JP5309945B2 - Halogen-based gas scavenger and halogen-based gas scavenging method using the same - Google Patents

Description

The present invention is an etching process in the semiconductor and LCD manufacturing, CVD detoxifies the exhaust gas containing chlorine gas discharged from such (chemical vapor deposition) process, and a cleaning step, detoxifying agents of the chlorine gas and chlorine gas used it It relates to abatement methods.

  Thermal decomposition methods, wet methods, and dry methods are known as methods for detoxifying exhaust gases containing halogen-based gases discharged from etching processes, CVD (chemical vapor deposition) processes, and cleaning processes in semiconductor / liquid crystal manufacturing. . In the thermal decomposition method, the exhaust gas is decomposed by heating or combustion. In the pyrolysis method, there is a problem of using a high temperature in a semiconductor factory that handles a large amount of combustible gas. The pyrolysis gas is treated with water or the like, but wastewater treatment becomes a problem.

  In the wet method, an aqueous alkali solution such as an aqueous caustic soda solution or water is absorbed. When the exhaust gas is absorbed in an alkaline aqueous solution, there are problems such as contamination of the wafer by sodium and solid matter produced by the reaction between the halogen-based gas and the alkaline aqueous solution blocking the exhaust line of the processing apparatus. Moreover, when using water, in order to suppress the amount of waste_water | drain, in many cases, the wash water is circulated and used, There exists a problem in which the said waste gas is not fully wash | cleaned.

  The dry method is a simple method in which a solid detoxifying agent and the exhaust gas are brought into contact with each other, and is widely used as a method that can improve the problems of the thermal decomposition method and the wet method. Many abatement agents that have been proposed so far use a large amount of activated carbon, but activated carbon has a risk of ignition and explosion due to heat generation due to rapid adsorption and reaction of halogen gas, A detoxifying agent and a detoxifying method using a nonflammable zeolite have been proposed. Zeolite has a large number of crystal structures, and the composition and pore size are also diverse.

  For example, Patent Document 1 discloses a method of detoxifying a halogen-based gas by combining alumina and / or zeolite and soda lime. Patent Document 2 describes that a halogen-based gas having an average pore diameter of 9 mm or more is used. Patent Documents 3 and 4 describe a halogen-based gas removal method including a step of contacting a halogen-based gas with a detoxifying agent such as zeolite. MS-5A (CaA-type zeolite) and MS-13X are used as zeolites. (NaX type zeolite) and the like are exemplified. Patent Document 5 describes a method of removing a halogen-based gas by using a granulated product made of a porous body of a solid base, a carbonaceous material, and an inorganic oxide, and examples of zeolite include A-type zeolite. .

Patent Document 6 discloses a faujasite-type zeolite having a SiO ₂ / Al ₂ O ₃ molar ratio of 2.0 to 2.3 containing at least one alkali metal and / or alkaline earth metal as a cation. Halogen-based gas scavengers are exemplified, but in all cases, K cation was 30 mol% or less.

  What has been disclosed so far has not always been sufficient in the halogen gas removal performance.

JP-A-62-289222 (Claim 1) JP-A-6-47233 (Claim 1) JP 2001-338910 A (Claims 16 and 18) JP-A-2004-181300 (claim 1 and description {0012} column) WO2003 / 033115 (Claims 1 to 7 and page 10, line 43) JP 2008-229610 A (Claims 1 to 3 and page 10, line 43)

The present invention provides a detoxifying agent comprising a zeolite capable of detoxifying chlorine gas with higher efficiency than ever, and a method for detoxifying chlorine gas using the same.

As a result of intensive studies to achieve the above object, the present inventor has found a detoxifying agent and a detoxifying method capable of detoxifying chlorine gas safely and more efficiently than a detoxifying agent using a conventional zeolite.

The following describes abatement methods chlorine gas used detoxifying agent chlorine gas and its invention.

Detoxifying agents of the chlorine gas of the present _invention, SiO 2 / _Al 2 _{O 3} molar ratio is 2.0 to 2.3, those comprising a faujasite type zeolite containing more than 50 mol% K cation In particular, the K cation is preferably contained in an amount of 80 mol% or more.

The remaining cation is Na cations.

As the zeolite species of the present pesticide, a faujasite type zeolite having a SiO ₂ / Al ₂ O ₃ molar ratio of 2.0 to 2.3 is used, and in particular, the SiO ₂ / Al ₂ O ₃ molar ratio is In particular, 2.0 to 2.2, more preferably 2.0 to 2.1 is preferable.

The chlorine gas detoxifying agent of the present invention is a faujasite type zeolite having a low SiO ₂ / Al ₂ O ₃ molar ratio as a faujasite type zeolite (usually called LSX (Low Silica X) zeolite). When used, it exhibits a performance improvement far beyond the performance improvement expected from the stoichiometric increase in the cation content.

The chlorine gas abatement agent of the present invention may contain a binder, but the binder component (clay mineral, silica, alumina, etc.) is converted to a zeolite by making it binderless in order to further enhance the abatement capability. In particular, it is preferable to perform modification conversion to zeolite crystals (usually referred to as “binderless”) until the remaining binder becomes 0 to 10 wt% .

  Zeolite powder is a micron-order powder, and is used as a molded body when used in adsorption applications. However, since zeolite powder does not have self-bonding properties, a binder is added during molding. As the binder, clay minerals (kaolin, attapulgite, sepiolite, montmorillonite, etc.), silica, alumina and the like are typically used. Since these binders have extremely low adsorption capacity and the adsorption capacity is reduced by the amount of the binder added, it is preferable to use the detoxifying agent of the present invention by further increasing the adsorption capacity by making the binder component binderless.

The chlorine gas scavenger of the present invention uses a faujasite type zeolite having a low SiO ₂ / Al ₂ O ₃ molar ratio, contains K cation as a cation in an amount of 50 mol% or more, preferably 80 mol% or more , Furthermore, by making the binder component binderless, the abatement performance exceeding the expected increase rate of chlorine gas abatement performance from the expected increase rate of the zeolite component in the abatement agent is exhibited. .

The binder-less binder component can be carried out by converting the binder component of the zeolite molded body molded with a binder such as clay into zeolite by alkali treatment. Zeolite is converted from the binder is faujasite type zeolite valid _SiO 2 / _Al 2 _{O 3} molar ratio abatement of chlorine gas is 2.0 to 2.3 are preferred.

The binder used is not particularly limited as long as it can be converted into a faujasite type zeolite having a SiO ₂ / Al ₂ O ₃ molar ratio of 2.0 to 2.3, but a clay mineral is preferably used. However, kaolin clay is preferred. Kaolin clay is composed of SiO ₂ and Al ₂ O ₃ like zeolite, SiO ₂ / Al ₂ O ₃ molar ratio is 2.0, and SiO ₂ / Al ₂ O ₃ molar ratio is 2.0 to This is because the composition is similar to that of 2.3 faujasite type zeolite.

Conditions such as alkali concentration, SiO ₂ concentration, temperature, reaction time, etc. when making binderless are conditions under which binderlessness is sufficiently advanced and impurities are not generated, and the strength at which the molded body does not become powdered when used. If it is. For example, an alkali concentration of 0.5 to 10 mol / L, particularly 6 to 10 mol / L when converted to LSX zeolite, an SiO ₂ concentration of 0 to 1.5 wt%, a temperature of 70 to 95 ° C., and a reaction time of 3 to 10 hours can be exemplified. .

Next, the chlorine gas removal method using the remover of the present invention will be described.

Abatement process of the present invention, except using the harm-removing agent of the present invention as a detoxifying agent contacting with the chlorine gas can be carried out similarly to the abatement process of chlorine gas by the conventional dry method. For example, when a detoxification tower (adsorption tower) having a chlorine gas inlet at one end and a gas outlet at the other end is filled with the detoxifying agent of the present invention and chlorine gas is introduced from the gas inlet, the book in the detoxification tower Chlorine gas is adsorbed on the detoxifying agent of the invention, and a gas having a chlorine gas concentration below an allowable concentration is released from the gas outlet.

Treatment of the removal agent filling amount, shape and particle diameter of the removal agent of the present invention, removal tower size, chlorine gas flow rate (linear velocity), chlorine gas concentration, removal temperature, removal pressure, etc. The conditions are appropriately selected so that the abatement ability does not decrease. Usually, the detoxifying agent used is a molded body such as a spherical shape or a cylindrical shape, and preferably a spherical shape is used. In the case of a spherical shape, a particle diameter of 0.1 to 5 mm can be used, and in the case of a cylindrical shape, a diameter of about 0.5 to 3 mm and a length of about 1 to 10 mm can be used. If the particle size is extremely small, the pressure loss of the detoxification tower is large and the circulation of chlorine gas becomes difficult. If the particle size is too large, the detoxification efficiency is lowered. The concentration of chlorine gas is adjusted to be in the range of 0.1 to 10% by volume, and the linear velocity is in the range of 0.01 to 10 m / second. The detoxification temperature is not particularly required to be heated and cooled, and is normal temperature (20 to 30 ° C.), and the detoxification pressure may be atmospheric pressure.

The chlorine gas detoxifying agent of the present invention can efficiently detoxify chlorine gas in exhaust gas discharged from etching processes, CVD (chemical vapor deposition) processes and cleaning processes in semiconductor / liquid crystal manufacturing. is there. Since the chlorine gas detoxifying agent of the present invention has higher detoxifying performance than before, the replacement frequency of the detoxifying tower can be reduced.

  Hereinafter, the present invention will be described using examples and comparative examples.

Example 1
A chlorine gas detoxifying agent was prepared using LSX zeolite (a faujasite type zeolite having a SiO ₂ / Al ₂ O ₃ molar ratio of 2.0) as the zeolite powder. LSX zeolite was synthesized as follows.

A reaction vessel was charged with sodium silicate aqueous solution (Na ₂ O = 3.8 wt%, SiO ₂ = 12.6 wt%) 10770 g, water 1330 g, sodium hydroxide (purity 99%) 1310 g, industrial potassium hydroxide aqueous solution (purity 48 %) 3630 g was added and kept at 45 ° C. with stirring at 100 rpm. To the solution, 5390 g of a 40 ° C. sodium aluminate aqueous solution (Na ₂ O = 20.0 wt%, Al ₂ O ₃ = 22.5 wt%) was added. Next, 4.22 g of LSX powder was dispersed in a small amount of water and added. The composition of the slurry after the addition was 3.39Na ₂ O · 1.31K ₂ O · 1.90SiO ₂ · Al ₂ O ₃ · 74.1H ₂ O. The mixture was stirred at 100 rpm and aged at 45 ° C. for 1 hour. After aging, the temperature was raised to 70 ° C. over 1 hour while continuing stirring, and then the stirring was stopped and crystallization was performed at 70 ° C. for 8 hours. The obtained crystals were filtered, washed with pure water, and then dried at 70 ° C. overnight to obtain LSX zeolite. The obtained LSX zeolite was a faujasite type zeolite from X-ray diffraction, and the chemical composition was 0.72Na ₂ O · 0.28K ₂ O · Al ₂ O ₃ · 2.0SiO ₂ .

  After mixing and kneading 20 parts by weight of attapulgite clay as a binder with respect to 100 parts by weight of the obtained LSX zeolite, and finally adding 65 parts by weight of water with respect to 100 parts by weight of LSX zeolite while appropriately adding water, He was sufficiently relaxed. This kneaded product was granulated and formed into beads having a diameter of 1.2 to 2.0 mm and dried at 100 ° C. overnight. Subsequently, after calcination at 600 ° C. for 2 hours under air circulation, the mixture was cooled in the air and humidified so that the water content was 20 to 25%.

The molded body was subjected to K exchange and washed with water. After the molded body was dried, it was subjected to an activation treatment at 530 ° C. for 3 hours under a flow of dry air, and cooled to prevent moisture absorption, thereby obtaining a detoxifying agent of the present invention. The obtained scavenger had a SiO ₂ / Al ₂ O ₃ molar ratio of 2.0, and the cations were K55 mol% and Na 45 mol%.

Chlorine gas removal evaluation was performed using the obtained remover. As the detoxification tower, a gas inlet at the lower end and a gas outlet at the upper end were used, and a stainless steel having an inner diameter of 28 mm, a height of 280 mm, and an internal volume of 172 ml was used. The abatement tower was installed vertically and filled with the abatement agent of the present invention. As the chlorine gas, a gas in which the Cl ₂ concentration was adjusted to 0.5% by volume with N ₂ was used, and the treatment was performed under atmospheric pressure at 25 ° C. and a superficial linear velocity of 0.08 m / sec. The Cl ₂ concentration of the gas flowing out from the gas outlet at the upper end of the detoxification tower is measured using an electrochemical sensor (Dregel Safety Japan, Polytron 7000), and breakthrough occurs when the Cl ₂ concentration reaches 1 ppm. As a result, the amount of adsorption per unit weight of the adsorbent was determined. Table 1 shows the results of the detoxifying ability of the pesticide.

The detoxification ability of Cl ₂ was a detoxification performance far exceeding the rate of increase of cation sites due to the increase in SiO ₂ / Al ₂ O ₃ molar ratio of faujasite type zeolite from 2.5 to 2.0. It was. Furthermore, the ability was higher than the detoxifying agent disclosed in Patent Document 6.

Example 2
A detoxifying agent was prepared in the same manner as in Example 1 except that the composition of the cation was K82 mol% and Na 18 mol%, and the detoxifying ability was evaluated. Table 1 shows the results of the detoxifying ability of the pesticide.

Example 3
A detoxifying agent was prepared in the same manner as in Example 1 except that the cation composition was K99 mol% and Na 1 mol%, and the detoxifying ability was evaluated. Table 1 shows the results of the detoxifying ability of the pesticide.

Example 4
25 parts by weight of kaolin clay and 4 parts by weight of CMC (carboxymethylcellulose) are mixed with 100 parts by weight of the LSX zeolite synthesized in Example 1, and finally 100 parts by weight of LSX powder is added while adding water appropriately. The mixture was adjusted to 75 parts by weight and then kneaded for 1 hour. The kneaded product was molded into a cylindrical shape having a diameter of 1.5 mm, the length was adjusted to 3 to 5 mm, and then dried at 200 ° C. Subsequently, after baking at 600 ° C. for 3 hours under a circulation of dry air, the mixture was cooled in the air and humidified so that the water content was 20 to 25%. The obtained molded body was filled in a column having an inner diameter of 108 mm and a height of 1500 mm to make it binderless. In the binder-less process, 30 liters of a solution having a NaOH concentration of 2.2 mol / L and a SiO ₂ concentration of 1.0 wt% was used, and the reaction was performed at a temperature of 90 ° C. for 6 hours while circulating the solution. Clay) was converted to faujasite type zeolite. Next, the column was thoroughly washed with water while being packed in the column. Thereafter, K exchange was performed to obtain K65 mol% and Na 35 mol%. The scavenger obtained had a SiO ₂ / Al ₂ O ₃ molar ratio of 2.1. Activation treatment and detoxification evaluation were performed in the same manner as in Example 1. Table 1 shows the results of the detoxifying ability of the pesticide.

Comparative Example 1
LSX zeolite was synthesized in the same manner as in Example 1. After mixing and kneading 20 parts by weight of sepiolite clay as a binder with respect to 100 parts by weight of the obtained LSX zeolite, finally adding 65 parts by weight of water to 100 parts by weight of LSX zeolite while adding water appropriately, He was sufficiently relaxed. This kneaded product was granulated and formed into beads having a diameter of 1.2 to 2.0 mm and dried at 100 ° C. overnight. Subsequently, after calcination at 600 ° C. for 2 hours under air circulation, the mixture was cooled in the air and humidified so that the water content was 20 to 25%.

The shaped body was exchanged with Na and washed with water. After the molded body was dried, it was subjected to an activation treatment at 530 ° C. for 3 hours under a flow of dry air, and cooled to prevent moisture absorption, thereby obtaining a detoxifying agent of the present invention. The obtained detoxifying agent had a SiO ₂ / Al ₂ O ₃ molar ratio of 2.0 and cations of Na 98 mol% and K ₂ mol%. The detoxification evaluation is carried out in the same manner as in Example 1, and the results of the detoxifying ability of the detoxifying agent are shown in Table 1.

Comparative Example 2
An LSX zeolite molded body in which only the binder-less process was performed in the same manner as in Example 4 was prepared. The cation was 89 mol% Na and 11 mol% K. Activation treatment and chlorine gas removal evaluation were carried out in the same manner as in Example 1. Table 1 shows the results of the detoxifying ability of the pesticide.

Comparative Example 3
The same operation as in Example 2 was carried out using Tosoh F-9 powder (SiO ₂ / Al ₂ O ₃ molar ratio 2.5, faujasite type zeolite whose cation is Na) as the zeolite powder, and binderless There was no conversion. The chlorine gas removal evaluation was carried out in the same manner as in Example 1. Table 1 shows the results of the detoxifying ability of the pesticide.

Claims (4)

A SiO ₂ / _Al 2 _{O 3} molar ratio of 2.0 to 2.3, containing 50 mol% or more of K cations as cations, comprising the faujasite type zeolite remaining cations are Na cation chlorine Gas scavenger. The chlorine gas abatement agent according to claim 1 , wherein K is contained as a cation in an amount of 80 mol% or more, and the remaining cation is a Na cation . The chlorine gas scavenger according to claim 1 or 2 , wherein the binder content is 0 to 10 wt%. A method for removing chlorine gas, comprising contacting chlorine gas with the chlorine gas remover according to any one of claims 1 to 3 .