JP2001232152A - Decomposition treating method of fluorine-containing compound, catalyst and decomposition treating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently decompose a fluorine-containing compound such as CF4, C2F6 containing only fluorine as halogen. SOLUTION: Fluorine in a gas flow containing the fluorine-containing compound containing only fluorine as halogen is converted to hydrogen fluoride by allowing the gas flow to contact with a catalyst consisting of Al and Ni, Al and Zn, or Al and Ti in the presence of steam at about 200-800 deg.C. As a result, the fluorine-containing compound containing only fluorine as halogen is efficiently decomposed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to CF ₄ , C ₂ F ₆ ,
The present invention relates to a method and a catalyst for efficiently decomposing a compound containing fluorine as a halogen, such as SF ₆ and NF ₃ , at a low temperature, and a decomposition apparatus.

[0002]

2. Description of the Related Art Fluorine compound gases containing only fluorine as halogen, such as CF ₄ , C ₂ F ₆ , SF ₆ and NF _3, are used in large quantities in semiconductor etching agents, semiconductor cleaning agents and the like. However, these substances have been found to cause global warming when released into the atmosphere.

Gases such as CF ₄ , C ₂ F ₆ , SF ₆ and NF ₃ contain a large amount of fluorine (F) as a molecular constituent. Fluorine has the highest electronegativity of all elements and forms a very chemically stable substance. Especially CF
₄ , C ₂ F _{6 and the} like are substances having strong intramolecular forces and poor reactivity. Due to this property, heating to a high temperature is necessary to decompose by combustion or the like, and a large amount of energy is consumed. Further, in the decomposition reaction at a high temperature, the rate of corrosion of the device material by the generated gas such as hydrogen fluoride is high, and at present, there is no appropriate decomposition treatment method.

[0004] As a decomposition treatment method, a combustion technique at a high temperature is currently being proposed. However, in this method, since a combustible gas such as propane is used, a large amount of CO ₂ and NOx which is a harmful substance are generated by combustion. In addition, there is a danger of explosion because flammable gas such as propane is used. Further, since the fuel is burned at about 1000 ° C., the furnace wall is damaged by corrosive gas generated by the decomposition of the halogen compound, the frequency of maintenance increases, and the operating cost increases. Therefore, there is a need for a technology that can be decomposed at lower temperatures and without generating harmful substances.

Various patents have been filed for the catalyst for decomposing a halogen compound, but there are few reports that a halogen compound containing only fluorine as a halogen, which is the target gas of the present invention, was decomposed. JP-A-3-66388
The publication describes hydrolysis of a halogen compound by a catalyst containing titania, but describes that the compound does not exhibit decomposition performance with respect to CF ₄ containing only fluorine as a halogen. Also, Chem. Lett. (1989) pp. 19
Okazaki et al. Reported that Fe ₂ O ₃
An attempt was made to hydrolyze CFC-14 (CF ₄ ) using activated carbon, but did not. Regarding the decomposition of a fluorine compound containing only fluorine as halogen, an example using a decomposing agent composed of a hydrogen fluoride-treated inorganic oxide is reported in JP-A-7-116466.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a CF
₄ , a decomposition method for efficiently decomposing a fluorine compound containing only fluorine as a halogen, such as C ₂ F ₆ , SF ₆ , NF _3, etc. at a low temperature; a decomposition catalyst having a high decomposition rate and a long catalyst life; A processing device is provided.

[0007]

Means for Solving the Problems The present inventors have proposed CF ₄ ,
Compounds containing only fluorine as a halogen, such as C ₂ F ₆ , SF ₆ , NF _3, etc., can be decomposed at low temperature and with high efficiency, and the apparatus is hardly corroded by corrosive gas in the decomposition gas. As a result of studying the decomposition method in detail, the present invention has been achieved.

That is, a gas stream containing only fluorine as a halogen and containing the fluorine as a compound of an element selected from carbon, sulfur and nitrogen is mixed with a catalyst containing Al in the presence of water vapor for about 200 hours. A method of converting the fluorine compound in a gas stream to hydrogen fluoride by contacting at ~ 800 ° C to hydrolyze the fluorine compound was found.

A halogen compound containing only fluorine as a halogen, such as CF ₄ or C ₂ F ₆ which is a target gas, is a substance having a strong intramolecular force due to the high electronegativity of fluorine and a poor reactivity. Hardly decomposes in reaction with oxygen. That is, a high decomposition rate can be obtained only by adding H ₂ O.

The fluorine compound to be used in the present invention is a halogen compound containing only fluorine as halogen. The components of the compound include fluorine, carbon, oxygen,
Sulfur, nitrogen and the like; examples of the compound include CF ₄ ,
CHF ₃ , CH ₂ F ₂ , CH ₃ F, C ₂ F ₆ , C ₂ HF ₅ , C _{2
H 2 F 4, C 2 H} 3 F 3, C 2 H 4 F 2, C 2 H 5 F, C 3 F 8, C
H ₃ is _{OCF 2 CF 3, C 4 F} 8, C 5 F 8, SF 6, NF 3 and the like.

In the fluorine compound decomposition treatment method of the present invention, a catalyst containing Al is used. Al is used in the form of an oxide. Al can be used alone,
In addition, Zn, Ni, Ti, Fe, Sn, Pt, C
It can be used in combination with at least one of o, Zr, Ce, and Si. Further, S can be added to these catalysts to increase the decomposition activity of the catalyst.

What is required for the catalyst performance is to have a high decomposition rate and a long catalyst life. As a result of examining the catalysts exhibiting these performances in detail, it has been found that high decomposition performance can be obtained even with Al ₂ O ₃ alone depending on the raw material used.

Al, Zn, Ni, Ti, Fe, Sn,
By using a catalyst comprising at least one of Pt, Co, Zr, Ce, and Si, the decomposition rate can be increased as compared with the case where Al is used alone. In these catalysts, Al exists in the form of Al ₂ O ₃ or a composite oxide with the added metal component. Zn, Ni, T
i, Fe, Sn, Co, Zr, Ce, and Si exist in the form of oxides or composite oxides with Al. In these catalysts, Al: M (= Zn, Ni, Ti, Fe, Sn,
It is preferable that the atomic ratio of Al (at least one of Co, Zr, Ce, and Si) is 50 to 99 mol% and M is 50 to 1 mol%. Alternatively, the catalyst comprising Al and Pt preferably contains Pt in an amount of 0.1 to 2% by weight.
By setting the amount of the additional component other than Al within the above range, a high decomposition rate can be obtained.

To obtain a long catalyst life, Al ₂ O ₃
It is effective to suppress the crystallization of NiAl ₂ O ₄ and ZnAl ₂ O ₄ containing Ni, Zn and the like.
It is desirable to convert the added metal component and Al into a complex oxide. As a method of improving the catalyst performance, there is a method of adding S to the catalyst. As a method for adding S, a method such as using a sulfate at the time of preparing the catalyst or using sulfuric acid can be applied. S in the catalyst exists in the form of SO ₄ ions or the like, and functions to enhance the acidity of the catalyst. The amount of S is preferably from 0.1 to 20% by weight.

In the decomposition method according to the present invention, CF ₄ , C ₂
Oxygen in the gas stream containing fluorine compounds such as F ₆ may be added. It can be used for the oxidation reaction of CO and the like in the decomposition gas.

The following are typical reactions of the decomposition reaction of the fluorine compound.

CF ₄ + 2H ₂ O → CO ₂ + 4HF (Formula 1) C ₂ F ₆ + 3H ₂ O → CO + CO ₂ + 6HF (Formula 2) CHF ₃ + H ₂ O → CO + 3HF (Formula 3) (Formula 2) and Although CO is generated in the reaction of (Equation 3), since the catalyst of the present invention also has CO oxidation performance, CO can be converted to CO ₂ if oxygen is present.

The amount of steam to be added must be adjusted so that hydrogen molecules at least equivalent to the F number in the fluorine compound to be treated are present. As a result, fluorine in the compound can be converted into hydrogen fluoride, and a form that can be easily post-treated can be obtained.

The reaction temperature for hydrolyzing the fluorine compound is as follows:
About 200-800 ° C is preferred. The reaction temperature when treating a fluorine compound composed of at least carbon, fluorine and hydrogen is preferably about 500 to 800 ° C. When used at higher temperatures, a high decomposition rate can be obtained, but the catalyst deteriorates quickly. In addition, corrosion of the device material is likely to progress.

In contacting a gas stream containing only fluorine as a halogen and a compound of the fluorine with an element selected from carbon, sulfur and nitrogen with the catalyst, the content of the fluorine compound in the gas stream is reduced to 0%. It is preferably 0.1 to 10 vol%, and more preferably 0.1 to 3 vol%. The space velocity is preferably from 100 per hour to 10,000 per hour, more preferably from 100 per hour to 3,000 per hour.
Hourly. The space velocity (h ^-1 ) is determined by the reaction gas flow rate (ml /
h) / catalyst amount (ml).

In the fluorine compound decomposition treatment method according to the present invention, hydrogen fluoride, carbon dioxide and the like are generated as decomposition products. In addition, sulfur oxides such as SO ₂ and SO ₃ and nitrogen oxides such as NO and NO ₂ may be generated. In order to remove these decomposition products, it is preferable to wash with an alkaline solution or with water. The method of washing with water is preferable as a method of removing hydrogen fluoride while suppressing corrosion of the apparatus. However, in the case of washing with water, it is desirable that the water containing hydrogen fluoride is subsequently neutralized with an alkali. As the alkali, a common alkali reagent such as an aqueous solution of calcium hydroxide or sodium hydroxide or a slurry solution can be used.

As the Al raw material for preparing the catalyst of the present invention, γ-alumina, a mixture of γ-alumina and δ-alumina, and the like can be used. In particular, those using boehmite as an Al raw material and forming an oxide by firing show high decomposition activity.

The raw materials of various metal components for preparing the catalyst of the present invention include nitrates, sulfates, ammonium salts,
Chloride or the like can be used. Nickel nitrate or nickel sulfate can be used as the Ni raw material. These hydrates can also be used. As Ti raw material,
Titanium sulfate, titania sol and the like can be used.

As the method for producing the catalyst of the present invention, any of a precipitation method, an impregnation method, a kneading method and the like used in the production of ordinary catalysts can be used.

The catalyst according to the present invention can be used as it is in the form of granules, honeycombs or the like.
As the molding method, any method such as an extrusion molding method, a tablet molding method, and a tumbling granulation method can be adopted according to the purpose. Further, it can be used after being coated on a honeycomb or plate made of ceramics or metal.

The reactor used for carrying out the treatment method of the present invention may be of a usual fixed bed, moving bed or fluidized bed type, but a corrosive gas such as HF is generated as a decomposition product gas. Therefore, the reactor should be made of a material that is not easily damaged by these corrosive gases.

The processing apparatus used for carrying out the processing method of the present invention is, in addition to the above-mentioned reactor, means for adjusting the concentration of the fluorine compound in the gas stream, for example, nitrogen or air or A means for supplying oxygen, a means for heating at least one of the gas stream and the catalyst in order to contact the catalyst at a temperature of 200 to 800 ° C., and adding steam or water to the gas stream to decompose the fluorine compound Means for cleaning the decomposition product produced by contacting the gas stream with the catalyst packed in the reactor with water and / or an aqueous alkaline solution to remove a part of carbon dioxide in the decomposition product and SO ₂ An exhaust gas cleaning tank is provided for removing a part of sulfur oxides such as SO ₃ and SO ₃ , a part of nitrogen oxides such as NO and NO ₂ , and hydrogen fluoride. Carbon monoxide in the decomposition product that was not removed after the exhaust gas cleaning tank,
It is further preferable to provide a means for adsorbing sulfur oxides and nitrogen oxides with an adsorbent or the like.

The method for treating a fluorine compound-containing gas of the present invention can be applied to an existing semiconductor factory. Since semiconductor factories generally have exhaust gas treatment equipment for acid component gases,
By utilizing this and installing only the catalyst of the present invention in an exhaust gas line of a fluorine compound such as CF ₄ and adding steam to heat, the fluorine compound can be decomposed.

Further, the whole or a part of the apparatus of the present invention is loaded on a truck or the like and moved to a place where the discarded fluorine compound cylinder is stored, and the contained fluorine compound is extracted and directly treated. You can also. Also,
A circulation pump for circulating the cleaning liquid in the exhaust gas cleaning tank and an exhaust gas adsorption tank for adsorbing carbon monoxide and the like in the exhaust gas may be simultaneously mounted. Further, a generator or the like may be mounted.

According to the method for decomposing a fluorine compound of the present invention, the fluorine compound can be decomposed at a low temperature, and the operating cost can be reduced.

When a fluorine compound-containing gas is treated, corrosion of equipment materials due to acid components such as HF generated by decomposition becomes a problem. According to the present invention, however, the corrosion rate is low because the temperature used is low. It is small and can reduce the maintenance frequency of the device.

The method for decomposing a fluorine compound according to the present invention comprises:
The apparatus includes a catalytic reaction step of decomposing a fluorine compound and an exhaust gas cleaning step of neutralizing and removing an acid component in a decomposition product gas, so that the apparatus can be miniaturized.

Since the decomposition of the fluorine compound is caused by the reaction with water vapor, the safety as a decomposition treatment method is high, and there is no danger of explosion as in the case of using a combustible gas.

[0034]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail with reference to examples. The present invention is not limited to only these examples.

FIG. 1 shows an example of a halogen compound decomposition process when used in a semiconductor etching process.

In the etching step, a fluorine compound 1 such as CF ₄ is put in an etching furnace which is decompressed, and is excited with plasma for 20 minutes to react with a semiconductor. Thereafter, the inside of the chamber was replaced with N ₂ 2, the concentration of the halogen compound was diluted to several percent, and the chamber was discharged from the etching furnace at about 10 l / min.

Air 3 was added to the exhaust gas to dilute halogen compounds such as CF ₄ . At this time, nitrogen may be added for dilution. Further, nitrogen and oxygen may be added for dilution. The reaction gas 5 obtained by adding steam to the diluted gas by the water adding device 4 is sent to a decomposition step. The decomposition step is performed using a reactor filled with a catalyst. The concentration of the halogen compound in the reaction gas is about 0.5 to 1%. In the decomposition step, the reaction gas 5 is supplied at a space velocity of 1,000 per hour (space velocity (h ^-1 ) = reaction gas flow rate (ml / h) / catalyst amount (m
l) a catalyst comprising Al under the conditions of
Contact at 0 ° C. In this case, the reaction gas may be heated, or the catalyst may be heated by an electric furnace or the like. The decomposition gas 6 is sent to an exhaust gas cleaning step. In the exhaust gas cleaning step, water 7 is sprayed on the decomposition gas 6 and the exhaust gas 8 from which the acid components in the decomposition gas have been removed is discharged out of the system. Acidic wastewater 9 containing acidic gas is treated by existing wastewater treatment facilities at a semiconductor factory. The decomposition rate of halogen compounds such as CF ₄ is determined by using FID (Flame Ionization)
Detector) Gas Chromatograph, TCD (Therm
alConductivity Detector) It is analyzed using gas chromatograph, and it is determined by material balance at inlet and outlet.

FIG. 10 shows an example of the processing apparatus of the present invention. The fluorine compound gas from the etching step is sprayed with water at the inlet spray 10 to remove impurities such as SiF _{4 in} the gas. The gas and the water 7 purified by the air 3 and the ion exchange resin 11 are heated by a heater 13 in a preheater 12. Reactor 1
Reference numeral 5 denotes a catalyst filled with Al. Further, a cooling chamber 17 having a water spray means 16 and a water spray means 18 are provided downstream of the reactor 15, and an exhaust gas cleaning tank 20 containing a filler 19 is provided. The exhaust gas 8 is drawn by a blower 21, and the acidic wastewater 9 is drawn by a pump 22. The water containing hydrogen fluoride in the exhaust gas cleaning tank can be subjected to an ion exchange treatment and reused as a pure water raw material.

Example 1 In this example, the activity of various fluorine compound decomposition catalysts was examined.

Air was added to C ₂ F ₆ gas having a purity of 99% or more to dilute it. Steam was further added to this dilution gas. Pure water was supplied to the upper part of the reaction tube at a rate of about 0.2 ml / min using a micro tube pump to vaporize the water. The C ₂ F ₆ concentration in the reaction gas was about 0.5%. The reaction gas was brought into contact with the catalyst heated to a predetermined temperature from the outside of the reaction tube by an electric furnace at a space velocity of 2,000 per hour.

The reaction tube is an Inconel reaction tube having an inner diameter of 32 mm, having a catalyst layer at the center of the reaction tube, and having an outer diameter of 3 mm inside.
It has a thermocouple protection tube made of Inconel. The decomposition product gas that passed through the catalyst layer was bubbled into a calcium fluoride solution and released outside the system. The decomposition rate of C ₂ F ₆ is F
It was determined by the following equation using an ID gas chromatograph and a TCD gas chromatograph.

[0042]

(Equation 1)

The preparation method of each catalyst subjected to the test under the above conditions is shown below.

Catalyst 1: Commercially available boehmite powder at 120 ° C.
For 2 hours. 200 g of the dried powder is fired at 300 ° C. for 0.5 hours, and the firing temperature is increased to 700 ° C.
Fired for hours. Put the obtained powder in a mold, 500kgf
/ Cm ^{2 at} a pressure of compression molding. The molded product was pulverized and sieved to give a test having a particle size of 0.5-1 mm. The completed catalyst consists of Al ₂ O ₃ .

Catalyst 2: commercial boehmite powder at 120 ° C.
For 1 hour. To 200 g of this dry powder, an aqueous solution in which 85.38 g of zinc nitrate hexahydrate was dissolved was added and kneaded. After kneading, dry at 250-300 ° C. for about 2 hours.
Baking was performed at 00 ° C. for 2 hours. The fired product was pulverized and sieved to give a 0.5-1 mm particle size for the test. The catalyst composition after completion was Al: Zn = 91: 9 (mol%) in atomic ratio. This catalyst uses Zn oxide in addition to Al oxide and Zn oxide.
Contains a composite oxide of Al ₂ O ₄ .

Catalyst 3; commercially available boehmite at 120 ° C.
Dried for hours. To 200 g of this dry powder, an aqueous solution in which 50.99 g of nickel sulfate hexahydrate was dissolved was added and kneaded. After kneading, dry at 250-300 ° C. for about 2 hours.
Baking was performed at 00 ° C. for 2 hours. The fired product was pulverized and sieved to give a 0.5-1 mm particle size for the test. The catalyst composition after completion was Al: Ni = 91: 9 (mol%) in atomic ratio. This catalyst is composed of Al oxide, Ni oxide, NiAl ₂
Composite oxides O ₄ and an S oxide.

Catalyst 4: commercial boehmite powder at 120 ° C.
For 1 hour. To 300 g of the dried powder, an aqueous solution in which 125.04 g of nickel nitrate hexahydrate was dissolved was added and kneaded. After kneading, the mixture was dried at 250 to 300 ° C. for about 2 hours and calcined at 700 ° C. for 2 hours. The fired product was pulverized and sieved to give a 0.5-1 mm particle size for the test. The catalyst composition after completion has an atomic ratio of Al: Ni = 91: 9 (mol%).
Met. This catalyst comprises Al oxide, Ni oxide and N
Contains a composite oxide of iAl ₂ O ₄ .

Catalyst 5: Commercially available boehmite powder at 120 ° C.
For 1 hour. 300 g of this dry powder and 354.4 g of a 30% titanium sulfate solution were kneaded while adding about 300 g of pure water. After kneading, the mixture was dried at 250 to 300 ° C for about 5 hours and baked at 700 ° C for 2 hours. The fired product was pulverized and sieved to give a 0.5-1 mm particle size for the test. The catalyst composition after completion was Al: Ti = 91: 9 (mol%) in atomic ratio.

Catalyst 6: Commercial boehmite powder at 120 ° C.
For 1 hour. To 200 g of the dried powder, 9 g of iron nitrate was added.
An aqueous solution in which 115.95 g of hydrate was dissolved was added and kneaded. After kneading, dry at 250-300 ° C. for about 2 hours.
Baking was performed at 00 ° C. for 2 hours. The fired product was pulverized and sieved to give a 0.5-1 mm particle size for the test. The catalyst composition after completion was Al: Fe = 91: 9 (mol%) in atomic ratio.

Catalyst 7: Commercially available boehmite powder at 120 ° C.
For 1 hour. To 200 g of the dried powder, an aqueous solution in which 95.43 g of stannic chloride was dissolved was added and kneaded. After kneading, drying at 250-300 ° C. for about 2 hours,
It was baked at 700 ° C. for 2 hours. The fired product was pulverized and sieved to give a 0.5-1 mm particle size for the test. The catalyst composition after completion was Al: Sn = 91: 9 (mol%) in atomic ratio.

Catalyst 8: Commercial boehmite powder at 120 ° C.
For 1 hour. A dinitrodiammine Pt (II) nitric acid solution (Pt concentration 4.5 wt.
%) And an aqueous solution obtained by diluting 22.2 g with 200 ml of pure water was added and kneaded. After kneading, the mixture was dried at 250 to 300 ° C. for about 2 hours and calcined at 700 ° C. for 2 hours. The fired product was pulverized and sieved to give a 0.5-1 mm particle size for the test. The completed catalyst had a Pt of 0.68 with respect to 100% by weight of Al ₂ O _3.
% By weight.

Catalyst 9: Commercially available boehmite powder at 120 ° C.
For 1 hour. To 300 g of this dry powder, an aqueous solution in which 125.87 g of cobalt nitrate hexahydrate was dissolved was added and kneaded. After kneading, the mixture was dried at 250 to 300 ° C. for about 2 hours and calcined at 700 ° C. for 2 hours. The fired product was pulverized and sieved to give a 0.5-1 mm particle size for the test. The catalyst composition after completion has an atomic ratio of Al: Co = 91: 9 (mol%).
Met.

Catalyst 10: Commercial boehmite powder was mixed with 120
Dried for 1 hour at ° C. To 200 g of the dried powder, an aqueous solution in which 76.70 g of zirconyl nitrate dihydrate was added and kneaded. After kneading, the mixture was dried at 250 to 300 ° C. for about 2 hours and calcined at 700 ° C. for 2 hours. The fired product was pulverized and sieved to give a 0.5-1 mm particle size for the test. The catalyst composition after completion has an atomic ratio of Al: Zr = 91: 9 (mol%).
Met.

Catalyst 11: Commercially available boehmite powder was mixed with 120
Dried for 1 hour at ° C. An aqueous solution in which 124.62 g of cerium nitrate hexahydrate was dissolved was added to 200 g of the dried powder and kneaded. After kneading, the mixture was dried at 250 to 300 ° C. for about 2 hours and calcined at 700 ° C. for 2 hours. The fired product was pulverized and sieved to give a 0.5-1 mm particle size for the test. The catalyst composition after completion is Al: Ce = 91: 9 (mol%) in atomic ratio.
Met.

Catalyst 12: Commercially available boehmite powder was mixed with 120
Dried for 1 hour at ° C. To 300 g of this dry powder, 20 w
An aqueous solution in which 129.19 g of t% silica sol was dissolved was added and kneaded. After kneading, the mixture was dried at 250 to 300 ° C. for about 2 hours and calcined at 700 ° C. for 2 hours. The fired product was pulverized and sieved to give a 0.5-1 mm particle size for the test. The catalyst composition after completion is Al: Si = 91: 9 (mol%) in atomic ratio.
Met.

FIG. 2 shows the test results of the catalysts 1 to 12 at a reaction temperature of 700 ° C. Catalyst consisting of Al and Zn and A
The decomposition activity of the catalyst consisting of 1 and Ni is extremely high. Next, the catalyst composed of Al and Ti has a high decomposition activity.
It is considered that the effect of S is that catalyst 3 has higher activity than catalyst 4.

(Example 2) In this example, using the same Al raw material and Ni raw material as the catalyst 4 of Example 1, a catalyst was prepared in which the composition of Al and Ni was changed, and the decomposition activity of C ₂ F ₆ was prepared. It is the result of having investigated.

Catalyst 4-1: Commercial boehmite powder was added to 12
Dry at 0 ° C. for 1 hour. To 200 g of this dry powder, an aqueous solution in which 8.52 g of nickel nitrate hexahydrate was dissolved was added and kneaded. After kneading, the mixture was dried at 250 to 300 ° C. for about 2 hours and calcined at 700 ° C. for 2 hours. The fired product was pulverized and sieved to a particle size of 0.5-1 mm. The catalyst composition after completion was Al: Ni = 99: 1 (mol%) in atomic ratio.

Catalyst 4-2: Commercially available boehmite powder was added to 12
Dry at 0 ° C. for 1 hour. An aqueous solution in which 66.59 g of nickel nitrate hexahydrate was dissolved was added to 300 g of the dried powder and kneaded. After kneading, the mixture was dried at 250 to 300 ° C. for about 2 hours and calcined at 700 ° C. for 2 hours. The fired product was pulverized and sieved to a particle size of 0.5-1 mm. The catalyst composition after completion was Al: Ni = 95: 5 (mol%) in atomic ratio.

Catalyst 4-3: Commercially available boehmite powder was added to 12
Dry at 0 ° C. for 1 hour. To 200 g of this dry powder, an aqueous solution in which 210.82 g of nickel nitrate hexahydrate was dissolved was added and kneaded. After kneading, the mixture was dried at 250 to 300 ° C. for about 2 hours and calcined at 700 ° C. for 2 hours. The fired product was pulverized and sieved to a particle size of 0.5-1 mm. The catalyst composition after completion was Al: Ni = 80: 20 (mol%) in atomic ratio.

Catalyst 4-4: Commercially available boehmite powder was added to 12
Dry at 0 ° C. for 1 hour. An aqueous solution in which 361.16 g of nickel nitrate hexahydrate was dissolved was added to 200 g of the dried powder and kneaded. After kneading, the mixture was dried at 250 to 300 ° C. for about 2 hours and calcined at 700 ° C. for 2 hours. The fired product was pulverized and sieved to a particle size of 0.5-1 mm. The catalyst composition after completion was Al: Ni = 70: 30 (mol%) in atomic ratio.

Catalyst 4-5: Commercially available boehmite powder was
Dry at 0 ° C. for 1 hour. 562.1 g of nickel nitrate hexahydrate was mixed with 200 g of the dried powder, and kneaded while adding water. After kneading, the mixture was dried at 250 to 300 ° C. for about 2 hours and calcined at 700 ° C. for 2 hours. The fired product was pulverized and sieved to a particle size of 0.5-1 mm. The catalyst composition after completion was Al: Ni = 60: 40 (mol%) in atomic ratio.

The activity of the catalysts 4 and 4-1 to 4-5 is set at a C ₂ F ₆ concentration of 2%, and the amount of pure water to be supplied is about 0.5.
The test was conducted in the same manner as in Example 1 except that the flow rate was 4 ml / min. FIG. 3 shows the decomposition rate 6 hours after the start of the test. Ni /
The activity is highest when the mole% of (Ni + Al) is 20-30 mole%, and then the activity is high when it is 5-40 mole%.

Example 3 In this example, a catalyst was prepared by changing the composition of Al and Zn using the same Al raw material and Zn raw material as the catalyst 2 of Example 1, and the activity was examined. .

Catalyst 2-1: Commercially available boehmite powder was added to 12
Dry at 0 ° C. for 1 hour. To 200 g of this dry powder, an aqueous solution in which 215.68 g of zinc nitrate hexahydrate was dissolved was added and kneaded. After kneading, the mixture was dried at 250 to 300 ° C. for about 2 hours and calcined at 700 ° C. for 2 hours. The fired product was pulverized and sieved to a particle size of 0.5-1 mm. The catalyst composition after completion was Al: Zn = 80: 20 (mol%) in atomic ratio.

Catalyst 2-2: Commercially available boehmite powder was mixed with 12
Dry at 0 ° C. for 1 hour. To 200 g of the dried powder, an aqueous solution in which 369.48 g of zinc nitrate hexahydrate was added was kneaded. After kneading, the mixture was dried at 250 to 300 ° C. for about 2 hours and calcined at 700 ° C. for 2 hours. The fired product was pulverized and sieved to a particle size of 0.5-1 mm. The catalyst composition after completion was Al: Zn = 70: 30 (mol%) in atomic ratio.

Catalyst 2-3: 12 parts of commercially available boehmite powder
Dry at 0 ° C. for 1 hour. To 126.65 g of this dry powder, an aqueous solution in which 96.39 g of zinc nitrate hexahydrate was dissolved was added.
Kneaded. After kneading, the mixture was dried at 250 to 300 ° C. for about 2 hours and calcined at 700 ° C. for 2 hours. The fired product was pulverized and sieved to a particle size of 0.5-1 mm. The catalyst composition after completion was Al: Zn = 85: 15 (mol%) in atomic ratio.

The activities of the catalysts 2 and 2-1 to 2-3 are set at a C ₂ F ₆ concentration of 2%, and the amount of pure water to be supplied is about 0.5%.
The test was conducted in the same manner as in Example 1 except that the flow rate was 4 ml / min. FIG. 4 shows the decomposition rate 6 hours after the start of the test. Ni /
The activity is highest when the mol% of (Ni + Al) is 10-30 mol%.

(Embodiment 4) In this embodiment, CF ₄ , CH
This is a result of performing decomposition of F ₃ and C ₂ F ₆ at different reaction temperatures. The test conditions were the same as in Example 1 except that the space velocity was 1,000 per hour, and the halogen compound was diluted with nitrogen instead of air. The catalyst used was Catalyst 4-3 in Example 2. The results of the test at each reaction temperature are shown in FIG. The catalyst composed of Al and Ni has a high decomposition activity even for CHF ₃ and CF ₄ . It has high activity against these fluorine compounds even at temperatures as low as about 600 ° C.
For F _3, CHF ₃ concentration in the reaction gas is the case of 0.1%, was decomposed 300 ° C. But 35%.

Example 5 This example is a result of examining the effect of water vapor on the decomposition of C ₂ F ₆ . The test conditions are
Same as Example 1 except that the space velocity was set to 1,000 every hour. The catalyst used was the catalyst 4 in Example 1, and the reaction temperature was 700 ° C. In the test, steam was supplied until 2 hours after the start of the reaction, and then the supply of steam was stopped. Five hours later, steam supply was started again. FIG. 6 shows the results of the test. It became clear that the decomposition rate was increased when steam was added, and that the decomposition of C ₂ F ₆ was due to hydrolysis.

(Embodiment 6) This embodiment is a result of decomposition of SF ₆ and C ₃ F ₈ using a catalyst 4-3 comprising Al and Ni. Test conditions of SF ₆ is used having a purity of 99% or more of the SF ₆ gas, a space velocity of 1,000 per hour, SF ₆
Was diluted with nitrogen instead of air. The test conditions for C ₃ F ₈ are the same as in Example 1.
The test results are shown in FIG. SF in the reaction gas at the reaction tube inlet
_The amount of SF _{6 and the} amount of SF _{6 in} the decomposed gas after passing through the alkali absorption tank were measured by a TCD gas chromatograph, and the decomposition rate was determined by the following equation.
_{6 The} decomposition rate was 99% or more. In the decomposition test of C ₃ F ₈ , a high conversion was obtained at a reaction temperature of 700 ° C. or higher.

[0072]

(Equation 2)

Example 7 This example is a result of the decomposition of NF ₃ using the catalyst 4-3 composed of Al and Ni. The test conditions were the same as in Example 6 except that NF ₃ gas having a purity of 99% or more was used. The reaction temperature was set to 700 ° C. The NF ₃ amount of decomposition gas after NF ₃ amount and the alkaline absorption tank passage of the reaction gas in the reaction tube inlet was measured by TCD gas chromatography, the results of obtaining the decomposition rate by the following equation,
The decomposition rate was 99% or more. FIG. 8 shows the decomposition rate at 700 ° C. or less. A decomposition rate of 99.9% was obtained even at 400 ° C.

[0074]

(Equation 3)

Example 8 Al and Zn are represented by atomic ratio of Al:
Using a catalyst containing Zn = 85: 15 (mol%), CF
₄ , C ₄ F ₈ and CHF ₃ were decomposed.

[0076] decomposition of CF _4, the purity of 99% or more of CF ₄
This was done by adding air to the gas to dilute it, adding steam, and contacting it with the catalyst at a predetermined reaction temperature.
The space velocity is 1,000 per hour.

The CF ₄ concentration in the reaction gas is about 0.5%. The flow rate of steam was adjusted so as to be about 50 times that of CF ₄ gas.

The decomposition of CHF ₃ and C ₄ H ₈ was carried out in the same manner.

FIG. 9 shows the test results. The catalyst composed of Al and Zn exhibits high decomposition activity even for CHF ₃ and CF ₄ . It has been clarified that C ₄ F ₈ exhibits high decomposition activity at temperatures around 700 ° C. or other temperatures.

[0080]

According to the present invention, a halogen compound containing only fluorine as halogen, such as CF ₄ , C ₂ F _6, etc., can be efficiently decomposed.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a processing process according to a first embodiment of the present invention.

FIG. 2 is a diagram showing the performance of each catalyst of the present invention.

FIG. 3 is a view showing the C ₂ F ₆ decomposition performance of the Al—Ni catalyst of the present invention.

FIG. 4 is a view showing the C ₂ F ₆ decomposition activity of the Al—Zn catalyst of the present invention.

FIG. 5 shows C ₂ F ₆ , CHF ₃ ,
It is a diagram showing a degradation activity of CF _4.

FIG. 6 is a diagram showing the effect of water vapor on the C ₂ F ₆ decomposition of the Al—Ni catalyst of the present invention.

FIG. 7 is a graph showing SF ₆ and C ₃ F ₈ decomposition activity of the Al—Ni catalyst of the present invention.

FIG. 8 is a graph showing the NF ₃ decomposition activity of the Al—Ni catalyst of the present invention.

FIG. 9 shows CF ₄ , C ₄ F ₈ , C of the Al—Zn catalyst of the present invention.
It is a diagram showing a degradation activity of HF _3.

FIG. 10 is a schematic configuration diagram of a decomposition processing apparatus according to an embodiment of the present invention.

[Explanation of symbols]

Fluorine compounds such as _{1 ... CF 4, 2 ... N} 2, 3 ... air,
4 water addition device, 5 reaction gas, 6 decomposition gas, 7 water
8 ... exhaust gas, 9 ... acid wastewater, 10 ... inlet spray, 11
... Ion exchange resin, 12 ... Preheater, 13 ... Heater, 1
4 ... catalyst, 15 ... reactor, 16, 18 ... spray means,
17: cooling chamber, 19: filler, 20: exhaust gas cleaning tank, 2
1 ... blower, 22 ... pump.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) B01J 23/10 B01J 23/14 A 23/14 23/42 A 23/42 C01B 7/19 A 23/745 17/45 G 23/75 21/083 23/755 B01D 53/36 G C01B 7/19 B01J 23/74 301A 17/45 311A 21/083 321A (72) Inventor Ken Yasuda 7-chome, Omika-cho, Hitachi City, Ibaraki Prefecture No. 1-1 Inside Hitachi, Ltd.Hitachi Research Laboratory (72) Inventor Toshio Yamashita 7-1-1, Omika-cho, Hitachi City, Ibaraki Prefecture Inside Hitachi, Ltd.Hitachi Research Laboratory Co., Ltd. (72) Inventor Shigeru Shozuhata Hitachi, Ibaraki Prefecture 7-1-1, Omikacho Hitachi Research Laboratories Hitachi Research Laboratory, Ltd. (72) Inventor Shin Tamada 3-1-1 Sachimachi, Hitachi-shi, Ibaraki Pref. Hitachi, Ltd. Hitachi Plant Hitachi Plant (72) Inventor Kazuyoshi Ko Hitachi City, Ibaraki Prefecture Saiwaicho Third Street No. 1 No. 1 stock company Hitachi, Ltd. Hitachi in the factory

Claims (15)

[Claims] A gas stream containing fluorine as a halogen and containing the fluorine in the form of a compound of an element selected from carbon, nitrogen and sulfur in the presence of steam in the presence of a catalyst comprising Al and about 200 to 800 A method for decomposing a fluorine-containing compound, comprising contacting at a temperature of ° C to hydrolyze a fluorine compound in the gas stream to convert it to hydrogen fluoride. 2. The method according to claim 1, wherein the gas stream containing the fluorine compound contains Al, Zn, Ni, Ti, Fe, S
A method for decomposing a fluorine-containing compound, which is brought into contact with a catalyst containing at least one selected from n, Co, Zr, Ce, Si and Pt. 3. The method according to claim 2, wherein the catalyst further contains S. 4. The method according to claim 2, wherein the components constituting said catalyst are contained in the form of an oxide of each component alone or a composite oxide of Al and other components. A method for decomposing a fluorine-containing compound. 5. The method according to claim 1, wherein the gas stream containing the fluorine compound is CF ₄ , CHF ₃ , C ₂ F ₆ , C
₃ F _8, wherein at least one of C ₄ F _8, C ₅ consisting of F ₈ fluorine compounds, fluorine-containing compounds, characterized by decomposing the fluorine compound and at least one and HF CO and CO ₂ Disassembly processing method. 6. The gas stream according to claim 1, wherein said gas stream containing a fluorine compound contains a fluorine compound comprising SF ₆ ,
_{6. A} method for decomposing fluorine-containing compounds, comprising decomposing ₆ into at least one of SO ₂ and SO ₃ and HF. 7. A gas flow according to claim 1, wherein said gas stream containing a fluorine compound contains a fluorine compound comprising NF ₃ , wherein said NF ₃ is formed of at least one of NO, NO ₂ and N ₂ O and HF.
And a method for decomposing fluorine-containing compounds. 8. A gas stream containing fluorine as a halogen and containing the fluorine in the form of a compound with an element selected from carbon, nitrogen and sulfur, in the presence of water vapor, a catalyst comprising Al and a gas stream comprising about 200 to 800 ° C. to hydrolyze the fluorine compounds in the gas stream to convert it to hydrogen fluoride, and then contact the gas stream containing the hydrogen fluoride with water to remove hydrogen fluoride. A method for decomposing a fluorine-containing compound, wherein water containing hydrogen fluoride is neutralized with an alkali. 9. A catalyst for use in hydrolyzing a halogen compound containing only fluorine as a halogen, said catalyst comprising an Al oxide and being used for decomposing a fluorine-containing compound. 10. The method according to claim 9, wherein Al, Zn, N
i, Ti, Fe, Sn, Co, Zr, Ce, Si and P
at least one selected from t.
l: M (M is Zn, Ni, Ti, Fe, Sn, Co, Z
r, Ce, Si).
A catalyst for decomposing fluorine-containing compounds, which is 0 to 99 mol% and M is 50 to 1 mol%. 11. The catalyst according to claim 10, further comprising 0.1 to 20% by weight of S. 12. The decomposition of a fluorine-containing compound according to claim 10, wherein each of the components is present in the form of an oxide of each component alone or a composite oxide of Al and other components. Processing catalyst. 13. The catalyst according to claim 10, wherein
And Pt, wherein Pt is contained in an amount of 0.1 to 2% by weight. 14. A reactor filled with a catalyst comprising Al, and a water adder for adding steam to a gas stream containing a compound of fluorine and one of carbon, sulfur and nitrogen to be treated in the reactor. And heating means for heating at least one of the catalyst filled in the reactor and the fluorine compound-containing gas stream introduced into the reactor to a temperature at which the fluorine compound can be hydrolyzed. Decomposition equipment for fluorine-containing compounds. 15. The fluorine-containing compound according to claim 14, further comprising an exhaust gas washing tank for washing a gas stream discharged from the reactor with water at a stage subsequent to the reactor. Decomposition equipment.