Process for the isolation of 2-alkylanthraquinones, 2-alkylanthraquinone products produced by the process and their use

Abstract

The present application relates to the technical field of separation, and particularly to a method for separating 2-alkylanthraquinone, a 2-alkylanthraquinone product and application thereof. The method comprises: sequentially performing osmotic vaporization, crystallization and molten water washing on 2-alkylanthra oxidation reaction liquid to obtain a 2-alkylanthraquinone product with a purity of greater than or equal to 99 wt%. The method provided by the present application uses 2-alkylanthra oxidation reaction liquid with complex components as raw material, and through the coupling of osmotic vaporization-crystallization-molten water washing, a 2-alkylanthraquinone product with high purity is obtained. Meanwhile, the 2-alkylanthraquinone product obtained by the method has good single impurity indexes, and can be used as a standard product of 2-alkylanthraquinone.

Description

Technical Field

[0001] This invention relates to the field of separation technology, specifically to a method for separating 2-alkylanthraquinone, a 2-alkylanthraquinone product obtained by the method, and its applications. Background Technology

[0002] Currently, the production of commercial hydrogen peroxide both domestically and internationally mainly relies on the anthraquinone process, which accounts for 95% of global production and 98% of domestic production. The phthalic anhydride process is the primary method for producing 2-alkylanthraquinone, the main component of the anthraquinone working solution, but this process suffers from serious pollution problems. Producing 1 ton of 2-ethylanthraquinone requires 1.76 tons of anhydrous AlCl3 and 4.2 tons of fuming sulfuric acid, both of which are difficult to recover. Therefore, from the perspective of environmental protection and clean production, developing a green production process for 2-alkylanthraquinone is extremely important.

[0003] The process of preparing 2-alkylanthraquinone by alkylating anthracene to 2-alkylanthraquinone is considered a green production technology with broad application prospects due to its advantages such as simple process flow, wide availability of raw materials, and low environmental pollution. 2-alkylanthraquinone, as a "carrier" for recycling in the hydrogen peroxide production process, requires high purity, especially the removal of trace impurities that affect hydrogenation and oxidation efficiency and long-term cycle stability. For the oxidation reaction system, firstly, due to the limitations of the catalytic activity, selectivity, and separation difficulties of the preceding alkylation reaction, the purity of the 2-alkylanthraquinone feedstock is often low, introducing some difficult-to-remove and widely distributed impurities such as heteroatoms, pigments, organic acids, and soluble salts into the reaction system; secondly, the addition of reaction solvents and oxidation catalysts, as well as their poor stability, also increase the separation difficulty; simultaneously, the oxidation reaction still presents problems with catalytic activity and side reactions. Therefore, the separation and purification of high-purity 2-alkylanthraquinone in such a complex system requires the development of specialized and efficient separation technologies.

[0004] CN111825544A, CN111825540A and US3953482 all disclose oxidation methods for preparing the corresponding anthraquinones from anthracene or 2-alkylanthracene, but none of them provide a method for purifying 2-alkylanthraquinones from the oxidation reaction products.

[0005] CN107162889A discloses a method for preparing and purifying 2-tert-pentylanthraquinone based on 2-(4'-tert-pentylbenzoyl)benzoic acid (ABB acid), but the separation method is limited to this reaction system; CN106365970A discloses a method for separating and purifying 2-tert-pentylanthraquinone from a mixture of ABB acid and 2-tert-pentylanthraquinone, with a purity >95wt%; CN110511130A discloses a method for purifying 2-tert-pentylanthraquinone from a mixture of 2-sec-pentylanthraquinone and 2-tert-pentylanthraquinone, obtaining 2-tert-pentylanthraquinone with a purity ≥99wt%. In other words, the prior art only discloses methods for separating 2-tert-pentylanthraquinone from binary components containing 2-tert-pentylanthraquinone, and does not involve methods for directly post-processing from the oxidation reaction solution to obtain high-purity 2-alkylanthraquinone. Summary of the Invention

[0006] The purpose of this invention is to overcome the problems of existing methods for separating 2-alkylanthraquinone, such as the inability to directly separate 2-alkylanthraquinone from the 2-alkylanthraquinone oxidation reaction solution, low purity of 2-alkylanthraquinone, and complex process flow. This invention provides a new method for separating 2-alkylanthraquinone, as well as a 2-alkylanthraquinone product obtained by this method and its application. This method efficiently removes impurities from the 2-alkylanthraquinone oxidation reaction solution to obtain a 2-alkylanthraquinone product with a purity ≥99wt%.

[0007] To achieve the above objectives, the first aspect of the present invention provides a method for separating 2-alkylanthraquinone, the method comprising: sequentially pervaporating, crystallizing and washing with molten water on a 2-alkylanthraquinone oxidation reaction solution to obtain a 2-alkylanthraquinone product with a purity ≥99wt%.

[0008] Preferably, the method includes the following steps:

[0009] (1) The 2-alkylanthracene oxidation reaction solution is subjected to pervaporation to obtain water and a solid-liquid mixture with a water content ≤1wt%; the solid-liquid mixture is subjected to a first filtration to obtain a solid mixture rich in hydrophilic impurities, and a crystalline liquid containing 2-alkylanthracene, 2-alkylanthraquinone and lipophilic impurities;

[0010] (2) The crystallization solution is crystallized to obtain crude 2-alkylanthraquinone crystals;

[0011] (3) The crude 2-alkylanthraquinone crystals are subjected to melt washing, cooling and solid-liquid separation in sequence to obtain the 2-alkylanthraquinone product;

[0012] The 2-alkylanthracene oxidation reaction solution comprises: 2-alkylanthracene, 2-alkylanthraquinone, water, hydrophilic impurities, and lipophilic impurities.

[0013] The second aspect of the present invention provides a 2-alkylanthraquinone product obtained by the method provided in the first aspect.

[0014] The third aspect of this invention provides the application of the 2-alkylanthraquinone product provided in the second aspect in the preparation of hydrogen peroxide.

[0015] Compared with the prior art, the present invention has the following advantages:

[0016] (1) The method provided by the present invention uses a complex 2-alkylanthraquinone oxidation reaction solution as raw material. Through the coupling of pervaporation-crystallization-molten water washing phase, it can significantly reduce the energy consumption and operation difficulty of the separation process, greatly reduce the content of trace impurities in the product, and is conducive to obtaining high-purity 2-alkylanthraquinone products, that is, the 2-alkylanthraquinone content in the 2-alkylanthraquinone product is ≥99wt%, the heteroatom content is ≤20ppm, and the total metal content is ≤20ppm; at the same time, the method only introduces water, which can be recycled, and does not introduce other impurities. It has the advantages of simple process, high efficiency, low pollution, and greenness.

[0017] (2) The 2-alkylanthraquinone product obtained by the method provided by the present invention has good single impurity indicators and can be used as a standard of 2-alkylanthraquinone. At the same time, it is used in the study of hydrogen peroxide preparation experiments, which solves the problem of impurities affecting hydrogenation and oxidation efficiency and long-term cycle stability. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the process for separating 2-alkylanthraquinone provided by the present invention.

[0019] Explanation of reference numerals in the attached figures

[0020] 1. 2-alkylanthracene oxidation reaction solution; 2. Water; 3. Solid mixture

[0021] 4. Crystallization 5. Crude 2-alkylanthraquinone crystals 6. Mother liquor for crystallization

[0022] 7. 2-alkylanthraquinone products Detailed Implementation

[0023] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0024] In this invention, unless otherwise specified, "first" and "second" do not indicate a sequence or limit the specific materials or steps; they are merely used to distinguish or indicate that these are not the same material or step. For example, in "first filtration" and "second filtration," "first" and "second" are used only to indicate that these are not the same filtration process.

[0025] The first aspect of the present invention provides a method for separating 2-alkylanthraquinone, the method comprising: sequentially pervaporating, crystallizing and molten washing a 2-alkylanthraquinone oxidation reaction solution to obtain a 2-alkylanthraquinone product with a purity ≥99wt%.

[0026] In some embodiments of the present invention, preferably, the method includes the following steps:

[0027] (1) The 2-alkylanthracene oxidation reaction solution is subjected to pervaporation to obtain water and a solid-liquid mixture with a water content ≤1wt%; the solid-liquid mixture is subjected to a first filtration to obtain a solid mixture rich in hydrophilic impurities, and a crystalline liquid containing 2-alkylanthracene, 2-alkylanthraquinone and lipophilic impurities;

[0028] (2) The crystallization solution is crystallized to obtain crude 2-alkylanthraquinone crystals;

[0029] (3) The crude 2-alkylanthraquinone crystals are subjected to molten water washing, cooling and solid-liquid separation in sequence to obtain the 2-alkylanthraquinone product.

[0030] According to the present invention, unless otherwise specified, impurities in the 2-alkylanthracene oxidation reaction solution include impurities introduced from the reaction raw materials and impurities from side reactions. Specifically, impurities introduced from the raw materials include heteroatoms such as P, Si, N, S, and Cl introduced from the crude 2-alkylanthracene and the solvent; organic acids such as methanesulfonic acid, ethanesulfonic acid, propanesulfonic acid, butanesulfonic acid, perfluoromethanesulfonic acid, perfluoroethanesulfonic acid, perfluoropropanesulfonic acid, and perfluorobutanesulfonic acid, and their oxidation or decomposition products; and Cu. 2+ Fe 3+ It includes non-ferrous metal ion impurities, other anthracene substances, etc.; it also includes soluble compounds and decomposition products of one or more metals from Group IB, Group IVB, Group VB, Group VIIB and Group VIII introduced by oxidation catalysts; side reaction impurities include alkane oxides, aromatic oxides, phthalic anhydrides, other anthraquinone substances, etc.

[0031] In this invention, unless otherwise specified, the hydrophilic impurities in the 2-alkylanthracene oxidation reaction solution include some heteroatoms such as P, Si, N, S, and Cl, sulfonic acid organic acids and their oxidation or decomposition products, and Cu. 2+ Fe 3+The main impurities are non-ferrous metal ions, soluble compounds of various metals introduced by the catalyst and their decomposition products; the rest are mainly lipophilic impurities.

[0032] In some embodiments of the present invention, preferably, the 2-alkylanthraquinone content in the 2-alkylanthraquinone oxidation reaction solution is 3-25 wt%, the 2-alkylanthraquinone content is 0.1-6 wt%, the water content is 2-40 wt%, the hydrophilic impurity content is 0.1-35 wt%, and the lipophilic impurity content is 0.1-10 wt%; more preferably, the 2-alkylanthraquinone content in the 2-alkylanthraquinone oxidation reaction solution is 5-15 wt%, the 2-alkylanthraquinone content is 0.1-3 wt%, the water content is 10-20 wt%, the hydrophilic impurity content is 0.5-10 wt%, and the lipophilic impurity content is 0.5-5 wt%.

[0033] In some embodiments of the present invention, preferably, the 2-alkylanthracene is selected from at least one of 2-butylanthracene, 2-pentylanthracene and 2-hexylanthracene; and the 2-alkylanthraquinone is selected from at least one of 2-butylanthraquinone, 2-pentylanthraquinone and 2-hexylanthraquinone.

[0034] In this invention, the source of the 2-alkylanthracene oxidation reaction solution has a wide range of selection, as long as the 2-alkylanthracene oxidation reaction solution meets the above-mentioned limitations. Preferably, the 2-alkylanthracene oxidation reaction solution is prepared by oxidizing 2-alkylanthracene in the presence of an oxidizing solvent and an oxidizing catalyst.

[0035] In one specific embodiment of the present invention, the 2-alkylanthracene oxidation reaction solution is prepared by the following method: in the presence of an alkylation catalyst and an alkylation solvent, anthracene and an alkylation reagent are subjected to an alkylation reaction, and the resulting product containing 2-alkylanthracene is separated to obtain crude 2-alkylanthracene; in the presence of an oxidizing solvent and an oxidizing catalyst, the crude 2-alkylanthracene is subjected to an oxidizing reaction to obtain the 2-alkylanthracene oxidation reaction solution.

[0036] In this invention, the alkylation catalyst is selected from one or more liquid acids, preferably methanesulfonic acid and / or p-toluenesulfonic acid; based on the total weight of the feed liquid containing anthracene, the alkylation catalyst and the alkylation reaction solvent, the catalyst content is 0.01-50 wt%, preferably 0.5-30 wt%.

[0037] In this invention, the alkylation reaction solvent is C6 or higher, preferably C6-C. 12The solvent is selected from one or more of alkanes, cycloalkanes, and aromatic hydrocarbons; wherein the aromatic hydrocarbon is substituted or unsubstituted, preferably one or more of mono- or poly-substituted benzene derivatives; more preferably one or more of poly-substituted benzene derivatives, wherein the substituent is one or more of C1-C4 alkyl and halogen elements; further preferably, the alkylation reaction solvent is one or more of polyalkyl-substituted benzene derivatives; most preferably, the alkylation reaction solvent is selected from one or more of 1,3,5-trimethylbenzene, 1,2,3,5-tetramethylbenzene, 1,3,4,5-tetramethylbenzene, 1,3,5,6-tetramethylbenzene, and 2,3,5,6-tetramethylbenzene. Based on the total weight of anthracene and the alkylation reaction solvent, the anthracene content is 5-60 wt%, preferably 8-50 wt%.

[0038] In this invention, the alkylating agent is one or more of olefins, alcohols, halogenated hydrocarbons, and ethers containing 2-8 carbon atoms, preferably one or more of olefins, alcohols, halogenated hydrocarbons, and ethers containing 4-6 carbon atoms, and more preferably a monoolefin containing 4-6 carbon atoms. The molar ratio of anthracene to the alkylating agent is 0.2-20:1, preferably 0.5-5:1.

[0039] In this invention, the conditions for the alkylation reaction include: a reaction temperature of 100-250°C, preferably 120-200°C; a reaction pressure of 0-1 MPa, preferably 0.05-0.5 MPa; and a reaction time of 0.01-48 h, preferably 0.5-24 h.

[0040] In this invention, the oxidizing solvent is selected from at least one of methanol, tert-butanol, acetone, N,N-dimethylformamide, N,N-dimethylacetamide, N,N-dimethylpropionamide, N-methylpyrrolidone, and N-ethylpyrrolidone.

[0041] In this invention, the oxidation catalyst is selected from metal catalysts and / or supported catalysts. The metal catalyst is selected from soluble compounds containing at least one metal element from Group IB, Group IVB, Group VB, Group VIIB, and Group VIII, such as chlorates, nitrates, and sulfates. The active component in the supported catalyst is selected from at least one metal from Group IB, Group IVB, Group VB, Group VIIB, and Group VIII, and the support is selected from inorganic heat-resistant oxides, including but not limited to alumina, silicon oxide, etc.

[0042] In this invention, the conditions for the oxidation reaction include: a reaction temperature of 25-100℃, preferably 50-75℃; a reaction pressure of 0.1-0.15MPa, preferably 0.08-0.12MPa; and a reaction time of 1-10h, preferably 3-6h.

[0043] In this invention, water in the solvent of the 2-alkylanthraquinone oxidation reaction is removed by pervaporation, which is simple, efficient and energy-saving. The first filtration effectively removes most of the hydrophilic impurities (e.g., colored ions, metal salts, organic acids, heteroatoms, etc.), which reduces the pressure on crystal nucleation, growth and purity control in the subsequent crystallization steps, and lays a fundamental foundation for obtaining a high-purity 2-alkylanthraquinone product.

[0044] In some embodiments of the present invention, preferably, the conditions for pervaporation include: an operating temperature of 30-80°C, more preferably 55-75°C; a pre-membrane pressure of 0.1-0.4 MPa; and a post-membrane pressure of -0.07 MPa to -0.1 MPa. This ensures high membrane flux, low energy consumption, and maximum water removal, which is beneficial for the precipitation and separation of hydrophilic impurities.

[0045] In some embodiments of the present invention, preferably, the water content in the solid-liquid mixture is ≤0.5wt%. This setting is beneficial for maximizing the removal of hydrophilic impurities in this step.

[0046] In some embodiments of the present invention, preferably, the temperature of the first filter is 40-100°C, for example, 40°C, 50°C, 60°C, 70°C, 80°C, 85°C, 100°C, and any value within the range of any two values, preferably 50-85°C.

[0047] In this invention, the crystallization is intended to remove 2-alkylanthracene and most of the lipophilic impurities from the crystallization solution containing 2-alkylanthracene, 2-alkylanthraquinone and lipophilic impurities, to obtain crude 2-alkylanthraquinone crystals. In addition to 2-alkylanthraquinone, the crude 2-alkylanthraquinone crystals inevitably contain residual hydrophilic impurities, such as heteroatoms, metal elements, etc.

[0048] In some embodiments of the present invention, preferably, in step (2), the crystallization conditions include: an initial temperature of 40-100°C, preferably 50-85°C; and an end temperature of -20 to 5°C, preferably -10 to 0°C.

[0049] In some embodiments of the present invention, preferably, the crystallization is selected from cooling-dissolution coupled crystallization, dissolution crystallization, and cooling crystallization; more preferably, it is selected from cooling-dissolution coupled crystallization and dissolution crystallization, and even more preferably, it is selected from cooling-dissolution coupled crystallization. This setting can precisely balance the crystal nucleation and growth rate, regulate crystal growth, and effectively control the inclusion of impurities in the crystal, laying a key foundation for obtaining high-purity 2-alkylanthraquinone.

[0050] In some embodiments of the present invention, preferably, the solvent used in the crystallization process is water. In this invention, the solvent is primarily derived from water obtained through pervaporation, further saving material consumption.

[0051] In some embodiments of the present invention, preferably, the weight ratio of the solvent to the crystallizing liquid is 1:1-15, for example, 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:10, 1:15, and any value within any range of two such values, preferably 1:2-7. Using these preferred conditions is more conducive to improving the purity of the crude 2-alkylanthraquinone crystals.

[0052] In some embodiments of the present invention, preferably, the cooling-dissolution coupled crystallization is selected from the following methods: crystallization followed by cooling, crystallization followed by cooling, and crystallization while simultaneously cooling. The preferred method is crystallization while simultaneously cooling. All three cooling methods aim to balance and control the crystal nucleation rate and growth rate, thereby regulating the orderly growth of crystals in a crystallization solution containing a relatively large number of impurities, better ensuring crystal quality, and improving purity.

[0053] In this invention, unless otherwise specified, when the crystallization is selected from the process of first dissolving and then cooling, the solvent is first added to the crystallization liquid and then the temperature is lowered; when the crystallization is selected from the process of first cooling and then dissolving, the crystallization liquid is first cooled and then the solvent is added; when the crystallization is selected from the process of simultaneously dissolving and cooling, the addition of the solvent and the cooling are carried out simultaneously.

[0054] In some embodiments of the present invention, preferably, when the crystallization is selected from the process of first dissolution crystallization followed by cooling crystallization, the dissolution crystallization process is divided into four stages. In the first stage, a portion of the solvent is added at a rate of 0.02-0.2 g / (g). 结晶液 ×h); Stage I-2, stabilization period, time is 0.1-1.3h; Stage I-3, the remaining solvent is added at a rate of 0.1-1g / (g) 结晶液 ×h); Phase I-4, the stable period, lasts 0.1-1.3h.

[0055] In some embodiments of the present invention, preferably, in the first stage, the amount of the partially added solvent is 5-25 wt% of the amount of solvent used.

[0056] In some embodiments of the present invention, preferably, in the first and second stages, 2-alkylanthraquinone seed crystals are added, wherein the amount of 2-alkylanthraquinone seed crystals added is 0.01-20 wt% of the 2-alkylanthraquinone product content; preferably 0.5-10 wt%. This configuration, by adding 2-alkylanthraquinone seed crystals in the first and second stages, inhibits explosive nucleation, promotes crystal growth, reduces crystal inclusions, and improves crystal purity.

[0057] In some embodiments of the present invention, preferably, when the crystallization is selected from the process of first dissolution crystallization followed by cooling crystallization, the cooling crystallization process includes: a cooling rate from the initial temperature to the final temperature of 0.1-2℃ / min, preferably 0.5-1℃ / min; and a final crystal growth time of 0.2-6h, preferably 0.5-2h. More preferably, the cooling crystallization process further includes: maintaining the temperature at any temperature between 10-60℃ for 0.1-1.5h. Using these preferred conditions more effectively suppresses crystal growth and consumes supersaturation.

[0058] In some embodiments of the present invention, preferably, when the crystallization is selected from the process of cooling crystallization followed by dissolution crystallization, the cooling crystallization process is divided into four stages: Stage II-1, cooling from the initial temperature to 30-60℃ at a cooling rate of 0.01-0.1℃ / min; Stage II-2, isothermal stage, for 0.2-1h; Stage II-3, continuing to cool to the final temperature at a cooling rate of 0.1-2℃ / min; Stage II-4, isothermal crystal growth stage, for 0.2-2h.

[0059] In some embodiments of the present invention, more preferably, in stage II-1, the initial temperature is reduced to 40-55℃ at a cooling rate of 0.02-0.05℃ / min; in stage II-2, a constant temperature stage lasting 0.4-0.8h; in stage II-3, the temperature is further reduced to the final temperature at a cooling rate of 0.2-1℃ / min; and in stage II-4, a constant temperature crystal growth stage lasting 0.5-1h.

[0060] In some embodiments of the present invention, preferably, in the II-2 stage, 2-alkylanthraquinone seed crystals are added, wherein the amount of 2-alkylanthraquinone seed crystals added is 0.01-20 wt% of the 2-alkylanthraquinone product content; preferably 0.5-10 wt%. This configuration, by adding 2-alkylanthraquinone seed crystals in the II-2 stage, inhibits explosive nucleation, promotes crystal growth, reduces crystal inclusions, and improves crystal purity.

[0061] In some embodiments of the present invention, preferably, when the crystallization is selected from the process of cooling crystallization followed by dissolution crystallization, the dissolving agent is used at a concentration of 0.1-1 g / (g) during the dissolution crystallization process. 结晶液The solvent is added at a rate of 0.2-0.8 g / (g·h), and then crystallized at a constant temperature for 0.1-1.3 h; more preferably, the solvent is added at a rate of 0.2-0.8 g / (g·h). 结晶液 The solvent is added at a rate of (×h), and then the crystals are grown at a constant temperature for 0.5-1h. More preferably, when the amount of solvent added is 1 / 3-2 / 3 of the total amount of solvent used, the process is paused for 0.5-1h, and the remaining solvent is added. Using these preferred conditions, crystal growth is more effectively controlled, and supersaturation is consumed.

[0062] In some embodiments of the present invention, preferably, when the crystallization is selected from simultaneous dissolution crystallization and cooling crystallization, the simultaneous dissolution crystallization and cooling crystallization process is divided into six stages. In stage III-1, a first portion of the solvent is added and the temperature is lowered, with an addition rate of 0.01-0.1 g / (g) 结晶液 ×h), cooling rate is 0.1-0.5℃ / min, cooling to 35-60℃; Stage III-2, stabilization period, isothermal time is 0.1-1.3h; Stage III-3, addition of the second part of the solvent and cooling, addition rate is 0.1-0.5g / (g 结晶液 ×h), cooling rate is 0.2-1℃ / min; cooling to 10-35℃; stage III-4, stabilization period, isothermal time is 0.2-2h; stage III-5, addition of the third part of the solvent and cooling, addition rate is 0.1-1g / (g 结晶液 The cooling rate is 0.5-2℃ / min, reaching the final temperature. In stages III-6, crystal growth is carried out at a constant temperature for 0.2-6 hours. Stage III-4 effectively controls crystal growth and consumes supersaturation; stages III-6 improve crystal yield.

[0063] In some embodiments of the present invention, preferably, the weight ratio of the first part of the solvent, the second part of the solvent, and the third part of the solvent is 5-15:10-45:40-80. By feeding and matching the three parts of the solvent, a balance between crystal nucleation and growth rate is achieved, ensuring crystal quality and reducing the introduction of impurities.

[0064] In some embodiments of the present invention, preferably, in stage III-2, 2-alkylanthraquinone seed crystals are added, wherein the amount of 2-alkylanthraquinone seed crystals added is 0.01-20 wt% of the 2-alkylanthraquinone product content, preferably 0.5-10 wt%. This configuration, by adding 2-alkylanthraquinone seed crystals in stage III-2, inhibits explosive nucleation, promotes crystal growth, reduces crystal inclusions, and improves crystal purity.

[0065] In some embodiments of the present invention, preferably, the crystallized product is subjected to a second filtration to obtain the crude 2-alkylanthraquinone crystals and a mother liquor, wherein the mother liquor contains 2-alkylanthracene and lipophilic impurities. More preferably, the temperature of the second filtration is -20 to 5°C, more preferably -10 to 0°C.

[0066] In some embodiments of the present invention, preferably, the method further includes: returning the crystallization mother liquor and mixing it into the 2-alkylanthracene oxidation reaction solution to perform the pervaporation.

[0067] In this invention, the melt washing is intended to remove residual hydrophilic impurities, such as heteroatoms and metal ions, from the crude 2-alkylanthraquinone crystals. Preferably, in step (3), the melt washing process involves melting the crude 2-alkylanthraquinone crystals and water to obtain a mixture.

[0068] In this invention, a melt-washing technique, namely liquid-liquid extraction, is used to easily and efficiently remove trace amounts of hydrophilic impurities in 2-alkylanthraquinone, which plays a decisive role in obtaining high-purity 2-alkylanthraquinone.

[0069] In some embodiments of the present invention, preferably, the weight ratio of the crude 2-alkylanthraquinone crystals to water is 0.1-10:1, for example, 0.1:1, 0.5:1, 1:1, 2:1, 3:1, 5:1, 8:1, 10:1, and any value within the range of any two values, preferably 0.5-5:1.

[0070] In some embodiments of the present invention, preferably, the conditions for the melt washing include: temperature ≥ 60°C, preferably 60-100°C; time 0.1-5h, preferably 0.5-3h.

[0071] In this invention, the cooling is intended to utilize the phase transition characteristic of 2-alkylanthraquinone in the mixture at low temperatures to solidify the 2-alkylanthraquinone, followed by solid-liquid separation to obtain the 2-alkylanthraquinone product. Preferably, the cooling temperature is ≤45°C, and more preferably 20-45°C.

[0072] According to the present invention, preferably, the method further includes: repeating step (3) 1-5 times to obtain the 2-alkylanthraquinone product.

[0073] In some embodiments of the present invention, preferably, step (3) is repeated 1-5 times with the solid product obtained from the solid-liquid separation to obtain the 2-alkylanthraquinone product.

[0074] The method provided by this invention, targeting the complex 2-alkylanthraquinone oxidation reaction solution, can significantly reduce the energy consumption and operational difficulty of the separation process through pervaporation-crystallization-melt water washing coupling, greatly reduce the content of trace impurities in the product, and is conducive to obtaining high-purity 2-alkylanthraquinone products.

[0075] The second aspect of the present invention provides a 2-alkylanthraquinone product obtained by the method provided in the first aspect.

[0076] According to the present invention, preferably, the 2-alkylanthraquinone product contains ≥99.5 wt% 2-alkylanthraquinone; the heteroatom content is ≤20 ppm, preferably ≤15 ppm; and the total metal content is ≤20 ppm, preferably ≤5 ppm. Wherein, heteroatom content refers to the content of single heteroatoms, and heteroatoms include, but are not limited to, P, N, Cl, S, and Si.

[0077] In this invention, unless otherwise specified, the 2-alkylanthraquinone content parameter is determined according to GB / T23672-2009; the heteroatom content parameter is determined according to GB / T 17476-1998; and the metal content parameter is determined according to SH / T 0715-2002.

[0078] The third aspect of this invention provides the application of the 2-alkylanthraquinone product provided in the second aspect in the preparation of hydrogen peroxide.

[0079] According to a particularly preferred embodiment of the present invention, a method for separating 2-alkylanthraquinones, the method comprising:

[0080] (1) The 2-alkylanthracene oxidation reaction solution is pervaporated to obtain water and a solid-liquid mixture with a water content ≤0.5wt%; the solid-liquid mixture is filtered for the first time to obtain a solid mixture rich in hydrophilic impurities and a crystalline liquid containing 2-alkylanthracene, 2-alkylanthraquinone and lipophilic impurities;

[0081] (2) The crystallization solution is crystallized to obtain crude 2-alkylanthraquinone crystals;

[0082] (3) The crude 2-alkylanthraquinone crystals were sequentially subjected to melt washing, cooling, and solid-liquid separation to obtain the 2-alkylanthraquinone product;

[0083] The 2-alkylanthraquinone content in the 2-alkylanthraquinone oxidation reaction solution is 5-15 wt%; the 2-alkylanthraquinone content is 0.1-3 wt%; the water content is 10-20 wt%; the hydrophilic impurity content is 0.5-10 wt%; and the lipophilic impurity content is 0.5-5 wt%.

[0084] Wherein, the 2-alkylanthracene is selected from at least one of 2-butylanthracene, 2-pentylanthracene, and 2-hexylanthracene; the 2-alkylanthraquinone is selected from at least one of 2-butylanthraquinone, 2-pentylanthraquinone, and 2-hexylanthraquinone;

[0085] The crystallization is selected from cooling-dissolution coupled crystallization, which is selected from dissolution crystallization followed by cooling crystallization, cooling crystallization followed by dissolution crystallization, and simultaneous dissolution crystallization and cooling crystallization.

[0086] In the process of precipitation and crystallization, the solvent is selected from water; the weight ratio of the solvent to the crystallization liquid is 1:2-7; the water obtained in step (1) is returned and mixed into the solvent.

[0087] The present invention will be described in detail below through embodiments.

[0088] The 2-alkylanthraquinone content parameter was determined according to GB / T 23672-2009; the heteroatom content parameter was determined according to GB / T17476-1998; and the metal content parameter was determined according to SH / T 0715-2002.

[0089] The 2-alkylanthraquinone content in the 2-alkylanthraquinone oxidation reaction solution A1 is 7.3 wt%, the 2-alkylanthraquinone content is 0.5 wt%, the water content is 18.8 wt%, the hydrophilic impurity content is 1 wt%, and the lipophilic impurity content is 0.7 wt%.

[0090] The 2-alkylanthraquinone content in the 2-alkylanthraquinone oxidation reaction solution A2 is 6.9 wt%, the 2-alkylanthraquinone content is 0.5 wt%, the water content is 15.3 wt%, the hydrophilic impurity content is 0.7 wt%, and the lipophilic impurity content is 1.1 wt%.

[0091] The 2-alkylanthraquinone content in the 2-alkylanthraquinone oxidation reaction solution A3 is 10.3 wt%, the 2-alkylanthraquinone content is 0.7 wt%, the water content is 17.5 wt%, the hydrophilic impurity content is 4 wt%, and the lipophilic impurity content is 1.5 wt%.

[0092] Example 1

[0093] (1) 2014g of 2-alkylanthracene (a mixture of 2-butylanthracene, 2-pentylanthracene and 2-hexylanthracene) oxidation reaction solution A1 was pervaporated (operating temperature 65℃; pre-membrane pressure 0.3MPa; post-membrane pressure -0.08MPa) to obtain 402g of water and a solid-liquid mixture with a water content of 0.3wt%; the above solid-liquid mixture was filtered at 65℃ to obtain 17.2g of solid mixture (rich in hydrophilic impurities) and 1594.8g of crystallization solution (containing 2-alkylanthracene, 2-alkylanthraquinone and lipophilic impurities);

[0094] (2) The above crystallizing liquid was subjected to simultaneous dissolution and cooling crystallization. The total amount of solvent (water) was 797.4g (including 402g of water obtained by pervaporation treatment).

[0095] In stage III-1, a solvent is added and the temperature is lowered. The solvent is added at a rate of 0.05 g / (g) 结晶液 ×h); the initial temperature is 65℃, and the cooling rate is 0.1℃ / min; when the temperature drops to 55℃, the addition of solvent and cooling are stopped simultaneously; in stage III-2, the stabilization period, 8.4g of 2-alkylanthraquinone seed crystals are added for 0.5h; in stage III-3, the solvent and cooling are started simultaneously, and the solvent addition rate is 0.1g / (g) 结晶液 ×h), cooling rate is 0.5℃ / min; cooling to 15℃; stage III-4, stabilization period, isothermal time is 0.5h; stage III-5, continue adding solvent and cooling, solvent addition rate is 0.5g / (g 结晶液 ×h), cooling rate is 0.5℃ / min until the solvent is completely added and the temperature is reduced to the final temperature of -10℃; in stages III-6, crystallization is carried out at constant temperature for 0.5h, followed by constant temperature filtration to obtain 145.7g of crude 2-alkylanthraquinone crystals and crystallization mother liquor (containing lipophilic impurities, 2-alkylanthracene and water).

[0096] In stages III-1, III-3, and III-5, the weight ratio of the solvent is 8.3:13.3:78.4.

[0097] (3) The above crude 2-alkylanthraquinone crystals and water were melt-washed in a weight ratio of 1:1 (temperature 80℃, time 1h). The resulting mixture was cooled to below 45℃ and the solid and liquid were separated to obtain 143.8g of solid 2-alkylanthraquinone product S1.

[0098] Among them, the purity of 2-alkylanthraquinone product S1 was 99.6 wt%, and the yield was 91%.

[0099] Based on the total weight of 2-alkylanthraquinone product S1, the content of 2-butylanthraquinone is 16.1 wt%, the content of 2-pentylanthraquinone is 82.1 wt%, the content of 2-hexylanthraquinone is 1.4 wt%, the content of N is 2.5 ppm, the content of Cl is 0.7 ppm, the content of S is 11 ppm, and the total metal content is 3.7 ppm.

[0100] Example 2

[0101] (1) 382g of 2-alkylanthracene (2-pentylanthracene) oxidation reaction solution A2 was pervaporated (operating temperature 60℃; pre-membrane pressure 0.25MPa; post-membrane pressure -0.08MPa) to obtain 61g of water and a solid-liquid mixture with a water content of 0.5wt%; the above solid-liquid mixture was filtered at 55℃ to obtain 2.2g of solid mixture (rich in hydrophilic impurities) and 318.8g of crystallization solution (containing 2-alkylanthracene, 2-alkylanthraquinone and lipophilic impurities);

[0102] (2) The above crystallization solution is first dissolved and crystallized, and then cooled and crystallized. The total amount of solvent (water) is 108g (including 61g of water obtained by pervaporation treatment);

[0103] The crystallization process is divided into four stages. In stage I-1, the solvent addition rate is 0.03 g / (g) 结晶液 ×h), add 27g and then stop; in stage I-2, add 0.5g of 2-pentylanthraquinone seed crystals and stir at a constant temperature for 1h; in stage I-3, continue to add solvent at a rate of 0.3g / (g) 结晶液 After the addition of the ingredients (×h), the mixture was stirred at a constant temperature for 0.3h. Then, the mixture was cooled and crystallized at a rate of 0.5℃ / min from 55℃ to -15℃. The mixture was kept at a constant temperature for 2h, and then filtered at a constant temperature to obtain 28.2g of crude 2-pentylanthraquinone crystals and a mother liquor.

[0104] (3) The above 2-pentylanthraquinone crystals and water were melt-washed at a weight ratio of 10:1 (temperature 70°C, time 2.5h). The resulting mixture was cooled to below 45°C and the solid and liquid were separated. Step (3) was repeated 3 times to obtain 25.9g of solid 2-pentylanthraquinone product S2.

[0105] The purity of 2-pentylanthraquinone product S2 was 99.8 wt%, and the yield was 92.2%.

[0106] Based on the total weight of 2-pentylanthraquinone product S2, the content of 2-pentylanthraquinone is 99.8 wt%, the content of N is 6 ppm, the content of Cl is 0.7 ppm, the content of S is 15 ppm, and the total metal content is 4.2 ppm.

[0107] Example 3

[0108] (1) 2857g of 2-alkylanthracene (a mixture of 2-butylanthracene and 2-pentylanthracene) oxidation reaction solution A3 was pervaporated (operating temperature 55℃; pre-membrane pressure 0.4MPa; post-membrane pressure -0.095MPa) to obtain 526g of water and a solid-liquid mixture with a water content of 0.2wt%; the above solid-liquid mixture was filtered at 65℃ to obtain 43.8g of solid mixture (rich in hydrophilic impurities) and 2287.2g of crystallization solution (containing 2-alkylanthracene, 2-alkylanthraquinone and lipophilic impurities);

[0109] (2) The above crystallizing solution was subjected to simultaneous dissolution and cooling crystallization. The total amount of solvent (water) was 797.4g (including 526g of water obtained by pervaporation treatment).

[0110] In stage III-1, a solvent was added and the temperature was lowered. The solvent was added at a rate of 0.08 g / (g) 结晶液 ×h); the initial temperature is 60℃, and the cooling rate is 0.3℃ / min; when the temperature drops to 45℃, the addition of solvent and cooling are stopped simultaneously; in stage III-2, the stabilization period, 15.2g of 2-alkylanthraquinone seed crystals are added for 0.5h; in stage III-3, the solvent and cooling are started simultaneously, and the solvent addition rate is 0.5g / (g) 结晶液 ×h), cooling rate is 0.5℃ / min; cooling to 20℃; stage III-4, stabilization period, isothermal time is 0.5h; stage III-5, continue adding solvent and cooling, solvent addition rate is 0.8g / (g 结晶液 ×h), cooling rate is 1℃ / min until the solvent is completely added and the temperature is reduced to the final temperature of 0℃; in stages III-6, crystallization is carried out at constant temperature for 0.5h, followed by constant temperature filtration to obtain 287.3g of crude 2-alkylanthraquinone crystals and crystallization mother liquor (containing lipophilic impurities, 2-alkylanthracene and water);

[0111] In stages III-1, III-3, and III-5, the weight ratio of the solvent is 6.6:41.1:52.3.

[0112] (3) The above crude 2-alkylanthraquinone crystals and water were melt-washed in a weight ratio of 1:1 (temperature 90℃, time 0.5h). The resulting mixture was cooled to below 45℃ and the solid and liquid were separated to obtain 287.1g of solid 2-alkylanthraquinone product S3.

[0113] The purity of 2-alkylanthraquinone product S3 was 99.6 wt%, and the yield was 91.8%.

[0114] Based on the total weight of 2-alkylanthraquinone product S3, the content of 2-butylanthraquinone is 15.1 wt%, the content of 2-pentylanthraquinone is 84.5 wt%, the content of N is 4.7 ppm, the content of Cl is 1.6 ppm, the content of S is 8 ppm, and the total metal content is 4.7 ppm.

[0115] Example 4

[0116] The method of Example 1 is different except that step (2) is different. That is, the crystallization liquid obtained in step (1) is cooled and crystallized first and then dissolved and crystallized. The total amount of solvent (water) used is 797.4g (including 402g of water obtained from reverse osmosis membrane treatment).

[0117] The cooling crystallization process is divided into four stages: Stage II-1, the initial temperature is reduced from 65℃ to 55℃ at a cooling rate of 0.5℃ / min; Stage II-2, a constant temperature stage, involves adding 8.4g of 2-alkylanthraquinone seed crystals for 0.9h; Stage II-3, cooling continues to the final temperature of -10℃ at a cooling rate of 0.8℃ / min; Stage II-4 is a constant temperature crystal growth stage for 1h; during the dissolution crystallization process, the dissolving agent is applied at a rate of 0.8g / (g 结晶液 The solvent was added at a rate of ×h, and then kept at a constant temperature for 0.5h to grow crystals. When the amount of solvent added was 2 / 3 of the total amount of solvent, the process was paused for 0.5h, and the remaining solvent was added to grow crystals at a constant temperature for 0.5h. The mixture was then filtered at a constant temperature to obtain crude 2-alkylanthraquinone crystals and crystallization mother liquor.

[0118] Under the same conditions, the purity of the 2-alkylanthraquinone product S4 was 99.3 wt%, and the yield was 89%.

[0119] Based on the total weight of 2-alkylanthraquinone product S4, the content of 2-butylanthraquinone is 13.2 wt%, the content of 2-pentylanthraquinone is 85.5 wt%, and the content of 2-hexylanthraquinone is 0.6 wt%; the content of N is 8 ppm, the content of Cl is 8.5 ppm, the content of S is 12 ppm, and the total metal content is 3.8 ppm.

[0120] Example 5

[0121] The method of Example 1 is different except that step (2) is different. That is, the crystallizing liquid at 65°C is cooled and crystallized at a cooling rate of 0.1°C / min, cooled to -10°C, and filtered at a constant temperature to obtain crude 2-alkylanthraquinone crystals and crystallizing mother liquor.

[0122] Under the same conditions, the purity of the 2-alkylanthraquinone product S5 was 99.5 wt%, and the yield was 85%.

[0123] Based on the total weight of 2-alkylanthraquinone product S5, the content of 2-butylanthraquinone is 14.6 wt%, the content of 2-pentylanthraquinone is 84.2 wt%, and the content of 2-hexylanthraquinone is 0.7 wt%; the content of N is 10 ppm, the content of Cl is 19 ppm, the content of S is 15 ppm, and the total metal content is 18 ppm.

[0124] Example 6

[0125] The method of Example 1 is different except that step (2) is different, that is, the crystallization liquid at 65°C is dissolved and crystallized, and the total amount of solvent (water) is 797.4g (including 402g of water obtained from reverse osmosis membrane treatment);

[0126] The crystallization process is divided into four stages. In stage I-1, the solvent addition rate is 0.03 g / (g) 结晶液 ×h), add 126g and stop; in stage I-2, add 0.5g of 2-alkylanthraquinone seed crystals and stir at a constant temperature for 1h; in stage I-3, continue to add solvent at a rate of 0.3g / (g) 结晶液 After the addition of the ingredients (×h), the mixture was stirred at a constant temperature for 0.3h, and then filtered at a constant temperature to obtain crude 2-alkylanthraquinone crystals and a mother liquor for crystallization.

[0127] Under the same conditions, the purity of the 2-alkylanthraquinone product S6 was 99.7 wt%, and the yield was 81%.

[0128] Based on the total weight of 2-alkylanthraquinone product S6, the content of 2-butylanthraquinone is 8.4 wt%, the content of 2-pentylanthraquinone is 91.2 wt%, the content of 2-hexylanthraquinone is 0.1 wt%, the content of N is 2.2 ppm, the content of Cl is 1.4 ppm, the content of S is 8 ppm, and the total metal content is 4.8 ppm.

[0129] Example 7

[0130] The method of Example 1 is different except that in step (1), the conditions of pervaporation are adjusted so that the water content in the solid-liquid mixture is 1 wt%, and the other conditions are the same, so that the purity of the 2-alkylanthraquinone product S7 is 99.1 wt% and the yield is 90%.

[0131] Based on the total weight of 2-alkylanthraquinone product S7, the content of 2-butylanthraquinone is 16wt%, the content of 2-pentylanthraquinone is 81.8wt%, and the content of 2-hexylanthraquinone is 1.3wt%; the content of N is 13ppm, the content of Cl is 19ppm, the content of S is 8ppm, and the total metal content is 18.5ppm.

[0132] Comparative Example 1

[0133] 2160g of 2-alkylanthracene (a mixture of 2-butylanthracene, 2-pentylanthracene, and 2-hexylanthracene) oxidation reaction solution A1 was fed into a vacuum distillation system for direct multi-stage vacuum distillation.

[0134] The above-mentioned extract was subjected to a first vacuum distillation (temperature 81.5℃; pressure 10kPa; theoretical plate number 30; reflux ratio 2), yielding solvent at the top and a mixture containing 2-alkylanthracene and 2-alkylanthraquinone at the bottom. This mixture was then subjected to a second vacuum distillation (temperature 180-230℃; pressure 0.5kPa; theoretical plate number 45; reflux ratio 4), yielding a fraction containing 2-alkylanthracene at the top and a mixture containing 2-alkylanthraquinone at the bottom. Finally, this mixture was subjected to a third vacuum distillation (temperature 230-260℃; pressure 0.5kPa; theoretical plate number 45; reflux ratio 5), yielding a fraction containing 2-alkylanthraquinone as crude 2-alkylanthraquinone at the bottom, and also yielding a mixture rich in heavy component impurities.

[0135] The crude 2-alkylanthraquinone was cooled and crystallized. The crude 2-alkylanthraquinone was dissolved in a crystallization solvent (methanol and hexanol) at 55°C, with a weight ratio of methanol, hexanol, and crude 2-alkylanthraquinone of 0.4:0.4:1. The temperature was maintained for 0.3 h; then lowered to 40°C for 2 h, and 8.5 g of seed crystals were added. The temperature was maintained for 0.5 h; then lowered to -10°C for 3 h and maintained for 0.3 h. The mixture was filtered while cold, and the resulting 2-alkylanthraquinone crystals were vacuum dried to obtain 170 g of the 2-alkylanthraquinone product DS1.

[0136] Among them, the purity of 2-alkylanthraquinone product DS1 was 98.5 wt%, and the yield was 84%.

[0137] Based on the total weight of DS1, a 2-alkylanthraquinone product, the content of 2-butylanthraquinone is 14 wt%, the content of 2-pentylanthraquinone is 82.8 wt%, and the content of 2-hexylanthraquinone is 1.7 wt%; the content of N is 38 ppm, the content of Cl is 25 ppm, the content of S is 140 ppm, the content of Si is 43 ppm, and the total metal content is 18 ppm.

[0138] Comparative Example 2

[0139] The method of Example 1 is the same, except that step (3) is omitted, and the crude 2-alkylanthraquinone crystals obtained in step (2) are directly used as the 2-alkylanthraquinone product DS2.

[0140] Among them, the purity of DS2, a 2-alkylanthraquinone product, was 99.6 wt%, and the yield was 91%.

[0141] Based on the total weight of the 2-alkylanthraquinone product DS2, the content of 2-butylanthraquinone is 16.1 wt%, the content of 2-pentylanthraquinone is 82.1 wt%, and the content of 2-hexylanthraquinone is 1.4 wt%; the content of N is 46.9 ppm, the content of Cl is 35 ppm, the content of S is 64 ppm, and the total metal content is 168 ppm.

[0142] Compared with Comparative Examples 1-2, the 2-alkylanthraquinone product prepared by the method provided by this invention not only has high purity, but also effectively reduces the total impurity content and metal content in the 2-alkylanthraquinone product. That is, the 2-alkylanthraquinone content in the 2-alkylanthraquinone product is ≥99wt%, the heteroatom content is ≤20ppm, and the total metal content is ≤20ppm. At the same time, the 2-alkylanthraquinone product prepared by the method provided by this invention has good individual impurity indicators and can be used as a standard for 2-alkylanthraquinone.

[0143] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for separating 2-alkylanthraquinone, characterized in that, The method includes the following steps: (1) The 2-alkylanthracene oxidation reaction solution is pervaporated to obtain water and a solid-liquid mixture with a water content ≤1wt%; the solid-liquid mixture is filtered for the first time to obtain a solid mixture rich in hydrophilic impurities and a crystalline liquid containing 2-alkylanthracene, 2-alkylanthraquinone and lipophilic impurities; (2) The crystallization solution is crystallized to obtain crude 2-alkylanthraquinone crystals; (3) The crude 2-alkylanthraquinone crystals are sequentially subjected to melt washing, cooling, and solid-liquid separation to obtain the 2-alkylanthraquinone product; The 2-alkylanthracene oxidation reaction solution comprises: 2-alkylanthracene, 2-alkylanthraquinone, water, hydrophilic impurities, and lipophilic impurities; The 2-alkylanthraquinone content in the 2-alkylanthraquinone oxidation reaction solution is 3-25 wt%; the 2-alkylanthraquinone content is 0.1-6 wt%; the water content is 2-40 wt%; the hydrophilic impurity content is 0.1-35 wt%; and the lipophilic impurity content is 0.1-10 wt%.

2. The method according to claim 1, wherein, The 2-alkylanthraquinone content in the 2-alkylanthraquinone oxidation reaction solution is 5-15 wt%; the 2-alkylanthraquinone content is 0.1-3 wt%; the water content is 10-20 wt%; the hydrophilic impurity content is 0.5-10 wt%; and the lipophilic impurity content is 0.5-5 wt%. And / or, the 2-alkylanthraquinone is selected from at least one of 2-butylanthraquinone, 2-pentylanthraquinone, and 2-hexylanthraquinone; the 2-alkylanthraquinone is selected from at least one of 2-butylanthraquinone, 2-pentylanthraquinone, and 2-hexylanthraquinone.

3. The method according to claim 1, wherein, In step (1), the conditions for pervaporation include: an operating temperature of 30-80℃; a membrane inlet pressure of 0.1-0.4MPa; and a membrane outlet pressure of -0.07MPa to -0.1MPa. And / or, the water content in the solid-liquid mixture is ≤0.5wt%; And / or, the temperature of the first filter is 40-100°C.

4. The method according to claim 3, wherein, In step (1), the conditions for pervaporation include: an operating temperature of 55-75℃; And / or, the temperature of the first filter is 50-85°C.

5. The method according to any one of claims 1-4, wherein, In step (2), the crystallization conditions include: an initial temperature of 40-100℃ and an ending temperature of -20 to 5℃; And / or, the crystallization is selected from cooling-dissolution coupled crystallization, dissolution crystallization, and cooling crystallization.

6. The method according to claim 5, wherein, In step (2), the crystallization conditions include: an initial temperature of 50-85℃ and an ending temperature of -10 to 0℃; And / or, the crystallization is a cooling-dissolution coupled crystallization or dissolution crystallization.

7. The method according to claim 5, wherein, The cooling-dissolution coupled crystallization is selected from the following methods: first dissolution crystallization followed by cooling crystallization, first cooling crystallization followed by dissolution crystallization, and simultaneous dissolution crystallization and cooling crystallization. And / or, in the process of said crystallization, the solvent is selected from water.

8. The method according to claim 7, wherein, The weight ratio of the solvent to the crystallizing liquid is 1:1-15; And / or, the water obtained in step (1) is returned and mixed into the solvent.

9. The method according to claim 7, wherein, The cooling-dissolution coupled crystallization involves simultaneous dissolution crystallization and cooling crystallization.

10. The method according to claim 7, wherein, The weight ratio of the solvent to the crystallizing liquid is 1:2-7.

11. The method according to claim 7, wherein, When the crystallization is selected from the process of first dissolution crystallization followed by cooling crystallization, the dissolution crystallization process is divided into four stages. In the first stage, a portion of the solvent is added at a rate of 0.02-0.2 g / (g). 结晶液 ×h); Stage I-2, stabilization period, time is 0.1-1.3h; Stage I-3, the remaining solvent is added at a rate of 0.1-1g / (g) 结晶液 ×h); Phase I-4, the stable period, lasts 0.1-1.3h.

12. The method according to claim 11, wherein, In stage I-1, the amount of the partially added solvent is 5-25 wt% of the solvent dosage.

13. The method according to claim 11, wherein, In stage I-2, 2-alkylanthraquinone seed crystals are added, and the amount of 2-alkylanthraquinone seed crystals added is 0.01-20 wt% of the 2-alkylanthraquinone product content.

14. The method according to claim 13, wherein, In stage I-2, 2-alkylanthraquinone seed crystals are added, and the amount of 2-alkylanthraquinone seed crystals added is 0.5-10 wt% of the 2-alkylanthraquinone product content.

15. The method according to claim 7, wherein, When the crystallization is selected from the process of first dissolution crystallization and then cooling crystallization, the cooling crystallization process includes: a cooling rate of 0.1-2℃ / min from the initial temperature to the final temperature; and a final crystal growth time of 0.2-6h.

16. The method according to claim 7, wherein, When the crystallization is selected from the process of first dissolution crystallization and then cooling crystallization, the cooling crystallization process further includes: cooling the temperature to any temperature between 10-60℃ and holding it at that temperature for 0.1-1.5 hours.

17. The method according to claim 15, wherein, When the crystallization is selected from the process of first dissolution crystallization and then cooling crystallization, the cooling crystallization process includes: a cooling rate of 0.5-1℃ / min from the initial temperature to the final temperature; and a final crystal growth time of 0.5-2h.

18. The method according to claim 7, wherein, When the crystallization is selected from the process of cooling crystallization followed by dissolution crystallization, the cooling crystallization process is divided into four stages: Stage II-1, cooling from the initial temperature to 30-60℃ at a cooling rate of 0.01-0.1℃ / min; Stage II-2, isothermal stage, for 0.2-1h; Stage II-3, continuing to cool to the final temperature at a cooling rate of 0.1-2℃ / min; Stage II-4, isothermal crystal growth stage, for 0.2-2h.

19. The method according to claim 18, wherein, In stage II-1, the initial temperature is reduced to 40-55℃ at a rate of 0.02-0.05℃ / min; in stage II-2, the temperature is maintained at a constant temperature for 0.4-0.8 hours; in stage II-3, the temperature is further reduced to the final temperature at a rate of 0.2-1℃ / min; and in stage II-4, the temperature is maintained at a constant temperature for crystal growth for 0.5-1 hours.

20. The method according to claim 18, wherein, In stage II-2, 2-alkylanthraquinone seed crystals are added, and the amount of 2-alkylanthraquinone seed crystals added is 0.01-20 wt% of the 2-alkylanthraquinone product content.

21. The method according to claim 20, wherein, In stage II-2, 2-alkylanthraquinone seed crystals are added, and the amount of 2-alkylanthraquinone seed crystals added is 0.5-10 wt% of the 2-alkylanthraquinone product content.

22. The method according to claim 7, wherein, When the crystallization is selected from the process of cooling crystallization followed by dissolution crystallization, during the dissolution crystallization process, the dissolving agent is used at a concentration of 0.1-1 g / (g). 结晶液 The crystals are added at a rate of ×h, and then kept at a constant temperature for 0.1-1.3h.

23. The method according to claim 22, wherein, When the crystallization is selected from the process of cooling crystallization followed by dissolution crystallization, the dissolving agent is used at a concentration of 0.2-0.8 g / (g) during the dissolution crystallization process. 结晶液 The mixture was added at a rate of ×h, and then kept at a constant temperature for 0.5-1h to grow crystals.

24. The method according to claim 23, wherein, When the crystallization is selected from the process of cooling crystallization followed by dissolution crystallization, during the dissolution crystallization process, when the amount of the dissolution agent added is 1 / 3 to 2 / 3 of the amount of the dissolution agent used, the process is paused for 0.5 to 1 hour, and the remaining dissolution agent is added.

25. The method according to claim 7, wherein, When the crystallization is selected from the simultaneous dissolution crystallization and cooling crystallization process, the simultaneous dissolution crystallization and cooling crystallization process is divided into six stages. In stage III-1, the first part of the solvent is added and the temperature is lowered, with an addition rate of 0.01-0.1 g / (g) 结晶液 ×h), cooling rate is 0.1-0.5℃ / min, cooling to 35-60℃; Stage III-2, stabilization period, isothermal time is 0.1-1.3h; Stage III-3, addition of the second part of the solvent and cooling, addition rate is 0.1-0.5g / (g 结晶液 ×h), cooling rate is 0.2-1℃ / min; cooling to 10-35℃; stage III-4, stabilization period, isothermal time is 0.2-2h; stage III-5, addition of the third part of the solvent and cooling, addition rate is 0.1-1g / (g 结晶液 ×h), cooling rate is 0.5-2℃ / min, down to the final temperature; Stage III-6, constant temperature crystal growth for 0.2-6h.

26. The method of claim 25, wherein, The weight ratio of the first part of the solvent, the second part of the solvent, and the third part of the solvent in the solvent is 5-15:10-45:40-80.

27. The method according to claim 25, wherein, In stage III-2, 2-alkylanthraquinone seed crystals are added, and the amount of 2-alkylanthraquinone seed crystals added is 0.01-20 wt% of the 2-alkylanthraquinone product content.

28. The method according to claim 27, wherein, When the crystallization is selected from the simultaneous dissolution crystallization and cooling crystallization, in the III-2 stage, 2-alkylanthraquinone seed crystals are added, and the amount of 2-alkylanthraquinone seed crystals added is 0.5-10 wt% of the 2-alkylanthraquinone product content.

29. The method according to any one of claims 1-4, wherein, In step (2), the crystallized product is subjected to a second filtration to obtain the crude 2-alkylanthraquinone crystals and the mother liquor for crystallization.

30. The method according to claim 29, wherein, In step (2), the method further includes: returning the crystallization mother liquor and mixing it into the 2-alkylanthracene oxidation reaction solution.

31. The method according to claim 29, wherein, In step (2), the temperature of the second filter is -20 to 5°C.

32. The method according to claim 31, wherein, In step (2), the temperature of the second filter is -10 to 0°C.

33. The method according to any one of claims 1-4, wherein, In step (3), the melt washing process includes: melting and washing the crude 2-alkylanthraquinone crystals with water to obtain a mixture; And / or, the conditions for the melt washing include: temperature ≥ 60°C; time 0.1-5 h; And / or, the cooling conditions include: temperature ≤ 45°C.

34. The method according to claim 33, wherein, In step (3), the weight ratio of the crude 2-alkylanthraquinone crystals to water is 0.1-10:

1.

35. The method according to claim 34, wherein, In step (3), the weight ratio of the crude 2-alkylanthraquinone crystals to water is 0.5-5:

1.

36. The method according to claim 33, wherein, In step (3), the conditions for the melt washing include: a temperature of 60-100℃ and a time of 0.5-3h.

37. The method according to claim 33, wherein, In step (3), the cooling conditions include a temperature of 20-45°C.

38. The method according to any one of claims 1-4, wherein, The method further includes repeating step (3) 1-5 times to obtain the 2-alkylanthraquinone product.

39. The method according to any one of claims 1-4, wherein, The 2-alkylanthraquinone product obtained by the method has a 2-alkylanthraquinone content ≥99.5wt%; heteroatom content ≤20ppm; and total metal content ≤20ppm.

40. The method according to claim 39, wherein, The 2-alkylanthraquinone product contains ≥99.5 wt% 2-alkylanthraquinone; ≤15 ppm heteroatom content; and ≤5 ppm total metal content.

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