JP3328854B2 - Concentration and purification method of hydrogen peroxide - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for providing a high-purity aqueous hydrogen peroxide solution by concentrating and purifying a crude aqueous hydrogen peroxide solution obtained by an anthraquinone method. Hydrogen peroxide obtained by the method of the present invention is as hydrogen peroxide for electronics industry where high purity is required, or as a raw material for further purification to obtain ultra-high purity hydrogen peroxide in semiconductor production. It is widely used industrially as a wide range of reaction reagents.

[0002]

2. Description of the Related Art At present, hydrogen peroxide is industrially produced by auto-oxidation of anthraquinone. Hereinafter, this method is referred to as “anthraquinone method”. In the anthraquinone method, generally, a 2-alkylanthraquinone is hydrogenated in a water-insoluble solvent in the presence of a hydrogenation catalyst to form a corresponding anthrahydroquinone. In this method, hydrogen peroxide is obtained by regenerating the hydrogen peroxide and extracting it with water. Since the aqueous solution containing hydrogen peroxide contains a considerable amount of organic impurities consisting of anthraquinones, solvents and their degradation products, it is common to extract and purify the organic impurities with a water-insoluble solvent. The aqueous hydrogen peroxide solution thus obtained is hereinafter referred to as “crude hydrogen peroxide aqueous solution”. The crude hydrogen peroxide aqueous solution contains 15 to 40% by weight of hydrogen peroxide, but the concentration of hydrogen peroxide usually used industrially is 30%.
The crude hydrogen peroxide is further concentrated because it is between 70 and 70% by weight.

A method for rectifying and condensing crude hydrogen peroxide is disclosed in US Pat.
No. 073755, British Patent 1326282, Japanese Patent Publication No. 37-8256, Japanese Patent Publication No. 45-34926, and the like, and the flow shown in the flow diagram of FIG. 1 is general in principle. In FIG. 1, the crude hydrogen peroxide enters the evaporator 2 from the line 1 and passes through the line 3 to the gas-liquid separator 4. At 4, the mixture is separated into a hydrogen peroxide aqueous solution containing a vapor composed of volatile impurities, hydrogen peroxide, and water and a non-volatile impurity and being in equilibrium with the composition on the vapor side. The vapor separated in 4 enters the rectification column 6 via line 5. 6
In the above, the rising steam reduces the concentration of hydrogen peroxide, the descending solution increases the concentration of hydrogen peroxide, and a concentrated aqueous hydrogen peroxide solution is withdrawn from the line 11 from the bottom of the tower. The vapor at the top is line 7
The condensed water substantially free of hydrogen peroxide is discharged from a line 10 through a condenser 8 and reflux water is supplied from a line 9 to the top of the tower. The aqueous hydrogen peroxide solution separated by the gas-liquid separator 4 is circulated to the evaporator 2, but a part of the aqueous solution is extracted from the line 12 to prevent accumulation of impurities.
These evaporation, gas-liquid separation, and rectification are usually performed under reduced pressure.

[0004] Hydrogen peroxide aqueous solution is widely used not only as a reaction reagent but also in many fields such as bleaching and chemical polishing, but in recent years, its use in the electronics industry such as semiconductors and printed wiring boards has increased. Accordingly, an extremely high-purity aqueous solution of hydrogen peroxide has been required, and products obtained by rectifying and condensing crude hydrogen peroxide have also been required to have high-purity quality with very few impurities. However, there are many problems when trying to reduce organic impurities and inorganic impurities as much as possible with these conventional techniques. Crude hydrogen peroxide contains, as impurities, inorganic impurities resulting from elution from a reactor, piping, etc., in addition to organic impurities having a small but not negligible concentration. In some cases, it may contain a stabilizer added to suppress the decomposition of hydrogen peroxide in the production process. Therefore, if the gas-liquid separation in the gas-liquid separator in the evaporation step is incomplete, the inorganic impurities and the non-volatile organic impurities contained in the crude hydrogen peroxide aqueous solution are mixed into the rectification column in the form of mist and concentrated. This will contaminate the hydrogen oxide aqueous solution.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to evaporate a crude aqueous hydrogen peroxide solution in an evaporator, separate the generated steam from the liquid, supply it to a rectification column, and concentrate it. Solves the problem that part of the crude hydrogen peroxide aqueous solution is mixed into the rectification column due to incompleteness, and the purity of the concentrated purified liquid is reduced due to organic or inorganic impurities contained in the crude hydrogen peroxide. To supply pure hydrogen peroxide. In particular, an object of the present invention is to provide a gas-liquid separation method suitable for the physical properties of hydrogen peroxide.

[0006]

The present invention will be described with reference to a flow diagram shown in FIG. The crude aqueous hydrogen peroxide solution enters the evaporator 24 through line 21. The gas-liquid that has exited 24 is led through a line 25 to a cyclone 26. 2
At 6, the mixture is separated into a hydrogen peroxide aqueous solution containing a vapor composed of volatile impurities, hydrogen peroxide and water and a non-volatile impurity and being in equilibrium with the composition on the vapor side. The steam separated in 26 is sent to line 2
After 7 enter the second stage cyclone 28. Cyclone 28
The steam having exited from the mist is further led to a third-stage cyclone 30, and the steam from which mist has been completely removed passes through a line 31 and is preferably discharged to a bottom of a rectification column 32. Cyclone 2
The aqueous hydrogen peroxide solution separated at 6, 28, 30 is withdrawn from line 41 via lines 38, 39, 40. In the rectification column 32, the ascending vapor reduces the hydrogen peroxide concentration and the descending liquid increases the hydrogen peroxide concentration, and is withdrawn from the line 37 as a high-purity aqueous hydrogen peroxide solution concentrated from the bottom of the column. The vapor at the top is led to a condenser 34 through a line 33, and condensed water substantially free of hydrogen peroxide is discharged from a line 36, and reflux water is supplied to the top from a line 35. These evaporation, gas-liquid separation, and rectification are performed under reduced pressure. The hydrogen peroxide extracted from the line 37 is collected in a tank, stored, transported, and shipped.

The crude aqueous hydrogen peroxide solution used in the present invention contains 15 to 40% by weight of hydrogen peroxide, contains about 10 to 200 ppm of organic impurities as total organic carbon, and iron and aluminum ions derived from the material of the apparatus as inorganic impurities. From several tens to several hundreds of ppb. If necessary, a stabilizer such as a pyrophosphate salt alone or as a mixture containing a total concentration of up to 200 ppm is used.

[0008] The concentration and purification method of the present invention is characterized in that a gas-liquid separator is arranged in series with multiple stages of cyclones, and the gas-liquid separator is an important part constituting the method of the present invention. The gas leaving the evaporator contains a mist-like liquid, and since the liquid contains a high concentration of impurities, it is necessary to separate them. Gas-liquid separation methods include packing columns and mist separators of the collision plate type.However, these have a large area where gas-liquid comes into contact with the vessel wall and packing material, so that hydrogen peroxide decomposes and hydrogen peroxide comes into contact. There is a problem that contamination occurs due to elution from the equipment to be used. We repeated our research with a cyclone that was structurally simple, and found that good gas-liquid separation was possible by combining cyclones in multiple stages. That is, the mist gas-liquid separator section of the present invention comprises two or more stages, preferably two or three stages of cyclones connected in series. In four or more stages, the pressure loss in the cyclone increases and the operation of the entire concentration and purification apparatus becomes difficult, but the increase in effect is small.

The type of each cyclone can be either a simple tangent inlet type or a full-circle spiral inlet type, but a standard cyclone with a simple tangential inlet as shown in FIG. 3 is particularly preferably used. The cyclone design is based on the Chemical Engineering Handbook and Perry's Ha
Any dimensional ratio described in the nd Book may be used. In particular, in FIG.
= 1/4 * Dc to 1/5 * Dc, h = 1/2 * Dc, l = 1/2 * Dc or
Design conditions of 2/5 * Dc, H1 = Dc to 2 * Dc, and H2 = 2 * Dc are preferable. When the cyclone diameter Dc is designed to be 10 m / sec to 150 m / sec, preferably 20 m / sec to 100 m / sec at a cyclone inlet air velocity of 100 Torr, a particularly remarkable effect is obtained.

As the material of the cyclone, aluminum or stainless steel can be used, but aluminum or an aluminum alloy is preferable in order to suppress decomposition of hydrogen peroxide to a small extent. Aluminum and stainless steel can also be used for the material of the rectification column, but aluminum or an aluminum alloy is preferable in order to reduce decomposition of hydrogen peroxide.

When the amount of hydrogen peroxide (equivalent to pure content) entering the evaporator is defined as 100 parts by weight, the amount of hydrogen peroxide extracted in a cyclone and separated as an aqueous solution of hydrogen peroxide is 40 to 75. It is preferable that the amount is by weight. The flow rate of the reflux water is controlled so that the concentration of the concentrated aqueous hydrogen peroxide solution at the bottom of the rectification column becomes 40% by weight to 70% by weight. The temperature at the outlet of the evaporator, i.e. at the inlet of the first stage cyclone, is between 40C and 90C, preferably between 60C and 80C. The operation is performed while controlling the pressure at the inlet of the first cyclone to 50 Torr to 200 Torr, preferably 60 Torr to 150 Torr.

[0012]

According to the present invention, the crude hydrogen peroxide aqueous solution is evaporated by an evaporator, and the generated vapor is separated from the liquid, supplied to the rectification column and concentrated. Part of the aqueous hydrogen peroxide solution was mixed into the rectification column, and the problem of reduced purity of the concentrated purified solution due to organic or inorganic impurities contained in the crude hydrogen peroxide was solved. Supplied.

[0013]

Next, the present invention will be described in detail with reference to examples. The invention is not limited to the figures or embodiments described. Example 1 As shown in FIG. 2, three stages of standard cyclones described in Perry's Hand Book with Dc = 1,240 mm were connected in series. Rectification tower (material: A
l) has a tower diameter of 1,700 mm and is filled with a porcelain filler at a height of 6,000 mm, which is the same as the rectification column described above. A crude aqueous hydrogen peroxide solution containing 32 wt% of hydrogen peroxide, 35 ppm of an evaporation residue, 10 ppm of sodium pyrophosphate decahydrate as a stabilizer and 20 ppm of aminotri (methylenephosphonic acid) was supplied to the evaporator at a flow rate of 5,700 kg / hr. 1600 kg / hr of hydrogen peroxide concentration of 64 wt% from the line below the cyclone and 1,400 kg of high-purity concentrated liquid with hydrogen peroxide concentration of 54 wt% from the bottom of the rectification tower
/ hr. The main operating conditions are shown below. Evaporator outlet: 68-70 ° C, pressure: 90-100 Torr Reflux water: about 1,500 l / hr Cyclone inlet gas velocity was calculated to be about 60 m / s at the first stage from the material balance. The main impurities of the obtained high-purity concentrate are shown below. Na: 10 ppb or less (analyzed by atomic absorption) Evaporation residue: 2 ppm or less (analyzed by JISK1463)

Example 2 A cyclone of Dc = 1,240 mm was installed behind a standard cyclone described in Perry's Hand Book of Dc = 960 mm to form a two-stage cyclone. The rectification tower (material: Al) has a tower diameter of 1,700 mm and is filled with a porcelain filler at a height of 6,000 mm, and is the same as the rectification tower described above. Hydrogen peroxide 32wt%, evaporation residue 35p
pm, 10 ppm of sodium phosphate diacid decahydrate as a stabilizer
And a crude hydrogen peroxide aqueous solution containing 20 ppm of aminotri (methylenephosphonic acid) and fed to the evaporator at a flow rate of 5,700 kg / hr to concentrate, and the hydrogen peroxide concentration was reduced from the line below the cyclone.
A 1,600 kg / hr of a 64 wt% separated liquid and a 1,400 kg / hr of a high purity concentrated liquid having a hydrogen peroxide concentration of 54 wt% were obtained from the bottom of the rectification column. The main operating conditions are shown below. Evaporator outlet: 68 to 70 ° C, pressure is 90 to 100 Torr Reflux water: about 1,500 l / hr Cyclone inlet gas velocity is about 100 m / m at the first stage from material balance
s, the second stage was calculated to be about 60m / s. The main impurities of the obtained high-purity concentrate are shown below. Na: 10 ppb or less (analyzed by atomic absorption) Evaporation residue: 3 ppm (analyzed by JISK1463)

Comparative Example 1 In Example 1, a single-stage standard cyclone described in Perry's Hand Book with Dc = 1,240 mm was used.
l) is a column with a diameter of 1,700mm and a porcelain filler packed at a height of 6,000mm.
%, Evaporation residue 35ppm, as a stabilizer
10 ppm of decahydrate and aminotri (methylene phosphonic acid) 20p
The crude hydrogen peroxide solution containing pm is supplied to the evaporator at a flow rate of 5,700 kg / hr and concentrated, and from the line below the cyclone, the separated liquid with a hydrogen peroxide concentration of 64 wt% is 1,600 kg / hr and the rectification tower From the bottom, 1,400 kg / hr of a high-purity concentrated liquid having a hydrogen peroxide concentration of 54 wt% was obtained. The main operating conditions are shown below. Evaporator outlet: 68-70 ° C, pressure: 90-100 Torr Reflux water: about 1,500 l / hr The gas velocity at the cyclone inlet was calculated to be about 60 m / s from the material balance. The main impurities of the obtained high-purity concentrate are shown below. Na: 70ppb (analyzed by atomic absorption) Evaporation residue: 11ppm (analyzed by JISK1463)

Comparative Example 2 In Example 1, a rectification column (material: A) consisting of only one stage of a standard cyclone described in Perry's Hand Book with Dc = 960 mm
l) is a column with a diameter of 1,700mm and a porcelain filler packed at a height of 6,000mm.
%, Evaporation residue 35ppm, as a stabilizer
10 ppm of decahydrate and aminotri (methylene phosphonic acid) 20p
The crude hydrogen peroxide solution containing pm is supplied to the evaporator at a flow rate of 5,700 kg / hr and concentrated, and from the line below the cyclone, the separated liquid with a hydrogen peroxide concentration of 64 wt% is 1,600 kg / hr and the rectification tower From the bottom, 1,400 kg / hr of a high-purity concentrated liquid having a hydrogen peroxide concentration of 54 wt% was obtained. The main operating conditions are shown below. Evaporator outlet: 68-70 ° C, pressure: 90-100 Torr Reflux water: about 1,500 l / hr Cyclone inlet gas velocity was calculated to be about 100 m / s from the material balance. The main impurities of the obtained high-purity concentrate are shown below. Na: 110ppb (analyzed by atomic absorption) Evaporation residue: 15ppm (analyzed by JISK1463)

[Brief description of the drawings]

FIG. 1 shows a conventional concentration and purification device.

FIG. 2 shows an apparatus for concentrating and purifying hydrogen peroxide according to the present invention.

FIG. 3 shows the structure of a cyclone.

[Explanation of symbols]

 2: Evaporator 4: Gas-liquid separator 6: Rectification tower 8: Condenser 21: Crude hydrogen peroxide supply line 24: Evaporator 26, 28, 30: Cyclone 32: Rectification tower 34: Condenser 35: Reflux water 37 : High-purity hydrogen peroxide extraction line Dc: Cyclone diameter

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-5-140044 (JP, A) JP-T-62-502821 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B01D 45/12 C01B 15/013

Claims (5)

(57) [Claims] 1. A method in which a vapor and a mist generated by evaporating an aqueous solution containing hydrogen peroxide by an evaporator are separated by a gas-liquid separator, and the vapor is supplied to a rectification column for concentration and purification. Is a multi-stage cyclone configured by connecting two or more cyclones. 2. The method according to claim 1, wherein the cyclones are connected in two or three stages. 3. The pressure at the gas-liquid separator inlet is 50-2.
2. The method of claim 1, wherein the pressure is 00 Torr. 4. The method according to claim 1, wherein the inlet airflow velocity of each cyclone of the multistage cyclone is 10 to 150 m / sec. 5. The temperature at the gas-liquid separator inlet is 40-9.
The method of claim 1, wherein the temperature is 0 ° C.