A styrene-based macroporous strong base anionic resin and preparation method thereof

Abstract

The present invention relates to the technical field of polymer compounds obtained by reacting only carbon-carbon unsaturated bonds, and in particular to a styrene-based macroporous strong base anion resin and a preparation method thereof. The anion exchange resin in the present invention is obtained by chloromethylating a styrene-based white ball to obtain a chloromethylated resin, and then introducing a piperidine ring connected to an alkyl chain into its skeleton for cross-linking. Compared with the prior art, the styrene-based macroporous strong base resin obtained by the present invention has better high temperature stability and good adsorption capacity for nitrates and heavy metals.

Description

Technical Field

[0001] This invention relates to the field of polymer compounds obtained by reacting only carbon-carbon unsaturated bonds, and particularly to a styrene-based macroporous strong base anion resin and its preparation method. Background Technology

[0002] Ion exchange resins are special polymeric materials with ion exchange capabilities, containing ion exchange groups embedded in their structure. These resins can be classified according to the type of cross-linking polymer they use, including styrene-based, acrylic-based, phenolic-based, epoxy-based, vinylpyridine-based, urea-formaldehyde-based, and vinyl chloride-based resins. They also come in two forms: gel-type and macroporous-type. Furthermore, based on the properties of the functional groups in the resin, they can be further classified into seven types: strongly acidic, weakly acidic, strongly basic, weakly basic, chelating, amphoteric, and redox. The applications of these resins are very broad, including water treatment, pharmaceuticals, catalysis, decolorization, analysis, and the nuclear industry. Styrene-type anion exchange resins have wide applications in industrial water treatment and ion coordination technologies. In recent years, their applications have expanded to biochemistry and pharmaceutical engineering, and they have received increasing attention.

[0003] CN201510498788.8 discloses a strongly basic styrene-based anion exchange resin, the formulation of which, by weight, comprises 19-40 parts isoamyl alcohol, 6-10 parts paraformaldehyde, 38-63 parts thionyl chloride, 9-11 parts cross-linked polystyrene resin, 16-30 parts tin tetrachloride, 55-87 parts dichloromethane, 20-35 parts trimethylamine, 8-15 parts deionized water, 0.4-0.8 parts sodium chloride, and 24-60 parts dioxane. This invention also provides a method for preparing the above-mentioned strongly basic styrene-based anion exchange resin, using isoamyl alcohol, paraformaldehyde, and thionyl chloride as basic raw materials to synthesize isopentyl chloromethyl ether, which is used for the chloromethylation of cross-linked polystyrene to obtain chloromethylated cross-linked polystyrene. The chloromethylated cross-linked polystyrene is then amination to obtain a light yellow, transparent, strongly basic anion exchange resin. This invention solves the environmental pollution and production safety problems in the traditional chloromethylation process.

[0004] CN200810022706.2 relates to a method for preparing a strong base anion exchange resin with long spacer arms, belonging to the field of ion exchange resin synthesis. The method involves dissolving macroporous or gel polystyrene resin swollen in an inert solvent such as nitrobenzene, using cyclic carbamate as an alkylating agent, and a Lewis acid or ionic liquid as a catalyst, to perform an amine alkylation reaction, yielding a polystyrene resin with primary amine groups and long spacer arms. This resin is then reacted with formic acid and formaldehyde to obtain a tertiary amination polystyrene resin, which is further reacted with bromoethane to obtain a strong base anion exchange resin with long spacer arms. This invention discloses a method for preparing a strong base anion exchange resin with long spacer arms, which simplifies the operation by directly introducing primary amine groups through amine alkylation of white beads, resulting in a simpler process, lower costs, and broad application prospects.

[0005] Strongly basic anion exchange resins have wide applications in water treatment, the power industry, the separation and purification of biological and chemical products, and catalytic synthesis. However, due to their poor thermal stability, their operating temperature is typically limited to no more than 60°C. This limitation stems from the direct bonding of quaternary ammonium groups in the resin to carbon atoms, leading to an increase in the positive charge of the carbon atoms, which in turn reduces thermal stability and restricts their application range. Summary of the Invention

[0006] In view of the above-mentioned deficiencies of the prior art, the technical problem to be solved by the present invention is to provide a styrene-based macroporous strong base anion resin and its preparation method.

[0007] Strongly basic anion exchange resins have a large number of quaternary ammonium exchange groups fixed by chemical bonds. When these resins are placed in water, they can completely dissociate, exhibiting strong basicity. However, under certain heating conditions, some of the strongly basic groups in the resin may transform into weaker basic groups, and some may even detach, leading to a simultaneous decrease in both the exchange capacity and basicity of the ion exchange resin. In the preparation of styrene-based macroporous strongly basic anion exchange resins, crosslinking with piperidine rings linked by alkyl chains in the backbone enhances its stability at high temperatures. After crosslinking, it can resist the degradation of quaternary ammonium groups under nucleophilic substitution and Hoffmann elimination, thereby enhancing its thermal and chemical stability. The relatively stable six-membered heterocycle of piperidine itself also remains relatively stable at high temperatures, and the lone pair electrons on the nitrogen atom can act as ligands to form complexes with metal ions. Therefore, the provided styrene-based macroporous strongly basic anion exchange resin also has a better ability to adsorb metal ions.

[0008] To achieve the above objectives, the present invention provides a method for preparing a styrene-based macroporous strong base anion exchange resin, comprising the following steps:

[0009] S1. Feeding: Add the anhydrous ferric chloride catalyst into the preparation vessel, and send the prepared ferric chloride solution to the chloromethylation vessel.

[0010] S2, Chloromethylation: Styrene-based white spheres are added to the chloromethylation reactor. Chloromethyl ether is pumped into the chloromethylation reactor and allowed to stand for 1 hour. Chlorosulfonic acid is added dropwise to the reactor. After the addition is complete, the temperature is raised and then kept at that temperature. After the reaction, the temperature is lowered to 25°C by cooling water.

[0011] S3. Filtration: Transfer the material in the chloromethylation reactor to the water washing reactor, and filter and separate the chlorine balls and chlorination mother liquor;

[0012] S4. Methanol wash: Add methanol to the water washing tank and wash 3 times.

[0013] S5. Water washing: Rinse the chlorine balls with water three times after washing with methanol.

[0014] S6. Crosslinking and Amination Reaction: A 30wt% dichloromethane solution of 1,5-dipiperidinylpentane from the raw material tank area is pumped into the high-level tank, with the amount being 0.5 to 1 times the mass of the white balls. It is then added dropwise into the reaction vessel, heated to 50 to 65°C, and stirred for 20 to 30 hours. Then, a 30wt% trimethylamine aqueous solution is pumped into the high-level tank and added dropwise into the amination reaction vessel. After the addition is completed, the temperature is raised and kept at the temperature to allow the chlorospheres to undergo an amination reaction, generating a styrene-based macroporous strong base anion resin.

[0015] S7. Distillation: After the amination reaction is completed, the material is sent to a washing kettle, heated to 80°C, and the trimethylamine is condensed and recovered for reuse.

[0016] S8. Adjust pH: After distillation, add 30wt% hydrochloric acid to adjust the pH to neutral.

[0017] S9. Washing and filtration: Add water to the washing tank and wash 3 times. Filter after each washing.

[0018] S10. Packaging: The macroporous strong base anion resin obtained from water washing enters the packaging process and is packaged and stored in a packaging machine.

[0019] Furthermore, the mass ratio of the styrene-based white spheres, chloromethyl ether, anhydrous ferric chloride, and chlorosulfonic acid is 80~88:135~160:1~2:1.

[0020] Furthermore, the dropping temperature in step S2 is 20~30℃.

[0021] Furthermore, the temperature range for heating in step S2 is 40~45℃.

[0022] Furthermore, the heat preservation time in step S2 is 8~12 hours.

[0023] Furthermore, the amount of the trimethylamine aqueous solution used is 1 to 3 times the mass of the white spheres.

[0024] Furthermore, the dropping temperature in step S6 is 20~28℃.

[0025] Furthermore, the temperature range for heating in step S6 is 30~35℃.

[0026] Furthermore, the heat preservation time in step S6 is 6~14h.

[0027] Preferably, the preparation method of the styrene-based macroporous strong base anion exchange resin includes the following steps:

[0028] S1. Feeding: Add the anhydrous ferric chloride catalyst into the preparation vessel, and send the prepared ferric chloride solution to the chloromethylation vessel.

[0029] S2, Chloromethylation: Styrene-based white spheres are added to the chloromethylation reactor. Chloromethyl ether is pumped into the chloromethylation reactor and allowed to stand for 1 hour. Chlorosulfonic acid is then added dropwise to the reactor. The mass ratio of styrene-based white spheres, chloromethyl ether, anhydrous ferric chloride, and chlorosulfonic acid is 80~88:135~160:1~2:1. The dropwise temperature is 20~30℃. After the dropwise addition is complete, the temperature is raised to 40~45℃ and kept at that temperature for 8~12 hours. After the reaction, the temperature is lowered to 25℃ by cooling water.

[0030] S3. Filtration: Transfer the material in the chloromethylation reactor to the water washing reactor, and filter and separate the chlorine balls and chlorination mother liquor;

[0031] S4. Methanol wash: Add methanol to the water washing tank and wash 3 times.

[0032] S5. Water washing: Rinse the chlorine balls with water three times after washing with methanol.

[0033] S6. Crosslinking and Amination Reaction: A 30wt% dichloromethane solution of 1,5-dipiperidinylpentane from the raw material tank area is pumped into the high-level tank, with the amount being 0.5 to 1 times the mass of the white balls. It is then added dropwise into the reaction vessel, and the temperature is raised to 50 to 65°C and stirred for 20 to 30 hours. Then, a 30wt% trimethylamine aqueous solution is pumped into the high-level tank, with the amount of trimethylamine aqueous solution being 1 to 3 times the mass of the white balls. It is then added dropwise into the amination reaction vessel at a temperature of 20 to 28°C. After the addition is completed, the temperature is raised to 30 to 35°C and held for 6 to 14 hours to induce the amination reaction of the chlorospheres, generating a styrene-based macroporous strong base anion resin.

[0034] S7. Distillation: After the amination reaction is completed, the material is sent to a washing kettle, heated to 80°C, and the trimethylamine is condensed and recovered for reuse.

[0035] S8. Adjust pH: After distillation, add 30wt% hydrochloric acid to adjust the pH to neutral.

[0036] S9. Washing and filtration: Add water to the washing tank and wash 3 times. Filter after each washing.

[0037] S10. Packaging: The macroporous strong base anion resin obtained from water washing enters the packaging process and is packaged and stored in a packaging machine.

[0038] The present invention also provides a styrene-based macroporous strong base anion resin, which is prepared by the above method.

[0039] The beneficial effects of this invention are:

[0040] The anion exchange resin in this invention is obtained by chloromethylating styrene-based white spheres to obtain chloromethylated resin, and then crosslinking it by introducing piperidine rings linked by alkyl chains into its backbone. It is then amination with trimethylamine to obtain styrene-based macroporous strong base anion resin. The obtained styrene-based macroporous strong base resin has better high-temperature stability and good adsorption capacity for nitrates and heavy metals. Detailed Implementation

[0041] 1,5-Dipiperidinopentan, CAS No.: 24362-44-5.

[0042] 1-(piperidin-1-yl)piperidine, CAS No.: 6130-94-5. Example 1

[0043] A method for preparing a styrene-based macroporous strong base anion exchange resin includes the following steps:

[0044] S1. Feeding: Add the anhydrous ferric chloride catalyst into the preparation vessel, and send the prepared ferric chloride solution to the chloromethylation vessel.

[0045] S2, Chloromethylation: Styrene-based white spheres are added to the chloromethylation reactor. Chloromethyl ether is pumped into the chloromethylation reactor and allowed to stand for 1 hour. Chlorosulfonic acid is then added dropwise to the reactor. The feed masses of styrene-based white spheres, chloromethyl ether, anhydrous ferric chloride, and chlorosulfonic acid are 0.86 kg, 1.52 kg, 14 g, and 10 g, respectively. The dropwise addition temperature is 25°C. After the dropwise addition is completed, the temperature is raised to 42°C and kept at that temperature for 10 hours. After the reaction, the temperature is lowered to 25°C using cooling water.

[0046] S3. Filtration: Transfer the material in the chloromethylation reactor to the water washing reactor, and filter and separate the chlorine balls and chlorination mother liquor;

[0047] S4. Methanol wash: Add methanol to the water washing tank and wash 3 times.

[0048] S5. Water washing: Rinse the chlorine balls with water three times after washing with methanol.

[0049] S6. Crosslinking and Amination Reaction: A 30wt% dichloromethane solution of 1,5-dipiperidinylpentane from the raw material tank area is pumped into the high-level tank at a dosage of 0.43 kg. The solution is then added dropwise into the reaction vessel, and the temperature is raised to 65°C and stirred for 24 hours. Then, a 30wt% trimethylamine aqueous solution is pumped into the high-level tank at a dosage of 1.72 kg. The solution is then added dropwise into the amination reaction vessel at a dropping temperature of 25°C. After the dropping is completed, the temperature is raised to 30°C and held for 10 hours to induce an amination reaction, producing a styrene-based macroporous strong base anion resin.

[0050] S7. Distillation: After the amination reaction is completed, the material is sent to a washing kettle, heated to 80°C, and the trimethylamine is condensed and recovered for reuse.

[0051] S8. Adjust pH: After distillation, add 30wt% hydrochloric acid to adjust the pH to neutral.

[0052] S9. Washing and filtration: Add water to the washing tank and wash 3 times. Filter after each washing.

[0053] S10. Packaging: The macroporous strong base anion resin obtained from water washing enters the packaging process and is packaged and stored in a packaging machine.

[0054] Compare with Example 1

[0055] The method is basically the same as in Example 1, except that the 30wt% dichloromethane solution of 1,5-dipiperidinylpentane is replaced with an aqueous solution of 30wt% 1,5-diaminopentane, and the amount used is 0.86 kg.

[0056] Compare with Example 2

[0057] The method is basically the same as in Example 1, except that the 30wt% dichloromethane solution of 1,5-dipiperidinylpentane is replaced with an aqueous solution of 30wt% 1,6-hexanediamine, and the amount used is 0.86 kg.

[0058] Compare with Example 3

[0059] The method is basically the same as in Example 1, except that the 30wt% dichloromethane solution of 1,5-dipiperidinylpentane is replaced with a 30wt% dichloromethane solution of 1-(piperidin-1-yl)piperidine, and the amount used is 1.29 kg.

[0060] Compare with Example 4

[0061] The process is basically the same as in Example 1, except that in step S6, a 30wt% solution of 1,5-dipiperidinylpentane in dichloromethane was not added for heating, maintaining the temperature and stirring.

[0062] Test Example 1

[0063] The styrene-based macroporous strong-base anion resins prepared in the examples and control examples were boiled in water for 300 hours, and their strong-base exchange capacity before and after boiling was measured, and the decrease in strong-base exchange capacity was calculated. The styrene-based macroporous strong-base anion resins were subjected to acid and alkali resistance tests. The test method was as follows: 0.5 g of sample was immersed in 25 ml of 5 mol / L hydrochloric acid, deionized water, and 5 mol / L sodium hydroxide solution for 24 hours. After immersion, the sample was washed repeatedly with deionized water, thoroughly dried, and weighed to calculate the mass loss.

[0064] Table 1 Thermal stability test of styrene-based macroporous strong base anion exchange resins

[0065] Strongly basic anion exchange resins have a large number of quaternary ammonium exchange groups fixed by chemical bonds. When these resins are placed in water, they can completely dissociate, exhibiting strong basicity. However, under certain heating conditions, some of the strong basic groups of the resin may be converted into weaker basic groups, and some may even detach, leading to a simultaneous decrease in both the exchange capacity and basicity of the ion exchange resin. Therefore, the strong basic exchange capacity of the resin decreases after boiling water treatment. Compared with Comparative Examples 1-4, Example 1 has a lower loss rate, which may be due to the introduction of piperidine rings linked by alkyl chains into its backbone for crosslinking, thereby improving its stability at high temperatures. After crosslinking, it can resist the degradation of quaternary ammonium groups under nucleophilic substitution and Hoffmann elimination, thus enhancing its thermal stability. The relatively stable six-membered heterocycle of piperidine itself also remains relatively stable at high temperatures. In contrast, the alkylamines used for crosslinking in Comparative Examples 1-2 and the trimethylamine in Comparative Example 4 do not have six-membered heterocycles, and the six-membered heterocycle in Comparative Example 3 lacks alkyl chain phase spacing, which is not conducive to microphase separation and thus affects its chemical stability. Therefore, Example 1 exhibits the best stability.

[0066] Test Example 2

[0067] The adsorption performance of the styrene-based macroporous strong base anion exchange resins prepared in the examples and control examples was tested, and the adsorption of nitrates and Cr was investigated. 6+ Static adsorption experiments were conducted to measure nitrate and Cr levels before and after treatment. 6+ The concentration.

[0068] Table 2 Adsorption Tests of Styrene-based Macroporous Strong Base Anion Resins

[0069]

[0070] Styrene-based macroporous strong-base anion exchange resins can remove nitrates from water. These resins contain strongly basic groups that dissociate into OH groups in water. ⁻Nitrate ions, being strongly alkaline, can be adsorbed and exchanged with anions in solution. In water treatment, strong-base anion exchange resins can absorb nitrate ions through the OH groups on their functional groups. ⁻ The ion exchange resin exchanges nitrate ions with nitrate ions in the solution, thereby removing nitrates from the water. Driven by the exchange potential or concentration difference, the ion exchange resin, through the combined action of physical adsorption and charge neutralization, allows the exchangeable active groups on the exchanger to exchange with chromium ions in the solution, thus achieving the removal purpose. Adsorption tests show that the styrene-based macroporous strong base anion resin prepared in this invention has good removal effects on nitrates and chromium ions. Compared with other control examples, Example 1 shows more outstanding performance in removing chromium ions. This may be due to the introduction of piperidine rings linked by alkyl chains into its backbone for cross-linking. The lone pair electrons on the nitrogen atoms of the piperidine ring can act as ligands to form complexes with chromium ions. Therefore, the styrene-based macroporous strong base anion resin provided in Example 1 has a better ability to adsorb chromium ions.

[0071] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A method for preparing a styrene-based macroporous strong base anionic resin, characterized in that: The steps include: S1. Feeding: Add the catalyst anhydrous ferric chloride into the preparation kettle, and send the prepared ferric chloride solution to the chloromethylation kettle; S2, chloromethylation: add styrene white balls to the chloromethylation reactor, pump the raw material chloromethyl ether into the chloromethylation reactor, let it stand for 1 hour, and drop chlorosulfonic acid into the reactor. The weight of styrene white balls, chloromethyl ether, anhydrous ferric chloride and chlorosulfonic acid are 0.86kg, 1.52kg, 14g and 10g respectively. The dropping temperature is 25°C. After the dropping is completed, the temperature is raised to 42°C and then kept warm for 10 hours. After the reaction, the temperature is cooled to 25°C by cooling water; S3, filtration: transfer the materials in the chloromethylation reaction kettle to the water washing kettle, and filter and separate the chlorine balls and the chlorination mother liquor; S4, methanol washing: add methanol to the washing kettle for washing 3 times; S5, water washing: the chlorine balls washed with methanol are then washed with water for 3 times; S6, cross-linking and amination reaction: 30wt% 1-(piperidin-1-yl)piperidine dichloromethane solution in the raw material tank area is pumped into the header tank, the dosage is 1.29kg, and it is added dropwise into the reactor, heated to 65°C and stirred for 24h, then 30wt% trimethylamine aqueous solution is pumped into the header tank, the dosage of trimethylamine aqueous solution is 1.72kg, and it is added dropwise into the amination reactor, the dropping temperature is 25°C, after the dropwise addition is completed, the temperature is raised to 30°C and kept for 10h, the chlorine ball undergoes amination reaction, and a styrene-based macroporous strong base anionic resin is generated; S7, distillation: after the amination reaction is completed, the material is sent to a washing kettle, the temperature is raised to 80°C, and the trimethylamine is condensed and recovered for reuse; S8, adjusting pH: after the distillation is completed, add 30wt% hydrochloric acid to adjust the pH to neutral; S9, washing and filtering: add water to the washing kettle and wash 3 times, filtering after each washing; S10, Packaging: The macroporous strong alkaline anionic resin obtained by water washing enters the packaging process and is packaged in a packaging device and put into storage.

2. A styrene-based macroporous strong base anionic resin, characterized in that: Prepared by the method described in claim 1.

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