Method for separating phenylenediamine isomeride

Abstract

The invention provides a method for separating phenylenediamine isomeride. The method provided by the invention comprises the step of carrying out fractional extraction on a raw material solution containing phenylenediamine isomeride by using an extraction agent containing ionic liquid. Compared with a traditional rectification method, the method provided by the invention has the characteristics of low energy consumption, high selectivity, low cost and the like, and is suitable for industrial production.

Description

Technical Field

[0001] This invention belongs to the field of chemical separation technology, specifically relating to a method for separating phenylenediamine isomers. Background Technology

[0002] Phenylenediamine, also known as diaminobenzene, is an important fine chemical raw material and intermediate. It consists of a benzene ring and two amino groups. Based on the position of the amino groups, it can be classified into three isomers: m-phenylenediamine, o-phenylenediamine, and p-phenylenediamine. Phenylenediamine is widely used in the dye, pesticide, synthetic fiber, and rubber industries. o-Phenylenediamine (1,2-phenylenediamine) is a major intermediate in pesticides, pharmaceuticals, dyes, and developing rubber agents. It is used to prepare vat dyes and cationic dyes, and also in the manufacture of polyamides, polyurethanes, and leveling agents. In the pesticide industry, it is used to synthesize systemic fungicides. m-Phenylenediamine (1,3-phenylenediamine) has the highest demand among the isomers. It is an important dye intermediate used to manufacture Basic Orange, Basic Brown G, Direct Fast Black G, and fur dyes. It is also used as a curing agent for epoxy resins, a setting accelerator for cement, and as a mordant and color developer. In the pharmaceutical field, m-phenylenediamine can be used to produce antibacterial drugs. With the development of high-performance polyaromatic amide materials and aramid materials, m-phenylenediamine has broad market prospects in the synthesis of high-temperature resistant and high-strength aramid fibers. p-Phenylenediamine (1,4-phenylenediamine) is an intermediate in azo disperse dyes, acid dyes, direct dyes, and sulfur dyes. It is also an effective component in hair dyes, exhibiting a strong affinity for keratin in hair. Furthermore, it can be used in the production of rubber antioxidants and developers.

[0003]

[0004] Currently, mainstream phenylenediamine production processes, such as the catalytic hydrogenation of a mixture of benzene nitration products and dinitrobenzene, often yield a mixture containing three phenylenediamine isomers. Therefore, it is necessary to separate these isomers to obtain the monomeric compounds. Reported methods for separating phenylenediamine isomers mainly include distillation and crystallization. For example, CN105906512A discloses a single-tower separation process and apparatus for phenylenediamine isomers. This method can achieve continuous separation of the three phenylenediamine isomers in a single main distillation column, but the equipment cost is high, energy consumption is also high, and because phenylenediamine is a heat-sensitive substance, repeated heating easily leads to coking and blackening, producing a large amount of tar, resulting in low product purity and poor quality. CN115304490A discloses a system and method for continuous separation of meta-, para-, and o-phenylenediamines; this system can effectively improve crystal purity and crystallization efficiency, but the separation system is complex to operate, requires high maintenance costs, and requires multiple heating processes during separation, resulting in high energy consumption. Summary of the Invention

[0005] In order to solve one of the above-mentioned technical problems in the prior art, the present invention proposes a method for separating phenylenediamine isomers. By using an extractant containing ionic liquid for fractional extraction, efficient and low-energy separation of the three isomers of phenylenediamine can be achieved.

[0006] The present invention provides a method for separating phenylenediamine isomers, comprising fractionating and extracting a feed liquid containing phenylenediamine isomers using an extractant containing an ionic liquid.

[0007] For phenylenediamine isomers, the amino group of phenylenediamine acts as both a hydrogen bond acceptor (basic hydrogen bond) and a hydrogen bond donor (acidic hydrogen bond). However, the amino substituent positions differ among the three isomers, resulting in varying distances between their hydrogen bond interaction sites with the extractant. Consequently, the strength of the intermolecular hydrogen bond interactions between the extractant and the three phenylenediamine isomers differs. This application creatively discovers that liquid-liquid extraction separation of phenylenediamine isomers can be achieved using ionic liquids by adjusting the differences in the acidity and basicity of the hydrogen bonds in the extractant. The addition of ionic liquids can adjust the partition coefficient of phenylenediamine between the two phases, thereby improving the selectivity coefficient among the three isomers.

[0008] In some embodiments, the cation of the ionic liquid is selected from one or more of imidazole cations, quinoline cations, choline cations, pyridine cations, quaternary ammonium cations, quaternary phosphorus cations, pyrrolidine cations, guanidine cations, amino acid cations, quinine ring cations, benzimidazole cations, benzothiophene cations, and benzofuran cations; optionally, the cation is substituted by one or more substituents selected from alkyl, alkenyl, aryl, cyano, thiocyano, sulfone, carbonyl, and cyanoalkyl. In some specific embodiments, the alkyl group is a C1-C8 (e.g., C1, C2, C3, C4, C5, C6, C7, or C8) straight-chain or branched alkyl group; in some specific embodiments, the alkyl group is a C1-C4 straight-chain alkyl group. In some specific embodiments, the alkenyl group is a C2-C8 (e.g., C2, C3, C4, C5, C6, C7, or C8) alkenyl group; in some specific embodiments, the alkenyl group is a C2-C4 straight-chain alkenyl group. In some embodiments, the aryl group is a C6-C15 aryl group (e.g., C6, C7, C8, C9, C10, C11, C12, C13, C14, or C15); in some embodiments, the aryl group is a phenyl group. In some embodiments, the cyanoalkyl group is a C1-C8 (e.g., C1, C2, C3, C4, C5, C6, C7, or C8) straight-chain or branched alkyl group substituted with a cyano group; in some embodiments, the cyanoalkyl group is a C1-C4 straight-chain alkyl group substituted with a cyano group.

[0009] In some embodiments, the anion of the ionic liquid is selected from one or more of chloride ions, bromide ions, iodide ions, sulfate ions, sulfite ions, sulfonate ions, thiocyanate ions, dicyandiamide ions, tetrafluoroborate ions, tricyanomethane ions, trifluoromethanesulfonate ions, tetracyanoborate ions, hexafluorophosphate ions, nitrate ions, acetate ions, lactate ions, acetylsulimide ions, bis((trifluoromethyl)sulfonyl)imide ions, and amino acid ions.

[0010] In some embodiments, the ionic liquid comprises one or more of the following: 1-ethyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-methylimidazolium hexafluorophosphate, 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium iodide, 1-(butonitrile-3-methylimidazolium)bis((trifluoromethyl)sulfonyl)imide, choline chloride, tributylammonium chloride, 1-hexyl-3-methylimidazolium trifluoromethanesulfonate, 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, and 1-ethyl-3-methylimidazolium dicyandiamide.

[0011] In some preferred embodiments, the ionic liquid comprises one or more of 1-ethyl-3-methylimidazolium hexafluorophosphate, 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium iodide, and 1-(butyronitrile-3-methylimidazolium)bis((trifluoromethyl)sulfonyl)imide.

[0012] In some embodiments, the molar percentage of the ionic liquid, based on the total molar amount of the extractant, is 0.01% to 100%, for example, 0.01%, 0.05%, 0.1%, 0.5%, 1%, 2%, 3%, 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, or 100%. In some specific embodiments, the molar percentage of the ionic liquid, based on the total molar amount of the extractant, is 0.05% to 90%. In some specific embodiments, the molar percentage of the ionic liquid, based on the total molar amount of the extractant, is 0.1% to 10%. In some specific embodiments, the molar percentage of the ionic liquid, based on the total molar amount of the extractant, is 0.5% to 5%.

[0013] In some embodiments, the extractant is selected from at least one of ionic liquids, combinations of ionic liquids and water, and combinations of ionic liquids and organic solvents. In some embodiments, the organic solvent includes one or more of oxygen-containing organic solvents, phosphorus-containing organic solvents, nitrogen-containing organic solvents, and sulfur-containing organic solvents.

[0014] The oxygen-containing organic solvents described in this invention include, but are not limited to, one or more of the following: esters, alcohols, ketones, ethers, and other oxygen-containing organic solvents, such as C2-C10 esters, C4-C10 alcohols, C4-C10 ketones, and C2-C10 ethers. Examples of the oxygen-containing organic solvents described in this invention include, but are not limited to, one or more of the following: methyl acetate, ethyl acetate, propyl acetate, butyl acetate, n-butanol, isobutanol, n-pentanol, isoamyl alcohol, n-hexanol, 2-hexanol, n-heptanol, isooctanol, 2-pentanone, 3-pentanone, cyclohexanone, acetylacetone, methyl isobutyl ketone, diethyl ether, methyl tert-butyl ether, petroleum ether, 1,4-dioxane, etc.

[0015] The phosphorus-containing organic solvents described in this invention include, but are not limited to, one or more of the following: phosphonates, alkylphosphine oxides; examples of phosphorus-containing organic solvents include, but are not limited to, one or more of the following: tributyl phosphate, trioctylphosphine oxide, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, etc.

[0016] The nitrogen-containing organic solvents described in this invention include, but are not limited to, one or more of the following: amides, tertiary amines, quaternary ammonium salts, and other nitrogen-containing organic solvents. Examples of the nitrogen-containing organic solvents described in this invention include, but are not limited to, one or more of the following: N,N-dimethylheptylacetamide, trioctylamine, trioctyldecyl tertiary amine, trialkylmethylamine chloride, etc.

[0017] The sulfur-containing organic solvents described in this invention include, but are not limited to, sulfonic acid organic solvents, such as dodecylbenzenesulfonic acid and dinonylnaphthalenesulfonic acid.

[0018] In some embodiments, the extractant includes ionic liquids and water.

[0019] In some embodiments, the extractant comprises an ionic liquid and a combination of one or more organic solvents selected from methyl acetate, ethyl acetate, butyl acetate, n-butanol, isobutanol, n-hexanol, n-octanol, methyl tert-butyl ether, 2-pentanone, 3-pentanone, cyclohexanone, acetylacetone, and 1,4-dioxane.

[0020] In some embodiments, the extractant is selected from at least one of ionic liquids, combinations of ionic liquids and water, combinations of ionic liquids and n-butanol, and combinations of ionic liquids and ethyl acetate.

[0021] In some specific embodiments, the extractant is an ionic liquid.

[0022] In some specific embodiments, the extractant is selected from at least one of the following: a combination of 1-ethyl-3-methylimidazolium hexafluorophosphate and ethyl acetate; a combination of 1-ethyl-3-methylimidazolium hexafluorophosphate and n-butanol; 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide; 1-ethyl-3-methylimidazolium tetrafluoroborate; a combination of 1-ethyl-3-methylimidazolium iodide and water; and a combination of 1-(butyronitrile-3-methylimidazolium)bis((trifluoromethyl)sulfonyl)imide and ethyl acetate.

[0023] The phenylenediamine isomers described in this application include any two or three of o-phenylenediamine, m-phenylenediamine, and p-phenylenediamine. In some specific embodiments, the phenylenediamine isomers are mixtures of o-phenylenediamine, m-phenylenediamine, and p-phenylenediamine.

[0024] In some embodiments, the mass ratio of o-phenylenediamine to p-phenylenediamine in the feed solution is (1 to 10):1, for example, 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1 or any value between them.

[0025] In some embodiments, the mass ratio of intermediate-phenylenediamine to p-phenylenediamine in the feed liquid is (10-50):1, for example, 10:1, 15:1, 20:1, 25:1, 30:1, 35:1, 40:1, 45:1, 50:1 or any value between them.

[0026] In some embodiments, the mass ratio of o-phenylenediamine to m-phenylenediamine in the feed solution is (0.02 to 1):1, for example, 0.02:1, 0.05:1, 0.1:1, 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1 or any value between them.

[0027] In some embodiments, the feed liquid further includes a feed solvent. The feed solvent described in this application is immiscible or only slightly soluble with the extractant. In some embodiments, the solubility of the feed solvent in the extractant is less than 15 g. In some embodiments, the solubility of the feed solvent in the extractant is less than 10 g. In some embodiments, the solubility of the feed solvent in the extractant is less than 5 g. In some embodiments, the solubility of the feed solvent in the extractant is less than 1 g.

[0028] The raw material solvent and the detergent used in the fractional extraction may be the same or different. In some embodiments, the raw material solvent and the detergent used in the fractional extraction are the same. In some embodiments, the raw material solvent and the detergent used in the fractional extraction are each independently selected from water, C2-C10 ester solvents, C2-C10 alcohol solvents, or C2-C10 ketone solvents. In some specific embodiments, the raw material solvent and the detergent used in the fractional extraction are each independently selected from at least one of water, methyl acetate, ethyl acetate, butyl acetate, n-butanol, isobutanol, n-pentanol, isopentanol, n-hexanol, 2-hexanol, n-heptanol, isooctanol, hexanone, and cyclohexanone. In some embodiments, both the raw material solvent and the detergent used in the fractional extraction are water. In some embodiments, both the raw material solvent and the detergent used in the fractional extraction are ethyl acetate.

[0029] In some embodiments, the flow ratio of the extractant to the feed liquid in the fractionation extraction is (1–15):1, for example, 1:1, 2:1, 5:1, 8:1, 10:1, 12:1, 15:1, or any value between them. In some embodiments, the flow ratio of the extractant to the feed liquid is (5–10):1.

[0030] In some embodiments, during the fractionation extraction, the flow ratio of the detergent to the feed liquid is (0.1–10):1, for example, 0.1:1, 1:1, 2:1, 3:1, 5:1, 8:1, 10:1, or any value between them. In some embodiments, the flow ratio of the detergent to the feed liquid is (1–5):1.

[0031] When performing fractional extraction, taking into account factors such as product quality and production cost, the flow ratio of the extractant, detergent and raw material liquid is (1-15):(0.1-10):1, preferably (5-10):(1-5):1.

[0032] Considering both the throughput of the extraction system and the solubility of phenylenediamine, the total concentration of phenylenediamine isomers in the feed solution of this invention is 0.1 g / L to 200.0 g / L, for example, 0.1 g / L, 1 g / L, 5 g / L, 10 g / L, 20 g / L, 40 g / L, 60 g / L, 80 g / L, 100 g / L, 120 g / L, 140 g / L, 160 g / L, 180 g / L, 200 g / L, or any value between them. In some embodiments, the total concentration of phenylenediamine isomers in the feed solution is 0.1 g / L to 100.0 g / L. In some embodiments, the total concentration of phenylenediamine isomers in the feed solution is 1 g / L to 50.0 g / L. In some embodiments, the total concentration of phenylenediamine isomers in the feed solution is 1 g / L to 20.0 g / L. Too high a concentration may exceed the solubility range of phenylenediamine, while too low a concentration will greatly reduce the processing capacity, decrease efficiency, and increase costs.

[0033] In some embodiments, the fractionation extraction temperature is 20–70°C, for example, 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, or any value between them. If the extraction temperature is too low, the solution viscosity is high, which is detrimental to mixing and mass transfer, reducing separation efficiency; if the extraction temperature is too high, the organic solvent will begin to evaporate, which will not only affect the extraction effect but may also cause pollution.

[0034] In some embodiments, the fractionation extraction time is from 5 min to 200 min, for example, 5 min, 10 min, 30 min, 60 min, 90 min, 120 min, 150 min, 180 min, 200 min, or any value between them. Too short an extraction time will result in insufficient contact between the extractant and the feed liquid, incomplete extraction, and a decrease in the extraction yield; too long an extraction time will cause unnecessary consumption and increase costs.

[0035] In some implementations, the method includes the following steps:

[0036] The phenylenediamine isomer is mixed with the raw material solvent to obtain a raw material solution;

[0037] The feed liquid is subjected to a first fractional extraction using the ionic liquid-containing extractant to obtain a first extract and a first raffinate.

[0038] In this invention, when the feed solution contains o-phenylenediamine, the first extract contains o-phenylenediamine, and the first raffinate contains m-phenylenediamine and / or p-phenylenediamine; for example, when the feed solution contains three isomers of o-phenylenediamine, m-phenylenediamine, and p-phenylenediamine, the first extract contains o-phenylenediamine, and the first raffinate contains m-phenylenediamine and p-phenylenediamine; when the feed solution contains two isomers of o-phenylenediamine and m-phenylenediamine, the first extract contains o-phenylenediamine, and the first raffinate contains m-phenylenediamine; when the feed solution contains two isomers of o-phenylenediamine and p-phenylenediamine, the first extract contains o-phenylenediamine, and the first raffinate contains p-phenylenediamine.

[0039] In this invention, when the raw material solution does not contain o-phenylenediamine (i.e., the raw material solution contains two isomers, m-phenylenediamine and p-phenylenediamine), the first extract contains m-phenylenediamine, and the first raffinate contains p-phenylenediamine.

[0040] In some specific embodiments, the method further includes the steps of concentrating, washing, and drying the first extract.

[0041] In some specific embodiments, the method further includes the steps of concentrating, washing, and drying the first raffinate.

[0042] In some specific embodiments, the method further includes the step of performing a second fractionation extraction treatment on the first raffinate using the ionic liquid-containing extractant to obtain a second extract and a second raffinate.

[0043] In this invention, when the raw material liquid contains three isomers, namely o-phenylenediamine, m-phenylenediamine and p-phenylenediamine, the first raffinate obtained contains two isomers, m-phenylenediamine and p-phenylenediamine. Therefore, the first raffinate obtained needs to undergo a second fractional extraction. The second extract obtained from the second fractional extraction contains m-phenylenediamine, and the second raffinate contains p-phenylenediamine.

[0044] In some specific embodiments, the method further includes the steps of concentrating, washing, and drying the second extract.

[0045] In some specific embodiments, the method further includes the steps of concentrating, washing, and drying the second raffinate.

[0046] In some implementations, the method includes the following steps:

[0047] The mixture of phenylenediamine isomers is mixed with a raw material solvent to obtain a raw material solution;

[0048] The feed liquid is subjected to a first-stage fractional extraction using the ionic liquid-containing extractant to obtain an extract containing o-phenylenediamine and a raffinate containing m-phenylenediamine and / or p-phenylenediamine.

[0049] In some specific embodiments, the method further includes: concentrating, washing, and drying the o-phenylenediamine-containing extract to obtain o-phenylenediamine. In some specific embodiments, the method further includes the following steps: concentrating, washing, and drying the m-phenylenediamine-containing raffinate to obtain m-phenylenediamine; or, concentrating, washing, and drying the p-phenylenediamine-containing raffinate to obtain p-phenylenediamine; or, performing a second-stage fractional extraction on the raffinates containing m-phenylenediamine and p-phenylenediamine using the ionic liquid-containing extractant; to obtain an extract containing m-phenylenediamine and a raffinate containing p-phenylenediamine. In some specific embodiments, the method further includes: concentrating, washing, and drying the m-phenylenediamine-containing extract to obtain m-phenylenediamine. In some specific embodiments, the method further includes: concentrating, washing, and drying the p-phenylenediamine-containing raffinate to obtain p-phenylenediamine.

[0050] In some embodiments, the fractionation extraction of the present invention is a multi-stage (e.g., 3 to 10 stages) fractionation extraction. In some embodiments, the fractionation extraction has 5 to 10 extraction stages. In some embodiments, the fractionation extraction has 3 to 6 washing stages.

[0051] Compared with the prior art, the present invention has the following beneficial effects:

[0052] 1. The fractionation extraction process used in this invention has advantages over distillation processes, such as low energy consumption, low cost, and ease of operation, and the cost of the selected organic solvents is also lower.

[0053] 2. The present invention selects an extractant containing ionic liquid, especially a mixed extractant composed of ionic liquid and water or ionic liquid and organic solvent, to separate and extract phenylenediamine isomers. Compared with using organic solvent alone as an extractant, this can significantly improve the selectivity of extraction and improve the separation efficiency.

[0054] 3. The extractant used in this invention can be recycled and reused after back-extraction and concentration. Attached Figure Description

[0055] Figure 1 This is a schematic diagram of the fractionation and extraction equipment used in the process of separating phenylenediamine isomers according to a specific embodiment of the present invention.

[0056] Figure 2This is a process flow diagram for separating phenylenediamine isomers according to an embodiment of the present invention, wherein: 1-first extraction tower, 2-o-phenylenediamine extract storage tank, 3-second extraction tower, 4-m-phenylenediamine extract storage tank, and 5-p-phenylenediamine raffinate storage tank. Detailed Implementation

[0057] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments and accompanying drawings. The specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the invention in any way.

[0058] the term

[0059] The "fractional extraction" described in this application refers to a cascade extraction process in which the feed liquid (F) containing the components to be separated flows into the middle stage of a cascade extractor, while the wash liquid (W) and organic phase (S) without the components to be separated flow into the two ends of the cascade extractor, respectively. Compared with distillation, fractional extraction has the advantages of low energy consumption and high selectivity.

[0060] According to some specific embodiments of the present invention, such as Figure 1 As shown, the fractional extraction equipment used in the process comprises two stages, each consisting of an extraction stage and a washing stage. First, a first-stage fractional extraction process is employed to separate high-purity o-phenylenediamine. The extractant enters the fractional extraction system from the first stage of the extraction stage, the feed liquid enters from the last stage of the extraction stage, and the washing agent enters from the first stage of the washing stage. At the last stage of the extraction stage, the feed liquid and washing phase are combined and enter the extraction stage together. The extract and washing phases undergo multi-stage countercurrent contact. A raffinate enriched with m-phenylenediamine and p-phenylenediamine flows out from the first stage of the extraction stage, and this raffinate is collected. An extract enriched with o-phenylenediamine flows out from the first stage of the washing stage. The raffinate from the first-stage fractional extraction serves as the feed liquid for the second-stage fractional extraction, entering the fractional extraction system from the last stage of the extraction stage. The remaining operations are the same as the first stage. An extract enriched with m-phenylenediamine flows out from the first stage of the washing stage, and a raffinate enriched with p-phenylenediamine flows out from the first stage of the extraction stage. Figure 1 In the diagram, 1 to n represent the first to nth segments of the extraction section, and 1' to n' represent the first to n'th segments of the washing section. The purity of the phenylenediamine isomers obtained by the optimized separation method of this invention is: absolute purity > 90 wt%; purity of each isomer > 95 wt%.

[0061] In the following examples and comparative examples, the concentrations of phenylenediamine isomers were analyzed by high-performance liquid chromatography (HPLC). The specific HPLC analytical conditions were as follows: a Waters Sunfire C18 column (4.6 mm ID × 250 mm, particle size 5 μm); a mobile phase of methanol (20 vol.%) aqueous solution; the addition of 0.1% triethylamine to suppress peak tailing; and adjustment of the pH to 7 with dilute acid. The flow rate was 1 mL / min, the column temperature was 30 °C, and the UV detector wavelength was set to 240 nm. The retention times of the three isomers were: p-phenylenediamine 4.3 ± 0.1 min, m-phenylenediamine 5.8 ± 0.1 min, and o-phenylenediamine 9.6 ± 0.1 min.

[0062] In the following examples and comparative examples, the methods for calculating yield and purity are as follows:

[0063] o-Phenylenediamine yield = (mass of o-phenylenediamine in product / mass of o-phenylenediamine in feed) × 100%;

[0064] m-Phenylated diamine yield = mass of intermediate-phenylenediamine / mass of o-phenylenediamine in raw materials × 100%;

[0065] p-Phenylenediamine yield = (mass of p-phenylenediamine in the product / mass of o-phenylenediamine in the feedstock) × 100%;

[0066] Purity of o-phenylenediamine = (mass of o-phenylenediamine in the product / total mass of the product) × 100%;

[0067] Purity of m-phenylenediamine = Mass of intermediate-phenylenediamine / Total mass of product × 100%;

[0068] Purity of p-phenylenediamine = mass of p-phenylenediamine in the product / total mass of the product × 100%.

[0069] like Figure 2 As shown, the process flow for separating m-phenylenediamine, o-phenylenediamine, and p-phenylenediamine in the following embodiments of the present invention is as follows: the raw materials containing m-phenylenediamine, o-phenylenediamine, and p-phenylenediamine are fed into the first extraction tower for fractional extraction to obtain an extract containing o-phenylenediamine and a raffinate containing m-phenylenediamine and p-phenylenediamine. The extract containing o-phenylenediamine is post-treated to obtain o-phenylenediamine. The raffinate containing m-phenylenediamine and p-phenylenediamine is fed into the second extraction tower for fractional extraction to obtain an extract containing m-phenylenediamine and a raffinate containing p-phenylenediamine. The extract containing m-phenylenediamine is post-treated to obtain m-phenylenediamine, and the raffinate containing p-phenylenediamine is post-treated to obtain p-phenylenediamine.

[0070] Example 1

[0071] A mixture of m-phenylenediamine, o-phenylenediamine, and p-phenylenediamine (with m-phenylenediamine comprising 90% by mass, o-phenylenediamine 8% by mass, and p-phenylenediamine 2% by mass) was dissolved in water to prepare a feed solution with a total concentration of 5 g / L. A mixed solvent of 1-ethyl-3-methylimidazolium hexafluorophosphate and ethyl acetate was used as the extractant (1% by molar fraction of 1-ethyl-3-methylimidazolium hexafluorophosphate), and water was used as the washing agent. The flow ratio of extractant, washing agent, and feed solution in the first stage of fractional extraction was 5:5:1, and fractional extraction was carried out at 30°C. The extraction stage consisted of 10 stages, and the washing stage consisted of 6 stages. The extractant entered the fractional extraction system from the first stage of the extraction stage, the feed solution entered from the last stage of the extraction stage, and the washing agent entered from the first stage of the washing stage. The first stage of the washing section produces an extract rich in o-phenylenediamine, while the first stage of the extraction section produces a raffinate rich in m-phenylenediamine and p-phenylenediamine. The extract and raffinate are collected.

[0072] The raffinate from the first stage of fractional extraction serves as the feed for the second stage, entering the fractional extraction system from the last stage of the extraction section. The flow ratio of extractant, washing agent, and feed for the second stage is 10:1:1. Fractional extraction is carried out at 30°C, consisting of 6 stages in the extraction section and 3 stages in the washing section. The remaining operations are the same as the first stage. The extract rich in m-phenylenediamine flows out from the first stage of the washing section, and the raffinate rich in p-phenylenediamine flows out from the first stage of the extraction section. Both the extract and the raffinate are collected.

[0073] The extract and raffinate were concentrated under vacuum, washed with water, and dried to obtain o-phenylenediamine, m-phenylenediamine, and p-phenylenediamine. The purity of o-phenylenediamine was 99.72%, with a yield of 96.35%; the purity of m-phenylenediamine was 99.51%, with a yield of 97.54%; and the purity of p-phenylenediamine was 98.39%, with a yield of 97.36%.

[0074] Example 2

[0075] A mixture of m-phenylenediamine, o-phenylenediamine, and p-phenylenediamine (with m-phenylenediamine comprising 90% by mass, o-phenylenediamine 8% by mass, and p-phenylenediamine 2% by mass) was dissolved in water to prepare a feed solution with a total concentration of 5 g / L. A mixed solvent of 1-ethyl-3-methylimidazolium hexafluorophosphate and ethyl acetate was used as the extractant (1% by molar fraction of 1-ethyl-3-methylimidazolium hexafluorophosphate), and water was used as the washing agent. The flow ratio of extractant, washing agent, and feed solution in the first stage of fractional extraction was 10:5:1, and fractional extraction was carried out at 30°C. The extraction stage consisted of 10 stages, and the washing stage consisted of 6 stages. The extractant entered the fractional extraction system from the first stage of the extraction stage, the feed solution entered from the last stage of the extraction stage, and the washing agent entered from the first stage of the washing stage. The first stage of the washing section produces an extract rich in o-phenylenediamine, while the first stage of the extraction section produces a raffinate rich in m-phenylenediamine and p-phenylenediamine. The extract and raffinate are collected.

[0076] The raffinate from the first stage of fractional extraction serves as the feed for the second stage, entering the fractional extraction system from the last stage of the extraction section. The flow ratio of extractant, washing agent, and feed for the second stage is 10:1:1. Fractional extraction is carried out at 30°C, consisting of 6 stages in the extraction section and 3 stages in the washing section. The remaining operations are the same as the first stage. The extract rich in m-phenylenediamine flows out from the first stage of the washing section, and the raffinate rich in p-phenylenediamine flows out from the first stage of the extraction section. Both the extract and the raffinate are collected.

[0077] The extract and raffinate were concentrated under vacuum, washed with water, and dried to obtain o-phenylenediamine, m-phenylenediamine, and p-phenylenediamine. The purity of o-phenylenediamine was 99.54%, with a yield of 98.49%; the purity of m-phenylenediamine was 99.51%, with a yield of 97.31%; and the purity of m-phenylenediamine was 99.24%, with a yield of 96.24%.

[0078] Example 3

[0079] A mixture of m-phenylenediamine, o-phenylenediamine, and p-phenylenediamine (with m-phenylenediamine comprising 90% by mass, o-phenylenediamine 8% by mass, and p-phenylenediamine 2% by mass) was dissolved in water to prepare a feed solution with a total concentration of 5 g / L. A mixed solvent of 1-ethyl-3-methylimidazolium hexafluorophosphate and n-butanol was used as the extractant (1% by molar fraction of 1-ethyl-3-methylimidazolium hexafluorophosphate), and water was used as the washing agent. The flow ratio of extractant, washing agent, and feed solution in the first stage of fractional extraction was 5:5:1, and fractional extraction was carried out at 30°C. The extraction stage consisted of 10 stages, and the washing stage consisted of 6 stages. The extractant entered the fractional extraction system from the first stage of the extraction stage, the feed solution entered from the last stage of the extraction stage, and the washing agent entered from the first stage of the washing stage. The first stage of the washing section produces an extract rich in o-phenylenediamine, while the first stage of the extraction section produces a raffinate rich in m-phenylenediamine and p-phenylenediamine. The extract and raffinate are collected.

[0080] The raffinate from the first stage of fractional extraction serves as the feed for the second stage, entering the fractional extraction system from the last stage of the extraction section. The flow ratio of extractant, washing agent, and feed for the second stage is 10:1:1. Fractional extraction is carried out at 30°C, consisting of 6 stages in the extraction section and 3 stages in the washing section. The remaining operations are the same as the first stage. The extract rich in m-phenylenediamine flows out from the first stage of the washing section, and the raffinate rich in p-phenylenediamine flows out from the first stage of the extraction section. Both the extract and the raffinate are collected.

[0081] The extract and raffinate were concentrated under vacuum, washed with water, and dried to obtain o-phenylenediamine, m-phenylenediamine, and p-phenylenediamine. The purity of o-phenylenediamine was 99.78%, with a yield of 96.25%; the purity of m-phenylenediamine was 99.65%, with a yield of 98.24%; and the purity of p-phenylenediamine was 99.46%, with a yield of 95.48%.

[0082] Example 4

[0083] A mixture of m-phenylenediamine, o-phenylenediamine, and p-phenylenediamine (with m-phenylenediamine comprising 90% by mass, o-phenylenediamine 8% by mass, and p-phenylenediamine 2% by mass) was dissolved in water to prepare a feed solution with a total concentration of 5 g / L. A mixed solvent of 1-ethyl-3-methylimidazolium hexafluorophosphate and ethyl acetate was used as the extractant (1% by molar fraction of 1-ethyl-3-methylimidazolium hexafluorophosphate), and water was used as the washing agent. The flow ratio of extractant, washing agent, and feed solution in the first stage of fractional extraction was 5:5:1, and fractional extraction was carried out at 25°C. The extraction stage consisted of 10 stages, and the washing stage consisted of 6 stages. The extractant entered the fractional extraction system from the first stage of the extraction stage, the feed solution entered from the last stage of the extraction stage, and the washing agent entered from the first stage of the washing stage. The first stage of the washing section produces an extract rich in o-phenylenediamine, while the first stage of the extraction section produces a raffinate rich in m-phenylenediamine and p-phenylenediamine. The extract and raffinate are collected.

[0084] The raffinate from the first stage of fractional extraction serves as the feed for the second stage, entering the fractional extraction system from the last stage of the extraction section. The flow ratio of extractant, washing agent, and feed for the second stage is 10:1:1. Fractional extraction is carried out at 30°C, consisting of 6 stages in the extraction section and 3 stages in the washing section. The remaining operations are the same as the first stage. The extract rich in m-phenylenediamine flows out from the first stage of the washing section, and the raffinate rich in p-phenylenediamine flows out from the first stage of the extraction section. Both the extract and the raffinate are collected.

[0085] The extract and raffinate were concentrated under vacuum, washed with water, and dried to obtain o-phenylenediamine, m-phenylenediamine, and p-phenylenediamine. The purity of o-phenylenediamine was 99.98%, with a yield of 98.64%; the purity of m-phenylenediamine was 99.56%, with a yield of 95.13%; and the purity of p-phenylenediamine was 99.56%, with a yield of 96.35%.

[0086] Example 5

[0087] A mixture of m-phenylenediamine, o-phenylenediamine, and p-phenylenediamine (with m-phenylenediamine comprising 90% by mass, o-phenylenediamine 8% by mass, and p-phenylenediamine 2% by mass) was dissolved in water to prepare a feed solution with a total concentration of 5 g / L. A mixed solvent of 1-ethyl-3-methylimidazolium hexafluorophosphate and ethyl acetate was used as the extractant (1-ethyl-3-methylimidazolium hexafluorophosphate molar fraction 5%), and water was used as the washing agent. The flow ratio of extractant, washing agent, and feed solution in the first stage of fractional extraction was 5:5:1, and fractional extraction was carried out at 30°C. The extraction stage consisted of 10 stages, and the washing stage consisted of 6 stages. The extractant entered the fractional extraction system from the first stage of the extraction stage, the feed solution entered from the last stage of the extraction stage, and the washing agent entered from the first stage of the washing stage. The first stage of the washing section produces an extract rich in o-phenylenediamine, while the first stage of the extraction section produces a raffinate rich in m-phenylenediamine and p-phenylenediamine. The extract and raffinate are collected.

[0088] The raffinate from the first stage of fractional extraction serves as the feed for the second stage, entering the fractional extraction system from the last stage of the extraction section. The flow ratio of extractant, washing agent, and feed for the second stage is 10:1:1. Fractional extraction is carried out at 30°C, consisting of 6 stages in the extraction section and 3 stages in the washing section. The remaining operations are the same as the first stage. The extract rich in m-phenylenediamine flows out from the first stage of the washing section, and the raffinate rich in p-phenylenediamine flows out from the first stage of the extraction section. Both the extract and the raffinate are collected.

[0089] The extract and raffinate were concentrated under vacuum, washed with water, and dried to obtain o-phenylenediamine, m-phenylenediamine, and p-phenylenediamine. The purity of o-phenylenediamine was 99.64%, with a yield of 97.25%; the purity of m-phenylenediamine was 99.08%, with a yield of 96.34%; and the purity of p-phenylenediamine was 99.16%, with a yield of 97.69%.

[0090] Example 6

[0091] A mixture of m-phenylenediamine, o-phenylenediamine, and p-phenylenediamine (with m-phenylenediamine comprising 90% by mass, o-phenylenediamine 8% by mass, and p-phenylenediamine 2% by mass) was dissolved in water to prepare a feed solution with a total concentration of 20 g / L. A mixed solvent of 1-ethyl-3-methylimidazolium hexafluorophosphate and ethyl acetate was used as the extractant (1% by molar fraction of 1-ethyl-3-methylimidazolium hexafluorophosphate), and water was used as the washing agent. The flow ratio of extractant, washing agent, and feed solution in the first stage of fractional extraction was 5:5:1, and fractional extraction was carried out at 30°C. The extraction stage consisted of 5 stages, and the washing stage also consisted of 5 stages. The extractant entered the fractional extraction system from the first stage of the extraction stage, the feed solution entered from the last stage of the extraction stage, and the washing agent entered from the first stage of the washing stage. The first stage of the washing section produces an extract rich in o-phenylenediamine, while the first stage of the extraction section produces a raffinate rich in m-phenylenediamine and p-phenylenediamine. The extract and raffinate are collected.

[0092] The raffinate from the first stage of fractional extraction serves as the feed for the second stage, entering the fractional extraction system from the last stage of the extraction section. The flow ratio of extractant, washing agent, and feed for the second stage is 10:1:1. Fractional extraction is carried out at 30°C, consisting of 6 stages in the extraction section and 3 stages in the washing section. The remaining operations are the same as the first stage. The extract rich in m-phenylenediamine flows out from the first stage of the washing section, and the raffinate rich in p-phenylenediamine flows out from the first stage of the extraction section. Both the extract and the raffinate are collected.

[0093] The extract and raffinate were concentrated under vacuum, washed with water, and dried to obtain o-phenylenediamine, m-phenylenediamine, and p-phenylenediamine. The purity of o-phenylenediamine was 99.70%, with a yield of 96.31%; the purity of m-phenylenediamine was 99.23%, with a yield of 97.02%; and the purity of p-phenylenediamine was 98.12%, with a yield of 97.06%.

[0094] Example 7

[0095] A mixture of m-phenylenediamine, o-phenylenediamine, and p-phenylenediamine (with m-phenylenediamine comprising 90% by mass, o-phenylenediamine 8% by mass, and p-phenylenediamine 2% by mass) was dissolved in water to prepare a feed solution with a total concentration of 5 g / L. A mixed solvent of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt and ethyl acetate was used as the extractant (1% by molar fraction of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt), and water was used as the washing agent. The flow ratio of extractant, washing agent, and feed solution in the first stage of fractional extraction was 5:5:1, and fractional extraction was carried out at 30°C. The extraction stage consisted of 10 stages, and the washing stage consisted of 6 stages. The extractant entered the fractional extraction system from the first stage of the extraction stage, the feed solution entered from the last stage of the extraction stage, and the washing agent entered from the first stage of the washing stage. The first stage of the washing section produces an extract rich in o-phenylenediamine, while the first stage of the extraction section produces a raffinate rich in m-phenylenediamine and p-phenylenediamine. The extract and raffinate are collected.

[0096] The raffinate from the first stage of fractional extraction serves as the feed for the second stage, entering the fractional extraction system from the last stage of the extraction section. The flow ratio of extractant, washing agent, and feed for the second stage is 10:1:1. Fractional extraction is carried out at 30°C, consisting of 6 stages in the extraction section and 3 stages in the washing section. The remaining operations are the same as the first stage. The extract rich in m-phenylenediamine flows out from the first stage of the washing section, and the raffinate rich in p-phenylenediamine flows out from the first stage of the extraction section. Both the extract and the raffinate are collected.

[0097] The extract and raffinate were concentrated under vacuum, washed with water, and dried to obtain o-phenylenediamine, m-phenylenediamine, and p-phenylenediamine. The purity of o-phenylenediamine was 99.14%, with a yield of 95.97%; the purity of m-phenylenediamine was 99.26%, with a yield of 996.32%; and the purity of p-phenylenediamine was 98.46%, with a yield of 96.99%.

[0098] Example 8

[0099] A mixture of m-phenylenediamine, o-phenylenediamine, and p-phenylenediamine (with m-phenylenediamine comprising 90% by mass, o-phenylenediamine 8% by mass, and p-phenylenediamine 2% by mass) was dissolved in ethyl acetate to prepare a feed solution with a total concentration of 5 g / L. 1-Ethyl-3-methylimidazolium tetrafluoroborate was used as the extractant and ethyl acetate as the washing agent. The flow ratio of extractant, washing agent, and feed solution in the first fractionation extraction stage was 5:5:1, and fractionation extraction was carried out at 30°C. The extraction stage consisted of 10 stages, and the washing stage consisted of 6 stages. The extractant entered the fractionation extraction system from the first stage of the extraction stage, the feed solution entered from the last stage of the extraction stage, and the washing agent entered from the first stage of the washing stage. An extract rich in o-phenylenediamine flowed out from the first stage of the washing stage, and a raffinate rich in m-phenylenediamine and p-phenylenediamine flowed out from the first stage of the extraction stage. Both the extract and the raffinate were collected.

[0100] The raffinate from the first stage of fractional extraction serves as the feed for the second stage, entering the fractional extraction system from the last stage of the extraction section. The flow ratio of extractant, washing agent, and feed for the second stage is 10:2:1. Fractional extraction is carried out at 30°C, consisting of 6 stages in the extraction section and 3 stages in the washing section. The remaining operations are the same as the first stage. The extract rich in m-phenylenediamine flows out from the first stage of the washing section, and the raffinate rich in p-phenylenediamine flows out from the first stage of the extraction section. Both the extract and the raffinate are collected.

[0101] The extract and raffinate were concentrated under vacuum, washed with water, and dried to obtain o-phenylenediamine, m-phenylenediamine, and p-phenylenediamine. The purity of o-phenylenediamine was 95.16%, with a yield of 96.14%; the purity of m-phenylenediamine was 96.35%, with a yield of 97.20%; and the purity of p-phenylenediamine was 95.47%, with a yield of 96.34%.

[0102] Example 9

[0103] A mixture of m-phenylenediamine, o-phenylenediamine, and p-phenylenediamine (with m-phenylenediamine comprising 90% by mass, o-phenylenediamine 8% by mass, and p-phenylenediamine 2% by mass) was dissolved in ethyl acetate to prepare a feed solution with a total concentration of 5 g / L. A 1-ethyl-3-methylimidazolium iodide-water mixture was used as the extractant (1% by molar fraction of 1-ethyl-3-methylimidazolium iodide) and ethyl acetate as the washing agent. The flow ratio of extractant, washing agent, and feed solution in the first fractionation extraction stage was 5:5:1, and fractionation extraction was carried out at 30°C. The extraction stage consisted of 10 stages, and the washing stage consisted of 6 stages. The extractant entered the fractionation extraction system from the first stage of the extraction stage, the feed solution entered from the last stage of the extraction stage, and the washing agent entered from the first stage of the washing stage. The first stage of the washing section produces an extract rich in o-phenylenediamine, while the first stage of the extraction section produces a raffinate rich in m-phenylenediamine and p-phenylenediamine. The extract and raffinate are collected.

[0104] The raffinate from the first stage of fractional extraction serves as the feed for the second stage, entering the fractional extraction system from the last stage of the extraction section. The flow ratio of extractant, washing agent, and feed for the second stage is 10:2:1. Fractional extraction is carried out at 30°C, consisting of 6 stages in the extraction section and 3 stages in the washing section. The remaining operations are the same as the first stage. The extract rich in m-phenylenediamine flows out from the first stage of the washing section, and the raffinate rich in p-phenylenediamine flows out from the first stage of the extraction section. Both the extract and the raffinate are collected.

[0105] The extract and raffinate were concentrated under vacuum, washed with water, and dried to obtain o-phenylenediamine, m-phenylenediamine, and p-phenylenediamine. The purity of o-phenylenediamine was 99.52%, with a yield of 98.63%; the purity of m-phenylenediamine was 99.74%, with a yield of 98.97%; and the purity of p-phenylenediamine was 99.51%, with a yield of 98.88%.

[0106] Example 10

[0107] A mixture of m-phenylenediamine, o-phenylenediamine, and p-phenylenediamine (with m-phenylenediamine comprising 90% by mass, o-phenylenediamine 8% by mass, and p-phenylenediamine 2% by mass) was dissolved in water to prepare a feed solution with a total concentration of 5 g / L. A mixed solvent of 1-(butyronitrile-3-methylimidazolium)bis((trifluoromethyl)sulfonyl)imide and ethyl acetate was used as the extractant (1% by molar fraction of 1-(butyronitrile-3-methylimidazolium)bis((trifluoromethyl)sulfonyl)imide), and water was used as the washing agent. The flow ratio of extractant, washing agent, and feed solution in the first stage of fractional extraction was 5:5:1, and fractional extraction was carried out at 30°C. The extraction stage consisted of 10 stages, and the washing stage consisted of 6 stages. The extractant entered the fractional extraction system from the first stage of the extraction stage, the feed solution entered from the last stage of the extraction stage, and the washing agent entered from the first stage of the washing stage. The first stage of the washing section produces an extract rich in o-phenylenediamine, while the first stage of the extraction section produces a raffinate rich in m-phenylenediamine and p-phenylenediamine. The extract and raffinate are collected.

[0108] The raffinate from the first stage of fractional extraction serves as the feed for the second stage, entering the fractional extraction system from the last stage of the extraction section. The flow ratio of extractant, washing agent, and feed for the second stage is 10:2:1. Fractional extraction is carried out at 30°C, consisting of 6 stages in the extraction section and 3 stages in the washing section. The remaining operations are the same as the first stage. The extract rich in m-phenylenediamine flows out from the first stage of the washing section, and the raffinate rich in p-phenylenediamine flows out from the first stage of the extraction section. Both the extract and the raffinate are collected.

[0109] The extract and raffinate were concentrated under vacuum, washed with water, and dried to obtain o-phenylenediamine, m-phenylenediamine, and p-phenylenediamine. The purity of o-phenylenediamine was 98.13%, with a yield of 99.64%; the purity of m-phenylenediamine was 97.11%, with a yield of 98.95%; and the purity of p-phenylenediamine was 99.34%, with a yield of 98.67%.

[0110] Example 11

[0111] A mixture of m-phenylenediamine, o-phenylenediamine, and p-phenylenediamine (with m-phenylenediamine comprising 90% by mass, o-phenylenediamine 8% by mass, and p-phenylenediamine 2% by mass) was dissolved in water to prepare a feed solution with a total concentration of 5 g / L. A mixed solvent of 1-ethyl-3-methylimidazolium hexafluorophosphate and ethyl acetate was used as the extractant (1% by molar fraction of 1-ethyl-3-methylimidazolium hexafluorophosphate), and water was used as the washing agent. The flow ratio of extractant, washing agent, and feed solution in the first stage of fractional extraction was 5:5:1, and fractional extraction was carried out at 30°C. The extraction stage consisted of 10 stages, and the washing stage consisted of 6 stages. The extractant entered the fractional extraction system from the first stage of the extraction stage, the feed solution entered from the last stage of the extraction stage, and the washing agent entered from the first stage of the washing stage. The first stage of the washing section produces an extract rich in o-phenylenediamine, while the first stage of the extraction section produces a raffinate rich in m-phenylenediamine and p-phenylenediamine. The extract and raffinate are collected.

[0112] The raffinate from the first stage of fractional extraction serves as the feed for the second stage, entering the fractional extraction system from the last stage of the extraction section. The flow ratio of extractant, washing agent, and feed for the second stage is 10:2:1. Fractional extraction is carried out at 30°C, consisting of 6 stages in the extraction section and 3 stages in the washing section. The remaining operations are the same as the first stage. The extract rich in m-phenylenediamine flows out from the first stage of the washing section, and the raffinate rich in p-phenylenediamine flows out from the first stage of the extraction section. Both the extract and the raffinate are collected.

[0113] The extract and raffinate were concentrated under vacuum, washed with water, and dried to obtain o-phenylenediamine, m-phenylenediamine, and p-phenylenediamine. The purity of o-phenylenediamine was 99.27%, with a yield of 97.97%; the purity of m-phenylenediamine was 99.66%, with a yield of 98.11%; and the purity of p-phenylenediamine was 97.46%, with a yield of 98.33%.

[0114] Example 12

[0115] A mixture of m-phenylenediamine, o-phenylenediamine, and p-phenylenediamine (with m-phenylenediamine comprising 90% by mass, o-phenylenediamine 8% by mass, and p-phenylenediamine 2% by mass) was dissolved in water to prepare a feed solution with a total concentration of 5 g / L. A mixed solvent of 1-ethyl-3-methylimidazolium hexafluorophosphate and ethyl acetate was used as the extractant (1% by molar fraction of 1-ethyl-3-methylimidazolium hexafluorophosphate), and water was used as the washing agent. The flow ratio of extractant, washing agent, and feed solution in the first stage of fractional extraction was 5:5:1, and fractional extraction was carried out at 30°C. The extraction stage consisted of 10 stages, and the washing stage consisted of 6 stages. The extractant entered the fractional extraction system from the first stage of the extraction stage, the feed solution entered from the last stage of the extraction stage, and the washing agent entered from the first stage of the washing stage. The first stage of the washing section produces an extract rich in o-phenylenediamine, while the first stage of the extraction section produces a raffinate rich in m-phenylenediamine and p-phenylenediamine. The extract and raffinate are collected.

[0116] The raffinate from the first stage of fractional extraction serves as the feed for the second stage, entering the fractional extraction system from the last stage of the extraction section. The flow ratio of extractant, washing agent, and feed for the second stage is 10:1:1. Fractional extraction is carried out at 30°C, with 10 stages in the extraction section and 6 stages in the washing section. The remaining operations are the same as the first stage. The extract rich in m-phenylenediamine flows out from the first stage of the washing section, and the raffinate rich in p-phenylenediamine flows out from the first stage of the extraction section. Both the extract and the raffinate are collected.

[0117] The extract and raffinate were concentrated under vacuum, washed with water, and dried to obtain o-phenylenediamine, m-phenylenediamine, and p-phenylenediamine. The purity of o-phenylenediamine was 99.33%, with a yield of 96.34%; the purity of m-phenylenediamine was 99.68%, with a yield of 96.98%; and the purity of p-phenylenediamine was 99.74%, with a yield of 99.01%.

[0118] Example 13

[0119] A mixture of m-phenylenediamine, o-phenylenediamine, and p-phenylenediamine (with m-phenylenediamine comprising 90% by mass, o-phenylenediamine 8% by mass, and p-phenylenediamine 2% by mass) was dissolved in water to prepare a feed solution with a total concentration of 5 g / L. A mixed solvent of 1-ethyl-3-methylimidazolium hexafluorophosphate and ethyl acetate was used as the extractant (1-ethyl-3-methylimidazolium hexafluorophosphate molar fraction 0.1%), and water was used as the washing agent. The flow ratio of extractant, washing agent, and feed solution in the first stage of fractional extraction was 5:5:1, and fractional extraction was carried out at 30°C. The extraction stage consisted of 10 stages, and the washing stage consisted of 6 stages. The extractant entered the fractional extraction system from the first stage of the extraction stage, the feed solution entered from the last stage of the extraction stage, and the washing agent entered from the first stage of the washing stage. The first stage of the washing section produces an extract rich in o-phenylenediamine, while the first stage of the extraction section produces a raffinate rich in m-phenylenediamine and p-phenylenediamine. The extract and raffinate are collected.

[0120] The raffinate from the first stage of fractional extraction serves as the feed for the second stage, entering the fractional extraction system from the last stage of the extraction section. The flow ratio of extractant, washing agent, and feed for the second stage is 10:1:1. Fractional extraction is carried out at 30°C, consisting of 6 stages in the extraction section and 3 stages in the washing section. The remaining operations are the same as the first stage. The extract rich in m-phenylenediamine flows out from the first stage of the washing section, and the raffinate rich in p-phenylenediamine flows out from the first stage of the extraction section. Both the extract and the raffinate are collected.

[0121] The extract and raffinate were concentrated under vacuum, washed with water, and dried to obtain o-phenylenediamine, m-phenylenediamine, and p-phenylenediamine. The purity of o-phenylenediamine was 98.33%, with a yield of 95.34%; the purity of m-phenylenediamine was 97.65%, with a yield of 95.74%; and the purity of p-phenylenediamine was 97.85%, with a yield of 97.26%.

[0122] Example 14

[0123] A mixture of m-phenylenediamine, o-phenylenediamine, and p-phenylenediamine (with m-phenylenediamine comprising 90% by mass, o-phenylenediamine 8% by mass, and p-phenylenediamine 2% by mass) was dissolved in water to prepare a feed solution with a total concentration of 5 g / L. A mixed solvent of 1-ethyl-3-methylimidazolium hexafluorophosphate and ethyl acetate was used as the extractant (1-ethyl-3-methylimidazolium hexafluorophosphate molar fraction 50%), and water was used as the washing agent. The flow ratio of extractant, washing agent, and feed solution in the first stage of fractional extraction was 5:5:1, and fractional extraction was carried out at 30°C. The extraction stage consisted of 10 stages, and the washing stage consisted of 6 stages. The extractant entered the fractional extraction system from the first stage of the extraction stage, the feed solution entered from the last stage of the extraction stage, and the washing agent entered from the first stage of the washing stage. The first stage of the washing section produces an extract rich in o-phenylenediamine, while the first stage of the extraction section produces a raffinate rich in m-phenylenediamine and p-phenylenediamine. The extract and raffinate are collected.

[0124] The raffinate from the first stage of fractional extraction serves as the feed for the second stage, entering the fractional extraction system from the last stage of the extraction section. The flow ratio of extractant, washing agent, and feed for the second stage is 10:1:1. Fractional extraction is carried out at 30°C, consisting of 6 stages in the extraction section and 3 stages in the washing section. The remaining operations are the same as the first stage. The extract rich in m-phenylenediamine flows out from the first stage of the washing section, and the raffinate rich in p-phenylenediamine flows out from the first stage of the extraction section. Both the extract and the raffinate are collected.

[0125] The extract and raffinate were concentrated under vacuum, washed with water, and dried to obtain o-phenylenediamine, m-phenylenediamine, and p-phenylenediamine. The purity of o-phenylenediamine was 99.84%, with a yield of 97.56%; the purity of m-phenylenediamine was 99.75%, with a yield of 97.97%; and the purity of p-phenylenediamine was 99.03%, with a yield of 98.23%.

[0126] Example 15

[0127] A mixture of m-phenylenediamine, o-phenylenediamine, and p-phenylenediamine (with m-phenylenediamine comprising 90% by mass, o-phenylenediamine 8% by mass, and p-phenylenediamine 2% by mass) was dissolved in water to prepare a feed solution with a total concentration of 5 g / L. A mixed solvent of 1-ethyl-3-methylimidazolium hexafluorophosphate and ethyl acetate was used as the extractant (1-ethyl-3-methylimidazolium hexafluorophosphate molar fraction 90%), and water was used as the washing agent. The flow ratio of extractant, washing agent, and feed solution in the first stage of fractional extraction was 5:5:1, and fractional extraction was carried out at 30°C. The extraction stage consisted of 10 stages, and the washing stage consisted of 6 stages. The extractant entered the fractional extraction system from the first stage of the extraction stage, the feed solution entered from the last stage of the extraction stage, and the washing agent entered from the first stage of the washing stage. The first stage of the washing section produces an extract rich in o-phenylenediamine, while the first stage of the extraction section produces a raffinate rich in m-phenylenediamine and p-phenylenediamine. The extract and raffinate are collected.

[0128] The raffinate from the first stage of fractional extraction serves as the feed for the second stage, entering the fractional extraction system from the last stage of the extraction section. The flow ratio of extractant, washing agent, and feed for the second stage is 10:1:1. Fractional extraction is carried out at 30°C, consisting of 6 stages in the extraction section and 3 stages in the washing section. The remaining operations are the same as the first stage. The extract rich in m-phenylenediamine flows out from the first stage of the washing section, and the raffinate rich in p-phenylenediamine flows out from the first stage of the extraction section. Both the extract and the raffinate are collected.

[0129] The extract and raffinate were concentrated under vacuum, washed with water, and dried to obtain o-phenylenediamine, m-phenylenediamine, and p-phenylenediamine. The purity of o-phenylenediamine was 98.89%, with a yield of 97.32%; the purity of m-phenylenediamine was 99.24%, with a yield of 97.61%; and the purity of p-phenylenediamine was 98.51%, with a yield of 97.67%.

[0130] Comparative Example 1

[0131] A mixture of m-phenylenediamine, o-phenylenediamine, and p-phenylenediamine (with m-phenylenediamine comprising 90% by mass, o-phenylenediamine 8% by mass, and p-phenylenediamine 2% by mass) was dissolved in water to prepare a feed solution with a total concentration of 5 g / L. Butyl acetate was used as the extractant and water as the washing agent. The flow ratio of extractant, washing agent, and feed solution in the first stage of fractional extraction was 5:5:1, and fractional extraction was carried out at 30°C. The extraction stage consisted of 10 stages, and the washing stage consisted of 6 stages. The extractant entered the fractional extraction system from the first stage of the extraction stage, the feed solution entered from the last stage of the extraction stage, and the washing agent entered from the first stage of the washing stage. An extract rich in o-phenylenediamine flowed out from the first stage of the washing stage, and a raffinate rich in m-phenylenediamine and p-phenylenediamine flowed out from the first stage of the extraction stage. Both the extract and the raffinate were collected.

[0132] The raffinate from the first stage of fractional extraction serves as the feed for the second stage, entering the fractional extraction system from the last stage of the extraction section. The flow ratio of extractant, washing agent, and feed for the second stage is 10:1:1. Fractional extraction is carried out at 30°C, consisting of 6 stages in the extraction section and 3 stages in the washing section. The remaining operations are the same as the first stage. The extract rich in m-phenylenediamine flows out from the first stage of the washing section, and the raffinate rich in p-phenylenediamine flows out from the first stage of the extraction section. Both the extract and the raffinate are collected.

[0133] The extract and raffinate were concentrated under vacuum, washed with water, and dried to obtain o-phenylenediamine, m-phenylenediamine, and p-phenylenediamine. The purity of o-phenylenediamine was 84.28%, with a yield of 85.36%; the purity of m-phenylenediamine was 89.64%, with a yield of 82.97%; and the purity of p-phenylenediamine was 80.34%, with a yield of 80.25%.

[0134] Comparative Example 2

[0135] A mixture of m-phenylenediamine, o-phenylenediamine, and p-phenylenediamine (with m-phenylenediamine comprising 90% by mass, o-phenylenediamine 8% by mass, and p-phenylenediamine 2% by mass) was dissolved in water to prepare a feed solution with a total concentration of 5 g / L. Hexanol was used as the extractant and water as the washing agent. The flow ratio of extractant, washing agent, and feed solution in the first stage of fractional extraction was 5:5:1, and fractional extraction was carried out at 30°C. The extraction stage consisted of 10 stages, and the washing stage consisted of 6 stages. The extractant entered the fractional extraction system from the first stage of the extraction stage, the feed solution entered from the last stage of the extraction stage, and the washing agent entered from the first stage of the washing stage. An extract rich in o-phenylenediamine flowed out from the first stage of the washing stage, and a raffinate rich in m-phenylenediamine and p-phenylenediamine flowed out from the first stage of the extraction stage. Both the extract and the raffinate were collected.

[0136] The raffinate from the first stage of fractional extraction serves as the feed for the second stage, entering the fractional extraction system from the last stage of the extraction section. The flow ratio of extractant, washing agent, and feed for the second stage is 10:1:1. Fractional extraction is carried out at 30°C, consisting of 6 stages in the extraction section and 3 stages in the washing section. The remaining operations are the same as the first stage. The extract rich in m-phenylenediamine flows out from the first stage of the washing section, and the raffinate rich in p-phenylenediamine flows out from the first stage of the extraction section. Both the extract and the raffinate are collected.

[0137] The extract and raffinate were concentrated under vacuum, washed with water, and dried to obtain o-phenylenediamine, m-phenylenediamine, and p-phenylenediamine. The purity of o-phenylenediamine was 90.44%, with a yield of 90.13%; the purity of m-phenylenediamine was 82.67%, with a yield of 89.79%; and the purity of p-phenylenediamine was 87.52%, with a yield of 80.17%.

[0138] Comparative Example 3

[0139] A mixture of m-phenylenediamine, o-phenylenediamine, and p-phenylenediamine (with m-phenylenediamine comprising 90% by mass, o-phenylenediamine 8% by mass, and p-phenylenediamine 2% by mass) was dissolved in water to prepare a feed solution with a total concentration of 5 g / L. 3-Pentanone was used as the extractant and water as the washing agent. The flow ratio of extractant, washing agent, and feed solution in the first stage of fractional extraction was 5:5:1, and fractional extraction was carried out at 30°C. The extraction stage consisted of 10 stages, and the washing stage consisted of 6 stages. The extractant entered the fractional extraction system from the first stage of the extraction stage, the feed solution entered from the last stage of the extraction stage, and the washing agent entered from the first stage of the washing stage. An extract rich in o-phenylenediamine flowed out from the first stage of the washing stage, and a raffinate rich in m-phenylenediamine and p-phenylenediamine flowed out from the first stage of the extraction stage. Both the extract and the raffinate were collected.

[0140] The raffinate from the first stage of fractional extraction serves as the feed for the second stage, entering the fractional extraction system from the last stage of the extraction section. The flow ratio of extractant, washing agent, and feed for the second stage is 10:1:1. Fractional extraction is carried out at 30°C, consisting of 6 stages in the extraction section and 3 stages in the washing section. The remaining operations are the same as the first stage. The extract rich in m-phenylenediamine flows out from the first stage of the washing section, and the raffinate rich in p-phenylenediamine flows out from the first stage of the extraction section. Both the extract and the raffinate are collected.

[0141] The extract and raffinate were concentrated under vacuum, washed with water, and dried to obtain o-phenylenediamine, m-phenylenediamine, and p-phenylenediamine. The purity of o-phenylenediamine was 93.20%, with a yield of 92.57%; the purity of m-phenylenediamine was 94.46%, with a yield of 92.14%; and the purity of p-phenylenediamine was 91.80%, with a yield of 90.75%.

[0142] Comparative Example 4

[0143] A mixture of m-phenylenediamine, o-phenylenediamine, and p-phenylenediamine (with m-phenylenediamine comprising 90% by mass, o-phenylenediamine 8% by mass, and p-phenylenediamine 2% by mass) was dissolved in water to prepare a feed solution with a total concentration of 5 g / L. Tributyl phosphate was used as the extractant and water as the washing agent. The flow ratio of extractant, washing agent, and feed solution in the first stage of fractional extraction was 5:5:1, and fractional extraction was carried out at 30°C. The extraction stage consisted of 10 stages, and the washing stage consisted of 6 stages. The extractant entered the fractional extraction system from the first stage of the extraction stage, the feed solution entered from the last stage of the extraction stage, and the washing agent entered from the first stage of the washing stage. An extract rich in o-phenylenediamine flowed out from the first stage of the washing stage, and a raffinate rich in m-phenylenediamine and p-phenylenediamine flowed out from the first stage of the extraction stage. Both the extract and the raffinate were collected.

[0144] The raffinate from the first stage of fractional extraction serves as the feed for the second stage, entering the fractional extraction system from the last stage of the extraction section. The flow ratio of extractant, washing agent, and feed for the second stage is 10:1:1. Fractional extraction is carried out at 30°C, consisting of 6 stages in the extraction section and 3 stages in the washing section. The remaining operations are the same as the first stage. The extract rich in m-phenylenediamine flows out from the first stage of the washing section, and the raffinate rich in p-phenylenediamine flows out from the first stage of the extraction section. Both the extract and the raffinate are collected.

[0145] The extract and raffinate were concentrated under vacuum, washed with water, and dried to obtain o-phenylenediamine, m-phenylenediamine, and p-phenylenediamine. The purity of o-phenylenediamine was 96.43%, with a yield of 95.89%; the purity of m-phenylenediamine was 97.21%, with a yield of 92.45%; and the purity of p-phenylenediamine was 93.16%, with a yield of 90.47%.

[0146] The above embodiments are merely examples of several implementation methods of the present invention and are not intended to limit it. Any technical modifications made according to the technical solutions of the present invention shall fall within the protection scope of the present invention.

Claims

1. A method for separating phenylenediamine isomers, comprising fractionating and extracting a feed liquid containing phenylenediamine isomers using an extractant containing an ionic liquid.

2. The method according to claim 1, characterized in that, The cation of the ionic liquid is selected from one or more of the following: imidazole cation, quinoline cation, choline cation, pyridine cation, quaternary ammonium cation, quaternary phosphorus cation, pyrrolidine cation, guanidine cation, amino acid cation, quinine ring cation, benzimidazole cation, benzothiophene cation, and benzofuran cation; and / or, The anion of the ionic liquid is selected from one or more of the following: chloride ion, bromide ion, iodide ion, sulfate ion, sulfite ion, sulfonate ion, thiocyanate ion, dicyandiamide ion, tetrafluoroborate ion, tricyanomethane ion, trifluoromethanesulfonate ion, tetracyanoborate ion, hexafluorophosphate ion, nitrate ion, acetate ion, lactate ion, acetylsulimide anion, bis((trifluoromethyl)sulfonyl)imide anion, or amino acid anion. Optionally, the cation is substituted by one or more substituents selected from alkyl, alkenyl, aryl, cyano, thiocyano, sulfonyl, carbonyl, and cyanoalkyl; preferably, the alkyl is a C1-C8 straight-chain or branched alkyl, more preferably a C1-C4 straight-chain alkyl, the alkenyl is a C2-C8 alkenyl, more preferably a C2-C4 straight-chain alkenyl, the aryl is a C6-C15 aryl, more preferably a phenyl, and the cyanoalkyl is a cyano-substituted C1-C8 straight-chain or branched alkyl, more preferably a cyano-substituted C1-C4 straight-chain alkyl.

3. The method according to claim 1 or 2, characterized in that, The ionic liquid comprises one or more of the following: 1-ethyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-methylimidazolium hexafluorophosphate, 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium iodide, 1-(butonitrile-3-methylimidazolium)bis((trifluoromethyl)sulfonyl)imide, choline chloride, tributylammonium chloride, 1-hexyl-3-methylimidazolium trifluoromethanesulfonate, 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, and 1-ethyl-3-methylimidazolium dicyandiamide; Preferably, the ionic liquid comprises one or more of 1-ethyl-3-methylimidazolium hexafluorophosphate, 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium iodide, and 1-(butyronitrile-3-methylimidazolium)bis((trifluoromethyl)sulfonyl)imide.

4. The method according to any one of claims 1 to 3, characterized in that, Based on the total molar amount of the extractant, the molar percentage of the ionic liquid is 0.01% to 100%, preferably 0.05% to 90%, more preferably 0.1% to 10%, and even more preferably 0.5% to 5%.

5. The method according to any one of claims 1 to 4, characterized in that, The extractant is selected from at least one of ionic liquids, combinations of ionic liquids and water, and combinations of ionic liquids and organic solvents; wherein the organic solvent includes one or more of oxygen-containing organic solvents, phosphorus-containing organic solvents, nitrogen-containing organic solvents, and sulfur-containing organic solvents. Preferably, the oxygen-containing organic solvent includes one or more of esters, alcohols, ketones, and ethers; more preferably, it includes one or more of C2-C10 esters, C4-C10 alcohols, C4-C10 ketones, and C2-C10 ethers; even more preferably, it includes one or more of methyl acetate, ethyl acetate, propyl acetate, butyl acetate, n-butanol, isobutanol, n-pentanol, isopentanol, n-hexanol, 2-hexanol, n-heptanol, isooctanol, 2-pentanone, 3-pentanone, cyclohexanone, acetylacetone, methyl isobutyl ketone, diethyl ether, methyl tert-butyl ether, petroleum ether, and 1,4-dioxane. Preferably, the phosphorus-containing organic solvent includes phosphonates and / or alkylphosphine oxides; more preferably, it includes one or more of tributyl phosphate, trioctylphosphine oxide, and 2,4,6-trimethylbenzoyl-diphenylphosphine oxide. Preferably, the nitrogen-containing organic solvent includes one or more of amides, tertiary amines, and quaternary ammonium salts; more preferably, it includes one or more of N,N-dimethylheptylacetamide, trioctylamine, trioctyldecyl tertiary amine, and trialkylmethylamine chloride. Preferably, the sulfur-containing organic solvent includes sulfonic acid organic solvents, more preferably dodecylbenzenesulfonic acid and / or dinonylnaphthalenesulfonic acid; Preferably, the extractant comprises an ionic liquid and a combination thereof selected from one or more of the following: water, methyl acetate, ethyl acetate, butyl acetate, n-butanol, isobutanol, n-hexanol, n-octanol, methyl tert-butyl ether, 2-pentanone, 3-pentanone, cyclohexanone, acetylacetone, and 1,4-dioxane. Preferably, the extractant is selected from at least one of ionic liquids, combinations of ionic liquids and water, combinations of ionic liquids and n-butanol, and combinations of ionic liquids and ethyl acetate; Preferably, the extractant is selected from at least one of the following: a combination of 1-ethyl-3-methylimidazolium hexafluorophosphate and ethyl acetate; a combination of 1-ethyl-3-methylimidazolium hexafluorophosphate and n-butanol; 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide; 1-ethyl-3-methylimidazolium tetrafluoroborate; a combination of 1-ethyl-3-methylimidazolium iodide and water; and a combination of 1-(butyronitrile-3-methylimidazolium)bis((trifluoromethyl)sulfonyl)imide and ethyl acetate.

6. The method according to any one of claims 1 to 5, characterized in that, The phenylenediamine isomers include any two or three of o-phenylenediamine, m-phenylenediamine, and p-phenylenediamine; Preferably, the mass ratio of o-phenylenediamine to p-phenylenediamine in the raw material solution is (1-10):1; and / or, the mass ratio of m-phenylenediamine to p-phenylenediamine in the raw material solution is (10-50):1; and / or, the mass ratio of o-phenylenediamine to m-phenylenediamine in the raw material solution is (0.02-1):

1.

7. The method according to any one of claims 1 to 6, characterized in that, The feed liquid also includes a feed solvent, which is the same as or different from, preferably the same as, the detergent used in the fractionation extraction, and is independently selected from water, C2-C10 ester solvents, C2-C10 alcohol solvents, or C2-C10 ketone solvents, preferably selected from at least one of water, methyl acetate, ethyl acetate, butyl acetate, n-butanol, isobutanol, n-pentanol, isopentanol, n-hexanol, 2-hexanol, n-heptanol, isooctanol, hexanone, and cyclohexanone; more preferably selected from water or ethyl acetate; and / or, In the fractional extraction, the flow ratio of the extractant to the feed liquid is (1-15):1, preferably (5-10):1; and / or, In the fractional extraction, the flow ratio of the detergent to the feed liquid is (0.1-10):1, preferably (1-5):

1.

8. The method according to any one of claims 1 to 7, characterized in that, The total concentration of phenylenediamine isomers in the feed solution is 0.1 g / L to 200.0 g / L, preferably 0.1 g / L to 100.0 g / L, more preferably 1 g / L to 20.0 g / L; and / or, The fractionation extraction temperature is 20℃~70℃; and / or, The fractionation extraction time is 5 min to 200 min.

9. The method according to any one of claims 1 to 8, characterized in that, The method includes the following steps: The phenylenediamine isomer is mixed with the raw material solvent to obtain a raw material solution; The feed liquid is subjected to a first fractional extraction using the ionic liquid-containing extractant to obtain a first extract and a first raffinate. Preferably, the method further includes the steps of concentrating, washing and drying the first extract.

10. The method according to claim 9, characterized in that, The method further includes the steps of concentrating, washing, and drying the first raffinate; or... The first raffinate is subjected to a second fractional extraction using the ionic liquid-containing extractant to obtain a second extract and a second raffinate. Preferably, the method further includes the steps of concentrating, washing and drying the second extract and / or the second raffinate.

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