Bisphenol A anion regeneration system and regeneration method

Abstract

The invention provides a bisphenol A anion regeneration system and method. The bisphenol A anion regeneration system comprises an anion bed, and an inlet pipeline of the anion bed is communicated with a desalted water inlet pipe, a phenol inlet pipe and a caustic soda inlet pipe; the anion bed is provided with a top emptying pipeline and a bottom emptying pipeline, a reverse flow pipeline is arranged to be communicated with the inlet pipeline and the bottom emptying pipeline, and an upper end inlet of the bottom emptying pipeline is higher than the upper surface of the anion bed. The method has the beneficial effects that the service life of an expensive anion catalyst is prolonged, and the huge cost of frequently replacing a new catalyst is avoided through cyclic regeneration. And the phenol solution used in the regeneration process can be recycled, and the waste alkali liquid can be subjected to centralized treatment or partial recovery, so that the material consumption and the waste treatment cost are further reduced. In addition, during regeneration operation, materials are guided into a crystallization system through valve switching, shutdown of the whole production system is avoided, production continuity is guaranteed, and the equipment utilization rate and the overall economic benefit are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical industry, and in particular to a bisphenol A anion regeneration system and a regeneration method. Background Art

[0002] In the industrial production of bisphenol A, phenol and acetone enter the reactor at a specific molar ratio and undergo condensation catalyzed by an acidic catalyst (such as a sulfonic acid ion exchange resin) to produce bisphenol A. The key to this process lies in catalyst stability, but in actual operation, the sulfonic acid groups (—SO₃H) of the resin catalyst are prone to shedding. These detached sulfonic acid groups, when introduced into subsequent systems, not only catalyze side reactions to form colored impurities such as quinones and polyphenols, but also trigger isomerization or degradation of the bisphenol A molecules, darkening the product's color and directly affecting its optical purity and performance.

[0003] To address this issue, the current mainstream process incorporates an anion bed system downstream of the reactor. This system, filled with a weakly basic anion exchange resin, absorbs free sulfonate ions and acidic byproducts through its alkaline groups, thereby neutralizing the acidity of the system and inhibiting the pigment chain reaction, ensuring that the color of the bisphenol A meets the standard.

[0004] However, this solution has a significant bottleneck: the adsorption capacity of weakly alkaline resins is limited. As the operating time increases, their active sites are gradually occupied by sulfonic acid groups, and the adsorption efficiency continues to decline. This deactivation is not only due to physical adsorption saturation, but also involves chemical poisoning and mechanical damage to the resin structure caused by long-term swelling / contraction. Once the anion bed fails, the system acidity will be out of control, forcing the unit to shut down and replace the catalyst. Each replacement takes a lot of time and involves equipment isolation, cleaning, unloading, new catalyst activation and system restart. This not only causes huge production losses, but also requires dealing with the solid waste pollution caused by waste resins. Therefore, there is an urgent need to develop a new system and corresponding process to solve the current production dilemma. Summary of the Invention

[0005] In order to solve the problem that the anion bed fails due to catalyst failure, resulting in system shutdown and replacement, which in turn causes huge production losses and solid waste pollution.

[0006] The present invention provides a bisphenol A anion regeneration system, comprising an anion bed, wherein inlet pipes of the anion bed are respectively connected to a desalted water inlet pipe, a phenol inlet pipe and a caustic soda inlet pipe; the anion bed is provided with a top vent pipe and a bottom vent pipe, and a reverse flow pipe is provided to connect the inlet pipe and the bottom vent pipe, wherein the upper end inlet of the bottom vent pipe is higher than the upper surface of the anion bed.

[0007] As a preferred solution, the inlet pipeline is connected to a nitrogen inlet pipe, and the nitrogen inlet pipe is provided with a nitrogen inlet valve.

[0008] As a preferred solution, a sight glass is provided on the top vent pipe.

[0009] As a preferred solution, the desalted water inlet pipe is provided with a desalted water inlet valve, the phenol inlet pipe is provided with a phenol inlet valve, the caustic soda inlet pipe is provided with a caustic soda inlet valve, the top vent pipe is provided with a top vent valve, and the bottom vent pipe is provided with a bottom vent valve.

[0010] As a preferred solution, the reverse flow pipeline is provided with a reverse cleaning valve, and the reverse cleaning valve is a double-layer valve.

[0011] As a preferred solution, an inlet valve is provided on the inlet pipeline between the nitrogen inlet pipe and the reverse flow pipeline.

[0012] Also provided is a bisphenol A anion regeneration method for the bisphenol A anion regeneration system, comprising the following steps: S1. Close the anion bed feed shut-off valve, open the phenol inlet valve and use phenol solution to replace the anion bed, so that the bisphenol A content in the anion bed is reduced to less than 3%, and then close the phenol inlet valve; after the phenol replacement is completed, open the desalted water inlet valve and use 65-75 ° C desalted water with a conductivity of less than 50 us / cm to replace the anion bed catalyst, so that the conductivity of the desalted water discharged from the bottom vent pipe is less than 50 us / cm, and then close the desalted water inlet valve; S2. Open the caustic soda inlet valve and backwash valve, close the inlet valve and bottom vent valve, and replace the anion bed with a 5% caustic soda solution. Observe that the caustic soda liquid level is 10-20 cm above the catalyst liquid level. Close the caustic soda inlet valve, soak the catalyst for 24 hours, and then open the bottom vent valve to drain the caustic soda solution. After caustic soda regeneration is complete, open the desalted water inlet valve and replace the anion bed catalyst with desalted water at 65-75°C and a conductivity of less than 50 μS / cm. Ensure that the desalted water discharged from the bottom vent pipe has a conductivity of less than 50 μS / cm or a pH between 7 and 9. Close the desalted water inlet valve. S3. Close the bottom vent valve, open the phenol inlet valve and the top vent valve, add phenol solution until phenol solution appears in the sight glass, close the backwash valve and open the inlet valve and the bottom vent valve, use phenol solution to replace the anion bed catalyst, reduce the bisphenol A content in the anion bed to below 3% to complete the replacement, and close the phenol inlet valve.

[0013] As a preferred solution, after closing the anion bed feed shut-off valve, the material inlet pipeline is connected to the crystallization system to avoid system shutdown.

[0014] As a preferred solution, when using desalted water to replace the anion bed catalyst, open the desalted water inlet valve, backwash valve and top vent valve, close the inlet valve and bottom vent valve, add caustic soda solution until desalted water solution appears in the sight glass, close the backwash valve and open the inlet valve and bottom vent valve, and then use the desalted water solution to replace the anion bed catalyst.

[0015] As a preferred solution, before using desalted water to replace the anion bed catalyst, the nitrogen inlet valve is opened to use nitrogen to press the solution in the anion bed out of the anion bed, thereby reducing the amount of desalted water used.

[0016] The beneficial effects of the present invention are: The present invention regenerates the catalyst in the anion bed through the synergistic effect of phenol and caustic soda, enabling multiple recycling. First, the anion bed is displaced with a phenol solution to dissolve and remove residual bisphenol A solids and high-concentration solution on the catalyst surface and in its pores. This reduces the bisphenol A content to below 3%, preventing residual bisphenol A from reacting with the alkali solution in subsequent steps to form viscous bisphenol A sodium salt, thereby clogging the equipment and affecting regeneration.

[0017] The chemical regeneration phase then begins, treating the anion bed with a 5% caustic soda solution. The hydroxide ions in the caustic soda undergo an ion exchange reaction with the bisphenol A anions adsorbed on the catalyst's active sites, desorbing the deactivated sodium salt of bisphenol A and restoring catalyst activity.

[0018] Finally, the regenerated and cleaned catalyst bed is re-purged with phenol solution. This ensures that the system is fully phenol-free, ready for resumption of production. Any remaining trace impurities are further displaced, ultimately reducing the BPA content in the bed to below 3%, completing the regeneration process.

[0019] The present invention significantly extends the service life of expensive anionic catalysts. Through cyclic regeneration, the significant cost of frequently replacing new catalysts is avoided. Furthermore, the phenol solution used in the regeneration process can be recycled, and waste alkali liquor can be centrally processed or partially recovered, further reducing material consumption and waste disposal costs. Furthermore, during the regeneration operation, materials are directed into the crystallization system via valve switching, avoiding shutdown of the entire production system, ensuring production continuity, and improving equipment utilization and overall economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below based on specific embodiments and in conjunction with the accompanying drawings, wherein Figure 1 It is a structural schematic diagram of the present invention; Numbers in the figure: 1. Anion bed; 2. Desalted water inlet valve; 3. Phenol inlet valve; 4. Inlet valve; 5. Bottom vent valve; 6. Backwash valve; 7. Nitrogen inlet valve; 8. Caustic soda inlet valve; 11. Top vent valve; 12. Sight glass; 13. Backflow pipeline. DETAILED DESCRIPTION

[0021] To illustrate the features of the present invention, the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0022] Example 1: Please refer to Figure 1 An embodiment of the present invention provides a bisphenol A anion regeneration system. The inlet main pipe of the core equipment anion bed 1 is connected to three key medium pipelines through a multi-channel diversion device: the desalted water inlet pipe is equipped with a pneumatically regulated desalted water inlet valve 2 for injecting high-purity desalted water with a temperature precisely controlled in the range of 65-75°C and a conductivity lower than 50μS / cm; the phenol inlet pipe is equipped with a phenol corrosion-resistant phenol inlet valve 3 for injecting fresh phenol solution and transporting it without leakage; the caustic soda inlet pipe is equipped with a caustic soda inlet valve 8 for injecting a 5% concentration caustic soda solution.

[0023] The vent pipe at the bottom of the anion bed 1 features an inverted U-shaped inlet extending 30 cm above the upper surface of the anion bed 1, effectively preventing catalyst loss. A bottom vent valve 5 equipped with a pressure sensor at the end monitors back pressure in real time to prevent bed collapse. A key innovation lies in the configuration of a reverse-flow pipe 13, connecting the inlet manifold to the bottom vent pipe in reverse flow. This is also equipped with a double-pass mechanically sealed backwash valve 6, resulting in a leakage rate of less than 0.001% at an operating pressure of 6.0 MPa, completely eliminating the potential for corrosion and leakage from strong alkaline media.

[0024] In addition, this embodiment also incorporates a nitrogen assist unit. A high-pressure nitrogen inlet pipe is connected to the main section of the inlet manifold. This unit is equipped with a nitrogen inlet valve 7 and an integrated 0.5 MPa constant pressure regulator to efficiently squeeze out residual liquid at the end of regeneration. At the critical node between the nitrogen inlet pipe and the reverse flow pipeline 13, a specially designed inlet valve 4 serves as the flow control hub. This valve, in conjunction with the reverse flushing valve 6 and the bottom vent valve 5, forms a three-in-one flow control system, enabling seamless switching between forward and reverse bidirectional cleaning, forward and reverse bidirectional regeneration, and nitrogen pressure liquid operation. This design is remotely controlled via a hydraulic actuator, with a response time of less than 0.5 seconds.

[0025] Through precise flow management, this embodiment achieves a catalyst activity recovery rate of 98.7%, shortening the regeneration cycle from 32 hours in the traditional process to 23 hours. The online monitoring system integrates pH / conductivity dual-probe closed-loop control to ensure that the effluent indicators are stable in the high-quality range of pH = 7.5±0.3 and conductivity 48±3μS / cm. During the regeneration period, the entire equipment maintains continuous operation of the main unit through pipeline switching, increasing the annual effective working hours by approximately 380 hours, and increasing the recovery rate of organic matter in the waste liquid to 92%, significantly reducing the cost of hazardous waste treatment.

[0026] Example 2: This embodiment provides a bisphenol A anion regeneration method for the bisphenol A anion regeneration system of embodiment 1, comprising the following steps: S1. Initial replacement phase: Close the anion bed feed shutoff valve and switch the raw material pipeline to the crystallization system to maintain continuous production. Open phenol inlet valve 3 and continuously inject phenol solution into anion bed 1. Through liquid phase displacement, reduce the bisphenol A concentration in the bed to below 3%. After phenol displacement is completed, initiate the desalted water cleaning procedure: Simultaneously open desalted water inlet valve 2, backwash valve 6, and top vent valve 11, and inject high-temperature desalted water at 65-75°C (with conductivity strictly controlled below 50μS / cm) into the system until a stable liquid level is observed in sight glass 12. Then, close backwash valve 6, open inlet valve 4 and bottom vent valve 5 to form a downstream channel, and continue flushing until the discharge water conductivity falls below the 50μS / cm threshold.

[0027] S2. Alkali regeneration stage: Open the caustic soda inlet valve 8 and the backwash valve 6, and close the inlet valve 4 and the bottom vent valve 5. Inject a 5% caustic soda solution into the system, and accurately monitor the liquid level rise process through the sight glass 12 to ensure that the alkali solution covers 10-20 cm above the catalyst bed. Close the caustic soda inlet valve 8 and conduct a 24-hour static soak to allow the hydroxide ions to fully restore the catalyst activity. After the soaking is completed, open the bottom vent valve 5 to discharge the waste alkali solution, and then start the nitrogen inlet valve 7. Use 0.3-0.5MPa nitrogen to press out the residual liquid in the bed, significantly reducing the subsequent water consumption for cleaning. Finally, perform a secondary cleaning of the desalted water according to the operating specifications of Phase 1 until the discharged water meets the qualified standards of conductivity <50μS / cm or pH value 7-9.

[0028] S3. Final activation stage: Close bottom vent valve 5, open phenol inlet valve 3 and top vent valve 11. After the phenol solution is injected until a clear level appears in sight glass 12, close backwash valve 6 and simultaneously open inlet valve 4 and bottom vent valve 5 to establish a forward flow path. Continue phenol replacement until the bisphenol A content in the bed stabilizes below 3%. Finally, close phenol inlet valve 3 to complete the catalyst regeneration process.

[0029] This example regenerates the catalyst in the anion bed through the synergistic effect of phenol and caustic soda, enabling multiple recycling. First, the anion bed is displaced with a phenol solution to dissolve and remove residual bisphenol A solids and high-concentration solution from the catalyst surface and pores. This reduces the bisphenol A content to below 3%, preventing residual bisphenol A from reacting with the alkali solution in subsequent steps to form viscous bisphenol A sodium salt, which could clog the equipment or affect regeneration.

[0030] The chemical regeneration phase then begins, treating the anion bed with a 5% caustic soda solution. The hydroxide ions in the caustic soda undergo an ion exchange reaction with the bisphenol A anions adsorbed on the catalyst's active sites, desorbing the deactivated sodium salt of bisphenol A and restoring catalyst activity.

[0031] Finally, the regenerated and cleaned catalyst bed is re-purged with phenol solution. This ensures that the system is fully phenol-free, ready for resumption of production. Any remaining trace impurities are further displaced, ultimately reducing the BPA content in the bed to below 3%, completing the regeneration process.

[0032] The present invention significantly extends the service life of expensive anionic catalysts. Through cyclic regeneration, the significant cost of frequently replacing new catalysts is avoided. Furthermore, the phenol solution used in the regeneration process can be recycled, and waste alkali liquor can be centrally processed or partially recovered, further reducing material consumption and waste disposal costs. Furthermore, during the regeneration operation, materials are directed into the crystallization system via valve switching, avoiding shutdown of the entire production system, ensuring production continuity, and improving equipment utilization and overall economic benefits.

[0033] The above embodiments and accompanying drawings are intended only to illustrate the technical solutions of the present invention and are not intended to limit the present invention. The present invention has been described in detail with reference to preferred embodiments. Those skilled in the art should understand that any changes, modifications, additions, or substitutions made by those skilled in the art within the spirit and scope of the present invention do not depart from the spirit of the present invention and are intended to fall within the scope of the claims. Other related technical structures not fully disclosed in the present invention constitute prior art in the art.

Claims

1. A bisphenol A anion regeneration system, comprising an anion bed (1), characterized in that: The inlet pipes of the anion bed (1) are respectively connected to the desalted water inlet pipe, the phenol inlet pipe and the caustic soda inlet pipe; the anion bed (1) is provided with a top vent pipe and a bottom vent pipe, and a reverse flow pipe (13) is provided to connect the inlet pipe and the bottom vent pipe, and the upper end inlet of the bottom vent pipe is higher than the upper surface of the anion bed (1).

2. The bisphenol A anion regeneration system according to claim 1, characterized in that: The inlet pipe is connected to a nitrogen inlet pipe, and the nitrogen inlet pipe is provided with a nitrogen inlet valve (7).

3. The bisphenol A anion regeneration system according to claim 1, characterized in that: The top vent pipe is provided with a sight glass (12).

4. The bisphenol A anion regeneration system according to claim 1, characterized in that: The desalted water inlet pipe is provided with a desalted water inlet valve (2), the phenol inlet pipe is provided with a phenol inlet valve (3), the caustic soda inlet pipe is provided with a caustic soda inlet valve (8), the top vent pipe is provided with a top vent valve (11), and the bottom vent pipe is provided with a bottom vent valve (5).

5. The bisphenol A anion regeneration system according to claim 1, characterized in that: The reverse flow pipeline (13) is provided with a reverse cleaning valve (6), and the reverse cleaning valve (6) is a double-layer valve.

6. The bisphenol A anion regeneration system according to claim 2, characterized in that: The inlet pipe is provided with an inlet valve (4) at a position between the nitrogen inlet pipe and the reverse flow pipe (13).

7. A method for regenerating bisphenol A anions, used in the bisphenol A anion regeneration system, characterized in that: The following steps are involved: S1. Close the anion bed feed shut-off valve, open the phenol inlet valve (3), and use phenol solution to replace the anion bed (1), so that the bisphenol A content in the anion bed (1) is reduced to less than 3%, and then close the phenol inlet valve (3); after the phenol replacement is completed, open the desalted water inlet valve (2), and use 65-75°C desalted water with a conductivity of less than 50 us / cm to replace the anion bed catalyst, so that the conductivity of the desalted water discharged from the bottom vent pipe is less than 50 us / cm, and then close the desalted water inlet valve (2); S2. Open the caustic soda inlet valve (8) and the backwash valve (6), close the inlet valve (4) and the bottom vent valve (5), and use a caustic soda solution with a concentration of 5% to replace the anion bed (1). Observe that the caustic soda liquid level is 10-20 cm above the catalyst liquid level. Close the caustic soda inlet valve (8), soak the catalyst for 24 hours, and then open the bottom vent valve (5) to discharge the caustic soda solution. After the caustic soda regeneration is completed, open the desalted water inlet valve (2) and use 65-75℃ desalted water with a conductivity of less than 50us / cm to replace the anion bed catalyst. Make the desalted water discharged from the bottom vent pipe have a conductivity of less than 50us / cm or a pH between 7-9. Close the desalted water inlet valve (2). S3. Close the bottom vent valve (5), open the phenol inlet valve (3) and the top vent valve (11), add phenol solution until the phenol solution appears at the sight glass (12), close the backwash valve (6) and open the inlet valve (4) and the bottom vent valve (5), use the phenol solution to replace the anion bed catalyst, reduce the bisphenol A content in the anion bed (1) to less than 3% to complete the replacement, and close the phenol inlet valve (3).

8. The method for regenerating bisphenol A anions according to claim 7, wherein: After closing the anion bed feed shut-off valve, connect the material inlet pipe to the crystallization system to avoid system shutdown.

9. The method for regenerating bisphenol A anions according to claim 7, wherein: When using desalted water to replace the anion bed catalyst, open the desalted water inlet valve (2), backwash valve (6) and top vent valve (11), close the inlet valve (4) and bottom vent valve (5), add caustic soda solution until the desalted water solution appears at the sight glass (12), close the backwash valve (6) and open the inlet valve (4) and bottom vent valve (5), and then use the desalted water solution to replace the anion bed catalyst.

10. The method for regenerating bisphenol A anions according to claim 7, wherein: Before using desalted water to replace the anion bed catalyst, the nitrogen inlet valve (7) is opened to use nitrogen to press the solution in the anion bed out of the anion bed (1), thereby reducing the amount of desalted water used.

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