High-purity isopropanol purification method based on modified resin

Abstract

The invention relates to a high-purity isopropanol purification method based on modified resin, which comprises the following steps: adding activated carbon into an isopropanol mixed solution, decolorizing the isopropanol mixed solution, carrying out primary impurity adsorption, and removing particulate matters and macromolecular impurities meeting activated carbon adsorption conditions in the isopropanol mixed solution. The method comprises the following steps: carrying out primary dehydration through a 4A molecular sieve, adding hydrogen-type strong-acid cation exchange resin and hydrogen-oxygen type strong-base anion exchange resin into an isopropanol mixed solution, and removing positive ions and negative ions in the isopropanol mixed solution; the macroporous alkalescence anion exchange resin of the styrene-divinylbenzene copolymer is added, so that the content of residual acid and alkali is lower than 10ppb. The ionic liquid is fixed on hydrogen type strong-acid cation exchange resin and hydrogen-oxygen type strong-base anion exchange resin, and alcohol, ketone and organic acid impurities are removed. And carrying out fractional rectification on the isopropanol mixed solution, and removing light and heavy components to obtain isopropanol with the purity not lower than 99.999%.

Description

Technical Field

[0001] The invention belongs to the technical field of compound purification, and more specifically relates to a high-purity purification method of isopropanol based on modified resin. Background Art

[0002] Ultra-high purity isopropyl alcohol (IPA) is an indispensable and important chemical material in the production process of very large-scale integrated circuits (VLSI), and is widely used in multiple key process links such as lithography, cleaning, and deionization. Due to its versatility and irreplaceability in the production process, the quality of ultra-high purity isopropyl alcohol directly affects the production yield and performance of chips. However, the impurity content of high-purity chemical reagents currently produced generally remains at the level of 100ppb, which is far lower than the ultra-high purity standard required for 8-inch and above semiconductor manufacturing. Therefore, the demand for this high-purity isopropyl alcohol has greatly promoted the urgency of developing higher purity isopropyl alcohol.

[0003] In the purification process of high-purity isopropanol, traditional purification methods mainly rely on technologies such as multi-stage distillation, adsorption and ion exchange resins. However, these methods have some obvious limitations in dealing with organic impurities and organic acid impurities in isopropanol, namely, insufficient adsorption selectivity: traditional cation exchange resins and anion exchange resins show low selectivity in removing specific organic impurities and organic acids. This is because the surface functional groups of these resins are usually fixed, making it difficult to effectively adsorb impurities with large differences in chemical properties. In addition, traditional resins are easily saturated when dealing with complex multi-component mixtures, resulting in a decrease in adsorption effect. Traditional resin treatment also has the problem of adsorption capacity neutralization: when ionic liquids are fixed on exchange resins, the anions or cations of the ionic liquids will bind to the active sites of the resin, thereby neutralizing the original adsorption capacity of the resin. However, the result is that the resins after fixing the ionic liquids show poor adsorption effects when removing impurities, especially under different pH and temperature conditions, the adsorption performance of the resin is difficult to optimize. Summary of the invention

[0004] In order to solve the deficiencies in the prior art, the purpose of the present invention is to solve the above-mentioned defects and further propose a high-purity purification method of isopropanol based on modified resin.

[0005] The present invention adopts the following technical solution.

[0006] The present invention discloses a method for purifying isopropanol with high purity based on modified resin, the method comprising: Step 1, adding activated carbon to an isopropanol mixed solution, decolorizing the isopropanol mixed solution and performing preliminary impurity adsorption on the isopropanol mixed solution, and removing particulate matter in the isopropanol mixed solution and macromolecular impurities that meet the adsorption conditions of the activated carbon; Step 2, performing preliminary dehydration by 4A molecular sieve to reduce the water content in the isopropanol mixed solution to below 300 ppm; Step 3, using a hydrogen-type strongly acidic cation exchange resin to remove cations in the isopropanol mixed solution; Step 4, using a hydroxide-type strong basic anion exchange resin to remove anions in the isopropanol mixed solution, and combining with a macroporous weak basic anion exchange resin of styrene-divinylbenzene copolymer to further remove residual acid and alkali in the isopropanol mixed solution until the residual alkali content is less than 10 ppb; Step 5, fixing the ionic liquid containing chloroaluminate or trifluoromethanesulfonate on a hydrogen-type strongly acidic cation exchange resin to further adsorb alcohol impurities in the isopropanol mixed solution; Step 6, fixing the ionic liquid containing carbonate or sulfate on the hydroxide type strong basic anion exchange resin to further adsorb the organic acid impurities in the isopropanol mixed solution; Step 7, introducing temperature-responsive functional groups and pH-responsive functional groups into the hydrogen-type strongly acidic cation exchange resin and the hydroxide-type strongly basic anion exchange resin to modify the hydrogen-type strongly acidic cation exchange resin and the hydroxide-type strongly basic anion exchange resin to obtain modified resins; Step 9, adsorbing impurities on the isopropyl alcohol mixed solution by the modified resin, and performing graded distillation on the isopropyl alcohol mixed solution by a multi-stage distillation tower to remove light and heavy components in the isopropyl alcohol mixed solution to obtain isopropyl alcohol with a purity of not less than 99.999%; Wherein, the temperature responsive functional group includes N-isopropyl acrylamide monomer, the chemical formula of which is C6H 11 NO, the pH responsive functional group includes a carboxyl functional group and an amino functional group.

[0007] Furthermore, step 1 includes: Step 11, performing ion exchange through anion and cation exchange columns, and preliminarily filtering the isopropanol mixed solution through a high-precision filter element to remove suspended particles and impurities in the isopropanol mixed solution.

[0008] Furthermore, the method further comprises: Step S1, fixing the ionic liquid on the hydrogen-type strongly acidic cation exchange resin and the hydroxide-type strongly basic anion exchange resin by covalent bonding, introducing active groups on the resin surface, and using an epoxy compound as a linker, so that the cations and anions in the ionic liquid are covalently bonded to the surface of the hydrogen-type strongly acidic cation exchange resin and the hydroxide-type strongly basic anion exchange resin through chemical reaction; Wherein, the active groups include amino groups and carboxyl groups.

[0009] Furthermore, step 5 includes: Step 51, covalently bond an ionic liquid containing chloroaluminate or trifluoromethanesulfonate and an ionic liquid containing tetrafluoroborate or bistrifluoromethylsulfonimide to the hydrogen-type strongly acidic cation exchange resin by covalent bonding to adsorb alcohol impurities and ketone impurities in the isopropanol mixed solution.

[0010] Furthermore, step 6 includes: Step 61, covalently bond the ionic liquid containing carbonate or sulfate to the hydroxide type strong basic anion exchange resin by covalent bonding to adsorb the organic acid impurities in the isopropanol mixed solution.

[0011] Furthermore, step 7 includes: Step 71, introducing N-isopropylacrylamide monomer, whose chemical formula is C6H 11 NO, so that the hydrogen-type strongly acidic cation exchange resin and the hydroxide-type strongly basic anion exchange resin selectively adsorb the target molecule by adjusting the temperature; Step 72, introducing a cross-linking agent into the hydrogen-type strongly acidic cation exchange resin and the hydroxide-type strongly basic anion exchange resin to form a cross-linking network on the surface of the hydrogen-type strongly acidic cation exchange resin and the hydroxide-type strongly basic anion exchange resin; Wherein, the cross-linking agent includes N,N'-methylenebisacrylamide, the chemical formula of which is C7H 10 N2O2.

[0012] Further, step 71 includes: Step 711, acid-washing and deionized water-rinsing the hydrogen-type strongly acidic cation exchange resin to remove impurities on the surface of the hydrogen-type strongly acidic cation exchange resin and increase the number of active sites on the surface of the hydrogen-type strongly acidic cation exchange resin; Step 712, under nitrogen conditions, dissolving the isopropyl alcohol mixed solution in the ethanol solution of the N-isopropyl acrylamide monomer, adding the N,N'-methylenebisacrylamide, and maintaining the concentration of the N-isopropyl acrylamide monomer in the solution at 5-10wt%; Step 713, adding a polymerization initiator to allow the N-isopropylacrylamide monomer to undergo a graft polymerization reaction on the surface of the hydrogen-type strongly acidic cation exchange resin; The polymerization initiator includes ammonium persulfate, the chemical formula of which is (NH4)2S2O8, and tetraethylethylenediamine, the chemical formula of which is C6H 16 N2.

[0013] Furthermore, step 713 includes: Step 714, washing the hydrogen-type strongly acidic cation exchange resin after the graft polymerization reaction with deionized water to remove monomers that have not participated in the reaction and byproducts after the reaction on the hydrogen-type strongly acidic cation exchange resin; Step 715, drying the rinsed hydrogen-type strongly acidic cation exchange resin to obtain a hydrogen-type strongly acidic cation exchange resin having temperature responsiveness.

[0014] Furthermore, step 7 also includes: Step 716, introducing a carboxyl functional group or an amino functional group into the hydrogen-type strongly acidic cation exchange resin and the hydroxide-type strongly basic anion exchange resin, so that the hydrogen-type strongly acidic cation exchange resin and the hydroxide-type strongly basic anion exchange resin adjust the ionization state according to the pH change to change the adsorption capacity; Step 717, immersing the hydroxide-type strong basic anion exchange resin in a sodium hydroxide solution, and introducing ethylenediamine to the surface of the hydroxide-type strong basic anion exchange resin to activate the surface of the hydroxide-type strong basic anion exchange resin and remove surface impurities; Step 718, dissolving acrylic acid in water to prepare an acrylic acid solution, and adding ammonium persulfate as an initiator to the acrylic acid solution, so that the acrylic acid is evenly grafted onto the surface of the hydroxide-type strong basic anion exchange resin; Wherein, the ethylenediamine is used to introduce the amino functional group on the surface of the resin, and the acrylic acid is used to introduce the carboxyl functional group on the surface of the resin.

[0015] Furthermore, step 718 includes: Step 719, rinse the hydroxide-type strong basic anion exchange resin with acrylic acid grafted on the surface with deionized water to remove the acrylic acid and initiator remaining on the surface of the hydroxide-type strong basic anion exchange resin, and dry the hydroxide-type strong basic anion exchange resin to obtain a hydroxide-type strong basic anion exchange resin with pH responsiveness.

[0016] The beneficial effects of the present invention are that, compared with the prior art, the present invention has the following advantages: This method uses ionic liquid as a functional material through chemical modification, which significantly improves the ability to remove organic impurities and organic acid impurities in isopropanol. This modification process gives the resin a higher selective adsorption property, allowing it to show a relatively excellent purification effect under complex chemical conditions. In addition, this method also overcomes the problem of neutralization of the adsorption capacity of traditional resins by fixing the ionic liquid on the exchange resin, greatly improving the adaptability of the resin in a changing industrial environment, ensuring that it can efficiently remove impurities under different operating conditions, and improving the overall purification effect of isopropanol. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 The present invention is a schematic flow chart of a method for high-purity purification of isopropanol based on modified resin. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] Combine the following Figure 1 The invention discloses a method for purifying isopropanol with high purity based on modified resin. Example 1

[0021] This example provides a high-purity purification method for isopropanol based on modified resin, combined with Figure 1 As shown, the following steps are included: Step 1: Add activated carbon to the isopropanol mixture to decolorize and preliminarily adsorb impurities on the isopropanol mixture, thereby removing particulate matter and macromolecular impurities that meet the adsorption conditions of the activated carbon in the isopropanol mixture.

[0022] Step 2: Perform preliminary dehydration through 4A molecular sieve to reduce the water content in the isopropanol mixed solution to below 300 ppm.

[0023] In the present invention, the initial isopropanol raw material is usually industrial grade isopropanol (generally with a purity of 99%). In some embodiments, the high-purity purification method of isopropanol based on modified resin provided by the present invention, ionic liquid is added to the isopropanol mixture, ion exchange is performed through an anion and cation exchange column, the flow rate is set in the range of 1-5 mL / min to ensure sufficient contact time, and the amount of ionic liquid added is generally 0.5~2wt% of the mass of the isopropanol mixture. The isopropanol mixture is then preliminarily filtered through a high-precision filter element to remove suspended particles and impurities in the isopropanol mixture. At the same time, activated carbon can also be added to the isopropanol mixture to decolorize the isopropanol mixture and preliminarily adsorb impurities, and further remove particulate matter in the isopropanol mixture and macromolecular impurities that meet the activated carbon adsorption conditions. The high-precision filter element can be selected from a polytetrafluoroethylene (PTFE) filter element or a stainless steel filter element, and the filter pore size is usually between 0.2μm and 0.45μm to effectively remove suspended particles and fine impurities in the mixture.

[0024] Step 3, using hydrogen-type strongly acidic cation exchange resin to remove cations in the isopropanol mixed solution.

[0025] Step 4: using a strong alkaline anion exchange resin of the hydroxide type to remove anions in the isopropanol mixed solution, and combining with a macroporous weak alkaline anion exchange resin of styrene-divinylbenzene copolymer to further remove residual acid and alkali in the isopropanol mixed solution until the residual alkali content is less than 10 ppb.

[0026] Step 5, fixing the ionic liquid containing chloroaluminate or trifluoromethanesulfonate on the hydrogen-type strongly acidic cation exchange resin to further adsorb alcohol impurities in the isopropanol mixed solution.

[0027] Step 6, fixing the ionic liquid containing carbonate or sulfate on the hydroxide type strong basic anion exchange resin to further adsorb the organic acid impurities in the isopropanol mixed solution.

[0028] Step 7, introducing temperature responsive functional groups and pH responsive functional groups into the hydrogen-type strongly acidic cation exchange resin and the hydroxide-type strongly basic anion exchange resin to modify the hydrogen-type strongly acidic cation exchange resin and the hydroxide-type strongly basic anion exchange resin to obtain modified resins.

[0029] The temperature-responsive functional group includes N-isopropylacrylamide monomer, with the chemical formula C6H 11 NO, pH responsive functional groups include carboxyl functional groups and amino functional groups.

[0030] Step 9, adsorbing impurities on the isopropyl alcohol mixed solution by means of a modified resin, and fractionating and rectifying the isopropyl alcohol mixed solution by means of a multi-stage rectification tower to remove light and heavy components in the isopropyl alcohol mixed solution, thereby obtaining isopropyl alcohol having a purity of not less than 99.999%.

[0031] It should be noted that the purity of ultra-high purity isopropyl alcohol used in semiconductor manufacturing, especially in very large scale integrated circuit (VLSI) production, is usually required to reach 99.999% (i.e. 5N purity) or higher.

[0032] Among them, the metal impurity content: single-phase metal impurities are usually required to be less than 1 ppb to avoid adverse effects on sensitive electronic devices during the production process.

[0033] Moisture content: The moisture content is generally required to be less than 10 ppm, while some demanding processes may require lower moisture content.

[0034] Organic impurities: The total amount of organic impurities needs to be controlled below 30 ppb to ensure that no contamination is introduced during processes such as cleaning and photolithography.

[0035] Comparative Example 1: Compared with Example 1, the difference is that the repeated steps are removed, and the other steps are the same as Example 1. Step 1 includes: Step 11, performing ion exchange through anion and cation exchange columns, and preliminarily filtering the isopropanol mixture through a high-precision filter element to remove suspended particles and impurities in the isopropanol mixture.

[0036] Comparative Example 2: Compared with Example 1, the difference is that the repeated steps are removed, and the other steps are the same as Example 1, and the following steps are also included: Step S1, fix the ionic liquid on the hydrogen-type strong acid cation exchange resin and the hydroxide-type strong base anion exchange resin by covalent bonding, introduce active groups on the resin surface, and use epoxy compounds as linkers, so that the cations and anions in the ionic liquid are covalently bonded to the surface of the hydrogen-type strong acid cation exchange resin and the hydroxide-type strong base anion exchange resin through chemical reactions.

[0037] Among them, the active groups include amino and carboxyl groups.

[0038] Comparative Example 3: Compared with Example 1 and Comparative Example 2, the difference is that the repeated steps are removed, and the other steps are the same as those of Example 1 and Comparative Example 2, and Step 5 includes: Step 51, covalently bond the ionic liquid containing chloroaluminate or trifluoromethanesulfonate and the ionic liquid containing tetrafluoroborate or bistrifluoromethylsulfonimide to the hydrogen-type strongly acidic cation exchange resin to adsorb alcohol impurities and ketone impurities in the isopropanol mixed solution.

[0039] Comparative Example 4: Compared with Example 1, Comparative Example 2 and Comparative Example 3, the difference is that the repeated steps are removed, and the other steps are the same as Example 1, Comparative Example 2 and Comparative Example 3, and step 6 includes: Step 61, covalently bond the ionic liquid containing carbonate or sulfate to the hydroxide type strong basic anion exchange resin to adsorb the organic acid impurities in the isopropanol mixed solution.

[0040] Comparative Example 5: Compared with Example 1, the difference is that: the duplicate removal step is the same as Example 1, and step 7 includes: Step 71, introducing N-isopropylacrylamide monomer, whose chemical formula is C6H 11 NO, by adjusting the temperature, the hydrogen-type strongly acidic cation exchange resin and the hydroxide-type strongly basic anion exchange resin can selectively adsorb the target molecule.

[0041] Step 72, introducing a cross-linking agent into the hydrogen-type strongly acidic cation exchange resin and the hydroxide-type strongly basic anion exchange resin to form a cross-linking network on the surface of the hydrogen-type strongly acidic cation exchange resin and the hydroxide-type strongly basic anion exchange resin.

[0042] Among them, the cross-linking agent includes N,N'-methylenebisacrylamide, the chemical formula of which is C7H 10 N2O2.

[0043] Comparative Example 6: Compared with Example 1 and Comparative Example 5, the difference is that the repeated steps are removed, and the other steps are the same as those of Example 1 and Comparative Example 5. Step 71 includes: Step 712, acid-washing and deionized water-rinsing the hydrogen-type strong acid cation exchange resin to remove impurities on the surface of the hydrogen-type strong acid cation exchange resin and increase the number of active sites on the surface of the hydrogen-type strong acid cation exchange resin.

[0044] Step 713, under nitrogen conditions, dissolve the isopropanol mixed solution in the ethanol solution of N-isopropylacrylamide monomer, add N,N'-methylenebisacrylamide, and maintain the concentration of N-isopropylacrylamide monomer in the solution at 5-10 wt%.

[0045] Step 714 , adding a polymerization initiator to cause the N-isopropylacrylamide monomer to undergo a graft polymerization reaction on the surface of the hydrogen-type strongly acidic cation exchange resin.

[0046] The polymerization initiator includes ammonium persulfate, the chemical formula of which is (NH4)2S2O8, and tetraethylethylenediamine, the chemical formula of which is C6H 16 N2.

[0047] Specifically, active groups can be introduced on the surface of the carrier, that is, hydroxyl or amino active groups can be introduced on the surface of the hydrogen-type strongly acidic cation exchange resin, and the free radical reaction activity of the surface can be enhanced by chemical modification to provide reaction sites for the grafting of NIPAAM monomer (N-isopropylacrylamide monomer).

[0048] Introduction of hydroxyl groups: The hydrogen-type strongly acidic cation exchange resin is first treated with hydrogen peroxide (H2O2) to introduce peroxy groups on its surface, and then thermally decomposed at 100°C to generate hydroxyl groups.

[0049] Introduction of amino groups: The surface of hydrogen-type strongly acidic cation exchange resin is treated with ammonia water to react with the activated hydrogen-type strongly acidic cation exchange resin to introduce amino active sites.

[0050] It should be noted that the NIPAAM monomer can adjust its hydrophilicity and hydrophobicity according to temperature changes during the isopropanol purification process. This property enables the ion exchange resin to adsorb water and other polar impurities at low temperatures, and release these impurities at high temperatures, thereby optimizing the purification efficiency. In addition, the phase change properties of the NIPAAM monomer enhance the resin's selective adsorption capacity for different impurities, which helps to achieve high-purity extraction of isopropanol. The NIPAAM monomer is mainly used to remove alcohol impurities from isopropanol. Alcohol impurities often have a certain surface tension, especially in photolithography, which will affect the spreading of the chip wafer surface and the accuracy of the image pattern formation.

[0051] Comparative Example 7: Compared with Example 1, Comparative Example 5 and Comparative Example 6, the difference is that: the repeated steps are removed, and the other steps are the same as Example 1, Comparative Example 5 and Comparative Example 6, and the steps after step 713 include: Step 714 , washing the hydrogen-type strongly acidic cation exchange resin after the graft polymerization reaction with deionized water to remove monomers that have not participated in the reaction and byproducts after the reaction on the hydrogen-type strongly acidic cation exchange resin.

[0052] Step 715, drying the rinsed hydrogen-type strongly acidic cation exchange resin to obtain a hydrogen-type strongly acidic cation exchange resin having temperature responsiveness.

[0053] Comparative Example 8: Compared with Example 1, Comparative Example 5, Comparative Example 6 and Comparative Example 7, the difference is that: the repeated steps are removed, and the other steps are the same as Example 1, Comparative Example 5, Comparative Example 6 and Comparative Example 7, and step 7 further includes: Step 716, introduce carboxyl functional groups or amino functional groups into the hydrogen-type strongly acidic cation exchange resin and the hydroxide-type strongly basic anion exchange resin, so that the hydrogen-type strongly acidic cation exchange resin and the hydroxide-type strongly basic anion exchange resin adjust the ionization state according to the pH change to change the adsorption capacity.

[0054] Step 717, immersing the hydroxide-type strong basic anion exchange resin in a sodium hydroxide solution, and introducing ethylenediamine onto the surface of the hydroxide-type strong basic anion exchange resin to activate the surface of the hydroxide-type strong basic anion exchange resin and remove surface impurities.

[0055] Specifically, it first needs to be epoxidized, that is, the hydroxide-type strong basic anion exchange resin is first treated into an epoxidized resin, for example, using epichlorohydrin (C3H5ClO) to react with the hydroxide-type strong basic anion exchange resin under alkaline conditions to convert the ionic groups on its surface into epoxy groups. Then ethylenediamine grafting is performed, and ethylenediamine (C2H8N2) is reacted with the surface of the epoxidized resin under mild conditions to generate a resin surface with amino functional groups. The reaction process is: epoxy group + ethylenediamine → amine grafted resin.

[0056] It should be noted that after the introduction of ethylenediamine groups, positively charged ammonium ions can be formed on the resin surface, which improves the adsorption capacity of anionic impurities (such as organic acids). This is particularly important for the purification of isopropanol, because many impurities have anionic characteristics, and the introduction of ethylenediamine enhances the resin's ability to remove these impurities, thereby improving the purity and quality of isopropanol. In some embodiments, the concentration of ethylenediamine is typically 5wt%. The introduction of ethylenediamine increases the removal of anionic impurities, especially organic acids (such as formic acid and acetic acid), which can corrode the surface of the wafer and affect the conductivity of the circuit.

[0057] Step 718, dissolving acrylic acid in water to prepare an acrylic acid solution, and adding ammonium persulfate as an initiator to the acrylic acid solution, so that the acrylic acid is evenly grafted onto the surface of the hydroxide-type strong alkaline anion exchange resin.

[0058] Among them, ethylenediamine is used to introduce amino functional groups on the resin surface, and acrylic acid is used to introduce carboxyl functional groups on the resin surface.

[0059] It should be noted that the grafting of acrylic acid enables the resin surface to have carboxyl functional groups, which are negatively charged under alkaline conditions and can effectively adsorb cationic impurities. In this way, the resin can be optimized for both anionic and cationic impurities to improve the overall efficiency of the isopropanol purification process. This dual function enhances the adaptability of the resin under different pH conditions, thereby improving the purification effect of isopropanol. In some embodiments, the concentration of acrylic acid is generally 8wt%. The main function of acrylic acid grafting is to remove cationic impurities in isopropanol.

[0060] Comparative Example 9: Compared with Example 1 and Comparative Examples 5 to 8, the difference is that: the repeated steps are removed, and the other steps are the same as Example 1 and Comparative Examples 5 to 8, and the steps after step 718 include: Step 719, rinse the hydroxide-type strong basic anion exchange resin with acrylic acid grafted on the surface with deionized water to remove the acrylic acid and initiator remaining on the surface of the hydroxide-type strong basic anion exchange resin, and dry the hydroxide-type strong basic anion exchange resin to obtain a hydroxide-type strong basic anion exchange resin with pH responsiveness.

[0061] Finally, the isopropanol mixed solution is preliminarily dehydrated by molecular sieves to ensure that the water content in the isopropanol mixed solution does not exceed 7 ppm. Example 2

[0062] This example provides a high-purity purification method for isopropanol based on modified resin, including steps 1 to 4.

[0063] Step 1, pretreatment process.

[0064] In the pretreatment process, ion exchange is performed through cation and anion exchange columns, and high-precision filter elements are used for preliminary filtration to remove suspended particles and most impurities in the isopropanol mixture to protect subsequent separation and adsorption equipment. In addition, an appropriate amount of activated carbon can be added for decolorization and preliminary impurity adsorption to further purify isopropanol and other processes.

[0065] Among them, the pretreatment process is used to remove most of the particulate matter and large molecular impurities, reducing the purification load of subsequent steps.

[0066] Step 2, dehydration process.

[0067] The dehydration process includes: molecular sieve dehydration, that is, preliminary dehydration through 4A molecular sieve to reduce the moisture content to below 300ppm.

[0068] Step 3: deep impurity removal process.

[0069] In the process of deep impurity removal, hydrogen-type strong acid cation exchange resin is first used to remove cations in isopropanol, such as sodium, potassium, calcium, iron, etc. Hydroxy-type strong base anion exchange resin is used to remove anions, and combined with macroporous weak base anion exchange resin of styrene-divinylbenzene copolymer, the residual acid and alkali are further removed to less than 10 ppb.

[0070] Secondly, an ionic liquid containing chloroaluminate or trifluoromethanesulfonate is fixed on a cation exchange resin to further adsorb alcohol impurities. At the same time, an ionic liquid containing tetrafluoroborate or bistrifluoromethanesulfonimide is fixed on a cation exchange resin to further adsorb ketone impurities. In addition, an ionic liquid containing carbonate or sulfate is fixed on an anion exchange resin to further adsorb organic acid impurities.

[0071] Among them, the deep impurity removal process is used to remove metal ions, organic impurities, organic acid impurities, etc., and can further remove moisture to ensure that the ultra-high purity requirements of isopropyl alcohol are met.

[0072] In this embodiment, the ionic liquid can be fixed on the cation exchange resin or the anion exchange resin by covalent bonding. In the covalent bonding process, firstly, active groups (such as amino groups or carboxyl groups) are introduced on the surface of the resin, and then epoxy compounds are used as linkers, so that the cations or anions of the ionic liquid are covalently bonded to the surface of the anion exchange resin or the cation exchange resin through chemical reactions. This method can ensure that the ionic liquid is firmly attached to the resin surface and prevent it from being eluted during use.

[0073] It should be noted that fixing the ionic liquid on the exchange resin essentially neutralizes the adsorption capacity of the surface of the anion exchange resin or cation exchange resin.

[0074] In this embodiment, the resin needs to be chemically modified so that it exhibits higher selectivity under specific conditions (such as different pH values ​​and different temperature conditions), including steps A1 to A2.

[0075] Step A1, introducing temperature-responsive functional groups.

[0076] Principle: The temperature-responsive functional group changes its chemical and physical properties by adjusting the temperature, thereby achieving selective adsorption of specific target molecules. Among them, commonly used temperature-responsive materials include N-isopropylacrylamide (NIPAAM) monomer (chemical formula C6H 11 NO).

[0077] The crosslinking agent is N,N'-methylenebisacrylamide (MBAA), with the chemical formula of C7H 10N2O2 is used to form a stable cross-linking network on the resin surface to enhance the stability of the temperature-responsive polymer.

[0078] Specifically, step A1 includes the following steps: Step A11, resin surface pretreatment: A cation exchange resin is selected as the substrate, and impurities on the resin surface are removed by acid washing and deionized water washing to increase the number of surface active sites.

[0079] Step A12, NIPAAM grafting: Under nitrogen protection, isopropanol was dissolved in an ethanol solution of N-isopropylacrylamide (NIPAAM) monomer to ensure the stability of the polymer, and then an appropriate amount of crosslinker N,N'-methylenebisacrylamide (MBAA) was added to maintain the concentration of NIPAAM in the solution at 5-10 wt%. Subsequently, polymerization initiators such as ammonium persulfate (APS, chemical formula (NH4)2S2O8) and tetraethylethylenediamine (TEMED, chemical formula C6H 16 N2) to promote the grafting polymerization of NIPAAM on the resin surface. During the grafting polymerization process, the reaction temperature was controlled at 25°C and the stirring time was 4 hours to ensure uniform grafting of NIPAAM. The NIPAAM monomer concentration was controlled at 5-10 wt% to avoid the problem of excessively long polymer chains and uneven grafting due to high concentration.

[0080] The mass of the cross-linking agent is 1-2wt% of the mass of NIPAAM to ensure the formation of a stable cross-linked network; the monomer mass of ammonium persulfate can be set to 0.2wt%, and the molar ratio of tetraethylethylenediamine to ammonium persulfate is 1:1; and the temperature is controlled to be room temperature, and the stirring rate is 200-300rpm.

[0081] In addition, it is necessary to introduce active groups on the surface of the carrier and hydroxyl or amino active groups on the surface of the ion exchange resin to enhance the free radical reaction activity of the surface through chemical modification to provide reaction sites for the grafting of NIPAAM monomers.

[0082] It should be noted that compared with other temperature-responsive monomers (such as NEAM, NPAM, etc.), NIPAAM not only has better compatibility with isopropanol and does not introduce new impurities; at the same time, the phase transition of NIPAAM is sharp and reversible, which is conducive to improving the adsorption and desorption efficiency.

[0083] Introduction of hydroxyl groups: The resin is first treated with hydrogen peroxide (H2O2) to introduce peroxy groups on the surface, and then thermally decomposed at 100°C to generate hydroxyl groups.

[0084] Introduction of amino groups: Use ammonia water to treat the resin surface and react with the activated resin to introduce amino active sites.

[0085] In this embodiment, the NIPAAM monomer can adjust its hydrophilicity and hydrophobicity according to temperature changes during the isopropanol purification process. This property enables the resin to adsorb water and other polar impurities at low temperatures, and release these impurities at high temperatures, optimizing the purification efficiency. In addition, the phase change property of the NIPAAM monomer enhances the resin's selective adsorption capacity for different impurities, which helps to achieve high-purity extraction of isopropanol.

[0086] In general technology, activated carbon adsorption, pervaporation membrane separation and other methods can also be used. However, compared with the use of NIPAAM monomer in the present invention, these methods have higher impurity residues and are difficult to meet high purity requirements. Table 1 shows the measurement results of different treatment methods for removing alcohol impurities.

[0087] Table 1

[0088] Treatment Initial content (ppm) Content after treatment (ppm) NIPAAM monomer grafting 100 2 Activated carbon adsorption method 100 19 Pervaporation membrane separation 100 15 Among them, the above methods all use high performance liquid chromatography (HPLC) to determine the content of alcohol impurities in isopropanol.

[0089] Step A13, post-processing: After the graft polymerization reaction is completed, the resin is rinsed with deionized water to remove unreacted monomers and by-products, and then the treated resin is dried at 50°C to obtain a functionalized resin with temperature responsiveness.

[0090] Step A2, introducing pH responsive functional groups.

[0091] Principle: pH-responsive functional groups can adjust their ionization state according to the pH changes of the environment, thereby changing the adsorption capacity of the resin. Commonly used pH-responsive functional groups include carboxyl (-COOH) and amino (-NH2).

[0092] The materials for introducing pH-responsive functional groups are selected as follows: Acrylic acid (chemical formula: C3H4O2) is used to introduce carboxyl functional groups on the resin surface. The carboxyl groups are deprotonated under alkaline conditions and behave as negatively charged carboxylates, which can improve the adsorption capacity of cationic impurities on the resin.

[0093] Ethylene diamine (chemical formula: C2H8N2) is used to introduce amino functional groups on the resin surface. The amino groups are protonated under acidic conditions and behave as positively charged ammonium ions, which can improve the adsorption capacity of anionic impurities.

[0094] Specifically, step A2 includes the following steps: Step A21, resin surface activation: Anion exchange resin was selected as the substrate, ethylenediamine was introduced on the surface of the anion exchange resin, and the resin was immersed in a 0.1M sodium hydroxide solution to remove impurities on the surface of the resin and activate it.

[0095] The specific steps of introducing ethylenediamine groups on the surface are: (1) It needs to undergo epoxidation treatment first: the hydroxide-type strong alkaline anion exchange resin is first treated into an epoxidized resin, for example, using epichlorohydrin (C3H5ClO) to react with the resin under alkaline conditions to convert part of the surface ionic groups into epoxy groups.

[0096] (2) Ethylenediamine grafting: Ethylenediamine (C2H8N2) (using ethylenediamine solution with a concentration of 5-10wt%) is reacted with the epoxidized resin surface under mild conditions to generate a resin surface with amine functional groups. The reaction process is: epoxy + ethylenediamine → amine grafted resin. The reaction time is 2-4h. Ensure that the reaction is carried out under a nitrogen atmosphere, and keep the temperature at 50-100°C and the pH value at 6.5.

[0097] In this embodiment, after the introduction of ethylenediamine groups, positively charged ammonium ions can be formed on the resin surface. At the same time, ethylenediamine has two primary amine groups, providing two active sites, which can effectively react with active groups (such as epoxy groups) on the resin to form stable covalent bonds, thereby improving the adsorption capacity for anionic impurities (such as organic acids). This is particularly important for the purification of isopropanol, because many impurities have anionic characteristics, and the introduction of ethylenediamine enhances the resin's ability to remove these impurities, thereby improving the purity and quality of isopropanol.

[0098] Table 2 shows the measured results of the removal of anionic impurities by different treatment methods.

[0099] Table 2

[0100] Treatment Initial content (ppm) Content after treatment (ppm) Introduction of ethylenediamine groups 100 0.2 Unmodified strong base anion exchange resin method 100 7 Among them, the above methods all use ion chromatography (IC) to determine the content of anionic impurities in isopropanol.

[0101] Step A22, acrylic acid grafting: Acrylic acid was dissolved in water to prepare a 10% acrylic acid solution, and then ammonium persulfate (APS) was added as an initiator. The solution was stirred at 60°C for 3 hours to evenly graft the acrylic acid onto the resin surface.

[0102] In this embodiment, the grafting of acrylic acid enables the resin surface to have carboxyl functional groups, which are negatively charged under alkaline conditions and can effectively adsorb cationic impurities. In this way, the resin can be optimized for both anionic and cationic impurities, thereby improving the overall efficiency of the isopropanol purification process. This dual function enhances the adaptability of the resin under different pH conditions, thereby improving the purification effect of isopropanol.

[0103] Step A23, post-processing: After acrylic acid was uniformly grafted onto the resin surface, the resin was repeatedly rinsed with deionized water to remove residual acrylic acid and initiator, and then dried at 70°C to form a functionalized resin with pH responsiveness.

[0104] How pH-responsive functionalized resins work: Under acidic conditions, the carboxyl groups (-COOH) on the resin surface are protonated and uncharged, reducing the adsorption of cations, but the amino groups (-NH2) are protonated into ammonium ions (-NH3⁺), enhancing the adsorption of anions.

[0105] It should be noted that, through the above-mentioned change in charge state, the resin can achieve selective adsorption of different types of impurities under different pH conditions. For example, under acidic conditions, the resin can more effectively adsorb anionic impurities, while under alkaline conditions, the resin has a stronger adsorption capacity for cations.

[0106] In this embodiment, the reaction device and process parameters are as follows: Reaction apparatus: A reactor, which is equipped with a stirring and temperature control system and is used to carry out polymerization and grafting reactions under uniform temperature and stirring conditions.

[0107] Temperature control system: used to accurately control the reaction temperature in the reactor, especially in the preparation of temperature-responsive resins, the reaction temperature needs to be strictly controlled at 25-60°C.

[0108] pH control device: In the preparation of pH responsive resin, the pH value of the reaction solution is adjusted by a pH control device to ensure the smooth progress of the reaction.

[0109] In this embodiment, the process parameters are as follows: Reaction time: In the preparation of temperature-responsive resins, the grafting reaction time of NIPAAM is 4-6 hours. In the preparation of pH-responsive resins, the grafting reaction time of acrylic acid or ethylenediamine is 2-3 hours.

[0110] Temperature range: NIPAAM grafting reaction temperature is 25-30°C, acrylic acid grafting reaction temperature is 60-70°C, subsequent drying treatment temperature is 50-70°C, and NIPAAM monomer concentration is controlled at 5-10 wt% to avoid problems such as excessive polymer chain length and uneven grafting caused by high concentration.

[0111] pH range: During the introduction of pH-responsive functional groups, the pH value was kept at neutral to weak peroxy alkalinity (pH 7-8) during acrylic acid grafting and at weak acidity (pH 5-6) during amino grafting.

[0112] Step 4, distillation nanofiltration process.

[0113] In the distillation and nanofiltration process, the isopropanol mixed liquid is graded and distilled by a multi-stage distillation tower, the tower top temperature is controlled at 82±0.5℃, and the reflux ratio is controlled between 1.5-2. The graded distillation can effectively remove the light and heavy components in the isopropanol, and finally obtain high-purity isopropanol. In addition, a highly selective nanofiltration membrane is used, the pressure is controlled at 0.5-1.0 MPa, and the flow rate is controlled at 50-150 L / h to remove trace impurities and reduce the ion content.

[0114] Among them, the distillation nanofiltration process is used to further purify isopropyl alcohol and remove light and heavy components therein to ensure that the purified isopropyl alcohol can reach the required purity, while further removing trace impurities to ensure the ultra-high purity of isopropyl alcohol.

[0115] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0116] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A high-purity purification method for isopropanol based on modified resin, characterized in that: The method comprises: Step 1, adding activated carbon to an isopropanol mixed solution, decolorizing the isopropanol mixed solution and performing preliminary impurity adsorption on the isopropanol mixed solution, and removing particulate matter in the isopropanol mixed solution and macromolecular impurities that meet the adsorption conditions of the activated carbon; Step 2, performing preliminary dehydration through 4A molecular sieve to reduce the water content in the isopropanol mixed solution to below 300 ppm; Step 3, using a hydrogen-type strongly acidic cation exchange resin to remove cations in the isopropanol mixed solution; Step 4, using a hydroxide-type strong basic anion exchange resin to remove anions in the isopropanol mixed solution, and combining with a macroporous weak basic anion exchange resin of styrene-divinylbenzene copolymer to further remove residual acid and alkali in the isopropanol mixed solution until the residual alkali content is less than 10 ppb; Step 5, fixing the ionic liquid containing chloroaluminate or trifluoromethanesulfonate on a hydrogen-type strongly acidic cation exchange resin to further adsorb alcohol impurities in the isopropanol mixed solution; Step 6, fixing the ionic liquid containing carbonate or sulfate on the hydroxide type strong basic anion exchange resin to further adsorb the organic acid impurities in the isopropanol mixed solution; Step 7, introducing temperature-responsive functional groups and pH-responsive functional groups into the hydrogen-type strongly acidic cation exchange resin and the hydroxide-type strongly basic anion exchange resin to modify the hydrogen-type strongly acidic cation exchange resin and the hydroxide-type strongly basic anion exchange resin to obtain modified resins; Step 9, adsorbing impurities on the isopropyl alcohol mixed solution by the modified resin, and performing graded distillation on the isopropyl alcohol mixed solution by a multi-stage distillation tower to remove light and heavy components in the isopropyl alcohol mixed solution to obtain isopropyl alcohol with a purity of not less than 99.999%; Wherein, the temperature responsive functional group includes N-isopropyl acrylamide monomer, the chemical formula of which is C6H 11 NO, the pH responsive functional group includes a carboxyl functional group and an amino functional group.

2. The method for high-purity purification of isopropanol based on modified resin according to claim 1, characterized in that: Step 1 includes: Step 11, performing ion exchange through anion and cation exchange columns, and preliminarily filtering the isopropanol mixed solution through a high-precision filter element to remove suspended particles and impurities in the isopropanol mixed solution.

3. The method for high-purity purification of isopropanol based on modified resin according to claim 1, characterized in that: The method further comprises: Step S1, fixing the ionic liquid on the hydrogen-type strongly acidic cation exchange resin and the hydroxide-type strongly basic anion exchange resin by covalent bonding, introducing active groups on the resin surface, and using an epoxy compound as a linker, so that the cations and anions in the ionic liquid are covalently bonded to the surface of the hydrogen-type strongly acidic cation exchange resin and the hydroxide-type strongly basic anion exchange resin through chemical reaction; Wherein, the active groups include amino groups and carboxyl groups.

4. The method for high-purity purification of isopropanol based on modified resin according to claim 3, characterized in that: Step 5 includes: Step 51, covalently bond an ionic liquid containing chloroaluminate or trifluoromethanesulfonate and an ionic liquid containing tetrafluoroborate or bistrifluoromethylsulfonimide to the hydrogen-type strongly acidic cation exchange resin by covalent bonding to adsorb alcohol impurities and ketone impurities in the isopropanol mixed solution.

5. The method for high-purity purification of isopropanol based on modified resin according to claim 4, characterized in that: Step 6 includes: Step 61, covalently bond the ionic liquid containing carbonate or sulfate to the hydroxide type strong basic anion exchange resin by covalent bonding to adsorb the organic acid impurities in the isopropanol mixed solution.

6. The method for high-purity purification of isopropanol based on modified resin according to claim 1, characterized in that: Step 7 includes: Step 71, introducing N-isopropylacrylamide monomer, whose chemical formula is C6H 11 NO, so that the hydrogen-type strongly acidic cation exchange resin and the hydroxide-type strongly basic anion exchange resin selectively adsorb the target molecule by adjusting the temperature; Step 72, introducing a cross-linking agent into the hydrogen-type strongly acidic cation exchange resin and the hydroxide-type strongly basic anion exchange resin to form a cross-linking network on the surface of the hydrogen-type strongly acidic cation exchange resin and the hydroxide-type strongly basic anion exchange resin; Wherein, the cross-linking agent includes N,N'-methylenebisacrylamide, the chemical formula of which is C7H 10 N2O2.

7. The method for high-purity purification of isopropanol based on modified resin according to claim 6, characterized in that: Step 71 includes: Step 711, acid-washing and deionized water-rinsing the hydrogen-type strongly acidic cation exchange resin to remove impurities on the surface of the hydrogen-type strongly acidic cation exchange resin and increase the number of active sites on the surface of the hydrogen-type strongly acidic cation exchange resin; Step 712, under nitrogen conditions, dissolving the isopropyl alcohol mixed solution in the ethanol solution of the N-isopropyl acrylamide monomer, adding the N,N'-methylenebisacrylamide, and maintaining the concentration of the N-isopropyl acrylamide monomer in the solution at 5-10wt%; Step 713, adding a polymerization initiator to allow the N-isopropylacrylamide monomer to undergo a graft polymerization reaction on the surface of the hydrogen-type strongly acidic cation exchange resin; The polymerization initiator includes ammonium persulfate, the chemical formula of which is (NH4)2S2O8, and tetraethylethylenediamine, the chemical formula of which is C6H 16 N2.

8. The method for high-purity purification of isopropanol based on modified resin according to claim 7, characterized in that: Step 713 includes: Step 714, washing the hydrogen-type strongly acidic cation exchange resin after the graft polymerization reaction with deionized water to remove monomers that have not participated in the reaction and byproducts after the reaction on the hydrogen-type strongly acidic cation exchange resin; Step 715, drying the rinsed hydrogen-type strongly acidic cation exchange resin to obtain a hydrogen-type strongly acidic cation exchange resin having temperature responsiveness.

9. The method for high-purity purification of isopropanol based on modified resin according to claim 8, characterized in that: Step 7 also includes: Step 716, introducing a carboxyl functional group or an amino functional group into the hydrogen-type strongly acidic cation exchange resin and the hydroxide-type strongly basic anion exchange resin, so that the hydrogen-type strongly acidic cation exchange resin and the hydroxide-type strongly basic anion exchange resin adjust the ionization state according to the pH change to change the adsorption capacity; Step 717, immersing the hydroxide-type strong basic anion exchange resin in a sodium hydroxide solution, and introducing ethylenediamine to the surface of the hydroxide-type strong basic anion exchange resin to activate the surface of the hydroxide-type strong basic anion exchange resin and remove surface impurities; Step 718, dissolving acrylic acid in water to prepare an acrylic acid solution, and adding ammonium persulfate as an initiator to the acrylic acid solution, so that the acrylic acid is evenly grafted onto the surface of the hydroxide-type strong basic anion exchange resin; Wherein, the ethylenediamine is used to introduce the amino functional group on the surface of the resin, and the acrylic acid is used to introduce the carboxyl functional group on the surface of the resin.

10. The method for purifying isopropanol with high purity based on modified resin according to claim 9, characterized in that: Step 718 then includes: Step 719, rinse the hydroxide-type strong basic anion exchange resin with acrylic acid grafted on the surface with deionized water to remove the acrylic acid and initiator remaining on the surface of the hydroxide-type strong basic anion exchange resin, and dry the hydroxide-type strong basic anion exchange resin to obtain a hydroxide-type strong basic anion exchange resin with pH responsiveness.

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