, and pressurizing the excess carbon dioxide to 0.3 MPa by a pressure pump and storing it in a carbon dioxide storage tank for application, and separating ethanolamine carbonate from the neutral oil to obtain 15.9 parts of neutral oil; then adding the separated ethanolamine carbonate to a stirred kettle with a distillation condensation device, heating to 95° C. to remove carbon dioxide to obtain 17.1 parts of ethanolamine for application, and pressurizing the recovered carbon dioxide gas to 0.3 MPa by a pressure pump and storing it in a carbon dioxide storage tank for application, and the ethanolamine recovery rate is 95.5%;

[0097] 0.9 parts of 31% hydrochloric acid are added to 15.9 parts of the separated neutral oil, and the separated oil is separated into layers to obtain 1.4 parts of an aqueous solution containing 0.71 parts of ethanolamine hydrochloride and 15.4 parts of neutral oil; wherein the aqueous solution of ethanolamine hydrochloride is concentrated and used to extract ethanolamine hydrochloride, a pharmaceutical intermediate, and 15.4 parts of the neutral oil are used to extract naphthalene and methylnaphthalene (1-methylnaphthalene and 2-methylnaphthalene), or used as dephenolized phenol oil (which can be hydrogenated to produce gasoline and diesel); together with the ethanolamine extracted and utilized from the ethanolamine hydrochloride, the total recovery rate of ethanolamine is 98.0%;

[0098] 140 parts of aqueous solution of ethanolamine hydrochloride (containing 71 parts of ethanolamine hydrochloride) obtained after 100 batches were concentrated were added to the reaction kettle, and the temperature was raised under stirring to evaporate 0.6 parts of residual neutral oil, and then 1 part of activated carbon was added to the aqueous solution of ethanolamine hydrochloride and stirred for decolorization for 1 hour, and then the temperature was lowered to 80°C and filtered, and the filter residue was centrally treated as hazardous waste, and the filtrate was filtered through a two-stage macroporous resin column to remove impurities, and finally flash distillation was performed to obtain 58.7 parts of ethanolamine hydrochloride with a content of 98.3%, and the yield was 81.3%;

[0099] S5: 183 parts of the still residue obtained by the distillation of step S1 and 9.8 parts of the residue obtained by the distillation of step S3 (a total of 192.8 parts) are mixed and added into a distillation still for distillation treatment (the fraction before distillation at 290°C in the laboratory is taken, accounting for 66.9% of the residue, about 129 parts; the raw material composition of the chromatographic analysis is: containing 11.34% of catechol, 21.26% of resorcinol, 30.03% of hydroquinone, 15.37% of 5-indanol, 10 .38%, naphthol 0.48%, tetrahydronaphthol 1.46%, others 9.68%), distilled to obtain 17 parts of catechol fraction with a distillation range of 242-250°C (containing 82.3% of catechol), 13.4 parts of 5-indanol fraction with a distillation range of 253-258°C (containing 84.9% of 5-indanol), and 72.5 parts of resorcinol / hydroquinone fraction with a distillation range of 275-290°C (containing 35.59% of resorcinol and 51.03% of hydroquinone);

[0100] 17 parts of catechol fraction (containing 82.3% catechol) were distilled at -0.095 MPa and reflux ratio 20:1 to obtain 10.4 parts of 99.2% catechol fine product with a yield of 73.7%;

[0101] 13.4 parts of 5-indanol fraction were added to the reactor and stirred, and 15 parts of 95% ethanol were added, and the temperature was raised to 80°C. After the material was dissolved, 0.15 parts of activated carbon were added and kept warm for 1 hour, filtered, and the filter cake was washed with 1 part of ethanol, drained, and the filter cake was centrally processed. The filtrate and washing liquid were combined and added to the concentrated crystallization kettle, and the temperature was raised to remove 8 parts of ethanol; then the steam in the jacket was pressed out, and circulating water was passed for 3 hours to cool to 35°C, the circulating water was pressed out, and ice brine was passed for 2 hours to cool to 0°C, and the temperature was kept warm for 1 hour, filtered, and the filter cake was washed with ethanol at 0°C. The obtained filter cake was dried under reduced pressure at 30°C, and finally 8 parts of 99.3% 5-indanol fine products were obtained, and the crystallization yield was 70.1%;

[0102] 72.5 parts of resorcinol / hydroquinone fraction (containing 35.59% resorcinol and 51.03% hydroquinone) were distilled at -0.095 MPa and a reflux ratio of 20:1 to obtain 24.1 parts of crude resorcinol (containing 87.1% resorcinol) and 36.7 parts of crude hydroquinone (containing 86.3% hydroquinone); the extraction rate of resorcinol was 81.5%, and the extraction rate of hydroquinone was 85.6%; then 50 parts of ethyl acetate (containing 5% water) were added to 24.1 parts of crude resorcinol (containing 87.1% resorcinol and 8.8% hydroquinone), the temperature was raised to 60°C to completely dissolve the material, the temperature was lowered to room temperature in 3 hours, ice salt water was added to lower the temperature to 15°C in 1 hour, the temperature was kept for 1 hour, filtered, and dried to obtain 18.6 parts of 99.1% resorcinol concentrate The product was obtained, and the yield of fine hydroquinone was 87.8%. After the mother liquor recovered the solvent, the material was incorporated into the 275-290°C hydroquinone / hydroquinone distillation section for the next distillation, and the recovered ethyl acetate was used; 50 parts of water were added to 36.7 parts of crude hydroquinone (hydroquinone content 86.3%), the temperature was raised to 80°C to completely dissolve the material, and then the material was cooled to 35°C in a water bath, and then the water bath was removed and naturally cooled to room temperature. A large amount of material was precipitated, filtered, and dried to obtain 28.6 parts of 99.3% hydroquinone fine products, with a crystallization yield of 89.7%. The aqueous solution was extracted with 21 parts of isobutyl acetate three times (7 parts each time), and the water layer was used as a solvent. The material after the solvent layer recovered the solvent was incorporated into the 275-290°C hydroquinone / hydroquinone distillation section for the next distillation, and the recovered isobutyl acetate was used;

[0103] S6: After the trimethylol fraction obtained in step S3 is concentrated into 35 batches, 1393 portions of liquid are obtained and transferred into a rectification kettle (including 0.54% of 3,5-dimethylphenol, 0.08% of m-p-ethylphenol, 18.88% of 3,4-dimethylphenol, 0.62% of 2,4 / 2,5-methylethylphenol, 14.15% of m-p-isopropylphenol, 1.48% of 2-ethyl-3-methylphenol, 32.33% of 3-ethyl-5-methylphenol, 23.16% of 2,3,5-trimethylphenol, 1.53% of 2,4,5-trimethylphenol, 3-methyl-4- 3,4-dimethylphenol (containing 3.73% 3,5-dimethylphenol, 0.55% m-p-ethylphenol, 88.31% 3,4-dimethylphenol, 0.08% 2,3,5-trimethylphenol, 0.19% 3-ethyl-5-methylphenol, 4.29% 2,4 / 2,5-methylethylphenol) was obtained. %, others 2.85%), 139.2 parts of transition fractions (containing 3,4-dimethylphenol 36.57%, 3-ethyl-5-methylphenol 20.48%, m- / p-isopropylphenol 23.61%, 2-ethyl-3-methylphenol 5.63%, 2,4,5-trimethylphenol 1.32%, 2,3,5-trimethylphenol 11.34%, others 1.05%), 890.8 parts of trimethylphenols (containing 3,4-dimethylphenol 3.86%, 3-ethyl-5-methylphenol 42.86%, m- / p-isopropylphenol 18.17%, 2-ethyl-3-methylphenol 3-Cresol 1.26%, 2,4,5-trimethylphenol 1.83%, 2,3,5-trimethylphenol 30.86%, others 1.16%), 150.7 parts of kettle residue (containing 2-ethyl-3-methylphenol 0.79%, 2,4,5-trimethylphenol 1.99%, m-isopropylphenol 0.13%, 3-ethyl-5-methylphenol 23.29%, 2,3,5-trimethylphenol 18.91%, 3-ethyl-4-methylphenol 18.84%, catechol 14.8%, 5-indanol 5.64%, others 15.61%);

[0104] 1200 parts of petroleum ether were added to the above 198.3 parts of crude 3,4-xylenol fraction, the temperature was raised to 80°C to dissolve the material, the temperature was kept for 1 hour, the temperature was lowered to 30°C for 3 hours, the temperature was lowered to 15°C with frozen brine for 2 hours, the temperature was kept for 2 hours, the mixture was filtered, and the mixture was washed with 50 parts of 10°C petroleum ether, and 143.7 parts of 99.1% 3,4-xylenol were obtained after drying, and the refining yield was 81.3%;

[0105] The above 890.8 parts of trimethylol were subjected to alkylation reaction, distillation and solvent crystallization to obtain 271.7 parts of 99.5% 3-ethyl-5-methylphenol fine product (yield 70.8%), 182.3 parts of 99.2% 2,3,5-trimethylol fine product (yield 65.8%), and 130.1 parts of 99.3% m / p-isopropylphenol fine product.

[0106] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" etc. mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0107] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A method for removing impurities from mixed phenols extracted from coal tar, characterized in that: The steps include: S1: adding inorganic acid to the mixed phenol raw material, heating and stirring, and then continuing to heat up, while simultaneously dropping sulfuric acid during the heating process, removing water and some low-boiling substances by heat preservation, and then rectifying and dehydrating, removing residues, and obtaining dehydrated and deslagging crude phenol; S2: adding an azeotropic agent, water and a reducing agent to the dehydrated and de-slaged crude phenol, heating and stirring, and then distilling the mixture, wherein the distillate is an azeotropic agent solution containing neutral oil, and the kettle liquid is subsequently processed; S3: heating the kettle liquid obtained in step S2, adding alkaline substances and phase transfer catalysts, stirring for reaction, centrifuging to remove the lower alkaline water layer, heating the upper mixed phenol layer, and dripping sulfuric acid to react to obtain a mixed phenol liquid after impurities are removed; then, rectifying the mixed phenol liquid after impurities are removed to obtain various phenol fractions; S4: recovering the entrainer in the entrainer solution containing neutral oil obtained in step S2; S5: Mix the still residue obtained by the distillation of step S1 and the residue obtained by the distillation of step S3 and perform distillation treatment to obtain a catechol fraction with a distillation range of 242-250° C., a 5-indanol fraction with a distillation range of 253-258° C., and a resorcinol / hydroquinone fraction with a distillation range of 275-290° C.; then, the catechol fraction, the 5-indanol fraction, and the resorcinol / hydroquinone fraction are post-treated to obtain a fine catechol product, a fine 5-indanol product, a fine resorcinol product, and a fine hydroquinone product, respectively.

2. The method for removing impurities from the mixed phenol extracted from coal tar according to claim 1, characterized in that: The method also includes subjecting the trimethylol fraction among the various phenol fractions obtained in step S3 to distillation, alkylation reaction and crystallization to obtain at least one product of 3,4-dimethylphenol, 3-ethyl-5-methylphenol, 2,3,5-trimethylol and m / p-isopropylphenol.

3. The method for removing impurities from the mixed phenol extracted from coal tar according to claim 1, characterized in that: The step S3 further includes performing a color preserving treatment on the various phenol fractions by using a color preserving agent while distilling the mixed phenol liquid after impurities removal to collect various phenol fractions; Preferably, the color preservative includes at least one of oxalic acid, hypophosphorous acid, hydrazine hydrate and ethylenediamine.

4. The method for removing impurities from mixed phenols extracted from coal tar according to claim 1, characterized in that: In the step S1, the inorganic acid includes at least one of sulfuric acid, hydrochloric acid and phosphoric acid, the mass fraction of the inorganic acid is 60-98%, and the amount of the inorganic acid added is 0.8-2 times the mass of the pyridine base in the mixed phenol raw material; And / or, the amount of sulfuric acid added is 0.05 to 2 times the mass of the pyridine base in the mixed phenol raw material.

5. The method for removing impurities from mixed phenols extracted from coal tar according to claim 1, characterized in that: In step S1, the heating and stirring temperature is 60 to 90° C., and the stirring time is 0.5 to 1 h; And / or, the heating temperature is 120-160° C., and the heating time is 1-2 hours; And / or, the insulation time is 1 to 2 hours.

6. The method for removing impurities from mixed phenols extracted from coal tar according to claim 1, characterized in that: In the step S2, the entrainer is an alcohol amine substance or a diol substance; Preferably, the alcoholamine substance includes at least one of ethanolamine, diethanolamine, triethanolamine, and methyldiethanolamine, and the diol substance includes at least one of ethylene glycol, diethylene glycol, propylene glycol, and butanediol; and / or, the reducing agent comprises at least one of methylhydroxylamine, hydrazine hydrate, hydroquinone, hypophosphorous acid, phosphorous acid, oxalic acid, zinc powder, sodium borohydride, potassium borohydride, lithium aluminum hydride, and butylated hydroxyanisole; And / or, the temperature of the heating and stirring is 50-80° C., and the stirring time is 0.5-2 h.

7. The method for removing impurities from mixed phenols extracted from coal tar according to claim 1, characterized in that: In the step S2, the amount of the azeotropic agent added is 0.5 to 10 times the mass of the neutral oil in the dehydrated and deslagging crude phenol; And / or, the amount of water added is 0 to 10 times the mass of the neutral oil in the dehydrated and de-slaged crude phenol; And / or, the amount of the reducing agent added is 0.01 to 0.5% of the mass of the dehydrated and de-slaged crude phenol.

8. The method for removing impurities from mixed phenols extracted from coal tar according to claim 1, characterized in that: In step S3, the alkaline substance includes at least one of sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, sodium hydroxide, and potassium hydroxide, and the amount of the alkaline substance added is 0.5 to 3 times the mass of the organic acid in the dehydrated and deslagging crude phenol obtained in step S1; And / or, the phase transfer catalyst is polyethylene glycol or crown ether, and the added amount of the phase transfer catalyst is 0.01-0.5% of the mass of the dehydrated and deslagging crude phenol obtained in step S1.

9. The method for removing impurities from mixed phenols extracted from coal tar according to claim 1, characterized in that: In step S3, the stirring reaction temperature is 60-90° C., and the reaction time is 1-2 h; And / or, the heating temperature is 120-160° C. and the heating time is 1-2 hours.

10. The method for removing impurities from mixed phenols extracted from coal tar according to claim 1, characterized in that: The specific steps of step S4 are as follows: When the entrainer is an alcoholamine substance, the entrainer solution containing the neutral oil obtained in step S2 is heated to 30-40°C, CO2 is introduced, and then the temperature is raised to 40-50°C for stirring and reaction. After the alcoholamine is fully salified, sampling and analysis are performed until the alcoholamine content in the neutral oil remains unchanged, the CO2 is stopped, and the solution is allowed to stand for stratification. Excess CO2 is pressurized and applied by a pressure pump, and the alcoholamine carbonate is separated from the neutral oil; then the alcoholamine carbonate is heated to remove CO2, the obtained alcoholamine is applied, and the recovered CO2 gas is stored after being pressurized; hydrochloric acid is added to the neutral oil to neutralize the pH to 4-6. After stratification, the water layer is an aqueous solution of alcoholamine hydrochloride, and the oil layer is a neutral oil layer; When the entrainer is a diol substance, liquid alkali is added to the entrainer solution containing neutral oil obtained in step S2 to neutralize the pH to 8-9, and the solution is separated after cooling, wherein the lower layer is a sodium phenolate solution containing diols, and the upper organic layer is a mixture of methylnaphthalene and naphthalene; the sodium phenolate solution containing diols is applied to step S2 as an entrainer.