JPH06319939A - Method fort cleaning harmful gas - Google Patents

Abstract

PURPOSE:To remove efficiently a basic gas such as ammonia which is used in a semiconductor manufacturing process and contained in exhaust gas and air etc., by the leakage etc., of a bomb by contacting a gas containing the basic gas with a cleaning agent in which copper salt is deposited on metal oxide having copper oxide and manganese oxide as the main components. CONSTITUTION:A gas containing a basic gas (for example, ammonia) as a harmful component is contacted with a cleaning agent in which a tetravalent copper salt is deposited on metal oxide having a bivalent copper oxide and a tetravalent manganese oxide as the main components to remove the harmful component from the gas. For the bivalent copper salt, one or two kinds of inorganic acids are selected from carbonic acid, silicic acid, nitric acid, sulfuric acid, phosphoric acid, boric acid, chloric acid, perchloric acid, chlorous acid, and hypochlorous acid. As a result, the basic gas such as ammonia and amine can be removed efficiently which is used in a semiconductor manufacturing process and contained in exhaust gas and air etc., by the leakage, etc., of a bomb.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for removing harmful gases, and more particularly to a method for purifying basic harmful gases such as ammonia and amines used in semiconductor manufacturing processes. In recent years, with the development of the semiconductor industry, the optoelectronics industry, and the precision equipment industry, the amount of basic gases such as ammonia and amines used has been increasing. These basic gases are indispensable substances in semiconductor manufacturing processes such as chemical vapor deposition, decorative / protective film manufacturing, and super hard equipment manufacturing, but they are all highly toxic and give off a pungent odor and Harm to the environment. The permissible concentrations of these gases are, for example, 25 ppm of ammonia and 10 ppm of trimethylamine. It is necessary to remove harmful components from the gas containing these harmful and toxic gases before using them in the semiconductor manufacturing process and before releasing them to the atmosphere. There is.

These basic ammonia-based gases are usually put on the market in a gas cylinder having a capacity of about 0.1 to 50 L. In order to prevent the air from directly contaminating the outside air when a gas leaks, the gas cylinder is normally stored in a cylinder container connected to a ventilation duct called a cylinder box, and the gas to the semiconductor process etc. Used by connecting to the supply pipe. Even if the cylinder is stored in the cylinder box, there is no risk of sudden leakage such as emptying of the cylinder in a short time of about 5 to 10 minutes due to an unexpected accident. There is a strong demand for complete measures to deal with such accidents.

[0003]

2. Description of the Related Art As a method for removing a basic gas contained in a gas, there is a wet method in which a scrubber is absorbed and decomposed, and an aqueous solution mainly containing an acidic component is used as an absorbing liquid. Further, in the dry method, there is an example in which activated carbon or an inorganic compound-based porous adsorbent is used.

[0004]

However, the wet method has the drawbacks that the size of the apparatus becomes large, the post-treatment is difficult, and the maintenance cost of the apparatus becomes high. further,
Under the present circumstances, the adsorption efficiency is not necessarily high, and in the case of a high concentration of harmful gas, it cannot be completely treated. Moreover,
It may contain harmful gas other than basic gas at the same time. For example, in the semiconductor industry, since silicon compound gas is also used at the same time, there is a problem that sludge is generated due to generation of oxide crystals. In addition, there is a method of adsorption treatment with activated carbon as a dry method, but not only the detoxifying ability is low, but also in the presence of a combustible gas such as silane, there is a risk of causing a fire. Therefore, the processing speed and processing capacity of the harmful gas are large, and the concentration is relatively low due to an abnormality in the cylinder, etc., but not only in an emergency where a large amount of gas leaks, but also the concentration that is usually emitted from the semiconductor manufacturing process is high. There has been a demand for a purification method which is excellent in removing performance against harmful gases and the like, has no risk of fire, and has no fear of clogging of the purification cylinder with products.

[0005]

Means for Solving the Problems As a result of intensive studies to solve these problems, the present inventors have found that metal oxides containing copper (II) oxide and manganese (IV) oxide as main components are selected. It was found that the use of a purifying agent impregnated with a copper (II) salt is extremely effective in eliminating a basic harmful gas and is highly safe, and has completed the present invention. That is, the present invention is a purifying agent obtained by impregnating a gas containing a basic gas, which is a harmful component, with a metal oxide containing copper (II) oxide and manganese (IV) oxide as main components and a copper (II) salt. And a harmful component is removed from the gas by bringing the gas into contact with the gas. INDUSTRIAL APPLICABILITY The present invention is applicable to harmful gases containing basic gases such as ammonia and dimethylamine, trimethylamine, monomethylamine, hydrazine, dimethylhydrazine and other amines contained in gases such as air, nitrogen and hydrogen.
In particular, the purification method of the present invention can remove a large amount of harmful gas quickly and at room temperature. For example, the basic harmful gas discharged from a semiconductor manufacturing process or the like, or the gas leaks rapidly from a cylinder, etc. With this, excellent effects such as quick purification of air polluted by harmful gas can be obtained.

In the present invention, a copper (II) salt is impregnated with a copper (II) salt of an inorganic acid or an organic acid to a metal oxide containing copper (II) oxide or manganese (IV) oxide as a main component. Examples of the inorganic acid salt include oxo acid salts and halides, and examples of the oxo acid salt include carbonic acid,
Copper (II) salts such as silicic acid, nitric acid, sulfuric acid, phosphoric acid, arsenic acid, boric acid, chloric acid, perchloric acid, chlorous acid and hypochlorous acid, and halides such as copper (II) chloride, Copper (II) bromide, copper (II) iodide and the like can be mentioned. As the organic acid, formic acid, acetic acid, propionic acid, oleic acid, aliphatic monocarboxylic acids such as stearic acid, oxalic acid,
Examples thereof include aliphatic dicarboxylic acids such as adipic acid and sebacic acid, oxyacids such as lactic acid and tartaric acid, aromatics such as benzoic acid and toluic acid, and copper (II) salts of various acids such as naphthenic acid. Among these, copper nitrate, copper sulfate, copper chloride, copper bromide, copper acetate and the like are water-soluble and are preferable in terms of easy handling. Various hydrates are known as copper (II) salts, from anhydrous to polyhydrate, but they have no adverse effect on the ease of handling, the stability in air, and the ability to remove harmful gases. It is generally preferred to use a hydrate, since it does not affect.

Further, in addition to copper (II) oxide and manganese (IV) oxide which are the main components, cobalt (III) oxide, silver (I) (II) oxide, aluminum (III) oxide, and oxides are used as metal oxides. It may be one or a mixture of two or more of silicon (IV). The content of copper (II) oxide and manganese (IV) oxide in the metal oxide is usually 60% by weight or more, preferably 70% by weight or more in total. The ratio of manganese (IV) oxide to copper (II) oxide is usually about 1: 0.8 to 5, preferably about 1: 1.2 to 3. These metal oxide-based compositions can be prepared by mixing the respective components or by various known methods, but since they are commercially available as hopcalite, it is convenient to use them. Hopcalite is 40% by weight of copper (II) oxide and manganese oxide (I).
V) A 60% by weight binary element system is mainly sold on the market, and an oxide of potassium, magnesium, aluminum, silicon, etc. is mixed as an additive at a ratio of about 30% by weight with a copper-manganese system. Therefore, they may be used as they are, or may be used by mixing them with the above-mentioned other metal oxides.

Metal oxides are crushed products, extruded products,
A tablet-molded product or the like, the size of which is about 4 to 20 mesh for a crushed product and 1.5 for an extruded product.
˜4 mmφ × 3 to 20 mm, and if it is a tablet-molded product, it is usually preferably cylindrical and has a size of about 3 to 6 mmφ × 3 to 6 mm.

The amount of the copper (II) salt attached to the metal oxide is not particularly limited and may be selected depending on the type and concentration of the basic gas. For example, 3 to 100 relative to 100 parts by weight of hopcalite. It is about 5 to 50 parts by weight, preferably about 5 to 50 parts by weight. If the amount of copper (II) salt is less than 3 parts by weight, the purification efficiency will be low, while if it exceeds 50 parts by weight, it will not be sufficiently retained by metal oxides such as hopcalite and will be expensive. In the present invention, it is desirable to add free water to the purifying agent in addition to the water of crystallization of copper (II) salt for the purpose of further increasing the efficiency of removing harmful components. The amount of free water retained is usually 1 to 50% by weight, preferably 5 to 30% by weight, based on the total weight of the cleaning agent. To obtain a purifying agent by impregnating a copper (II) salt, for example, copper sulfate is dissolved in warm water, and this is impregnated with a metal oxide, and then 30-100
It can be produced by drying at about 0 ° C. until a predetermined water content is reached. The purifying agent thus obtained has the advantage that it can be used in a semiconductor manufacturing process at the same time as the basic gas and decomposes monosilane mixed in the exhaust gas to render it harmless.

In the present invention, the concentration of the basic harmful gas is usually 1% or less, preferably 1000 ppm or less. Further, the contact temperature between the purifying agent and the gas is about 0 to 90 ° C., which is usually operated at room temperature (10 to 50 ° C.), and heating or cooling is not particularly required. After the contact is initiated, the reaction heat causes a temperature rise depending on the concentration of the harmful gas. The pressure at the time of contact is usually atmospheric pressure, but reduced pressure to 1
It is also possible to operate under pressure such as kg / cm ² G. The gas to be purified in the present invention, such as air, nitrogen and hydrogen, may be in a dry state or a wet state as long as it does not cause dew condensation, but it is generally 30 to 100 which corresponds to a normal atmosphere. % Relative humidity is often used, in which case the free water content in the purifier is 5 to 3
It is preferably about 0% by weight. Further, carbon dioxide in the air or the like is not adversely affected, and the presence of carbon dioxide may rather increase the purification capacity depending on the situation.

There are no particular restrictions on the concentration and flow rate of the basic gas such as ammonia contained in the gas to which the purification method of the present invention is applied, but it is generally desirable to reduce the flow rate as the concentration increases. The concentration of the harmful gas that can be removed is usually 1% or less, but if the flow rate is small, it is possible to treat a basic gas having a higher concentration. The purifying cylinder is designed according to the harmful gas concentration, the amount of gas to be treated, etc., but at a relatively low concentration of the harmful gas concentration of 0.1% or less, the hollow cylinder linear velocity (LV) is 0.5 to. 50 cm / sec,
When the harmful gas concentration is 0.1 to 1%, the LV is 0.05 to
1 at high concentration such as 20 cm / sec and concentration of 1% or more
It is preferable to design in the range of 0 cm / sec or less. Therefore, in the case of toxic gas with a high concentration constantly emitted from the semiconductor manufacturing process, 10 cm / sec or less, and when the toxic gas suddenly leaks from the gas cylinder and is diluted with a large amount of air, etc. LV is 0.5 to 50
cm / sec is a general standard.

The purifying agent is usually packed in a column for purifying harmful gas and used as a fixed bed, but it can also be used as a moving bed or a fluidized bed. Normally, the purifying agent is filled in the purifying cylinder, and the gas containing the ammonia-based basic gas is caused to flow in the purifying cylinder, and the harmful ammonia-based basic gas is removed by bringing the gas into contact with the purifying agent. . In the present invention, the packing density when the cleaning agent is packed in the cleaning column is 1.
It is about 0 to 1.5 g / ml. The cleaning agent is, for example, FIG.
And, it is used by being filled in the purification cylinder 1 as shown in the flow sheet of FIG. When purifying the exhaust gas from the semiconductor manufacturing apparatus 2 as shown in FIG. 1, the exhaust gas is connected to the duct 6 led from the manufacturing apparatus 2 and used. When used for treating leaked gas from a gas cylinder, as shown in FIG. 2, the purifying cylinder 1 has a cylinder box 4 containing a cylinder 3 of harmful gas and a blower for continuously sucking and ventilating air. It is used by interposing a ventilation duct 6 for connecting with 5. The purifying agent generates a large amount of heat when the concentration of the harmful gas exceeds 1%, and thus heat removal means may be required. However,
In the equipment as shown in FIG. 2, a blower having a capacity sufficient to dilute the concentration to 1% or less is usually provided by mixing with a diluting gas such as air or nitrogen even if a rapid leak of harmful gas occurs. ing.

[0013]

【Example】

Examples 1 to 4 Preparation of Purifying Agent 25 to 250 g of copper sulfate pentahydrate is dissolved in 400 to 800 ml of warm water, and 40 wt% of copper (II) oxide is placed in a vat.
%, Manganese (IV) oxide 60 wt% binary hopcalite (manufactured by Nissan Gardler)
It was dried at 100 ° C. to obtain four kinds of purifying agents having different copper sulfate contents and free water contents. A purification test for harmful gas was conducted using each of these four types of purifying agents. A purifying agent of 85 ml was filled in a purifying cylinder made of quartz glass having an inner diameter of 19 mm and a length of 500 mm, and dry nitrogen containing 1% of ammonia was heated at 20 ° C. under atmospheric pressure to 170 ml / min.
It was circulated at a flow rate of (LV = 1.0 cm / sec). A part of the outlet gas of the purification column is sampled, and a gas detection tube (Gastec, detection lower limit 2 ppm) and a gas detector (Bionics Equipment Co., Ltd., model number TG-2400B)
Measured in A), ammonia has an upper limit of allowable concentration (25 pp
The time required to reach m) (effective treatment time) was measured. The results are shown in Table 1.

[0014]

[Table 1] Table 1 Example Copper sulfate Free water Hazardous gas Empty cylinder linear velocity Effective treatment time Content rate Content rate concentration LV (wt%) (wt%) (%) (cm / sec) (min) 1 57 1 1.0 5012 2 10 〃 〃 〃 6950 3 40 8 〃 〃 9005 4 100 9 〃 〃 9996

Examples 5 to 7 Purification tests were conducted in the same manner as in Example 1 except that the same purifying agent as in Example 3 was used and the ammonia concentration and the gas flow rate (LV) were variously changed. The results are shown in Table 2.

[0016]

[Table 2] Table 2 Examples Copper sulphate Free water Hazardous gas Empty cylinder linear velocity Effective treatment time Content rate Content rate concentration LV (wt%) (wt%) (%) (cm / sec) (min) 5 40 8 1.0 10.0 901 6 〃 〃 〃 0.5 18016 7 〃 〃 0.1 10.1 10.0 9012

Examples 8 and 9 Using the same purifying agent as in Example 3, the flow rate (L) of nitrogen containing 1% of trimethylamine in place of ammonia was used.
V) was changed, and a purification test was conducted in the same manner as in Example 1, and the concentration of trimethylamine was the upper limit of allowable concentration (10 ppm).
The time to reach was measured. The results are shown in Table 3.

[0018]

[Table 3] Table 3 Example Copper sulfate Free water Hazardous gas Empty cylinder linear velocity Effective treatment time Content rate Content rate concentration LV (wt%) (wt%) (%) (cm / sec) (min) 8 40 8 1 10.0 805 9 〃 〃 〃 1.0 8753

Examples 10 and 11 In order to examine the effect of harmful gases other than basic gases on the purifying agent, nitrogen containing 1% of monosilane was passed for 100 minutes, 1000 minutes and 5000 minutes at a constant flow rate. ,
In each case, the ability to remove ammonia was measured in the same manner as in Example 1. The results are shown in Table 4.

[0020]

[Table 4] Table 5 Examples Monosilane flow time Effective treatment time (min) (min) 10 100 8997 11 1000 8861

Example 12 Using the same purifying agent as in Example 3, nitrogen containing 1% ammonia and 1% monosilane was circulated at a constant rate, and the removal ability of ammonia and monosilane was measured in the same manner as in Example 1. did. The results are shown in Table 4.

[0022]

[Table 4] Table 4 Example Copper sulfate empty cylinder linear velocity Silane Ammonia content rate LV Effective treatment time Effective treatment time (wt%) (cm / sec) (min) (min) 13 40 1.0 1600 8985

Comparative Example 1 Ammonia removing ability was measured in the same manner as in Example 1 except that the same hopcalite (manufactured by Nissan Gardler) as in Example 1 was used as a purifying agent without copper (II) salt impregnation. The results are shown in Table 5.

[0024]

[Table 5] Table 5 Comparative example Empty cylinder linear velocity Hazardous gas concentration Effective treatment time (cm / sec) (%) (min) 1 1.0 1 18

[0025]

According to the gas purification method of the present invention, ammonia-based basic gases such as ammonia and trimethylamine contained in the gas can be efficiently removed. Regardless of whether the concentration is high or low, harmful gas can be removed efficiently and extremely quickly. Also, even if other harmful gases such as silane coexist, they can be removed at the same time as the basic gas, so that, for example, purification of exhaust gas in the semiconductor manufacturing process or emergency removal such as sudden leakage of harmful gas from a gas cylinder is possible. An excellent effect can be obtained by using it in a harmful device.

[0026]

[Brief description of drawings]

FIG. 1 is a flow sheet showing an example of a method for purifying harmful gas.

FIG. 2 is a flow sheet of a purification method having an aspect different from that of FIG.

[Explanation of symbols]

 1 Purification Cylinder 2 Semiconductor Manufacturing Equipment 3 Gas Cylinder 4 Cylinder Box 5 Blower 6 Duct

Claims (3)

[Claims] 1. A purifying agent obtained by impregnating a gas containing a harmful basic gas with a metal oxide containing copper (II) oxide and manganese (IV) oxide as a main component and a copper (II) salt. A method for purifying noxious gas, which comprises contacting the gas with a gas to remove harmful components from the gas. 2. The basic gas is ammonia, monomethylamine, dimethylamine, trimethylamine, hydrazine,
The method for purifying a harmful gas according to claim 1, which is one kind or two or more kinds selected from dimethylhydrazine. 3. A copper (II) salt selected from the group consisting of carbonic acid, silicic acid, nitric acid, sulfuric acid, phosphoric acid, boric acid, chloric acid, perchloric acid, chlorous acid and hypochlorous acid. The method for purifying toxic gas according to claim 1, wherein there are two or more kinds.