JP2010137174A - Detoxifying agent for halogen gas and method for detoxifying halogen gas using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a detoxifying agent composed of a zeolite, which detoxifies halogen gas with high efficiency, and to provide a method for detoxifying halogen gas using the same. <P>SOLUTION: A faujasite type zeolite having a SiO<SB>2</SB>/Al<SB>2</SB>O<SB>3</SB>mole ratio of 2.0-2.3 and containing not less than 30 mol% of at least a K cation is used as the detoxifying agent. The detoxifying agent preferably contains not less than 50 mol%, and more preferably not less than 80 mol% of the K cation. A binder is preferably used zeolitized when used for molding. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a halogen-based gas detoxifying agent that detoxifies exhaust gas containing a halogen-based gas discharged from an etching process, a CVD (chemical vapor deposition) process, a cleaning process, etc. in semiconductor / liquid crystal manufacturing, and a halogen using the same. The present invention relates to a system gas removal method.

  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 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 clogging 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 for treatment, and is often employed 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 a halogen-based gas with higher efficiency than ever, and a method for detoxifying a halogen-based 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 a halogen-based gas safely and more efficiently than a detoxifying agent using a conventional zeolite.

  Hereinafter, the halogen-based gas scavenger of the present invention and the halogen-based gas scavenging method using the same will be described.

Detoxifying agents of halogen-containing gas of the present _invention, SiO 2 / _Al 2 _{O 3} molar ratio is 2.0 to 2.3, contains a faujasite-type zeolite containing K cations in excess of at least 30 mol% In particular, the K cation is preferably contained in an amount of 50 mol% or more, and more preferably 80 mol% or more.

  The remaining cations are not particularly limited, but for example, Na cations may be used.

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 halogen-based gas scavenger 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} Is used, the performance improvement far exceeds that expected from the stoichiometric increase in the cation content.

  The halogen-based 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 modify and convert to zeolite crystals until the remaining binder is 0 to 10% (usually referred to as “binderless”).

  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 halogen-based gas scavenger of the present invention uses a faujasite type zeolite having a low SiO ₂ / Al ₂ O ₃ molar ratio, and contains at least K cation as a cation exceeding 30 mol% (preferably 50 mol% or more, Furthermore, by making the binder component binder-free, the increase rate of the halogen gas detoxification performance expected from the expected increase rate of the zeolite component in the detoxifying agent can be increased. Excess detoxification performance is demonstrated.

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 effective _SiO 2 / _Al 2 _{O 3} molar ratio abatement of halogen-containing gas is preferably faujasite zeolite of 2.0 to 2.3.

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 halogen gas removal method using the remover of the present invention will be described.

  The detoxifying method of the present invention can be carried out in the same manner as the detoxifying method for halogen-based gas by the conventional dry method, except that the detoxifying agent of the present invention is used as a detoxifying agent to be brought into contact with the halogen-based gas. For example, when a detoxification tower (adsorption tower) having a halogen-based gas inlet at one end and a gas outlet at the other end is filled with the detoxifying agent of the present invention and the halogen-based gas is introduced from the gas inlet, The halogen-based gas is adsorbed by the detoxifying agent of the present invention, and a gas having a halogen-based gas concentration below an allowable concentration is released from the gas outlet.

  Packing amount of the detoxifying agent of the present invention, shape and particle size of the detoxifying agent, size of the detoxifying tower, halogen gas flow rate (linear velocity), concentration of halogen gas, detoxifying temperature, detoxifying pressure, etc. The treatment 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. When the particle size is extremely small, the pressure loss of the detoxification tower is large and the circulation of the halogen-based gas becomes difficult. When the particle size is too large, the detoxification efficiency is lowered. The concentration of the halogen-based 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.

As the halogen-based gas in the present invention, halogen (F ₂ , Cl ₂ , Br ₂ , I ₂ ), hydrogen halide (HF, HCl, HBr, HI), silicon halide (SiF ₄ , SiCl ₄ , SiBr ₄ ) Boron halide (BCl ₃ ), tungsten halide (WF ₆ , WCl ₆ ), carbonyl halide (COF ₂ , COCl ₂ ), and halogen oxide (OF ₂ ).

The halogen-based gas scavenger of the present invention is a halogen, hydrogen halide, silicon halide, halogen in exhaust gas discharged from an etching process, a CVD (chemical vapor deposition) process and a cleaning process in semiconductor / liquid crystal manufacturing. It is possible to efficiently remove halogen-based gases such as boron halide, tungsten halide, carbonyl halide, and halogen oxide. Among them, it is possible to perform detoxification with very high efficiency against halogen gas, particularly Cl ₂ . Since the halogen-based gas detoxifying agent of the present invention has a 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 halogen-based gas scavenger 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%.

Using the obtained detoxifying agent, the detoxification of the halogen-based gas was performed. 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 halogen-based 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 at 25 ° C. and a superficial linear velocity of 0.08 m / sec under atmospheric pressure. 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 flow 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. The same operation as in Example 1 was performed for the activation treatment and the halogen gas removal evaluation. 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 detoxification evaluation of the halogen-based gas was performed in the same manner as in Example 1. Table 1 shows the results of the detoxifying ability of the pesticide.

Claims (6)

SiO ₂ / _Al 2 _{O 3} molar ratio is 2.0 to 2.3, halogen-containing gas harm-removing agent comprising a faujasite type zeolite containing K cations in excess of at least 30 mol% as a cation. The halogen-based gas scavenger according to claim 1, wherein K is contained as a cation in an amount of 50 mol% or more. 3. The halogen-based gas scavenger according to claim 1, comprising K as a cation in an amount of 80 mol% or more. The halogen-based gas scavenger according to any one of claims 1 to 3, wherein the binder content is 0 to 10 wt%. A method for removing a halogen-based gas, comprising contacting the halogen-based gas with the halogen-based gas detoxifying agent according to any one of claims 1 to 4. 6. The method for removing halogen-based gas according to claim 5, wherein the halogen-based gas is halogen (F ₂ , Cl ₂ , Br ₂ , I ₂ ).