Sulfonic acid type cation exchange resin as well as preparation method and application thereof

Abstract

The invention discloses sulfonic acid type cation exchange resin and a preparation method and application thereof. The method comprises the following steps: constructing a high-strength resin precursor through two-step polymerization reaction: forming a water phase by using a dispersing agent and a dispersing aid, mixing the water phase with an oil phase containing a polymeric monomer, a cross-linking agent and a first initiator, and carrying out free radical polymerization to form microspheres; and then adding a second initiator, and carrying out heating reaction to enhance the crosslinking density. The composite initiator strategy improves the mechanical stability and crosslinking uniformity of the resin. Subsequently, the resin precursor is subjected to high-temperature short-time sulfonation by concentrated sulfuric acid and a swelling agent to form stable and uniformly distributed sulfonic acid groups, so that the catalytic activity is improved. After the reaction, residues and impurities are effectively removed through gradient pickling and multiple times of water washing, the physical structure of the resin is protected, and high selectivity and long-term stability are ensured. According to the overall scheme, the resin precursor structure, the sulfonation process and the purification step are optimized, and the catalytic performance and the mechanical strength of the resin are remarkably improved.

Description

Technical Field

[0001] This invention belongs to the field of bisphenol A synthesis technology, and relates to a sulfonic acid type cation exchange resin, its preparation method and application. Background Technology

[0002] Bisphenol A (BPA), chemically known as 2,2-bis(4-hydroxyphenyl)propane, is an important organic chemical raw material widely used as a monomer in polymer materials such as polycarbonate and epoxy resin. It is also used in the production of fine chemical products such as plasticizers, flame retardants, antioxidants, heat stabilizers, rubber antioxidants, pesticides, and coatings. Furthermore, it is a key derivative of phenol and acetone.

[0003] Industrially, bisphenol A is mainly synthesized by the condensation of phenol and acetone under acidic catalysis. Theoretically, this reaction has a high yield (90%–95%), but due to numerous side reactions, the actual yield is often less than ideal. The core of the development of synthesis technology lies in the evolution of catalyst systems, which has roughly gone through three stages: the first generation, using sulfuric acid catalysts, was simple but caused severe pollution and produced many byproducts; the second generation, using hydrogen chloride catalysts, offered improved selectivity but was highly corrosive; and the third generation, using ion exchange resin catalysts, has advantages such as environmental friendliness, high selectivity, and long lifespan, and has become the current mainstream technology.

[0004] Like the previous technologies, ion exchange resin catalysis technology requires processes such as condensation, raw material processing, crystal purification and degradation, concentration, and granulation. However, it has significant advantages: this technology uses acidic cations as solid catalysts for heterogeneous catalytic reactions, with the solid resin fixed on the reactor equipment to improve reaction activity, eliminating the need to separate the catalyst and reaction products. Bisphenol A produced using ion exchange resins as catalysts can meet higher quality requirements and has wider applications, producing resin-grade, polycarbonate-grade, and optical-grade products. The non-corrosiveness, high reactivity, high selectivity, and low requirements for equipment materials of resin catalysts have allowed them to rapidly capture a significant share of the global bisphenol A production market. Solid catalysts do not require recovery or recycling and are easy to separate, greatly reducing the amount of waste generated by resin-based processes.

[0005] Although ion exchange resin catalysts have significant advantages over sulfuric acid and hydrochloric acid, several technical bottlenecks still exist in commercial resin catalysts that urgently need to be addressed: 1. The contradiction between pore structure and catalytic performance: Existing macroporous resins typically have a high degree of cross-linking. Catalysts made from these as base resins exhibit high initial catalytic activity and good selectivity, but the catalyst pores are easily blocked, leading to rapid catalyst deactivation and affecting catalyst lifespan. Catalysts made from low-cross-linked gel-type base resins, while exhibiting high catalytic activity and long lifespan, have relatively low selectivity and poor mechanical strength, making them prone to breakage. This contradiction restricts further improvements in catalyst performance. 2. Limitations of thiol modification methods: To improve the catalytic performance of ion exchange resins, it is usually necessary to introduce co-catalytic groups such as thiol groups (-SH). Existing methods for thiol modification mainly include partial reduction (USP3,172,916), partial esterification (USP3,153,001; BP937,072), thiol introduction via sulfonamide covalent bonds (USP4,294,995; USP4,346,247; USP4,396,728), and partial neutralization. However, these methods still have various drawbacks. Although catalysts obtained through partial neutralization exhibit better catalytic performance, existing thiolizing agents such as tetrahydrothiazole or thiazolidinyl ether (USP3,634,341; USP3,760,006), aryl thiolamines or their salts (USP4,045,379), pyridinyl alkyl thiols (USP4,478,956), N-(2-mercaptoalkyl)amides (USP4,595,704; CN85106111), and poly(2-mercaptoalkyl)amides (USP4,595,704; CN85106111) and poly(2-mercaptoalkyl)amides are still subject to various limitations. The effects of compounds such as mercaptoalkylamines (EP268,318; USP4,820,740), alkylmercaptoamines (USP3,394,089; BP1,183,564), N-alkylmercaptoamines (EP144,735), and N,N-dialkylmercaptoamines (CN1,119,129) (JP10,314,595; JP10,211,433; JP10,328573) remain unsatisfactory. 3. Challenges in Mechanical Strength and Stability: Ion exchange resin catalysts face problems of decreased mechanical strength and insufficient stability during long-term use. When the reaction equipment is not in use or is undergoing maintenance, the ion exchange resin should be stored in phenol. If the residence time is too long, acidic groups will detach from the ion exchange resin and dissolve into the phenol, leading to catalyst deactivation.

[0006] Therefore, how to solve a series of problems in the existing technology, such as the poor catalytic activity of strong acid cation exchange resins and the low stability and strength of resins during sulfonation, in order to achieve the efficient synthesis of bisphenol A, has become an important technical problem to be solved by those skilled in the art. Summary of the Invention

[0007] To address the problems existing in the prior art, the present invention provides a sulfonic acid type cation exchange resin, its preparation method and application, thereby solving the technical problems of poor catalytic activity and low resin strength during the sulfonation process of strong acid cation exchange resins.

[0008] This invention is achieved through the following technical solution: A method for preparing a sulfonic acid type cation exchange resin includes the following steps: S1: Dissolve the dispersant and co-dispersant in water until completely dissolved to obtain an aqueous phase; mix the polymerizable monomer, crosslinking agent and first initiator evenly to obtain an oil phase; add the oil phase to the aqueous phase to carry out a free radical polymerization reaction. After the reaction forms microspheres, add the second initiator and continue to heat the reaction to obtain a resin precursor. S2: The resin precursor is mixed and stirred with concentrated sulfuric acid, then a swelling agent is added, and a sulfonation reaction is carried out after heating. After the reaction is completed, the reactants are cooled to room temperature and subjected to gradient acid washing, first water washing, first acid washing, second water washing, second acid washing, and third water washing until neutral to obtain the sulfonic acid type cation exchange resin. The concentration of the acid solution in the first acid washing is greater than that in the second acid washing, and the temperature of the first and third water washings is lower than that of the second water washing.

[0009] Preferably, the first initiator is at least one of tert-butyl peroxide-2-ethylhexanoate and tert-butyl peroxide-3,5,5-trimethylhexanoate.

[0010] Preferably, the second initiator is at least one of cumene hydroperoxide, dicumene hydroperoxide, tert-butyl hydroperoxide, and p-menthol hydroperoxide.

[0011] Preferably, the total mass ratio of the polymeric monomer and crosslinking agent to the mass ratio of the first initiator is 100:(0.2-1.0).

[0012] Preferably, the total mass ratio of the polymeric monomer and crosslinking agent to the second initiator is 100:(0.1-0.5).

[0013] Preferably, the ratio of the resin precursor to concentrated sulfuric acid is 1g:(7-10)mL.

[0014] Preferably, the sulfonation reaction is carried out at a temperature of 125-135°C for 3-5 hours.

[0015] Preferably, in the gradient pickling process, the pickling solution used is sulfuric acid with a mass percentage concentration of 80%, 60%, 40%, 20%, and 5% respectively; the pickling solution used in the first pickling process is sulfuric acid with a mass percentage concentration of 20%-30%; the pickling solution used in the second pickling process is sulfuric acid with a mass percentage concentration of 5%-10%; the resistivity of the water used in the first, second, and third water washing processes is ≥18.0 MΩ·cm; the temperature in the first and third water washing processes is room temperature, and the temperature in the second water washing process is 60~70℃.

[0016] A sulfonic acid type cation exchange resin is prepared by the above method.

[0017] The above-mentioned application of a sulfonic acid-type cation exchange resin in the synthesis of bisphenol A.

[0018] Compared with the prior art, the present invention has the following beneficial technical effects: This invention discloses a method for preparing a sulfonic acid-type cation exchange resin. The method constructs a resin precursor through a two-step polymerization reaction: First, a dispersant and a co-dispersant are dissolved in water to form an aqueous phase, while a polymerizable monomer, a crosslinking agent, and a first initiator are mixed to form an oil phase. These two phases are then subjected to free radical polymerization to form microspheres. Subsequently, a second initiator is added and the temperature is raised to further enhance the crosslinking density, resulting in a high-strength resin precursor. This step employs a composite initiator strategy, effectively improving the mechanical stability and crosslinking uniformity of the resin. Next, the resin precursor undergoes sulfonation treatment by mixing with concentrated sulfuric acid and a swelling agent, followed by a short-time sulfonation reaction at high temperature to form stable sulfonic acid groups. This process not only accelerates the sulfonation rate but also promotes the uniform distribution of sulfonic acid groups, improving catalytic activity. After the reaction, the resin undergoes a meticulous gradient acid washing and multiple water washing processes, including gradient acid washing to remove residues, first and second acid washing for enhanced purification, and a third water washing to neutrality. This effectively protects the physical structure of the resin, reduces impurity content, and ensures the resin's high selectivity and long-term stability. The overall solution significantly improves the catalytic performance and mechanical strength of sulfonic acid-type cation exchange resins by optimizing the resin precursor structure, sulfonation process, and purification steps. Detailed Implementation

[0019] To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used in the specification and claims are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0020] The theories or mechanisms described and disclosed herein, whether right or wrong, should not in any way limit the scope of the invention, that is, the contents of the invention can be implemented without being limited by any particular theory or mechanism.

[0021] In this document, all features defined by numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0022] In this article, unless otherwise specified, “contains,” “includes,” “containing,” “has,” or similar terms cover the meanings of “composed of” and “mainly composed of,” for example, “A contains a” covers the meanings of “A contains a and others” and “A contains only a.”

[0023] For the sake of brevity, not all possible combinations of the technical features in each implementation scheme or embodiment are described herein. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation scheme or embodiment can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification.

[0024] This invention provides a method for preparing a sulfonic acid-type cation exchange resin, comprising the following steps: S1: Preparation of resin precursor: The dispersant and co-dispersant are dissolved in water until completely dissolved to obtain an aqueous phase; the polymeric monomer, crosslinking agent and first initiator are mixed evenly to obtain an oil phase; the oil phase is added to the aqueous phase to carry out a free radical polymerization reaction until the resin skeleton is in a micro-aggregate state to form microspheres; then the second initiator is added and the temperature is raised to continue the reaction to obtain the resin precursor. More specifically, the above process is as follows: the dispersant is dissolved in water until completely dissolved to obtain an aqueous phase; the polymeric monomer, crosslinking agent, and first initiator are mixed evenly to obtain an oil phase; the oil phase is added to the aqueous phase and stirred until the particle size is 0.4-0.8 mm; the temperature is raised to 83-85℃ to carry out a free radical polymerization reaction for 5-8 hours; then the second initiator is added, the temperature is raised to 91-93℃, and the reaction is carried out for 3-6 hours; after the reaction is completed, the polymer is cooled to room temperature, filtered, washed, and dried to obtain the resin precursor. The dispersant is at least one of polyvinyl alcohol, hydroxyethyl cellulose, and sodium carboxymethyl cellulose; in the aqueous phase, the mass ratio of dispersant to water is (0.3-0.8):100; The dispersant is at least one of sodium chloride and sodium dodecylbenzenesulfonate; in the aqueous phase, the mass ratio of the dispersant to water is (0.5-1.5):100; The polymer monomer is at least one of styrene, methylstyrene and ethylstyrene; The crosslinking agent is divinylbenzene, and its content is ≥63%; The first initiator is at least one of tert-butyl peroxide-2-ethylhexanoate and tert-butyl peroxide-3,5,5-trimethylhexanoate; The primary initiators here all belong to the peroxide ester class. Their core commonality is that they have moderate decomposition temperatures and play a major role in the early to mid-stages of the polymerization reaction. The decomposition mechanism of peroxide ester initiators is relatively simple, primarily generating a carboxylic acid radical and a tert-butoxy radical after homolytic cleavage. The latter is the main active species initiating polymerization, and this relatively singular decomposition product makes its kinetic behavior relatively controllable and predictable.

[0025] The second initiator is at least one of the following: cumene hydroperoxide, dicumene hydroperoxide, tert-butyl hydroperoxide, and p-menthol hydroperoxide; The second initiators here all belong to the hydrogen peroxide class, and their core commonality is that they have high decomposition temperatures and play a major role in the middle and later stages of the polymerization reaction. The combined initiation strategy using the first and second initiators constitutes a highly efficient and controllable polymerization initiation system.

[0026] The degree of crosslinking of the resin precursor is 1.5%-4%; Specifically, the total mass ratio of the polymerizable monomers and crosslinking agents to the mass ratio of the first initiator is 100:(0.2-1.0); The total mass ratio of the monomers and crosslinking agent to the second initiator is 100:(0.1-0.5); Here, a first initiator (such as tert-butyl peroxide-2-ethylhexanoate) is used to initiate polymerization at 83-85℃, forming a preliminary loose polymer network framework. Subsequently, a second initiator (such as cumene hydroperoxide) is added to further polymerize at 91-93℃, increasing the crosslinking density and strengthening the network structure. This stepwise initiation process makes the polymerization reaction more uniform and thorough, resulting in a gel-type resin structure with a uniform crosslinked network and an appropriate ratio of working pores in the microporous region. This not only optimizes the diffusion and mass transfer efficiency of reactant molecules but also significantly improves the mechanical strength of the resin, making it more resistant to long-term wear and impact under reaction conditions.

[0027] S2: Precursor sulfonation reaction, specifically including: mixing and stirring the resin precursor with concentrated sulfuric acid, then adding a swelling agent, heating the system, and carrying out the sulfonation reaction. After the reaction is completed, the reactants are cooled to room temperature and subjected to gradient acid washing, one water wash, one acid wash, two water washes, two acid washes, and three water washes until neutral to obtain the sulfonic acid type cation exchange resin.

[0028] More specifically, the above process is as follows: the resin precursor is mixed with concentrated sulfuric acid at a ratio of 1g:(7-10)mL at 20-30℃ and stirred for 10-15 minutes; then the swelling agent is slowly added dropwise to the reaction system, and the mixture is subjected to sulfonation reaction at 125-135℃ for 3-5 hours, during which the swelling agent is recovered; after the reaction is completed, the reactants are cooled to room temperature, and subjected to gradient acid washing, one water washing, one acid washing, two water washing, two acid washing, and three water washing until neutral, to obtain the sulfonic acid type cation exchange resin.

[0029] The concentrated sulfuric acid has a density ≥1.84 g / mL or a content ≥98%.

[0030] The swelling agent is 1,2-dichloroethane or 1,1,2-trichloroethane, with a content ≥99%, and the swelling agent accounts for 30%-50% of the mass of the white spheres, i.e., the resin precursor.

[0031] During this washing process, the resistivity of the water used in the first, second, and third washes is ≥18.0 MΩ·cm.

[0032] In the gradient pickling process, the pickling solution used is sulfuric acid with mass percentage concentrations of 80%, 60%, 40%, 20%, and 5% respectively. The pickling solution used in a single pickling process is sulfuric acid with a mass percentage concentration of 20%-30%; The pickling solution used in the secondary pickling process is sulfuric acid with a mass percentage concentration of 5%-10%; The temperature of the first and third water washes is lower than the temperature of the second water wash; more preferably, the temperature during the first and third water washes is room temperature, and the temperature of the second water wash is 60~70℃.

[0033] Here, gradient pickling is a post-treatment using gradually changing acid concentrations (e.g., from high to low) to avoid excessive expansion or contraction of the resin due to sudden concentration changes, thereby protecting the physical structure of the resin (e.g., pores and crosslinking degree) from damage. At the same time, it gradually removes residual concentrated sulfuric acid, sulfonation byproducts (e.g., sulfonates or sulfates), and unreacted organic matter from the reaction system, ensuring that impurities on the resin surface and inside are effectively removed. Single water wash: Water washing is performed immediately after gradient acid washing, which can quickly dilute and remove most of the acid-soluble impurities, rinse away the residual acid and soluble small molecule impurities in the resin, and prevent these impurities from redepositing or affecting the ion exchange capacity of the resin in subsequent steps. Acid washing: Acid washing is performed after the first water wash to further enhance the purification effect and ensure that the resin is completely converted into the required hydrogen form (H). + Cation exchange resins improve the exchange efficiency and selectivity of the resin; Secondary water wash: Following the first pickling, the secondary water wash can effectively remove residual acid and impurities introduced during the pickling process, and prevent acid accumulation from causing resin degradation. Secondary acid washing: Repeated acid washing steps can ensure the thorough purification of the resin and the uniformity of its ionic form, enhance the chemical stability and service life of the resin, and make it suitable for applications requiring high purity in the synthesis of bisphenol A. Three water washes to neutral: By washing the resin multiple times until the pH of the effluent is neutral, it is ensured that there is no acid residue before use, so that the resin reaches a stable neutral state, ensuring its storage safety and operational reliability, and avoiding interference with subsequent applications (catalytic reactions).

[0034] This invention provides a method for preparing a sulfonic acid-type cation exchange resin. By improving the synthesis process of the resin precursor, the stability and mechanical strength of the resin precursor are significantly enhanced. Secondly, during the sulfonation reaction of the resin precursor, a short-time, high-temperature synthesis method is used for sulfonation, further improving the stability of the sulfonic acid groups and effectively overcoming the problems of instability and easy detachment of sulfonic acid groups in existing technologies. Finally, through meticulous purification and post-treatment, a pure H-type cation exchange resin with moderate acidity and low impurity content is obtained, ensuring its high selectivity and stability. The strong acid cation exchange resin prepared by this invention exhibits excellent stability and mechanical strength, effectively reducing swelling or deformation of the resin during bisphenol A synthesis, ensuring the stability of the reaction effect and the consistency of product quality, adapting to different bisphenol A synthesis process conditions, improving production flexibility and adaptability, and can be used for bisphenol A synthesis.

[0035] This invention improves the synthesis process of resin precursors by using a combination of multiple initiators to prepare resin precursors, which significantly enhances the stability and mechanical strength of resin precursors, effectively solves the problem of low strength of traditional strong acid cation resins, and shortens the resin synthesis time to 1 / 3 of the traditional process.

[0036] In the sulfonation reaction of the resin precursor, the present invention adopts a short-time, high-temperature synthesis method for sulfonation, which further improves the stability of the sulfonic acid group and effectively overcomes the problems of instability and easy shedding of the sulfonic acid group in the prior art, ensuring the stability and reliability of the catalyst in long-term use.

[0037] The strong acid cation exchange resin prepared by this invention exhibits excellent performance stability and mechanical strength, effectively reducing swelling or deformation of the resin during bisphenol A synthesis, ensuring the stability of the reaction effect and the consistency of product quality. The improved process employed in this invention not only enhances the stability and strength of the resin but also reduces corrosion to equipment, effectively extending equipment lifespan, reducing maintenance and replacement costs, and improving the industrial production efficiency of bisphenol A. The catalytic resin prepared by this invention possesses good thermal stability and swelling properties, maintaining stable performance under high temperature and pressure conditions, adapting to different bisphenol A synthesis process conditions, and improving production flexibility and adaptability. A novel macroporous sulfonic acid cation exchange resin, specifically designed as a catalyst for the condensation synthesis of bisphenol A from phenol and acetone, features high catalytic activity, good selectivity, slow deactivation rate, and good mechanical strength.

[0038] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0039] The following examples use instruments and equipment conventional in the art. Experimental methods in the following examples, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. All raw materials used in the following examples are conventional commercially available products with specifications conventional in the art. In this specification and the following examples, unless otherwise specified, "%" refers to weight percentage, "parts" refers to parts by weight, and "ratio" refers to weight proportion.

[0040] Example 1 A method for preparing a sulfonic acid type cation exchange resin includes the following steps: Weigh 3g of polyvinyl alcohol and 20g of sodium dodecylbenzenesulfonate and add them to a 1000mL three-necked flask. Then add 500mL of deionized water, heat to 50℃, and stir until completely dissolved. Add 2mL of 0.1% methylene blue solution and stir evenly to obtain the aqueous phase. The addition of methylene blue here serves two purposes: first, to prevent emulsion polymerization of monomers in water; and second, to eliminate dissolved oxygen in the water through redox reaction, thereby shortening the polymerization induction period.

[0041] Weigh 95.24g of methylstyrene and 4.76g of 63% divinylbenzene and add them to a beaker. Then weigh 0.2g of tert-butyl peroxide-2-ethylhexanoate and add it to the beaker. Mix well to obtain the oil phase. Adjust the stirring height, add the prepared oil phase to the aqueous phase, let stand for 10 minutes, start stirring, adjust the speed to control the particle size at 0.4-0.8 mm, then heat to 85℃ and react for 8 hours. After the reaction, add 0.1 g of hydrogen peroxide to a three-necked flask, heat to 93℃ and react for 6 hours. After the reaction, cool the polymer to room temperature, filter off the mother liquor, wash the precursor with deionized water until clear, and then dry at 100℃ for 5 hours to obtain the resin precursor. Here, adjusting the stirring height is mainly to ensure that the oil and aqueous phases are mixed evenly to form uniformly sized spherical particles, thus ensuring that a uniformly sized resin precursor is formed after the polymerization reaction. Weigh 50g of resin precursor into a dry 1000mL three-necked flask, then add 400mL of concentrated sulfuric acid and stir for 15 minutes. Slowly add 45mL of 1,2-dichloroethane dropwise into the reaction system. After 2 hours, raise the temperature to 133℃ for sulfonation reaction and maintain the temperature for 4 hours. During the reaction, recover 1,2-dichloroethane. After the reaction is complete and cooled to room temperature, sequentially add 80%, 60%, 40%, 20%, and 5% dilute sulfuric acid for gradient acid washing. Reduce the density of the mother liquor to 1.0g / mL through gradient acid washing. The main components of the mother liquor are residual concentrated sulfuric acid and sulfonation byproducts (such as sulfonates or sulfates) in the reaction system. Wash the pellets with cold deionized water until neutral, then add 20% sulfuric acid, heat to 80°C, stir and wash for 2 hours, wash with 70°C deionized water until near neutral, and finally wash with cold deionized water until neutral; then add 10% sulfuric acid, heat to 80°C, stir and wash for 4 hours, and finally wash with cold deionized water until neutral to obtain the final product resin, namely sulfonic acid type cation exchange resin.

[0042] Example 2 A method for preparing a sulfonic acid type cation exchange resin includes the following steps: Weigh 2.5g of polyvinyl alcohol and 17.5g of sodium chloride and add them to a 1000mL three-necked flask. Then add 500mL of deionized water, heat to 50℃, and stir until completely dissolved. Add 2mL of 0.1% methylene blue solution and stir well to obtain the aqueous phase. Weigh 96.03g of methylstyrene and 3.97g of 63% divinylbenzene and add them to a beaker. Then weigh 0.5g of tert-butyl peroxide-3,5,5-trimethylhexanoate and add it to the beaker. Mix well to obtain the oil phase. Adjust the stirring height, add the prepared oil phase to the aqueous phase, let stand for 10 minutes, start stirring, adjust the speed, control the particle size, and when the particle size is qualified (0.4-0.8 mm), raise the temperature to 84℃ and react for 6 hours. After the reaction is complete, add 0.1 g of tert-butyl hydrogen peroxide to a three-necked flask, raise the temperature to 92℃ and react for 5 hours. After the reaction is complete, cool the polymer to room temperature, filter the mother liquor, wash the precursor with deionized water until clear, and then dry at 100℃ for 5 hours to obtain the resin precursor.

[0043] Weigh 50g of resin precursor into a dry 1000mL three-necked flask, then add 430mL of concentrated sulfuric acid and stir for 15 minutes. Slowly add 40mL of 1,2-dichloroethane dropwise into the reaction system, raise the temperature to 130℃ for sulfonation reaction after 2 hours, and maintain the temperature for 4 hours. During the reaction, recover 1,2-dichloroethane. After the reaction is complete, cool to room temperature, and sequentially add dilute sulfuric acid of concentrations of 80%, 60%, 40%, 20%, and 5% for gradient acid washing. Reduce the density of the reaction mother liquor to 1.0g / mL through gradient acid washing. Wash with cold deionized water until neutral, then add 10% sulfuric acid, raise the temperature to 80℃, stir and wash the pellets for 2 hours, wash with 60℃ deionized water until near neutral, and finally wash with cold deionized water until neutral. Add 5% sulfuric acid, raise the temperature to 80℃, stir and wash the pellets for 4 hours, and finally wash with cold deionized water until neutral to obtain the final product resin, namely sulfonic acid type cation exchange resin.

[0044] Example 3 A method for preparing a sulfonic acid type cation exchange resin includes the following steps: Weigh 3g of sodium carboxymethyl cellulose and 10g of sodium chloride and add them to a 1000mL three-necked flask. Then add 500mL of deionized water, heat to 50℃, and stir until completely dissolved. Add 2mL of 0.1% methylene blue solution and stir well to obtain the aqueous phase. Weigh 95.62g of methylstyrene and 4.38g of 80% divinylbenzene and add them to a beaker. Then weigh 1.0g of tert-butyl peroxide-2-ethylhexanoate and add it to the beaker. Mix well to obtain the oil phase. Adjust the stirring height, add the prepared oil phase to the aqueous phase, let stand for 10 minutes, start stirring, adjust the speed, control the particle size, and when the particle size is qualified (0.4-0.8 mm), raise the temperature to 83℃ and react for 5 hours. After the reaction is complete, add 0.5 g of cumene hydroperoxide to a three-necked flask, raise the temperature to 91℃ and react for 3 hours. After the reaction is complete, cool the polymer to room temperature, filter the mother liquor, wash the precursor with deionized water until clear, and then dry at 100℃ for 5 hours to obtain the resin precursor.

[0045] Weigh 50g of resin precursor into a dry 1000mL three-necked flask, then add 380mL of concentrated sulfuric acid and stir for 15 minutes. Slowly add 45mL of 1,2-dichloroethane dropwise into the reaction system, raise the temperature to 130℃ for sulfonation reaction after 2 hours, and maintain the temperature for 5 hours. During the reaction, recover 1,2-dichloroethane. After the reaction is complete, cool to room temperature, and sequentially add dilute sulfuric acid of concentrations of 80%, 60%, 40%, 20%, and 5% for gradient acid washing. Reduce the density of the reaction mother liquor to 1.0g / mL through gradient acid washing. Wash with cold deionized water until neutral, then add 30% sulfuric acid, raise the temperature to 80℃, stir and wash the pellets for 2 hours, wash with 65℃ deionized water until near neutral, and finally wash with cold deionized water until neutral. Add 5% sulfuric acid, raise the temperature to 80℃, stir and wash the pellets for 4 hours, and finally wash with cold deionized water until neutral to obtain the final product resin, namely sulfonic acid type cation exchange resin.

[0046] Example 4 A method for preparing a sulfonic acid type cation exchange resin includes the following steps: Weigh 1.5g of hydroxyethyl cellulose and 25g of sodium chloride and add them to a 1000mL three-necked flask. Then add 500mL of deionized water, heat to 50℃, and stir until completely dissolved. Add 2mL of 0.1% methylene blue solution and stir well to obtain the aqueous phase. Weigh 93.65g of methylstyrene and 6.35g of 63% divinylbenzene and add them to a beaker. Then weigh 0.7g of tert-butyl peroxide-3,5,5-trimethylhexanoate and add it to the beaker. Mix well to obtain the oil phase. Adjust the stirring height, add the prepared oil phase to the aqueous phase, let stand for 10 minutes, start stirring, adjust the speed, control the particle size, and when the particle size is qualified (0.4-0.8 mm), raise the temperature to 83℃ and react for 6 hours. After the reaction is complete, add 0.3 g of dicumyl peroxide to a three-necked flask, raise the temperature to 93℃ and react for 4 hours. After the reaction is complete, cool the polymer to room temperature, filter the mother liquor, wash the precursor with deionized water until clear, and then dry at 100℃ for 5 hours to obtain the resin precursor.

[0047] Weigh 50g of resin precursor and add it to a dry 1000mL three-necked flask. Then add 350mL of concentrated sulfuric acid and stir for 15 minutes. Slowly add 50mL of 1,1,2-trichloroethane dropwise to the reaction system. After 2 hours, raise the temperature to 135℃ for sulfonation reaction and keep it at that temperature for 5 hours. During the reaction, recover 1,1,2-trichloroethane. After the reaction is complete and cooled to room temperature, dilute sulfuric acid of concentrations of 80%, 60%, 40%, 20%, and 5% is added dropwise for gradient acid washing. The density of the reaction mother liquor is reduced to 1.0 g / mL by gradient acid washing. It is then washed with cold deionized water until neutral. Then, 25% sulfuric acid is added, the temperature is raised to 80°C, and the pellets are stirred and washed for 2 hours. It is then washed with 60°C deionized water until near neutral, and finally washed with cold deionized water until neutral. Then, 5% sulfuric acid is added, the temperature is raised to 80°C, and the pellets are stirred and washed for 4 hours. Finally, it is washed with cold deionized water until neutral to obtain the final product resin, namely sulfonic acid type cation exchange resin.

[0048] Example 5 A method for preparing a sulfonic acid type cation exchange resin includes the following steps: Weigh 3.5g of polyvinyl alcohol and 15g of sodium chloride and add them to a 1000mL three-necked flask. Then add 500mL of deionized water, heat to 50℃, and stir until completely dissolved. Add 2mL of 0.1% methylene blue solution and stir well to obtain the aqueous phase. Weigh 96.83g of methylstyrene and 3.17g of 63% divinylbenzene and add them to a beaker. Then weigh 1.0g of tert-butyl peroxide-2-ethylhexanoate and add it to the beaker. Mix well to obtain the oil phase. Adjust the stirring height, add the prepared oil phase to the aqueous phase, let stand for 10 minutes, start stirring, adjust the speed, control the particle size, and when the particle size is qualified (0.4-0.8 mm), raise the temperature to 83℃ and react for 8 hours. After the reaction is complete, add 0.3 g of cumene hydroperoxide to a three-necked flask, raise the temperature to 93℃ and react for 6 hours. After the reaction is complete, cool the polymer to room temperature, filter the mother liquor, wash the precursor with deionized water until clear, and then dry at 100℃ for 5 hours to obtain the resin precursor.

[0049] Weigh 50g of resin precursor into a dry 1000mL three-necked flask, then add 450mL of concentrated sulfuric acid and stir for 15 minutes. Slowly add 40mL of 1,2-dichloroethane dropwise into the reaction system, raise the temperature to 128℃ for sulfonation reaction after 2 hours, and maintain the temperature for 3 hours. During the reaction, recover 1,2-dichloroethane. After the reaction is complete, cool to room temperature, and sequentially add dilute sulfuric acid of concentrations of 80%, 60%, 40%, 20%, and 5% for gradient acid washing. Reduce the density of the reaction mother liquor to 1.0g / mL through gradient acid washing, wash with cold deionized water until neutral, then add 20% sulfuric acid, raise the temperature to 80℃, stir and wash the pellets for 2 hours, wash with 60℃ deionized water until near neutral, and finally wash with cold deionized water until neutral. Then add 7% sulfuric acid, raise the temperature to 80℃, stir and wash the pellets for 4 hours, and finally wash with cold deionized water until neutral to obtain the final product resin, namely sulfonic acid type cation exchange resin.

[0050] Example 6 A method for preparing a sulfonic acid type cation exchange resin includes the following steps: Weigh 4g of polyvinyl alcohol and 10g of sodium chloride and add them to a 1000mL three-necked flask. Then add 500mL of deionized water, heat to 50℃, and stir until completely dissolved. Add 2mL of 0.1% methylene blue solution and stir well to obtain the aqueous phase. Weigh 97.62g of methylstyrene and 2.38g of 63% divinylbenzene and add them to a beaker. Then weigh 0.2g of tert-butyl peroxide-3,5,5-trimethylhexanoate and add it to the beaker. Mix well to obtain the oil phase. Adjust the stirring height, add the prepared oil phase to the aqueous phase, let stand for 10 minutes, start stirring, adjust the speed, control the particle size, and when the particle size is qualified (0.4-0.8 mm), raise the temperature to 85℃ and react for 5 hours. After the reaction is complete, add 0.5 g of dicumyl peroxide to a three-necked flask, raise the temperature to 91℃ and react for 3 hours. After the reaction is complete, cool the polymer to room temperature, filter the mother liquor, wash the precursor with deionized water until clear, and then dry at 100℃ for 5 hours to obtain the resin precursor.

[0051] Weigh 50g of resin precursor into a dry 1000mL three-necked flask, then add 500mL of concentrated sulfuric acid and stir for 15 minutes. Slowly add 30mL of 1,2-dichloroethane dropwise into the reaction system, raise the temperature to 135℃ for sulfonation reaction after 2 hours, and maintain the temperature for 3 hours. During the reaction, recover 1,2-dichloroethane. After the reaction is complete, cool to room temperature, and sequentially add dilute sulfuric acid of concentrations of 80%, 60%, 40%, 20%, and 5% for gradient acid washing. Reduce the density of the reaction mother liquor to 1.0g / mL through gradient acid washing, wash with cold deionized water until neutral, then add 25% sulfuric acid, raise the temperature to 80℃, stir and wash the pellets for 2 hours, wash with 60℃ deionized water until near neutral, and finally wash with cold deionized water until neutral. Add 5% sulfuric acid, raise the temperature to 80℃, stir and wash the pellets for 4 hours, and finally wash with cold deionized water until neutral to obtain the final product resin, namely sulfonic acid type cation exchange resin.

[0052] Comparative Example 1 In this comparative example, only the first initiator was added, specifically: Weigh 2.5g of polyvinyl alcohol and 17.5g of sodium chloride and add them to a 1000mL three-necked flask. Then add 500mL of deionized water, heat to 50℃, and stir until completely dissolved. Add 2mL of 0.1% methylene blue solution and stir well to obtain the aqueous phase. Weigh 96.03g of methylstyrene and 3.97g of 63% divinylbenzene and add them to a beaker. Then weigh 0.6g of tert-butyl peroxide-3,5,5-trimethylhexanoate and add it to the beaker. Mix well to obtain the oil phase. Adjust the stirring height, add the prepared oil phase to the aqueous phase, let stand for 10 minutes, start stirring, adjust the speed, control the particle size, and when the particle size is qualified (0.4-0.8 mm), raise the temperature to 84℃ and react for 6 hours. After the reaction is completed, raise the temperature to 92℃ and react for 5 hours. After the reaction is completed, cool the polymer to room temperature, filter the mother liquor, wash the precursor with deionized water until clear, and then dry at 100℃ for 5 hours to obtain the resin precursor.

[0053] Weigh 50g of resin precursor into a dry 1000mL three-necked flask, then add 430mL of concentrated sulfuric acid and stir for 15 minutes. Slowly add 40mL of 1,2-dichloroethane dropwise into the reaction system, raise the temperature to 130℃ for sulfonation reaction after 2 hours, and maintain the temperature for 4 hours. During the reaction, recover 1,2-dichloroethane. After the reaction is complete, cool to room temperature, and sequentially add dilute sulfuric acid of concentrations of 80%, 60%, 40%, 20%, and 5% for gradient acid washing. Reduce the density of the reaction mother liquor to 1.0g / mL through gradient acid washing. Wash with cold deionized water until neutral, then add 30% sulfuric acid, raise the temperature to 80℃, stir and wash for 2 hours, wash with 60℃ deionized water until near neutral, and finally wash with cold deionized water until neutral. Add 5% sulfuric acid, raise the temperature to 80℃, stir and wash for 4 hours, and finally wash with cold deionized water until neutral to obtain the final resin product.

[0054] Comparative Example 2 This comparative example only adds the second initiator, specifically: Weigh 2.5g of polyvinyl alcohol and 17.5g of sodium chloride and add them to a 1000mL three-necked flask. Then add 500mL of deionized water, heat to 50℃, and stir until completely dissolved. Add 2mL of 0.1% methylene blue solution and stir well to obtain the aqueous phase. Weigh 96.03g of methylstyrene and 3.97g of 63% divinylbenzene and add them to a beaker. Then weigh 0.6g of tert-butyl hydroperoxide and add it to the beaker. Mix well to obtain the oil phase. Adjust the stirring height, add the prepared oil phase to the aqueous phase, let stand for 10 minutes, start stirring, adjust the speed, control the particle size, and when the particle size is qualified (0.4-0.8 mm), raise the temperature to 84℃ and react for 6 hours. After the reaction is completed, raise the temperature to 92℃ and react for 5 hours. After the reaction is completed, cool the polymer to room temperature, filter the mother liquor, wash the precursor with deionized water until clear, and then dry at 100℃ for 5 hours to obtain the resin precursor.

[0055] Weigh 50g of resin precursor into a dry 1000mL three-necked flask, then add 430mL of concentrated sulfuric acid and stir for 15 minutes. Slowly add 40mL of 1,2-dichloroethane dropwise into the reaction system, raise the temperature to 130℃ for sulfonation reaction after 2 hours, and maintain the temperature for 4 hours. During the reaction, recover 1,2-dichloroethane. After the reaction is complete, cool to room temperature, and sequentially add dilute sulfuric acid of concentrations of 80%, 60%, 40%, 20%, and 5% for gradient acid washing. Reduce the density of the reaction mother liquor to 1.0g / mL through gradient acid washing. Wash with cold deionized water until neutral, then add 30% sulfuric acid, raise the temperature to 80℃, stir and wash for 2 hours, wash with 60℃ deionized water until near neutral, and finally wash with cold deionized water until neutral. Add 5% sulfuric acid, raise the temperature to 80℃, stir and wash for 4 hours, and finally wash with cold deionized water until neutral to obtain the final resin product.

[0056] Comparative Example 3 In this comparative example, benzoyl peroxide was used as the initiator, specifically: Weigh 2.5g of polyvinyl alcohol and 17.5g of sodium chloride and add them to a 1000mL three-necked flask. Then add 500mL of deionized water, heat to 50℃, and stir until completely dissolved. Add 2mL of 0.1% methylene blue solution and stir well to obtain the aqueous phase. Weigh 96.03g of methylstyrene and 3.97g of 63% divinylbenzene and add them to a beaker. Then weigh 0.6g of benzoyl peroxide and add it to the beaker. Mix well to obtain the oil phase. Adjust the stirring height, add the prepared oil phase to the aqueous phase, let stand for 10 minutes, start stirring, adjust the speed, control the particle size, and when the particle size is qualified (0.4-0.8 mm), raise the temperature to 84℃ and react for 6 hours. After the reaction is completed, raise the temperature to 92℃ and react for 5 hours. After the reaction is completed, cool the polymer to room temperature, filter the mother liquor, wash the precursor with deionized water until clear, and then dry at 100℃ for 5 hours to obtain the resin precursor.

[0057] Weigh 50g of resin precursor into a dry 1000mL three-necked flask, then add 430mL of concentrated sulfuric acid and stir for 15 minutes. Slowly add 40mL of 1,2-dichloroethane dropwise into the reaction system, raise the temperature to 130℃ for sulfonation reaction after 2 hours, and maintain the temperature for 4 hours. During the reaction, recover 1,2-dichloroethane. After the reaction is complete, cool to room temperature, and sequentially add dilute sulfuric acid of concentrations of 80%, 60%, 40%, 20%, and 5% for gradient acid washing. Reduce the density of the reaction mother liquor to 1.0g / mL through gradient acid washing. Wash with cold deionized water until neutral, then add 30% sulfuric acid, raise the temperature to 80℃, stir and wash for 2 hours, wash with 60℃ deionized water until near neutral, and finally wash with cold deionized water until neutral. Add 5% sulfuric acid, raise the temperature to 80℃, stir and wash for 4 hours, and finally wash with cold deionized water until neutral to obtain the final resin product.

[0058] The performance indicators of the resins obtained in Examples 1-6 and Comparative Examples 1-3 of this invention are shown in Table 1.

[0059] Table 1. Resin performance indicators for each embodiment and comparative example.

[0060] As can be seen from the above embodiments, the technical solution provided by this invention can prepare a catalytic resin for bisphenol A synthesis with high exchange capacity and high strength. To verify the technical effects achieved by this invention, three control samples were prepared: Comparative Example 1, Comparative Example 2, and Comparative Example 3. Based on Example 2, Comparative Example 1 added only initiator 1, without initiator 2, keeping the total amount of initiator unchanged; Comparative Example 2 added only initiator 2, without initiator 1, keeping the total amount of initiator unchanged; and Comparative Example 3 used conventional benzoyl peroxide as the initiator, keeping the total amount of initiator unchanged. The test results of various resin indicators show that using a single initiator or a conventional initiator did not significantly improve either the exchange capacity or the strength of the resin, and all performance indicators were lower than those in the embodiments of this invention.

[0061] The strong acid exchange capacity mentioned above refers to the total amount of dissociable acidic groups in a strong acid ion exchange resin. Moisture content refers to the amount of water absorbed by the ion exchange resin sample after centrifugation to remove external moisture from the particles, followed by drying to remove internal moisture; the moisture content is calculated from the decrease in mass. Permeation sphericity refers to the percentage of spherical particles obtained by applying permeation force to the ion exchange resin with a certain concentration of acid and alkali, followed by applying pressure and friction through tumbling, drying the resin until it can roll freely, and then separating it; the percentage of the total mass of the sample. The test methods for strong acid exchange capacity, moisture content, and permeation sphericity are respectively based on GB / T8144-2008, GB / T 5757-2008, and GB / T 12598—2023.

[0062] To further verify the catalytic effect of the resin prepared in this invention on the synthesis of bisphenol A, the following application test was conducted: The resin catalyst prepared in this invention was used to evaluate the bisphenol A synthesis reaction. The test samples were the resin catalysts prepared in Examples 1-6 of this invention, and the control samples were the resin catalysts prepared in Comparative Examples 1-3 of this invention. 50 mL of the test samples (Examples 1-6) and control samples (Comparative Examples 1-3) were placed in a catalytic reactor with an inner diameter of 25 mm. The catalysts were dehydrated with a mixture of 300 mL of phenol and water (95 wt% phenol) and repeated 3 times. Then, the catalysts were dehydrated with pure phenol until the water content in the effluent from the reaction device was less than 1 wt%. A mixture of acetone and phenol (phenol to acetone molar ratio 8:1) was added. The reaction temperature was 80 °C, the pressure was 0.26 MPa, and the feed volume hourly space velocity was 0.45 h⁻¹. The reaction was continuously run for 960 h for evaluation. The conversion rate of acetone, the selectivity of bisphenol A, and the sphericity of the resin before and after the test were measured. The test results are shown in the table below.

[0063] Table 2 Comparison of catalytic effects of resins in various examples and comparative examples

[0064] As shown in the table above, the resin sample prepared in the embodiments of the invention exhibits excellent catalytic performance and long-term stability in the synthesis of bisphenol A. After continuous operation for 960 hours, its sphericity remained above 98%, while the acetone conversion and bisphenol A selectivity were both greater than 98%. This superior performance is attributed to the key technological innovations in the preparation process of the resin, including the construction of the precursor structure, the sulfonation process, and the purification steps. The specific mechanism analysis is as follows: 1. Optimization of high strength and crosslinking structure of resin precursors The resin possesses high mechanical strength and a suitable cross-linking structure, ensuring its resistance to wear and breakage during long-term use, and providing an efficient diffusion path for reactant molecules.

[0065] The composite initiator strategy involves using a first initiator (such as tert-butyl peroxide-2-ethylhexanoate) to initiate polymerization at 83-85°C, forming a preliminary loose polymer network framework. Subsequently, a second initiator (such as cumene hydroperoxide) is added, and polymerization is further carried out at 91-93°C to enhance the crosslinking density and strengthen the network structure. This stepwise initiation process results in a more uniform and thorough polymerization reaction, forming a gel-type resin structure with a uniform crosslinked network and an appropriate ratio of working pores in the microporous region. This not only optimizes the diffusion and mass transfer efficiency of reactant molecules but also significantly improves the mechanical strength of the resin, making it more resistant to long-term wear and impact under reaction conditions.

[0066] 2. Construction of high-capacity, high-stability active sites The resin has a high density and uniformly distributed sulfonic acid group active sites, resulting in high catalytic activity and minimal loss of active groups during use, thus extending its lifespan.

[0067] High-temperature, short-time sulfonation process: Sulfonation is carried out at 125-135℃. Compared to the traditional low-temperature, long-time process, this high-temperature condition significantly accelerates the sulfonation reaction rate and shortens the process time. The high temperature allows sulfuric acid to more easily penetrate the swollen resin-based spheres, promoting the uniform distribution of sulfonic acid groups (-SO3H) inside and outside the resin, thereby introducing a higher density of active centers. Simultaneously, the high temperature promotes the formation of a more stable sulfonic acid group bond structure, effectively reducing the loss of active groups during use and ensuring high catalyst activity and long service life.

[0068] 3. Precisely controlled final product performance Through meticulous graded acid washing and post-treatment, a pure H-type cation exchange resin with moderate acidity and low impurity content was obtained, ensuring its high selectivity and stability.

[0069] Graded pickling post-treatment process: 1. Gradient pickling: Post-treatment using gradually changing acid concentrations (e.g., from high to low) avoids excessive expansion or contraction of the resin due to sudden concentration changes, thus protecting the resin's physical structure (e.g., pores and cross-linking degree) from damage. Simultaneously, it gradually removes residual concentrated sulfuric acid, sulfonation byproducts (e.g., sulfonates or sulfates), and unreacted organic matter from the reaction system, ensuring effective removal of impurities from the resin surface and interior; 2. First water wash: Immediately after gradient pickling, a water wash is performed to quickly dilute and remove most acid-soluble impurities, rinsing away residual acid and soluble small molecule impurities from the resin, preventing these impurities from redepositing in subsequent steps or affecting the resin's ion exchange capacity; 3. First acid wash: Acid washing is performed after the first water wash to further enhance the purification effect, ensuring the resin is completely converted to the desired hydrogen form (H). + 4. Secondary washing: Following the first acid wash, the secondary washing effectively removes residual acid and impurities introduced during the acid wash process, preventing acid accumulation that could lead to resin degradation; 5. Secondary acid wash: Repeated acid washing ensures thorough purification of the resin and uniformity of ionic form, enhancing the resin's chemical stability and service life, making it suitable for applications requiring high purity in bisphenol A synthesis; 6. Tertiary washing to neutral: Multiple washings until the effluent pH is neutral ensure that the resin has no acidic residue before use, achieving a stable neutral state, guaranteeing its storage safety and operational reliability, and avoiding interference with subsequent applications (catalytic reactions).

[0070] In summary, this invention constructs a high-strength resin skeleton using a composite initiator, achieves uniform implantation of high-capacity, stable active sites through high-temperature sulfonation, and combines this with stepwise purification to precisely control the acidic environment, all of which endow the resin catalyst with high activity, high selectivity, and exceptional stability.

[0071] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a sulfonic acid type cation exchange resin, characterized in that, Includes the following steps: S1: Dissolve the dispersant and co-dispersant in water until completely dissolved to obtain an aqueous phase; mix the polymerizable monomer, crosslinking agent and first initiator evenly to obtain an oil phase; add the oil phase to the aqueous phase to carry out a free radical polymerization reaction. After the reaction forms microspheres, add the second initiator and continue to heat the reaction to obtain a resin precursor. S2: The resin precursor is mixed and stirred with concentrated sulfuric acid, then a swelling agent is added, and a sulfonation reaction is carried out after heating. After the reaction is completed, the reactants are cooled to room temperature and subjected to gradient acid washing, first water washing, first acid washing, second water washing, second acid washing, and third water washing until neutral to obtain the sulfonic acid type cation exchange resin. The concentration of the acid solution in the first acid washing is greater than that in the second acid washing, and the temperature of the first and third water washings is lower than that of the second water washing.

2. The method for preparing a sulfonic acid type cation exchange resin according to claim 1, characterized in that, The first initiator is at least one of tert-butyl peroxide-2-ethylhexanoate and tert-butyl peroxide-3,5,5-trimethylhexanoate.

3. The method for preparing a sulfonic acid type cation exchange resin according to claim 1, characterized in that, The second initiator is at least one of cumene hydroperoxide, dicumene hydroperoxide, tert-butyl hydroperoxide, and p-menthol hydroperoxide.

4. The method for preparing a sulfonic acid type cation exchange resin according to claim 1, characterized in that, The total mass ratio of the polymer monomer and crosslinking agent to the mass ratio of the first initiator is 100:(0.2-1.0).

5. The method for preparing a sulfonic acid type cation exchange resin according to claim 1, characterized in that, The total mass ratio of the polymer monomer and crosslinking agent to the second initiator is 100:(0.1-0.5).

6. The method for preparing a sulfonic acid type cation exchange resin according to claim 1, characterized in that, The ratio of the resin precursor to concentrated sulfuric acid is 1 g: (7-10) mL.

7. The method for preparing a sulfonic acid type cation exchange resin according to claim 1, characterized in that, The sulfonation reaction is carried out at a temperature of 125-135°C for 3-5 hours.

8. The method for preparing a sulfonic acid type cation exchange resin according to claim 1, characterized in that, In the gradient pickling process, the pickling solution used is sulfuric acid with a mass percentage concentration of 80%, 60%, 40%, 20%, and 5% respectively; the pickling solution used in the first pickling process is sulfuric acid with a mass percentage concentration of 20%-30%; the pickling solution used in the second pickling process is sulfuric acid with a mass percentage concentration of 5%-10%; the resistivity of the water used in the first, second, and third water washes is ≥18.0 MΩ·cm; the temperature is room temperature in the first and third water washes, and the temperature of the second water wash is 60~70℃.

9. A sulfonic acid type cation exchange resin, characterized in that, It is prepared by the method described in any one of claims 1 to 8.

10. The application of the sulfonic acid type cation exchange resin as described in claim 9 in the synthesis of bisphenol A.

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