Method for producing alkyl etherate from o-cresol post-fraction carbolic oil fraction

Abstract

The invention belongs to the field of coal coking and production and separation of organic chemical products, and particularly relates to a method for producing alkyl etherates from o-cresol post-fraction carbolic oil fraction. The invention provides a method for producing alkyl etherate from o-cresol post-fraction phenol oil fraction, which comprises the following steps: rectifying phenol-containing coal tar to obtain the o-cresol post-fraction phenol oil fraction at 192-195 DEG C, extracting the o-cresol post-fraction phenol oil fraction by using aqueous alkali to obtain upper-layer dephenolized phenol oil and aqueous-layer phenol sodium salt solution, and separating the upper-layer dephenolized phenol oil from the aqueous-layer phenol sodium salt solution to obtain the alkyl etherate. The method comprises the following steps of: heating to remove impurities such as neutral oil in a sodium phenolate aqueous solution, performing etherification reaction with an alkylating agent to obtain water-insoluble o-methyl benzene alkyl ether and 2, 6-dimethyl benzene alkyl ether, and rectifying to obtain high-purity o-methyl benzene alkyl ether and 2, 6-dimethyl benzene alkyl ether. According to the method, the reaction conditions are mild, only etherates are generated in the reaction process, side reactions of alkylation and dealkylation on benzene rings are basically avoided, and the etherification selectivity is good.

Description

Technical Field

[0001] The invention belongs to the field of coal coking and production and separation of organic chemical products, and in particular relates to a method for producing alkyl ethers from o-cresol post-fraction phenol oil fractions. Background Art

[0002] Fractionation or rectification of phenolic coal tar can obtain a phenol oil fraction (191-195°C) rich in o-cresol, which mainly contains o-cresol and 2,6-xylenol, with a low content of m-cresol. Since the boiling points of o-cresol, 2,6-xylenol and m-cresol are 191°C, 203°C and 202°C, respectively, the boiling point difference is very small. 2,6-xylenol can only be partially separated from o-cresol and m-cresol in an efficient distillation tower, and the obtained product is mainly a mixture with little pure product. The phenol oil fraction of the post-ortho-cresol fraction cannot be further purified to produce ortho-cresol, making its price much lower than 99.5% refined ortho-cresol and 99% 2,6-xylenol. Therefore, the economic benefits of using the phenol oil fraction of the post-ortho-cresol fraction to replace refined ortho-cresol and pure 2,6-xylenol to produce the corresponding alkyl ethers are very considerable. At the same time, the dephenolized phenol oil can be separated from the post-ortho-cresol fraction, and the dephenolized phenol oil can be hydrogenated to produce gasoline and diesel.

[0003] Patent CN109942383A of Dalian Institute of Chemical Physics, Chinese Academy of Sciences, discloses a method for producing mixed ether by gas phase etherification of mixed phenol and methanol, which comprises at least the following steps: passing a mixture containing mixed phenol (phenol before crude phenol distillation at 220°C, various cresols, at least two of various xylenols) and methanol through a reaction zone containing an etherification catalyst to react and obtain ether. The method for producing mixed ether by mixed phenol and methanol uses mixed phenol and methanol as raw materials, the selectivity of etherification products can reach more than 98%, and the catalyst has good stability; and there is no equipment corrosion during the production process, and it is an environmentally friendly catalyst with good industrial application prospects. The reaction temperature used in the invention is above 250°C, and the reaction needs to be carried out at a low mixed phenol conversion rate to ensure high etherification selectivity (the conversion rate is generally 20-50%), with low single-pass yield, high energy consumption, and high production cost; at the same time, the reaction generates anisole, various methyl anisole, various dimethyl anisole, a small amount of trimethyl anisole, phenol, various cresols, various xylenols, and various trimethylphenols (methylation reaction also occurs on the benzene ring during etherification to generate phenol with one more methyl group; cresols and xylenols are easy to undergo transposition reaction at high temperature and in the presence of molecular sieve catalysts). Due to the high temperature, diphenyl ether and its homologues will inevitably be formed between phenols, and the composition is very complex: for example, the reaction of phenol, o-cresol, 2,6-dimethylphenol, and m-p-cresol with methanol will produce anisole, o-methylbenzyl ether, m-methylbenzyl ether, p-methylbenzyl ether, and 2,6-dimethylbenzyl ether. At the same time, various cresols, various dimethylphenols (2,6- / 2,4- / 2,5- / 2,3- / 3,5- / 3,4-dimethylphenol), and various trimethylphenols (mainly 2,4,6-trimethylphenol, 2,3,6-trimethylphenol, etc.) will also be produced. These phenolic products will Etherification generates 2,4- / 2,5- / 3,4- / 3,5- / 2,3-dimethylanisole, 2,4,6- / 2,3,6- / 2,3,5-trimethylanisole and other substances, so the reaction product is a mixture of the above substances; the boiling points of each substance are respectively m-p-methylanisole (boiling point at 175-176°C), o-methylbenzyl ether 171°C, 2,6-dimethylanisole 182°C (phenol 182°C), 2,4- / 2,5-dimethylanisole 190-192°C (o-cresol 191°C), 2,3- / 3,5-dimethylanisole 1 94~195℃ (o-cresol 191℃), 3,4-dimethylanisole 203℃ (m-cresol 201~202℃), 2,4,6-trimethylanisole 205.8℃ (m-cresol 201~202℃, o-ethylphenol 204.5℃), 2,3,5-trimethylanisole 220℃ (m-ethylphenol 218~219℃, 3,5-dimethylphenol 220℃), so it is very difficult to separate the etherified products from the phenolic products by distillation. Only the etherification catalyst with very good selectivity can extract the mixed anisole products at a low conversion rate.

[0004] When the phenol-containing coal tar is hydrogenated to produce gasoline and diesel, the presence of phenolic materials consumes a large amount of hydrogen, the hydrogen consumption is too high, and the production cost increases more; the hydrogenation reaction produces a large amount of water, which can cause the hydrogenation catalyst to run off and harden, seriously affecting the catalyst life and easily leading to production failures, so the crude phenol in the phenol oil needs to be extracted before the phenol-containing coal tar is hydrogenated. A common method is to extract the crude phenol (the abbreviation of the mixture of various phenolic substances) in the phenol oil with alkaline water, and then neutralize it with sulfuric acid, and stand for stratification to obtain a 10% water-containing crude phenol, and produce a large amount of phenol-containing, sodium sulfate-containing high-salt waste water, which has been clearly eliminated; in addition, the solvent extraction method currently being developed uses an alcohol amine solvent to extract the crude phenol in the phenol-containing phenol oil or the phenol-containing coal tar, which has many steps and high operating costs, and there is no very successful industrial application in China at present.

[0005] Therefore, how to use phenol-containing coal tar to prepare the corresponding alkyl ethers and reduce the cost of hydrogenating them to produce gasoline and diesel has received increasing attention. Summary of the invention

[0006] The present invention is based on the inventor's discovery and understanding of the following facts and problems:

[0007] o-Methylbenzyl ether and 2,6-dimethylanisole are important organic synthesis intermediates, which are usually prepared by using expensive refined o-cresol and pure 2,6-dimethylphenol. However, it is difficult to further purify the phenol oil fraction of o-cresol to obtain 99.5% refined o-cresol through distillation, and it is often sold at a low price or disposed of as waste, and is not used reasonably.

[0008] The prior art method requires a low mixed phenol conversion rate to ensure high etherification selectivity, low single-pass yield, high energy consumption, and high production cost. In addition, the product composition generated by the method is very complex, and it is very difficult to separate the etherified product by distillation. Therefore, the method is difficult to promote and apply in industry.

[0009] The present invention aims to solve at least one of the technical problems in the related art to a certain extent. To this end, the embodiment of the present invention provides a method for producing alkyl ethers from a phenol oil fraction of an o-cresol fraction, wherein the reaction conditions are mild, only ethers are produced during the reaction, and the side reactions of alkylation and dealkylation on the benzene ring are basically not generated, the etherification selectivity is good, and high-purity o-methylphenyl alkyl ether and 2,6-dimethylphenyl alkyl ether can be easily obtained by distillation separation.

[0010] The method for producing alkyl ethers from the o-cresol post-fraction phenol oil fraction of the embodiment of the present invention comprises the following steps:

[0011] (1) adding phenol-containing coal tar to a distillation tower kettle, first removing water at normal pressure, and then distilling under reduced pressure to obtain a light oil fraction of less than 170°C, a phenol oil fraction of 170-230°C, a tricresol fraction of 230-240°C, a catechol fraction of 240-250°C, a 5-indanol fraction of 250-270°C, and a resorcinol / hydroquinone fraction of 270-300°C; wherein the phenol oil fraction of 170-230°C contains a phenol oil fraction of a post-ortho-cresol fraction of 192-195°C;

[0012] (2) adding the o-cresol post-fraction phenol oil fraction obtained in step (1) and an alkali aqueous solution into a reactor, heating and stirring, and then standing to separate layers to obtain an upper layer of dephenolized phenol oil and a water layer;

[0013] (3) adding an alkylating agent to the water layer obtained in step (2) to carry out an etherification reaction;

[0014] (4) after the etherification reaction is completed, the mixture is allowed to stand and the layers are separated to obtain a material layer and a water layer, and the material layer is washed to obtain a material layer;

[0015] (5) subjecting the material layer obtained in step (4) to vacuum distillation to obtain o-cresol phenyl alkyl ether, an intermediate fraction, 2,6-dimethylphenyl alkyl ether and a distillation still residue.

[0016] The advantages and technical effects brought by the method for producing alkyl ethers from the phenol oil fraction of the o-cresol fraction according to the embodiment of the present invention are as follows: 1. The method of the embodiment of the present invention extracts the phenol oil fraction of the o-cresol fraction with an alkaline aqueous solution to obtain an upper layer of dephenolized phenol oil and a water layer of sodium phenol salt aqueous solution, and neutral oil and other impurities in the sodium phenol salt aqueous solution can be removed after heating, and then an etherification reaction is carried out with an alkylating agent to obtain water-insoluble o-methylbenzene alkyl ether and 2,6-dimethylbenzene alkyl ether, and high-purity o-methylbenzene alkyl ether and 2,6-dimethylbenzene alkyl ether can be obtained by distillation; 2. The method of the embodiment of the present invention adopts an alkaline catalyst and an etherifying agent to react with the phenol oil fraction of the o-cresol fraction, and the boiling point of the obtained o-methylbenzene methyl ether and other substances is significantly lower than that of the dephenolized phenol oil, so that o-cresol, 2,6-dimethylphenol and the phenol oil fraction of the o-cresol fraction can be separated by layering or direct distillation. 1. The method of the embodiment of the present invention can separate phenol oil, and simultaneously separate o-methylbenzyl ether from 2,6-dimethylanisole. The phenol oil after dephenolization is sent for hydrogenation, which reduces the production cost. 2. The method of the embodiment of the present invention only produces etherified products, and basically does not produce alkyl and dealkylation reactions on the benzene ring, and has good etherification selectivity. The conversion rates of o-cresol and 2,6-dimethylphenol in the reaction can be controlled at more than 98%, so it is easy to obtain high-purity o-toluene alkyl ether and 2,6-dimethylbenzene alkyl ether through distillation separation. 3. The method of the embodiment of the present invention uses the phenol oil fraction of the o-cresol rear fraction, which is difficult to further purify o-cresol and has a low price, to replace refined o-cresol and pure 2,6-dimethylphenol to produce the corresponding alkyl etherified products, and the economic benefit is very considerable. 4. The method of the embodiment of the present invention is simple and easy to operate, has good process operability, strong usability, and significant economic benefits, and is convenient for promotion and application in industrial production.

[0017] In some embodiments, in step (1), the mass ratio of o-cresol, 2,6-dimethylphenol and m-cresol in the phenol oil fraction of the o-cresol post-fraction is: (10-98): (1-60): (0-10).

[0018] In some embodiments, in step (2), the alkaline aqueous solution includes at least one of a sodium hydroxide aqueous solution or a potassium hydroxide aqueous solution;

[0019] and / or, the molar ratio of phenolic substances to alkali in the phenol oil fraction after the o-cresol fraction is 1:1-3;

[0020] And / or, the temperature of the heating and stirring is 30 to 80° C., and the time of the heating and stirring is 0.5 to 2 h.

[0021] In some embodiments, in step (3), the alkylating agent comprises at least one of iodoalkanes, chloroalkanes, dialiphatic sulfates or dialiphatic carbonates;

[0022] And / or, the molar ratio of phenolic substances in the phenol oil fraction after o-cresol fraction to the alkylating agent is 1:0.5-5.

[0023] In some embodiments, in step (3), the temperature of the etherification reaction is 0 to 250° C., the pressure required for the etherification reaction is 0 to 10 MPa, and the time of the etherification reaction is 2 to 20 hours.

[0024] In some embodiments, in step (4), the static stratification is performed at 70 to 90° C.;

[0025] And / or, the washing treatment includes: adding sulfuric acid solution to the material layer for washing for 0.5 to 2 hours, and then washing the material layer in layers to obtain the material layer after layering.

[0026] In some embodiments, in step (5), the pressure of the vacuum distillation is -0.05 to 0.1 MPa, and the reflux ratio is 15 to 25:1.

[0027] In some embodiments, in step (5), the middle fraction includes o-methylphenyl alkyl ether and 2,6-dimethylphenyl alkyl ether;

[0028] Preferably, the intermediate fraction is combined with the material layer obtained in step (4) to undergo vacuum distillation.

[0029] In some embodiments, in step (5), the middle fraction includes o-methylbenzene alkyl ether, m-p-methylbenzene alkyl ether and 2,6-dimethylbenzene alkyl ether;

[0030] Preferably, the middle fraction is subjected to vacuum distillation to obtain o-methylbenzene alkyl ether, middle fraction 1, m-para-methylbenzene alkyl ether, middle fraction 2, 2,6-dimethylbenzene alkyl ether and still residue.

[0031] In some embodiments, the m-p-methylbenzene alkyl ether and trimethylbenzene are added to a reactor, the temperature is raised to 110-140° C., and then hydrobromic acid is added for reaction. The bromoalkane gas generated by the reaction is cooled to -10° C. to room temperature through a condenser and a cold trap and enters a bromoalkane storage tank. The reaction liquid is then cooled and allowed to stand for stratification. The hydrobromic acid aqueous solution is separated for concentration treatment. The solvent layer is washed with water. The separated material layer is first distilled to recover trimethylbenzene for reuse. Then, more than 99.5% of m-p-cresol is obtained by distillation. The by-product bromoalkane is reused as an alkylating agent.

[0032] Preferably, the trimethylbenzene includes at least one of 1,2,3-trimethylbenzene, 1,2,4-trimethylbenzene and 1,3,5-trimethylbenzene, and the amount of the trimethylbenzene is 1 to 3 times the mass of the m-p-methylbenzene alkyl ether;

[0033] and / or, the molar ratio of hydrogen bromide to m-p-methylphenyl alkyl ether in the hydrobromic acid is 1 to 3, and the concentration of the hydrobromic acid is 30 to 60%;

[0034] And / or, after adding hydrobromic acid, the reaction is maintained at 110-140° C. for 1-3 hours, and sampling and analysis are performed. The content of m-p-methylphenyl alkyl ether is ≤ 0.5%, which is acceptable. DETAILED DESCRIPTION

[0035] 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.

[0036] The method for producing alkyl ethers from the o-cresol post-fraction phenol oil fraction of the embodiment of the present invention comprises the following steps:

[0037] (1) adding phenol-containing coal tar to a distillation tower kettle, first removing water at normal pressure, and then distilling under reduced pressure to obtain a light oil fraction of less than 170°C, a phenol oil fraction of 170-230°C, a tricresol fraction of 230-240°C, a catechol fraction of 240-250°C, a 5-indanol fraction of 250-270°C, and a resorcinol / hydroquinone fraction of 270-300°C; wherein the phenol oil fraction of 170-230°C contains a phenol oil fraction of a post-ortho-cresol fraction of 192-195°C;

[0038] (2) adding the o-cresol post-fraction phenol oil fraction obtained in step (1) and an alkali aqueous solution into a reactor, heating and stirring, and then standing to separate layers to obtain an upper layer of dephenolized phenol oil and a water layer;

[0039] (3) adding an alkylating agent to the water layer obtained in step (2) to carry out an etherification reaction;

[0040] (4) after the etherification reaction is completed, the mixture is allowed to stand and the layers are separated to obtain a material layer and a water layer, and the material layer is washed to obtain a material layer;

[0041] (5) subjecting the material layer obtained in step (4) to distillation to obtain o-cresol phenyl alkyl ether, an intermediate fraction, 2,6-dimethylphenyl alkyl ether and a distillation still residue.

[0042] The method for producing alkyl ethers from the phenol oil fraction of the o-cresol fraction of the embodiment of the present invention comprises the following steps: extracting the phenol oil fraction of the o-cresol fraction with an alkaline aqueous solution to obtain an upper layer of dephenolized phenol oil and a water layer of a sodium phenol salt aqueous solution; removing impurities such as neutral oil in the sodium phenol salt aqueous solution after heating; and then performing an etherification reaction with an alkylating agent to obtain water-insoluble o-methylbenzene alkyl ether and 2,6-dimethylbenzene alkyl ether; and rectifying to obtain high-purity o-methylbenzene alkyl ether and 2,6-dimethylbenzene alkyl ether; the method adopts an alkaline catalyst and an etherifying agent to react with the phenol oil fraction of the o-cresol fraction; the boiling point of the obtained o-methylbenzene methyl ether and other substances is significantly lower than that of the dephenolized phenol oil, so that the o-cresol, 2,6-dimethylphenol and the phenol oil in the phenol oil fraction of the o-cresol fraction can be separated by stratification or direct rectification. The invention discloses a novel method for separating o-methylbenzyl ether and 2,6-dimethylanisole, and simultaneously separating o-methylbenzyl ether and 2,6-dimethylanisole, and the phenol oil after dephenolization is sent for hydrogenation, thereby reducing the production cost; the method only produces etherified products, and basically does not produce alkyl and dealkylation reactions on the benzene ring, and has good etherification selectivity. In the reaction, the conversion rates of o-cresol and 2,6-dimethylphenol can be controlled at more than 98%, so it is easy to obtain high-purity o-toluene alkyl ether and 2,6-dimethylbenzyl ether through distillation separation; the method adopts the phenol oil fraction of the o-cresol rear fraction, which is difficult to further purify o-cresol and has a low price, to replace refined o-cresol and pure 2,6-dimethylphenol to produce the corresponding alkyl etherified products, and the economic benefit is very considerable; the method is simple and easy to operate, has good process operability, strong usability, and significant economic benefits, and is convenient for popularization and application in industrial production.

[0043] In some embodiments, preferably, in the step (1), the mass ratio of o-cresol, 2,6-dimethylphenol and m-p-cresol in the phenol oil fraction of the o-cresol fraction is: (10-98): (1-60): (0-10). Further preferably, the mass ratio of o-cresol, 2,6-dimethylphenol and m-p-cresol in the phenol oil fraction of the o-cresol fraction is: (50-95): (5-50): (0-5).

[0044] In some embodiments, preferably, in step (2), the alkaline aqueous solution includes at least one of a sodium hydroxide aqueous solution or a potassium hydroxide aqueous solution;

[0045] and / or, the molar ratio of phenolic substances to alkali in the phenol oil fraction after the o-cresol fraction is 1:1-3;

[0046] And / or, the temperature of the heating and stirring is 30 to 80° C., and the time of the heating and stirring is 0.5 to 2 hours. Further preferably, the alkaline aqueous solution is a sodium hydroxide aqueous solution.

[0047] In some embodiments, in step (3), the alkylating agent comprises at least one of iodoalkanes, chloroalkanes, dialiphatic sulfates or dialiphatic carbonates;

[0048] And / or, the molar ratio of the phenolic substances in the phenol oil fraction after the o-cresol fraction to the alkylating agent is 1:0.5 to 5. More preferably, the alkylating agent is dimethyl carbonate, the molar ratio of the phenolic substances in the phenol oil fraction after the o-cresol fraction to the alkylating agent is 1:1 to 3, and the dimethyl carbonate is added to the reactor in a dropwise manner, and the temperature during the dropwise addition is not higher than 60°C.

[0049] In the embodiment of the present invention, the amount of the alkylating agent is preferably selected. If the amount of the alkylating agent is too low, the phenolic material cannot be completely etherified, and o-cresol, 2,6-dimethylphenol, etc. will still exist in the product. The unreacted o-cresol, etc. will dissolve in the ether. During distillation, since the boiling point of o-cresol is 191° C., which is 9-10° C. higher than 2,6-dimethylanisole, the effect on the distillation of o-methylbenzyl ether and 2,6-dimethylanisole in the high-efficiency distillation tower is limited, but the production cost will be increased. If the amount of the alkylating agent is too high, the reaction yield is guaranteed, but the excess dimethyl carbonate will dissolve in the etherified product generated by the reaction, and a small amount of dimethyl carbonate dissolved in water will gradually hydrolyze in water, resulting in a waste of the alkylating agent and adding a burden to the treatment of wastewater. Before distillation, dimethyl carbonate is first recovered at normal pressure, and then the etherified product is obtained by vacuum distillation to recover most of the dimethyl carbonate. Excessive use of the alkylating agent has little effect on the product quality under normal temperature conditions, but it will affect the product quality under high temperature. The alkylating agent is further preferably dimethyl carbonate with lower toxicity, which improves the safety of production operation, reduces poisoning behavior, and is beneficial to the health of operators.

[0050] In some embodiments, preferably, in step (3), the temperature of the etherification reaction is 0-250°C, the pressure required for the etherification reaction is 0-10 MPa, and the time of the etherification reaction is 2-20 hours. Further preferably, the temperature of the etherification reaction is 40-150°C, and the pressure required for the etherification reaction is 0-1 MPa.

[0051] In some embodiments, preferably, in the step (4), the static stratification is performed at 70 to 90° C.;

[0052] And / or, the washing treatment includes: adding sulfuric acid solution to the material layer for washing for 0.5 to 2 hours, then washing the material layer with water in layers, and completely removing the washing water in layers to obtain the material layer.

[0053] In some embodiments, preferably, in the step (5), the pressure of the distillation treatment is -0.05 to 0.1 MPa, and the reflux ratio is 20 to 25:1.

[0054] In some embodiments, preferably, in the step (5), the middle distillate comprises o-methylbenzene alkyl ether and 2,6-dimethylbenzene alkyl ether;

[0055] Preferably, the intermediate fraction is combined with the material layer obtained in step (4) to undergo vacuum distillation.

[0056] In some embodiments, preferably, in the step (5), the middle fraction comprises o-methylbenzene alkyl ether, m-p-methylbenzene alkyl ether and 2,6-dimethylbenzene alkyl ether;

[0057] Preferably, the middle fraction is subjected to vacuum distillation to obtain o-methylbenzene alkyl ether, middle fraction 1, m-para-methylbenzene alkyl ether, middle fraction 2, 2,6-dimethylbenzene alkyl ether and still residue.

[0058] In some embodiments, preferably, the m-p-methylbenzene alkyl ether and trimethylbenzene are added to a reactor, the temperature is raised to 110-140°C, and then hydrobromic acid is added for reaction. The brominated alkane gas generated by the reaction is cooled to -10°C to room temperature through a condenser and a cold trap and enters a brominated alkane storage tank. The reaction solution is then cooled and allowed to stand for stratification, the hydrobromic acid aqueous solution is separated for concentration treatment, the solvent layer is washed with water, the separated material layer is first distilled to recover trimethylbenzene for reuse, and then distilled to obtain more than 99.5% of m-p-cresol, and the by-product brominated alkane is reused as an alkylating agent.

[0059] Further preferably, the trimethylbenzene includes at least one of 1,2,3-trimethylbenzene, 1,2,4-trimethylbenzene and 1,3,5-trimethylbenzene, and the amount of the trimethylbenzene is 1 to 3 times the mass of the m-p-methylbenzene alkyl ether;

[0060] and / or, the molar ratio of the hydrogen bromide to the m-p-methylphenyl alkyl ether is 1 to 3, and the concentration of the hydrobromic acid is 30 to 60%;

[0061] And / or, after adding hydrobromic acid, the reaction is maintained at 110-140° C. for 1-3 hours, and sampling and analysis are performed. The content of m-p-methylphenyl alkyl ether is ≤ 0.5%, which is acceptable.

[0062] In the embodiment of the present invention, hydrobromic acid is reacted with m-p-methylbenzene alkyl ether to generate high-purity m-p-cresol, which can be used to produce high-grade photoresist and flame-retardant plasticizer tricresyl phosphate for aerospace, and has great economic benefits. In addition, hydrobromic acid can also be reacted with o-methylbenzene alkyl ether or 2,6-dimethylbenzene alkyl ether to generate high-purity o-cresol and high-purity 2,6-dimethylphenol, which are applied in industrial production.

[0063] The technical solution of the present application is described in detail below in conjunction with specific embodiments.

[0064] Example 1

[0065] (1) 800,000 parts of phenol-containing coal tar obtained by pyrolysis of coal of an energy enterprise in Xinjiang Uygur Autonomous Region (all parts are measured by weight in the embodiments) are added to a distillation tower kettle, 1381 parts of water are first removed under normal pressure, and then distilled under reduced pressure (10 mmHg column) to obtain 10,805 parts of light oil fraction <170°C, 110,301 parts of phenol oil fraction at 170-230°C (including 3734 parts of phenol oil fraction of post-ortho-cresol fraction at 192-195°C), 16,445 parts of tricresol fraction at 230-240°C, 14,643 parts of catechol fraction at 240-250°C, 46,162 parts of 5-indanol fraction at 250-270°C, and 74,405 parts of resorcinol / hydroquinone fraction at 270-300°C. 521,860 parts of residual coal tar in the distillation kettle are sent to a hydrogenation workshop to produce gasoline and diesel.

[0066] 3734 samples of phenol oil fraction containing 192-195°C o-cresol fraction were sampled and analyzed, with a phenol content of 50.6%, including: o-cresol 69.9%, 2,6-dimethylphenol 28.3%, and m-cresol 1.1%, calculated in percentage by mass.

[0067] (2) Add 3734 parts of the phenol oil fraction of the o-cresol fraction obtained in step (1) and 2500 parts of a 31.2% aqueous solution of sodium hydroxide (the molar ratio of the phenolic substances in the phenol oil fraction of the o-cresol fraction to sodium hydroxide is 1:1.152) into an enameled reactor, start stirring, raise the temperature to 70°C and stir for 1 hour, let stand for 1 hour to separate the layers, and obtain 4392 parts of an aqueous solution, from which 1834 parts of dephenolized phenol oil are separated.

[0068] (3) 1267 parts of dimethyl sulfate (the molar ratio of phenolic substances to dimethyl sulfate is 1:0.6) is added dropwise to the aqueous solution obtained in step (2), the dropping temperature is controlled not to exceed 60°C, the dropping time is about 3 hours, after the dropping is completed, the reaction is kept warm under slightly boiling conditions (100°C) for 8 hours, and sampling and analysis are performed, o-cresol 0.22%, the temperature is lowered to 80°C, and the mixture is allowed to stand for stratification, the lower water layer is separated, and the water layer is sent to a wastewater station to recover sodium sulfate, etc., 50 parts of water are added to the material layer, and 20 parts of sulfuric acid are added dropwise while stirring to wash for 1 hour to remove impurities, the material layer is separated, and the material layer is washed once with 50 parts of water, and the water is separated, and the material layer is subjected to the following treatment.

[0069] (4) The above material layer was added to a distillation kettle and subjected to vacuum distillation (-0.085 MPa) at a reflux ratio of 15 to 25:1. The total reflux was performed for 2 hours every 6 hours of distillation. 9.2 parts of the front fraction, 1472.2 parts of 99.71% o-methylbenzyl ether (1467.9 parts of o-methylbenzyl ether, 0.3 parts of 2,6-dimethylanisole, and 2.4 parts of m-p-methylanisole) and 40.1 parts of the middle fraction were collected. parts (4.6 parts of o-methylbenzyl ether, 16.9 parts of m-para-methylanisole, 18.2 parts of 2,6-dimethylanisole), 536.4 parts of 99.58% 2,6-dimethylanisole (0.2 parts of o-methylbenzyl ether, 2.1 parts of m-para-methylanisole, 534.1 parts of 2,6-dimethylanisole), and 38.6 parts of the distillation still residue (including 37.4 parts of 2,6-dimethylanisole).

[0070] The distillation still residue is used to distill 99% of 2,6-dimethylanisole.

[0071] (5) After the middle fractions were combined in batches, 802 parts (92 parts of o-methylbenzyl ether, 338 parts of m-para-methylanisole, and 364 parts of 2,6-dimethylanisole) were added to a high-efficiency rectification kettle and subjected to vacuum distillation to obtain 56.3 parts of 99.11% o-methylbenzyl ether (55.8 parts of o-methylbenzyl ether), 122.6 parts of middle fraction 1 (35.2 parts of o-methylbenzyl ether, 87.4 parts of m-para-methylanisole), and 177.5 parts of 99.55% m-para-methylanisole ( 0.5 parts of o-methylbenzyl ether, 176.7 parts of m-para-methylanisole, 0.3 parts of 2,6-dimethylanisole), 154.8 parts of middle distillate 2 (70.5 parts of m-para-methylanisole, 84.3 parts of 2,6-dimethylanisole), 239.3 parts of 99.41% 2,6-dimethylanisole (1.4 parts of m-para-methylanisole, 237.9 parts of 2,6-dimethylanisole), and 41.0 parts of still residue (39.6 parts of 2,6-dimethylanisole).

[0072] (6) 122.6 parts of middle distillate 1 (35.2 parts of o-methylbenzyl ether and 87.4 parts of m-p-methylanisole) and 150 parts of mixed trimethylbenzene were added to the reactor, the temperature was raised to 120-130° C., 47% hydrobromic acid was added dropwise for reaction, the addition time was 3 hours, the methyl bromide gas generated by the reaction was cooled to −10° C. by a condenser and two cold traps and entered into a bromoalkane storage tank (−15° C.), the temperature was kept for 2.5 hours after the addition was completed, and sampling and analysis were performed, the m-methylanisole content was 0.08%, the reaction was completed, and the collection of bromoalkane was stopped, a total of 346 parts of 47% hydrobromic acid was added dropwise, 93.2 parts of methyl bromide were collected, and the yield was 97.6%; then the reaction solution was cooled slightly and the hydrobromic acid was separated Acid aqueous solution, the solvent layer is washed once with 35 parts of water, the layers are separated, and the water layers are combined to obtain 296.9 parts of 27.0% hydrobromic acid solution (sent to other sections for concentration and recovery of 47% hydrobromic acid), 147.1 parts of trimethylbenzene are recovered in the material layer rectification kettle and reused, and then the material is added to the kettle of the rectification tower added with 50 parts of high boiling point solvent and distilled under reduced pressure to obtain 27.9 parts of 99.2% o-cresol (0.3ppm sulfide, 0.2ppm pyridine base), 11.9 parts of intermediate fractions (3.1 parts of o-cresol, 8.8 parts of m-cresol), and 67.8 parts of 99.85% high-purity m-cresol (0.2ppm sulfide, 0.2ppm pyridine base).

[0073] (7) 177.5 parts of m-p-methylanisole (0.5 parts of o-methylbenzyl ether, 176.7 parts of m-p-methylanisole, and 0.3 parts of 2,6-dimethylanisole) and 200 parts of mixed trimethylbenzene were added to the reaction kettle, the temperature was raised to 130-135° C., 47% hydrobromic acid was added dropwise for 3 hours, and the methyl bromide gas generated by the reaction was cooled to -10° C. by a condenser and a second cold trap and then entered into a bromoalkane storage tank (-15° C.). After the addition was completed, the mixture was kept warm for 2 hours and then sampled and analyzed. The m-methylanisole content was 0.16%. After the reaction was completed, the collection of bromoalkane was stopped. A total of 500 parts of 47% hydrobromic acid was added dropwise, and 135.5 parts of methyl bromide were collected. , yield 98%; then the reaction solution is cooled slightly to separate the hydrobromic acid aqueous solution, the solvent layer is washed once with 40 parts of water, the layers are separated, the water layers are combined, and 416.4 parts of 27.4% hydrobromic acid solution are obtained (sent to other sections for concentration and recovery of 47% hydrobromic acid), 196.3 parts of trimethylbenzene are recovered in the material layer distillation kettle and reused, and then the material is added to the kettle of the distillation tower with 50 parts of high boiling point solvent and vacuum distilled to obtain 6.1 parts of the fore fraction (85.2% of m-cresol), 149.7 parts of high-purity m-cresol (99.95% of m-cresol, 0.05% of 2,6-dimethylphenol, 0.3ppm of sulfide, and 0.4ppm of pyridine base).

[0074] The middle fraction 2 can be treated in the same way as the middle fraction 1 to produce low-impurity high-purity m-p-cresol and 2,6-xylenol through demethylation.

[0075] The embodiment of the present invention obtains: 99.71% and 99.11% of o-methylbenzyl ether, 99.58% and 99.41% of 2,6-dimethylanisole, 99.2% of o-cresol, and 99.85% and 99.95% of m-p-cresol.

[0076] Example 2

[0077] (1) 1,600,000 parts (in parts by weight in the examples) of phenol-containing coal tar obtained by coal gasification of an energy enterprise in Xinjiang Uygur Autonomous Region were added to the bottom of a distillation tower, 4,926 parts of water were first removed at 50 KPa, and then the bottom of the tower was slightly cooled and gradually transitioned to 5 KPa for distillation to obtain 28,731 parts of a light oil fraction of <170°C, 264,866 parts of a phenol oil fraction of 170-230°C (containing 19 10080 parts of phenol oil fraction of the post-fraction of o-cresol at 2-196°C), 30881 parts of tricresol fraction at 230-240°C, 27056 parts of catechol fraction at 240-250°C, 84323 parts of 5-indanol fraction at 250-270°C, 134649 parts of resorcinol / hydroquinone fraction at 270-300°C, and 1008565 parts of residual coal tar in the distillation kettle were sent to the hydrogenation workshop to produce gasoline and diesel.

[0078] 10080 samples of phenol oil fraction containing 192-196°C o-cresol fraction were sampled and analyzed, with a phenol content of 46.7%, including: o-cresol 54.9%, 2,6-dimethylphenol 35.6%, and m-cresol 8.9%, calculated in percentage by mass.

[0079] (2) Into an enameled reactor, 10,080 parts of the o-cresol post-fraction phenol oil fraction obtained in step (1) and 6,384 parts of a 30.8% aqueous sodium hydroxide solution (the molar ratio of the phenolic substances in the o-cresol post-fraction phenol oil fraction to sodium hydroxide is 1:1.177) were added, and stirring was started. The temperature was raised to 70° C. and stirred for 1 hour. The mixture was allowed to stand for 1 hour to separate the layers, and 11,028 parts of an aqueous solution were obtained, from which 5,423.6 parts of dephenolized phenol oil were separated.

[0080] (3) Add 1100 parts of dimethyl carbonate (the molar ratio of phenolic substances to dimethyl carbonate is 1:0.59) dropwise to 5514 parts of the aqueous solution obtained in step (2), control the dropping temperature not to exceed 90°C, and the dropping time is about 3 hours. After the dropping is completed, keep the reaction at 100°C for 8 hours and take samples for analysis. The temperature is reduced to 80°C and allowed to stand for stratification. The lower water layer is separated and the water layer is sent to a wastewater station to recover sodium sulfate, etc. The material layer is added with 100 parts of water and stirred, and 20 parts of sulfuric acid is added dropwise to wash for 1 hour to remove impurities. The material layer is separated and washed once with 100 parts of water. The water is separated and the material layer is subjected to the following treatment.

[0081] (4) The above material layer was added to a distillation kettle and distilled under reduced pressure (-0.085 MPa) at a reflux ratio of 20 to 25:1. The total reflux was performed for 2 hours for every 6 hours of distillation. 21.8 parts of the front fraction, 1319.6 parts of 99.59% o-methylbenzyl ether (1314.2 parts of o-methylbenzyl ether and 5.0 parts of m-methylanisole), 426.7 parts of the middle fraction (114.8 parts of o-methylbenzyl ether, 225.3 parts of m-methylanisole and 85.7 parts of 2,6-dimethylanisole), 782.8 parts of 99.71% 2,6-dimethylanisole (1.2 parts of m-methylanisole, 780.5 parts of 2,6-dimethylanisole and 1.1 parts of others) were collected. 57.4 parts of the distillation kettle residue were obtained (including 46.3 parts of 2,6-dimethylanisole and 11.1 parts of others).

[0082] The distillation still residue is used to distill 99% of 2,6-dimethylanisole.

[0083] (5) 426.7 parts of the middle fraction were added to a high-efficiency distillation kettle (50 parts of a high-boiling-point solvent were added to the kettle), and subjected to vacuum distillation to obtain 90 parts of 99.78% o-methylbenzyl ether (89.8 parts of o-methylbenzyl ether and 0.2 parts of m-para-methylanisole), 51.9 parts of middle fraction 1 (23.7 parts of o-methylbenzyl ether and 28.1 parts of m-para-methylanisole), 177.3 parts of 99.27% ​​m-para-methylanisole (0.5 parts of o-methylbenzyl ether, 176 parts of m-para-methylanisole and 0.6 parts of 2,6-dimethylanisole), 45.6 parts of middle fraction 2 (19.1 parts of m-para-methylanisole and 26.4 parts of 2,6-dimethylanisole), and 58.8 parts of 99.32% 2,6-dimethylanisole (0.3 parts of m-para-methylanisole and 58.4 parts of 2,6-dimethylanisole).

[0084] The middle fraction 1 and the middle fraction 2 can be used to separate o-methylbenzyl ether, m-methylbenzyl ether, p-methylbenzyl ether and 2,6-dimethylbenzyl ether by tert-butylation method; or they can be returned to the etherified mixture to be distilled after washing in (3).

[0085] (6) 177.3 parts of m-p-methylanisole (0.5 parts of o-methylbenzyl ether, 176 parts of m-p-methylanisole, and 0.6 parts of 2,6-dimethylanisole) and 200 parts of mixed trimethylbenzene were added to the reaction kettle, the temperature was raised to 120-130° C., 47% hydrobromic acid was added dropwise for 3 hours, and the methyl bromide gas generated by the reaction was cooled to -10° C. by a condenser and a second cold trap and then entered into a bromoalkane storage tank (-15° C.). After the addition was completed, the temperature was kept for 2.5 hours and a sample was taken for analysis. The m-methylanisole content was 0.11%. After the reaction was completed, the collection of bromoalkane was stopped. A total of 500 parts of 47% hydrobromic acid were added dropwise and the bromoalkane was collected. 133.8 parts of methyl bromide, yield 96.8%; then the reaction solution is cooled slightly to separate the hydrobromic acid aqueous solution, the solvent layer is washed once with 50 parts of water, the layers are separated, the water layers are combined to obtain 427.8 parts of 27.1% hydrobromic acid solution (sent to other sections for concentration and recovery of 47% hydrobromic acid), 196.3 parts of trimethylbenzene are recovered in the material layer distillation kettle and reused, and then the material is added to the kettle of the distillation tower added with 50 parts of high boiling point solvent and distilled under reduced pressure to obtain 6.6 parts of the fore fraction (78.8% of m-cresol) and 149.1 parts of high-purity m-cresol (99.93% of m-cresol and 0.07% of 2,6-dimethylphenol).

[0086] The embodiment of the present invention produces: 99.59% and 99.78% of o-methylbenzyl ether and 99.71% and 99.32% of 2,6-dimethylanisole; 99.93% of high-purity m-p-cresol (2,6-dimethylphenol ≤ 0.1%), which are used to produce m-cresol-formaldehyde resin for high-grade photoresist and non-toxic flame-retardant plasticizer tricresyl phosphate for aerospace.

[0087] Example 3

[0088] (1) 1,600,000 parts (in parts by weight in this embodiment) of phenol-containing coal tar obtained by coal gasification of an energy enterprise in Xinjiang Uygur Autonomous Region were added to the bottom of a distillation tower, 4,926 parts of water were first removed at 50 KPa, and then the bottom of the tower was slightly cooled and gradually transferred to 5 KPa for distillation to obtain 28,731 parts of light oil fraction <170°C, 264,866 parts of phenol oil fraction (containing 19 10080 parts of phenol oil fraction of the post-fraction of o-cresol at 2-196°C), 30881 parts of tricresol fraction at 230-240°C, 27056 parts of catechol fraction at 240-250°C, 84323 parts of 5-indanol fraction at 250-270°C, 134649 parts of resorcinol / hydroquinone fraction at 270-300°C, and 1008565 parts of residual coal tar in the distillation kettle were sent to the hydrogenation workshop to produce gasoline and diesel.

[0089] 10080 samples of phenol oil fraction containing 192-196°C o-cresol fraction were sampled and analyzed, with a phenol content of 46.7%, including: o-cresol 54.9%, 2,6-dimethylphenol 35.6%, and m-cresol 8.9%, calculated in percentage by mass.

[0090] (2) Into an enameled reactor, 10,080 parts of the o-cresol post-fraction phenol oil fraction obtained in step (1) and 6,384 parts of a 30.8% aqueous sodium hydroxide solution (the molar ratio of the phenolic substances in the o-cresol post-fraction phenol oil fraction to sodium hydroxide is 1:1.177) were added, and stirring was started. The temperature was raised to 70° C. and stirred for 1 hour. The mixture was allowed to stand for 1 hour to separate the layers, and 11,028 parts of an aqueous solution were obtained, from which 5,423.6 parts of dephenolized phenol oil were separated.

[0091] (3) Add 5514 parts of the aqueous solution obtained in step (2) into a high-pressure reactor and 4565 parts of a 20.5% sodium hydroxide aqueous solution, start stirring, and pressurize 2380 parts of methyl bromide (the molar ratio of phenolic substances to methyl bromide is 1:1.11). The container is sealed, the temperature is raised to 90-95°C, and the reaction is kept warm for 5 hours. Sample analysis shows that 0.13% of o-cresol is qualified. The pressure is released and deep cold recovery is obtained to obtain 156.6 parts of methyl bromide, which is applied to the next batch of etherification reaction. The reaction solution is cooled to 60°C and allowed to stand for stratification. 6501.7 parts of the lower water layer (which contains 2404.5 parts of sodium bromide, accounting for 36.98%) is separated, and the water layer is sent to recover bromine or hydrobromic acid (or sodium bromide); 100 parts of water are added to the etherified layer of the reaction product, and 50 parts of sulfuric acid are added dropwise while stirring for 1 hour to remove alkaline substances such as aniline, and the layers are separated and washed with 100 parts of water. The water is separated as much as possible, and the material layer is subjected to the following treatment.

[0092] (4) The above material layer was added to a distillation kettle and distilled under reduced pressure (-0.085 MPa) at a reflux ratio of 20 to 25:1. The total reflux was performed for 2 hours for every 4 hours of distillation. 18.9 parts of the front fraction, 1336.9 parts of 99.74% o-methylbenzyl ether (1333.5 parts of o-methylbenzyl ether and 3.1 parts of m-para-methylanisole), 406.9 parts of the middle fraction (103.2 parts of o-methylbenzyl ether, 230.8 parts of m-para-methylanisole and 72.8 parts of 2,6-dimethylanisole), 806.5 parts of 99.75% 2,6-dimethylanisole (1.1 parts of m-para-methylanisole, 804.5 parts of 2,6-dimethylanisole and 0.9 parts of others) were collected. 57.9 parts of the distillation kettle residue (including 45.7 parts of 2,6-dimethylanisole and 12.2 parts of others) were obtained.

[0093] The distillation still residue is used to distill 99% of 2,6-dimethylanisole.

[0094] (5) 406.9 parts of the middle fraction were added to a high-efficiency distillation kettle (50 parts of a high-boiling point solvent was added to the kettle), and distilled under reduced pressure to obtain 86 parts of 99.51% o-methylbenzyl ether (85.6 parts of o-methylbenzyl ether and 0.3 parts of m-para-methylanisole), 42.1 parts of middle fraction 1 (16.6 parts of o-methylbenzyl ether and 25.5 parts of m-para-methylanisole), 189 parts of 99.20% m-para-methylanisole (0.5 parts of o-methylbenzyl ether, 187.5 parts of m-para-methylanisole and 0.7 parts of 2,6-dimethylanisole), 38.3 parts of middle fraction 2 (15.6 parts of m-para-methylanisole and 12.6 parts of 2,6-dimethylanisole), and 59.3 parts of 99.33% 2,6-dimethylanisole (0.2 parts of m-para-methylanisole and 58.9 parts of 2,6-dimethylanisole).

[0095] The middle fraction 1 and the middle fraction 2 can be used to separate o-methylbenzyl ether, m-methylbenzyl ether, p-methylbenzyl ether and 2,6-dimethylbenzyl ether by tert-butylation method; or they can be returned to the etherified mixture to be distilled after washing in (3).

[0096] (6) 189 parts of m-p-methylanisole (0.5 parts of o-methylbenzyl ether, 187.5 parts of m-p-methylanisole, and 0.7 parts of 2,6-dimethylanisole) and 200 parts of mixed trimethylbenzene were added to the reactor, the temperature was raised to 130°C, 47% hydrobromic acid was added dropwise for reaction, the addition time was 2.5 hours, the methyl bromide gas generated by the reaction was cooled to -10°C by a condenser and a second cold trap and entered into a bromoalkane storage tank (-15°C), after the addition was completed and the temperature was kept for 2 hours, a sample was taken for analysis, and the m-methylanisole content was 0.08%. After the reaction was completed, the collection of bromoalkane was stopped, and a total of 550 parts of 47% hydrobromic acid (molar ratio of hydrogen bromide to m-p-methylanisole was 2.05:1) was added dropwise, and 142. 7 parts, with a yield of 97%; then the reaction solution is cooled slightly to separate the hydrobromic acid aqueous solution, the solvent layer is washed once with 50 parts of water, the layers are separated, and the water layers are combined to obtain 469.5 parts of 27.3% hydrobromic acid solution (sent to other sections for concentration and recovery of 47% hydrobromic acid), 195.8 parts of trimethylbenzene are recovered in the material layer distillation kettle and applied to the next dealkylation reaction (to generate m-cresol), and then the material is added to the kettle of a distillation tower added with 50 parts of a high boiling point solvent and distilled under reduced pressure (-0.085Mpa, reflux ratio 10-15) to obtain 2.5 parts of the fore fraction (64% of m-cresol) and 164.5 parts of high-purity m-cresol (99.88% of m-cresol and 0.06% of 2,6-xylenol).

[0097] The embodiment of the present invention produces: 99.74% and 99.51% of o-methyl anisole, 99.33% and 99.75% of 2,6-dimethyl anisole; 99.88% of high-purity m-p-cresol (2,6-dimethylphenol ≤ 0.1%), which are used to produce m-cresol-formaldehyde resin for high-grade photoresist and non-toxic flame-retardant plasticizer tricresyl phosphate for aerospace.

[0098] 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.

[0099] Although the above embodiments have been shown and described, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations on the present invention. Changes, modifications, substitutions and variations of the above embodiments by those of ordinary skill in the art are all within the scope of protection of the present invention.

Claims

1. A method for producing alkyl ethers from o-cresol post-fraction phenol oil fraction, characterized in that: The steps include: (1) adding phenol-containing coal tar to a distillation tower kettle, first removing water at normal pressure, and then distilling under reduced pressure to obtain a light oil fraction of less than 170°C, a phenol oil fraction of 170-230°C, a tricresol fraction of 230-240°C, a catechol fraction of 240-250°C, a 5-indanol fraction of 250-270°C, and a resorcinol / hydroquinone fraction of 270-300°C; wherein the phenol oil fraction of 170-230°C contains a phenol oil fraction of a post-ortho-cresol fraction of 192-195°C; (2) adding the o-cresol post-fraction phenol oil fraction obtained in step (1) and an alkali aqueous solution into a reactor, heating and stirring, and then standing to separate layers to obtain an upper layer of dephenolized phenol oil and a water layer; (3) adding an alkylating agent to the water layer obtained in step (2) to carry out an etherification reaction; (4) after the etherification reaction is completed, the mixture is allowed to stand and the layers are separated to obtain a material layer and a water layer, and the material layer is washed to obtain a material layer; (5) subjecting the material layer obtained in step (4) to vacuum distillation to obtain o-methylbenzene alkyl ether, an intermediate fraction, 2,6-dimethylbenzene alkyl ether and a distillation still residue.

2. The method for producing alkyl ethers from o-cresol post-fraction phenol oil fraction according to claim 1, characterized in that: In the step (1), the mass ratio of o-cresol, 2,6-dimethylphenol and m-p-cresol in the o-cresol post-fraction phenol oil fraction is: (10-98): (1-60): (0-10).

3. The method for producing alkyl ethers from o-cresol post-fraction phenol oil fraction according to claim 1, characterized in that: In the step (2), the alkaline aqueous solution includes at least one of a sodium hydroxide aqueous solution or a potassium hydroxide aqueous solution; and / or, the molar ratio of phenolic substances to alkali in the phenol oil fraction after the o-cresol fraction is 1:1-3; And / or, the temperature of the heating and stirring is 30 to 80° C., and the time of the heating and stirring is 0.5 to 2 h.

4. The method for producing alkyl ethers from o-cresol post-fraction phenol oil fraction according to claim 1, characterized in that: In the step (3), the alkylating agent comprises at least one of iodoalkanes, chloroalkanes, di-fatty sulfates or di-fatty carbonates; And / or, the molar ratio of phenolic substances in the phenol oil fraction after o-cresol fraction to the alkylating agent is 1:0.5-5.

5. The method for producing alkyl ethers from o-cresol post-fraction phenol oil fraction according to claim 1 or 4, characterized in that: In the step (3), the temperature of the etherification reaction is 0 to 250° C., the pressure required for the etherification reaction is 0 to 10 MPa, and the time of the etherification reaction is 2 to 20 hours.

6. The method for producing alkyl ethers from o-cresol post-fraction phenol oil fraction according to claim 1, characterized in that: In the step (4), the static stratification is carried out at 70 to 90° C.; And / or, the washing treatment includes: adding sulfuric acid solution to the material layer for washing for 0.5 to 2 hours, and then washing the material layer in layers to obtain the material layer after layering.

7. The method for producing alkyl ethers from o-cresol post-fraction phenol oil fraction according to claim 1, characterized in that: In the step (5), the pressure of the vacuum distillation is -0.05 to -0.1 MPa, and the reflux ratio is 15 to 25:

1.

8. The method for producing alkyl ethers from o-cresol post-fraction phenol oil fraction according to claim 1, characterized in that: In the step (5), the middle fraction comprises o-methylbenzene alkyl ether and 2,6-dimethylbenzene alkyl ether; Preferably, the intermediate fraction is combined with the material layer obtained in step (4) to undergo vacuum distillation.

9. The method for producing alkyl ethers from o-cresol post-fraction phenol oil fraction according to claim 1, characterized in that: In the step (5), the middle fraction comprises o-methylbenzene alkyl ether, m-p-methylbenzene alkyl ether and 2,6-dimethylbenzene alkyl ether; Preferably, the middle fraction is subjected to vacuum distillation to obtain o-methylbenzene alkyl ether, middle fraction 1, m-para-methylbenzene alkyl ether, middle fraction 2, 2,6-dimethylbenzene alkyl ether and still residue.

10. The method for producing alkyl ethers from o-cresol post-fraction phenol oil fraction according to claim 9, characterized in that: The m-p-methylbenzene alkyl ether and trimethylbenzene are added to a reactor, the temperature is raised to 110-140° C., and then hydrobromic acid is added for reaction, the bromoalkane gas generated by the reaction is cooled to -10° C. to room temperature through a condenser and a cold trap and enters a bromoalkane storage tank, and then the reaction liquid is cooled and allowed to stand for stratification, the hydrobromic acid aqueous solution is separated for concentration treatment, the solvent layer is washed with water, the separated material layer is first rectified to recover trimethylbenzene for reuse, and then rectified to obtain more than 99.5% of m-p-cresol, and the by-product bromoalkane is reused as an alkylating agent; Preferably, the trimethylbenzene includes at least one of 1,2,3-trimethylbenzene, 1,2,4-trimethylbenzene and 1,3,5-trimethylbenzene; the amount of the trimethylbenzene is 1 to 3 times the mass of the m-p-methylbenzene alkyl ether; and / or, the molar ratio of hydrogen bromide to m-p-methylphenyl alkyl ether in the hydrobromic acid is 1 to 3, and the concentration of the hydrobromic acid is 30 to 60%; And / or, after adding hydrobromic acid, the reaction is maintained at 110-140° C. for 1-3 hours, and sampling and analysis are performed. The content of m-p-methylphenyl alkyl ether is ≤ 0.5%, which is acceptable.