JP2002316019A - Method for removing halogen gas - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for removing halogen gas which suppresses the firing of adsorbent, is high in treating ability of halogen gases and reduces the odor of the used adsorbent and the generation of solid waste. SOLUTION: Metals or metallic compounds of one kind or more selected from a group consisting of palladium, iron, nickel, cobalt, manganese and copper, and hydrogen carbonate of the averaged grain size of primary particles 10-500 μm are granulated, is brought into contact with the halogen gases and removes the same.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for removing a halogen-based gas containing at least one selected from the group consisting of Cl ₂ , Br ₂ and I ₂ (hereinafter referred to as the present halogen-based gas). The present invention relates to a method for removing a halogen-based gas from a dry etching exhaust gas or the like containing a system gas.

[0002]

2. Description of the Related Art Conventionally, as a method for treating dry etching exhaust gas containing the halogen-based gas or exhaust gas of a CVD (chemical vapor deposition) chamber, activated carbon or the like has been used for the purpose of miniaturizing equipment and simplifying operation. A dry treatment method using an adsorbent or the like is employed. However, there were problems such as ignition due to heat of adsorption during gas adsorption, odor of used adsorbent, generation of solid waste, and the like.

[0003]

SUMMARY OF THE INVENTION In view of the above problems, the present invention suppresses ignition of an adsorbent, has a high processing capacity for halogen-based gas, and reduces the odor of used adsorbent and the generation of solid waste. And a method for removing a halogen-based gas.

[0004]

The present invention provides palladium,
A substance containing one or more elements selected from the group consisting of iron, nickel, cobalt, manganese and copper (hereinafter referred to as the present metal-containing substance), and an average particle diameter of primary particles of 10 to 50
Provided is a method for removing a halogen-based gas, in which 0 μm bicarbonate powder is mixed and granulated, and the obtained granules are contacted with the halogen-based gas to remove the halogen-based gas.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, sodium bicarbonate, potassium bicarbonate and the like can be used as bicarbonate. In particular, sodium bicarbonate is preferred because it is industrially suitable because it can be obtained in large quantities and at low cost, and because it has low hygroscopicity and is easy to use in producing and storing granules. On the other hand, when it is desired to prevent sodium from being mixed into the exhaust gas or the like after the removal treatment, potassium hydrogen carbonate is preferable.

In the present invention, the bicarbonate powder and the metal-containing substance are formed into granules. The granulated material preferably contains 70% by mass or more of hydrogencarbonate. If the content of bicarbonate in the granulated product is less than 70% by mass, the gas treatment capacity as a halogen-based gas remover decreases, and the frequency of replacement of the remover-filled layer is undesirably increased. The content of bicarbonate is particularly preferably 80% by mass or more. Here, the present metal-containing substance may be a simple metal, or a metal compound or a mixture thereof.

In the present invention, the reactivity of hydrogencarbonate can be improved by adding the present metal-containing substance to the granulated product, and the effect can be maintained for a longer time. As a method for including the present metal-containing substance in the granulated product, the granulated product is mixed with a hydrogen carbonate and then granulated. The content of the present metal-containing substance in the granulated product is preferably 0.001 to 10% by mass. When the content is less than 0.001% by mass, the effect of improving the reactivity of the granulated product is not obtained, and it is not preferable. When the content is more than 10% by mass, the reactivity is not further improved and unnecessarily. In addition to using the present metal-containing substance, the content of hydrogencarbonate decreases, and the capacity for removing halogen-based gas decreases, which is not preferable. The content is particularly preferably 0.005 to 5% by mass. In addition, as a material contained in the granulated material, an adsorbent other than bicarbonate, such as activated carbon, a binder, and the like are included.

In the present invention, the bicarbonate powder having an average primary particle diameter of 10 to 500 μm is used. When the average particle diameter of the primary particles is less than 10 μm, the fluidity is poor, and handling such as handling becomes difficult.
If it is more than m, it is technically difficult to produce a granulated product and the cost becomes high, which is not preferable. The primary particles are a single crystal of hydrogen carbonate, and the average particle size is an average particle size on a weight basis.

In the present invention, the average particle diameter of the bicarbonate powder and the granulated product of the present metal-containing substance is 0.5 to 20 m.
m. When the average particle diameter of the granulated material is 0.5 to 20 mm, a conventionally used packed tower or the like can be used in treating a halogen-based gas. When the average particle diameter of the granulated material is less than 0.5 mm, the pressure loss when the halogen-based gas or the gas to be treated containing the same passes through a packed bed or the like increases, and when the average particle diameter exceeds 20 mm. In addition, the contact area between the gas to be treated and the granulated material is reduced, and the performance of removing the exhaust gas is reduced. The average particle size of the granulated product is particularly preferably 0.5 to 10 mm.

In the present invention, the average particle size of the granulated product is measured by the following method. Laminate sieves with openings in the range corresponding to the particle size of the granulated material, install a bottom plate at the bottom, pour the granulated material from above, shake with a shaker, and then use each standard sieve. The mass of the upper residue is measured, and the total of the mass of the residue on the sieve with respect to each aperture value is shown in a line graph. The difference between the openings of the upper and lower sieves depends on the particle size of the granulated material, but is not less than 0.1%.
Preferably, a pitch of 5 mm is used.

In the present invention, the granulated product is obtained by a compression molding method,
It can be obtained by various methods such as a rolling granulation method and a stirring granulation method. Here, the compression molding method is industrially simple because the process is simple, and it is possible to obtain a granulated material without using a binder. It is particularly preferable because granules can be obtained.

As a method for obtaining granules, for example, there is a method in which a compression molding machine is used to dry-mold, then coarsely pulverized and sieved. Further, there is also a method in which a wet compression molding machine is used to form a water-soluble binder, followed by drying.

In the present invention, when the bicarbonate powder and the granulated material of the present metal-containing substance are used by being filled in a packed bed to treat a halogen-based gas, if the strength is low, the And the pressure loss when passing through the packed bed may increase. For this reason, the strength of the granulated material is increased.

As a method for evaluating the strength of the granulated product in the present invention, hardness is mentioned. Here, the hardness is a force required to compress and break one of the granulated particles by applying a load vertically from above.

The method for evaluating hardness in the present invention is performed on particles having a uniform particle size by classifying the granulated particles according to the average particle size. For example, the average particle diameter is 1.5 mm or more and 2.0 m
For granules less than m, sieve using a sieve with a mesh of 1.5 mm and a sieve with a mesh of 2.0 mm, collecting 20 particles above and below 1.5 mm sieve, The hardness of each particle is measured, and the average value is adopted as an evaluation standard of the particle strength.

As for the hardness of the granulated product of the present invention, in the case of a granulated product having an average particle size of 0.5 mm or more and less than 1.0 mm, the average hardness of the granulated product having a particle size of 0.5 mm or more and less than 1.0 mm is determined. 1N or more, average particle size 1.0 mm or more and 1.5 mm
In the case of a granulated material of less than 1.0 mm or more and 1.5 mm in particle diameter
The average hardness of the granulated material having a particle diameter of less than 4N is not less than 4N, and the average hardness of the granulated material having a particle diameter of not less than 1.5mm and less than 2.0mm is 1.5mm or more and less than 2.0mm. 1
In the case of granules having an average particle diameter of 2.0 mm or more and 20 mm or more, the average hardness of the granules having a particle diameter of 2.0 mm or more is preferably 30 N or more.

In the present invention, the present halogen-based gas is removed. For example, a dry etching exhaust gas or the like containing a halogen-based gas is treated to remove the halogen-based gas in the exhaust gas. In addition, for example, BCl ₃ , CCl ₄ , S
iCl ₄ , HCl, COCl ₂ , F ₂ , SiF ₄ , HF, C
It may contain a simple halogen or a halogen compound such as OF ₂ , NF ₃ , WF ₆ , ClF ₃ and HBr.

In the present invention, the temperature of the gas to be treated is 0 ° C.
It is preferable that the temperature is in the range of 100 to 100 ° C. because the removal treatment can be performed efficiently. If the temperature of the gas to be treated is lower than 0 ° C., the reaction rate is undesirably reduced. When the temperature is 100 ° C. or lower, the equipment such as the packed tower does not need to be made of an expensive heat-resistant material or structure, and the operation and the equipment can be simplified.

In the present invention, the hydrogen carbonate reacts with a halogen alone or a halogen compound to form a water-soluble salt. Since the bicarbonate itself is water-soluble, most of the granules other than the present metal-containing substance can be dissolved in water after being used for removing halogen-based gas in exhaust gas. The present metal-containing substance can be recovered by dissolving the granulated substance in water and then filtering. Further, as described later, for example, when a bicarbonate and activated carbon are used in combination, solid waste can be reduced.

Since hydrogen carbonate reacts with a simple halogen or a halogen compound to form a water-soluble salt, the simple halogen or the halogen compound is not desorbed and no odor is generated as in the case of activated carbon adsorption. Therefore, the work of replacing the packed layer and the like can be easily performed. In addition, there is no danger of ignition because the bicarbonate itself has a fire extinguishing property.

In the present invention, by adding the present metal-containing substance to the granulated product, the reactivity between the bicarbonate and the halogen is improved, and even when the same amount of the bicarbonate is used, a larger amount of the halogen is used. Can be used for system gases. Although the mechanism is not clear, the decomposition of hypohalite generated when the substance containing the above element reacts with Cl ₂ , Br ₂ or I ₂ contained in the halogen-based gas and the hydrogen carbonate. It is presumed to promote. Normally, when Cl ₂ , Br ₂ or I ₂ contained in a halogen-based gas reacts with a hydrogen carbonate, a hypohalite is generated according to the following reaction formula 1. It is known that the generated hypohalite is decomposed into sodium halide and oxygen in accordance with the reaction formula 2. However, when the hypohalite remains without being decomposed, it is considered that the reaction between the hydrogen carbonate and the halogen hardly proceeds. It is considered that by mixing the metal or the metal compound of the present invention, the decomposition reaction of the hypohalite is promoted, and the efficiency of removing the halogen-based gas is improved.

NaHCO ₃ + X ₂ → NaXO + CO ₂ + HX Formula 1. (X = Cl, Br, I) NaXO → NaX + ／ O ₂ ...

In the present invention, it is also preferable that the granulated material is packed in a vessel such as a packed tower together with activated carbon and brought into contact with a halogen-based gas to remove the halogen-based gas. This method not only can increase the removal amount of halogen alone, but also can reduce the generation of odor from activated carbon, as compared with the case where activated carbon is used alone. Specifically, the bicarbonate and the activated carbon are used in a layered manner in a container such as a packed tower.

[0024]

EXAMPLES In the following examples, the hardness and the average particle size were measured by the following methods. The hardness was measured using a Kiya type digital hardness meter KHT-20 manufactured by Fujiwara Seisakusho. Since the hardness varies depending on the size of the particles, the particles were sieved to make the particle diameter uniform.

The average particle size was measured by the following method. 100 g of a powder sample was weighed with a standard sieve (inner diameter: 200 mm,
Wire mesh stainless steel) with aperture of 3.35mm,
2.80 mm, 2.36 mm, 2.00 mm, 1.70
mm, 1.00 mm, put on the bottom plate at the bottom and pour it on, using a low tap shaker type shaker made by Iida Seisakusho (frequency: 60 Hz, 290 rotations / min, 165 strokes / min) After shaking for 10 minutes, the mass of each standard sieve residue was measured, and the total of the sieve residue mass with respect to each aperture value was shown in a line graph. The particles when the total sieve residue mass was 50% The diameter was taken as the average particle diameter.

[Example 1] Powder of sodium bicarbonate for food additives having an average primary particle diameter of 91 µm (manufactured by Asahi Glass Co., Ltd.)
299.97 kg and 0.03 kg of palladium oxide were mixed, and a roll press-type compression molding machine (trade name: roller compactor WP type, manufactured by Turbo Kogyo Co., Ltd., roll outer diameter 230 m)
m, roll length 80 mm) using a linear pressure of 36.8 kN /
cm and compression molded to obtain a flake-like molded product of sodium bicarbonate powder. The obtained flake-shaped compact was crushed with a flake breaker, and the mesh of a rotary sizing machine was set to 4.75 mm to allow the whole to pass through. Then, a rotary sieving machine (Turbo Kogyo Co., trade name: turbo Screener TS
Using a mold) to remove particles having a particle diameter of 4.0 mm or more and particles having a particle diameter of 1.0 mm or less, so that the average particle diameter is 2.3 m.
m of sodium bicarbonate powder was obtained.

The particle strength of the granulated product was measured by the hardness measurement method described above. That is, the obtained granules having an average particle diameter of 2.3 mm were squeezed into 0.5 mm, 1.0 mm, 1.5 mm
mm, 2.0 mm, sieved with a 2.5 mm mesh sieve,
When the hardness of each particle size was measured 20 and the average value was obtained,
The average hardness of the particles between 0.5-1.0 mm is 3N;
11N for 0-1.5mm, 18 for 1.5-2.0mm
N, 2.0 mm or more was 58N.

Next, the bottom is made of an air-permeable sintered plate with an inner diameter of 300 m.
m, 1300 mm long, in a stainless steel filled container with a fluororesin lining
0 kg was charged. As a gas to be treated, a gas having a composition ratio of BCl ₃ : 20% by volume, Cl ₂ : 60% by volume, and argon: 20% by volume in a standard state at a flow rate of 200 cm ³ / min.
The mixture was poured from the bottom of the filled container at 5 ° C. under normal pressure. When the gas flowing out from the top of the filling container was analyzed, BC
l ₃ is not detected, Cl ₂ concentration was at most 0.1 vol ppm.

After a lapse of 362 hours from the start of the treatment, the Cl ₂ concentration in the effluent gas began to rise above 0.1 ppm by volume. When the filler was taken out, there was no powdering of the granulated particles or generation of odor. Further, when this filler was dissolved in water, it was almost dissolved, and solid waste could be reduced. Further, expensive palladium oxide could be recovered by filtering the solution.

Example 2 A test was conducted in the same manner as in Example 1 except that 299.7 kg of sodium hydrogencarbonate was used and 0.03 kg of palladium oxide was changed to 0.3 kg of nickel oxide. When the effluent gas was analyzed in the same manner as in Example 1, no BCl ₃ was detected, and the Cl ₂ concentration was 0.1 volume p.
pm or less.

After a lapse of 356 hours from the start of the treatment, the Cl ₂ concentration in the effluent gas began to rise above 0.1 ppm by volume. When the filler was taken out, there was no powdering of the granulated particles or generation of odor. Further, when this filler was dissolved in water, it was almost dissolved, and solid waste could be reduced. Further, nickel oxide could be recovered by filtering the solution.

Example 3 A test was conducted in the same manner as in Example 1 except that the amounts of sodium hydrogencarbonate and metal oxide were changed to 297 kg and 3 kg. As for metal oxides, iron oxide, cobalt oxide, manganese dioxide, and copper oxide were tested. When the outflow gas was analyzed in the same manner as in Example 1, no BCl ₃ was detected in any of the gases, and the Cl ₂ concentration was 0.1 ppm by volume or less.

From the start of the treatment, after 351 hours of iron oxide, 349 hours of cobalt oxide, 355 hours of manganese dioxide, 352 hours of copper oxide, Cl
_{2 The} concentration began to rise above 0.1 ppm by volume. When the filler was taken out, there was no powdering of the granulated particles or generation of odor. Further, when this filler was dissolved in water, it was almost dissolved, and solid waste could be reduced. Further, any metal oxide could be recovered by filtering the solution.

Example 4 (Comparative Example) A test was conducted in the same manner as in Example 1 except that the granulated product of Example 1 was changed to only sodium bicarbonate. When the effluent gas was analyzed in the same manner as in Example 1,
No BCl ₃ was detected and the Cl ₂ concentration was less than 0.1 ppm by volume.

After a lapse of 309 hours from the start of the treatment, the Cl ₂ concentration in the effluent gas began to rise above 0.1 ppm by volume. When the filler was taken out, there was no powdering of the granulated particles or generation of odor. Further, when this filler was dissolved in water, it was almost dissolved, and solid waste could be reduced.

Example 5 A granulated product of a mixture of sodium bicarbonate powder and palladium oxide obtained in the same manner as in Example 1 (20 k)
g and 20 kg of activated carbon were filled in the same filling container in the same manner as in Example 1. As the gas to be treated, the composition ratio in the standard state is BCl ₃ : 20 vol%, CCl ₄ : 0.6 vol%, C
l ₂ : 41.1% by volume, SiCl ₄ : 0.6% by volume, HC
1: 4.8% by volume, COCl ₂ : 0.6% by volume, F ₂ :
2.7 vol%, SiF _4: 0.6 by volume%, HF: 4.8
Vol%, COF _2: 0.6 vol%, NF _3: 0.8 by volume%, WF _6: 0.6 by volume%, ClF _3: 0.6 by volume%, H
Br: 4.8 vol%, argon: except for using 20.0% by volume of the gas, in the same manner as in Example 1, was analyzed effluent gas, Cl ₂ concentration below 0.1 vol ppm, other BCl ₃ , CCl ₄ , SiCl ₄ , H other than argon
Cl, COCl ₂ , F ₂ , SiF ₄ , HF, COF ₂ , NF
₃ , WF ₆ , ClF ₃ , HBr, etc. were not detected.

After a lapse of 300 hours from the start of the treatment, the Cl ₂ concentration in the effluent gas began to rise exceeding 0.1 ppm by volume. When the filler was taken out, there was no powdering of the granulated particles or generation of odor. When the granulated material was dissolved in water, 90% by mass or more was dissolved.

Example 6 (Comparative Example) A test was conducted in the same manner as in Example 5 except that the granulated product was changed to only sodium bicarbonate. When the effluent gas was analyzed in the same manner as in Example 5, the Cl ₂ concentration was 0.1 vol ppm or less, and BCl ₃ , CCl ₄ , SiCl ₄ , HCl, C
OCl ₂ , F ₂ , SiF ₄ , HF, COF ₂ , NF ₃ , W
F ₆ , ClF ₃ , HBr, etc. were not detected.

After a lapse of 270 hours from the start of the treatment, the Cl ₂ concentration in the effluent gas began to rise beyond 0.1 ppm by volume. When the filler was taken out, there was no powdering of the granulated particles or generation of odor. When the granulated material was dissolved in water, 90% by mass or more was dissolved.

[0040]

Industrial Applicability According to the present invention, as a remover capable of adsorbing a halogen alone or a halogen compound, a granulated product which is not powdered at the time of use, has a higher removal ability, and generates less odor can be obtained. Further, the granulated product of the present invention can be applied as it is to a conventional packed tower using activated carbon.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Hachiro Hirano, Inventor Asahi Glass Co., Ltd. 1-12-1 Yurakucho, Chiyoda-ku, Tokyo No. Asahi Glass Co., Ltd. F term (reference) 4D002 AA18 AA19 AA21 AA22 AA23 AA24 AA25 BA03 BA04 CA07 DA02 DA03 DA11 DA16 DA21 DA22 DA23 DA24 DA25 DA41 EA06 EA07 GA01 GB08 GB12 GB20 HA01 4D048 AA11 AB03 BA35X BAX BAX BAX BAX BAX BB01 EA04 4G066 AA26B AA26D AA27B AA27D AA28B AA28D AA43B BA09 BA20 BA35 CA31 CA32 DA02 FA02 FA26 FA37

Claims (5)

[Claims] 1. A substance containing at least one element selected from the group consisting of palladium, iron, nickel, cobalt, manganese and copper, and an average particle diameter of primary particles of 10 to 500 μm.
The mixture is granulated by mixing the bicarbonate powder of the above, and the obtained granule is brought into contact with a halogen-based gas containing at least one selected from the group consisting of Cl ₂ , Br ₂ and I ₂ to form a halogen-based gas. A method for removing a halogen-based gas that removes a gas. 2. The granulated product according to claim 1, wherein the average particle size is 0.5 to 20 mm.
And having an average hardness defined below.
3. The method for removing a halogen-based gas described in 1. above. In the case of granules having an average particle size of 0.5 mm or more and less than 1.0 mm, the average hardness of the granules having a particle size of 0.5 mm or more and less than 1.0 mm is 1 N or more, and the average particle size is 1.0 mm or more. In the case of granules having a particle size of less than 5 mm, the average hardness of the granules having a particle size of 1.0 mm or more and less than 1.5 mm is 4 N or more, and in the case of a granule having an average particle size of 1.5 mm or more and less than 2.0 mm, The average hardness of the granules having a particle diameter of 1.5 mm or more and less than 2.0 mm is 10 N or more, and in the case of the granules having an average particle diameter of 2.0 mm or more and 20 mm, the average of the granules having a particle diameter of 2.0 mm or more is average. Hardness is 30N or more. 3. The method according to claim 1, wherein the hydrogen carbonate is sodium hydrogen carbonate. 4. The method according to claim 3, wherein the granulated material contains 70% by mass or more of sodium hydrogen carbonate. 5. The method for removing a halogen-based gas according to claim 1, wherein said granulated material is filled in a container together with activated carbon and brought into contact with said halogen-based gas to remove said halogen-based gas.