A method for recycling and reusing a sub-pallet bpa

Abstract

This invention discloses a method for recycling and reusing off-grade BPA, comprising the following steps: 1) simultaneously feeding off-grade BPA and alkaline solution into a dissolving tank for mixing and dissolution to obtain a raw material solution; 2) heating the raw material solution and feeding it into a cracking reactor packed with a solid alkaline catalyst, where a cracking reaction yields a cracked liquid containing phenol base / phenol / acetone; 3) feeding the cracked liquid into a distillation column for distillation separation, obtaining acetone as a side stream and a phenol base / phenol solution as the bottom of the column; 4) feeding the phenol base / phenol solution and an inorganic acid together into a static mixer for neutralization reaction to obtain a neutralized reaction liquid; 5) feeding the neutralized reaction liquid into a separator for separation to obtain a phenol oil phase and an aqueous phase containing phenol; 6) feeding the aqueous phase containing phenol into a resin bed for adsorption to remove phenol, and discharging the wastewater after it meets the standards. This method can efficiently decompose off-grade BPA and obtain phenol and acetone in high yield.

Description

Technical Field

[0001] This invention relates to a recycling method, and more particularly to a method for recycling secondary BPA. Background Technology

[0002] Bisphenol A (BPA) is an important chemical raw material used in the phosgene process to manufacture polycarbonate (PC). PC production generates a large amount of wastewater containing unreacted BPA. During wastewater treatment, secondary BPA is produced, which does not meet product standards. Due to its high impurity content and diverse types, secondary BPA cannot be used directly, leading to material waste. Recycling high-impurity secondary BPA to produce qualified BPA products is a critical technical challenge that urgently needs to be addressed in this field.

[0003] Patent DE10065087A1 discloses a method for recovering phenols from phenol-based formulations (such as polyesters). This method involves treating these formulations with ammonia and / or primary or secondary amines at temperatures ranging from -70°C to 200°C to decompose and recover phenols. However, using ammonia as a catalyst requires an anhydrous environment, and any remaining ammonia needs to be evaporated from the system, resulting in energy waste and the generation of additional waste liquid. Summary of the Invention

[0004] The purpose of this invention is to address the problem that the by-product BPA produced during the existing phosgenation process for producing PC has low purity and high impurity content, failing to meet usage standards. This invention provides a method for recycling and reusing by-product BPA, which can solve various problems caused by the low purity of by-product BPA and its limitation to solid waste treatment.

[0005] During the research on by-product BPA, the inventors discovered that by-product BPA mainly contains impurities such as water, chlorinated BPA, sodium chloride, ferric chloride, and PC. The high impurity content is the main reason for the difficulty in recycling and processing by-product BPA. This invention utilizes a specially designed solid alkaline catalyst to achieve efficient cracking of by-product BPA and recovery of phenol and acetone. Furthermore, the process has low energy consumption and low processing difficulty, making it more suitable for industrial application.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A method for recycling and reusing secondary BPA (overall process flow as follows) Figure 1 (As shown), including the following steps:

[0008] 1) The secondary brand BPA and alkaline solution are simultaneously transported to the dissolving tank (19) and mixed and dissolved to obtain the raw material solution;

[0009] 2) After heating the raw material liquid, it is sent to the cracking reactor (13) filled with solid base catalyst. The cracking reaction yields a cracked liquid containing sodium phenolate / phenol / acetone.

[0010] 3) The pyrolysis liquid is fed into a distillation column (14) for distillation separation. Acetone product is obtained from the side stream, and sodium phenolate / phenol solution is obtained from the bottom of the column.

[0011] 4) Sodium phenolate / phenol solution and inorganic acid are introduced together into static mixer (15) for neutralization reaction to obtain neutralized reaction solution;

[0012] 5) The neutralization reaction solution is fed into a separator (16) for separation to obtain a phenol oil phase and an aqueous phase containing phenol;

[0013] 6) The aqueous phase containing phenol is fed into the resin bed (17) to adsorb and remove phenol, and the wastewater is discharged after meeting the standards.

[0014] As a preferred embodiment of the present invention, in step 1), the secondary BPA comprises the following components in the following mass ratios: water 10-20%, BPA 78-88%, chlorinated BPA 0.01-0.1%, PC 0.1-0.3%, and metal chloride 1-2%. The metal chloride is generally sodium chloride, ferric chloride, etc.

[0015] As a preferred embodiment of the present invention, in step 1), the amount of BPA and alkali solution mixed and added is 1:(0.01-0.2) based on the mass ratio of BPA to alkali, preferably 1:(0.04-0.1);

[0016] Preferably, the alkali in the alkaline solution is selected from one or more of sodium hydroxide, potassium hydroxide, and calcium hydroxide;

[0017] Preferably, the mass concentration of the alkaline solution is 1-20%, more preferably 5-10%.

[0018] As a preferred embodiment of the present invention, in step 2), the pyrolysis reaction conditions are: temperature 200-300℃, preferably 230-270℃; pressure 1-5MPa, preferably 4-4.5MPa; residence time 0.5-5h, preferably 1-2h.

[0019] Preferably, in step 2), the space velocity of the feed liquid is 0.5-2 BV / h;

[0020] Preferably, the pyrolysis reactor can be any one of a batch reactor or a tubular reactor. More preferably, the pyrolysis reactor is made of any one or more of the following materials: carbon steel, 316L, nickel, 59 alloy, and Harbin C.

[0021] As a preferred embodiment of the present invention, the metal elements in the solid base catalyst include iron, calcium, manganese and aluminum, and the molar ratio of (iron + calcium) / (manganese + aluminum) is (2-5):1, preferably (3-4):1; when the content of metal elements in the solid base catalyst satisfies the above relationship, phenol and acetone can be recovered in high yield.

[0022] Furthermore, in the solid base catalyst, the molar ratio of iron to calcium is 1:(4-9), and the molar ratio of manganese to aluminum is 1:(3-8). Continued research unexpectedly revealed that the above catalyst composition has a significant impact on improving the phenol yield.

[0023] The solid base catalyst can be prepared by at least one of the following methods: co-precipitation, hydrothermal method, adsorption method, ball milling method, impregnation method, and sol-gel method. The present invention does not impose any restrictions on this method, but from the perspective of ease of operation, the co-precipitation method is preferred.

[0024] The following are feasible examples of preparing solid base catalysts by coprecipitation:

[0025] (1) First, prepare a metal salt solution using demineralized water. The metal salts added are soluble salts of iron, calcium, manganese, and aluminum.

[0026] (2) Prepare sodium hydroxide solution with demineralized water, mix it with metal salt solution and stir at 50-300 r / min for 4-10 h.

[0027] (3) After the reaction, centrifuge, wash, dry and calcine to obtain a solid base catalyst.

[0028] Preferably, in step (2), the amount of sodium hydroxide used is adjusted to adjust the pH of the mixed solution to 8-12;

[0029] Preferably, the calcination conditions in step (3) are: 400-600℃, calcination under nitrogen atmosphere for 2-8 hours.

[0030] As a preferred embodiment of the present invention, in step 3), the conditions for distillation separation are: reboiler pressure 20 kPag-200 kPag, reboiler temperature 105℃-130℃, and reflux ratio of (1-5):1.

[0031] Preferably, the distillation column is selected from either a plate column or a packed column, with a plate column being the preferred choice.

[0032] Preferably, the theoretical number of plates in the plate tower is 10-30, more preferably 20-25;

[0033] Preferably, the plate tower can be made of any one of 304, 316L, or carbon steel, with 316L being the preferred material.

[0034] The acetone product obtained from the side stream after separation by the distillation column has a purity of >99.8%, a water content of <0.2%, and a potassium permanganate decolorization time of >360 min.

[0035] As a preferred embodiment of the present invention, in step 4), the amount of inorganic acid is adjusted to control the pH to 1-7, preferably 2-6;

[0036] Preferably, the inorganic acid is selected from one or more of sulfuric acid and hydrochloric acid.

[0037] As a preferred embodiment of the present invention, the layerer (16) is a layering tank or a coalescer;

[0038] Preferably, the layered internal components of the coalescer are any one of inclined plates, PTFE mesh, and polyphenylene sulfide filter elements.

[0039] As a preferred embodiment of the present invention, in step 5), the phenol oil phase has a phenol purity > 99% and a water content < 1%.

[0040] As a preferred embodiment of the present invention, the resin bed (17) is filled with a macroporous resin selected from at least one of Tulsimer ADS-600, SEPLITE XDA-1, and Amberlite XAD2;

[0041] Preferably, in step 6), the feed flow rate of the aqueous phase containing phenol in the macroporous resin is 1-8 BV / h, more preferably 3-6 BV / h;

[0042] Preferably, in step 6), the aqueous phase containing phenol has a phenol content of <0.1 ppm and a TOC content of <10 mg / L after adsorption treatment.

[0043] This invention proposes for the first time a solution for recovering phenol and acetone after the cracking of secondary BPA. The process and operation are simple, the phenol recovery rate is high, and the product purity is high. It can be reused in the process and equipment for the production of BPA from phenol, which is beneficial to the economic benefits of enterprises. In addition, the treated wastewater has a low TCO content and can be directly discharged without putting pressure on the environment. Attached Figure Description

[0044] Figure 1 This is a flowchart of the overall process of the present invention.

[0045] Among them, 1. Substandard BPA, 2. Alkali solution, 3. Cracking solution, 4. Sodium phenolate / phenol solution, 5. Inorganic acid, 6. Neutralization reaction solution, 7. Aqueous phase containing phenol, 8. Wastewater, 9. Phenolic oil phase, 10. Tail gas, 11. Acetone, 12. Electric heater, 13. Cracking reactor, 14. Distillation column, 15. Static mixer, 16. Separator, 17. Resin bed, 18. Screw conveyor, 19. Dissolving tank. Detailed Implementation

[0046] 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.

[0047] Substandard BPA: It comes from Wanhua Chemical's PC unit and is a substandard BPA granule precipitated from BPA-containing waste brine after acid precipitation. Its composition is: BPA 82.2%, water 16%, sodium chloride 1.5%, PC 0.2%, and chlorinated BPA 0.1%.

[0048] Unless otherwise specified, all other raw materials and reagents can be purchased commercially.

[0049] The following devices are used in the following embodiments of the present invention:

[0050] Cracking reactor: 25L batch reactor.

[0051] Distillation column: The distillation column has an inner diameter of 10cm, a height of 1.5m, a theoretical plate count of 20, and is made of 316L stainless steel.

[0052] Layerer: A coalescer whose internal component is a PTFE wire mesh.

[0053]

Preparation Example 1

[0054] A metal salt solution was prepared with a molar fraction of 13.3% iron, 53.3% calcium, 8.3% manganese, and 25% aluminum. A sodium hydroxide solution with a mass concentration of 0.5 mol / L was also prepared. The sodium hydroxide solution was added to the metal salt solution to maintain the pH at around 10. The mixture was stirred at 200 r / min for 6 h. The solid was obtained by centrifugation, washed with water, dried, and calcined at 450 °C under a nitrogen atmosphere for 4 h to obtain solid base catalyst #1.

[0055]

Preparation Example 2

[0056] A metal salt solution was prepared with a molar fraction of 7.5% iron, 67.5% calcium, 2.8% manganese, and 22.8% aluminum. A sodium hydroxide solution with a mass concentration of 0.5 mol / L was also prepared. The sodium hydroxide solution was added to the metal salt solution to maintain the pH at around 12. The mixture was stirred at 300 r / min for 4 h. The solid was obtained by centrifugation, washed with water, dried, and calcined at 400 °C under a nitrogen atmosphere for 6 h to obtain solid base catalyst #2.

[0057]

Preparation Example 3

[0058] A metal salt solution was prepared with a molar fraction of 11.4% iron, 68.6% calcium, 3.3% manganese, and 16.7% aluminum. A sodium hydroxide solution with a mass concentration of 0.5 mol / L was also prepared. The sodium hydroxide solution was added to the metal salt solution to maintain the pH at approximately 11. The mixture was stirred at 100 rpm for 8 hours. The solid was obtained by centrifugation, washed with water, dried, and calcined at 600℃ under a nitrogen atmosphere for 3 hours to obtain solid alkaline catalyst #3.

[0059]

Preparation Example 4

[0060] A metal salt solution was prepared with a molar fraction of 10.4% iron, 72.9% calcium, 2.1% manganese, and 14.6% aluminum. A sodium hydroxide solution with a mass concentration of 0.5 mol / L was also prepared. The sodium hydroxide solution was added to the metal salt solution to maintain the pH at approximately 9. The mixture was stirred at 250 rpm for 5 hours. The solid was obtained by centrifugation, washed with water, dried, and calcined at 450°C under a nitrogen atmosphere for 5 hours to obtain solid alkaline catalyst #4.

[0061]

Comparative Preparation Example 1

[0062] Solid base catalyst 5# was prepared under essentially the same conditions as preparation 1, except that the metal salt solution was prepared with a molar fraction of 10% iron, 40% calcium, 12.5% ​​manganese, and 37.5% aluminum.

[0063]

Comparative Preparation Example 2

[0064] Solid base catalyst 6# was prepared under essentially the same conditions as preparation 1, except that the metal salt solution was prepared with a molar fraction of 17.3% iron, 69.3% calcium, 3.4% manganese, and 10% aluminum.

[0065]

Comparative Preparation Example 3

[0066] Solid base catalyst 7# was prepared under essentially the same conditions as preparation 1, except that the metal salt solution was prepared with a molar fraction of 37.5% iron, 37.5% calcium, 8.3% manganese, and 16.7% aluminum.

[0067]

Example 1

[0068] A method for recycling and reusing secondary BPA, the process flow is as follows: Figure 1 As shown, it includes the following steps:

[0069] 1) The secondary brand BPA and 7.0% sodium hydroxide solution are fed into the dissolving tank (19) by a screw conveyor (18) at a feed rate of 5 kg / h and 2.35 kg / h respectively, and mixed and dissolved to obtain the raw material liquid;

[0070] 2) The raw material liquid is heated to 230°C by an electric heater and then fed into a cracking reactor (13) filled with solid base catalyst 1#. The reaction pressure is controlled at 4.0 MPa, the residence time is 2 h, and the raw material space velocity is 2 BV / h. The cracking reaction yields a cracked liquid containing sodium phenolate / phenol / acetone.

[0071] 3) The pyrolysis liquid is fed into a distillation column (14) and distilled under the conditions of a pressure of 20 kPag, a temperature of 105 °C and a reflux ratio of 1:1. The side stream yields acetone (99.85% acetone, 0.15% water, potassium permanganate decolorization time 360 ​​min), and the bottom of the column yields sodium phenolate / phenol solution.

[0072] 4) Sodium phenolate / phenol solution and 98% sulfuric acid are introduced into a static mixer (15) for neutralization reaction. The pH is adjusted to 6 to obtain the neutralized reaction solution.

[0073] 5) The neutralization reaction solution is fed into a separator (16) for separation to obtain a phenol oil phase and an aqueous phase containing phenol;

[0074] 6) The aqueous phase containing phenol was fed into a resin bed (17) packed with SEPLITEXDA-1 at a flow rate of 6 BV / h to adsorb and remove phenol. The TOC in the treated wastewater was 6 mg / m³. 3 The phenol concentration was 0.02 ppm, meeting the emission standards.

[0075] In this embodiment, the phenol recovered in step 5) has a purity of 99.2% and a product yield of 98%.

[0076]

Example 2

[0077] A method for recycling and reusing secondary BPA, the process flow is as follows: Figure 1 As shown, it includes the following steps:

[0078] 1) The secondary brand BPA and 10.0% sodium hydroxide solution are fed into the dissolving tank (19) by a screw conveyor (18) at a feed rate of 5 kg / h and 4.38 kg / h respectively, and mixed and dissolved to obtain the raw material liquid;

[0079] 2) The raw material liquid is heated to 270°C by an electric heater and then fed into a cracking reactor (13) filled with solid alkali catalyst 2#. The reaction pressure is controlled at 4.5MPa, the residence time is 1.5h, and the raw material space velocity is 1BV / h. The cracking reaction yields a cracked liquid containing sodium phenolate / phenol / acetone.

[0080] 3) The pyrolysis liquid was fed into a distillation column (14) and distilled under the conditions of a pressure of 200 kPag, a temperature of 135℃ and a reflux ratio of 5:1. The side stream yielded acetone (acetone 99.9%, water 0.1%, potassium permanganate decolorization time 360 ​​min), and the bottom of the column yielded sodium phenolate / phenol solution.

[0081] 4) Sodium phenolate / phenol solution and 35% hydrochloric acid are introduced into a static mixer (15) for neutralization reaction. The pH is adjusted to 2 to obtain the neutralized reaction solution.

[0082] 5) The neutralization reaction solution is fed into a separator (16) for separation to obtain a phenol oil phase and an aqueous phase containing phenol;

[0083] 6) The aqueous phase containing phenol was fed into a resin bed (17) packed with Tulsimer ADS-600 at a flow rate of 3 BV / h to adsorb and remove phenol. The TOC in the treated wastewater was 5 mg / m³. 3 The phenol concentration was 0.02 ppm, meeting the emission standards.

[0084] In this embodiment, the phenol recovered in step 5) has a purity of 99.3% and a product yield of 97%.

[0085]

Example 3

[0086] A method for recycling and reusing secondary BPA, the process flow is as follows: Figure 1 As shown, it includes the following steps:

[0087] 1) The secondary brand BPA and 5.0% sodium hydroxide solution are fed into the dissolving tank (19) by a screw conveyor (18) at a feed rate of 5 kg / h and 3.94 kg / h respectively, and mixed and dissolved to obtain the raw material liquid;

[0088] 2) The raw material liquid is heated to 250°C by an electric heater and then fed into a cracking reactor (13) filled with solid alkali catalyst 3#. The reaction pressure is controlled at 4.2MPa, the residence time is 1h, and the raw material space velocity is 0.5BV / h. The cracking reaction yields a cracked liquid containing sodium phenolate / phenol / acetone.

[0089] 3) The pyrolysis liquid was fed into a distillation column (14) and distilled under the conditions of a pressure of 100 kPag, a temperature of 125 °C and a reflux ratio of 2:1. The side stream yielded acetone (acetone 99.88%, water 0.12%, potassium permanganate decolorization time 360 ​​min) and the bottom of the column yielded sodium phenolate / phenol solution.

[0090] 4) Sodium phenolate / phenol solution and 35% hydrochloric acid are introduced into a static mixer (15) for neutralization reaction. The pH is adjusted to 4 to obtain the neutralized reaction solution.

[0091] 5) The neutralization reaction solution is fed into a separator (16) for separation to obtain a phenol oil phase and an aqueous phase containing phenol;

[0092] 6) The aqueous phase containing phenol was fed into a resin bed (17) packed with AmberliteXAD2 at a flow rate of 4 BV / h to adsorb and remove phenol. The TOC in the treated wastewater was 8 mg / m³. 3 The phenol concentration was 0.04 ppm, meeting the emission standards.

[0093] In this embodiment, the purity of the phenol recovered in step 5) is 99.2%, and the product yield is 98.5%.

[0094]

Example 4

[0095] A method for recycling and reusing secondary BPA, the process flow is as follows: Figure 1 As shown, it includes the following steps:

[0096] 1) The secondary brand BPA and 8.0% sodium hydroxide solution are fed into the dissolving tank (19) by a screw conveyor (18) at a feed rate of 5 kg / h and 2.06 kg / h respectively, and mixed and dissolved to obtain the raw material liquid;

[0097] 2) The raw material liquid is heated to 240°C by an electric heater and then fed into a cracking reactor (13) filled with solid alkali catalyst 4#. The reaction pressure is controlled at 4.1 MPa, the residence time is 2 h, and the raw material space velocity is 1 BV / h. The cracking reaction yields a cracked liquid containing sodium phenolate / phenol / acetone.

[0098] 3) The pyrolysis liquid was fed into a distillation column (14) and distilled under the conditions of a pressure of 4 kPag, a temperature of 115℃ and a reflux ratio of 1:1. The side stream yielded acetone (acetone 99.86%, water 0.14%, potassium permanganate decolorization time 360 ​​min) and the bottom of the column yielded sodium phenolate / phenol solution.

[0099] 4) Sodium phenolate / phenol solution and 98% sulfuric acid are introduced into a static mixer (15) for neutralization reaction. The pH is adjusted to 5 to obtain the neutralized reaction solution.

[0100] 5) The neutralization reaction solution is fed into a separator (16) for separation to obtain a phenol oil phase and an aqueous phase containing phenol;

[0101] 6) The aqueous phase containing phenol was fed into a resin bed (17) packed with AmberliteXAD2 at a flow rate of 5 BV / h to adsorb and remove phenol. The TOC in the treated wastewater was 7 mg / m³. 3 The phenol concentration was 0.04 ppm, meeting the emission standards.

[0102] In this embodiment, the purity of the phenol recovered in step 5) is 99.1%, and the product yield is 97.5%.

[0103] Comparative Example 1

[0104] The secondary BPA was processed in basically the same way as in Example 1, except that the catalyst packed in the cracking reactor (13) was replaced with solid base catalyst 5#.

[0105] In this comparative example, the phenol recovered in step 5) has a purity of 99% and a product yield of 78%.

[0106] Comparative Example 2

[0107] The secondary BPA was processed in essentially the same way as in Example 1, except that the catalyst packed in the cracking reactor (13) was replaced with solid base catalyst 6#.

[0108] In this comparative example, the purity of the phenol recovered in step 5) was 98.9%, and the product yield was 76%.

[0109] Comparative Example 3

[0110] The secondary BPA was processed in essentially the same way as in Example 1, except that the catalyst packed in the cracking reactor (13) was replaced with solid base catalyst 7#.

[0111] In this comparative example, the purity of the phenol recovered in step 5) was 98.5%, and the product yield was 70%.

[0112] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements and additions without departing from the method of the present invention, and these improvements and additions should also be considered within the scope of protection of the present invention.

Claims

1. A method for recycling and reusing secondary BPA, characterized in that, Includes the following steps: 1) The secondary brand BPA and alkaline solution are simultaneously transported to the dissolving tank (19) and mixed and dissolved to obtain the raw material solution; 2) After heating the feed liquid, it is fed into a cracking reactor (13) filled with a solid base catalyst. The cracking reaction yields a cracked liquid containing sodium phenolate / phenol / acetone. The cracking reaction conditions are: temperature 200-300℃, pressure 1-5MPa, residence time 0.5-5h; and the space velocity of the feed liquid is 0.5-2BV / h. The metal elements in the solid base catalyst include iron, calcium, manganese, and aluminum, and the molar ratio of (iron + calcium) / (manganese + aluminum) is (2-5):1; in the solid base catalyst, the molar ratio of iron to calcium is 1:(4-9), and the molar ratio of manganese to aluminum is 1:(3-8). 3) The pyrolysis liquid is fed into a distillation column (14) for distillation separation. Acetone product is obtained from the side stream, and sodium phenolate / phenol solution is obtained from the bottom of the column. 4) Sodium phenolate / phenol solution and inorganic acid are introduced into static mixer (15) for neutralization reaction to obtain neutralized reaction solution; 5) The neutralization reaction solution is fed into a separator (16) for separation to obtain a phenol oil phase and an aqueous phase containing phenol; 6) The aqueous phase containing phenol is fed into the resin bed (17) for adsorption and removal of phenol, and the wastewater is discharged after meeting the standards; the resin bed (17) is filled with macroporous resin, selected from at least one of Tulsimer ADS-600, SEPLITE XDA-1, and Amberlite XAD2.

2. The method for recycling and reusing secondary BPA according to claim 1, characterized in that, In step 1), the secondary BPA comprises the following components in the following mass ratios: water 10-20%, BPA 78-88%, chlorinated BPA 0.01-0.1%, PC 0.1-0.3%, and metal chloride 1-2%.

3. The method for recycling and reusing secondary BPA according to claim 2, characterized in that, In step 1), the amount of BPA and alkali solution added together is 1:(0.01-0.2) based on the mass ratio of BPA to alkali.

4. The method for recycling and reusing secondary BPA according to claim 3, characterized in that, In step 1), the amount of BPA and alkali solution added together is 1:(0.04-0.1) based on the mass ratio of BPA to alkali.

5. The method for recycling and reusing secondary BPA according to claim 3, characterized in that, The alkali in the alkaline solution is selected from one or more of sodium hydroxide, potassium hydroxide, and calcium hydroxide.

6. The method for recycling and reusing secondary BPA according to claim 3, characterized in that, The mass concentration of the alkaline solution is 1-20%.

7. The method for recycling and reusing secondary BPA according to claim 6, characterized in that, The mass concentration of the alkaline solution is 5-10%.

8. The method for recycling and reusing secondary BPA according to any one of claims 1-7, characterized in that, In step 2), the pyrolysis reaction conditions are: temperature 230-270℃, pressure 4-4.5 MPa, and residence time 1-2 h.

9. The method for recycling and reusing secondary BPA according to claim 8, characterized in that, The pyrolysis reactor can be selected from either a batch reactor or a tubular reactor.

10. The method for recycling and reusing secondary BPA according to any one of claims 1-7, characterized in that, In the solid base catalyst, the molar ratio of (iron + calcium) to (manganese + aluminum) is (3-4):

1.

11. The method for recycling and reusing secondary BPA according to any one of claims 1-7, characterized in that, In step 3), the conditions for distillation separation are: reboiler pressure 20 kPag-200 kPag, reboiler temperature 105℃-130℃, and reflux ratio of (1-5):

1.

12. The method for recycling and reusing secondary BPA according to claim 11, characterized in that, The distillation column is selected from either a plate column or a packed column.

13. The method for recycling and reusing secondary BPA according to any one of claims 1-7, characterized in that, In step 4), adjust the amount of inorganic acid to control the pH at 1-7.

14. The method for recycling and reusing secondary BPA according to claim 13, characterized in that, In step 4), adjust the amount of inorganic acid to control the pH at 2-6.

15. The method for recycling and reusing secondary BPA according to claim 14, characterized in that, The inorganic acid is selected from one or more of sulfuric acid and hydrochloric acid.

16. The method for recycling and reusing secondary BPA according to any one of claims 1-7, characterized in that, The layerer (16) is a layering tank or a coalescer.

17. The method for recycling and reusing secondary BPA according to claim 16, characterized in that, The layered internal components of the coalescer are any one of inclined plates, PTFE wire mesh, or polyphenylene sulfide filter elements.

18. The method for recycling and reusing secondary BPA according to any one of claims 1-7, characterized in that, Step 5) In the phenol oil phase, the phenol purity is >99% and the water content is <1%.

19. The method for recycling and reusing secondary BPA according to any one of claims 1-7, characterized in that, In step 6), the feed flow rate of the aqueous phase containing phenol in the macroporous resin is 1-8 BV / h.

20. The method for recycling and reusing secondary BPA according to claim 19, characterized in that, In step 6), the feed flow rate of the aqueous phase containing phenol in the macroporous resin is 3-6 BV / h.

21. The method for recycling and reusing secondary BPA according to claim 19, characterized in that, After adsorption treatment, the aqueous phase containing phenol in step 6) has phenol content of <0.1 ppm and TOC content of <10 mg / L.

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