A method for recovering triethylamine, a catalyst in a polycarbonate production process, and application thereof

Abstract

The application discloses a recycling method and application of a catalyst triethylamine in a polycarbonate production process. The recycling method comprises the following steps: S1, adding an inorganic acid aqueous solution into PC oil phase reaction liquid, so that the triethylamine is converted into an ammonium salt and dissolved in a water phase, oil and water are separated, and the water phase is collected; S2, adding lye into the obtained water phase, so that the ammonium salt is re-converted into the triethylamine; S3, performing rectification / stripping on the solution obtained in the step S2, collecting a gas phase on a tower top, and condensing the triethylamine solution; S4, cooling the triethylamine solution in the step S3 to 20 DEG C or below, and filtering to remove solid impurities; S5, adding lye into the filtrate, high-speed mixing to obtain an emulsion, centrifugal separation, and collection of an oil phase, so that the reused triethylamine solution is obtained. According to the recycling method, the reused triethylamine solution obtained can effectively improve / improve heat resistance, powder color, transmittance and the like of the polycarbonate after being reused in the preparation process of the polycarbonate.

Description

TECHNICAL FIELD

[0001] The application relates to a recycling method, in particular to a recycling method of a catalyst triethylamine in a polycarbonate production process and application. BACKGROUND

[0002] Polycarbonate (PC) is an engineering plastic with good comprehensive performance and is widely used in electronic, automobile, building and other industries. High-end polycarbonate is also widely used in the field of optics, which requires not only good mechanical properties but also excellent optical properties and base color. During the processing of polycarbonate, it needs to be injection molded at a high temperature of 300 DEG C or above. During this process, the polycarbonate product is usually yellowed by heat, which affects the optical properties of the polycarbonate. Therefore, it is of great significance to improve the heat resistance and base color of polycarbonate. On the other hand, for polycarbonate products widely used in the field of optics, especially in the field of anti-ultraviolet radiation lenses, the transmittance index is very strict. However, a small amount of impurities in the production process of polycarbonate will greatly affect the transmittance. Therefore, it is crucial to develop advanced polycarbonate production processes to improve the base color, heat resistance and transmittance of the product.

[0003] In the production process of polycarbonate, especially in the synthesis process of phosgene, triethylamine is usually used as a catalyst to speed up the reaction process of interfacial polycondensation. After the interfacial polycondensation reaction, the triethylamine in the PC reaction liquid is recovered and utilized, which not only improves the resource utilization of triethylamine but also reduces its adverse effects on the product. The recovery method of triethylamine is relatively common in the field. Generally, an inorganic acid solution is first added to the PC reaction liquid to convert the amine into an ammonium salt dissolved in the aqueous phase. Then, an alkali solution is added to the aqueous phase to convert the ammonium salt back into amine. Finally, purified triethylamine is obtained by distillation separation.

[0004] However, the present inventors found in their continuous research on the above reaction system that the polycarbonate prepared from the recycled triethylamine generally has significantly reduced product quality, especially in terms of heat stability and base color. It is speculated that a certain amount of impurities affecting the above product quality is produced during the production of polycarbonate or the recycling of triethylamine.

[0005] Patent CN117801254A has conducted in-depth research on the factors affecting the heat resistance of PC and found that the addition of sulfur dioxide can remove impurities including the substance of formula I, thereby improving the heat resistance of PC and improving the product color and light transmittance. However, the present inventors found through small-scale test and verification that this method can only improve the performance of PC powder to a certain extent, and the introduction of sulfur dioxide will be largely retained in the polycarbonate, resulting in poor product crystal point and transmittance.

[0006]

[0007] Therefore, how to obtain the reused triethylamine with high purity and low impurity content, and then improve the product quality of polycarbonate, is still one of the key projects in the field that needs continuous research. SUMMARY

[0008] In order to solve the above technical problems, the present application provides a method for recycling catalyst triethylamine in the production process of polycarbonate and its application.

[0009] The present inventors found in the research that the triethylamine recovery process is usually carried out under high temperature conditions of rectification / stripping, even if the impurities affecting the product performance shown in formula I are removed before rectification / stripping, the industrial polycarbonate produced using the recycled triethylamine as catalyst still has less ideal heat resistance, powder color and transmittance, etc.

[0010] The present inventors found through in-depth research and analysis of the reaction process of triethylamine recovery and recycling that the impurity content shown in formula II is a crucial index affecting the performance of industrial polycarbonate products. The impurity is generated in large quantities in the conventional rectification / stripping process of the triethylamine recovery process. By strictly controlling the content of the impurity, industrial polycarbonate with high heat resistance, powder color and transmittance meeting higher use requirements can be prepared, and an effective solution to control the content of the impurity to 10 ppm or less is proposed, thereby completing the present application.

[0011]

[0012] To achieve the above-mentioned purpose, the technical solution adopted by the present application is as follows:

[0013] A method for recycling catalyst triethylamine in the production process of polycarbonate, comprising the following steps:

[0014] S1, adding an aqueous inorganic acid solution to the PC oil phase reaction liquid to convert triethylamine into ammonium salt dissolved in the aqueous phase, separating the oil and water and collecting the aqueous phase;

[0015] S2, adding lye to the obtained aqueous phase to convert the ammonium salt back to triethylamine;

[0016] S3, rectifying / stripping the solution obtained in step S2 to collect the gas phase at the top of the column and condense to obtain a triethylamine solution;

[0017] S4, cooling the triethylamine solution in step S3 to 20℃ or below and filtering to remove solid impurities;

[0018] S5, adding lye to the filtrate, high-speed mixing to obtain an emulsion, and then centrifuging to separate and collect the oil phase, which is the reused triethylamine solution.

[0019] As some examples of the present application, in step S1, the inorganic acid is one or both of hydrochloric acid and sulfuric acid;

[0020] Preferably, the concentration of the aqueous inorganic acid solution is 0.5-10wt%, and the amount of the aqueous inorganic acid solution is 8-10 times the mass of the PC oil phase reaction liquid.

[0021] Preferably, in step S1, the oil-water separation uses one or more of a coalescence separator, an inclined plate separator, and a centrifugal extraction separator.

[0022] As some examples of the present application, the PC oil phase reaction liquid is an oil phase product obtained by oil-water separation of a polycarbonate reaction liquid prepared by interfacial polycondensation using bisphenol A and phosgene as raw materials in the presence of a catalyst triethylamine;

[0023] Preferably, the content of polycarbonate in the PC oil phase reaction liquid is 10-25wt%, and the content of the catalyst triethylamine is 100-500ppm.

[0024] As some examples of the present application, in step S2, the alkali solution is a sodium hydroxide and / or potassium hydroxide solution;

[0025] Preferably, the amount of the alkali solution added is such that the pH of the aqueous phase is >12;

[0026] Preferably, the concentration of the alkali solution is 20-40wt%.

[0027] As some examples of the present application, in step S3, the rectification / stripping conditions are: column still temperature 100-140°C, theoretical plate number 20-40, and column still steam usage 3-10% of the feed amount.

[0028] As some examples of the present application, in step S4, the triethylamine solution is cooled to 10-15°C, and then filtered;

[0029] Preferably, step S4 is carried out by a filter press filter or a candle filter.

[0030] As some examples of the present application, in step S5, the alkali solution is a sodium hydroxide and / or potassium hydroxide solution;

[0031] Preferably, the amount of the alkali solution added is 3-5% of the mass of the filtrate;

[0032] Preferably, the concentration of the alkali solution is 5-12wt%.

[0033] As some examples of the present application, in step S5, the high-speed mixing uses a homogenizer or a high-speed mixer, and preferably the stirring speed is 1000-3500rpm.

[0034] Preferably, the centrifugal speed in step S5 is 1500-2800 rpm, and the water content in the oil phase after centrifugal separation is 100-300 ppm.

[0035] The present application also provides a recycled triethylamine solution recovered by the method described above, which comprises 2-4 wt% of triethylamine, ≤10 ppm of structural impurities of formula II, and the balance of oil phase solvent.

[0036]

[0037] Preferably, the oil phase solvent is selected from one or more of dichloromethane, chloroform, tetrachloroethane, chlorobenzene, tetrahydrofuran, dioxane, and pyridine.

[0038] The present application also provides a recycled triethylamine solution recovered by the method described above or the recycled triethylamine solution described above for use as a catalyst in the preparation of polycarbonates by interfacial polycondensation.

[0039] Specific application methods are, for example:

[0040] The oil phase solvent dissolving phosgene is subjected to interfacial polycondensation reaction with the water phase dissolving bisphenol A and alkali metal hydroxide in the presence of the recycled triethylamine solution and a capping agent to prepare polycarbonates.

[0041] Preferably, after the reaction is completed, the polycarbonate reaction solution is subjected to oil-water separation to obtain an oil phase product, and the catalyst triethylamine is recycled and utilized according to the recycling method described above.

[0042] Preferably, the amount of phosgene added is 1-1.3 times the molar amount of bisphenol A.

[0043] Preferably, the concentration of bisphenol A in the water phase is 10-25 wt%.

[0044] Preferably, the alkali metal hydroxide is sodium hydroxide / potassium hydroxide; more preferably, the concentration of alkali metal hydroxide in the water phase is 3-10 wt%.

[0045] Preferably, the amount of the recycled triethylamine solution added is 0.2-0.6 wt% based on the mass of triethylamine relative to bisphenol A.

[0046] Preferably, the capping agent is one or more of monohydroxy phenolic compounds, preferably phenol, p-tert-butyl phenol, and p-cumyl phenol.

[0047] Preferably, the amount of the capping agent added is 1-3 wt% of the mass of bisphenol A.

[0048] Preferably, the reaction temperature of the interfacial polycondensation reaction is 20-50°C.

[0049] Preferably, the oil phase solvent is selected from one or more of dichloromethane, chloroform, tetrachloroethane, chlorobenzene, tetrahydrofuran, dioxane, and pyridine.

[0050] Preferably, after the reaction is completed, oil and water are separated by one or more of a static separator and / or a dynamic separator, preferably an inclined plate separator, a coalescing separator, or a centrifugal extraction separator, to obtain a polycarbonate oil phase reaction solution.

[0051] The recycling method of the present invention can obtain a recycled triethylamine solution with extremely low impurity content as shown in Formula II. Reusing it in the polycarbonate preparation process can effectively improve the heat resistance, powder color and transmittance of polycarbonate. Detailed Implementation

[0052] The present invention will be further illustrated below with specific embodiments. These embodiments are merely illustrative and do not limit the scope of the invention.

[0053] The main raw material information used in the following embodiments of the present invention is as follows:

[0054] Bisphenol A: Industrial grade, Wanhua Chemical;

[0055] Phosgene: Industrial grade, Wanhua Chemical;

[0056] Triethylamine: analytical grade, purchased from Tianjin Kemeo Technology Co., Ltd.;

[0057] p-tert-Butylphenol: analytical grade, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0058] Dichloromethane: analytical grade, purchased from Beijing Innocare Chemical Reagent Co., Ltd.;

[0059] Pure water: Industrial grade, Wanhua Chemical;

[0060] Sodium hydroxide: analytical grade, purchased from Tianjin Kemeo Chemical Reagent Co., Ltd.

[0061] Hydrochloric acid: 31%, Wanhua Chemical

[0062] Sulfuric acid: 98%, purchased from Beijing Inokai Chemical Reagent Co., Ltd.

[0063] The main equipment information used in the following embodiments of the present invention is as follows:

[0064] Inclined plate separator: purchased from Sulzer

[0065] Stripping tower: purchased from Sulzer

[0066] Water-oil separator / coalescer: purchased from Frankenstein Company

[0067] High-speed mixer: purchased from Laining

[0068] homogenizer: purchased from lening

[0069] centrifuge: purchased from chongqing jiangbei

[0070] filter: purchased from shangyang filter.

[0071] The performance test methods involved in the following examples of the present application are as follows:

[0072] Substance content determination: determined using a GC-2030 gas chromatograph, an HS-10 equipped with a hydrogen flame ionization detector (FID) and a headspace autosampler (Shimadzu Corporation), and a chromatographic column (DB-624 column, 30 m x 0.53 mm x 3.0 μm, Agilent Technologies).

[0073] Powder a, b, L value: detected using a color difference meter

[0074] PC test piece YI value: detected using a color difference meter

[0075] Crystal point test: tested according to the method specified in ASTM D3351, the film processing of polycarbonate was performed using a TTC-1200 model casting machine from Richard E. Mistler Company, and the testing instrument was a CPJ-3030A high projection instrument from Suzhou Shifeng Precision Instrument Company

[0076] 380 nm transmittance: LS182 optical transmittance measuring instrument.

[0077] Preparation example

[0078] A water phase solution with a bisphenol A concentration of 12 wt% and a sodium hydroxide concentration of 5 wt% was prepared, and was fed into the reaction kettle at a flow rate of 15 t / h, while phosgene was fed into the reaction kettle at a flow rate of 0.9 t / h, dichloromethane was fed into the reaction kettle at a flow rate of 12 t / h, 3% triethylamine in dichloromethane was fed into the reaction kettle at a flow rate of 120 kg / h, and p-tert-butylphenol was fed into the reaction kettle at a flow rate of 27 kg / h, and the interfacial polymerization reaction was carried out at 25°C. After the reaction was completed, oil-water separation was performed by a inclined plate separator, the water phase was treated as waste water, and the oil phase composition was: polycarbonate 15%, triethylamine 200 ppm, dichloromethane 85%, which was used as the PC oil phase reaction liquid raw material for each example and comparative example.

[0079] Example 1

[0080] A method for recovering a catalyst triethylamine in a polycarbonate production process, comprising the following steps:

[0081] S1, 1% hydrochloric acid solution was added to the PC oil phase reaction solution, the amount of the latter was 10 times the mass of the former, and stirring was carried out at a speed of 70 r / min for 10 min. After acid washing, oil-water separation was carried out using a coalescence separator, and the aqueous phase was collected. After the oil phase was desolvated, the PC powder was obtained by drying;

[0082] S2, 22% sodium hydroxide solution was added to the obtained aqueous phase until pH = 12.8;

[0083] S3, the solution obtained in step S2 was passed into a stripping tower, the temperature of the tower bottom was controlled at 110°C, the theoretical plate number of the stripping tower was 23, and the amount of steam used in the tower bottom was 5% of the feed amount. The gas phase obtained by stripping was condensed and collected to obtain a triethylamine solution;

[0084] S4, the triethylamine solution in step S3 was cooled to 10°C, and a filter press filter was used to remove solid impurities;

[0085] S5, 6% sodium hydroxide solution was added to the filtrate, the amount of which was 5% of the mass of the filtrate, and the mixture was fully stirred (speed 1500 rpm) in a high-speed mixer to obtain an emulsion. The emulsion was then centrifuged at 1750 rpm, and the oil phase collected was the reused triethylamine solution, which contained 283.8 ppm of water.

[0086] The reused triethylamine solution provided by the embodiment includes 3.1 wt% of triethylamine, 8.4 ppm of impurities of formula II, and 96.9 wt% of dichloromethane;

[0087] The formula II substance is enriched by the following method and is qualitatively analyzed by nuclear magnetic hydrogen spectrum:

[0088] 10 kg of the oil phase (i.e., the reused triethylamine solution) obtained by centrifugation was placed in a 20 L jacketed stirring kettle, the jacket temperature was set to 90°C for evaporation and concentration, and pure dichloromethane was added to dissolve the residual heavy components. The solution was analyzed to determine the nuclear magnetic structure.

[0089] 1H NMR (CDCl3, 500 MHz): δ 7.36-7.58 (m, 2H), 6.32-6.59 (m, 2H), 6.53-6.69 (m, 2H), 6.12-6.33 (m, 2H), 5.78-6.01 (m, 2H), 4.89-5.29 (m, 1H), 4.02 (q, J = 7.12 Hz, 2H), 3.78 (q, J = 7.35 Hz, 2H), 1.99 (t, J = 6.79 Hz, 3H), 1.78 (t, J = 6.91 Hz, 3H)

[0090]

[0091]

Example 2

[0092] A method for recovering triethylamine catalyst in a polycarbonate production process, comprising the following steps:

[0093] S1, add 5% hydrochloric acid solution to the PC oil phase reaction liquid, the amount of the latter is 8 times the mass of the former, stir at a speed of 70 r / min for 10 min, after acid washing, use a coalescing separator for oil-water separation, collect the aqueous phase; after the oil phase is desolvated, dry to obtain PC powder;

[0094] S2, add 30% sodium hydroxide solution to the obtained aqueous phase until pH=13;

[0095] S3, pass the solution obtained in step S2 into a stripping tower, control the temperature of the tower kettle to be 120℃, the theoretical plate number of the stripping tower is 32, the amount of steam used in the tower kettle is 7% of the feed amount, condense and collect the gas phase obtained by stripping to obtain a triethylamine solution;

[0096] S4, cool the triethylamine solution in step S3 to 12℃, and filter out solid impurities using a candle filter;

[0097] S5, add 8% potassium hydroxide solution to the filtrate, the amount is 3.5% of the mass of the filtrate, fully stir (speed 2500 rpm) and mix in a high-speed mixer to obtain an emulsion, then centrifuge at 2200 rpm, and collect the oil phase to obtain a reused triethylamine solution, which contains 174.6 ppm of water.

[0098] The reused triethylamine solution provided by the embodiment contains 3.6 wt% of triethylamine, 6.7 ppm of impurities of formula II, and 96.4 wt% of dichloromethane.

[0099]

Example 3

[0100] A method for recovering triethylamine catalyst in a polycarbonate production process, comprising the following steps:

[0101] S1, add 10% hydrochloric acid solution to the PC oil phase reaction liquid, the amount of the latter is 9 times the mass of the former, stir at a speed of 70 r / min for 10 min, after acid washing, use a coalescing separator for oil-water separation, collect the aqueous phase; after the oil phase is desolvated, dry to obtain PC powder;

[0102] S2, add 40% potassium hydroxide solution to the obtained aqueous phase until pH=13.5;

[0103] S3, pass the solution obtained in step S2 into a stripping tower, control the temperature of the tower kettle to be 135℃, the theoretical plate number of the stripping tower is 37, the amount of steam used in the tower kettle is 10% of the feed amount, condense and collect the gas phase obtained by stripping to obtain a triethylamine solution;

[0104] S4, the triethylamine solution in step S3 is cooled to 15℃, and solid impurities are removed by filtering with a candle filter;

[0105] S5, 12% potassium hydroxide solution is added to the filtrate, the amount of addition is 3% of the mass of the filtrate, and the mixture is fully stirred (speed is 3250 rpm) in a high-speed mixer to obtain an emulsion, and then centrifuged at 2750 rpm, and the oil phase is collected as the reused triethylamine solution, wherein the water content is 102.5 ppm.

[0106] The reused triethylamine solution provided by the embodiment includes 2.2 wt% of triethylamine, 2.4 ppm of structural impurities of formula II, and 97.8 wt% of dichloromethane.

[0107] Comparative Example 1

[0108] The PC oil phase reaction solution provided by the preparation example of the application is used as a raw material, and the triethylamine catalyst is recovered by referring to the method in Example 1 of patent CN117801254A. Analysis shows that the reused triethylamine solution includes 2.8 wt% of triethylamine, 322.4 ppm of structural impurities of formula II, and 97.2 wt% of dichloromethane.

[0109] Comparative Example 2

[0110] The triethylamine solution prepared in steps S1-S3 of Example 1 is directly used as a reused triethylamine solution, wherein the triethylamine is 2.9 wt%, the structural impurities of formula II are 637 ppm, and the dichloromethane is 97.1 wt%.

[0111] Application Example

[0112] The reused triethylamine solutions prepared in each of the examples and comparative examples are adjusted to have a mass concentration of 3% of triethylamine (evaporated or supplemented with solvent), and are reused in the preparation of PC according to the following methods, respectively.

[0113] A water phase solution with a concentration of 12 wt% of bisphenol A and 5 wt% of sodium hydroxide is prepared, and is fed into a reaction kettle at a flow rate of 15 t / h, while phosgene is fed into the reaction kettle at a flow rate of 0.9 t / h, dichloromethane is fed into the reaction kettle at a flow rate of 12 t / h, 3% triethylamine dichloromethane solution is fed into the reaction kettle at a flow rate of 120 kg / h, and p-tert-butyl phenol is fed into the reaction kettle at a flow rate of 27 kg / h, and an interfacial polymerization reaction is carried out at 25℃. After the reaction is completed, oil and water are separated by a inclined plate separator, the water phase is treated as waste water, 10% hydrochloric acid solution is added to the oil phase, the amount of hydrochloric acid added is 10% of the mass of the oil phase, the mixture is stirred at a speed of 70 r / min for 10 min, and then oil and water are separated by a coalescence separator, the oil phase is collected, desolvated, and dried to obtain PC powder.

[0114] The PC powder prepared by using the reused triethylamine solutions in each of the examples and comparative examples as catalysts is subjected to the following performance tests, and the results are shown in Table 1.

[0115] Table 1, PC performance test

[0116]

[0117]

[0118] The above only is the preferred embodiment of the present application, it should be pointed out, for the ordinary skilled in the art, without departing from the method of the present application, can also make several improvements and supplements, these improvements and supplements should also be considered the protection scope of the present application.

Claims

1. A method for recovering triethylamine, a catalyst, during polycarbonate production, characterized in that, Includes the following steps: S1. Add an aqueous solution of inorganic acid to the PC oil phase reaction solution to convert triethylamine into ammonium salt that dissolves in the aqueous phase. Separate the oil and water and collect the aqueous phase. S2. Add alkaline solution to the obtained aqueous phase to convert the ammonium salt back into triethylamine; S3. The solution obtained in step S2 is subjected to distillation or stripping, and the gas phase at the top of the column is collected and condensed to obtain a triethylamine solution; S4. Cool the triethylamine solution from step S3 to 20°C or below and filter to remove solid impurities; S5. Add alkali solution to the filtrate, mix at high speed to obtain emulsion, then centrifuge to separate, and collect the oil phase as the reusable triethylamine solution.

2. The method for recovering triethylamine catalyst in the polycarbonate production process according to claim 1, characterized in that, In step S1, the inorganic acid is one or both of hydrochloric acid and sulfuric acid.

3. The method for recovering triethylamine catalyst in the polycarbonate production process according to claim 2, characterized in that, The concentration of the inorganic acid aqueous solution is 0.5-10 wt%, and the amount of inorganic acid aqueous solution used is 8-10 times the mass of the PC oil phase reaction solution.

4. The method for recovering triethylamine catalyst in the polycarbonate production process according to claim 1, characterized in that, The PC oil phase reaction solution is the oil phase product obtained after oil-water separation of a polycarbonate reaction solution prepared by interfacial polycondensation using bisphenol A and phosgene as raw materials in the presence of the catalyst triethylamine.

5. The method for recovering triethylamine catalyst in the polycarbonate production process according to claim 4, characterized in that, The PC oil phase reaction solution contains 10-25 wt% polycarbonate and 100-500 ppm triethylamine catalyst.

6. The method for recovering triethylamine catalyst in the polycarbonate production process according to any one of claims 1-5, characterized in that, In step S2, the alkaline solution is a sodium hydroxide and / or potassium hydroxide solution.

7. The method for recovering triethylamine catalyst in the polycarbonate production process according to claim 6, characterized in that, The amount of alkali added makes the pH of the aqueous phase >12.

8. The method for recovering triethylamine catalyst in the polycarbonate production process according to claim 6, characterized in that, The concentration of the alkali solution is 20-40 wt%.

9. The method for recovering triethylamine catalyst in the polycarbonate production process according to any one of claims 1-5, characterized in that, In step S3, the distillation or stripping conditions are: bottom temperature 100-140℃, theoretical plate number 20-40, and bottom steam consumption 3-10% of the feed rate.

10. The method for recovering triethylamine catalyst in the polycarbonate production process according to any one of claims 1-5, characterized in that, In step S4, the triethylamine solution is cooled to 10-15°C and then filtered.

11. The method for recovering triethylamine catalyst in the polycarbonate production process according to claim 10, characterized in that, Step S4 involves filtration using a pressure filter or a candle filter.

12. The method for recovering triethylamine catalyst in the polycarbonate production process according to any one of claims 1-5, characterized in that, In step S5, the alkaline solution is a sodium hydroxide and / or potassium hydroxide solution.

13. The method for recovering triethylamine catalyst in the polycarbonate production process according to claim 12, characterized in that, The amount of alkali added is 3-5% of the mass of the filtrate.

14. The method for recovering triethylamine catalyst in the polycarbonate production process according to claim 12, characterized in that, The concentration of the alkali solution is 5-12 wt%.

15. The method for recovering triethylamine catalyst in the polycarbonate production process according to any one of claims 1-5, characterized in that, In step S5, high-speed mixing is performed using a homogenizer or a high-speed mixer.

16. The method for recovering triethylamine catalyst in the polycarbonate production process according to claim 15, characterized in that, In step S5, the high-speed mixing speed is 1000-3500 rpm.

17. The method for recovering triethylamine catalyst in the polycarbonate production process according to claim 15, characterized in that, In step S5, the centrifugation speed is 1500-2800 rpm, and the water content of the oil phase after centrifugation is 100-300 ppm.

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