A high-purity isopropyl alcohol adsorption dehydration and impurity stripping refining method for semiconductor cleaning

Abstract

The application discloses a high-purity isopropyl alcohol adsorption dehydration and impurity stripping refining method for semiconductor cleaning, and belongs to the field of alcohol compound separation and purification, which comprises the following steps: feeding the isopropyl alcohol to be refined into a pre-dehydration section to obtain pre-dehydrated isopropyl alcohol with a body phase water content of not higher than 500 ppm; and feeding the pre-dehydrated isopropyl alcohol into a limited water activity stripping section, wherein the limited water activity stripping section is filled with a limited water activity adsorbent; the cooperation of the pre-dehydration section, the limited water activity stripping section and the terminal dehydration polishing section enables the borate ester impurities and the complex metal impurities to be stripped and fixed under the condition that the water content of the isopropyl alcohol main liquid phase is controlled, and the problems that the difficult-to-strip impurities cannot be removed by conventional dehydration and the product water content is unstable due to the body phase water treatment are solved, so that the effects of low water content control and trace impurity removal are achieved.

Description

Technical Field

[0001] This invention relates to the field of alcohol separation and purification technology, and more specifically, to a method for high-purity isopropanol adsorption dehydration and impurity stripping purification for semiconductor cleaning. Background Technology

[0002] Isopropanol is commonly used for cleaning, drying, and surface treatment of semiconductor wafers. Its content of moisture, boron impurities, metallic impurities, and organic carbonyl impurities affects the cleanliness of the wafer surface and the stability of subsequent processes. Isopropanol used for semiconductor cleaning typically requires dehydration, adsorption, distillation, or filtration to reduce its moisture and trace impurities.

[0003] Existing methods for isopropanol purification often combine molecular sieve dehydration, adsorbent removal, and distillation separation. While these methods are effective at removing free water and some polar organic impurities, their effectiveness is limited in removing borate esters and diacetone alcohol-metal complexes from near-anhydrous isopropanol.

[0004] These impurities are highly mobile in the isopropanol bulk liquid phase and do not easily undergo form transformation in low moisture environments, making it difficult to stably reduce their content through simple dehydration or conventional adsorption.

[0005] If water is directly introduced into the bulk liquid phase of isopropanol to promote the conversion of borate ester impurities or complexed metal impurities, it will significantly increase the subsequent dehydration load, making it difficult to maintain the moisture content of the finished isopropanol within the range required for semiconductor cleaning.

[0006] Therefore, the problem in the prior art is how to promote the stripping or fixation of borate ester impurities and complexed metal impurities while keeping the isopropanol bulk liquid phase at a low moisture content, so as to obtain isopropanol with low moisture content and high purity after subsequent processing. Summary of the Invention

[0007] To address the problems mentioned in the background section, the present invention provides the following technical solution: A method for high-purity isopropanol adsorption dehydration and impurity removal purification for semiconductor cleaning includes the following steps: S1. Pass the isopropanol to be purified into the pre-dehydration section to obtain pre-dehydrated isopropanol with a bulk water content of not more than 500 ppm. S2. Pre-dehydrated isopropanol is introduced into the confined water activity stripping section, which is filled with a confined water activity adsorbent. Confined water activity adsorbents include boron trapping particles and metal trapping particles. Both boron trapping particles and metal trapping particles use mesoporous silica as an inorganic framework. The pore surface of boron trapping particles is covalently grafted with vicinal diol groups, and the pore surface of metal trapping particles is covalently grafted with imine diacetic acid groups. Boron-capturing particles and metal-capturing particles are mixed and placed in a high-purity nitrogen atmosphere for equilibration, allowing trace amounts of water to enter the mesoporous channels and form channel-bound water with hydroxyl, vicinal diol and imine diacetic acid groups on the pore walls. The confined water activity adsorbent has mesoporous channels of 2nm to 10nm. The water filling rate θw of the confined water activity adsorbent is 5% to 45%. The water filling rate θw is the ratio of the volume of bound water Vw in the channel to the total pore volume Vp of the adsorbent. Among them, the mass increase of the adsorbent after drying to constant weight was measured as a reference, and the mass increase was converted into the volume of bound water in the pores Vw according to the density of water. The equilibrium water activity (aw) of the confined water activity adsorbent, measured in a closed system at 25°C, ranged from 0.15 to 0.65. After the pre-dehydrated isopropanol passes through the confined water activity stripping section, the increase in bulk water content ΔW is no more than 100 ppm. When pre-dehydrated isopropanol passes through the confined water activity stripping section, borate ester impurities and complexed metal impurities undergo stripping or coordination transformation at the pore interface of the confined water activity adsorbent, forming interfacial retained impurities. S3. The isopropanol that has been treated by the confined water activity stripping section is passed into the final dehydration and polishing section to reduce the water content of the isopropanol to no more than 10 ppm, thereby obtaining high-purity isopropanol.

[0008] Furthermore, in step S1, the bulk water content of the pre-dehydrated isopropanol is 10 ppm to 500 ppm. In step S2, the increase in bulk water content ΔW after the pre-dehydrated isopropanol passes through the confined water activity stripping section is 5 ppm to 100 ppm. In step S3, the isopropanol moisture content after the final dehydration and polishing section is no higher than 5 ppm.

[0009] Furthermore, the preparation of boron capturing particles includes: grafting 3-glycidyl etheroxypropyltrimethoxysilane onto the surface of mesoporous silica channels, and then allowing the amino group in N-methyl-D-glucamine to undergo a ring-opening reaction with the epoxy group on the surface of the mesoporous channels to obtain boron capturing particles with ortho-diol groups covalently grafted onto the surface of the mesoporous channels. The preparation of metal trapping particles includes: grafting 3-aminopropyltriethoxysilane onto the surface of mesoporous silica channels, followed by carboxylation reaction with sodium chloroacetate to obtain metal trapping particles with imine diacetic acid groups covalently grafted onto the surface of the mesoporous channels. Boron trapping particles and metal trapping particles are mixed at a mass ratio of 7:3.

[0010] Furthermore, the confined water activity stripping section includes an interface conversion zone, an impurity fixation zone, and a water release buffer zone arranged sequentially along the isopropanol flow direction; The equilibrium water activity (aw) in the interface transition zone is 0.35–0.65. The equilibrium water activity (aw) in the impurity fixation zone is 0.20–0.45. The equilibrium water activity (aw) of the water release buffer zone is 0.15–0.30; Isopropanol passes sequentially through the interfacial transformation zone, the impurity fixation zone, and the water release buffer zone, causing boronic acid ester impurities and complexed metal impurities to first undergo interfacial stripping or coordination transformation, and then be fixed by the impurity capturing groups, thereby reducing the amount of pore-bound water released into the isopropanol bulk phase.

[0011] Furthermore, the stripping efficiency value E of the confined water activity stripping section was determined by the reduction ratio of boron, the reduction ratio of metal, and the increase ratio of moisture. The stripping efficiency value E satisfies the following relationship: E=a·ΔB / Bin+b·ΔM / Min-c·ΔW / Wlim; Wherein, ΔB is the decrease in boron content before and after the confined water activity stripping section, Bin is the boron content before entering the confined water activity stripping section, ΔM is the decrease in metal content before and after the confined water activity stripping section, Min is the metal content before entering the confined water activity stripping section, ΔW is the increase in bulk moisture before and after the confined water activity stripping section, and Wlim is the allowable moisture limit before entering the final dehydration and polishing section. 'a' is the boron control coefficient, which ranges from 1.0 to 1.5. b is the metal control coefficient, with a value ranging from 0.8 to 1.2; c is the water release penalty coefficient, which ranges from 0.6 to 1.0; When the stripping efficiency value E is lower than the set efficiency threshold, switch the confined water activity stripping section or regenerate the confined water activity stripping section.

[0012] Furthermore, high-purity isopropanol at a temperature of 20°C is introduced into the confined water activity stripping section to be regenerated at a flow rate of 0.5 BV / h and an injection volume of 3 BV. After the replacement is completed, dry nitrogen gas is introduced into the confined water activity stripping section. The dew point of the dry nitrogen gas is below -60℃, the purging temperature is 50℃, and the purging time is 4 hours. After the drying nitrogen purging is completed, high-purity nitrogen gas at a temperature of 25℃ and a relative humidity of 30% is introduced into the confined water activity stripping section for 3 hours. Then, ultra-dry isopropanol with a water content of 4.5 ppm is introduced into the confined water activity stripping section at a flow rate of 0.4 BV / h until the increase in water content of isopropanol at the adsorption column outlet relative to the inlet isopropanol is less than 30 ppm for three consecutive times.

[0013] In summary, the present invention has the following beneficial effects: This invention, through the combination of a pre-dehydration section, a confined water activity stripping section, and a final dehydration and polishing section, enables borate ester impurities and complexed metal impurities to be stripped and fixed under controlled moisture conditions in the isopropanol bulk liquid phase. This solves the problems of conventional dehydration failing to remove difficult-to-strip impurities and the instability of finished product moisture caused by bulk phase water treatment, thereby achieving the effect of balancing low moisture control and trace impurity removal. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 This is a flowchart illustrating the overall process of the method of the present invention. Figure 2 This is a flowchart illustrating the preparation process of the confined water activity adsorbent of the present invention. Figure 3 This is a schematic diagram of the structure of the partitioned confined water activity stripping section of the present invention; Figure 4 This is a flowchart illustrating the process of determining peeling efficiency, bed switching, and regeneration in this invention. Detailed Implementation

[0016] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] Example 1

[0018] The following is in conjunction with the appendix Figure 1-4 The present invention will be described in further detail below.

[0019] This invention provides a technical solution: a method for high-purity isopropanol adsorption dehydration and impurity removal purification for semiconductor cleaning, comprising the following steps: S1. Pass the isopropanol to be purified into the pre-dehydration section to obtain pre-dehydrated isopropanol with a bulk water content of not more than 500 ppm. S2. Pre-dehydrated isopropanol is introduced into the confined water activity stripping section, which is filled with a confined water activity adsorbent. Confined water activity adsorbents include boron trapping particles and metal trapping particles. Both boron trapping particles and metal trapping particles use mesoporous silica as an inorganic framework. The pore surface of boron trapping particles is covalently grafted with vicinal diol groups, and the pore surface of metal trapping particles is covalently grafted with imine diacetic acid groups. Boron-capturing particles and metal-capturing particles are mixed and placed in a high-purity nitrogen atmosphere for equilibration, allowing trace amounts of water to enter the mesoporous channels and form channel-bound water with hydroxyl, vicinal diol and imine diacetic acid groups on the pore walls. The confined water activity adsorbent has mesoporous channels of 2nm to 10nm. The water filling rate θw of the confined water activity adsorbent is 5% to 45%. The water filling rate θw is the ratio of the volume of bound water Vw in the channel to the total pore volume Vp of the adsorbent. Among them, the mass increase of the adsorbent after drying to constant weight was measured as a reference, and the mass increase was converted into the volume of bound water in the pores Vw according to the density of water. The equilibrium water activity (aw) of the confined water activity adsorbent, measured in a closed system at 25°C, ranged from 0.15 to 0.65. After the pre-dehydrated isopropanol passes through the confined water activity stripping section, the increase in bulk water content ΔW is no more than 100 ppm. When pre-dehydrated isopropanol passes through the confined water activity stripping section, borate ester impurities and complexed metal impurities undergo stripping or coordination transformation at the pore interface of the confined water activity adsorbent, forming interfacial retained impurities. S3. The isopropanol that has been treated by the confined water activity stripping section is passed into the end dehydration and polishing section to reduce the water content of the isopropanol to no more than 10 ppm, so as to obtain high-purity isopropanol. Confined water activity adsorbents include boron trapping particles and metal trapping particles. Both boron trapping particles and metal trapping particles use mesoporous silica as an inorganic framework. The pore surface of boron trapping particles is covalently grafted with vicinal diol groups, and the pore surface of metal trapping particles is covalently grafted with imine diacetic acid groups.

[0020] In this embodiment, a confined water activity adsorbent for the confined water activity stripping section is prepared. Boron capturing particles and metal capturing particles are mixed at a mass ratio of 7:3 and used as filler for the confined water activity stripping section.

[0021] The average pore size is 6.5 nm and the total pore volume is 0.80 cm³. 3 / g of mesoporous silica was used as the inorganic framework of the boron capturing particles. The mesoporous impurity capturing groups, including o-diol silica, were immersed in 0.05mol / L nitric acid solution for 2h, and then washed with 18MΩ·cm ultrapure water until the conductivity of the washing solution was less than 1μS / cm.

[0022] The washed mesoporous silica was dried at 120°C for 6 hours to obtain a pretreated mesoporous silica framework.

[0023] Take 100g of pretreated mesoporous silica and add it to 1000mL of anhydrous toluene. Then add 18mL of 3-glycidyl etheroxypropyltrimethoxysilane and react at 80℃ for 8h under nitrogen protection to covalently graft the epoxy-containing silane coupling agent onto the pore surface of the mesoporous silica.

[0024] After the reaction was completed, the solid product was washed sequentially with anhydrous toluene and high-purity isopropanol to remove unreacted silane coupling agent.

[0025] The washed solid product was added to an isopropanol solution containing N-methyl-D-glucamine and reacted at 65°C for 10 h to allow the amino group in N-methyl-D-glucamine to undergo a ring-opening reaction with the epoxy group on the pore surface, resulting in boron trapping particles with vicinal diol groups covalently grafted onto the pore surface.

[0026] The average pore size was set at 5.8 nm, and the total pore volume at 0.76 cm³. 3 / g of mesoporous silica was used as the inorganic framework for metal trapping particles. The mesoporous silica was immersed in 0.05mol / L nitric acid solution for 2h, and then washed with 18MΩ·cm ultrapure water until the conductivity of the washing solution was less than 1μS / cm.

[0027] The washed mesoporous silica was dried at 120°C for 6 hours to obtain a pretreated inorganic framework of metal-capturing particles.

[0028] Take 100g of pretreated metal capture particle inorganic framework and add it to 1000mL of anhydrous toluene, then add 16mL of 3-aminopropyltriethoxysilane. React at 80℃ for 6h under nitrogen protection to allow aminopropyl to be covalently grafted onto the pore surface of mesoporous silica.

[0029] After the reaction was completed, the solid product was washed with anhydrous toluene and high-purity isopropanol. The solid product was then added to an ethanol-water mixed solution containing sodium chloroacetate. The pH of the system was controlled at 8.5-9.5, and the reaction was carried out at 70°C for 8 hours to induce carboxymethylation of the aminopropyl groups on the pore surface, resulting in metal trapping particles with imine diacetic acid groups covalently grafted onto the pore surface.

[0030] The boron-capturing particles and metal-capturing particles were washed with high-purity isopropanol until the content of Fe, Ni, Cr and Cu in the eluent was less than 5 ppt and the organic residue in the eluent was below the gas chromatography detection limit.

[0031] The washed boron capturing particles and metal capturing particles were purged in dry nitrogen at 50°C for 4 hours to remove residual solvent from the pores, and then mixed at a mass ratio of 7:3 to obtain the composite adsorbent to be conditioned.

[0032] The composite adsorbent to be conditioned was placed in a high-purity nitrogen atmosphere at 25°C and 35% relative humidity for 6 hours to allow trace amounts of water to enter the mesoporous channels and form channel-bound water with hydroxyl groups, vicinal diol groups and imine diacetic acid groups on the pore walls, thus obtaining the initial water conditioning adsorbent.

[0033] Using the composite adsorbent dried to constant weight as a benchmark, the mass increase of the initial water conditioning adsorbent was measured, and the mass increase was converted into the bound water volume Vw in the pores according to the density of water.

[0034] The total pore volume Vp of the initial water conditioning adsorbent was determined by nitrogen adsorption, and the water filling rate θw in the pores was calculated according to θw=Vw / Vp.

[0035] The initial water conditioning adsorbent was measured to have an average pore size of 6.1 nm and a total pore volume of 0.74 cm³. 3 / g, the water filling rate θw in the pore is 18%, and the equilibrium water activity aw measured in closed equilibrium at 25℃ is 0.36.

[0036] The initial water-conditioning adsorbent was loaded into a polytetrafluoroethylene-lined adsorption column, and ultra-dry isopropanol with a water content of 4.5 ppm was introduced for equilibration at a flow rate of 0.5 BV / h until the increase in water content of isopropanol at the adsorption column outlet relative to that at the inlet was less than 30 ppm.

[0037] After equilibration, the pore water filling rate θw and equilibrium water activity aw of the adsorbent were remeasured. The pore water filling rate θw was 16% and the equilibrium water activity aw was 0.33.

[0038] When blank isopropanol with a moisture content of 4.5 ppm was passed through the equilibrated adsorbent, the moisture content of the isopropanol at the outlet was 26.2 ppm, the increase in bulk moisture was 21.7 ppm, and the increase in the content of individual metals Fe, Ni, Cr, and Cu was no more than 2 ppt.

[0039] The confined water activity adsorbent prepared by the above steps has mesoporous channels, channel-bound water, and covalently grafted impurity capturing groups, and is suitable for the interfacial stripping and fixation of borate ester impurities and complexed metal impurities in the subsequent isopropanol purification process.

[0040] Example 2

[0041] like Figure 1-4 As shown, in step S1, the bulk water content of the pre-dehydrated isopropanol is 10 ppm to 500 ppm. In step S2, the increase in bulk water content ΔW after the pre-dehydrated isopropanol passes through the confined water activity stripping section is 5 ppm to 100 ppm. In step S3, the isopropanol moisture content after the final dehydration and polishing section is no higher than 5 ppm.

[0042] 3-glycidyl etheroxypropyltrimethoxysilane was grafted onto the surface of the mesoporous channels of mesoporous silica, and then the amino group in N-methyl-D-glucamine was subjected to a ring-opening reaction with the epoxy group on the surface of the mesoporous channels to obtain boron trapping particles with ortho-diol groups covalently grafted onto the surface of the mesoporous channels. The preparation of metal trapping particles includes: grafting 3-aminopropyltriethoxysilane onto the surface of mesoporous silica channels, followed by carboxylation reaction with sodium chloroacetate to obtain metal trapping particles with imine diacetic acid groups covalently grafted onto the surface of the mesoporous channels. Boron trapping particles and metal trapping particles are mixed at a mass ratio of 7:3.

[0043] In this embodiment, the confined water activity adsorbent prepared in Example 1 is used to adsorb, dehydrate, and remove impurities from the isopropanol to be purified.

[0044] Before refining, high-purity nitrogen with a dew point below -60℃ is used to purge the pre-dehydration section, the confined water activity stripping section, the end dehydration and polishing section, and the connecting pipelines for 2 hours. The liquid contact parts of the pre-dehydration section, the confined water activity stripping section, and the end dehydration and polishing section are made of polytetrafluoroethylene or perfluoroalkoxy materials.

[0045] 1000 kg of isopropanol to be refined was used as raw material. The isopropanol to be refined had a water content of 1260 ppm, a boron content of 86 ppt, an Fe content of 38 ppt, a Ni content of 27 ppt, a Cr content of 31 ppt, a Cu content of 36 ppt, a total Fe, Ni, Cr and Cu metal content of 132 ppt, and a diacetone alcohol content of 420 ppt.

[0046] The isopropanol to be purified is introduced into the pre-dehydration section, which is filled with 3A molecular sieves that have been treated with acid washing, ultrapure water washing and high-purity isopropanol replacement. The bed temperature is controlled at 25℃ and the liquid flow rate is controlled at 1.5 BV / h.

[0047] The first 1 BV of isopropanol after the pre-dehydration section begins to be discharged is collected as a replacement fluid, and the subsequent discharge is used as pre-dehydrated isopropanol to enter the confined water activity stripping section.

[0048] The pre-dehydrated isopropanol contained 82 ppm of water, 84 ppt of boron, 37 ppt of Fe, 26 ppt of Ni, 30 ppt of Cr, 35 ppt of Cu, and a total of 128 ppt of Fe, Ni, Cr, and Cu metals. The diacetone alcohol content was 410 ppb.

[0049] Pre-dehydrated isopropanol was introduced into the confined water activity stripping section, which was filled with the confined water activity adsorbent prepared in Example 1. The water filling rate θw of the confined water activity adsorbent was 16%, the equilibrium water activity aw was 0.33, and the average pore size was 6.1 nm.

[0050] The bed temperature of the confined water activity stripping section is controlled at 25℃, the liquid flow rate is controlled at 0.8 BV / h, and the bed pressure is controlled at 0.10 MPa~0.15 MPa.

[0051] After the pre-dehydrated isopropanol passed through the confined water activity stripping section, the water content of the isopropanol was 119 ppm, and the increase in bulk water content ΔW was 37 ppm.

[0052] Testing revealed that the boron content in the isopropanol at the outlet of the confined water activity stripping section decreased to 18 ppt, the Fe content decreased to 13 ppt, the Ni content decreased to 8 ppt, the Cr content decreased to 9 ppt, the Cu content decreased to 11 ppt, the total amount of Fe, Ni, Cr and Cu metals decreased to 41 ppt, and the diacetone alcohol content decreased to 105 ppt.

[0053] The above test results show that after the pre-dehydrated isopropanol passes through the confined water activity stripping section, the boron content corresponding to borate ester impurities is significantly reduced, the diacetone alcohol content and the total metal content decrease simultaneously, and the increase in bulk water content remains within 100 ppm.

[0054] Isopropanol, after being processed by the confined water activity stripping section, is introduced into the final dehydration and polishing section. The final dehydration and polishing section is filled with 3A molecular sieves that have undergone low-metal washing treatment. The bed temperature is controlled at 25°C and the liquid flow rate is controlled at 1.0 BV / h.

[0055] The first 0.5 BV of isopropanol after the end dehydration and polishing section begins to discharge is collected as a replacement solution, and the subsequent discharge is collected as the finished isopropanol.

[0056] The product's isopropanol contained 4.8 ppm of water, 17 ppt of boron, 12 ppt of Fe, 7 ppt of Ni, 8 ppt of Cr, 11 ppt of Cu, and a total of 38 ppt of Fe, Ni, Cr, and Cu metals. The diacetone alcohol content was 98 pptb.

[0057] To verify the stability of continuous purification, the isopropanol to be purified was continuously processed for 10 hours under the above process conditions, and samples of the water activity stripping section outlet and the finished isopropanol were taken every 2 hours.

[0058] During continuous processing, the bulk water increase ΔW of isopropanol at the outlet of the confined water activity stripping section was maintained at 34ppm to 43ppm, the boron content was maintained at 18ppt to 23ppt, the total metal content of Fe, Ni, Cr and Cu was maintained at 41ppt to 48ppt, and the diacetone alcohol content was maintained at 105ppb to 126ppb.

[0059] During continuous processing, the moisture content of the finished isopropanol is maintained at 4.8ppm to 6.5ppm, the boron content at 17ppt to 22ppt, the total amount of Fe, Ni, Cr and Cu metals at 38ppt to 46ppt, and the diacetone alcohol content at 98ppb to 120ppb.

[0060] The results above show that after the purified isopropanol is pre-dehydrated, it enters a low moisture state in the bulk phase. The confined water activity stripping section reduces borate ester impurities, diacetone alcohol, and metal impurities under the condition that the increase in bulk phase moisture is controlled. The final dehydration and polishing section further reduces the moisture to the low moisture level required for isopropanol used in semiconductor cleaning.

[0061] Example 3

[0062] like Figure 1-4 As shown, the confined water activity stripping section includes an interface conversion zone, an impurity fixation zone, and a water release buffer zone arranged sequentially along the isopropanol flow direction; The equilibrium water activity (aw) in the interface transition zone is 0.35–0.65. The equilibrium water activity (aw) in the impurity fixation zone is 0.20–0.45. The equilibrium water activity (aw) of the water release buffer zone is 0.15–0.30; Isopropanol passes sequentially through the interfacial transformation zone, the impurity fixation zone, and the water release buffer zone, causing boronic acid ester impurities and complexed metal impurities to first undergo interfacial stripping or coordination transformation, and then be fixed by the impurity capturing groups, thereby reducing the amount of pore-bound water released into the isopropanol bulk phase.

[0063] The stripping efficiency value E of the confined water activity stripping section was determined by the reduction ratio of boron, the reduction ratio of metal, and the increase ratio of moisture. The stripping efficiency value E satisfies the following relationship: E=a·ΔB / Bin+b·ΔM / Min-c·ΔW / Wlim; Wherein, ΔB is the decrease in boron content before and after the confined water activity stripping section, Bin is the boron content before entering the confined water activity stripping section, ΔM is the decrease in metal content before and after the confined water activity stripping section, Min is the metal content before entering the confined water activity stripping section, ΔW is the increase in bulk moisture before and after the confined water activity stripping section, and Wlim is the allowable moisture limit before entering the final dehydration and polishing section. 'a' is the boron control coefficient, which ranges from 1.0 to 1.5. b is the metal control coefficient, with a value ranging from 0.8 to 1.2; c is the water release penalty coefficient, which ranges from 0.6 to 1.0; When the stripping efficiency value E is lower than the set efficiency threshold, switch the confined water activity stripping section or regenerate the confined water activity stripping section.

[0064] High-purity isopropanol at 20°C is introduced into the confined water activity stripping section to be regenerated at a flow rate of 0.5 BV / h and an injection volume of 3 BV. After the replacement is completed, dry nitrogen gas is introduced into the confined water activity stripping section. The dew point of the dry nitrogen gas is below -60℃, the purging temperature is 50℃, and the purging time is 4 hours. After the drying nitrogen purging is completed, high-purity nitrogen gas at a temperature of 25℃ and a relative humidity of 30% is introduced into the confined water activity stripping section for 3 hours. Then, ultra-dry isopropanol with a water content of 4.5 ppm is introduced into the confined water activity stripping section at a flow rate of 0.4 BV / h until the increase in water content of isopropanol at the adsorption column outlet relative to the inlet isopropanol is less than 30 ppm for three consecutive times. This embodiment, based on embodiment 2, divides the confined water activity stripping section into zones.

[0065] The confined water activity stripping section is sequentially filled with interfacial conversion zone packing, impurity fixation zone packing and water release buffer packing along the isopropanol flow direction, with a packing volume ratio of 3:4:3.

[0066] The filler in the interface conversion zone is a mixture of boron-capturing particles and metal-capturing particles from Example 1, and the mixture is placed in a high-purity nitrogen atmosphere at 25°C and 45% relative humidity for 5 hours to equilibrate.

[0067] The average pore size of the filler in the interface conversion zone was measured to be 7.4 nm, and the total pore volume was 0.79 cm³. 3 / g, the water filling rate θw in the pores is 28%, and the equilibrium water activity aw is 0.51.

[0068] The impurity fixing zone packing uses a mixture of boron-capturing particles and metal-capturing particles from Example 1, and the mixture is placed in a high-purity nitrogen atmosphere at 25°C and 32% relative humidity for 6 hours for equilibration.

[0069] The average pore size of the packing material in the impurity stationary zone was measured to be 6.0 nm, and the total pore volume was 0.74 cm³. 3 / g, the water filling rate θw in the pores is 17%, and the equilibrium water activity aw is 0.34.

[0070] The water release buffer packing material is the composite adsorbent equilibrated with ultra-dry isopropanol as described in Example 1, and the composite adsorbent is placed in a high-purity nitrogen atmosphere at 25°C and 20% relative humidity for 4 hours for equilibration.

[0071] The average pore size of the packing material in the water release buffer zone was measured to be 4.5 nm, and the total pore volume was 0.68 cm³. 3 / g, the water filling rate θw in the pores is 9%, and the equilibrium water activity aw is 0.22.

[0072] The three types of packing materials were sequentially loaded into a polytetrafluoroethylene-lined adsorption column. During the loading process, high-purity nitrogen with a dew point below -60°C was used for protection. After loading, ultra-dry isopropanol with a water content of 4.8 ppm was used for pre-column equilibration.

[0073] During column pre-equilibration, the flow rate of ultra-dry isopropanol is 0.4 BV / h. Column pre-equilibration is terminated after the increase in water content of isopropanol at the adsorption column outlet relative to the inlet is below 35 ppm for three consecutive times.

[0074] Pre-dehydrated isopropanol was used as feed. The water content of the pre-dehydrated isopropanol was 76 ppm, the boron content was 91 ppt, the Fe content was 41 ppt, the Ni content was 29 ppt, the Cr content was 34 ppt, the Cu content was 41 ppt, the total metal content of Fe, Ni, Cr and Cu was 145 ppt, and the diacetone alcohol content was 460 ppt.

[0075] Pre-dehydrated isopropanol is introduced into the partitioned confined water activity stripping section, with the bed temperature controlled at 25℃, the liquid flow rate controlled at 0.8 BV / h, and the bed pressure controlled at 0.10 MPa~0.15 MPa.

[0076] Pre-dehydrated isopropanol first enters the interfacial transformation zone, where boronic acid ester impurities and complexed metal impurities undergo stripping or coordination transformation in the pore interface with higher equilibrium water activity.

[0077] After being processed in the interface conversion zone, isopropanol enters the impurity fixation zone. The boron centers corresponding to boronic acid ester impurities are fixed by vicinal diol groups, and the metals in diacetone alcohol-metal complex impurities are fixed by imine diacetic acid groups.

[0078] After being treated in the impurity fixation zone, isopropanol enters the water release buffer zone, which reduces the amount of migratable trace water carried out by isopropanol from the first two zones.

[0079] The water content of isopropanol at the outlet of the zoned water activity stripping section is 108 ppm, and the increase in bulk water content ΔW is 32 ppm.

[0080] Testing revealed that the boron content in the isopropanol at the outlet of the zoned water activity stripping section decreased to 15 ppt, the Fe content decreased to 11 ppt, the Ni content decreased to 7 ppt, the Cr content decreased to 8 ppt, the Cu content decreased to 8 ppt, the total amount of Fe, Ni, Cr, and Cu metals decreased to 34 ppt, and the diacetone alcohol content decreased to 88 ppt.

[0081] Isopropanol from the outlet of the partitioned water activity stripping section is introduced into the final dehydration and polishing section. The final dehydration and polishing section is filled with 3A molecular sieves that have undergone low-metal washing treatment. The bed temperature is controlled at 25°C and the liquid flow rate is controlled at 1.0 BV / h.

[0082] After being processed by the end dehydration and polishing section, the finished product has a water content of 4.2 ppm, a boron content of 14 ppt, a total metal content of Fe, Ni, Cr and Cu of 32 ppt, and a diacetone alcohol content of 82 pptb.

[0083] To verify the impact of zoning settings on moisture release, the single-zone confined water activity stripping section in Example 2 was used as a reference under the same feeding conditions.

[0084] After reference treatment, the bulk water content ΔW of isopropanol at the outlet of the confined water activity stripping section was 39 ppm, the boron content was 19 ppt, the total metal content of Fe, Ni, Cr and Cu was 43 ppt, and the diacetone alcohol content was 110 ppt.

[0085] Compared with the reference treatment, in this embodiment, the increase in bulk water content in the partitioned confined water activity stripping section was reduced from 39 ppm to 32 ppm, the boron content was reduced from 19 ppt to 15 ppt, the total amount of Fe, Ni, Cr and Cu metals was reduced from 43 ppt to 34 ppt, and the diacetone alcohol content was reduced from 110 ppt to 88 ppt.

[0086] The above results indicate that setting up an interface conversion zone, an impurity fixation zone, and a water release buffer zone with decreasing equilibrium water activity along the isopropanol flow direction can improve the removal efficiency of borate ester impurities and complexed metal impurities, and reduce the increase in isopropanol bulk phase moisture by the confined water activity stripping section.

[0087] Example 4

[0088] In this embodiment, the boron control coefficient a is 1.2, the metal control coefficient b is 1.0, the water release penalty coefficient c is 0.8, the allowable moisture limit Wlim for entering the final dehydration and polishing section is 100 ppm, and the set efficiency threshold is 0.85.

[0089] Boron control coefficient 'a' is used to increase the influence of boron content changes on the judgment results; metal control coefficient 'b' is used to reflect the influence of total metal changes on the cleanliness of the finished product; and water release penalty coefficient 'c' is used to reflect the load influence on the final dehydration and polishing section after water is released from the confined water activity stripping section.

[0090] During the second hour of continuous operation, the boron content in the isopropanol at the inlet of the confined water activity stripping section was 80 ppt, and the boron content in the isopropanol at the outlet was 16 ppt, with a boron reduction ratio ΔB / Bin of 0.80.

[0091] During the same sampling period, the total amount of Fe, Ni, Cr and Cu metals in the isopropanol at the inlet of the confined water activity stripping section was 120 ppt, and the total amount of Fe, Ni, Cr and Cu metals in the isopropanol at the outlet was 36 ppt, with a metal reduction ratio ΔM / Min of 0.70.

[0092] During the same sampling period, the water content of isopropanol at the inlet of the confined water activity stripping section was 78 ppm, and the water content of isopropanol at the outlet was 108 ppm. The increase in bulk water content ΔW was 30 ppm, and the water content increase ratio ΔW / Wlim was 0.30.

[0093] According to the calculation based on E=a·ΔB / Bin+b·ΔM / Min-c·ΔW / Wlim, we get E=1.2×0.80+1.0×0.70-0.8×0.30=1.42.

[0094] Since E is higher than the set efficiency threshold of 0.85, the confined water activity stripping section continues to be used for isopropanol purification.

[0095] After 8 hours of continuous operation, the boron content in the isopropanol at the inlet of the confined water activity stripping section was 83 ppt, and the boron content in the isopropanol at the outlet was 23 ppt, with a boron reduction ratio ΔB / Bin of 0.72.

[0096] During the same sampling period, the total amount of Fe, Ni, Cr and Cu metals in the isopropanol at the inlet of the confined water activity stripping section was 124 ppt, and the total amount of Fe, Ni, Cr and Cu metals in the isopropanol at the outlet was 45 ppt, with a metal reduction ratio ΔM / Min of 0.64.

[0097] During the same sampling period, the water content of isopropanol at the inlet of the confined water activity stripping section was 81 ppm, and the water content of isopropanol at the outlet was 119 ppm. The increase in bulk water content ΔW was 38 ppm, and the water content increase ratio ΔW / Wlim was 0.38.

[0098] The calculation yields E = 1.2 × 0.72 + 1.0 × 0.64 - 0.8 × 0.38 = 1.20.

[0099] Since E remains above the set efficiency threshold of 0.85, the confined water activity stripping section continues to operate.

[0100] After 16 hours of continuous operation, the boron content in the isopropanol at the inlet of the confined water activity stripping section was 82 ppt, and the boron content in the isopropanol at the outlet was 49 ppt, with a boron reduction ratio ΔB / Bin of 0.40.

[0101] During the same sampling period, the total amount of Fe, Ni, Cr and Cu metals in the isopropanol at the inlet of the confined water activity stripping section was 126 ppt, and the total amount of Fe, Ni, Cr and Cu metals in the isopropanol at the outlet was 88 ppt, with a metal reduction ratio ΔM / Min of 0.30.

[0102] During the same sampling period, the water content of isopropanol at the inlet of the confined water activity stripping section was 83 ppm, and the water content of isopropanol at the outlet was 138 ppm. The increase in bulk water content ΔW was 55 ppm, and the water content increase ratio ΔW / Wlim was 0.55.

[0103] The calculation yields E = 1.2 × 0.40 + 1.0 × 0.30 - 0.8 × 0.55 = 0.34.

[0104] Since E is lower than the set efficiency threshold of 0.85, the isopropanol feed is switched from the current confined water activity stripping section to the standby confined water activity stripping section.

[0105] Before commissioning, the standby water activity stripping section was equilibrated with ultra-dry isopropanol with a moisture content of 4.5 ppm. The moisture content of the isopropanol at the standby bed outlet was 24 ppm compared to that at the inlet.

[0106] After switching to the standby confined water activity stripping section, pre-dehydrated isopropanol was continued to be introduced at a flow rate of 0.8 BV / h, and samples were taken for testing 30 minutes after the switch.

[0107] Testing revealed that the boron content in the isopropanol at the inlet of the standby confined water activity stripping section was 81 ppt, and the boron content in the isopropanol at the outlet was 19 ppt. The total amount of Fe, Ni, Cr, and Cu metals decreased from 122 ppt to 40 ppt, and the increase in bulk moisture was 31 ppm.

[0108] The E value for the spare confined water activity stripping section is 1.35, calculated using the same method.

[0109] The deactivated water activity stripping section is isolated separately, and after draining the residual isopropanol from the bed, it is transferred to the regeneration process.

[0110] This embodiment illustrates that the stripping efficiency value E can be used to determine the decrease in the stripping capacity of the confined water activity stripping section and to determine the timing of bed switching.

[0111] Example 5

[0112] This embodiment regenerates the confined water activity stripping section that was switched off in Embodiment 4.

[0113] In this embodiment, the dew point is used to indicate the water content in nitrogen gas; the lower the dew point, the drier the nitrogen gas.

[0114] In this embodiment, blank isopropanol refers to ultra-dry isopropanol without the addition of borate ester impurities, diacetone alcohol, and metal impurities.

[0115] Before regeneration, the residual isopropanol in the confined water activity stripping section is discharged, and high-purity nitrogen is used to purge for 30 minutes at room temperature.

[0116] A sample of the adsorbent before regeneration was taken for testing. The water filling rate θw in the pores of the adsorbent was 7%, and the equilibrium water activity aw was 0.12.

[0117] When blank isopropanol with a moisture content of 4.5 ppm was passed through the adsorbent bed before regeneration, the moisture content of the outlet isopropanol increased by 58 ppm.

[0118] A standard isopropanol sample containing 80 ppt boron and a total of 120 ppt Fe, Ni, Cr, and Cu metals was passed through the adsorbent bed before regeneration. The outlet boron content was 51 ppt, and the outlet total Fe, Ni, Cr, and Cu metal content was 86 ppt.

[0119] The above test results are used to record the state of the bed before regeneration.

[0120] High-purity isopropanol at 20°C was introduced into the confined water activity stripping section at a flow rate of 0.5 BV / h and an injection volume of 3 BV.

[0121] This step is used to replace residual isopropanol and weakly adsorbed organic impurities in the bed.

[0122] After the replacement is completed, dry nitrogen gas is introduced into the confined water activity stripping section. The nitrogen dew point is below -60℃, the purging temperature is 50℃, and the purging time is 4 hours.

[0123] This step is used to remove excess moisture and volatile impurities from the channels.

[0124] After the drying nitrogen purging is completed, high-purity nitrogen containing trace amounts of water is introduced into the confined water activity stripping section. The nitrogen temperature is 25℃, the relative humidity is 30%, and the treatment time is 3 hours.

[0125] This step is used to allow trace amounts of water to re-enter the mesoporous channels and form channel-bound water with the pore wall hydroxyl groups, vicinal diol groups, and imine diacetic acid groups.

[0126] After the high-purity nitrogen gas treatment containing trace amounts of water is completed, ultra-dry isopropanol with a water content of 4.5 ppm is introduced into the confined water activity stripping section at a flow rate of 0.4 BV / h.

[0127] When the increase in moisture content of isopropanol at the adsorption column outlet relative to that at the inlet is less than 30 ppm for three consecutive times, the ultra-dry isopropanol equilibration is stopped.

[0128] After regeneration, an adsorbent sample was taken for testing. The water filling rate θw in the pores of the adsorbent was 19%, and the equilibrium water activity aw was 0.35.

[0129] When blank isopropanol with a moisture content of 4.5 ppm was passed through the regenerated adsorbent bed, the moisture content of the outlet isopropanol was 27.1 ppm, and the moisture content increase was 22.6 ppm.

[0130] A standard isopropanol sample containing 80 ppt boron and a total of 120 ppt Fe, Ni, Cr, and Cu metals was passed through the regenerated adsorbent bed. The outlet boron content was 21 ppt, and the outlet total Fe, Ni, Cr, and Cu metal content was 44 ppt.

[0131] The regenerated adsorbent bed was reused in the purification process of Example 2. The water content of isopropanol at the inlet of the confined water activity stripping section was 81 ppm, the boron content was 83 ppt, the total metal content of Fe, Ni, Cr and Cu was 126 ppt, and the diacetone alcohol content was 430 ppt.

[0132] After being treated by the regenerated confined water activity stripping section, the water content of the outlet isopropanol is 114 ppm, the increase in bulk water content is 33 ppm, the boron content is reduced to 20 ppt, the total amount of Fe, Ni, Cr and Cu metals is reduced to 43 ppt, and the diacetone alcohol content is reduced to 112 ppb.

[0133] After being processed by the end dehydration and polishing section, the finished product has a water content of 5.3 ppm, a boron content of 19 ppt, a total metal content of Fe, Ni, Cr and Cu of 41 ppt, and a diacetone alcohol content of 108 ppt.

[0134] In this embodiment, after the confined water activity stripping section is replaced with high-purity isopropanol, purged with dry nitrogen, regulated with nitrogen containing trace amounts of water, and balanced with ultra-dry isopropanol, the water filling rate θw and the equilibrium water activity aw in the pores are restored to the target range. The increase in water content after blank isopropanol passes through the bed is less than 30 ppm, and the removal capacity of boron and metal impurities in the standard isopropanol sample is restored.

[0135] Comparative Example 1 This comparative example uses a completely dry adsorbent to treat pre-dehydrated isopropanol.

[0136] The composite adsorbent prepared in Example 1 was placed in dry nitrogen at 120°C for 8 hours and then cooled to 25°C for later use.

[0137] Tests showed that the water filling rate θw of the completely dry adsorbent was less than 2%, and the equilibrium water activity aw measured in closed equilibrium at 25°C was less than 0.05.

[0138] Isopropanol treated in the pre-dehydration stage in Example 2 was used as feed. The feed moisture content was 82 ppm, boron content was 84 ppt, Fe content was 37 ppt, Ni content was 26 ppt, Cr content was 30 ppt, Cu content was 35 ppt, the total amount of Fe, Ni, Cr and Cu metals was 128 ppt, and diacetone alcohol content was 410 ppb.

[0139] Pre-dehydrated isopropanol was introduced into the completely dry adsorbent bed, with the bed temperature controlled at 25°C, the liquid flow rate controlled at 0.8 BV / h, and the bed pressure controlled at 0.10 MPa~0.15 MPa.

[0140] The water content of isopropanol at the outlet of the completely dry adsorbent bed is 85 ppm, and the increase in bulk moisture is 3 ppm.

[0141] Testing revealed that the isopropanol at the outlet of the completely dry adsorbent bed contained 75 ppt of boron, 33 ppt of Fe, 23 ppt of Ni, 27 ppt of Cr, and 30 ppt of Cu. The total amount of Fe, Ni, Cr, and Cu metals was 113 ppt, and the diacetone alcohol content was 366 ppb.

[0142] Isopropanol from the outlet of the completely dry adsorbent bed is introduced into the end dehydration and polishing section. The water content of the isopropanol at the outlet of the end dehydration and polishing section is 4.6 ppm, the boron content is 74 ppt, the total metal content of Fe, Ni, Cr and Cu is 111 ppt, and the diacetone alcohol content is 360 ppb.

[0143] In this comparative example, the completely dry adsorbent resulted in a smaller increase in moisture content in the isopropanol bulk phase, but the decrease in boron content, total metal content, and diacetone alcohol content was relatively small. This indicates that when the adsorbent is in an over-dry state, its ability to exfoliate borate ester impurities and complexed metal impurities is insufficient.

[0144] Comparative Example 2 This comparative example uses the method of adding free water to the isopropanol bulk phase to treat pre-dehydrated isopropanol.

[0145] Isopropanol treated in the pre-dehydration stage in Example 2 was used as feed. The feed moisture content was 82 ppm, boron content was 84 ppt, Fe content was 37 ppt, Ni content was 26 ppt, Cr content was 30 ppt, Cu content was 35 ppt, the total amount of Fe, Ni, Cr and Cu metals was 128 ppt, and diacetone alcohol content was 410 ppb.

[0146] Add ultrapure water to the pre-dehydrated isopropanol and stir for 30 min to increase the bulk water content of the isopropanol to 350 ppm.

[0147] Isopropanol with added water was introduced into the impurity capturing adsorbent bed. The impurity capturing adsorbent used was the composite adsorbent treated with dried nitrogen in Example 1. The bed temperature was controlled at 25°C, the liquid flow rate was controlled at 0.8 BV / h, and the bed pressure was controlled at 0.10 MPa~0.15 MPa.

[0148] The water content of isopropanol at the outlet of the impurity capture adsorbent bed was 332 ppm.

[0149] Testing revealed that the isopropanol at the outlet of the impurity capture adsorbent bed contained 20 ppt of boron, 14 ppt of Fe, 9 ppt of Ni, 10 ppt of Cr, and 12 ppt of Cu, with a total metal content of 45 ppt for Fe, Ni, Cr, and Cu, and a diacetone alcohol content of 118 ppb.

[0150] Isopropanol from the outlet of the impurity capturing adsorbent bed is introduced into the end dehydration and polishing section, which is filled with 3A molecular sieves that have undergone low-metal washing treatment. The bed temperature is controlled at 25°C and the liquid flow rate is controlled at 1.0 BV / h.

[0151] In the first hour after the start of finished product collection, the water content of isopropanol at the outlet of the final dehydration and polishing section was 8.7 ppm, the boron content was 19 ppt, the total metal content of Fe, Ni, Cr and Cu was 43 ppt, and the diacetone alcohol content was 112 ppb.

[0152] After 6 hours of continuous processing, the moisture content of isopropanol at the outlet of the final dehydration and polishing section increased to 18 ppm.

[0153] After 10 hours of continuous processing, the moisture content of isopropanol at the outlet of the final dehydration and polishing section increased to 26 ppm.

[0154] In this comparative example, the bulk phase water treatment can reduce the boron content, total metal content and diacetone alcohol content. However, when the isopropanol after water treatment enters the final dehydration and polishing section, the moisture content is too high, the moisture breakthrough time of the final dehydration and polishing section is shortened, and the moisture content of the finished isopropanol is difficult to maintain stably below 10 ppm during continuous processing.

[0155] Comparative Example 3 This comparative example uses 3A molecular sieve and 13X molecular sieve in series to treat pre-dehydrated isopropanol.

[0156] Isopropanol treated in the pre-dehydration stage in Example 2 was used as feed. The feed moisture content was 82 ppm, boron content was 84 ppt, Fe content was 37 ppt, Ni content was 26 ppt, Cr content was 30 ppt, Cu content was 35 ppt, the total amount of Fe, Ni, Cr and Cu metals was 128 ppt, and diacetone alcohol content was 410 ppb.

[0157] Pre-dehydrated isopropanol was sequentially passed into a 3A molecular sieve bed and a 13X molecular sieve bed. The 3A molecular sieve bed was used for further dehydration, and the 13X molecular sieve bed was used to adsorb polar organic impurities.

[0158] Both 3A and 13X molecular sieves underwent acid washing, ultrapure water washing, high-purity isopropanol replacement, and drying nitrogen purging.

[0159] During the treatment process, the temperature of both the 3A molecular sieve bed and the 13X molecular sieve bed was controlled at 25℃, the liquid flow rate was controlled at 1.0 BV / h, and the bed pressure was controlled at 0.10 MPa~0.15 MPa.

[0160] After being treated by a series of 3A and 13X molecular sieves, the water content of the isopropanol at the outlet is 7.5 ppm.

[0161] Tests revealed that the exported isopropanol contained 72 ppt of boron, 31 ppt of Fe, 22 ppt of Ni, 26 ppt of Cr, and 29 ppt of Cu. The total amount of Fe, Ni, Cr, and Cu metals was 108 ppt, and the diacetone alcohol content was 310 ppb.

[0162] After 10 hours of continuous treatment, the moisture content of the outlet isopropanol remained at 7.5 ppm to 9.2 ppm, the boron content remained at 72 ppt to 78 ppt, the total metal content of Fe, Ni, Cr and Cu remained at 108 ppt to 116 ppt, and the diacetone alcohol content remained at 310 ppb to 335 ppb.

[0163] In this comparative example, the tandem bed of 3A molecular sieve and 13X molecular sieve can reduce the moisture content of isopropanol and has a certain adsorption effect on diacetone alcohol. However, the boron content and total metal content remain at a high level, indicating that it is difficult to effectively remove borate ester impurities and complexed metal impurities by relying solely on conventional molecular sieve dehydration.

[0164] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0165] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the present invention. Various changes and modifications can be made to the present invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed.

Claims

1. A method for high-purity isopropanol adsorption dehydration and impurity removal purification for semiconductor cleaning, characterized in that, Includes the following steps: S1. Pass the isopropanol to be purified into the pre-dehydration section to obtain pre-dehydrated isopropanol with a bulk water content of not more than 500 ppm. S2. Pre-dehydrated isopropanol is introduced into the confined water activity stripping section, which is filled with a confined water activity adsorbent. Confined water activity adsorbents include boron trapping particles and metal trapping particles. Both boron trapping particles and metal trapping particles use mesoporous silica as an inorganic framework. The pore surface of boron trapping particles is covalently grafted with vicinal diol groups, and the pore surface of metal trapping particles is covalently grafted with imine diacetic acid groups. Boron-capturing particles and metal-capturing particles are mixed and placed in a high-purity nitrogen atmosphere for equilibration, allowing trace amounts of water to enter the mesoporous channels and form channel-bound water with hydroxyl, vicinal diol, and imine diacetic acid groups on the pore walls. The confined water activity adsorbent has mesoporous channels of 2 nm to 10 nm. The water filling rate θw of the confined water activity adsorbent is 5% to 45%. The water filling rate θw is the ratio of the volume of bound water Vw in the channel to the total pore volume Vp of the adsorbent. Among them, the mass increase of the adsorbent after drying to constant weight was measured as a reference, and the mass increase was converted into the volume of bound water in the pores Vw according to the density of water. The equilibrium water activity (aw) of the confined water activity adsorbent, measured in a closed system at 25°C, ranged from 0.15 to 0.

65. After the pre-dehydrated isopropanol passes through the confined water activity stripping section, the increase in bulk water content ΔW is no more than 100 ppm. When pre-dehydrated isopropanol passes through the confined water activity stripping section, borate ester impurities and complexed metal impurities undergo stripping or coordination transformation at the pore interface of the confined water activity adsorbent, forming interfacial retained impurities. S3. The isopropanol that has been treated by the confined water activity stripping section is passed into the final dehydration and polishing section to reduce the water content of the isopropanol to no more than 10 ppm, thereby obtaining high-purity isopropanol.

2. The method for high-purity isopropanol adsorption dehydration and impurity removal purification for semiconductor cleaning according to claim 1, characterized in that, In step S1, the bulk water content of the pre-dehydrated isopropanol is 10 ppm to 500 ppm; In step S2, the increase in bulk water content ΔW after the pre-dehydrated isopropanol passes through the confined water activity stripping section is 5 ppm to 100 ppm. In step S3, the isopropanol moisture content after the final dehydration and polishing section is no higher than 5 ppm.

3. The method for high-purity isopropanol adsorption dehydration and impurity removal purification for semiconductor cleaning according to claim 1, characterized in that, The preparation of boron capturing particles includes: grafting 3-glycidyl etheroxypropyltrimethoxysilane onto the surface of mesoporous silica channels, and then allowing the amino group in N-methyl-D-glucamine to undergo a ring-opening reaction with the epoxy group on the surface of the mesoporous channels to obtain boron capturing particles with vicinal diol groups covalently grafted onto the surface of the mesoporous channels. The preparation of metal trapping particles includes: grafting 3-aminopropyltriethoxysilane onto the surface of mesoporous silica channels, followed by carboxylation reaction with sodium chloroacetate to obtain metal trapping particles with imine diacetic acid groups covalently grafted onto the surface of the mesoporous channels. Boron trapping particles and metal trapping particles are mixed at a mass ratio of 7:

3.

4. A method for high-purity isopropanol adsorption dehydration and impurity removal purification for semiconductor cleaning according to claim 1, characterized in that, The confined water activity stripping section includes an interface conversion zone, an impurity fixation zone, and a water release buffer zone arranged sequentially along the isopropanol flow direction. The equilibrium water activity (aw) in the interface transition zone is 0.35–0.

65. The equilibrium water activity (aw) in the impurity fixation zone is 0.20–0.

45. The equilibrium water activity (aw) of the water release buffer zone is 0.15–0.30; Isopropanol passes sequentially through the interfacial transformation zone, the impurity fixation zone, and the water release buffer zone, causing boronic acid ester impurities and complexed metal impurities to first undergo interfacial stripping or coordination transformation, and then be fixed by the impurity capturing groups, thereby reducing the amount of pore-bound water released into the isopropanol bulk phase.

5. A method for high-purity isopropanol adsorption dehydration and impurity removal purification for semiconductor cleaning according to claim 1, characterized in that, The stripping efficiency value E of the confined water activity stripping section was determined by the reduction ratio of boron, the reduction ratio of metal, and the increase ratio of moisture. The stripping efficiency value E satisfies the following relationship: E=a·ΔB / Bin+b·ΔM / Min-c·ΔW / Wlim; Wherein, ΔB is the decrease in boron content before and after the confined water activity stripping section, Bin is the boron content before entering the confined water activity stripping section, ΔM is the decrease in metal content before and after the confined water activity stripping section, Min is the metal content before entering the confined water activity stripping section, ΔW is the increase in bulk moisture before and after the confined water activity stripping section, and Wlim is the allowable moisture limit before entering the final dehydration and polishing section. 'a' is the boron control coefficient, which ranges from 1.0 to 1.

5. b is the metal control coefficient, with a value ranging from 0.8 to 1.2; c is the water release penalty coefficient, which ranges from 0.6 to 1.0; When the stripping efficiency value E is lower than the set efficiency threshold, switch the confined water activity stripping section or regenerate the confined water activity stripping section.

6. A method for high-purity isopropanol adsorption dehydration and impurity removal purification for semiconductor cleaning according to claim 1, characterized in that, High-purity isopropanol at 20°C is introduced into the confined water activity stripping section to be regenerated at a flow rate of 0.5 BV / h and an injection volume of 3 BV. After the replacement is completed, dry nitrogen gas is introduced into the confined water activity stripping section. The dew point of the dry nitrogen gas is below -60℃, the purging temperature is 50℃, and the purging time is 4 hours. After the drying nitrogen purging is completed, high-purity nitrogen gas at a temperature of 25℃ and a relative humidity of 30% is introduced into the confined water activity stripping section for 3 hours. Then, ultra-dry isopropanol with a water content of 4.5 ppm is introduced into the confined water activity stripping section at a flow rate of 0.4 BV / h until the increase in water content of isopropanol at the adsorption column outlet relative to the inlet isopropanol is less than 30 ppm for three consecutive times.

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