JP5739687B2 - Alcohol purification method, apparatus and system - Google Patents

Description

The present invention relates to a method and apparatus for purifying alcohol, and more particularly, to a method and apparatus for purifying alcohol using an ion exchange resin, and an alcohol purification system using the alcohol purifier .

  Alcohols such as methyl alcohol, ethyl alcohol, and isopropyl alcohol (IPA) are widely and widely used as cleaning agents, solvents, and synthetic raw materials for the chemical industry. In particular, in the manufacture of semiconductor devices, a large amount of IPA is used for applications such as cleaning and drying. For example, the IPA evaporative drying method for removing moisture after performing pure water cleaning on a semiconductor device is effective as a process for removing moisture, but on the other hand, it requires high purity and high volatility. As a result, the manufacturing cost of the semiconductor device is increased. Accordingly, it is desired to recover and reuse the waste IPA used in the IPA evaporative drying method in terms of cost reduction and improvement of environmental load. The IPA discharged in the semiconductor device manufacturing process contains impurities derived from the manufacturing process, materials, and equipment. In order to recover and reuse the IPA, these impurities are highly removed. IPA needs to be purified.

  As a method for purifying contaminated alcohols containing impurities, for example, a distillation method as shown in Patent Document 1 is known. However, the distillation method has a high equipment cost, a large installation area, and a large amount of energy. Is not preferable in terms of economy. A method of removing metal ions using a precision evaporator is also used, but the method of using a precision evaporator also requires a large amount of energy and can remove impurities including boron and halogen-based elements. There is a problem that it is not possible.

  On the other hand, for example, as described in Patent Document 2, Patent Document 3, and Non-Patent Document 1, a method of purifying alcohol using an ion exchange resin is also known. The treatment with the ion exchange resin has lower energy consumption and equipment cost than the case of using a distillation apparatus, and advanced purification can be performed with simple equipment. Alcohol has a lower diffusion rate in the ion-exchange resin than water, and the reaction rate of the ion-exchange reaction with the ion-exchange resin is low, so when removing ionic impurities in the alcohol, an aqueous solution Compared with the case of removing ionic impurities therein, the flow rate for the ion exchange resin is set to be small. Therefore, the pressure loss due to the ion exchange resin layer becomes very small.

  However, a general ion exchange resin retains 40 to 60% of moisture inside the ion exchange resin after production. Although it is possible to replace moisture inside the ion exchange resin by passing alcohol through such ion exchange resin, there is a problem that a large amount of bubbles are generated in the ion exchange resin layer at the same time. Also occurs. This bubble is obtained by adding the saturated dissolution amount of a gas when two kinds of solvents (in this case, water and alcohol) are mixed by multiplying the saturated dissolution amount of each individual solvent by the mixing ratio of the solvent. This occurs when the alcohol and water contact or mix in the ion-exchange resin layer because the saturated solubility of the gas in water is smaller than the saturated solubility of the gas in alcohol. To do. In particular, it is considered that the alcohol recovered after being used for washing or evaporation and drying is dissolved in an amount of gas close to the saturated dissolution amount.

  When bubbles are generated in the resin layer, the phenomenon of a single flow where the liquid does not pass through the generation site of the bubbles occurs thereafter, so that the entire ion exchange resin cannot be fully used, and the efficiency of ion exchange decreases. Occurs. Bubbles in the ion exchange resin layer can be removed by backwashing the ion exchange resin layer or performing ascending flow liquid. However, in the case of a mixed bed ion exchange resin layer in which a cation exchange resin (CER) and an anion exchange resin (AER) are mixed, separation of the ion exchange resin occurs. I can't. Even if an ion exchange resin layer uses only a single ion exchange resin, impurities are adsorbed to the bottom of the resin layer due to backwashing, and the terminal resin layer is contaminated when liquid is passed through. From the viewpoint of obtaining this alcohol, it is preferable not to perform backwashing or the like.

  It is conceivable that the liquid is deaerated in advance before the ion exchange resin layer. In this case, examples of the deaeration method include a decompression method using a deaeration pump, an ultrasonic deaeration method, and a deaeration membrane. However, there is a problem such as an increase in cost, and it is not preferable to perform a deaeration process separately.

  Bubbles are not generated unless the alcohol passed through and the moisture inside the ion exchange resin are in contact with each other. For example, as shown in Patent Document 4, there is a method using an ion exchange resin from which moisture has been removed by a drying process. is there. However, by adding a drying step by heating operation, the amount of eluate from the ion-exchange resin matrix increases, which becomes an impurity in the alcohol to be purified, gel-type ion exchange resin and strongly basic anion exchange resin Regarding (SBAER), there is a problem that it is not possible to produce a product from which moisture has been removed.

JP-A-6-69175 JP 2009-57286 A JP-A-11-57304 JP 2004-181352 A

Partha V. Buragohain, William N. Gill, and Steven M. Cramer; "Novel Resin-Based Ultrapurification System for Reprocessing IPA in the Semiconductor Industry," Ind. Eng. Chem. Res., 1996, 35 (9), pp. 3149-3154

  As described above, the method of using an ion exchange resin as a method of purifying alcohols such as isopropyl alcohol has the advantage that advanced purification can be performed with simple equipment, but is included in the alcohol and the ion exchange resin. Air bubbles are generated by the contact with the generated water, and the ion exchange efficiency is lowered due to the air bubbles, and thus the purification efficiency of the alcohol is also lowered. As described above, methods for removing bubbles or suppressing the generation of bubbles have been proposed so far, but there are problems such as an increase in cost and the presence of ion-exchange resins that cannot be applied. ing.

An object of the present invention is a method and apparatus for purifying alcohol using an ion exchange resin, which does not cause an increase in cost, does not require a backwash operation, and generates bubbles in the ion exchange resin layer. Is to provide a method and apparatus capable of efficiently purifying high-purity alcohol, and an alcohol purification system using this alcohol purification apparatus .

  In order to solve the above problems, the present inventors have conducted intensive studies. As a result, when the alcohol-containing liquid is passed through an ion exchange column filled with an ion exchange resin and the alcohol is purified, for example, An ion exchange resin layer is provided by supplying alcohol into the ion exchange column so as to increase the pressure of the alcohol-containing liquid in the ion exchange column, which usually does not take place by providing a back pressure valve at the subsequent stage of the ion exchange column. The present invention was completed by finding that the generation of bubbles in the interior of the ion-exchange resin can be suppressed, the ion-exchange treatment of the alcohol-containing liquid can be performed efficiently, and the water in the ion-exchange resin can be rapidly replaced with alcohol. I came to let you.

  That is, in the method for purifying alcohol according to the present invention, bubbles are not generated by the contact between the alcohol-containing liquid and the ion exchange resin in the method for purifying the alcohol by treating the alcohol-containing liquid using an ion exchange tower filled with the ion exchange resin. Thus, the alcohol-containing liquid is supplied to the ion exchange tower while adjusting the pressure applied to the alcohol-containing liquid in the ion exchange tower.

  The alcohol purification apparatus of the present invention does not generate bubbles due to the contact between the ion-exchange column filled with the ion-exchange resin, the supply means for supplying the alcohol-containing liquid into the ion-exchange column, and the alcohol-containing liquid and the ion-exchange resin. Pressure adjusting means for adjusting the pressure applied to the alcohol-containing liquid in the ion exchange tower.

  In the present invention, by applying pressure to the alcohol-containing liquid in the ion-exchange column, the solubility of the gas in the alcohol-containing liquid is increased, and two types of solvents (water in the ion-exchange resin and the ion-exchange column are supplied. The amount of saturated dissolution of the gas when mixed with the reduced alcohol) is suppressed, and the retention of the liquid in the ion exchange resin layer is suppressed. Thereby, generation | occurrence | production of the bubble in an ion exchange resin layer does not occur, but it becomes possible to pass through an ion exchange tower, without an alcohol containing liquid retaining.

  In the present invention, the pressure applied to the alcohol-containing liquid in the ion exchange tower is preferably 0.055 MPa or more in terms of gauge pressure. As the ion exchange resin in the ion exchange tower, single bed type or multiple bed type can be used, but from the viewpoint of reducing the effluent while realizing high ion exchange efficiency, cation exchange with anion exchange resin It is preferable to use a mixed bed type in which a resin is mixed, particularly a mixed bed type in which a strong basic anion exchange resin and a strong acidic cation exchange resin are mixed.

  In the present invention, the pressure adjusting means for adjusting the pressure applied to the alcohol-containing liquid in the ion exchange tower so as not to generate bubbles in the ion exchange resin layer is a liquid feed pump for supplying the alcohol-containing liquid to the ion exchange tower, etc. The pressure in the ion exchange column may be adjusted in cooperation with the supply means. Examples of such pressure adjusting means include a back pressure valve and a relief valve that are provided in the subsequent stage of the ion exchange column and can raise the inside of the ion exchange column to a predetermined pressure. Further, there is a control means for opening the automatic valve when the pressure switch detects a predetermined pressure by the pressure switch provided in the ion exchange column and the automatic valve provided in the subsequent stage of the ion exchange column. .

  In the present invention, the alcohol contained in the alcohol-containing liquid, that is, the alcohol to be purified includes, for example, monohydric alcohols such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol (IPA), tert-butyl alcohol, Examples thereof include dihydric alcohols such as ethylene glycol and diethylene glycol, and trihydric alcohols such as glycerin. Among them, IPA, ethyl alcohol, and the like widely used in processes such as cleaning and evaporation drying in the manufacture of semiconductor devices are alcohols to which the present invention is preferably applied.

  According to the present invention, an alcohol can be passed through an ion exchange column without generating bubbles inside the ion exchange resin layer, whereby a purified alcohol having an ion exchange treatment and a stable liquid quality can be obtained. The effect of being able to ensure reliably is acquired. Moreover, the amount of alcohol required for the initial cleaning for reducing the water concentration at the outlet of the ion exchange tower can be greatly reduced. Furthermore, according to the present invention, since a backwash operation is not required, it is possible to use a mixed bed type ion exchange resin that has been difficult to use in the past.

It is a figure which shows the structure of the alcohol refiner | purifier of one Embodiment of this invention. It is a graph which shows the relationship between the initial substitution amount of alcohol, and the water concentration at the column exit. It is a figure which shows an example of a structure of an alcohol refinement | purification system.

  Next, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows an alcohol purifier according to an embodiment of the present invention. This alcohol refining apparatus is suitable for recovering and purifying alcohol such as isopropyl alcohol (IPA) used in the semiconductor device manufacturing process, and with respect to the ion exchange column 13 filled with ion exchange resin. Impurities are removed by passing alcohol.

  The alcohol-containing liquid, that is, the alcohol before purification is stored in the alcohol tank 11. A liquid feed pump 12 for supplying an alcohol-containing liquid from the alcohol tank 11 to the inlet side provided in the ion exchange tower 13 is provided. A back pressure valve 14 is attached to the outlet side provided in the ion exchange tower 13, and the purified alcohol can be taken out from the outlet 15 through the back pressure valve 14 from the ion exchange tower 13.

  The ion exchange resin in the ion exchange tower 13 adsorbs and removes ion components in the alcohol. For example, a cation exchange resin that adsorbs and removes cations such as sodium ion, calcium ion, potassium ion, iron ion, and aluminum ion, and anion exchange that adsorbs and removes anions such as chloride ion, sulfide ion, and borate ion. A mixed bed type ion exchange resin mixed with a resin is used. The specifications of the cation exchange resin and the anion exchange resin are determined according to the properties of the alcohol supplied to the alcohol tank 11 and the quality required for the purified alcohol taken out from the outlet 15. However, OH (hydroxide ion) type strongly basic anion exchange resin is used as anion exchange resin from the viewpoint of adsorption performance of ionic impurities and small amount of eluate from ion exchange resin itself. As the cation exchange resin, it is preferable to use a strong acidic cation exchange resin of H (hydrogen ion) form, and to use these in a mixed bed.

  The back pressure valve 14 is used when an alcohol-containing liquid is pumped into the ion exchange tower 13 from the liquid feed pump 12 and a certain pressure acts on the valve body by the purified alcohol that has passed through the ion exchange resin layer in the ion exchange tower 13. The valve body opens and discharges purified alcohol to the outlet 15. The constant pressure referred to in the present invention is a pressure at which bubbles are not generated due to contact between the alcohol-containing liquid and the ion exchange resin, and the gauge pressure is 0.055 MPa or more.

  In such an alcohol purifier, when an alcohol-containing liquid in which a gas is dissolved is supplied from the alcohol tank 11 to the ion exchange tower 13 by the liquid feed pump 12, the alcohol-containing liquid removes ionic impurities with an ion exchange resin. The purified alcohol is obtained from the outlet 15. At this time, pressure is applied to the alcohol-containing liquid in the ion exchange tower 13 by the back pressure valve 14, so that bubbles are generated in the ion exchange resin layer even if the alcohol and moisture in the ion exchange resin come into contact with each other. It is suppressed. In addition, the flow direction in the ion exchange column 13 is from the top to the bottom of the column, and problems such as separation of the anion exchange resin and the cation exchange resin are caused even when a mixed bed type ion exchange resin is used. Does not occur.

  Hereinafter, the present invention will be described in more detail with reference to examples of isopropyl alcohol (IPA) purification and comparative examples.

[Example 1]
The alcohol purification apparatus shown in FIG. 1 was manufactured using a cylindrical column made of PFA (tetrafluoroethylene-perfluoroalkoxyethylene copolymer) having an inner diameter of 16 mm and a height of 30 cm as the ion exchange tower 13. In the column, gel-type mixed bed ion exchange resin (mixture of strongly basic anion exchange resin and strong acid cation exchange resin) ESG-2 (trade name) made by Organo, 50 mL (25 cm in layer height) Filled. For filling the ion exchange resin, IPA having a water concentration of less than 0.1% was used.

  In such a column, the flow rate is set to SV10 (SV indicates how many times the liquid flows with respect to the ion exchange resin on a volume basis per unit time), and the primary side of the back pressure valve 14 by the back pressure valve 14 Was set to 0.055 MPa (gauge pressure), and IPA having a water concentration of less than 0.1% was passed. And the bubble generation | occurrence | production condition in a column was confirmed, and the change of the moisture concentration in the exit 15 was measured. The results are shown in Table 1 and FIG.

  In Example 1, generation | occurrence | production of the bubble in a column was not confirmed. In addition, the water concentration at the column outlet steadily decreased with the increase in the accumulated flow rate.

［実施例２］
背圧弁１４の一次側の圧力が０．０６５ＭＰａとなるように背圧弁１４を設定したほかは実施例１と同様の条件で試験を行った。結果を表１に示す。カラム内における気泡の発生は確認されなかった。

[Example 2]
The test was performed under the same conditions as in Example 1 except that the back pressure valve 14 was set so that the pressure on the primary side of the back pressure valve 14 was 0.065 MPa. The results are shown in Table 1. Generation | occurrence | production of the bubble in a column was not confirmed.

[Comparative Example 1]
The test was performed under the same conditions as in Example 1 except that the back pressure valve 14 was set so that the pressure on the primary side of the back pressure valve 14 was 0.035 MPa. The results are shown in Table 1 and FIG.

  It was confirmed that a large amount of bubbles were generated in the column. Further, regarding the water concentration at the column outlet, a phenomenon was observed in which the water concentration temporarily increased as the alcohol-containing liquid flowed. The reason why the moisture concentration temporarily increased was that the part that was not passed through the ion exchange resin layer due to the generation of bubbles was newly passed through the movement of the bubbles. Conceivable.

[Comparative Example 2]
The test was performed under the same conditions as in Example 1 except that the back pressure valve 14 was set so that the primary pressure of the back pressure valve 14 was 0.045 MPa. The results are shown in Table 1. Generation of a small amount of bubbles in the column was confirmed.

[Comparative Example 3]
When the gel-type mixed bed ion exchange resin is packed into the PFA column, 100 ml of IPA having a moisture concentration of less than 0.1% is used for the purpose of preliminarily replacing the moisture inside the ion exchange resin with IPA. Then, after batch immersing the ion exchange resin for 10 minutes and discarding the supernatant, the same batch immersing operation was repeated two more times, and then the column was filled with the ion exchange resin. The other operations were tested under the same conditions as in Comparative Example 1. The results are shown in Table 1.

  Although the water concentration in the ion exchange resin layer was previously reduced by the batch immersion operation, a large amount of bubbles was confirmed in the column.

[Example 3]
Whether or not bubbles were generated in the column when the pressure applied to the alcohol-containing liquid in the ion exchange tower 13 was changed was examined.

  After passing IPA twice as much as the amount of ion-exchange resin under the same flow conditions as in Example 1, and confirming that no bubbles were generated in the column, the primary pressure of the back pressure valve 14 was 0.035 MPa. Then, the back pressure valve 14 was set so that the amount of IPA was passed twice as much as the amount of ion-exchange resin, and it was confirmed that bubbles were generated in the column.

  Subsequently, the setting of the back pressure valve 14 was returned so that the primary pressure of the back pressure valve 14 became 0.055 MPa, and IPA was passed through twice the amount of the ion exchange resin. As a result, no bubbles in the column were confirmed.

  From the above results, it is preferable to set the pressure applied to the alcohol-containing liquid in the ion exchange column 13 to 0.055 MPa or higher regardless of whether or not the ion exchange resin is previously subjected to the treatment for reducing the water concentration. I understood that.

  Next, an alcohol purification system incorporating an alcohol purification apparatus according to the present invention will be described with reference to FIG.

  FIG. 3 shows an example of the configuration of an alcohol purification system used for purifying IPA collected from a cleaning process or evaporation drying process in semiconductor device manufacturing and recycling it again to the cleaning process or evaporation drying process. Show. The apparatus used for carrying out the cleaning process or the evaporation drying process is collectively referred to as a semiconductor manufacturing apparatus 30.

  A supply tank 31 for supplying alcohol to the semiconductor manufacturing apparatus 30 and a recovery tank 32 for holding alcohol recovered from the semiconductor manufacturing apparatus 30 are provided. The alcohol purification system 20 includes an ion exchange tower 22 filled with an ion exchange resin, a liquid feed pump 21 that supplies alcohol from a recovery tank 32 to the top of the ion exchange tower 22, and a flow at the bottom of the ion exchange tower 22. From a back pressure valve 23 provided at the outlet, a water removing device 24 for removing water from the purified alcohol flowing out through the back pressure valve 23, and an alcohol provided on the outlet side of the water removing device 24 and purified to remove water. A metal removing device 25 that removes metallic impurities and a fine particle removing device 26 that is provided on the outlet side of the metal removing device 25 and removes fine particles (particles) are provided. Purified alcohol flowing out from the particulate removing device 26 is circulated to the supply tank 31. The supply tank 31 is also supplied with supplemental alcohol. In this configuration, the liquid feed pump 21, the ion exchange tower 22 and the back pressure valve 23 constitute an alcohol purifier similar to that shown in FIG.

  In the alcohol purification system 20 shown in FIG. 3, since the generation of bubbles in the ion exchange resin layer is suppressed when the alcohol is passed through the ion exchange tower 22, the alcohol can be purified stably, and thus the semiconductor The alcohol collected from the manufacturing apparatus 30 can be purified and recycled to the semiconductor manufacturing apparatus 30 stably.

DESCRIPTION OF SYMBOLS 11 Alcohol tank 12,21 Liquid feed pump 13,22 Ion exchange tower 14,23 Back pressure valve 15 Outlet 20 Alcohol purification system 24 Moisture removal apparatus 25 Metal removal apparatus 26 Fine particle removal apparatus 30 Semiconductor manufacturing apparatus 31 Supply tank 32 Recovery tank

Claims (12)

An ion exchange column filled with an ion exchange resin;
Supply means for supplying an alcohol-containing liquid into the ion exchange tower;
Pressure adjusting means for adjusting a pressure applied to the alcohol-containing liquid in the ion-exchange tower so that bubbles are not generated by contact between the alcohol-containing liquid and the ion-exchange resin;
An alcohol refining apparatus.   The alcohol purification apparatus according to claim 1, wherein the pressure adjusting means sets a pressure applied to the alcohol-containing liquid in the ion exchange column to 0.055 MPa or more in terms of gauge pressure. The alcohol purification apparatus according to claim 1 or 2, wherein the pressure adjusting means is a back pressure valve or a relief valve provided at a subsequent stage of the ion exchange column. The alcohol purification apparatus according to any one of claims 1 to 3, wherein the ion exchange resin is in a gel form. The ion exchange resin is an ion exchange resin mixed bed obtained by mixing a cation exchange resin and an anion exchange resin, the alcohol purification apparatus according to any one of claims 1 to 4.   The alcohol purifier according to any one of claims 1 to 5, wherein the alcohol-containing liquid is a liquid containing isopropyl alcohol, and purifies isopropyl alcohol. In a method of purifying alcohol by treating an alcohol-containing liquid using an ion exchange tower filled with an ion exchange resin,
Supplying the alcohol-containing liquid to the ion-exchange tower while adjusting the pressure applied to the alcohol-containing liquid in the ion-exchange tower so that bubbles are not generated by contact between the alcohol-containing liquid and the ion-exchange resin. A method characterized by.   The method according to claim 7, wherein the pressure applied to the alcohol-containing liquid in the ion exchange column is 0.055 MPa or more in terms of gauge pressure. The method according to claim 7 or 8, wherein the pressure applied to the alcohol-containing liquid in the ion exchange column is adjusted by a back pressure valve or a relief valve provided at the rear stage of the ion exchange column. The method according to claim 7, wherein the ion exchange resin is in a gel form. The ion exchange resin is an ion exchange resin mixed bed obtained by mixing a cation exchange resin and an anion exchange resin, the method according to any one of claims 7 to 10. The alcohol purifier according to any one of claims 1 to 6,
A water removal device for removing water in the alcohol purified by the alcohol purification device;
An alcohol purification system.

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