High-capacity acid-base ion exchange resin and preparation method thereof

Abstract

The invention belongs to the technical field of ion exchange resin, and discloses high-capacity acid-base ion exchange resin and a preparation method thereof. According to the acid-base ion exchange resin, methyl styrene is added to serve as an important monomer for synthesizing styrene resin, a new methyl group is introduced into a resin polymer, and chlorine is adopted for chlorinating the introduced methyl group, so that on one hand, the heat-resistant stability of the cation exchange resin can be improved; and on the other hand, new acid / alkali functional groups are further introduced by taking methyl as a bridge, and sulfonation / amination reaction is performed on new chloromethyl or methyl to introduce sulfonic acid groups and amino groups, so that the acid / alkali exchange capacity and thermal stability of the ion exchange resin are improved. The prepared high-capacity ion exchange resin has wider application in the fields of catalysis, adsorption and the like, can greatly improve the adsorption performance of heavy metal ions in wastewater, and has higher catalytic activity in chemical reactions such as esterification, hydration, condensation, polymerization and the like as a catalyst.

Description

A high-capacity acid-base ion exchange resin and its preparation method Technical Field

[0001] This invention belongs to the field of ion exchange resin technology, specifically a high-capacity acid-base ion exchange resin and its preparation method. Background Technology

[0002] Ion exchange resins are a class of high-molecular-weight polymers with ion exchange groups. They are chemically stable, have large molecular weights, high mechanical strength, and are insoluble in common acid, alkali, and organic solvents. They have wide applications in separation, purification, and catalysis. There are many types of ion exchange resins; based on the nature of their active groups, they can be classified into acidic cation exchange resins, basic anion exchange resins, chelating resins, amphoteric resins, and redox resins. Cation exchange resins, in particular, contain acidic groups (-SO3H) in their molecules, which can release H2O. + Acidic resins can be further classified into three categories: strongly acidic, weakly acidic, and mixed strongly-weakly acidic resins. Similarly, anion exchange resins contain basic groups and are basic, and can also be classified into three categories: strongly basic, weakly basic, and mixed strongly-weakly basic resins. Ion exchange resins are crucial for water treatment, such as removing heavy metal ions, nitrate ions, fluoride ions, and arsenic from water. They can also be used for acid-base catalytic reactions such as etherification, hydration, esterification, alkylation, condensation, decomposition, polymerization, and cyclization. Therefore, ion exchange resins have always been a research hotspot.

[0003] Patent CN110639624A discloses anion and cation exchange resins and a wastewater purification method for purifying caprolactam production wastewater. This patent uses a styrene-based monopolymer and a divinylbenzene-based monopolymer, which are then suspended and copolymerized with a porogen, initiator, and dispersant. The cation exchange resin is obtained through porogen extraction, drying, sieving, and sulfonation. The anion exchange resin is obtained by suspending and copolymerizing a styrene-based monopolymer and a divinylbenzene-based monopolymer with a porogen, initiator, and dispersant, followed by porogen extraction, drying, sieving, chlorination, and amination. This patent uses ethylstyrene, which limits the functional group capacity. The cation exchange resin uses concentrated sulfuric acid, and the anion exchange resin uses the highly carcinogenic chloromethyl ether. This results in high cost and significant risks, and it relies entirely on traditional benzene ring sulfonation and benzene ring chloromethylation, leading to a single route and limited performance. This technology has several problems and cannot be widely used.

[0004] In summary, while ion exchange resin technology is indeed in use, it still suffers from problems such as limited monomer synthesis routes, the use of toxic and highly polluting raw materials, and the limited performance of the prepared resins. Therefore, it is of great significance to develop an acid-base ion exchange resin with an innovative synthesis route that can double the exchange capacity, is green and efficient, has a high capacity, high thermal stability and wide distribution, and excellent comprehensive performance. Summary of the Invention

[0005] The purpose of this invention is to provide a high-capacity acid-base ion exchange resin. This resin introduces new methyl groups into the resin polymer by adding methylstyrene as an important monomer in the synthesis of styrene resin. The introduced methyl groups are then chlorinated with chlorine gas. This process improves the heat resistance of the cation exchange resin and allows the methyl groups to act as a bridge to further introduce new acid / base functional groups. The new chloromethyl or methyl groups are then sulfonated / amined to introduce sulfonic acid and amino groups, thereby increasing the acid / base exchange capacity of the ion exchange resin.

[0006] The objective of this invention is achieved through the following scheme: a high-capacity acid-base ion exchange resin, wherein the ion exchange resin is prepared by acid functionalization or alkali functionalization modification of a matrix resin; the matrix resin raw materials include 50-70% methylstyrene, 20-30% styrene, and 10-20% divinylbenzene; the acid functionalization modification raw materials include 0-30% chlorine and 70-100% sulfur trioxide; the alkali functionalization modification raw materials include 0-30% chlorine, 5-10% chloromethyl ether, and 60-90% trimethylamine.

[0007] At 120°C, chlorine reacts with the methylstyrene units on the polymer backbone via a side-chain chlorination reaction, converting the methyl group into benzyl chloride. Sulfur trioxide attacks site A on the benzene ring, undergoing an electrophilic substitution reaction to introduce sulfonic acid groups. Chlorine pre-activates the methyl group, allowing SO3 sulfonation to occur not only on the benzene ring but also at the activated methyl site, introducing a greater number of sulfonic acid groups than SO3 sulfonation alone. This results in the preparation of a high-capacity strong acid cation exchange resin. Under ultraviolet light, chlorine precisely attacks the methyl group, converting it into reactive benzyl chloride. Chloromethyl ether provides a -CH2Cl group, which attaches to site A on the benzene ring. Trimethylamine nucleophilically attacks all benzyl chloride groups, generating quaternary ammonium groups and maximizing the introduction of quaternary ammonium groups.

[0008] Preferably, the matrix resin comprises the following components in mass fractions: 55-65% methylstyrene, 28-30% styrene, and 10-12% divinylbenzene.

[0009] Methylstyrene, as the main monomer, introduces a dual functional group. The methyl group is chlorinated to -CH2Cl. The Cl atom is highly electronegative and generates a certain dipole-dipole interaction with the neighboring benzene ring or other atoms, forming physical cross-linking points within the molecule. This restricts the movement of the polymer chain, thereby increasing the glass transition temperature and thermal decomposition stability of the resin. Styrene copolymerizes with methylstyrene and participates in the formation of the polymer backbone. For cation exchange resins, the benzene ring undergoes an electrophilic substitution reaction under the action of a strong sulfonating agent, introducing a sulfonic acid group onto the benzene ring, thus endowing the resin with strong acidity. For anion exchange resins, the methyl groups on the side chains and the methyl groups on the benzene ring in the polymer are first chlorinated, and then undergo Friedel-Crafts alkylation with chloromethyl ether in the presence of a catalyst to attach a chloromethyl group. Then, it reacts with organic amines such as trimethylamine to generate quaternary ammonium groups, endowing the resin with more basic groups (i.e., strong basicity). Divinylbenzene creates cross-linking points, forming copolymer white spheres with a three-dimensional network structure, ensuring that the resin maintains the integrity of its physical morphology and does not dissolve or soften.

[0010] Preferably, the acid-functionalized modified raw material comprises the following components by mass fraction: chlorine 8-12% and sulfur trioxide 85-92%.

[0011] Chlorine gas preferentially attacks the methyl group on the methylstyrene unit, gradually converting it to benzyl chloride through a free radical substitution reaction. This benzyl chloride reacts with SO3 to generate a sulfonyl chloride intermediate, which ultimately hydrolyzes into a stable sulfonylmethyl functional group, increasing the resin's capacity. The traditional method involves sulfur trioxide directly attacking the benzene ring on the polystyrene polymer backbone, introducing sulfonic acid groups onto the benzene ring through an electrophilic substitution reaction. The introduction of methylstyrene monomer allows it to react with the benzyl chloride generated by chlorine gas, completing the final functionalization of the new sulfonation pathway. Simultaneously, the introduction of sulfonic acid groups onto both the benzene ring and the benzyl group enhances the acidity. The synergistic effect of these two methods through a dual-pathway sulfonation mechanism results in a significantly higher number of sulfonic acid groups per unit mass of resin compared to traditional single-benzene-ring sulfonation processes, leading to a higher acidity in the resin.

[0012] Preferably, the alkali-functionalized modified raw material comprises the following components in mass fractions: chloromethyl ether 8-10%, trimethylamine 68-75%, and chlorine 15-25%.

[0013] Under ambient temperature and ultraviolet light, chlorine gas undergoes homolytic cleavage, generating chlorine free radicals. These free radicals selectively attack the methyl groups on the methylstyrene unit, converting them into highly reactive benzyl chloride through a free radical substitution reaction. This creates a precursor for the amination reaction on the methyl group. Sufficient chlorine gas chlorinates a large number of methyl groups on the resin backbone, converting more methyl groups into benzyl chloride. Antimony chloride acts as a Lewis acid catalyst, activating chloromethyl ether. The resulting electrophilic reagent attacks the benzene ring of the polymer, undergoing Friedel-Crafts alkylation to attach chloromethyl groups to the benzene ring, efficiently introducing sites. Trimethylamine acts as a nucleophile, simultaneously attacking the benzyl chloride generated through both pathways. The polymer CH2Cl produced by methyl chlorination and the polymer produced by chloromethylation of the benzene ring both generate strongly basic quaternary ammonium groups, resulting in higher base strength.

[0014] This invention discloses a method for preparing a high-capacity acid-base ion exchange resin, comprising the following steps: S1, using a polyvinyl alcohol aqueous solution as the reaction base liquid, adding a catalyst; adding methylstyrene, styrene, divinylbenzene and toluene as a porogen to the initiator peroxybenzoyl in sequence, stirring to form a raw material mixture, adding it dropwise to the polyvinyl alcohol reaction base liquid, heating in a rising section, cooling and filtering after completion, washing with water and alcohol, and drying to obtain a resin polymer matrix; S2, using the resin polymer matrix to prepare an acidic ion exchange resin through a sulfonation reaction; using the resin polymer matrix to prepare a basic ion exchange resin through chlorination, chloromethylation and amination reactions.

[0015] Preferably, the reaction conditions in step S1 are: heating to 70°C and holding for 2 hours, holding at 85°C for 2 hours, holding at 95°C for 1 hour, pressure of 0.01-0.50 MPa, and reaction time of 2-8 hours.

[0016] Benzoyl peroxide (BPO), as an initiator, decomposes upon heating to generate free radicals, initiating chain polymerization. Its decomposition rate increases sharply with increasing temperature. If the reaction is carried out at high temperature immediately, benzoyl peroxide will decompose rapidly, generating a large number of free radicals, leading to explosive polymerization. The heating conditions in the ascending stage are mild, avoiding violent exothermic reactions, which is conducive to the formation of spherical resins with uniform particle size. 70℃ is conducive to the stable growth of the polymer crosslinking network, laying the foundation for a uniform network structure. 85℃ accelerates the decomposition and polymerization reaction rate of BPO. The three-dimensional crosslinking network is mainly solidified at this stage. At 95℃, the remaining initiator and monomers are completely consumed, making the polymerization reaction more complete. High temperature helps the movement of polymer chain segments, relaxes internal stress, and stabilizes the network structure.

[0017] Preferably, the catalyst in step S1 is one or more of cumene peroxide, azobutyronitrile, or ammonium persulfate; and the solvent is one or more of toluene, xylene, sec-butanol, or butyl acetate.

[0018] Cumene peroxide decomposes mildly at 70-85℃, ensuring stable nucleation and growth. At 95℃, it decomposes efficiently, ensuring complete cross-linking and facilitating the formation of a stable network with higher cross-linking density, thus improving the mechanical strength and thermal stability of the resin. Azobisisobutyronitrile (AIB) does not produce acidic substances and has little impact on the pH of the reaction system, avoiding potential side reactions under acidic conditions and contributing to a higher purity resin matrix. The nitrogen gas produced during decomposition forms tiny bubbles within the polymer phase, acting as an in-situ porogen and synergistically with added porogens to help form a richer and more uniform pore structure. Ammonium persulfate polymerizes from the outside in, helping to form a denser and tougher shell, significantly improving the mechanical strength of the resin white spheres. Toluene and xylene have small pore sizes, providing a large specific surface area and more attachment sites. sec-butanol and butyl acetate can construct fast transport channels and reduce steric hindrance.

[0019] Preferably, the acidic cation exchange resin in step S2 is specifically prepared by reacting the resin polymer matrix with chlorine and sulfur trioxide at 120°C and 0.1 MPa for 4 hours, followed by washing to obtain a sulfonic acid type cation exchange resin.

[0020] At 120℃, chlorine molecules gain enough energy to homolytically cleave and generate chlorine free radicals, which undergo free radical substitution reactions to transform into highly reactive benzyl chloride. 120℃ is much higher than the boiling point of SO3, ensuring that SO3 is in a gaseous state, increasing molecular kinetic energy, promoting its diffusion into the resin matrix, and accelerating the rate of electrophilic substitution reactions with the benzene ring.

[0021] Preferably, the alkaline anion exchange resin in step S2 is prepared by: reacting the resin polymer matrix with chlorine gas, using antimony chloride as a catalyst, reacting the chlorinated resin matrix with chloromethyl ether to form a benzene ring chloromethylation, adding trimethylamine to form an amination reaction, and washing to obtain the alkaline ion exchange resin.

[0022] The use of ultraviolet light initiation provides milder and more controllable conditions, better suppressing side reactions and ensuring the specificity and efficiency of the reaction. Antimony chloride, as a strong Lewis acid catalyst, reacts with chloromethyl ether to generate a highly active electrophilic agent that attacks the polymer benzene ring, resulting in Friedel-Crafts alkylation to attach chloromethyl groups to the benzene ring. Trimethylamine, as a nucleophile, simultaneously attacks benzyl chloride generated through two pathways. The numerous reaction sites introduced by the dual pathways are converted into ultra-high exchange capacity after amination.

[0023] Preferably, the chlorination reaction conditions in step S2 are: in an ultraviolet environment, the reaction temperature is 20-26℃; the benzene ring chloromethylation reaction conditions are: the reaction temperature is 40-60℃, the reaction time is 20-24h; and the amination reaction conditions are: the reaction temperature is 40-55℃, the reaction time is 10-13h.

[0024] The beneficial effects of the present invention are as follows: (1) Methylstyrene is selected as an important monomer for the synthesis of styrene resin. By adding new groups as a bridge to introduce more acid and base functional groups, the acid / base exchange capacity of the ion exchange resin can be greatly improved; (2) While introducing methyl groups and synthesizing new styrene resin, the chlorination technology can be used to further improve the thermal stability of the ion exchange resin; (3) The high-capacity ion exchange resin prepared by the present invention has a wider range of applications in catalysis, adsorption and other fields. It can greatly improve the adsorption performance of heavy metal ions in wastewater. Moreover, as a catalyst, it has higher catalytic activity in chemical reactions such as esterification, hydration, condensation and polymerization. Detailed Implementation

[0025] Example 1: This example provides a resin polymer matrix, specifically comprising the following components by mass fraction: 60% methylstyrene, 30% styrene, and 10% divinylbenzene.

[0026] This embodiment also provides a method for preparing a resin polymer matrix, specifically including the following steps: preparing a polyvinyl alcohol aqueous solution as the reaction substrate, and adding cumene peroxide as a catalyst; sequentially adding methylstyrene, styrene, divinylbenzene, and toluene as a pore-forming agent to the initiator benzoyl peroxide, stirring to form a raw material mixture; under uniform stirring, adding the raw material mixture dropwise to the polyvinyl alcohol aqueous reaction substrate, heating at atmospheric pressure to 70°C and maintaining for 2 hours, 85°C and maintaining for 2 hours, and 95°C and maintaining for 1 hour. After the reaction is completed, cooling, filtering, washing with water, washing with ethanol, and then drying in a fume hood or oven to obtain the resin polymer matrix.

[0027] This embodiment also provides a method for preparing an acidic cation exchange resin, which specifically includes the following steps: reacting the prepared resin polymer matrix with 10% chlorine and 90% sulfur trioxide by mass, at a reaction temperature of 120 ℃, a pressure of 0.1 MPa, and a reaction time of 4.0 h to obtain a chlorinated sulfonic acid type cation exchange resin; after the reaction is completed, the resin is washed.

[0028] This embodiment also provides a method for preparing a basic anion exchange resin, specifically including the following steps: The prepared resin polymer matrix is ​​subjected to a chlorination reaction of the methyl groups on the benzene ring of the resin backbone under ultraviolet light at 25°C, with chlorine gas introduced (material mass fraction: 10% chloromethyl ether, 70% trimethylamine, 20% chlorine gas). Using antimony chloride as a catalyst, the chlorinated resin matrix and chloromethyl ether undergo a chloromethylation reaction of the benzene ring at 50°C for 22 hours. Then, trimethylamine is used as a raw material for an amination reaction to obtain the basic ion exchange resin at 50°C for 12 hours. After the reaction is complete, the resin is washed.

[0029] Example 2: This example provides a resin polymer matrix, specifically comprising the following components by mass fraction: 50% methylstyrene, 30% styrene, and 20% divinylbenzene.

[0030] This embodiment also provides a method for preparing a resin polymer matrix, specifically including the following steps: preparing a polyvinyl alcohol aqueous solution as the reaction substrate, and adding cumene peroxide as a catalyst; sequentially adding methylstyrene, styrene, divinylbenzene, and toluene as a pore-forming agent to the initiator benzoyl peroxide, stirring to form a raw material mixture; under uniform stirring, adding the raw material mixture dropwise to the polyvinyl alcohol aqueous reaction substrate, heating at atmospheric pressure to 70°C and maintaining for 2 hours, 85°C and maintaining for 2 hours, and 95°C and maintaining for 1 hour. After the reaction is completed, cooling, filtering, washing with water, washing with ethanol, and then drying in a fume hood or oven to obtain the resin polymer matrix.

[0031] This embodiment also provides a method for preparing an acidic cation exchange resin, which specifically includes the following steps: reacting the prepared resin polymer matrix with 10% chlorine and 90% sulfur trioxide by mass, at a reaction temperature of 120 ℃, a pressure of 0.1 MPa, and a reaction time of 4.0 h to obtain a chlorinated sulfonic acid type cation exchange resin; after the reaction is completed, the resin is washed.

[0032] This embodiment also provides a method for preparing a basic anion exchange resin, specifically including the following steps: The prepared resin polymer matrix is ​​subjected to a chlorination reaction of the methyl groups on the benzene ring of the resin backbone under ultraviolet light at 25°C, with chlorine gas introduced (material mass fraction: 10% chloromethyl ether, 70% trimethylamine, 20% chlorine gas). Using antimony chloride as a catalyst, the chlorinated resin matrix is ​​subjected to a chloromethylation reaction with chloromethyl ether at 50°C for 22 hours. Then, an amination reaction is performed using trimethylamine as a raw material to obtain the basic ion exchange resin at 50°C for 12 hours. After the reaction, the resin is washed.

[0033] The difference between this embodiment and Example 1 is that the ratio of the resin polymer matrix is ​​changed to 50% methylstyrene, 30% styrene, and 20% divinylbenzene.

[0034] Example 3: This example provides a resin polymer matrix, specifically comprising the following components by mass fraction: 70% methylstyrene, 20% styrene, and 10% divinylbenzene.

[0035] This embodiment also provides a method for preparing a resin polymer matrix, specifically including the following steps: preparing a polyvinyl alcohol aqueous solution as the reaction substrate, and adding cumene peroxide as a catalyst; sequentially adding methylstyrene, styrene, divinylbenzene, and toluene as a pore-forming agent to the initiator benzoyl peroxide, stirring to form a raw material mixture; under uniform stirring, adding the raw material mixture dropwise to the polyvinyl alcohol aqueous reaction substrate, heating at atmospheric pressure to 70°C and maintaining for 2 hours, 85°C and maintaining for 2 hours, and 95°C and maintaining for 1 hour. After the reaction is completed, cooling, filtering, washing with water, washing with ethanol, and then drying in a fume hood or oven to obtain the resin polymer matrix.

[0036] This embodiment also provides a method for preparing an acidic cation exchange resin, which specifically includes the following steps: reacting the prepared resin polymer matrix with 10% chlorine and 90% sulfur trioxide by mass, at a reaction temperature of 120 ℃, a pressure of 0.1 MPa, and a reaction time of 4.0 h to obtain a chlorinated sulfonic acid type cation exchange resin; after the reaction is completed, the resin is washed.

[0037] This embodiment also provides a method for preparing a basic anion exchange resin, specifically including the following steps: The prepared resin polymer matrix is ​​subjected to a chlorination reaction of the methyl groups on the benzene ring of the resin backbone under ultraviolet light at 25°C, with chlorine gas introduced (material mass fraction: 10% chloromethyl ether, 70% trimethylamine, 20% chlorine gas). Using antimony chloride as a catalyst, the chlorinated resin matrix is ​​subjected to a chloromethylation reaction with chloromethyl ether at 50°C for 22 hours. Then, an amination reaction is performed using trimethylamine as a raw material to obtain the basic ion exchange resin at 50°C for 12 hours. After the reaction, the resin is washed.

[0038] The difference between this embodiment and Example 1 is that the ratio of the resin polymer matrix is ​​changed to 70% methylstyrene, 20% styrene, and 10% divinylbenzene.

[0039] Example 4: This example provides a resin polymer matrix, specifically comprising the following components by mass fraction: 60% methylstyrene, 30% styrene, and 10% divinylbenzene.

[0040] This embodiment also provides a method for preparing a resin polymer matrix, specifically including the following steps: preparing a polyvinyl alcohol aqueous solution as the reaction substrate, and adding cumene peroxide as a catalyst; sequentially adding methylstyrene, styrene, divinylbenzene, and toluene as a pore-forming agent to the initiator benzoyl peroxide, stirring to form a raw material mixture; under uniform stirring, adding the raw material mixture dropwise to the polyvinyl alcohol aqueous reaction substrate, heating at atmospheric pressure to 70°C and maintaining for 2 hours, 85°C and maintaining for 2 hours, and 95°C and maintaining for 1 hour. After the reaction is completed, cooling, filtering, washing with water, washing with ethanol, and then drying in a fume hood or oven to obtain the resin polymer matrix.

[0041] This embodiment also provides a method for preparing an acidic cation exchange resin, which specifically includes the following steps: reacting the prepared resin polymer matrix with 30% chlorine and 70% sulfur trioxide by mass fraction at a reaction temperature of 120 ℃, a pressure of 0.1 MPa, and a reaction time of 4.0 h to obtain a chlorinated sulfonic acid type cation exchange resin; after the reaction is completed, the resin is washed.

[0042] This embodiment also provides a method for preparing a basic anion exchange resin, specifically including the following steps: The prepared resin polymer matrix is ​​subjected to a chlorination reaction of the methyl groups on the benzene ring of the resin backbone under ultraviolet light at 25°C, with chlorine gas introduced (material mass fraction: 10% chloromethyl ether, 60% trimethylamine, 30% chlorine gas). Using antimony chloride as a catalyst, the chlorinated resin matrix is ​​subjected to a chloromethylation reaction with chloromethyl ether at 50°C for 22 hours. Then, an amination reaction is performed using trimethylamine as a raw material to obtain the basic ion exchange resin at 50°C for 12 hours. After the reaction is complete, the resin is washed.

[0043] The difference between this embodiment and Example 1 is that the chlorine mass fraction used to prepare the cation exchange resin is 30% and the sulfur trioxide mass fraction is 70%; while the antimony chloride mass fraction used to prepare the anion exchange resin is 10%, the trimethylamine mass fraction is 60%, and the chlorine mass fraction is 30%.

[0044] Example 5: This example provides a resin polymer matrix, specifically comprising the following components by mass fraction: 60% methylstyrene, 30% styrene, and 10% divinylbenzene.

[0045] This embodiment also provides a method for preparing a resin polymer matrix, specifically including the following steps: preparing a polyvinyl alcohol aqueous solution as the reaction substrate, and adding cumene peroxide as a catalyst; sequentially adding methylstyrene, styrene, divinylbenzene, and toluene as a pore-forming agent to the initiator benzoyl peroxide, stirring to form a raw material mixture; under uniform stirring, adding the raw material mixture dropwise to the polyvinyl alcohol aqueous reaction substrate, heating at atmospheric pressure to 70°C and maintaining for 2 hours, 85°C and maintaining for 2 hours, and 95°C and maintaining for 1 hour. After the reaction is completed, cooling, filtering, washing with water, washing with ethanol, and then drying in a fume hood or oven to obtain the resin polymer matrix.

[0046] This embodiment also provides a method for preparing an acidic cation exchange resin, which specifically includes the following steps: reacting the prepared resin polymer matrix with 1% chlorine and 99% sulfur trioxide by mass, at a reaction temperature of 120 ℃, a pressure of 0.1 MPa, and a reaction time of 4.0 h to obtain a chlorinated sulfonic acid type cation exchange resin; after the reaction is completed, the resin is washed.

[0047] This embodiment also provides a method for preparing a basic anion exchange resin, specifically including the following steps: The prepared resin polymer matrix is ​​subjected to a chlorination reaction of the methyl groups on the benzene ring of the resin backbone under ultraviolet light at 25°C, with chlorine gas introduced (material mass fraction: 10% chloromethyl ether, 89% trimethylamine, 1% chlorine gas). Using antimony chloride as a catalyst, the chlorinated resin matrix is ​​subjected to a chloromethylation reaction with chloromethyl ether at 50°C for 22 hours. Then, an amination reaction is performed using trimethylamine as a raw material to obtain the basic ion exchange resin at 50°C for 12 hours. After the reaction, the resin is washed.

[0048] The difference between this embodiment and Example 1 is that the chlorine gas used to prepare the cation exchange resin has a mass fraction of 1% and the sulfur trioxide mass fraction is 99%; while the antimony chloride used to prepare the anion exchange resin has a mass fraction of 10%, trimethylamine 89%, and chlorine 1%.

[0049] Comparative Example 1: This comparative example provides a resin polymer matrix, specifically comprising the following components by mass fraction: 0% methylstyrene, 70% styrene, and 30% divinylbenzene.

[0050] This comparative example also provides a method for preparing a resin polymer matrix, specifically including the following steps: preparing a polyvinyl alcohol aqueous solution as the reaction substrate, and adding cumene peroxide as a catalyst; sequentially adding methylstyrene, styrene, divinylbenzene, and toluene as a porogen to the initiator benzoyl peroxide, stirring to form a raw material mixture; under uniform stirring, adding the raw material mixture dropwise to the polyvinyl alcohol aqueous reaction substrate, heating at atmospheric pressure to 70°C and maintaining for 2 hours, 85°C and maintaining for 2 hours, and 95°C and maintaining for 1 hour. After the reaction is completed, cooling, filtering, washing with water and ethanol, and then drying in a fume hood or oven to obtain the resin polymer matrix.

[0051] This comparative example also provides a method for preparing an acidic cation exchange resin, specifically including the following steps: reacting the prepared resin polymer matrix with 10% chlorine and 90% sulfur trioxide by mass, at a reaction temperature of 120 ℃, a pressure of 0.1 MPa, and a reaction time of 4.0 h to obtain a chlorinated sulfonic acid type cation exchange resin; after the reaction is completed, the resin is washed.

[0052] This comparative example also provides a method for preparing a basic anion exchange resin, specifically including the following steps: The prepared resin polymer matrix is ​​subjected to chlorination reaction of the methyl groups on the benzene ring of the resin backbone under ultraviolet light at 25°C, with chlorine gas introduced (material mass fraction: 10% chloromethyl ether, 70% trimethylamine, 20% chlorine gas). Using antimony chloride as a catalyst, the chlorinated resin matrix is ​​subjected to a chloromethylation reaction with chloromethyl ether at 50°C for 22 h. Then, an amination reaction is performed using trimethylamine as a raw material to obtain the basic ion exchange resin at 50°C for 12 h. After the reaction, the resin is washed.

[0053] The difference between this comparative example and Example 1 is that the ratio of the resin polymer matrix is ​​changed to 0% methylstyrene, 70% styrene, and 30% divinylbenzene.

[0054] Comparative Example 2: This comparative example provides a resin polymer matrix, specifically comprising the following components by mass fraction: 60% methylstyrene, 30% styrene, and 10% divinylbenzene.

[0055] This comparative example also provides a method for preparing a resin polymer matrix, specifically including the following steps: preparing a polyvinyl alcohol aqueous solution as the reaction substrate, and adding cumene peroxide as a catalyst; sequentially adding methylstyrene, styrene, divinylbenzene, and toluene as a porogen to the initiator benzoyl peroxide, stirring to form a raw material mixture; under uniform stirring, adding the raw material mixture dropwise to the polyvinyl alcohol aqueous reaction substrate, heating at atmospheric pressure to 70°C and maintaining for 2 hours, 85°C and maintaining for 2 hours, and 95°C and maintaining for 1 hour. After the reaction is completed, cooling, filtering, washing with water and ethanol, and then drying in a fume hood or oven to obtain the resin polymer matrix.

[0056] This comparative example also provides a method for preparing an acidic cation exchange resin, specifically including the following steps: reacting the prepared resin polymer matrix with 0% chlorine and 100% sulfur trioxide by mass, at a reaction temperature of 120 ℃, a pressure of 0.1 MPa, and a reaction time of 4.0 h to obtain a chlorinated sulfonic acid type cation exchange resin; after the reaction is completed, the resin is washed.

[0057] This comparative example also provides a method for preparing a basic anion exchange resin, specifically including the following steps: The prepared resin polymer matrix is ​​subjected to chlorination reaction of the methyl groups on the benzene ring of the resin backbone under ultraviolet light at 25°C, with chlorine gas introduced (material mass fraction: chloromethyl ether 10%, trimethylamine 90%, chlorine gas 0%). Using antimony chloride as a catalyst, the chlorinated resin matrix and chloromethyl ether undergo a chloromethylation reaction of the benzene ring at 50°C for 22 h. Then, trimethylamine is used as a raw material for an amination reaction to obtain the basic ion exchange resin at 50°C for 12 h. After the reaction, the resin is washed.

[0058] The difference between this comparative example and Example 1 is that the chlorine mass fraction used to prepare the cation exchange resin is 0%, the sulfur trioxide mass fraction is 100%, and the antimony chloride mass fraction, trimethylamine mass fraction, and chlorine mass fraction used to prepare the anion exchange resin are 10%, 90%, and 0%.

[0059] Experimental Example 1: The results of the acid-base ion exchange resins prepared in Examples 1-5 and Comparative Examples 1-2 are shown in Table 1 below.

[0060] Cation exchange resin exchange capacity determination: Accurately weigh 0.1000 g ± 0.0005 g of pretreated sulfonic acid type cation exchange resin into an Erlenmeyer flask, precisely add 100.00 mL of 0.1 mol / L NaCl standard solution, stir at room temperature for 2 h, and then titrate with 0.04 mol / L NaOH standard solution, using phenolphthalein as an indicator. Titrate with NaOH standard solution until the pink color persists for 30 s, which is the endpoint. Record the volume of NaOH consumed and calculate H2. +The molar amount is used to obtain the acid exchange capacity data of the resin.

[0061] Anion exchange resin exchange capacity determination: Weigh approximately 2.5 g ± 0.001 g of a strongly basic anion exchange resin sample and place it in a dry, stoppered Erlenmeyer flask. Pipette 100 mL of 0.5 mol / L sodium sulfate solution into the Erlenmeyer flask containing the sample, shake well, and seal the flask tightly. Soak at room temperature for 20 min. Pipette 25 mL of the soaking solution (without removing resin particles) from the stoppered Erlenmeyer flask and place it in the Erlenmeyer flask. Add 50 mL of pure water and 3 drops of methyl red-methylene blue mixed indicator solution. Titrate with 0.1 mol / L hydrochloric acid standard solution until a faint purple-red color persists for 15 seconds; this is the endpoint. Record the volume of hydrochloric acid solution consumed; this is the acid exchange capacity data of the resin.

[0062] Maximum heat resistance temperature test: Take 0.0100g of pretreated dry resin sample, heat it to 500℃ in a nitrogen atmosphere at a heating rate of 15℃ / min, and perform thermogravimetric analysis. Record the temperature at which the mass begins to be significantly lost.

[0063] Table 1. Exchange capacity and maximum heat resistance temperature data of ion exchange resins in Examples 1-5 and Comparative Examples 1-2 Example 1: The high methylstyrene content provides numerous reaction sites, while the benzene ring also provides sites. This dual functionalization maximizes the number of sites, increasing resin capacity. Styrene synergistically ensures the basic benzene ring sites, guaranteeing the resin's fundamental functions. Divinylbenzene (DVB) provides three-dimensional network rigidity, constructing a three-dimensional network supporting high-density functional groups, providing high mechanical strength and thermal stability. For acidic cation exchange resins, chlorine gas attacks the methyl group, activating it into highly reactive benzyl chloride, opening a second channel for synergistic reaction with sulfur trioxide, forming new sulfonic acid sites and generating more protons (H). + This increases the resin capacity. For basic anion exchange resins, Cl2 generates free radicals that attack methyl groups, converting them into benzyl chloride. Under the action of a catalyst, the benzene ring undergoes chloromethylation, introducing benzyl chloride. Trimethylamine molecules simultaneously attack the benzyl chloride produced by dual functionalization, converting it into a quaternary ammonium group, thereby increasing the resin's basic capacity and improving its thermal stability.

[0064] Example 2 (50% methylstyrene, 30% styrene, 20% divinylbenzene): Increasing the DVB content from 10% to 20% resulted in an overly dense crosslinking network, which hindered the diffusion of anions and cations into the resin and their exchange with all functional groups, leading to a decrease in the measured capacity, but with minimal impact on thermal stability.

[0065] Example 3 (70% methylstyrene, 20% styrene, 10% divinylbenzene): Styrene provides sulfonation and chloromethylation sites. Its proportion is too low, which leads to a reduction in the number of functional groups in the traditional pathway. Although the number of methyl pathway sites increases, the chlorination and subsequent transformation of methyl groups are incomplete. The newly introduced functional groups have low effectiveness, resulting in a decrease in total capacity. The proportion of methylstyrene is too high, which reduces the regularity and rigidity of the polymer backbone, resulting in a decrease in thermal stability compared to Example 1.

[0066] Example 4 (acidic cation exchange resin: 30% chlorine, 70% sulfur trioxide; basic anion exchange resin: 10% chloromethyl ether, 60% trimethylamine, 30% chlorine): Increasing the chlorine ratio enhances the chlorination activation of methyl groups, ensuring sufficient reaction in the second pathway. Simultaneously, chlorine exerts additional cross-linking effects on the polymer backbone, improving resin stability. However, excessive chlorine content can substitute benzene rings, affecting capacity; therefore, the capacity is slightly lower than in Example 1.

[0067] Example 5 (acidic cation exchange resin: 1% chlorine, 99% sulfur trioxide; basic anion exchange resin: 10% chloromethyl ether, 89% trimethylamine, 1% chlorine): The chlorine ratio is extremely low, the second functionalized methyl pathway is almost closed, and it mainly relies on the traditional benzene ring pathway, resulting in a significant reduction in capacity. The thermal stability of the resin mainly depends on the body itself.

[0068] Comparative Example 1 (0% methylstyrene, 70% styrene, 30% divinylbenzene): Completely free of methylstyrene, the second functionalized methyl pathway is also closed, and functional groups can only be introduced through traditional methods, resulting in a traditional resin formulation with a significant decrease in capacity.

[0069] Comparative Example 2 (acidic cation exchange resin: chlorine 0%, sulfur trioxide 100%, basic anion exchange resin: chloromethyl ether 10%, trimethylamine 90%, chlorine 0%): No chlorine was introduced at all, the methyl group could not be activated, the second functionalized methyl pathway was closed, it was essentially a single-pathway functionalization, the thermal stability was reduced to the minimum level, which proved the importance of chlorine.

[0070] In summary, Example 1, using 60% methylstyrene, 30% styrene, and 10% divinylbenzene to prepare a resin polymer matrix, reacted with 10% chlorine and 90% sulfur trioxide by mass fraction to generate a sulfonic acid-type cation exchange resin. After the reaction, the resin was washed. The optimal example is the formation of an alkaline ion exchange resin using 10% antimony chloride, 70% trimethylamine, and 20% chlorine by mass fraction, with antimony chloride as a catalyst.

Claims

1. A high-capacity acid-base ion exchange resin, characterized in that, The ion exchange resin is prepared by acid functionalization or alkali functionalization of a matrix resin; the matrix resin raw materials include 50-70% methylstyrene, 20-30% styrene and 10-20% divinylbenzene; the acid functionalization raw materials include 0-30% chlorine and 70-100% sulfur trioxide; the alkali functionalization raw materials include 0-30% chlorine, 5-10% chloromethyl ether and 60-90% trimethylamine.

2. The high-capacity acid-base ion exchange resin according to claim 1, characterized in that, The matrix resin comprises the following components by mass fraction: 55-65% methylstyrene, 28-30% styrene, and 10-12% divinylbenzene.

3. The high-capacity acid-base ion exchange resin according to claim 1, characterized in that, The acid-functionalized modified raw material comprises the following components by mass fraction: chlorine 8-12%, sulfur trioxide 85-92%.

4. The high-capacity acid-base ion exchange resin according to claim 1, characterized in that, The alkali-functionalized modified raw material comprises the following components by mass fraction: chloromethyl ether 8-10%, trimethylamine 68-75%, and chlorine 15-25%.

5. A method for preparing the high-capacity acid-base ion exchange resin according to any one of claims 1-4, characterized in that, The process includes the following steps: S1, using a polyvinyl alcohol aqueous solution as the reaction substrate, a catalyst is added; methylstyrene, styrene, divinylbenzene and toluene, a porogen, are added sequentially to the initiator benzoyl peroxide, and stirred to form a raw material mixture, which is then added dropwise to the polyvinyl alcohol reaction substrate. The mixture is heated in a rising section, and after completion, cooled, filtered, washed with water and alcohol, and dried to obtain a resin polymer matrix; S2, the resin polymer matrix is ​​converted into an acidic cation exchange resin through a sulfonation reaction; the resin polymer matrix is ​​converted into a basic anion exchange resin through chlorination, chloromethylation and amination reactions.

6. The method for preparing the high-capacity acid-base ion exchange resin according to claim 5, characterized in that, The reaction conditions in step S1 are as follows: heating to 70°C and holding for 2 hours, holding at 85°C for 2 hours, holding at 95°C for 1 hour, pressure of 0.01-0.50 MPa, and reaction time of 2-8 hours.

7. The method for preparing the high-capacity acid-base ion exchange resin according to claim 5, characterized in that, The catalyst in step S1 is one or more of cumene peroxide, azobutyronitrile, or ammonium persulfate; the solvent is one or more of toluene, xylene, sec-butanol, or butyl acetate.

8. The method for preparing the high-capacity acid-base ion exchange resin according to claim 5, characterized in that, The specific steps of the acidic cation exchange resin in step S2 are as follows: the resin polymer matrix is ​​reacted with chlorine and sulfur trioxide at 120°C and 0.1 MPa for 4 hours, and then washed to obtain sulfonic acid type cation exchange resin.

9. The method for preparing the high-capacity acid-base ion exchange resin according to claim 5, characterized in that, The specific steps of the basic anion exchange resin in step S2 are as follows: the resin polymer matrix is ​​subjected to chlorination reaction with chlorine gas, antimony chloride is used as a catalyst, the chlorinated resin matrix is ​​subjected to benzene ring chloromethylation with chloromethyl ether, trimethylamine is added to carry out amination reaction, and the resin is washed to obtain the basic ion exchange resin.

10. The method for preparing the high-capacity acid-base ion exchange resin according to claim 5 or 9, characterized in that, The chlorination reaction conditions in step S2 are: in an ultraviolet environment, the reaction temperature is 20-26℃; the benzene ring chloromethylation reaction conditions are: the reaction temperature is 40-60℃, the reaction time is 20-24h; and the amination reaction conditions are: the reaction temperature is 40-55℃, the reaction time is 10-13h.

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