JP2001062241A - Filter for separating perfluorinated compound and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a filter for separating a gaseous perfluorinated compd. suitable for efficiently separating the gaseous perfluorinated compd. from the mixed gas containing gaseous perfluorinated compd. and concentrating it and to provide its production device. SOLUTION: A separation membrane 3 consisting of the porous oxide containing silicon and zirconium having many fine pores 5 is formed on at least one side surface of a porous supporting body 2 by coating, and the mixed gas containing the gaseous perfluorinated compd. and the specified gas lower in molecular diameter than the perfluorinated compd. is brought into contact with one side surface of the separation membrane 3, and the gaseous perfluorinated compd. is separated and concentrated by selectively and efficiently permeating the specified gas to the other surface of the separation membrane 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a perfluoro compound gas separation filter for separating a perfluoro compound gas from a mixed gas containing a plurality of gases, and a method of manufacturing the same. The present invention relates to a perfluoro compound gas separation filter capable of separating a perfluoro compound gas from exhaust gas in a process and having excellent corrosion resistance, water resistance and heat resistance, and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, a filter for filtering and separating a specific gas from a mixed gas containing various gases, a catalyst carrier,
Furthermore, a porous body is used as an electrolytic partition or the like,
Because of its safety and simplicity, its application range is expanding, and the technology for separating and concentrating specific gases using porous materials has attracted attention in the fields of various combustion engines, the food industry, medical equipment, and even waste disposal. ing.

[0003] On the other hand, perfluoro compounds are widely used, for example, as refrigerants for refrigerators and air conditioners and as solvents for the manufacture of semiconductors. They are known as substances that destroy the environment, and their emissions are regulated. Thus, methods for separating and recovering perfluoro compounds have been studied.

For example, Japanese Patent Application Laid-Open No. 9-103633,
JP-A-10-128034, JP-A-10-263
No. 376 discloses that a perfluoro compound gas can be separated and concentrated using a polymer gas separation filter.

[0005]

However, the above-mentioned filter made of a polymer is based on a so-called dissolution-diffusion phenomenon in which a gas is dissolved in a separation membrane and the gas is diffused in the membrane to transmit the gas. Therefore, there is a problem that the gas transmission speed is low.

Further, the heat resistance and corrosion resistance of the filter are poor, and the filter cannot be used for a mixed gas containing an acidic or alkaline gas or a high-temperature gas.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a perfluoro compound gas separation filter capable of separating and concentrating a perfluoro compound gas from a plurality of mixed gases containing a perfluoro compound gas. Perfluoro-compound gas separation with excellent corrosion resistance, heat resistance, and water resistance, which has excellent gas separation characteristics such as transmittance and transmission coefficient ratio, and can maintain high separation characteristics even in a high temperature environment from room temperature to 400 ° C. An object of the present invention is to provide a filter and a manufacturing method thereof.

[0008]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies on the above-mentioned problems, and as a result, have found that the surface of the porous support has an S surface.
Using a gas separation filter composed of a separation membrane formed by applying an amorphous oxide containing i and Zr, one surface of the gas separation filter has a molecular diameter larger than that of the perfluoro compound gas and the perfluoro compound. Contact with a mixed gas containing a specific gas having a small diameter, selectively permeate the specific gas to the other surface of the separation membrane, and separate the perfluoro compound gas, and provide corrosion resistance, heat resistance and water resistance. It has been found that a perfluoro compound gas separation filter having excellent and stable separation characteristics can be obtained.

Here, the average pore diameter of the amorphous oxide containing Si and Zr is desirably 2.5 to 10 °, and the atomic ratio of the Si and Zr (Z
(r / Si) desirably has a ratio of 0.01 to 0.5.

Further, as a characteristic of the filter, the transmittance of nitrogen gas from normal temperature to 350 ° C. is 10 ⁻⁸ mol / (m
² · Pa · sec) or more, a nitrogen (N ₂₎ and permeability coefficient ratio of the perfluoro compound gas _{(PF) (N 2 / PF} ) are those desirably 4 or more.

The method for producing a perfluoro compound gas separation filter of the present invention comprises the steps of mixing a silicon alkoxide and a zirconium alkoxide in an alcohol solvent to prepare a composite alkoxide, and hydrolyzing the composite alkoxide. A step of preparing a precursor sol; and a step of applying the precursor sol to at least one surface of a porous support, drying the sol, and then baking the precursor sol at a temperature of 350 to 700 ° C. Things.

Further, the silicon alkoxide is tetraalkoxysilane and the general formula is

[0013]

Embedded image

It is a mixture of another alkoxysilane having an organic functional group represented by the formula, and the content of the other alkoxysilane in the total amount of the silicon alkoxide is preferably 3 to 50 mol%.

[0015]

According to the perfluoro compound gas separation filter of the present invention, since the separation membrane is composed of a composite oxide composed of Si and Zr, the corrosion resistance to acids and alkalis can be improved.

Further, the separation membrane is made of a porous material, and its pore diameter is controlled to such a size that a perfluoro compound gas cannot be permeable and a specific gas having a molecular diameter smaller than the perfluoro compound gas can be permeable. Since only the specific gas smaller than the pore diameter is transmitted through the space in the pores by diffusion, the gas permeation resistance is small, the gas separation speed is high, and the gas separation performance is improved.

Further, in the structure in the separation membrane, Si
Since Zr is interposed between the siloxane bonds represented by —O, the stability of the siloxane bond can be increased, and the pore size changes without changing the bonding state even at high temperature and / or in the presence of moisture. Because there is nothing to do
The heat resistance can be increased, and the water resistance and also the corrosion resistance can be increased.

Further, according to the method for producing a perfluoro compound gas separation filter of the present invention, the other alkoxide of silicon comprises the tetraalkoxysilane and the other alkoxysilane having an organic functional group. The organic functional group of the alkoxysilane becomes a steric hindrance when forming the sol. That is, when a siloxane bond is formed by hydrolysis, a cyclic siloxane bond is formed so as to surround the organic functional group. For this reason, a siloxane-bonded cyclic body having a desired size, that is, a pore skeleton can be formed in the sol by the organic functional group.

Further, when this is heat-treated at a predetermined temperature, the organic functional groups are decomposed and removed by the heat treatment to form pores. Can inhibit excessive growth of, so that fine pores having a pore size of the order of Å can be left, for example, 3.64.
Nitrogen (N ₂ ) gas having a molecular diameter of Å is preferentially permeated, and can be separated from a perfluoro compound gas having a molecular diameter of more than 3.64Å.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION One example of a perfluoro compound (hereinafter abbreviated as PF) gas separation filter of the present invention is described below.
FIG. 1 shows a partially enlarged cross-sectional view thereof. The PF gas separation filter 1 of the present invention includes a porous support (hereinafter, simply referred to as a support) 2 and an amorphous oxide containing Si and Zr formed on at least one surface of the support 2. 3 (hereinafter, abbreviated as a separation membrane).

(Separation Membrane) FIG. 2 is a partially enlarged view of the separation membrane 3 of the PF gas separation filter of the present invention. As shown in FIG. 2, the separation membrane 3 is basically made of Si—O—
It is important to control the pore diameter to be composed of amorphous silica having a cyclic siloxane bond represented by Si,
The pore formed by the cyclic siloxane bond is P
The permeation of the specific gas other than the F gas allows the PF gas to be separated.

Further, it is important to have a structure in which a part of the Si is replaced by Zr in order to enhance heat resistance and water resistance, and the atomic ratio (Zr / Sr) of the Si and the Zr is important.
i) is from 0.01 to 0.5, especially from 0.1 to 0.5 in terms of improvement in heat resistance and water resistance and stability of the sol generated during production.
It is desirable to have a ratio of 3.

From the viewpoint of improving the gas separation characteristics, the average pore diameter of the separation membrane 3 is 2.5 to 10 °, especially 2.5 to 5 °.
望 ま し く is desirable, and the film thickness is 0.01 to 1 μm,
In particular, the thickness is desirably 0.01 to 0.5 μm.

For example, when SF ₆ and N ₂ are separated,
The average pore diameter of the separation membrane 3 is larger than the molecular diameter of N ₂ and smaller than that of SF _6.
In the case of separating ₄ from N ₂ , 0.36 to 0.4n
m is desirable.

In the present invention, the PF gas refers to a compound gas containing any one of carbon (C), sulfur (S) and nitrogen (N) and fluorine (F). , CF ₄ , C ₂ F ₆ , C ₃ F ₈ , C ₄ F _{10 and the} like, hydrofluorocarbons such as CHF ₃ , CH ₂ F ₂ and CH ₃ F, SF ₆ , NF _{3 and the} like.

The specific gas smaller than the PF gas is
Inorganic gases such as H ₂ , H ₂ O, N ₂ , O ₂ and CO ₂ , organic gases such as methane and ethane, and gases having a smaller molecular diameter than PF gases such as alcohols such as methanol and ethanol.

Further, the separation membrane 3 formed on the surface of the support 2 does not generate a reaction product at the interface with the support 2, and is coated in a layer on the surface of the support 2 to provide a smooth surface. It is desirable to form a surface.

(Porous Support) The support 2 has a strength of 0.1 to 2 in that it can transmit a specific gas, has a necessary strength as a structural body, and enhances the film-forming property of the separation membrane 3.
It is desirable to have a pore size of μm. Further, in order for the mixed gas to pass through the support 2 without applying a high pressure, the support 2 preferably has a porosity of 20% or more. When assembling 1, in order to prevent the support from being broken or particles constituting the support 2 from falling during operation,
The porosity of the support 2 is desirably about 40%.

The support 2 can be formed of ceramics mainly composed of α-alumina or stabilized zirconia, silica-based glass (phase-separated glass), or the like, but has high heat resistance, can be easily manufactured, and has low cost. From the viewpoint, it is desirable to use ceramics containing α-alumina as a main component.

In order to enhance the film forming property of the separation membrane 3, it is desirable that the support 2 has a smooth surface having a surface roughness (Ra) of 0.1 to 2.0 μm.

(Intermediate Layer) It is desirable that an air-permeable intermediate layer (hereinafter, abbreviated as “intermediate layer”) 4 is interposed between the support 2 and the separation membrane 3. Thereby, since the film forming property of the separation membrane 3 on the support 2 is improved, the thickness of the separation membrane 3 can be reduced, and the speed of gas separation is improved.

Here, the average pore diameter of the intermediate layer 4 depends on the permeation rate of the PF gas and the film-forming property of the separation membrane 3.
Is smaller than the average pore diameter of the separation membrane 3 and larger than the average pore diameter of the separation membrane 3.
m, especially 2 to 5 nm.

The intermediate layer 4 may be any material that does not generate a reaction product between the support 2 and the separation membrane 3 and covers the surface of the support 2 in a layered manner to form a smooth surface.

For example, when α-alumina ceramics is used as the support 2, γ
-Alumina is preferred.

(Filter) The shape of the support 2 is not particularly limited, and may be a flat plate or a tubular body. However, a tubular body may be used in consideration of gas separation efficiency and handling of the filter. desirable.

In the above case, the diameter of the tubular body is desirably about 2 mm for improving the gas separation efficiency.
In order to maintain strength that does not hinder handling, it is desirable that the wall thickness of the tubular body be 0.2 to 1 mm. In the case of a flat filter, in terms of strength, the thickness of the support is:
Desirably, it is 0.3 mm or more.

In the above configuration, the separation membrane 3 is used as the support 2
Is formed on the inner surface and / or the outer surface, and the thickness of the separation membrane 3 is 0.01 to 1 μm in view of improving the gas separation speed.
It is desirable that

The PF gas separation filter 1 according to the present invention comprises a support 2 and a separation membrane 3.
By flowing a mixed gas and a specific gas containing a PF gas on one surface of the filter and lowering the partial pressure of the specific gas in the mixed gas on the surface on the opposite side of the filter 1, the specific gas is separated from the support 2 and the separation membrane. 3, the PF gas can be selectively permeated and separated to the other surface, and the PF gas can be efficiently separated and concentrated from the mixed gas.

As a gas transmission path, the gas may pass through the support 2 and then through the separation membrane 3, or conversely, may pass through the separation membrane 3 and then pass through the support 2. Further, when the support 2 is formed of a tubular body, a mixed gas is allowed to flow in the tubular body, and a specific gas other than the PF gas is allowed to permeate outside the tubular body, and can be separated and recovered. The specific gas can be allowed to permeate inside the tubular body while flowing the mixed gas outside the tubular body.

As a method for lowering the partial pressure of the specific gas, a gas other than the specific gas can be supplied to the specific gas discharge surface side. By lowering the pressure on the side, the PF gas can be separated and concentrated more efficiently.

The method of providing the above-mentioned pressure difference is as follows.
A method of depressurizing the specific gas discharge surface side, a method of pressurizing the mixed gas supply surface side containing the specific gas, and a method of using the above two methods in combination are exemplified.

The PF gas separation filter 1 of the present invention having the above-described structure has a nitrogen gas transmittance of 1 × 10 ⁻⁸ mol / (m ² · Pa · sec) or more at a temperature from normal temperature to 350 ° C.
The transmission coefficient ratio (N ₂ / PF) between nitrogen gas and PF gas is 4
A PF gas separation filter having the above excellent characteristics is obtained.

The PF gas separation filter 1 of the present invention having the above structure can be used over a wide temperature range from room temperature to 400 ° C., particularly 350 ° C. in view of the heat resistance and durability of the separation membrane 3. is there.

(Module) FIG. 3 shows an example of a PF gas separation apparatus for separating PF gas using the PF gas separation filter of the present invention. According to FIG. 3, the PF gas separation device 11
Has an inner diameter of 1 to 5 mm, a thickness of 0.2 to 1 mm, and a length of 50 to
About 500 to about several hundred cylindrical PF gas separation filters 12 each having a diameter of 500 mm are fixed by a fixing member 13, and are further adhesively fixed in a housing 14.

The fixing member 13 and the housing 14 are
Resin such as vinyl chloride or polyurethane, metal such as stainless steel, dense ceramics such as alumina or zirconia, or a material such as glass which does not transmit gas. The housing 14 is formed by pressurizing or depressurizing the system. In the case of heating the apparatus, those having high mechanical strength such as metal and ceramics are preferable.

When the fixing member 13 is used at a high temperature, it is desirable that the fixing member 13 is bonded and fixed by a structure that relieves stress caused by a difference in thermal expansion coefficient between the filter and the housing.

Further, the housing 14 has a mixed gas inlet 15 for introducing a mixed gas into the system, and a permeated gas outlet 16 for separating and recovering gas permeating the separation membrane.
And a mixed gas outlet 17 for discharging the mixed gas passing through the surface of the gas separation filter 12 to the outside of the system,
Gas enters and exits only at the above three locations.

According to the PF gas separation device 11, a pressure difference can be provided in the system.
A vacuum pump or the like (not shown) may be connected to the PF gas separation filter 12 to reduce the pressure on the outer peripheral surface of the PF gas separation filter 12.

(Production Method) (Raw Material for Separation Membrane) Next, a method for producing the PF gas separation filter of the present invention will be described. First, an alkoxide of silicon and an alkoxide of zirconium are prepared. As the silicon alkoxide, tetraalkoxysilane and a general formula represented by the following formula 1

[0050]

Embedded image

It is desirable to use another alkoxysilane having an organic functional group represented by the following formula.

Specifically, tetraalkoxysilanes include tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, and the like, and tetramethoxysilane or tetraethoxysilane is used in view of the cost of raw materials and film-forming properties. Is desirable.

As the other alkoxysilane, an organic functional group causes a steric hindrance during the formation of the sol, and can form a pore skeleton of a desired size in the sol. It is necessary to control the pore diameter to 10 ° or less, and silicon alkoxides having organic functional groups of appropriate size are desirable.

Further, the pore skeleton is set to a desired range, and 2.5
In order to obtain a separation membrane having a pore diameter of 10 to 10 °, the content of the other alkoxysilane in the total amount of the alkoxide of silicon is desirably 3 to 50 mol%.

As the alkoxide of zirconium, tetraethoxyzirconium, tetrapropoxyzirconium, tetrabutoxyzirconium and the like can be used. From the viewpoints of solubility in alcohol and film-forming property of gel,
Tetraethoxyzirconium and tetrapropoxyzirconium are desirable, and the atomic ratio (Zr / Si) of the total Si to the Zr is 0.01 to 0 in view of improvement in heat resistance and water resistance and stability of a sol generated during the production. .5, preferably 0.1 to 0.3.

Next, each of the above alkoxides is dissolved in a solvent. As the solvent, alcohols such as methanol, ethanol, propanol, butanol, 2-methoxyethanol, and 2-ethoxyethanol are preferably used, and the solubility of the alkoxide and the affinity for the gel support and the drying property are preferable. From the viewpoint of film forming property, a lower alcohol such as methanol or ethanol is most suitable.

As for the tetraalkoxysilane, it is desirable to add 1 to 3 mol of water to 1 mol of the tetraalkoxysilane together with an acid or the like together with a solvent to partially hydrolyze the tetraalkoxysilane. The homogeneity of the composition in the solution can be enhanced by reacting the oxidized portion with the alkoxide of trialkoxysilane and zirconium.

Next, the above alkoxide solution was mixed,
After stirring under a nitrogen stream to produce a composite alkoxide,
This is hydrolyzed by a known hydrolysis method in which water, acid or the like having a predetermined concentration is added to produce a sol. The amount of water to be added for the hydrolysis is 1 to 1 mol of alkoxide of all silicon in the alkoxide solution.
-20 mol is desirable.

That is, when the amount of the water is less than 1 mol, hydrolysis is not sufficient, and siloxane bonds do not proceed, so that the film-forming property is poor, cracks occur in the film, and the film peels off. When the amount of the water is more than 20 mol, the hydrolysis proceeds too rapidly, and a precipitate or the like is generated, so that a stable sol cannot be obtained.

(Support) On the other hand, in order to produce a porous support, for example, a predetermined amount of a binder, a lubricant, a plasticizer, water and the like are added to an alumina raw material having an average particle size of 0.1 to 2.0 μm. After the addition and mixing, the mixture is molded by a known molding means such as press molding, extrusion molding, injection molding, and cold isostatic pressing. Thereafter, the molded body is placed in the atmosphere at 1000 to 1000
By firing at 1500 ° C., a porous support can be obtained.

The support has the above-mentioned material, porosity, average pore diameter and surface roughness (Ra).
It is desirable to have a flat surface of 0.1 to 2 μm,
Moreover, it is desirable that it is a tubular body with an inner diameter of 2 mm and a wall thickness of 0.3 to 1 mm.

(Intermediate layer) As a method of forming the intermediate layer, for example, a boehmite sol is prepared by hydrolyzing an aluminum alkoxide such as aluminum secondary butoxide, and the boehmite sol is formed on the surface of the porous support. The sol is deposited.

The method of applying the boehmite sol to the surface of the support is preferably a method of applying or pouring the boehmite sol, or a method of impregnating the porous support into the boehmite sol solution and pulling up. Used.

Thereafter, the adhered boehmite sol is dried and gelled, and this is dried at 400 to 900 ° C. in the air.
In particular, an intermediate layer can be formed on the surface of the support by heat treatment at 400 to 600 ° C. If the firing temperature is lower than 400 ° C., the bonding strength of the intermediate layer to the support is weak and the intermediate layer is peeled off.
If the temperature is higher than 0 ° C., sintering proceeds excessively, and the pore size of the intermediate layer becomes large, so that a desired pore size cannot be obtained.

(Separation Membrane) Next, a sol containing Si and Zr is formed on the surface of the porous support or the intermediate layer by the same method as that for forming the intermediate layer, and then dried to form a gel. Become

Then, the support on which the gel containing Si and Zr is adhered is heat-treated at 350 to 700 ° C., particularly 400 to 500 ° C. in the air, so that the Si in the gel is formed.
The siloxane bond of —O progresses to form a strong film, and the organic functional groups are decomposed and removed by heat treatment to form pores.

At this time, a part of the organic functional group may remain even after firing, whereby excessive progress of siloxane bond can be prevented and the pore diameter can be controlled in a desired range. .

The film is preferably an aggregate of colloid particles, and the gap between the colloid particles is 2.5
It is desirable that pores of 10 to 10 ° be formed.

The reason why the firing temperature is limited to the above range is that if the firing temperature is lower than 350 ° C., siloxane bonds cannot be strengthened, a stable film cannot be formed, and a desired diameter cannot be obtained. Cannot be obtained. If the firing temperature is higher than 700 ° C., the separation membrane is crystallized, and the pores in the membrane cannot have a desired diameter.

That is, in such a system, by baking at a predetermined temperature, a part of the organic functional group remains in the film even after the heat treatment, so that the excessive growth of the siloxane bond can be inhibited. Which allows fine pores having a pore size of Å order to be present in the film, so that a specific gas is preferentially produced from a mixed gas containing PF and a specific gas having a smaller molecular diameter than PF. By permeating, the PF gas can be separated and concentrated.

[0071]

EXAMPLES (Example 1) First, an ethanol solution containing 0.7 mol of water and HCl was added to tetraethoxysilane (abbreviated as TEOS) and mixed to prepare a partially hydrolyzed sol. An ethanol solution of trialkoxysilane (abbreviated as TAS) shown in Table 1 is added, and the mixture is stirred under a nitrogen stream, and then ethanol of tetrapropoxyzirconium (abbreviated as TPZ) which is an alkoxide of zirconium in the amount shown in Table 1. The solution was added to produce a composite alkoxide.

Next, 9.3 m of water was added to the composite alkoxide.
The mixture was hydrolyzed by adding a mixed solution of ol and ethanol, and further stirred for 3 hours to prepare a precursor sol.

On the other hand, the purity was 99.9% and the average particle size was 0.1 μm.
m of alumina, a predetermined amount of an organic binder, a lubricant,
After adding and mixing a plasticizer and water, forming into a tubular body by extrusion molding, firing in the air at 1200 ° C., the inner diameter of the tubular body is 2 mm, the wall thickness is 0.4 mm, and the length is 250 mm. An α-alumina porous support having a particle size of 0.2 μm and a porosity of 39% was produced. Further, the outer surface was polished so that the surface roughness (Ra) became 0.3 μm.

Further, 1 mol of aluminum secondary butoxide was added to 110 mol of water for hydrolysis, nitric acid was further added, and the mixture was refluxed for 16 hours to prepare a boehmite sol. Then, the tip of the support is plugged, impregnated in the boehmite sol solution, held for 60 seconds, discharged at a speed of 5 mm / sec, and dried at room temperature for 2 hours to gel the boehmite sol. After that, the step of calcining the support on which the gel is formed at 500 ° C.
The intermediate layer made of γ-alumina was formed on the surface of the α-alumina porous support by repeating the process repeatedly.

Then, the support on which the intermediate layer was formed was immersed in the obtained precursor sol solution for 30 seconds.
After pulling up at a speed of mm / sec and drying at room temperature for 1 hour,
Subsequently, the temperature was maintained at the firing temperature shown in Table 1 for 1 hour, and then cooled to room temperature. This series of operations of immersion, drying, and firing was repeated four times, and a separation membrane containing Si and Zr was deposited on the γ-alumina layer to produce a PF gas separation filter.

As a comparative example, a sample to which zirconium was not added (sample No. 18) was produced in the same manner as described above.

The appearance of the obtained sample was examined by SEM observation. Further, the average pore diameter of the separation membrane was determined by an argon adsorption method. Further, an intermediate layer and a separation membrane are formed on one surface of a 20 mm square plate-shaped support prepared by the same method as above, and the X-ray diffraction measurement of the separation membrane is performed. analyzed. The results are shown in Table 1.

[0078]

[Table 1]

Using the obtained filter, the above-mentioned PF gas separation apparatus 11 was manufactured. The filter was set in a furnace at the temperature shown in Table 2, and helium gas was supplied to the outside of the tube at 30 cc / min. While flowing, nitrogen was added to the inside of the tube.
A mixed gas of 5 atm and 0.5 atm of tetrafluoromethane (CF ₄ ) was flowed at a rate of 100 cc / min, and the total flow rate of the gas collected at the permeated gas outlet 17 was measured using a membrane flow meter. The concentration of nitrogen passing through the filter was measured using gas chromatography, the amount of nitrogen permeation was calculated, and the amount of nitrogen permeation / (membrane area × differential pressure ×
H) was calculated.

Further, the transmittance of the perfluoro compound gas was determined in the same manner as described above, and the transmission coefficient ratio α of the perfluoro compound gas (the transmittance of nitrogen / the transmittance of PF) was determined.

In the above measurement, pretreatment was carried out for 1 hour in a flow of He gas at each temperature before the measurement, and evaluation was performed with the filter at each temperature. The results are shown in Table 2.

Comparative Example Poly (4-methylpentene)
A filter having the same dimensions as in Example 1 comprising 1) was prepared, and the gas separation characteristics were evaluated in the same manner as in Example 1 (sample N).
o. 22).

[0083]

[Table 2]

As is clear from Tables 1 and 2, the sample No. consisting of a polymer filter was used. In No. 22, the permeability of nitrogen gas was low, and at a high temperature, the separation membrane deteriorated and could not permeate the gas. In addition, sample N containing no zirconium
o. In No. 18, the nitrogen gas transmittance and the transmission coefficient ratio α were low.

Further, a sample N consisting of a composite oxide crystal phase
o. In No. 21, the average pore diameter was not measurable, that is, it was densified, and the nitrogen gas transmittance was lower than the measurement limit.

On the other hand, the sample No. Samples Nos. 1 to 17, 19, and 20 all exhibited high nitrogen gas permeability and high gas separation performance with a transmission coefficient ratio α of 15 or more.

(Example 2) Sample No. 1 of Example 1 With respect to 2, gas separation at room temperature was performed in the same manner as in Example 1 except that tetrafluoromethane (CF ₄ ) in the gas separation evaluation of Example 1 was changed to sulfur hexafluoride (SF ₆ ) and trifluoromethane (CHF ₃ ). As a result of evaluating the characteristics, sulfur hexafluoride (SF ₆ ) has a nitrogen gas transmittance of 23 ×.
10 ⁻⁸ mol / (m ² · Pa · sec), and the transmission coefficient ratio α is 48, and trifluoromethane (CH
F ₃ ), the nitrogen gas transmittance is 23 × 10 ⁻⁸ m
ol / (m ² · Pa · sec), and the transmission coefficient ratio α was 32.

[0088]

As described above in detail, according to the PF gas separation filter of the present invention, since it is made of an amorphous composite oxide containing Si and Zr, it has excellent corrosion resistance, heat resistance and water resistance. A PF gas separation filter can be manufactured.

Further, according to the method for producing a PF gas separation filter of the present invention, since a trialkoxysilane having an organic functional group is contained as an alkoxide of silicon, a pore skeleton of a desired size can be formed during sol formation. Can,
By heat-treating this at a predetermined temperature, fine pores having a pore size of a desired size on the order of Å can be left, and PF gas and a specific gas having a smaller molecular diameter than PF gas are separated. It can be concentrated.

[Brief description of the drawings]

FIG. 1 is a partially enlarged sectional view of a PF gas separation filter of the present invention.

FIG. 2 is a partially enlarged view of a separation membrane in the PF gas separation filter of the present invention.

FIG. 3 shows a P having a PF gas separation filter of the present invention incorporated therein.
It is an outline sectional view of an F gas separation device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Perfluoro compound gas separation filter 2 Porous support 3 Separation membrane 4 Intermediate layer 5 Pore

 ──────────────────────────────────────────────────続 き Continued on front page F term (reference) 4D006 GA41 HA27 JA25C KE02P KE03P KE07P KE08P KE12P KE13P KE16R MA02 MA07 MA22 MA24 MA31 MA33 MA40 MB03 MB04 MB15 MB19 MC03X NA10 NA39 NA46 NA50 NA63 PA01 PA02 PB19 PB63 P

Claims (7)

[Claims] (1) at least one surface of a porous support,
A separation membrane made of an amorphous oxide containing Si and Zr having a large number of pores is formed by deposition, and one surface of the separation membrane has a molecular diameter larger than that of the perfluoro compound gas and the perfluoro compound. A perfluoro compound gas separation filter capable of contacting a mixed gas containing a small specific gas and selectively permeating the specific gas to the other surface of the separation membrane to separate the perfluoro compound gas. 2. The perfluoro compound gas separation filter according to claim 1, wherein said amorphous oxide containing Si and Zr has an average pore diameter of 2.5 to 10 °. 3. The nitrogen gas transmittance from normal temperature to 350 ° C. is 1 × 10 ⁻⁸ mol / (m ² · Pa · sec) or more.
3. The perfluoro compound gas separation filter according to claim 1, wherein a transmission coefficient ratio (N ₂ / PF) between nitrogen gas (N ₂ ) and perfluoro compound gas (PF) is 4 or more. 4. An atomic ratio (Zr / Sr) of said Si and said Zr.
The perfluoro compound gas separation filter according to any one of claims 1 to 3, wherein i) has a ratio of 0.01 to 0.5. 5. A step of preparing a composite alkoxide by mixing an alkoxide of silicon and an alkoxide of zirconium in an alcohol solvent; a step of preparing a precursor sol by hydrolyzing the composite alkoxide; Coating on at least one surface of the porous support, drying, and firing at a temperature of 350 to 700 ° C. 6. The silicon alkoxide is a tetraalkoxysilane, and the general formula is The method for producing a perfluoro compound gas separation filter according to claim 5, wherein the mixture is a mixture of another alkoxysilane having an organic functional group represented by the following formula: 7. The content of the other alkoxysilane in the total amount of the silicon alkoxide is 3 to 50 mol%.
The method for producing a perfluoro compound gas separation filter according to claim 6, wherein: