JP4459648B2 - Method and apparatus for treating gas containing fluorine-containing compound - Google Patents

Description

The present invention relates to the treatment of gases containing fluorine-containing compounds. In particular, the present invention relates to a method for treating an exhaust gas containing fluorine-containing compounds, particularly PFC, discharged from a step of dry-cleaning the inner surface of a semiconductor manufacturing apparatus in the semiconductor industry and a step of etching various film formations such as oxide films. And an apparatus. In addition to fluorine-containing compounds, the present invention also provides oxidizing gases such as F ₂ , Cl ₂ and Br ₂ , acidic gases such as HF, HCl, HBr, SiF ₄ , SiCl ₄ , SiBr ₄ and COF ₂ , and CO 2. TECHNICAL FIELD The present invention relates to an exhaust gas treatment method and a treatment apparatus capable of efficiently removing exhaust gas containing gas. In another aspect of the present invention, the present invention relates to a method and apparatus for recovering fluorine from a gas containing a fluorine-containing compound.

In the semiconductor industry, many kinds of harmful gases are used during the semiconductor manufacturing process, and there is a concern about environmental pollution due to exhaust into the environment. In particular, in a cleaning process of an inner surface of a semiconductor manufacturing apparatus in the semiconductor industry, an etching process, a CVD process, or the like, a fluorinated hydrocarbon such as CHF ₃ , CF ₄ , C ₂ F ₆ , C ₃ F ₈ , C ₄ F _6. , C ₄ F ₈ , C ₅ F ₈ , SF ₆ , and fluorine-containing compounds such as perfluoro compounds (PFC) such as NF ₃ are used. The fluorine-containing compounds contained in the exhaust gas from these processes are: As a global warming gas, it is urgently required to establish a removal system.

  As a method for treating exhaust gas containing a fluorine-containing compound, for example, a method of decomposing fluorocarbon in exhaust gas using a treatment agent containing aluminum oxide and an oxide of an alkaline earth metal (Patent Document 1); aluminum oxide and alkali Method of decomposing sulfur fluoride in exhaust gas using a treatment agent containing an oxide of earth metal (Patent Document 2); Decomposing fluorocarbon in exhaust gas using a treatment agent containing aluminum oxide and a lithium compound Method (Patent Document 3): A method of decomposing fluorine compounds in exhaust gas using a treating agent containing an oxide of metal such as alumina, an alkaline earth metal compound, and optionally copper, tin, vanadium (Patent Document 3) 4); Calcium oxide containing alkali metal chloride, alkaline earth metal chloride or alkali metal fluoride Or a method of decomposing halogenated gas in the exhaust gas by using the formed treatment agent by magnesium oxide (Patent Document 5); and the like have been proposed.

  However, the conventional processing method as described above has a problem that the processing temperature is as high as 800 to 1000 ° C., so that the processing apparatus is rapidly deteriorated by heat and the energy consumption of the apparatus is large. Moreover, the conventional processing agent included the problem that service life is short and replacement frequency is high. For example, in the methods disclosed in Patent Documents 1 to 3, PFC is decomposed by reacting PFC with aluminum oxide (alumina) to produce aluminum fluoride. However, since the reaction activity of aluminum oxide is low, high-temperature reaction conditions are necessary to allow this reaction to proceed efficiently. Furthermore, since the generated aluminum fluoride forms a layer on the surface of the aluminum oxide, the aluminum oxide is poisoned and loses the catalytic activity in a short time, so that the frequency of replacement of the treatment agent becomes high. is there.

  Furthermore, in recent years, resource depletion of fluorite, which is a raw material for fluorine, has become a problem, and the recovery and reuse of fluorine has become an important issue. When PFC is decomposed to produce aluminum fluoride, Since aluminum fluoride is a compound that does not dissolve in water, acid, or alkali, it is difficult in terms of cost and technology to recover fluorine from aluminum fluoride.

JP 2002-224565 A JP 2002-370013 A JP 2003-71244 A JP 2001-190959 A Japanese Unexamined Patent Publication No. 2000-157837 Japanese Patent No. 2569421 Japanese Patent No. 3217034 JP-A-7-204465

  The object of the present invention is to solve the problems of the prior art, to efficiently decompose PFC, and further to recover fluorine from the decomposed product and to reuse it, which can be reused. A processing method and a processing apparatus are provided.

  As a result of intensive research to develop a novel exhaust gas treatment method that solves the above-mentioned problems, the present inventors first added water to a gas containing PFC as a first stage process, and combined with an alumina-zirconium composite oxidation. PFC is decomposed as HF by bringing it into contact with a catalyst in which a tungsten oxide is supported on the support of the product, and then, as a second step, the produced HF is reacted with calcium hydroxide to generate fluorine. It has been found that by using calcium fluoride, the PFC in the gas can be decomposed and fluorine can be recovered in a reusable form, and the present invention has been completed. According to the method of the present invention, calcium fluoride is generated in the second step, and fluorine gas can be generated very easily by treating it with an inorganic acid such as hydrochloric acid or sulfuric acid. Therefore, according to this invention, while processing the gas containing PFC and making it harmless, it can collect | recover in a reusable form fluorine. That is, one embodiment of the present invention is a method for treating a gas to be treated containing a fluorine-containing compound, in which the gas to be treated is treated in a first step, and an oxide of tungsten is added to an alumina-zirconium composite oxide support. The present invention relates to a process characterized by reacting with water in the presence of a supported catalyst and then reacting with calcium hydroxide in the second stage.

  As a catalyst for decomposing fluorine compound gas, a catalyst in which an oxide of tungsten is supported on a support of an alumina-zirconium composite oxide has already been proposed (Patent Document 6). However, in this document, only the decomposition treatment of chlorofluorocarbon gas is intended, and application of this catalyst to the decomposition of PFC gas is not studied at all.

  In addition, a method of decomposing PFC as HF by reacting PFC gas with water in the presence of a catalyst has already been proposed (Patent Document 7). However, in this method, HF produced by the decomposition of PFC is dissolved in water by spraying the product gas with a water spray, and the resulting waste liquid is treated by neutralization, etc. There is no point of reuse.

  Furthermore, it has already been proposed to decompose exhaust gas containing hydrogen fluoride with calcium hydroxide (Patent Document 8). However, this is mainly intended for the treatment of exhaust gas containing acidic gas components such as hydrogen fluoride, and the treatment of PFC gas is not assumed. Further, it has not been studied at all to recover hydrogen fluoride decomposed by reacting with calcium hydroxide.

  In contrast to these conventional techniques, the present invention treats a gas containing a fluorine-containing compound such as PFC, particularly an exhaust gas from various processes of semiconductor manufacturing, decomposes the fluorine-containing compound, and easily recycles the fluorine. The present invention provides a method that can be recovered in a usable form, and this technical idea is not taught in the above-mentioned prior documents.

Fluorine-containing compounds that can be treated by the method of the present invention include fluorinated hydrocarbons such as CHF ₃ , perfluoro compounds (PFC) such as CF ₄ , C ₂ F ₆ , C ₃ F ₈ , SF ₆ , and NF _3. Etc. Examples of such a gas containing a fluorine-containing compound include exhaust gas discharged in a process of dry-cleaning the inner surface of a semiconductor manufacturing apparatus in the semiconductor industry and a process of etching various film formations.

The PFC decomposition catalyst that can be used in the present invention includes a catalyst in which an oxide of tungsten is supported on an alumina-zirconium composite oxide support described in Patent Document 6, that is, Al ₂ O ₃ —. A ZrO ₂ —WO ₃ -based catalyst can be used. For example, such a catalyst is obtained by dissolving a zirconium salt and aluminum oxyhydroxide (AlOOH) in deionized water, adding ammonia thereto to precipitate the product, and then filtering to wash a wet filter cake. It can be prepared by extruding, baking, and further impregnating with ammonium tungstate and baking.

  Furthermore, according to the method of the present invention, it is possible to detoxify exhaust gas containing an oxidizing gas such as fluorine gas in addition to PFC. Therefore, another aspect of the present invention relates to a method for detoxifying a gas to be treated containing a fluorine-containing compound and / or an oxidizing gas, which has the steps described above.

The exhaust gas discharged from the semiconductor manufacturing process may contain not only PFC but also oxidizing gases such as F ₂ , Cl ₂ , and Br ₂ . Oxidizing gases such as F ₂ , Cl ₂ , and Br ₂ cannot be completely treated with water alone when trying to perform wet treatment, and it is necessary to use an alkali agent or a reducing agent. However, there are problems such as complexity and cost. According to the method of the present invention, these oxidizing gases can also be decomposed together with a fluorine-containing compound such as PFC.

According to the method of the present invention, the fluorine-containing compound or the like in the gas to be treated is first converted into HF by reacting with water in the presence of the catalyst according to the present invention in the first step, and then the generated HF. However, it reacts with calcium hydroxide in the second step to become calcium fluoride. The reaction for decomposing CF ₄ as the PFC in the exhaust gas and F ₂ as the oxidizing gas by the method of the present invention is shown below.

  As a result of the above reaction, the second stage processing column after processing the gas to be processed contains a mixture of calcium hydroxide and calcium fluoride. By taking this out and treating it with an inorganic acid such as hydrochloric acid or sulfuric acid, fluorine gas can be generated very easily.

Moreover, according to the method of the present invention, in addition to PFC and oxidizing gas, exhaust gas containing acid gas can be detoxified. The exhaust gas discharged from the semiconductor manufacturing process may contain not only PFC and oxidizing gas but also acidic gas such as HF, SiF ₄ , COF ₂ , HCl, HBr, SiCl ₄ , and SiBr ₄ . According to the method of the present invention, it is possible to detoxify a gas to be treated containing these acidic gases in addition to PFC and oxidizing gas.

The above acidic gas, particularly SiF _4, is hydrolyzed to produce SiO ₂ when brought into contact with water. This SiO ₂ may block the piping of the first column in the method of the present invention. Furthermore, SiF ₄ reacts with alumina (Al ₂ O ₃ ), which is a catalyst used in the first stage reaction, to produce AlF ₃ , and this AlF ₃ forms a layer on the surface of alumina and poisons the catalyst. There is a problem (see the formula below).

Therefore, in the present invention, when a considerable amount of acidic gas such as SiF ₄ is included in the gas to be processed, the acidic gas is passed through the acidic gas removal column in advance before applying the gas to be processed to the first step. Is preferably removed. Therefore, another aspect of the present invention is a method for detoxifying a gas to be treated containing a fluorine-containing compound, an oxidizing gas, and an acid gas, the gas being treated by passing the gas to be treated through an acid gas removal column. After the pretreatment for decomposing the acidic gas therein, the gas to be treated is reacted with water in the presence of a catalyst in which an oxide of tungsten is supported on an alumina-zirconium composite oxide support in the first step. Then, in the second step, the method is characterized by reacting with calcium hydroxide at 500 to 800 ° C.

As the acidic gas removal column that can be used for such purpose, a column having a well-known configuration used for the purpose of removing acidic gases such as SiF ₄ and HF in the art can be used. A column can be suitably used. Specific examples of the acidic gas removal column that can be used in the method of the present invention include a dry exhaust gas treatment device GTE manufactured by Ebara Corporation.

Furthermore, CO may be contained in the exhaust gas discharged from the semiconductor manufacturing process, and since CO is generated as a by-product during the PFC decomposition reaction in the first step of the method of the present invention, it is decomposed. Need to be removed. According to the method according to another aspect of the present invention, a gas containing CO in addition to the fluorine-containing compound, the oxidizing gas, and the acidic gas can be removed. In this case, CO can be decomposed by adding oxygen to the gas to be processed. The timing of adding oxygen to the gas to be treated may be before the first stage process in which the gas to be treated is reacted with water in the presence of a catalyst, or may be during the first stage process. That is, another aspect of the present invention is a method for detoxifying a gas to be treated containing a fluorine-containing compound, an oxidizing gas, and CO, wherein oxygen is added to the gas to be treated in the first step. The gas to be treated is reacted with water in the presence of a catalyst in which an oxide of tungsten is supported on an alumina-zirconium composite oxide support, and then reacted with calcium hydroxide in the second step. It relates to the method. According to this process, CO of the process gas is oxidized and decomposed by the oxygen becomes CO ₂ in the processing column of the first stage (the following formulas).

  In the method of the present invention, PFC in the gas to be treated is reacted with water in the first stage reaction to decompose as HF, and then this HF is reacted with calcium hydroxide to form calcium fluoride. Calcium fluoride is a main component of fluorite known as a raw material for producing fluorine, and fluorine gas can be generated by treatment with acid. According to the method of the present invention, fluorine gas can be generated very easily by treating a mixture of calcium hydroxide and calcium fluoride produced in the second stage treatment column with an inorganic acid such as hydrochloric acid or sulfuric acid. Can do. Therefore, according to the method of the present invention, it is possible to recover fluorine in a reusable form from a gas containing a fluorine-containing compound very efficiently.

  In the method of the present invention, a gas to be treated containing a fluorine-containing compound and the like is reacted with water in the presence of a predetermined catalyst in the first stage, and then reacted with calcium hydroxide in the second stage. The reaction temperature of the reaction is generally 550 to 900 ° C, preferably 600 to 850 ° C, more preferably 750 to 800 ° C.

The reaction temperature of the second stage reaction may generally be room temperature. However, when a considerable amount of CO ₂ is contained in the gas to be treated introduced into the second stage treatment column, CO ₂ reacts with calcium hydroxide to produce calcium carbonate, which is calcium hydroxide. There may be a problem that the surface is inactivated and inactivated (see the following formula).

In this case, when the temperature of the treatment column is increased, the generated calcium carbonate is decarboxylated to become CaO, which reacts with HF to generate CaF ₂ , so that the decomposition efficiency of HF does not decrease (see the following formula).

Therefore, when it is considered that a considerable amount of CO ₂ is contained in the gas to be treated introduced into the second stage process, the reaction in the second stage process is also preferably performed under heating. The temperature in this case is preferably 500 to 800 ° C, more preferably 550 to 750 ° C, and still more preferably about 600 ° C.

  FIG. 1 shows a conceptual diagram of a gas processing apparatus capable of carrying out a method according to one embodiment of the present invention. The apparatus includes a first stage treatment column 2, a second stage treatment column 3, a gas introduction pipe 1 for introducing a gas to be treated into the first stage treatment column 2, a pipe 9 for supplying water to the gas introduction pipe 1, a first The column connection pipe 4 for connecting the stage processing column 2 and the second stage processing column and supplying the exhaust gas from the first stage processing column 2 to the second stage processing column 3, from the second stage processing column 3 An exhaust pipe 5 for discharging the product gas after the reaction is provided. The first stage treatment column 2 is packed with a catalyst 6 in which an oxide of tungsten is supported on an alumina-zirconium composite oxide support. The second stage treatment column 3 is filled with calcium hydroxide 7. Heating devices 8a and 8b are arranged on the outer circumferences of the first stage processing column 2 and the second stage processing column 3, respectively, and the inside of each processing column is heated and maintained at a predetermined temperature.

  A gas to be treated containing a fluorine-containing compound and the like passes through the gas introduction pipe 1 and water is added through the water supply pipe 9 and then introduced into the first stage treatment column 2 and is heated at a predetermined heating temperature to alumina-zirconium. In the presence of the catalyst 6 in which the oxide of tungsten is supported on the composite oxide support, it is reacted with water. Thereby, fluorine-containing compounds such as PFC and oxidizing gas in the gas to be treated are decomposed to generate HF. Although FIG. 1 shows a form in which the water supply pipe 9 is connected to the gas introduction pipe 1, the water supply pipe 9 is connected to the inside of the first stage treatment column 2 to perform the first stage treatment. You may make it supply in the column 2 directly.

The product gas from the first stage treatment column 2 is sent to the second stage treatment column 3 through the column connection pipe 4, where HF is reacted with calcium hydroxide to form CaF ₃ to form calcium hydroxide. It remains adsorbed on. The CO ₂ produced in the first stage treatment column 2 and the produced gas containing water vapor produced in the second stage treatment column 3 are discharged through the exhaust pipe 5.

By the intended reaction, the filler (calcium hydroxide) in the second stage treatment column 3 remains in the column in the form of a mixture adsorbing the produced calcium fluoride. Fluorine gas can be generated by taking out the treating agent after use, that is, a mixture of calcium fluoride and calcium hydroxide, and treating with a mineral acid such as hydrochloric acid or sulfuric acid. Therefore, according to the apparatus of the present invention, it is possible to very easily recover fluorine in a reusable form from a gas containing a fluorine-containing compound. In the case where CO is contained in the gas to be processed, or when it is considered that CO is generated by the processing reaction, oxygen is added to the gas to be processed from the oxygen supply pipe 10 and the inside of the first stage processing column 2 is added. Can simultaneously oxidize CO to CO ₂ . Similarly to the water supply pipe 9, the oxygen supply pipe 10 may be directly connected to the first processing column 2. Further, when an acid gas such as SiF ₄ is contained in the gas to be processed, an acid gas removing column (not shown) having a configuration known in the art is supplied before supplying the gas to be processed to the first stage processing column 2. It is preferable to decompose the acidic gas in the gas to be treated in advance.

Further, the inside of the processing column can be divided so that the first stage processing and the second stage processing can be performed within a single processing column. The concept of the gas processing apparatus according to another embodiment of the present invention having such a form is shown in FIG. In FIG. 2, the same components as those in FIG. 1 are denoted by the same reference numerals, and description thereof is omitted. The gas processing apparatus shown in FIG. 2 is a catalyst in which a single column 2 is divided into two parts, and an oxide of tungsten is supported on an alumina-zirconium composite oxide support in the first stage reaction section on the upstream side. 6 and the second-stage reaction part on the downstream side is filled with calcium hydroxide 7. As in the apparatus shown in FIG. 1, the gas to be treated 1 first reacts with water in the first stage reaction section in the presence of the catalyst 7 according to the present invention, and PFC or the like is converted into HF, which is then converted into the second stage. In the two-stage reaction section, it reacts with calcium hydroxide to become CaF ₂ . The inside of the processing column 2 is heated to a predetermined temperature by the heating device 8a. After the gas treatment, the calcium hydroxide adsorbed calcium fluoride is taken out from the second stage reaction part of the treatment column and treated with an inorganic acid such as hydrochloric acid or sulfuric acid to generate fluorine gas. it can.

The present invention also relates to an apparatus for treating a gas containing a fluorine-containing compound as described above.
Further, as described above, according to the method of the present invention, a gas containing a fluorine-containing compound or the like can be treated to recover fluorine in a recoverable form. Therefore, another aspect of the present invention also relates to a method and apparatus for recovering fluorine from a gas containing a fluorine-containing compound having the above-described configuration.

Various aspects of the present invention are as follows.
1. A method for treating a gas to be treated containing a fluorine-containing compound, wherein the gas to be treated is treated in the first step with water in the presence of a catalyst in which an oxide of tungsten is supported on an alumina-zirconium composite oxide support. And then reacting with calcium hydroxide at 500 to 800 ° C. in the second step.

2. A method for detoxifying a gas to be treated containing a fluorine-containing compound and an oxidizing gas, wherein the gas to be treated is supported on an alumina-zirconium composite oxide carrier in a first step. Reacting with water in the presence of a catalyst and then reacting with calcium hydroxide at 500-800 ° C. in the second stage.

3. A method for detoxifying a gas to be treated containing a fluorine-containing compound, an oxidizing gas, and an acid gas, wherein the gas to be treated is passed through an acid gas removal column to perform a pretreatment for decomposing the acid gas in the gas to be treated after the gas to be treated in the first stage process, alumina - oxide support in the tungsten-zirconium composite oxide is reacted with water in the presence of a catalyst which was supported, then in the second stage process, 500 Reacting with calcium hydroxide at ˜800 ° C.

4). A method for treating a gas to be treated containing a fluorine-containing compound, an oxidizing gas and CO, wherein oxygen is added to the gas to be treated, and the gas to be treated is treated with an alumina-zirconium composite oxide in the first step. And reacting with water in the presence of a catalyst having a tungsten oxide supported on the carrier, and then reacting with calcium hydroxide at 500 to 800 ° C. in the second step.

5). A method for detoxifying a gas to be treated containing a fluorine-containing compound, an oxidizing gas , an acid gas, and CO before the gas to be treated is passed through an acid gas removal column to decompose the acid gas in the gas to be treated After the treatment, oxygen is added to the gas to be treated, and in the first step, the gas to be treated is water in the presence of a catalyst in which an oxide of tungsten is supported on an alumina-zirconium composite oxide support. And then reacting with calcium hydroxide at 500 to 800 ° C. in the second step.

6. The method according to any one of items 1 to 5, wherein the temperature in the first step is 550 to 900 ° C.

9. An apparatus for processing a gas to be processed containing a nitrogen-containing compound,
A hollow interior in which the gas to be treated can be passed and a catalyst in which an oxide of tungsten is supported on an alumina-zirconium composite oxide support, a heating means capable of heating the temperature of the hollow interior to a predetermined temperature; A processing gas inlet for introducing the processing gas into the hollow interior, means for adding water to the processing gas before introducing the processing gas into the processing column, or adding water to the processing column A first stage treatment column comprising a water introduction tube;
Column connection piping for introducing the exhaust gas from the first stage processing column into the second stage processing column;
A hollow interior in which exhaust gas from the first column can be vented and filled with calcium hydroxide , heating means capable of heating the temperature of the hollow interior to a predetermined temperature, and an exhaust pipe for exhausting the generated gas from the hollow interior A second stage processing column.

10. An apparatus for detoxifying a gas to be treated containing a fluorine-containing compound and an oxidizing gas,
A hollow interior in which the gas to be treated can be passed and a catalyst in which an oxide of tungsten is supported on a support of an alumina-zirconium composite oxide is filled; a heating means capable of heating the temperature of the hollow interior to a predetermined temperature; A processing gas inlet for introducing the processing gas into the hollow interior, means for adding water to the processing gas before introducing the processing gas into the processing column, or adding water to the processing column A first stage treatment column comprising a water introduction tube;
Column connection piping for introducing exhaust gas from the first stage processing column into the second stage processing column;
A hollow interior in which exhaust gas from the first column can be vented and filled with calcium hydroxide , heating means capable of heating the temperature of the hollow interior to a predetermined temperature, and an exhaust pipe for exhausting the generated gas from the hollow interior A second stage processing column.

11. An apparatus for detoxifying a gas to be treated containing a fluorine-containing compound, an oxidizing gas, and an acidic gas,
An acidic gas removal column that decomposes and removes acidic gas in the gas by passing the gas to be treated;
A hollow interior in which a gas to be treated that has passed through an acid gas removal column can be vented and a catalyst in which tungsten oxide is supported on an alumina-zirconium composite oxide support is filled, and the temperature in the hollow interior is set to a predetermined temperature. A heating means capable of heating, a treatment gas introduction port for introducing the treatment gas into the hollow interior, a means for adding water to the treatment gas before introducing the treatment gas into the treatment column, or the treatment A first stage treatment column comprising a water introduction tube for adding water to the column;
Column connection piping for introducing the exhaust gas from the first stage processing column into the second stage processing column;
A hollow interior in which exhaust gas from the first column can be vented and filled with calcium hydroxide , heating means capable of heating the temperature of the hollow interior to a predetermined temperature, and an exhaust pipe for exhausting the generated gas from the hollow interior A second stage processing column.

12 An apparatus for detoxifying a gas to be treated containing a fluorine-containing compound, an oxidizing gas, and CO,
A hollow interior in which the gas to be treated can be passed and a catalyst in which an oxide of tungsten is supported on a support of an alumina-zirconium composite oxide is filled; a heating means capable of heating the temperature of the hollow interior to a predetermined temperature; Process gas inlet for introducing the process gas into the hollow interior, means for adding water to the process gas before introducing the process gas into the process column, or adding water to the process column A first stage treatment column comprising a water introduction tube;
Column connection piping for introducing the exhaust gas from the first stage processing column into the second stage processing column;
A hollow interior in which exhaust gas from the first column can be vented and filled with calcium hydroxide, a heating means capable of heating the temperature of the hollow interior to a predetermined temperature, and an exhaust pipe for exhausting the generated gas from the hollow interior A second stage processing column comprising:
Means for adding oxygen to the gas to be processed before introducing the gas to be processed into the first stage processing column or an oxygen introduction pipe for introducing oxygen into the first stage processing column;
The apparatus characterized by comprising.

13. An apparatus for detoxifying a gas to be treated containing a fluorine-containing compound, an oxidizing gas , an acidic gas, and CO,
An acidic gas removal column that decomposes and removes acidic gas in the gas by passing the gas to be treated;
A hollow interior in which a gas to be treated that has passed through an acid gas removal column can be vented and a catalyst in which tungsten oxide is supported on an alumina-zirconium composite oxide support is filled, and the temperature in the hollow interior is set to a predetermined temperature. A heating means capable of heating, a treatment gas introduction port for introducing the treatment gas into the hollow interior, a means for adding water to the treatment gas before introducing the treatment gas into the treatment column, or the treatment A first stage treatment column comprising a water introduction tube for adding water to the column;
Column connection piping for introducing the exhaust gas from the first stage processing column into the second stage processing column;
A hollow interior in which exhaust gas from the first column can be vented and filled with calcium hydroxide, a heating means capable of heating the temperature of the hollow interior to a predetermined temperature, and an exhaust pipe for exhausting the generated gas from the hollow interior A second stage processing column comprising:
Means for adding oxygen to the gas to be processed before introducing the gas to be processed into the first stage processing column or an oxygen introduction pipe for introducing oxygen into the first stage processing column;
The apparatus characterized by comprising.

15. The apparatus according to any one of Items 9 to 13 , wherein the hollow interior of the first stage treatment column is heated to 550 to 900 ° C.
16. The apparatus according to any one of Items 9 to 13, wherein the hollow interior of the second stage treatment column is heated to 500 to 800 ° C.

17. An apparatus for treating a gas to be treated containing a fluorine-containing compound,
A first-stage reaction section having a hollow interior through which the gas to be treated can be passed, the hollow interior being filled with a catalyst in which an oxide of tungsten is supported on an alumina-zirconium composite oxide support; A treatment column that receives exhaust gas from the first-stage reaction section and is divided into a second-stage reaction section filled with calcium hydroxide, and the temperature inside the hollow of the treatment column is a predetermined temperature. Heating means that can be heated to the first stage, a target gas inlet for introducing the target gas into the first stage reaction section, and the target process before introducing the target gas into the first stage reaction section of the processing column. Characterized in that it comprises means for adding water to the gas or a water introduction pipe for adding water to the first stage reaction section of the treatment column, and an exhaust pipe for discharging the product gas from the second stage reaction section of the treatment column. Device to do.

18. An apparatus for detoxifying a gas to be treated containing a fluorine-containing compound and an oxidizing gas,
A first-stage reaction section having a hollow interior through which the gas to be treated can be passed, the hollow interior being filled with a catalyst in which an oxide of tungsten is supported on an alumina-zirconium composite oxide support; A treatment column that receives exhaust gas from the first-stage reaction section and is divided into a second-stage reaction section filled with calcium hydroxide, and the temperature inside the hollow of the treatment column is a predetermined temperature. Heating means that can be heated to the first stage, a target gas inlet for introducing the target gas into the first stage reaction section, and the target process before introducing the target gas into the first stage reaction section of the processing column. Characterized in that it comprises means for adding water to the gas or a water introduction pipe for adding water to the first stage reaction section of the treatment column, and an exhaust pipe for discharging the product gas from the second stage reaction section of the treatment column. Device to do.

19. An apparatus for detoxifying a gas to be treated containing a fluorine-containing compound, an oxidizing gas, and an acidic gas,
An acidic gas removal column that decomposes and removes acidic gas in the gas by passing the gas to be treated;
A hollow interior through which the gas to be treated that has passed through the acid gas removal column can be passed, and the hollow interior is filled with a catalyst in which an oxide of tungsten is supported on an alumina-zirconium composite oxide support; A treatment column which is divided into a stage reaction section and a second stage reaction section which is adapted to receive exhaust gas from the first stage reaction section and is filled with calcium hydroxide; A heating means capable of heating the internal temperature to a predetermined temperature, a gas inlet for introducing the gas to be processed that has passed through the acidic gas removal column, and before introducing the gas to be processed into the first stage reaction section of the processing column And a means for adding water to the gas to be treated or a water introduction pipe for adding water to the first stage reaction section of the treatment column, and an exhaust pipe for discharging the product gas from the second stage reaction section of the treatment column. With features That equipment.

20. An apparatus for detoxifying a gas to be treated containing a fluorine-containing compound, an oxidizing gas, and CO,
A first-stage reaction section having a hollow interior through which the gas to be treated can be passed, the hollow interior being filled with a catalyst in which an oxide of tungsten is supported on an alumina-zirconium composite oxide support; A treatment column that receives exhaust gas from the first-stage reaction section and is divided into a second-stage reaction section filled with calcium hydroxide, and the temperature inside the hollow of the treatment column is a predetermined temperature. Heating means that can be heated to the first stage, a target gas inlet for introducing the target gas into the first stage reaction section, and the target process before introducing the target gas into the first stage reaction section of the processing column. Means for adding water to the gas or a water introduction pipe for adding water to the first stage reaction section of the treatment column, an exhaust pipe for discharging the generated gas from the second stage reaction section of the treatment column, and the gas to be treated to the first stage Before introduction into the treatment column. Oxygen introduction pipe for introducing oxygen to the means or the first stage treatment column adding oxygen sense gas, apparatus characterized by comprising a.

21. An apparatus for detoxifying a gas to be treated containing a fluorine-containing compound, an oxidizing gas , an acidic gas, and CO,
An acidic gas removal column that decomposes and removes acidic gas in the gas by passing the gas to be treated;
A hollow interior through which the gas to be treated that has passed through the acid gas removal column can be passed, and the hollow interior is filled with a catalyst in which an oxide of tungsten is supported on an alumina-zirconium composite oxide support; A treatment column which is divided into a stage reaction section and a second stage reaction section which is adapted to receive exhaust gas from the first stage reaction section and is filled with calcium hydroxide; A heating means capable of heating the internal temperature to a predetermined temperature, a gas inlet for introducing the gas to be processed that has passed through the acidic gas removal column, and before introducing the gas to be processed into the first stage reaction section of the processing column Means for adding water to the gas to be treated or a water introduction pipe for adding water to the first stage reaction section of the treatment column, an exhaust pipe for discharging the generated gas from the second stage reaction section of the treatment column, and the gas to be treated First stage processing Apparatus characterized by comprising an oxygen inlet tube for introducing oxygen to the means or the first stage treatment column adding oxygen to the gas to be treated before being introduced into the ram.

22. Item 22. The apparatus according to any one of Items 17 to 21, wherein the hollow interior of the treatment column is heated to 550 to 900 ° C.
23. A method of recovering fluorine by treating a gas to be treated containing a fluorine-containing compound, wherein the gas to be treated is supported in a first step, and a catalyst having tungsten oxide supported on an alumina-zirconium composite oxide support. In the presence of water, and then in the second step, it is reacted with calcium hydroxide at 500-800 ° C.

24. The method according to item 23, wherein the temperature in the first step is 550 to 900 ° C.

27. An apparatus for recovering fluorine by treating a gas to be treated containing a fluorine-containing compound,
A hollow interior in which the gas to be treated can be passed and a catalyst in which an oxide of tungsten is supported on a support of an alumina-zirconium composite oxide is filled; a heating means capable of heating the temperature of the hollow interior to a predetermined temperature; Process gas inlet for introducing the process gas into the hollow interior, means for adding water to the process gas before introducing the process gas into the process column, or adding water to the process column A first stage treatment column comprising a water introduction tube;
Column connection piping for introducing the exhaust gas from the first stage processing column into the second stage processing column;
A hollow interior in which exhaust gas from the first stage column can be vented and filled with calcium hydroxide , heating means capable of heating the temperature of the hollow interior to a predetermined temperature, an exhaust pipe for exhausting the generated gas from the hollow interior, A second stage processing column.

29. Item 28. The apparatus according to Item 27, wherein the hollow interior of the first stage treatment column is heated to 550 to 900 ° C.
30. 30. The apparatus according to item 28 or 29, wherein the hollow interior of the second stage treatment column is heated to 500 to 800 ° C.

31. An apparatus for recovering fluorine by treating a gas to be treated containing a fluorine-containing compound,
A first-stage reaction section having a hollow interior through which the gas to be treated can be passed, the hollow interior being filled with a catalyst in which an oxide of tungsten is supported on an alumina-zirconium composite oxide support; A treatment column that receives exhaust gas from the first-stage reaction section and is divided into a second-stage reaction section filled with calcium hydroxide, and the temperature inside the hollow of the treatment column is a predetermined temperature. Heating means that can be heated to the first stage, a target gas inlet for introducing the target gas into the first stage reaction section, and the target process before introducing the target gas into the first stage reaction section of the processing column. Characterized in that it comprises means for adding water to the gas or a water introduction pipe for adding water to the first stage reaction section of the treatment column, and an exhaust pipe for discharging the product gas from the second stage reaction section of the treatment column. Device to do.

  32. Item 32. The apparatus according to Item 31, wherein the hollow interior of the treatment column is heated to 550 to 900 ° C.

  The following examples further illustrate the present invention. The following description exemplifies several embodiments that embody the technical idea of the present invention, and the present invention is not limited by these descriptions.

Reference example 1
By the method of the present invention, a treatment test of a mixed gas of PFC (C ₄ F ₈ , C ₂ F ₆ , CF ₄ ), SiF ₄ as an acid gas, and CO was performed. Two stainless steel mini-columns with an inner diameter of 25 mm and a length of 500 mm are prepared, the Al ₂ O ₃ —ZrO ₂ —WO ₃ catalyst according to the present invention is used in the first column, and Ca (OH) ₂ is added to the second column. Filled and connected in series. As the catalyst based on Al ₂ O ₃ —ZrO ₂ —WO ₃ , a composition ratio (molar ratio) manufactured by Zude Chemie with an Al ₂ O ₃ : 0.75 / ZrO ₂ : 0.2 / WO ₃ : 0.05 A catalyst (ESW-1; granular product having a diameter of 2 mm and a length of 5 mm) was used to fill the layer height to 100 mm (filling amount: 49 mL). In addition, Ca (OH) ₂ was a commercially available product (manufactured by Yabashi Kogyo; 0.5 to 1.68 mm granular), and was filled so as to have a layer height of 100 mm (filling amount 49 mL). In order to measure the internal temperature of the catalyst layer in the first column, a thermocouple was arranged, and the first column was mounted in a ceramic electric tubular furnace. The first catalyst layer was heated to 750 ° C., and the second catalyst layer was kept at room temperature.

Necessary for decomposing C ₄ F ₈ , C ₂ F ₆ , CF ₄ , SiF ₄ , CO diluted with N ₂ , O ₂ and H ₂ O as additive gases, and PFC and CO into CO ₂ and HF, respectively. An amount exceeding the molar amount was introduced into the first column, and then passed through the second column. The total gas flow rate is 410 sccm, and the inflow concentration of each gas is 1340 ppm for C ₄ F ₈ , 390 ppm for C ₂ F ₆ , 500 ppm for CF ₄ , 440 ppm for SiF ₄ , 3.0% for CO, 4 for O ₂ 0.1% and the amount of H ₂ O introduced was 0.005 mL / min.

The outlet gas of each column is collected, and PFC, CO and CO ₂ are analyzed by a gas chromatograph mass spectrometer (Anelva, AGS-7000U), and SiF ₄ and HF are analyzed by an FT-IR analyzer (Matson, Infinity 6000). did. The removal rate of each PFC was calculated from the following equation.

Formula 1

  Table 1 shows the analysis results of the outlet gas after 3 hours. It can be seen that only HF leaked mainly from the outlet of the first tower, and HF was processed below the detection limit at the outlet of the second tower.

After 8 hours of continuous gas flow, HF leaked from the outlet of the second column to 3.5 ppm, exceeding the allowable concentration (3 ppm as HF). The total F amount (6.17 sccm as F) of the PFC that had been passed to this point was 2.51 g on a weight basis. The total amount of Ca (OH) _{2 in} the second tower was dissolved in aqua regia and the amount of F recovered was determined by quantitative analysis of the solution with respect to F using an ion chromatograph. As a result, the amount of F recovered was 2.47 g. It was 98.4%.

Example 2
In the same manner as in Reference Example 2, two columns filled with a catalyst were connected in series, and a thermocouple was placed in each column and mounted in a ceramic electric tubular furnace. The first column was heated to 750 ° C. in the same manner as in Example 1, and the second column was heated to 600 ° C.
Gas was passed under the same conditions as in Reference Example 1, and the outlet gas was analyzed. Table 2 shows the outlet gas concentration and the removal rate of each column when gas was passed for 8 hours. HF leaked mainly from the outlet of the first tower, and HF was removed below the detection limit at the outlet of the second tower. The PFC removal rate was even better than in Reference Example 1.

After 32 hours from passing through the gas, HF leaked from the outlet of the second tower at an allowable concentration level of 3 ppm. The total F amount of the PFC that had been passed to this point was 10.0 g on a weight basis. The second layer of Ca (OH) ₂ was treated in the same manner as in Reference Example 1 to obtain the amount of F recovered. As a result, it was 9.92 g, and the F recovery rate was 99.2%.

Example 3
The same two types of catalysts as in Reference Example 1, Al ₂ O ₃ —ZrO ₂ —WO ₃ catalyst and Ca (OH) ₂ were used. These were packed in the same stainless steel mini-column as used in Reference Example 1 with a layer height of 50 mm. The filling amount was 25 mL each. A stainless steel wire mesh (20 mesh) having a thickness of 0.8 mm was disposed between the two layers to separate the two layers. A thermocouple is arranged to measure the temperature inside the column, and it is mounted in a ceramic electric tube furnace so that the Al ₂ O ₃ —ZrO ₂ —WO ₃ layer is on the lower side and the Ca (OH) ₂ layer is on the upper side. did.

Each layer was heated to 750 ° C., and gas was passed therethrough in an upward flow under the same conditions as in Reference Example 1. Table 3 shows the column outlet gas concentration and the removal rate when 16 hours have passed after passing the gas. HF was processed below the detection limit.

18 hours after continuing the gas flow, HF leaked from the column outlet to an acceptable concentration level of 3.2 ppm. The total F amount of the PFC that had passed through this time was 5.35 g on a weight basis. The upper layer of Ca (OH) ₂ in the column was treated in the same manner as in Reference Example 1 and the recovered amount of F was determined to be 5.3 g. The recovery rate of F was 99.3%.

  According to the present invention, a gas containing a fluorine-containing compound is treated to decompose a fluorine-containing compound such as PFC and the like, and fluorine can be recovered in a reusable form. It can be treated and contributes to the recycling of fluorine, and its industrial value is great.

It is a conceptual diagram of the gas treatment apparatus concerning one mode of the present invention. It is a conceptual diagram of the gas processing apparatus concerning the other aspect of this invention.

Claims (12)

  A method for treating a gas to be treated containing a fluorine-containing compound, wherein the gas to be treated is treated in the first step with water in the presence of a catalyst in which an oxide of tungsten is supported on an alumina-zirconium composite oxide support. And then reacting with calcium hydroxide at 500 to 800 ° C. in the second step.   A method for detoxifying a gas to be treated containing a fluorine-containing compound, an oxidizing gas, and an acid gas, wherein the gas to be treated is passed through an acid gas removal column to perform a pretreatment for decomposing the acid gas in the gas to be treated Then, in the first stage, the gas to be treated is reacted with water in the presence of a catalyst in which an oxide of tungsten is supported on an alumina-zirconium composite oxide support, and then in the second stage, Reacting with calcium hydroxide at ˜800 ° C.   A method for treating a gas to be treated containing a fluorine-containing compound, an oxidizing gas and CO, wherein oxygen is added to the gas to be treated, and the gas to be treated is treated with an alumina-zirconium composite oxide in the first step. And reacting with water in the presence of a catalyst in which a tungsten oxide is supported on the carrier, and then reacting with calcium hydroxide at 500 to 800 ° C. in the second step. An apparatus for treating a gas to be treated containing a fluorine-containing compound,
The first stage reaction section in which the gas to be treated can be passed and the catalyst in which the oxide of tungsten is supported on the support of the alumina-zirconium composite oxide is filled, and the temperature of the first stage reaction section is set to 550 to 900. Heating means capable of heating to ° C. , gas inlet for introducing the gas to be treated into the first stage reaction section , water added to the gas to be treated before introducing the gas to be treated into the treatment column A first stage processing column comprising means for performing or a water introduction pipe for adding water to the processing column;
Column connection piping for introducing the exhaust gas from the first stage processing column into the second stage processing column;
A second stage reaction section which can vent the exhaust gas from the first stage column and filled with calcium hydroxide, a heating means which can heat the temperature of the second stage reaction section to 500-800 ° C. , the second A second stage treatment column comprising an exhaust pipe for discharging the product gas from the stage reaction section ;
The apparatus characterized by comprising. An apparatus for detoxifying a gas to be treated containing a fluorine-containing compound, an oxidizing gas, and an acidic gas,
An acidic gas removal column that decomposes and removes acidic gas in the gas by passing the gas to be treated;
A first-stage reaction section that is capable of venting the gas to be treated that has passed through the acid gas removal column, and is filled with a catalyst in which a catalyst in which tungsten oxide is supported on an alumina-zirconium composite oxide support is loaded; A heating means capable of heating the temperature of the first stage reaction section to 550 to 900 ° C. , a process gas inlet for introducing the process gas into the first stage reaction section , and introducing the process gas into the processing column. A first stage treatment column comprising means for adding water to the gas to be treated before water or a water introduction pipe for adding water to the treatment column;
Column connection piping for introducing the exhaust gas from the first stage processing column into the second stage processing column;
A second stage reaction section which can vent the exhaust gas from the first stage column and filled with calcium hydroxide, a heating means which can heat the temperature of the second stage reaction section to 500-800 ° C. , the second A second stage treatment column comprising an exhaust pipe for discharging the product gas from the stage reaction section ;
The apparatus characterized by comprising. An apparatus for detoxifying a gas to be treated containing a fluorine-containing compound, an oxidizing gas, and CO,
It can vent the gas to be treated, alumina - first stage reaction unit catalyst supported catalyst obtained by supporting an oxide of tungsten is filled in a carrier of zirconium complex oxide, the first stage reaction unit A heating means capable of heating the temperature to 550 to 900 ° C. , a gas inlet for introducing the gas to be processed into the first stage reaction section, and the gas to be processed before introducing the gas to be processed into the processing column. A first stage treatment column comprising means for adding water to the gas or a water introduction tube for adding water to the treatment column;
Column connection piping for introducing the exhaust gas from the first stage processing column into the second stage processing column;
A second stage reaction section which can vent the exhaust gas from the first stage column and filled with calcium hydroxide, a heating means which can heat the temperature of the second stage reaction section to 500-800 ° C. , the second A second stage treatment column comprising an exhaust pipe for discharging the product gas from the stage reaction section ;
Means for adding oxygen to the gas to be processed before introducing the gas to be processed into the first stage processing column or an oxygen introduction pipe for introducing oxygen into the first stage processing column;
The apparatus characterized by comprising. An apparatus for treating a gas to be treated containing a fluorine-containing compound,
A first stage having a hollow interior through which the gas to be treated can be passed, the hollow interior being filled with a catalyst in which a catalyst in which tungsten oxide is supported on an alumina-zirconium composite oxide support is supported. A treatment column that is adapted to receive the exhaust gas from the first reaction section and the second reaction section that is filled with calcium hydroxide, the first of the treatment columns . A heating means capable of heating the temperature of the stage reaction section and the second stage reaction section to 550 to 900 ° C. , a process gas inlet for introducing the process gas into the first stage reaction section, and the process gas From the means for adding water to the gas to be treated before being introduced into the first stage reaction section of the treatment column or the water introduction tube for adding water to the first stage reaction section of the treatment column, from the second stage reaction section of the treatment column Exhaust pipe to discharge the generated gas, Apparatus characterized by. An apparatus for detoxifying a gas to be treated containing a fluorine-containing compound, an oxidizing gas, and an acidic gas,
An acidic gas removal column that decomposes and removes acidic gas in the gas by passing the gas to be treated;
It has a hollow interior through which the gas to be treated that has passed through the acid gas removal column can be vented, and the hollow interior is filled with a catalyst in which a tungsten oxide catalyst is supported on an alumina-zirconium composite oxide support. A treatment column that is divided into a first stage reaction section that is arranged and a second stage reaction section that is adapted to receive the exhaust gas from the first stage reaction section and is filled with calcium hydroxide; A heating means capable of heating the first stage reaction section and the second stage reaction section of the processing column to a temperature of 550 to 900 ° C. , a processing gas inlet for introducing the processing gas that has passed through the acidic gas removal column, Means for adding water to the gas to be treated before introducing the gas to be treated into the first stage reaction section of the treatment column, or a water introduction pipe for adding water to the first stage reaction section of the treatment column, the second of the treatment column Generation from the stage reactor An exhaust pipe for discharging the scan, apparatus characterized by comprising a. An apparatus for detoxifying a gas to be treated containing a fluorine-containing compound, an oxidizing gas, and CO,
A first-stage reaction section having a hollow interior through which the gas to be treated can be passed, the hollow interior being filled with a catalyst in which an oxide of tungsten is supported on an alumina-zirconium composite oxide support; The treatment column is adapted to receive the exhaust gas from the first-stage reaction section and is divided into a second-stage reaction section filled with calcium hydroxide, the first-stage reaction section and the first-stage reaction section of the treatment column . A heating means capable of heating the temperature of the second stage reaction section to 550 to 900 ° C. , a target gas inlet for introducing the target gas into the first stage reaction section, and the first target gas of the processing column. Means for adding water to the gas to be treated before introduction into the stage reaction section or a water introduction pipe for adding water to the first stage reaction section of the treatment column, and discharge of the product gas from the second stage reaction section of the treatment column Exhaust pipe, first stage treatment of gas to be treated Apparatus characterized by comprising an oxygen inlet tube for introducing oxygen to the means or the first stage treatment column adding oxygen to the gas to be treated before being introduced into the ram.   A method of recovering fluorine by treating a gas to be treated containing a fluorine-containing compound, wherein the gas to be treated is supported in a first step, and a catalyst having tungsten oxide supported on an alumina-zirconium composite oxide support. And then reacting with calcium hydroxide at 600 to 800 ° C. in the second step. An apparatus for recovering fluorine by treating a gas to be treated containing a fluorine-containing compound,
The first stage reaction section in which the gas to be treated can be passed and the catalyst in which the oxide of tungsten is supported on the support of the alumina-zirconium composite oxide is filled, and the temperature of the first stage reaction section is set to 550 to 900. Heating means capable of heating to ° C. , gas inlet for introducing the gas to be treated into the first stage reaction section , water added to the gas to be treated before introducing the gas to be treated into the treatment column A first stage processing column comprising means for performing or a water introduction pipe for adding water to the processing column;
Column connection piping for introducing the exhaust gas from the first stage processing column into the second stage processing column;
A second stage reaction section which can vent the exhaust gas from the first stage column and filled with calcium hydroxide, a heating means which can heat the temperature of the second stage reaction section to 500-800 ° C. , the second A second stage treatment column comprising an exhaust pipe for discharging the product gas from the stage reaction section ;
The apparatus characterized by comprising. An apparatus for recovering fluorine by treating a gas to be treated containing a fluorine-containing compound,
A first-stage reaction section having a hollow interior through which the gas to be treated can be passed, the hollow interior being filled with a catalyst in which an oxide of tungsten is supported on an alumina-zirconium composite oxide support; The treatment column is adapted to receive the exhaust gas from the first-stage reaction section and is divided into a second-stage reaction section filled with calcium hydroxide, the first-stage reaction section and the first-stage reaction section of the treatment column . A heating means capable of heating the temperature of the two-stage reaction section to 550 to 900 ° C. , a process gas inlet for introducing the process gas into the first stage reaction section, and the process gas as a first of the processing column. Means for adding water to the gas to be treated before introduction into the stage reaction section or a water introduction pipe for adding water to the first stage reaction section of the treatment column, and discharge of the product gas from the second stage reaction section of the treatment column An exhaust pipe Device that.

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