High-efficiency and low-energy-consumption treatment method for 1, 2, 4-1H triazole crystallization mother liquor

Abstract

The invention discloses a high-efficiency and low-energy-consumption treatment method of 1, 2, 4-1H triazole crystallization mother liquor, which comprises the following steps: S1, carrying out primary treatment on the 1, 2, 4-1H triazole crystallization mother liquor by adopting rough filtration-nanofiltration-reverse osmosis; s2, carrying out catalytic oxidation treatment by adopting sodium persulfate and an MOF derived Co (at) C nanocage catalyst; s3, carrying out deep purification by adopting an ion exchange mixed bed system; and S4, solvent recovery and reuse. Compared with the prior art, the method not only solves the problem of treatment of the 1, 2, 4-1H triazole crystallization mother liquor, but also realizes cyclic utilization of resources, and accords with the development concepts of green chemical industry and circular economy.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical synthesis, and particularly relates to a method for treating the crystallization mother liquor of 1,2,4-1H-triazole with high efficiency and low energy consumption. Background Art

[0002] 1,2,4-1H-triazole is an important nitrogen-containing heterocyclic compound, which is widely used in the fields of medicine, pesticides, explosives, dyes, and materials. As a key chemical intermediate, its purity and quality directly affect the performance and safety of downstream products. The traditional production process of 1,2,4-1H-triazole mainly uses methods such as formylhydrazine oxidation cyclization reaction or condensation reaction of formamide and hydrazine, and the final product is obtained through crystallization and purification. However, the crystallization mother liquor usually contains unreacted raw materials, intermediates, isomers, and by-products, and the mother liquor has a high viscosity and complex composition. Directly applying it to the next batch of production will cause the accumulation of impurities step by step, seriously reducing the product purity.

[0003] At present, the existing treatment technologies for 1,2,4-1H-triazole mother liquor in the industry mainly include: multiple recrystallizations, distillation and concentration, extraction and separation, and direct waste treatment; among them, although multiple recrystallizations can improve the purity, the solvent consumption is large, the energy consumption is high, and the yield is low; the distillation and concentration method recovers the solvent and enriches triazole through vacuum distillation, but the energy consumption is high, and it is easy to cause the decomposition of heat-sensitive impurities and generate more complex by-products; the extraction and separation method uses organic solvents to extract and recover triazole, but there is a risk of solvent residue, and the separation efficiency is greatly affected by various factors; direct waste treatment not only wastes raw materials but also increases the environmental protection treatment cost. The above treatment methods all have different degrees of defects, such as complex processes, high energy consumption, low treatment efficiency, serious equipment corrosion, and high risk of secondary pollution. Especially when dealing with a complex mother liquor system containing multiple impurities, it is difficult for traditional methods to achieve the efficient recovery of 1,2,4-1H-triazole and the effective separation of impurities.

[0004] Therefore, developing a method for treating the crystallization mother liquor of 1,2,4-1H-triazole with high efficiency, low energy consumption, and environmental protection, and realizing the recycling of valuable components in the mother liquor and the effective separation of impurities, is of great significance for improving the product quality of 1,2,4-1H-triazole, reducing production costs, and reducing environmental pollution. Summary of the Invention

[0005] Based on the problems existing in the background art, the present invention provides a method for treating the crystallization mother liquor of 1,2,4-1H-triazole with high efficiency and low energy consumption. Compared with the prior art, the present invention not only solves the problem of treating the crystallization mother liquor of 1,2,4-1H-triazole, but also realizes the recycling of resources, which is in line with the development concept of green chemistry and circular economy.

[0006] The present invention is implemented through the following technical solutions:

[0007] An efficient and low - energy consumption method for treating the crystallization mother liquor of 1,2,4 - 1H - triazole, comprising the following steps:

[0008] S1. Conduct preliminary treatment on the crystallization mother liquor of 1,2,4 - 1H - triazole by using coarse filtration - nanofiltration - reverse osmosis to obtain a pretreated mother liquor;

[0009] S2. Add sodium persulfate and MOF - derived Co@C nanocage catalyst to the pretreated mother liquor, adjust the pH to 3 - 5, stir and react at room temperature for 1 - 3 h, and after the reaction is completed, remove the catalyst by filtration to obtain a treated mother liquor;

[0010] S3. Pass the treated mother liquor through an ion - exchange mixed - bed system, collect the effluent to obtain a purified mother liquor;

[0011] S4. Transport the purified mother liquor to a multi - stage molecular distillation device, carry out vacuum distillation, separate and recover the solvent, conduct purity detection on the recovered solvent, and after the recovered solvent meets the process requirements, return it to the front - end synthesis process of 1,2,4 - 1H - triazole; return the distillation residue to the front - end crystallization process of 1,2,4 - 1H - triazole.

[0012] Further, in step S1, the coarse filtration uses a stainless - steel sintered filter element with a pore size of 10 μm, an operating pressure of 0.2 - 0.4 MPa, and a flux of 500 - 800 L / (m 2 ·h).

[0013] Further, the nanofiltration uses a polyamide composite membrane with a molecular weight cut - off of 200 - 400 Da, an operating pressure of 1.5 - 1.8 MPa, and a flux of 30 - 50 L / (m 2 ·h).

[0014] Further, the reverse osmosis uses a polyamide membrane with a molecular weight cut - off of 60 - 150 Da, an operating pressure of 2.5 - 3.0 MPa, and a flux of 20 - 30 L / (m 2 ·h);

[0015] The concentration of the crystallization mother liquor after reverse osmosis treatment is 5 - 6 times that of the initial crystallization mother liquor.

[0016] Further, in step S2, the specific preparation steps of the MOF - derived Co@C nanocage catalyst are as follows:

[0017] S21. Dissolve cobalt(II) nitrate hexahydrate in methanol, mark it as solvent A; dissolve 2 - methylimidazole in methanol, mark it as solvent B; quickly introduce solvent B into solvent A, vigorously stir at room temperature for 30 - 60 min, let the reaction mixture stand, obtain a purple precipitate, centrifuge to collect the precipitate, wash it with methanol, and dry it in vacuum at 60 °C for 12 hours to obtain ZIF - 67 crystals;

[0018] S22. Place the ZIF-67 crystals in a tubular furnace, and introduce N 2 to remove air, and heat it up to 350 °C at a rate of 2 °C / min in N 2 atmosphere, hold for 1 - 2 h, and continue to heat it up to 800 °C at a rate of 5 °C / min in N 2 atmosphere, hold for 2 - 3 h, and cool it to room temperature to obtain black powder;

[0019] S23. Place the black powder in a muffle furnace, oxidize it in air atmosphere at 200 °C for 2 hours, and cool it to room temperature to obtain the MOF-derived Co@C nanocage catalyst.

[0020] Furthermore, in step S2, the dosage of sodium persulfate is 0.5 - 0.8 g / L; the dosage of the MOF-derived Co@C nanocage catalyst is 0.3 - 0.6 g / L.

[0021] Furthermore, in step S2, removing the catalyst by filtration specifically means fine filtration through a 0.45 μm membrane; the filtered catalyst is recycled after pickling.

[0022] The hollow carbon cage structure of the MOF-derived Co@C nanocage catalyst provides a stable nano-reaction space, and the carbon cage protective layer prevents the aggregation of Co nanoparticles. The mesoporous carbon shell of the Co@C nanocage adsorbs small molecule polar impurities (such as semicarbazide, 1,3,4-triazole) through pore size sieving and surface functional groups (-C=O, -OH), and the adsorption capacity reaches 150 mg / g; the carbon cage preferentially adsorbs impurity molecules, while 1,2,4-1H-triazole is blocked in the outer pore channels due to its slightly larger molecular size, avoiding the loss of the main product. The Co nanoparticles encapsulated inside the carbon cage activate persulfate (PMS) to generate SO 4 - · radicals, which directly degrade impurities near the adsorption sites to achieve in-situ adsorption-catalysis synergy.

[0023] Furthermore, in step S3, the volume ratio of cation resin to anion resin in the ion exchange mixed bed system is 1:1; the flow rate is 2 - 4 BV / h.

[0024] Furthermore, the cation resin is a strongly acidic styrene-based resin; the anion resin is a strongly basic styrene-based resin.

[0025] Furthermore, in step S4, the conditions for vacuum distillation are 55 - 65 °C, 50 - 100 MPa.

[0026] Advantages of the present invention:

[0027] 1. High processing efficiency: Through the multi-stage membrane separation technology of coarse filtration - nanofiltration - reverse osmosis, combined with catalytic oxidation, ion exchange, and molecular distillation processes, it can efficiently remove impurities in the mother liquor and achieve high-purity recovery of the solvent.

[0028] 2. Low energy consumption: Adopting the processes of room-temperature catalytic oxidation and low-temperature molecular distillation significantly reduces energy consumption; the catalyst can be recycled, reducing material consumption.

[0029] 3. Good environmental protection: Achieves closed-loop treatment of the mother liquor, and the recycled solvent returns to the production process, reducing waste liquid discharge and raw material consumption.

[0030] 4. High product quality: Through multi-stage fine treatment, the recycled solvent has high purity and meets the requirements of the production process.

[0031] 5. Significant economic benefits: Recycling and reusing the solvent reduces production costs, the recycling of the catalyst improves economic efficiency, and the treated mother liquor returning to the production process realizes the maximization of resource utilization. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The drawings are used to provide further explanation of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation to the present invention. In the drawings:

[0033] Figure 1 is a flowchart of the method for treating the crystallization mother liquor of 1,2,4 - 1H triazole of the present invention;

[0034] Figure 2 is the liquid chromatogram of the mother liquor after treatment in Example 1 of the present invention;

[0035] Figure 3 is the liquid chromatogram of the mother liquor after treatment in Example 2 of the present invention;

[0036] Figure 4 is the liquid chromatogram of the mother liquor after treatment in Example 3 of the present invention;

[0037] Figure 5 is the liquid chromatogram of the mother liquor after treatment in Comparative Example 1 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0038] The following further details the technical solutions of the present invention with specific embodiments, but the protection scope of the present invention is not limited to the following embodiments only.

[0039] Example 1

[0040] A method for treating the crystallization mother liquor of 1,2,4 - 1H triazole with high efficiency and low energy consumption, comprising the following steps:

[0041] S1. Preliminary treatment of the 1,2,4-1H-triazole crystallization mother liquor is carried out by coarse filtration - nanofiltration - reverse osmosis.

[0042] Coarse filtration: Use a stainless steel sintered filter element with a pore size of 10 μm, an operating pressure of 0.3 MPa, and a flux of 650 L / (m 2 ·h) to remove large particle impurities in the mother liquor;

[0043] Nanofiltration: Use a polyamide composite membrane with a molecular weight cut-off of 300 Da, an operating pressure of 1.6 MPa, and a flux of 40 L / (m 2 ·h) to remove macromolecular organic substances in the mother liquor;

[0044] Reverse osmosis: Use a polyamide membrane with a molecular weight cut-off of 100 Da, an operating pressure of 2.8 MPa, and a flux of 25 L / (m 2 ·h) to concentrate the mother liquor to 5.5 times the initial concentration to obtain a pretreated mother liquor.

[0045] S2. Add 0.6 g / L of sodium persulfate and 0.4 g / L of MOF-derived Co@C nanocage catalyst to the pretreated mother liquor, adjust the pH to 4 with sulfuric acid, stir and react at room temperature for 2 h. After the reaction is completed, finely filter through a 0.45 μm membrane to remove the catalyst. The catalyst is recycled after pickling to obtain a treated mother liquor.

[0046] Among them, the preparation of the MOF-derived Co@C nanocage catalyst:

[0047] Dissolve 2.91 parts of cobalt(II) nitrate hexahydrate in 100 parts of methanol by weight, marked as solvent A;

[0048] Dissolve 3.28 parts of 2-methylimidazole in 100 parts of methanol by weight, marked as solvent B;

[0049] Quickly pour solvent B into solvent A, stir vigorously at room temperature for 45 min, let the reaction mixture stand, collect the purple precipitate, wash it with methanol, and dry it in vacuum at 60 °C for 12 h to obtain ZIF-67 crystals;

[0050] Place the ZIF-67 crystals in a tubular furnace, introduce N 2 to remove air, heat up to 350 °C at a rate of 2 °C / min in N 2 atmosphere, hold for 1.5 h, then continue to heat up to 800 °C at a rate of 5 °C / min in N 2 atmosphere, hold for 2.5 h, and cool to room temperature to obtain a black powder;

[0051] Place the black powder in a muffle furnace, oxidize it in air at 200 °C for 2 h, and cool to room temperature to obtain the MOF-derived Co@C nanocage catalyst.

[0052] S3. Pass the treated mother liquor through an ion exchange mixed bed system, collect the effluent, and obtain the purified mother liquor. In the ion exchange mixed bed system, a strongly acidic styrene-based cation resin and a strongly basic styrene-based anion resin are used, with a volume ratio of 1:1 and a flow rate of 3 BV / h.

[0053] Step S4: Transport the purified mother liquor to a multi-stage molecular distillation device, perform vacuum distillation at 60 °C and 75 MPa, separate and recover the solvent, conduct gas chromatography purity detection on the recovered solvent, and when the purity of the recovered solvent reaches over 99.5%, return the recovered solvent to the front-end synthesis process of 1,2,4-1H-triazole; return the distillation residue to the front-end crystallization process of 1,2,4-1H-triazole.

[0054] Through the above treatment method, the recovery rate of the solvent in the 1,2,4-1H-triazole crystallization mother liquor reaches 95%, the purity of the recovered solvent is 99.5%, meeting the production process requirements; the purity of triazole in the treated mother liquor is 99.8%, Co 2+ residual is less than 0.005 ppm, and the recovery rate of triazole is 96.4%; the energy consumption of the entire treatment process is 40% lower than that of the traditional distillation method, achieving efficient and low-energy consumption treatment.

[0055] Example 2

[0056] The treatment method is basically the same as that of Example 1, except that:

[0057] In step S1: The operation pressure of the coarse filtration is 0.2 MPa, and the flux is 500 L / (m 2 ·h); the molecular weight cut-off of the nanofiltration is 200 Da, the operation pressure is 1.5 MPa, and the flux is 30 L / (m 2 ·h); the molecular weight cut-off of the reverse osmosis is 60 Da, the operation pressure is 2.5 MPa, and the flux is 20 L / (m 2 ·h).

[0058] In step S2: The dosage of sodium persulfate is 0.5 g / L; the dosage of the MOF-derived Co@C nanocage catalyst is 0.3 g / L; the pH is adjusted to 3; and the stirring reaction is carried out for 1 h.

[0059] In step S3: The flow rate is 2 BV / h.

[0060] In step S4: The conditions for vacuum distillation are 55 °C and 50 MPa.

[0061] Through the above treatment method, the recovery rate of the solvent in the 1,2,4-1H-triazole crystallization mother liquor reaches over 93%, the purity of the recovered solvent is 99.6%, meeting the production process requirements; the purity of triazole in the treated mother liquor is 99.7%, Co 2+The residue is less than 0.005 ppm, and the recovery rate of triazole is 95.6%; the energy consumption of the whole treatment process is 35% lower than that of the traditional distillation method.

[0062] Example 3

[0063] The treatment method is basically the same as that of Example 1, except that:

[0064] In step S1: the rough filtration operating pressure is 0.4 MPa, and the flux is 800 L / (m 2 ·h); the molecular weight cut-off of nanofiltration is 400 Da, the operating pressure is 1.8 MPa, and the flux is 50 L / (m 2 ·h); the molecular weight cut-off of reverse osmosis is 150 Da, the operating pressure is 3.0 MPa, and the flux is 30 L / (m 2 ·h).

[0065] In step S2: the dosage of sodium persulfate is 0.8 g / L; the dosage of MOF-derived Co@C nanocage catalyst is 0.6 g / L; the pH is adjusted to 5; and the stirring reaction is carried out for 3 h.

[0066] In step S3: the flow rate is 4 BV / h.

[0067] In step S4: the conditions for vacuum distillation are 65 °C and 100 MPa.

[0068] Through the above treatment method, the recovery rate of the solvent in the 1,2,4-1H triazole crystallization mother liquor reaches 96%, the purity of the recovered solvent is 99.8%, meeting the requirements of the production process; the purity of triazole in the treated mother liquor is 99.7%, and the Co 2+ residue is less than 0.005 ppm, and the recovery rate of triazole is 96.1%; the energy consumption of the whole treatment process is 45% lower than that of the traditional distillation method.

[0069] Comparative Example 1

[0070] The difference between this comparative example and Example 1 is that a common cobalt-based catalyst is used. The preparation method of the common cobalt-based catalyst is as follows: γ-Al 2 O 3 (particle size 3-5 mm, specific surface area 200 m 2 / g) is used as the carrier, and γ-Al 2 O 3 is immersed in cobalt nitrate solution for 12 hours, dried at 120 °C, and calcined in air at 500 °C for 3 h to obtain a common cobalt-based catalyst.

[0071] Except for the catalyst replacement, the remaining treatment steps are the same as those in Example 1.

[0072] Through the above treatment method, the purity of triazole in the treated mother liquor is 98.1%, and Co 2+The residue is 0.5 ppm, and the recovery rate of triazole is 92.6%.

[0073] In this comparative example, the common cobalt-based catalyst has a low specific surface area and poor dispersion of active sites, and the free radical yield is only 40% of that of the MOF-derived Co@C nanocage catalyst; in addition, the common cobalt-based catalyst lacks confinement protection, and SO 4 - · Free radicals attack the triazole ring indiscriminately and also oxidize the N-H bond of triazole to generate oxygen-containing by-products, which become new impurities and lead to a decrease in the yield of the main product.

[0074] Finally, it should be noted that the above embodiments only represent several implementation manners of the present invention and are not intended to limit the present invention. For those of ordinary skill in the art, any modifications, equivalent replacements, improvements, etc. made without departing from the concept of the present invention should be included within the protection scope of the present invention. Therefore, the protection scope of this invention patent shall be subject to the appended claims.

Claims

1. A high-efficiency, low-energy method for treating 1,2,4-1H triazole crystallization mother liquor, characterized in that: The following steps are involved: S1. Preliminary treatment of the 1,2,4-1H triazole crystallization mother liquor by coarse filtration-nanofiltration-reverse osmosis to obtain a pretreated mother liquor; S2. Add sodium persulfate and MOF-derived Co@C nanocage catalyst to the pretreated mother liquor, adjust the pH to 3-5, stir and react at room temperature for 1-3 hours, and remove the catalyst through a membrane after the reaction is completed to obtain a treated mother liquor; S3. The treated mother liquor is passed through an ion exchange mixed bed system, and the effluent is collected to obtain a purified mother liquor; S4. The purified mother liquor is transported to a multi-stage molecular distillation device for vacuum distillation to separate and recover the solvent, and the recovered solvent is tested for purity. After the recovered solvent meets the process requirements, it is returned to the 1,2,4-1H triazole front-end synthesis process; the distillation residue is returned to the 1,2,4-1H triazole front-end crystallization process.

2. The method for treating the 1,2,4-1H triazole crystallization mother liquor with high efficiency and low energy consumption according to claim 1, characterized in that: In step S1, the coarse filtration uses a stainless steel sintered filter element with a pore size of 10 μm, an operating pressure of 0.2-0.4 MPa, and a flux of 500-800 L / (m 2 h).

3. The method for treating the 1,2,4-1H triazole crystallization mother liquor with high efficiency and low energy consumption according to claim 1, characterized in that: Nanofiltration uses polyamide composite membrane with a molecular weight cutoff of 200-400Da, an operating pressure of 1.5-1.8MPa, and a flux of 30-50L / (m 2 h).

4. The method for treating the 1,2,4-1H triazole crystal mother liquor with high efficiency and low energy consumption according to claim 1, characterized in that: Reverse osmosis uses polyamide mold, with a molecular weight cutoff of 60-150Da, an operating pressure of 2.5-3.0MPa, and a flux of 20-30L / (m 2 h); The concentration of the crystallization mother liquor after reverse osmosis treatment is 5-6 times the concentration of the initial crystallization mother liquor.

5. The method for treating the 1,2,4-1H triazole crystallization mother liquor with high efficiency and low energy consumption according to claim 1, characterized in that: In step S2, the specific preparation steps of the MOF-derived Co@C nanocage catalyst are: S21. Dissolve cobalt nitrate hexahydrate in methanol, labeled as solvent A; dissolve 2-methylimidazole in methanol, labeled as solvent B; quickly introduce solvent B into solvent A, vigorously stir at room temperature for 30-60 minutes, let the reaction mixture stand to obtain a purple precipitate, collect the precipitate by centrifugation, wash with methanol, and vacuum dry at 60°C for 12 hours to obtain ZIF-67 crystals; S22. The ZIF-67 crystal was placed in a tube furnace, N2 was introduced to exclude air, the temperature was raised to 350°C at 2°C / min in N2 atmosphere, maintained for 1-2h, and then the temperature was raised to 800°C at 5°C / min in N2 atmosphere, maintained for 2-3h, and cooled to room temperature to obtain a black powder; S23. The black powder was placed in a muffle furnace, oxidized at 200°C in an air atmosphere for 2 hours, and cooled to room temperature to obtain a MOF-derived Co@C nanocage catalyst.

6. The method for treating the 1,2,4-1H triazole crystallization mother liquor with high efficiency and low energy consumption according to claim 1, characterized in that: In step S2, the dosage of sodium persulfate is 0.5-0.8 g / L; the dosage of MOF-derived Co@C nanocage catalyst is 0.3-0.6 g / L.

7. The method for treating the 1,2,4-1H triazole crystallization mother liquor with high efficiency and low energy consumption according to claim 1, characterized in that: In step S2, the catalyst is removed through a membrane by fine filtration through a 0.45 μm membrane; the filtered catalyst is acid-washed and then recycled.

8. The method for treating the 1,2,4-1H triazole crystal mother liquor with high efficiency and low energy consumption according to claim 1, characterized in that: In step S3, the volume ratio of the cation resin to the anion resin in the ion exchange mixed bed system is 1:1; and the flow rate is 2-4 BV / h.

9. The method for treating the 1,2,4-1H triazole crystallization mother liquor with high efficiency and low energy consumption according to claim 8, characterized in that: Cationic resin is a strongly acidic styrene resin; anionic resin is a strongly basic styrene resin.

10. The method for treating the 1,2,4-1H triazole crystallization mother liquor with high efficiency and low energy consumption according to claim 1, characterized in that: In step S4, the conditions for reduced pressure distillation are 55-65° C. and 50-100 MPa.

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