Electronic-grade citric acid production process based on extraction coupling crystallization

Abstract

The invention relates to an electronic-grade citric acid production process based on combination of extraction and ion exchange resin, which comprises the following steps: adding an extraction agent into an industrial-grade citric acid solution with higher impurity content for pretreatment, adsorbing part of metal impurities in the citric acid solution, and performing two-phase separation after the extraction is completed, an organic extraction phase obtained through separation is regenerated and reused; and removing the residual extractant and main metal impurities from the citric acid purified liquid obtained by separation through a resin column, carrying out vacuum concentration, and carrying out cooling crystallization to obtain the electronic-grade citric acid solid. The process is high in production efficiency, simple in equipment and suitable for industrial popularization.

Description

Technical Field

[0001] The invention relates to the technical field of chemical industry, and in particular to a production process of electronic grade citric acid based on extraction coupled crystallization. Background Art

[0002] As a key fine chemical raw material, electronic grade citric acid plays a vital role in modern industry, especially in the electronics manufacturing and semiconductor industries. Due to its unique chemical properties, high-purity citric acid is widely used in these fields in key processes such as cleaning, etching and polishing to ensure the surface quality and functionality of electronic components and semiconductor materials. High-purity citric acid can effectively remove impurities and metal ions, thereby avoiding the potential negative impact of these impurities on the performance of electronic products. Therefore, the purity of electronic grade citric acid is directly related to the quality and reliability of the final product, and is crucial to improving the performance of electronic and semiconductor products.

[0003] In the production process of electronic-grade citric acid, the removal of metal impurities is a key step to ensure the high purity of the product. Traditionally, this process mainly relies on physical and chemical methods such as precipitation and filtration. Although these methods are able to remove metal impurities to a certain extent, they have some significant limitations. First, the precipitation process often requires the use of a large amount of chemical reagents, which not only increases the processing cost, but also may produce a large amount of chemical waste, which has a negative impact on the environment. Secondly, the filtration process may be inefficient, especially for the removal of trace metal ions, which may result in insufficient product purity to meet the high standards required by the electronics manufacturing and semiconductor industries. In addition, these traditional methods often require multiple treatments to achieve the required purity level, further increasing production costs and time. Therefore, the development of more efficient, cost-effective and environmentally friendly metal removal technologies is crucial for the production of electronic-grade citric acid. Summary of the invention

[0004] In view of the problems of low purity, low production efficiency, high energy consumption and complex technical route of citric acid in the prior art, the present invention provides a simple and efficient method for preparing electronic grade citric acid.

[0005] To achieve the purpose of the present invention, the present invention adopts the following technical solutions: A production process of electronic grade citric acid based on extraction coupled crystallization comprises the following steps: S1: Add industrial-grade solid citric acid and ultrapure water into a dissolution tank to prepare a citric acid stock solution of a certain concentration.

[0006] S2: Mix the extractant and the diluent according to a set ratio.

[0007] S3: Add citric acid stock solution and organic extractant in a certain proportion for extraction, set the temperature, stirring rate, and extraction times, and after the mixed solution is extracted, separate the water phase and the oil phase.

[0008] S4: regenerating the organic extractant obtained after separation in step S3 and retaining it for later use.

[0009] S5: The purified citric acid solution 1 obtained after separation in step S3 is injected into a two-stage series resin purification device, wherein the first-stage resin column is filled with a macroporous adsorption resin to remove the residual organic extractant in the purified citric acid solution to obtain a purified citric acid solution 2; and the second-stage resin column is filled with a strong acid cationic resin to remove the residual metal impurities in the purified citric acid solution 2 to obtain a purified citric acid solution 3.

[0010] S6: The purified citric acid solution 3 obtained in step S5 is concentrated under reduced pressure.

[0011] S7: Cooling and crystallizing the citric acid concentrate obtained in step S6.

[0012] S8: performing solid-liquid separation and crystal elution on the crystal slurry obtained in step S7 to obtain citric acid wet crystals.

[0013] S9: Dry the wet crystals obtained in step S8 and store them.

[0014] Furthermore, the mass concentration of the citric acid stock solution in step S1 is not higher than 45%.

[0015] The mass concentration of the citric acid stock solution in step S1 is not higher than 15%-45%, and the citric acid stock solution contains anionic impurities and cationic impurities, wherein the anionic impurities include at least one of nitrate, sulfate, phosphate, and chloride, and the content of each anionic impurity is between 200ppb-1000ppb; the cationic impurities include Zn, Cu, Ni, Co, Fe, Ca, K, Mg, Na, Li, etc., and the content of each cationic impurity is between 10ppb-4000ppb, and the TOC content is 20-50ppm.

[0016] Furthermore, in step S2, the extracting agent is D2EHPA and LIX84-I, and the diluent is kerosene.

[0017] Furthermore, in step S3, the extraction temperature is 20-50° C., and the stirring speed is 50-200 rpm. If the temperature is too high or the stirring speed is too fast, emulsification may occur easily.

[0018] Furthermore, the regeneration method of the extractant in step S4 is to add 0.5-4 times the volume of 2 mol / L sulfuric acid solution to the organic extractant obtained after separation in S3, stir for 5-30 minutes for stripping, and repeat washing twice.

[0019] Furthermore, in step S5, the resin filled in the resin column 1 is any one of NKA-9, NKA-Ⅱ, D4020, D4006, H103, D101B, and D3520, and the column flow rate is 2-10 Bv / h.

[0020] Furthermore, the resin used in the resin column 2 in step S5 is a strongly acidic cationic resin, preferably any one of C100E, UCW3700, ZGC107, 001x10H, HZ-016, D001AM, and D001MB, and the column flow rate is 2-10 Bv / h.

[0021] Furthermore, in step S6, the vacuum degree is -0.09 MPa, the heating temperature is 50-80° C., and the concentration is to a mass fraction of 60-70%.

[0022] Furthermore, in the step S7, the temperature point for adding the seed crystal is set at 25-29°C. When the solution temperature is higher than 25-29°C, it is the first cooling stage, and the cooling rate is fast, which is 0.1-1°C / min; the cooling process after adding the seed crystal is the second cooling stage, and the cooling rate is slow, which is 0.01-0.05°C / min, and the cooling end temperature is 10-20°C; the third stage is the aging stage, and the temperature is the set crystallization end temperature of 10-20°C, and the constant temperature time is 2h. Among them, the seed crystal addition amount is 0.5-10%, and the seed crystal size is 40-60 mesh.

[0023] Furthermore, in step S8, the crystal slurry is centrifuged at a rotation speed of 3000-4000 rpm for 3-5 minutes to separate the mother liquor to obtain wet crystals, and then sprayed with ultrapure water with a wet crystal mass fraction of 5-10% and centrifuged to obtain pure citric acid crystals.

[0024] Furthermore, in step S8, the drying temperature is 45-65°C.

[0025] Based on the above technical solution, the present invention also provides an electronic-grade citric acid, the electronic-grade citric acid prepared by the production process, wherein the content of each anion in the electronic-grade citric acid is less than 10 ppb, more preferably less than 8 ppb, more preferably less than 6 ppb, and more preferably less than 5 ppb; the anion includes at least one of nitrate, sulfate, phosphate, and chloride; The content of each anion in the electronic grade citric acid is less than 10 ppb, more preferably less than 8 ppb, more preferably less than 5 ppb, and more preferably less than 1 ppb; The cationic impurities include Zn, Cu, Ni, Co, Fe, Ca, K, Mg, Na, Li, etc.

[0026] The present invention provides an electronic grade citric acid production process based on extraction coupled crystallization, which has the following beneficial effects: Improve purity: The present invention purifies industrial-grade citric acid through the process of extraction coupling crystallization, effectively removes metal ion impurities and other organic impurities in industrial-grade citric acid, and finally obtains electronic-grade citric acid with high purity, which can meet the electronic-grade standard and meet the semiconductor industry's demand for high-purity chemical reagents. Simplify the process route: The production process route of the present invention is relatively simple. First, the metal ion impurities in the industrial-grade citric acid solution are extracted by extraction technology, and then the residual organic extractant is adsorbed by a macroporous adsorption resin. Finally, the obtained primary citric acid purified liquid is concentrated, crystallized, centrifuged, and dried to obtain an electronic-grade citric acid solid. Compared with the existing chemical synthesis method, the process route of the present invention is simpler and easier to operate. Reduce production costs: The production process of the present invention is relatively simple, requires less equipment, and has mild reaction conditions and is easy to control, which all help to reduce production costs. In addition, since the process route of the present invention is simple and has high production efficiency, it can also reduce production costs to a certain extent. Realize industrial production: The production process of the present invention is relatively simple, easy to operate and control, and suitable for large-scale production. Therefore, the present invention provides the possibility for the industrial production of electronic-grade citric acid, which helps to promote the development of the semiconductor industry. Environmental protection: In the production process of the present invention, the extractant and the citric acid mother liquor enriched with impurities and the washing liquid can be recycled, and a large amount of waste and wastewater will not be generated, which is environmentally friendly. In general, compared with the prior art, the present invention has the advantages of high purity, simple process, low cost, easy industrial production, and environmental protection, and is expected to be widely used in the semiconductor industry. Figure 1 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0027] Embodiment 1: S1: Add industrial-grade solid citric acid and ultrapure water into a reactor to dissolve and prepare a citric acid stock solution with a mass concentration of 30%.

[0028] S2: Prepare a 30% Lix84-I / kerosene extraction system in a blender.

[0029] S3: Add 30% citric acid stock solution and 30% Lix84-I / kerosene in a ratio of 1:2 (oil phase:water phase) into a constant temperature stirrer 2, set the temperature to 40°C, stir at a rate of 100 rpm, and mix thoroughly for 10 minutes. After the mixed solution is extracted, pour it into a separatory funnel to separate the water phase (i.e., citric acid purified solution 1) and the oil phase, and repeat the extraction twice.

[0030] S4: Add 2 mol / L sulfuric acid solution to the oil phase obtained after separation in S3, i.e., the organic extractant, at a ratio of 1:1, and stir for 10 min for stripping. Repeat the washing twice, and keep the regenerated extractant for later use.

[0031] S5: The purified citric acid solution 1 obtained after separation in S3 is injected into a secondary series of resin columns, wherein the primary resin column uses a macroporous adsorption resin D101B to remove the residual organic extractant in the citric acid solution to obtain a purified citric acid solution 2; the secondary resin column uses a strong acid cationic resin C100E to remove the residual metal ion impurities in the citric acid solution to obtain a purified citric acid solution 3.

[0032] S6: The purified citric acid solution 3 obtained in S5 is concentrated at a vacuum degree of -0.09 MPa and a heating temperature of 80° C. until the mass fraction of the solution is 65%.

[0033] S7: The citric acid concentrate obtained in S6 is cooled and crystallized. The cooling rate in the first stage is 0.2°C / min. When the temperature drops to 29°C, 0.5% of seed crystals are added. The cooling rate in the second stage is 0.03°C / min. The temperature is dropped to 20°C and kept at a constant temperature for 2h.

[0034] S8: The crystal slurry obtained in S7 is transferred to a centrifuge for solid-liquid separation. The centrifuge speed is 4000 rpm. After centrifugation for 5 minutes, ultrapure water with a wet crystal mass fraction of 10% is sprayed and centrifuged for 5 minutes to obtain pure citric acid crystals.

[0035] S9: Dry the wet crystals obtained in S8 at 45° C. and store them.

[0036]

[0037] Embodiment 2: S1: Add industrial-grade solid citric acid and ultrapure water into a reactor to dissolve and prepare a citric acid stock solution with a mass concentration of 35%.

[0038] S2: Prepare a 30% D2EHPA / kerosene extraction system in a blender.

[0039] S3: Add 35% citric acid stock solution and 30% D2EHPA / kerosene in a ratio of 1:1 (oil phase: water phase) into the thermostatic stirrer 2, set the temperature to 45°C, stir at a rate of 160 rpm, mix thoroughly for 20 min, and after the mixed solution is extracted, pour it into a separatory funnel to separate the water phase (i.e., citric acid purified solution 1) and the oil phase, and repeat the extraction twice.

[0040] S4: Add 2 mol / L sulfuric acid solution to the oil phase obtained after separation in S3, i.e., the organic extractant, at a ratio of 1:1, and stir for 10 min for stripping. Repeat the washing twice, and keep the regenerated extractant for later use.

[0041] S5: The purified citric acid solution 1 obtained after separation in S3 is injected into a secondary series of resin columns, wherein the primary resin column uses a macroporous adsorption resin D4006 to remove the residual organic extractant in the citric acid solution to obtain a purified citric acid solution 2; the secondary resin column uses a strong acid cationic resin D001AM to remove the residual metal impurities in the citric acid solution to obtain a purified citric acid solution 3.

[0042] S6: The purified citric acid solution 3 obtained in S5 is concentrated at a vacuum degree of -0.09 MPa and a heating temperature of 60° C. until the mass fraction of the solution is 67%.

[0043] S7: The citric acid concentrate obtained in S6 is cooled and crystallized. The cooling rate of the first stage is 0.4°C / min. When the temperature drops to 29°C, 4% of seed crystals are added. The cooling rate of the second stage is 0.02°C / min. The temperature is dropped to 15°C and kept at a constant temperature for 2h.

[0044] S8: The crystal slurry obtained in S7 is transferred to a centrifuge for solid-liquid separation. The centrifuge speed is 4000 rpm. After centrifugation for 5 minutes, ultrapure water with a wet crystal mass fraction of 10% is sprayed and centrifuged for 5 minutes to obtain pure citric acid crystals.

[0045] S9: Dry the wet crystals obtained in S8 at 50° C. and store them.

[0046]

[0047] Embodiment 3: S1: Add industrial-grade solid citric acid and ultrapure water into a reactor to dissolve and prepare a citric acid stock solution with a mass concentration of 40%.

[0048] S2: Prepare an extraction system of 15% Lix84-I + 15% D2EHPA / kerosene in a blender.

[0049] S3: Add 40% citric acid stock solution and 15% Lix84-I + 15% D2EHPA / kerosene in a ratio of 2:1 (oil phase: water phase) into the thermostatic stirrer 2, set the temperature to 45°C, stir at a rate of 200 rpm, mix thoroughly for 20 minutes, and after the mixed solution is extracted, pour it into a separatory funnel to separate the water phase (i.e., citric acid purified solution 1) and the oil phase, and repeat the extraction twice.

[0050] S4: Add 2 mol / L sulfuric acid solution to the oil phase obtained after separation in S3, i.e., the organic extractant, at a ratio of 1:1, and stir for 20 minutes for back extraction. Repeat the washing twice, and keep the regenerated extractant for later use.

[0051] S5: The purified citric acid solution 1 obtained after separation in S3 is injected into three-stage series resin columns, wherein the first-stage resin column uses macroporous adsorption resin NKA-9 to remove the residual organic extractant in the citric acid solution to obtain purified citric acid solution 2; the second-stage resin column uses strong acid cationic resin UCW3700 to remove the residual metal impurities in the citric acid solution to obtain purified citric acid solution 3.

[0052] S6: The purified citric acid solution 3 obtained in S5 is concentrated at a vacuum degree of -0.09 MPa and a heating temperature of 70° C. until the mass fraction of the solution is 69%.

[0053] S7: The citric acid concentrate obtained in S6 is cooled and crystallized. The cooling rate in the first stage is 0.6°C / min. When the temperature drops to 29°C, 8% of seed crystals are added. The cooling rate in the second stage is 0.04°C / min. The temperature is dropped to 18°C ​​and kept at a constant temperature for 2h.

[0054] S8: The crystal slurry obtained in S7 is transferred to a centrifuge for solid-liquid separation. The centrifuge speed is 4000 rpm. After centrifugation for 5 minutes, ultrapure water with a wet crystal mass fraction of 10% is sprayed and centrifuged for 5 minutes to obtain pure citric acid crystals.

[0055] S9: Dry the wet crystals obtained in S8 at 55° C. and store them.

[0056]

Claims

1. A process for producing electronic grade citric acid based on extraction coupled crystallization, comprising the following steps: S1: Add industrial-grade solid citric acid and ultrapure water into a dissolution tank to prepare a citric acid stock solution of a certain concentration; S2: Mixing the extractant and the diluent according to a set ratio; S3: adding citric acid stock solution and organic extractant in a certain proportion for extraction, setting the temperature, stirring rate, and extraction times, and after the mixed solution is extracted, separating the aqueous phase and the oil phase to obtain a purified citric acid solution 1; S4: injecting the purified citric acid solution 1 obtained after separation in step S3 into a primary resin column and a secondary resin column in sequence for purification; The primary resin column is filled with a macroporous adsorption resin to remove the residual organic extractant in the citric acid purified solution to obtain a citric acid purified solution 2; the secondary resin column is filled with a strong acid cationic resin to remove the residual metal impurities in the citric acid purified solution 2 to obtain a citric acid purified solution 3; S6: The purified citric acid solution 3 obtained in step S5 is concentrated under reduced pressure, cooled and crystallized, separated, washed and dried to obtain electronic grade citric acid.

2. The process for producing electronic grade citric acid based on extraction coupled crystallization according to claim 1, characterized in that: The mass concentration of the citric acid stock solution in step S1 is 15% to 45%, and the citric acid stock solution contains anionic impurities and cationic impurities, wherein the anionic impurities include at least one of nitrate, sulfate, phosphate, and chloride, and the content of each anionic impurity is between 200ppb and 1000ppb; the cationic impurities include Zn, Cu, Ni, Co, Fe, Ca, K, Mg, Na, Li, etc., and the content of each cationic impurity is between 10ppb and 4000ppb, and the TOC content is 20-50ppm.

3. The process for producing electronic grade citric acid based on extraction coupled crystallization according to claim 1, characterized in that: The organic extractant in step S2 contains an extractant and a diluent, wherein the extractant is D2EHPA and LIX84-I, and the diluent is kerosene.

4. The process for producing electronic grade citric acid based on extraction coupled crystallization according to claim 1, characterized in that: In step S3, the extraction temperature is 20-50° C., and the stirring speed is 50-200 rpm.

5. The process for producing electronic grade citric acid based on extraction coupled crystallization according to claim 1, characterized in that: The oil phase separated in step S3 is regenerated and stored for later use; The method for regenerating the extractant in step S4 is to add 0.5-4 times the volume of 2 mol / L sulfuric acid solution to the organic extractant obtained after separation in S3, stir for 5-30 minutes for stripping, and obtain a regenerated catalyst after repeated washing.

6. The process for producing electronic grade citric acid based on extraction coupled crystallization according to claim 1, characterized in that: In the step S4, the resin filled in the primary resin column is any one of NKA-9, NKA-Ⅱ, D4020, D4006, H103, D101B, and D3520, and the column flow rate is 2-10 Bv / h. Furthermore, the resin used in the secondary resin column in step S4 is a strongly acidic cationic resin, preferably any one of C100E, UCW3700, ZGC107, 001x10H, HZ-016, D001AM, and D001MB, and the column flow rate is 2-10 Bv / h.

7. The process for producing electronic grade citric acid based on extraction coupled crystallization according to claim 1, characterized in that: In the step S5, the vacuum degree is -0.09 MPa, the heating temperature is 50-80° C., and the concentration is performed to a mass fraction of 60-70%.

8. The process for producing electronic grade citric acid based on extraction coupled crystallization according to claim 1, characterized in that: In the cooling crystallization process of step S5, 25-29°C is set as the temperature point for adding the seed crystals, when the solution temperature is higher than 25-29°C, it is the first cooling stage, and the cooling rate is 0.1-1°C / min; the cooling process after adding the seed crystals is the second cooling stage, the cooling rate is 0.01-0.05°C / min, and the cooling end temperature is 10-20°C; the third stage is the aging stage, the temperature is 10-20°C, and the constant temperature time is 2-3h; wherein, the amount of seed crystals added is 0.5-10%, and the seed crystal size is 40-60 mesh.

9. The process for producing electronic grade citric acid based on extraction coupled crystallization according to claim 1, characterized in that: In step S5, the crystal slurry is centrifuged at a rotation speed of 3000-4000 rpm for 3-5 minutes to separate the mother liquor to obtain wet crystals, and then sprayed with ultrapure water with a wet crystal mass fraction of 5-10% and centrifuged to obtain pure citric acid crystals; the drying temperature in step S5 is 45-65°C.

10. An electronic grade citric acid, characterized in that: The electronic-grade citric acid prepared by the production process according to any one of claims 1 to 9, wherein the content of each anion in the electronic-grade citric acid is less than 10 ppb, more preferably less than 8 ppb, more preferably less than 6 ppb, and more preferably less than 5 ppb; the anion comprises at least one of nitrate, sulfate, phosphate, and chloride; The content of each anion in the electronic grade citric acid is less than 10 ppb, more preferably less than 8 ppb, more preferably less than 5 ppb, and more preferably less than 1 ppb; The cationic impurities include any one or more combinations of Zn, Cu, Ni, Co, Fe, Ca, K, Mg, Na, and Li.

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