Coupling purification method of electronic-grade N-methyl pyrrolidone

Abstract

The invention belongs to the technical field of purification of electronic chemicals, and particularly relates to a method for coupling and purifying electronic-grade N-methyl pyrrolidone (NMP). The method comprises the following steps: (1) introducing industrial-grade N-methyl pyrrolidone into a batch rectifying tower; (2) introducing the tower kettle produced liquid into a resin adsorption tower at a certain flow rate; (3) introducing the discharged material of the resin adsorption tower into a dehydrating tower; (4) introducing the material discharged from the dehydrating tower into a sub-boiling distillation tower; and (5) collecting the discharged material, and carrying out membrane filtration to obtain the electronic-grade N-methyl pyrrolidone. The method provided by the invention is flexible to operate, low in energy consumption, short in flow and good in purification effect, the ion exchange resin and the molecular sieve can be regenerated and reused, and more than or equal to 99.99% of G4-grade N-methyl pyrrolidone can be obtained.

Description

Technical Field

[0001] The invention belongs to the technical field of electronic chemical purification, and in particular relates to a method for coupling purification of electronic grade N-methylpyrrolidone (NMP). Background Art

[0002] N-methylpyrrolidone (NMP) is a polar solvent with extremely strong solubility and is widely used in the electronics industry, especially in industries such as integrated circuits and hard disks that require strict control of metal ions and microparticles. In addition, the positive electrode material of new energy lithium batteries usually uses polyvinylidene fluoride (PVDF) as a binder, and NMP is the key solvent for dissolving PVDF. As a binder solvent used in the coating production of lithium battery positive electrode materials, its quality directly affects the quality of lithium-ion battery slurry coating and the requirements for environmental protection. In the semiconductor chip manufacturing process, the wafer needs to be cleaned to remove organic and inorganic pollutants attached to the surface. After the photolithography process, the residue of photoresist will affect the subsequent processing and final performance of the chip, and NMP can effectively dissolve and remove these residues. With the rapid development of the new energy lithium battery field and the semiconductor field, the market demand for electronic grade NMP continues to soar.

[0003] The international ultra-clean high-purity process methods are industry secrets, and there are few literature reports on electronic-grade NMP in China. The existing domestic technology for purifying electronic-grade NMP is mainly distillation, but there will still be a certain amount of metal impurity ions and moisture in the product, which is difficult to meet higher-level electronic chemical standards. In 2023, the output of my country's NMP industry has reached 1.7407 million tons, and electronic-grade NMP accounts for as high as 96.51%. The purity of most electronic-grade NMP is 99.9%. The market demand for higher-standard electronic-grade NMP is increasing.

[0004] In 2009, CN 101508667A "A method for purifying N-methylpyrrolidone" adopts a three-tower distillation method of mixing a water-blocking agent, a strong base and a weak acid sodium salt, and NMP and injecting them into a deamination tower, a dehydration tower, and a distillation tower to obtain electronic-grade NMP. However, the electronic-grade NMP in this patent has high metal impurity ion and water content, and its purity cannot meet today's electronic chemical standards.

[0005] In 2023, CN 117327001A "A method for purifying electronic grade NMP" prepared a homemade MOF mixed resin to adsorb metal impurities in NMP to obtain electronic grade NMP. However, the regeneration effect of the resin in this method is poor, and the method for removing organic impurities and moisture is not described. Summary of the invention

[0007] In order to solve the above technical problems, the present invention adopts a distillation-adsorption-sub-boiling distillation-membrane separation coupled purification method for producing electronic grade NMP, which has flexible operation, low energy consumption, short process, good purification effect, and ion exchange resin and molecular sieve can be regenerated and reused.

[0008] The present invention is achieved through the following technical solutions:

[0009] (1) passing industrial grade N-methylpyrrolidone into a batch distillation tower at room temperature and pressure; the reflux ratio of the batch distillation tower is 0.1-10, and the operation time is 0.1-8 hours;

[0010] (2) passing the produced liquid from the tower bottom into the resin adsorption tower at a flow rate of 0.5 mL / min-1000 mL / min;

[0011] (3) passing the discharge from the resin adsorption tower into a dehydration tower;

[0012] (4) passing the discharge from the dehydration tower into a sub-boiling distillation tower; the operating temperature of the sub-boiling distillation tower is 100° C.-250° C.;

[0013] (5) Collect the discharged material and filter it through a membrane to obtain electronic grade NMP.

[0014] In the above technical solution, preferably, the reflux ratio of the intermittent distillation tower described in step (1) is 0.5-5. Within this range, it can be ensured that the distillation has the best separation effect under the premise of minimizing energy consumption. Limiting the reflux ratio range enhances the purification effect of the present invention on NMP and reduces the content of water, organic impurities and impurity ions in NMP. When the reflux ratio is too large or too small, the purification effect of the present invention will be reduced.

[0015] In the above technical solution, preferably, the operation time of the intermittent distillation tower described in step (1) is 2-4 hours. In the present invention, the time is limited to 0.1-8 hours, preferably 2-4 hours, which can ensure that the distillation has the best separation effect in the shortest possible time, strengthen the purification effect of the present invention on NMP, reduce energy consumption, shorten the process, and improve efficiency. When the distillation time is too long or too short, the energy consumption and process of the present invention will be increased, and the efficiency will be reduced.

[0016] In the above technical solution, the ion exchange resin in the resin adsorption tower described in step (2) is selected from any one of BPC-100, BPC500, BPX-6150, and BPA-5BG. The present invention unconventionally selects the above ion exchange resin, which has excellent adsorption effect on metal ions.

[0017] In the above technical scheme, the ion adsorption amount described in step (2) is 0.1-1000g, preferably 300-900g. The present invention limits the ion adsorption amount to 0.1-1000g, preferably 300-900g, which can ensure that the present invention simplifies the resin amount under the premise of achieving the adsorption effect, strengthens the purification effect of NMP of the present invention and simplifies the resin cost. When the resin amount is too high or too low, the purification effect of the present invention will be reduced and the cost will increase.

[0018] In the above technical scheme, it is preferred that the flow rate of the NMP described in step (2) entering the resin adsorption tower is 0.5mL / min-1000mL / min, preferably 5mL / min-100mL / min. Within the above range, it can be ensured that the present invention shortens the adsorption time under the premise of achieving the adsorption effect, strengthens the adsorption effect of the present invention on the NMP impurity ion and shortens the adsorption time. When the flow rate is too high or too low, it will cause the purification effect of the present invention to decrease, the time cost to increase, and the efficiency to decrease.

[0019] In the above technical solution, the molecular sieve in the dehydration tower described in step (3) is selected from any one of 3A molecular sieve, 4A molecular sieve and 5A molecular sieve.

[0020] In the above technical scheme, the amount of molecular sieve in the dehydration tower described in step (3) is 0.1-1000g, preferably in the range of 50-200g. The present invention limits the amount of molecular sieve to 0.1-1000g, preferably in the range of 50-200g, which can ensure that the present invention simplifies the amount of molecular sieve under the premise of achieving the adsorption effect, strengthens the water adsorption effect of the present invention on NMP and simplifies the cost of molecular sieve. When the amount of molecular sieve is too much or too little, the dehydration effect of the present invention will be reduced and the cost will increase.

[0021] In the above technical solution, preferably, the operating temperature of the sub-boiling distillation tower in step (4) is 100°C-250°C, preferably 150°C-220°C. Within the above range, the present invention can obtain the best separation effect in the shortest time and the best trace metal ion removal effect in the shortest time. When the sub-boiling distillation temperature is too high or too low, the effect of the present invention on the removal of trace metal ions will be weakened and the operation time will be increased.

[0022] The purity of the industrial grade NMP in the present invention is 99%, the content of metal impurity ions is above 100000ppt, and the water content is 8476.8ppm. (See the table of embodiments for details)

[0023] In the above technical solution, the metal impurity ion content in the electronic grade NMP described in step (5) is 1ppt-100ppt, the water content is 10ppm-1000ppm, the number of solid particles with a particle size of 0.1μm or more is ≤50ea / mL, and the purity is ≥99.99%.

[0024] The domestic production method of electronic grade NMP is mainly continuous distillation. The present invention creatively combines purification steps such as adsorption resin, molecular sieve, sub-boiling distillation and membrane filtration with intermittent distillation. In addition, compared with continuous distillation, intermittent distillation also has the characteristics of flexible operation, low energy consumption and short process.

[0025] In the prior art, the electronic grade NMP is mainly of G1-G3 grade, and the NMP obtained by the present invention can reach G4 grade or above, with the metal impurity ion content less than or equal to 10ppt and the impurity particle size less than 0.1μm.

[0026] The present invention replaces the traditional continuous distillation with intermittent distillation, which has the characteristics of flexible operation, low energy consumption and short process. The resin adsorption tower and dehydration tower are easy to install and have good purification effect. Figure 3 .

[0027] The method provided by the present invention has the advantages that the intermittent distillation tower is flexible in operation and has low energy consumption, the resin adsorption tower and the dehydration tower are easy to install and have good purification effect, and the ion exchange resin and the molecular sieve can be regenerated and reused, and still have good adsorption effect after 5 times of adsorption and desorption. The sub-boiling distillation tower can further remove trace impurity ions in NMP to obtain electronic grade NMP with extremely low content of metal impurity ions. The filter membrane can control the content of solid impurity particles at an extremely low level, and the product purity is ≥99.99%. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The present invention is a flow chart of the equipment of the method for purifying electronic grade N-methylpyrrolidone.

[0029] Among them: 1-distillation tower; 2-resin adsorption tower; 3-dehydration tower; 4-sub-boiling distillation tower; 5-membrane filtration; 6-pump.

[0030] Figure 2 For ion exchange resins BPC-100, BPC500, BPX-6150, BPA-5BG to metal impurity ions (Na + and Ni 2+ The adsorption amount of the sample (as an example) varies with the adsorption time.

[0031] Figure 3 This is a graph showing the regeneration results of the ion exchange resin and molecular sieve of the present invention. (Ion exchange resin: BPC-100; molecular sieve: HYDRANAL 4A molecular sieve) DETAILED DESCRIPTION

[0032] The technical solution of the present invention will be clearly and completely described in conjunction with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0033] Example 1

[0034] (1) passing industrial grade N-methylpyrrolidone into a batch distillation tower with a reflux ratio of 2 and a distillation time of 3 h;

[0035] (2) The produced liquid from the bottom of the tower was passed into the resin adsorption tower at 20 mL / min, and BPC-100 ion exchange resin was added to the bed. The resin dosage was 600 g, and the NMP breakthrough time was 3.5 h;

[0036] (3) The output of the resin adsorption tower was passed into a dehydration tower, and 120 g of 4A molecular sieve was added to the bed;

[0037] (4) The output of the dehydration tower is passed into the sub-boiling distillation tower, and the distillation temperature in the tower is set to 180°C

[0038] (5) Collect the discharged material and filter it through a membrane to obtain electronic grade NMP. For ease of description and comparison, the test results of the content of each component in electronic grade NMP are listed in the following table.

[0039] Example 2

[0040] (1) passing industrial grade N-methylpyrrolidone into a batch distillation tower with a reflux ratio of 0.5 and a distillation time of 2 h;

[0041] (2) The produced liquid from the tower bottom was passed into the resin adsorption tower at 20 mL / min, and BPC-100 ion exchange resin was added to the bed. The resin dosage was 600 g, and the NMP breakthrough time was 3.6 h;

[0042] (3) The output of the resin adsorption tower was passed into a dehydration tower, and 120 g of 4A molecular sieve was added to the bed;

[0043] (4) The output of the dehydration tower is passed into the sub-boiling distillation tower, and the distillation temperature in the tower is set to 180°C

[0044] (5) Collect the discharged material and filter it through a membrane to obtain electronic grade NMP. For ease of description and comparison, the test results of the content of each component in electronic grade NMP are listed in the following table.

[0045] Example 3

[0046] (1) passing industrial grade N-methylpyrrolidone into a batch distillation tower with a reflux ratio of 5 and a distillation time of 4 h;

[0047] (2) The produced liquid from the bottom of the tower was passed into the resin adsorption tower at 20 mL / min, and BPC-100 ion exchange resin was added to the bed. The resin dosage was 600 g, and the NMP breakthrough time was 3.5 h;

[0048] (3) The output of the resin adsorption tower was passed into a dehydration tower, and 120 g of 4A molecular sieve was added to the bed;

[0049] (4) The output of the dehydration tower is passed into the sub-boiling distillation tower, and the distillation temperature in the tower is set to 180°C

[0050] (5) Collect the discharged material and filter it through a membrane to obtain electronic grade NMP. For ease of description and comparison, the test results of the content of each component in electronic grade NMP are listed in the following table.

[0051] Example 4

[0052] (1) passing industrial grade N-methylpyrrolidone into a batch distillation tower with a reflux ratio of 2 and a distillation time of 3 h;

[0053] (2) The produced liquid from the bottom of the tower was passed into the resin adsorption tower at 100 mL / min, and BPC-100 ion exchange resin was added to the bed. The resin dosage was 300 g, and the NMP breakthrough time was 1.1 h;

[0054] (3) The output of the resin adsorption tower was passed into a dehydration tower, and 50 g of 4A molecular sieve was added to the bed;

[0055] (4) The output of the dehydration tower is passed into the sub-boiling distillation tower, and the distillation temperature in the tower is set to 180°C

[0056] (5) Collect the discharged material and filter it through a membrane to obtain electronic grade NMP. For ease of description and comparison, the test results of the content of each component in electronic grade NMP are listed in the following table.

[0057] Example 5

[0058] (1) passing industrial grade N-methylpyrrolidone into a batch distillation tower with a reflux ratio of 2 and a distillation time of 3 h;

[0059] (2) The produced liquid from the tower bottom was passed into the resin adsorption tower at 5 mL / min, and BPC-100 ion exchange resin was added to the bed. The resin dosage was 900 g, and the NMP breakthrough time was 5.8 h;

[0060] (3) The output of the resin adsorption tower was passed into a dehydration tower, and 80 g of 4A molecular sieve was added to the bed;

[0061] (4) The output of the dehydration tower is passed into the sub-boiling distillation tower, and the distillation temperature in the tower is set to 180°C

[0062] (5) Collect the discharged material and filter it through a membrane to obtain electronic grade NMP. For ease of description and comparison, the test results of the content of each component in electronic grade NMP are listed in the following table.

[0063] Example 6

[0064] (1) passing industrial grade N-methylpyrrolidone into a batch distillation tower with a reflux ratio of 2 and a distillation time of 3 h;

[0065] (2) The produced liquid from the bottom of the tower was passed into the resin adsorption tower at 20 mL / min, and BPA-5BG ion exchange resin was added to the bed. The resin dosage was 600 g, and the NMP breakthrough time was 2.7 h;

[0066] (3) The output from the resin adsorption tower was passed into a dehydration tower, and 200 g of 4A molecular sieve was added to the bed;

[0067] (4) The output of the dehydration tower is passed into the sub-boiling distillation tower, and the distillation temperature in the tower is set to 180°C

[0068] (5) Collect the discharged material and filter it through a membrane to obtain electronic grade NMP. For ease of description and comparison, the test results of the content of each component in electronic grade NMP are listed in the following table.

[0069] Example 7

[0070] (1) passing industrial grade N-methylpyrrolidone into a batch distillation tower with a reflux ratio of 2 and a distillation time of 3 h;

[0071] (2) The produced liquid from the bottom of the tower was passed into the resin adsorption tower at 20 mL / min, and BPC-100 ion exchange resin was added to the bed. The resin dosage was 600 g, and the NMP breakthrough time was 3.5 h;

[0072] (3) The output of the resin adsorption tower was passed into a dehydration tower, and 120 g of 3A molecular sieve was added to the bed;

[0073] (4) The output of the dehydration tower is passed into the sub-boiling distillation tower, and the distillation temperature in the tower is set to 180°C

[0074] (5) Collect the discharged material and filter it through a membrane to obtain electronic grade NMP. For ease of description and comparison, the test results of the content of each component in electronic grade NMP are listed in the following table.

[0075] Example 8

[0076] (1) passing industrial grade N-methylpyrrolidone into a batch distillation tower with a reflux ratio of 2 and a distillation time of 3 h;

[0077] (2) The produced liquid from the bottom of the tower was passed into the resin adsorption tower at 20 mL / min, and BPC-100 ion exchange resin was added to the bed. The resin dosage was 600 g, and the NMP breakthrough time was 3.5 h;

[0078] (3) The output of the resin adsorption tower was passed into a dehydration tower, and 120 g of 5A molecular sieve was added to the bed;

[0079] (4) The output of the dehydration tower is passed into the sub-boiling distillation tower, and the distillation temperature in the tower is set to 180°C

[0080] (5) Collect the discharged material and filter it through a membrane to obtain electronic grade NMP. For ease of description and comparison, the test results of the content of each component in electronic grade NMP are listed in the following table.

[0081] Example 9

[0082] (1) passing industrial grade N-methylpyrrolidone into a batch distillation tower with a reflux ratio of 2 and a distillation time of 3 h;

[0083] (2) The produced liquid from the bottom of the tower was passed into the resin adsorption tower at 20 mL / min, and BPC-100 ion exchange resin was added to the bed. The resin dosage was 600 g, and the NMP breakthrough time was 3.5 h;

[0084] (3) The output of the resin adsorption tower was passed into a dehydration tower, and 120 g of 4A molecular sieve was added to the bed;

[0085] (4) The output of the dehydration tower is passed into a sub-boiling distillation tower, and the distillation temperature in the tower is set to 150°C

[0086] (5) Collect the discharged material and filter it through a membrane to obtain electronic grade NMP. For ease of description and comparison, the test results of the content of each component in electronic grade NMP are listed in the following table.

[0087] Example 10

[0088] (1) passing industrial grade N-methylpyrrolidone into a batch distillation tower with a reflux ratio of 2 and a distillation time of 3 h;

[0089] (2) The produced liquid from the bottom of the tower was passed into the resin adsorption tower at 20 mL / min, and BPC-100 ion exchange resin was added to the bed. The resin dosage was 600 g, and the NMP breakthrough time was 3.5 h;

[0090] (3) The output of the resin adsorption tower was passed into a dehydration tower, and 120 g of 4A molecular sieve was added to the bed;

[0091] (4) The output of the dehydration tower is passed into the sub-boiling distillation tower, and the distillation temperature in the tower is set to 220°C

[0092] (5) Collect the discharged material and filter it through a membrane to obtain electronic grade NMP. For ease of description and comparison, the test results of the content of each component in electronic grade NMP are listed in the following table.

[0093]

[0094]

[0095] 1. Ion exchange resin regeneration experiment: Take an appropriate amount of BPC-100 and place it in the resin column. Wash it with ultrapure water until the eluate is clear; elute the resin with 8 times the volume of NaOH solution (1 mol / L) for 30 minutes to ensure that there are no bubbles in the resin layer; elute the resin with 8 times the volume of ultrapure water for 30 minutes; repeat the above steps with 8 times the volume of HCl solution (1 mol / L); elute the resin with ultrapure water until the eluate is neutral.

[0096] 2. Molecular sieve desorption regeneration experiment: wash with water, dry in an oven, preheat in a muffle furnace for about 1.5 hours, heat to 350℃ for 5 hours, 550℃ for 3 hours, heat intermittently, cool naturally to 100-200℃, then take it out of the furnace and use it again.

[0097] The results of the regeneration experiment are as follows Figure 3 .

[0098] The specific embodiments described above further illustrate the purpose, technical solutions and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for coupling purification of electronic grade NMP, characterized in that, The following steps are involved: (1) passing industrial grade N-methylpyrrolidone into a batch distillation tower at room temperature and pressure, wherein the reflux ratio of the batch distillation tower is 0.1-10 and the operation time is 0.1-8 hours; (2) passing the produced liquid from the tower bottom into the resin adsorption tower at a flow rate of 0.5 mL / min-1000 mL / min; (3) passing the discharge from the resin adsorption tower into a dehydration tower; (4) passing the discharge from the dehydration tower into a sub-boiling distillation tower; the operating temperature of the sub-boiling distillation tower is 100° C.-250° C.; (5) Collect the discharged material and filter it through a membrane to obtain electronic grade NMP.

2. The method for purifying electronic grade NMP according to claim 1, wherein The reflux ratio of the intermittent distillation tower is 0.5-5.

3. The method for purifying electronic grade NMP according to claim 2, wherein The operation time of the intermittent distillation tower is 2-4 hours.

4. The method for purifying electronic grade NMP according to claim 1, wherein The resin exchange resin in the resin adsorption tower is selected from any one of BPC-100, BPC500, BPX-6150 and BPA-5BG.

5. The method for purifying electronic grade NMP according to claim 4, wherein The dosage of the ion exchange resin is 0.1-1000g.

6. The method for purifying electronic grade NMP according to claim 4, wherein The flow rate of the NMP entering the resin adsorption tower is 5-100 mL / min.

7. The method for purifying electronic grade NMP according to claim 1, wherein The molecular sieve in the dehydration tower is selected from any one of 3A molecular sieve, 4A molecular sieve and 5A molecular sieve.

8. The method for purifying electronic grade NMP according to claim 7, wherein The dosage of the molecular sieve in the dehydration tower is 0.1-1000g.

9. The method for purifying electronic grade NMP according to claim 1, wherein The operating temperature of the sub-boiling distillation tower is 150°C-220°C.

10. An electronic grade NMP, characterized in that The electronic grade NMP purified by the method described in any one of claims 1 to 9 has a metal impurity ion content of 1 ppt-100 ppt, a water content of 10 ppm-1000 ppm, a number of solid particles with a particle size of 0.1 μm or more ≤50 ea / mL, and a purity of ≥99.99%.

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