JP2000203811A - Packed column and purification of aqueous hydrogen peroxide using the same packed column - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide both a packed column filled with packings for treating an aqueous hydrogen peroxide capable of realizing an extremely advantageous technique from aspects of industrial practice and a method for purifying the aqueous hydrogen peroxide using the packed column. SOLUTION: This packed column 3 is filled with packings 4 for treating an aqueous hydrogen peroxide in the interior of a void column and has the following characteristics (A) to (E): (A) having a liquid inlet 5 in the lower part of the column 3 and a liquid outlet 6 in the column lateral face in the upper part of the column 3, (B) having a spatial part 8 between the ceiling surface 7 of the column 3 and the liquid outlet 6, (C) having the topmost surface 9 in a layer of the packings 4 below the liquid outlet 6, (D) having a ventilating hole 10 in the upper part of the column 3 and (E) having liquid jetting nozzles 11 installed in the upper part in the interior of the column 3 and capable of jetting a liquid on the topmost surface 9 of the layer of the packings 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a packed column and a method for purifying hydrogen peroxide using the packed column. More specifically, the present invention is a technology for removing impurities in hydrogen peroxide water by subjecting the hydrogen peroxide water to a contact treatment with a packing for treating hydrogen peroxide water. Is not dangerous because of its rapid decomposition, and the effect of removing impurities is reduced, which makes continuous operation difficult for a long period of time. Packing tower for hydrogen peroxide water treatment packing, which has the feature that continuous operation over a long period of time is possible, and can realize a very advantageous technique from the viewpoint of industrial implementation, and peroxide using the packing tower The present invention relates to a method for purifying hydrogen water.

[0002]

2. Description of the Related Art In a semiconductor manufacturing process, an aqueous solution of hydrogen peroxide is used as one component of a cleaning solution for a wafer.
The hydrogen peroxide solution used here is required to be highly clean and pure. In particular, it is said that the presence of metal impurities such as iron ions and aluminum ions, anionic impurities such as nitrate, and impurities such as TOC in hydrogen peroxide water significantly reduces the reliability of the obtained semiconductor. On the other hand, the required level of semiconductor reliability is
In recent years, it has become increasingly sophisticated, and there is an increasing need for high-purity aqueous hydrogen peroxide in which impurities are controlled to extremely low levels. Meanwhile, as a method for purifying hydrogen peroxide water, a method is known in which hydrogen peroxide water is brought into contact with a filler such as an anionic resin or a chelate resin filled in a packed tower to remove impurities. However, according to the conventional method, rapid decomposition of hydrogen peroxide occurs during continuous operation, which is dangerous, and the effect of removing impurities is reduced, thus making continuous operation difficult for a long period of time. From the point of view of practical implementation.

[0003]

Under such circumstances, the problem to be solved by the present invention is to remove impurities in the hydrogen peroxide solution by subjecting the hydrogen peroxide solution to a contact treatment with a packing for treating hydrogen peroxide solution. This is a technology that removes hydrogen, which is dangerous because rapid decomposition of hydrogen peroxide occurs during continuous operation and reduces the effect of removing impurities, thus making continuous operation difficult for a long period of time. Hydrogen peroxide solution, which has the feature that it can be operated continuously for a long period of time with good results without causing any inconvenience from the viewpoint of It is an object of the present invention to provide a packed tower of a packing for treatment and a method for purifying hydrogen peroxide using the packed tower.

[0004]

That is, a first aspect of the present invention is a packed tower (3) in which an empty tower is filled with a packing (4) for treating hydrogen peroxide water. A) ~
The present invention relates to a packed tower having the feature (E). (A): A liquid inlet (5) is provided at the lower part of the tower, and a liquid outlet (6) is provided at the upper side of the tower. (B): A space between the ceiling surface (7) of the tower and the liquid outlet. (C): Having the uppermost surface (9) of the packed layer below the liquid outlet (D): Having a vent (10) at the top of the tower (E): Having the tower (8) Having a liquid jet nozzle (11) installed at the upper part of the inside and capable of jetting liquid to the uppermost surface of the layer of filling material

[0005] In the present invention, the second invention supplies a crude hydrogen peroxide solution from the liquid inlet of the packed tower of the first invention and obtains a fine hydrogen peroxide solution from the liquid outlet. The present invention relates to a method for purifying a hydrogen peroxide solution in which a hydrogen peroxide solution is injected from a liquid ejection nozzle to the uppermost surface of a layer of a filler to perform purification.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION First of all, the present inventors have first considered the above-mentioned problems of the prior art, that is, rapid decomposition of hydrogen peroxide during continuous operation is dangerous, and the effect of removing impurities is reduced. Then, the cause of the problem that continuous operation for a long period of time becomes difficult was examined, and the following conclusion was reached. That is, part of the hydrogen peroxide is decomposed in the packed tower to generate oxygen gas, which adheres to the packing, so that the packing reaches the top of the packed tower together with the oxygen gas. According to the prior art, the packing and the oxygen gas coagulate and stay at the top of the packed tower, and the passage of the hydrogen peroxide solution is hindered. As a result, rapid decomposition of the hydrogen peroxide occurs partially. In addition, the decomposition of the packing material occurs due to the temperature rise, and the hydrogen peroxide solution flowing through the packing material flows in a deviated flow, preventing the optimal contact between the packing material and the hydrogen peroxide solution, thereby removing impurities. Decrease. Furthermore, the present inventors have studied a method for solving the above-mentioned problem, and have reached the present invention described below.

[0007] The packed tower of the present invention is obtained by packing an empty tower with a packing for treating hydrogen peroxide water, and is suitable for packing which decomposes hydrogen peroxide and foams it. Examples thereof include an anion exchange resin, a cation resin and a chelate resin which adsorb a large amount of impurities that decompose hydrogen peroxide such as activated carbon, activated alumina and iron. Further, even those which do not directly decompose hydrogen peroxide can be applied to those having a small specific gravity and easy to float, such as an adsorption resin. Of course, two or more of these fillers may be used as a mixture.
Since the filler easily floats when the particle size is too small, in the case of an ion exchange resin, a commercially available one having a uniform particle size grade may be used. It is preferable to remove particles having a relatively small particle size.

The packed tower of the present invention has a liquid inlet at the lower part of the tower, a liquid outlet at the upper side of the tower, and a space between the ceiling surface of the tower and the liquid outlet. I need to do that.
That is, the liquid supplied to the packed tower moves in the tower as an upward flow from bottom to top. The liquid outlet must be provided on the side of the tower and have a space between the ceiling surface of the tower and the liquid outlet. That is, unlike the conventional packed tower, a liquid outlet must not be provided on the ceiling surface of the tower. The liquid outlet does not need to be limited to one place, and may have two or more places in some cases in order to secure a necessary flow rate. According to the present configuration of the present invention, oxygen gas is collected in the above-mentioned space, and is appropriately discharged from a vent provided in an upper portion of a tower described later. It is desirable to provide a strainer made of fluororesin or the like at the top of the tower in order to prevent the resin from flowing out.
The mesh size of the strainer is selected so that the packing does not flow out, and usually the mesh size is 0.05 to 0.2 mm. The strainer can be installed above the liquid outlet and / or above the top surface of the packing layer. However, since the packing and the oxygen gas are easily aggregated and stagnate, the strainer is positioned in parallel with the top surface of the packing layer. It is not so preferable to provide it at a position. Further, in order to ensure that the filler is not mixed into the product, a strainer having a mesh size equal to or less than the same diameter or a filter having a pore size of 10 μm to 0.05 μm may be provided outside the packed tower.

The packed tower of the present invention must have a vent at the top of the tower. As described above, the oxygen gas collected in the space above the tower is discharged by the vent. By connecting an oxygen gas amount measuring device to the vent hole, it is possible to constantly monitor the decomposition state of hydrogen peroxide. Decomposition of hydrogen peroxide varies depending on the packing, liquid temperature, and the like. Further, a measuring instrument or the like capable of monitoring the temperature, the pressure in the tower, and the differential pressure may be provided. Also, in order to prevent outside air from entering the packed tower through the vent and contaminate the hydrogen peroxide solution, the packed tower itself is installed in a clean room, and if that is not possible, the outlet of the vent is sealed with sealing water. It is desirable to take measures such as When the operation is performed in a situation where a large amount of oxygen gas is generated, the oxygen gas may be diluted by cutting nitrogen gas or the like into the outlet of the vent hole for safety considerations.

[0010] The packed tower of the present invention is required to have a liquid jet nozzle installed at the upper part of the tower and capable of jetting liquid to the uppermost surface of the packed bed. This prevents agglomeration and stagnation of the filler and oxygen gas.
When a strainer is provided at the liquid outlet, the liquid may also be jetted to the strainer. Since the shape and number of the ejection nozzles vary depending on the size of the packed tower and the type of packing material, they cannot be unconditionally determined, but are not particularly limited as long as the above object is achieved. Examples of the liquid to be jetted here include ultrapure water and hydrogen peroxide. As a method for preventing agglomeration and stagnation of the packing material and oxygen gas, there is another method of stirring with a stirrer or applying vibration to the packed tower, and these may be used in combination, but the liquid injection method of the present invention is the most efficient. Is good.

A strainer for preventing resin from flowing out is provided below the packed tower of the present invention. As a strainer, for example, a fluororesin disk with a large number of holes, a fluororesin net is spread, or a disk-shaped Teflon plate with a large number of slits with a gap of 0.1 to 0.2 mm, etc. However, any material having sufficient strength and capable of achieving the above object can be used. In addition, a dispersion plate for maintaining good dispersion of the liquid in the packed tower may be provided. As the dispersion plate, for example, there is a cone-type dispersion plate.

It is preferable that no empty nozzle is present in the packed portion of the packed tower according to the present invention, and if it is unavoidable, a blind flange having a shape such that the filled material cannot enter the empty nozzle. It is better to attach. It is preferable to have a structure with as few dead parts as possible at a place other than an empty nozzle, such as a place where a thermometer is installed.

The material used for the packed tower of the present invention is stainless steel, low-elution type vinyl chloride resin, PF
A, fluorine resin such as PTFE and the like are used. Further, stainless steel or carbon steel coated or lined with a low-elution type vinyl chloride resin or a fluororesin such as PFA or PTFE can also be used. Similar materials are used for the pipes connected to the packed tower, the liquid contact part of the instrumentation equipment, and the like.

Next, the second invention of the present invention will be described. The second invention is a method for purifying a hydrogen peroxide solution in which a crude hydrogen peroxide solution is supplied from a liquid inlet of the packed tower of the first invention and a purified hydrogen peroxide solution is obtained from a liquid outlet, wherein the liquid jetting is performed. The present invention relates to a method for purifying a hydrogen peroxide solution in which a hydrogen peroxide solution is sprayed from a nozzle onto the uppermost surface of a layer of the filler to perform purification. As the hydrogen peroxide solution to be purified, hydrogen peroxide solution industrially produced by an anthraquinone method or the like or industrial hydrogen peroxide solution is roughly purified using a chelate resin or a reverse osmosis membrane device. Hydrogen oxide water can be used. The concentration of the aqueous hydrogen peroxide is not particularly limited, but is usually 1 to
It is 65% by weight, preferably 1 to 40% by weight.

Before the hydrogen peroxide solution is introduced into the packed tower, bubbles present in the liquid may be removed in advance by a gas trap or the like. The aqueous hydrogen peroxide passes through the packed tower while being in contact with the packing, while passing through the packed tower. The liquid passing speed varies depending on the type of the packing, but is usually 0.1 to 100 hour ^-1 in SV (space velocity), Preferably 2 to 50 hou
r ⁻¹ . The liquid temperature controls the decomposition of hydrogen peroxide,
The temperature is preferably 30 ° C. or lower, more preferably 15 ° C. or lower. Examples of the cooling method include a method of passing a hydrogen peroxide solution through a multi-tube heat exchanger and a method of directly cooling the packed tower itself using a jacket. The packed tower and piping may be covered with a heat insulating material in some cases. Further, as the liquid used for the injection to the uppermost surface of the packed layer, a hydrogen peroxide solution having a quality equal to or higher than the quality of the outlet of the packed tower is used. There are industrial hydrogen peroxide solutions and those obtained by fractionating a part of purified hydrogen peroxide solution that has passed through the packed tower. The optimal injection speed varies depending on the type of the filling material and the like, but usually, the injection speed may be about 0.5 to 3 times the flow rate.

By using the packed tower of the present invention, it is possible to carry out the purification of the hydrogen peroxide solution very safely, but it is necessary to attach a safety device such as a rupture disk for further safety. Is also possible.

[0017]

The present invention will be described below with reference to examples and comparative examples. Example 1 Inside the empty tower (155mmφ × 1200mmH)
A packed tower filled with 9 liters of Haas' weakly basic anion exchange resin A-368, having a liquid inlet at the bottom of the tower, and a fluororesin strainer (having a mesh size of 0. 12 mm), a space (approximately 5 L) between the ceiling surface of the tower and the liquid outlet, and the uppermost surface of the filled anion exchange resin below the liquid outlet. And, having a liquid ejection nozzle that is installed at the upper part of the tower and can inject liquid to the uppermost surface of the anion exchange resin,
An anion-exchange resin packed tower having a vent at the top of the tower is used, and a 31% by weight crude material containing 2 wt ppb of iron ions, 72 ppb of aluminum ions, and 1 wt ppm of nitrate ions as impurities from the liquid inlet of the packed tower. Hydrogen oxide water is supplied at a rate of 45 L / hour (SV = 5 hour ^-1 ) by ascending flow, and purification is performed while jetting hydrogen peroxide solution at a rate of 60 L / hour from the liquid ejection nozzle to the top surface of the anion exchange resin. went. The crude hydrogen peroxide solution is supplied to a heat exchanger for 12 hours.
The solution was cooled to ℃ and passed. Prior to use, the anion exchange resin was washed with ultrapure water at SV = 10 hour ^-1 for 1 hour, and then passed with 6% by weight hydrochloric acid at SV = 5 hour ^-1 for 1 hour, and replaced with ultrapure water. Then, a 6% aqueous sodium hydroxide solution was passed at SV = 5hour ^-1 for 2 hours to convert to a hydroxyl form. After replacing with ultrapure water again, finally, a 6% aqueous sodium hydrogen carbonate solution was passed at SV = 5hour ^-1 for 2 hours.
Replaced with ultrapure water. Purification was performed continuously for 250 hours, but the amount of oxygen gas generated after 250 hours was 0.5 L /
Hour · L-Resin, which could be carried out extremely stably without causing a problem of a sharp rise in temperature or a decrease in the effect of removing impurities. The iron ion concentration in the purified hydrogen peroxide solution was 1 wt. Ppb or less, the aluminum ion concentration was 1 wt. Ppb, and the nitrate ion concentration was 0.1 wt. Ppm or less.

COMPARATIVE EXAMPLE 1 A conventional packed tower having a liquid outlet on the ceiling surface of a tower, having no space between the ceiling surface and the liquid outlet, and having no liquid ejection nozzle and a vent hole at the top of the tower. An experiment was performed in the same manner as in Example 1 except that the test was used. As a result, the amount of oxygen gas generated after 30 hours increased to 12 L / hour · L-Resin or more, and the temperature of the upper resin layer increased to 87 ° C., so the purification was stopped. At this time, the concentration of iron ions in the hydrogen peroxide solution after purification was 1 wt ppb, the concentration of aluminum ions was 10 wt ppb, and the concentration of nitrate ions was 0.2 wt pp.
m.

[0019]

As described above, according to the present invention, there is provided a technique for removing impurities in a hydrogen peroxide solution by subjecting the hydrogen peroxide solution to a contact treatment with a packing for treating a hydrogen peroxide solution. During the operation, rapid decomposition of hydrogen peroxide occurs, which is dangerous and reduces the effect of removing impurities, which makes continuous operation for a long period of time difficult, which is extremely inconvenient from the viewpoint of industrial implementation. Without the accompanying characteristics, it is possible to continuously operate for a long period of time under good results, and a packed column of hydrogen peroxide water treatment packing capable of realizing a very advantageous technology from the viewpoint of industrial implementation and A method for purifying hydrogen peroxide using the packed column could be provided.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of the present invention.

[Description of Signs] 1 Crude hydrogen peroxide solution 2 Purified hydrogen peroxide solution 3 Packing tower 4 Packing for hydrogen peroxide solution treatment 5 Liquid inlet 6 Liquid outlet 7 Tower ceiling surface 8 Space portion 9 Filling layer Top 10 Vent hole 11 Liquid ejection nozzle 12 Liquid outlet strainer 13 Liquid ejection nozzle supply hydrogen peroxide

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4D025 AA10 AB11 AB20 AB22 AB38 BA13 BB02 BB07 4G075 AA14 BA05 BB04 BB08 BD04 BD16 CA55 EB09 EC01

Claims (4)

[Claims] 1. A packed tower (3) in which an empty tower is filled with a packing (4) for treating aqueous hydrogen peroxide, comprising:
A packed tower having the characteristics of (E). (A): A liquid inlet (5) is provided at the lower part of the tower, and a liquid outlet (6) is provided at the upper side of the tower. (B): A space between the ceiling surface (7) of the tower and the liquid outlet. (C): Having the uppermost surface (9) of the packed layer below the liquid outlet (D): Having a vent (10) at the top of the tower (E): Having the tower (8) Having a liquid jet nozzle (11) installed at the upper part of the inside and capable of jetting liquid to the uppermost surface of the layer of filling material 2. In addition to (A) to (E) according to claim 1,
The packed tower according to claim 1, which has the following feature (F). (F): The strainer (12) is installed at the liquid outlet, and the strainer is not in a positional relationship parallel to the uppermost surface of the packing layer. 3. The packed column according to claim 1, wherein the packing for treating hydrogen peroxide is an anion exchange resin. 4. A method for purifying hydrogen peroxide, comprising supplying crude hydrogen peroxide from a liquid inlet of the packed tower according to claim 1 and obtaining purified hydrogen peroxide from a liquid outlet. A method for purifying a hydrogen peroxide solution in which the hydrogen peroxide solution is injected from a nozzle onto the uppermost surface of the layer of the packing to purify the solution.