JP4668043B2 - Method for manufacturing helium separator - Google Patents

Description

  The present invention relates to a method for producing a helium separator having excellent heat resistance and excellent helium permeability and selectivity.

In recent years, materials (separation membranes) and methods for selectively separating these gases from a mixed gas containing a gas having a small molecular diameter such as helium and hydrogen have been studied.
As a helium separation material, a separation membrane made of a polymer is known, and Patent Document 1 discloses a gas separation membrane made of a carbon membrane containing silver or copper. Patent Document 2 discloses a polymer obtained by hydrolysis and polycondensation of a composition comprising a polyether copolymer having a specific structure and a polyfunctional alkoxysilane such as tetraalkoxysilane or trialkoxysilane. A type of gas separation membrane is disclosed.
JP 2003-53167 A JP 2005-74317 A

A film made of a polymer has a problem that gas permeability is not sufficient, and a shape cannot be maintained in a high temperature range of 200 ° C. or more, and cannot be used.
Therefore, a gas separation material made of an inorganic material has been studied, and a gas separation material having pores smaller than the molecular diameter of hydrogen, that is, having a pore size controlled on the order of angstroms and having both excellent permeability and selectivity. It has been demanded.
An object of the present invention is to provide a method for producing a helium separator having excellent heat resistance and excellent helium permeability and selectivity.

As a result of intensive studies to solve the above problems, the present inventors have found that the surface layer of the porous substrate made of an inorganic material (the surface of the substrate and the inner wall surface of the communication hole in the vicinity of the substrate surface) In a helium separator comprising a film containing a crystalline substance and a film containing a crystalline substance stacked on the film, particularly on the film in the communication hole, the film containing the crystalline substance is surrounded as an inner wall The inventors have found that the pores with small molecular diameters are excellent in helium permeability and selectivity, and have completed the present invention.
That is, the gist of the present invention is as follows.
1. A coating film forming step of forming a coating film by infiltrating at least the communication hole of a substrate having a communicating hole and made of an inorganic material with a composition for forming an amorphous substance, and heat-treating the substrate containing the coating film Then, an amorphous substance-containing film forming step for forming an amorphous substance-containing film containing an amorphous substance in the communication hole, and a crystalline substance is generated by a chemical reaction in the heat-treated communication hole. the gas material is heated by supplying perform chemical vapor phase synthesis, the amorphous to the surface of the material-containing film, helium separation material, characterized in that it comprises a crystalline material deposition step of Ru is deposited crystalline substance Manufacturing method.
2. 2. The method for producing a helium separator according to 1 above, wherein the composition for forming an amorphous substance contains at least one selected from the group consisting of polycarbosilane, polysilane, polysilazane, and polycarbosilazane.
3. Inorganic material constituting the _substrate, Al ₂ O 3, ZrO _2, mullite, cordierite, AlN, according to the above 1 or 2 is at least one selected from the group of _Si 3 _{N 4} and SiC A method for producing a helium separator.
4). 4. The method for producing a helium separator according to any one of 1 to 3 , wherein the communication hole of the substrate has an average diameter of 5 to 200 nm.
5. 5. The method for producing a helium separator according to any one of 1 to 4 above, wherein a heat treatment temperature in the amorphous substance-containing film forming step is 600 to 1,500 ° C.
6). 6. The method for producing a helium separator according to any one of 1 to 5, wherein the chemical vapor synthesis in the crystalline material deposition step includes a step of heating in the presence of a silicon compound gas and a carbon compound gas.
7). 7. The method for producing a helium separator according to 6 above, wherein the chemical vapor synthesis includes a step of heating while introducing and exhausting a gas of a silicon compound and a gas of a carbon compound.
8). 8. The method for producing a helium separator according to 6 or 7 , wherein the silicon compound is at least one selected from the group consisting of monosilane, disilane, and dichlorosilane.
9. 9. The method for producing a helium separator according to any one of 6 to 8, wherein the carbon compound is at least one selected from the group consisting of acetylene, methane, ethane, propane, butane, pentane, methyl chloride, and vinyl chloride. .

According to the helium separator obtained from the production method of the present invention, it has the above-mentioned configuration, and has a good shape retention in a high temperature range of 200 ° C. or higher, preferably 400 ° C. or higher, more preferably 500 ° C. or higher Long life and excellent helium permeability and selectivity.
Further, according to the method for producing a helium separator of the present invention, a helium separator having excellent heat resistance and excellent helium permeability and selectivity can be easily produced. In particular, an amorphous material-containing film containing an amorphous material and a crystalline material-containing film containing a crystalline material, which are easily and efficiently controlled in film thickness, can be formed. As a result, only helium can be formed. Can be formed.

1. Helium separator
The helium separator obtained in “2. Manufacturing method of helium separator” described below will be described first.
The helium separator is composed of a base body 11 having communication holes and made of an inorganic material, and an amorphous substance-containing film 12 (hereinafter referred to as a film [A]) that covers the surface layer of the base body 11 and contains an amorphous substance. And a crystalline substance-containing film 13 (hereinafter also referred to as a film [B]) disposed on the surface of the amorphous substance-containing film [A] 12 inscribed in the communication hole and containing a crystalline substance. And the pores 14 surrounded by the crystalline substance-containing film [B] 13 (see FIG. 1). The pores 14 are surrounded by the membrane [B] 13 by sequentially laminating the membrane [A] 12 and the membrane [B] 13 on the inner wall of the communication hole. That is, the pore 14 has a reduced inner diameter (pore diameter) of the communication hole, and the inner diameter is longer than the helium molecular diameter and shorter than the hydrogen molecular diameter. Therefore, by using the helium separator, the mixed gas containing helium is separated into helium that passes through the pores 14 and other gas that does not pass through the pores 14.
In the present invention, the “surface layer of the substrate” means both the surface of the substrate and the inner wall surface of the communication hole in the vicinity of the substrate surface. Specifically, the surface of the substrate and the interior of the substrate are about 5 μm. It means both parts up to the depth. “Amorphous” and “crystalline” mean that the crystallinity measured by X-ray diffraction is less than 40% and 60% or more, respectively.

1-1. Substrate This substrate has pores penetrating in a linear or network form from one surface to the other surface, that is, a communication hole, and if it is made of an inorganic material, its structure, shape, size, etc. There is no particular limitation. The communication hole may be a single through hole, or a plurality of through holes may be regularly or irregularly continuous.
The substrate is preferably a porous body, and may be manufactured from an inorganic material, or may be manufactured from an organic material (polymer, organometallic compound, polysaccharide, etc.). Therefore, examples of the constituent material of the substrate include an aluminum compound, a silicon compound, a zirconium compound, and a titanium compound. These may be any of oxides, nitrides and carbides.

The aluminum compound, alumina _{(Al 2 O} 3), mullite _{(3Al 2 O 3 · 2SiO 2} ), cordierite _{(2MgO · 2Al 2 O 3 ·} 5SiO 2), aluminum nitride (AlN) and the like.
Examples of the silicon compound include silica (SiO ₂ ), SiOC, silicon nitride (Si ₃ N ₄ ) silicon carbide (SiC), SiCN, SiBCN, sialon (SiAlON), and the like.
Examples of the zirconium compound include zirconia (ZrO ₂ ) and zirconium boride (ZrB ₂ ).
Examples of the titanium compound include titania (TiO ₂ ) and aluminum titanate (Al ₂ O ₃ · TiO ₂ ).
Among these, Al ₂ O ₃ , mullite, cordierite, AlN, Si ₃ N ₄ , SiC and ZrO ₂ are preferable from the viewpoint of heat resistance.

  The substrate may be a single structure made of only one kind of the inorganic material or a laminate thereof. Moreover, the single structure containing 2 or more types of inorganic materials may be sufficient, and the laminated body may be sufficient. Furthermore, a laminated body formed by laminating structures made of different inorganic materials may be used.

The shape of the substrate is selected according to the purpose, application, etc., but is a lump (polyhedron, sphere, etc.), plate (flat plate, curved plate, etc.), cylinder (cylinder, square tube, etc.), semi-cylinder, It can be a rod or the like.
Further, the size of the substrate is also selected according to the purpose and application. In particular, the thickness relating to the separation of the mixed gas is preferably 150 μm or more.
The shape and size of the helium separation material are reflected in the shape and size of the substrate and are substantially the same.

  As the substrate, a commercially available porous body may be used, or a substrate produced by a known method disclosed in JP 2000-8193 A or the like may be used.

1-2. Amorphous substance-containing film [A]
This film [A] is a film that covers the surface layer of the substrate and contains an amorphous substance. Therefore, in the film [A], the film on the substrate surface and the film inscribed in the communication hole in the vicinity of the substrate surface (along the inner peripheral surface of the communication hole) are continuous.

The film [A] is a film that normally contains an amorphous substance in an amount of 60 to 100% by mass. A crystalline material may be included.
As said amorphous substance, an amorphous inorganic substance is preferable and a silicon compound, an aluminum compound, a zirconium compound, a titanium compound etc. are mentioned. These may be any of oxides, nitrides and carbides, and the compounds exemplified as the constituent material of the substrate can be used. In _{particular, SiO 2, SiOC, SiC,} SiCN and SiBCN are preferred.
Examples of the crystalline substance include crystallized oxides, nitrides, and carbides of the above silicon compounds, aluminum compounds, zirconium compounds, titanium compounds, and the like.

  The membrane [A] may be a membrane having mesopores and / or micropores, or a solid membrane. In the case of mesopores and micropores, a skeleton having the above amorphous substance as a main component is usually provided.

  The average thickness of the film [A] inscribed in the communication hole is preferably 1.5 to 100 nm, more preferably 1.8 to 50 nm, and further preferably 2 to 30 nm. If this thickness is too large, the gas permeation rate tends to decrease. On the other hand, if it is too small, defects tend to be generated in the film.

The embodiment of the film [A] is shown in FIGS. 2 and 3 using sectional views. FIG. 2 is a schematic view showing an example of a state in which the film [A] 12 covers the surface layer of the base body 11 (hereinafter referred to as “laminated body”), and the inner diameter of adjacent communication holes of the base body 11 is shown. In different cases, the film on the substrate surface and the film inscribed in the communication hole in the vicinity of the substrate surface are continuous.
FIG. 3 is a schematic cross-sectional view showing another example of a laminate in which the film [A] 12 covers the surface layer of the base 11. When the inner diameter of the communication hole of the base 11 is smaller, the communication is performed. The holes are filled with the constituent material of the membrane [A] and closed. In this case, depending on the pore structure of the membrane [A], only a specific gas having a small molecular diameter may permeate through the packed portion and have gas separation ability. On the other hand, when the membrane [A] is solid, it becomes a part of the substrate 11 and can improve the mechanical strength, thermal stability (heat resistance) and the like of the helium separator.
In the schematic view of FIG. 2 and the like, the communication hole of the base 11 is shown in a direction perpendicular to the base 11, but may be communicated in an oblique direction. The same applies to the other drawings.

  The method for forming the film [A] is not particularly limited. For example, after the material that can form an amorphous substance is applied to the surface layer of the substrate, the substrate is subjected to heat treatment at a temperature at which the substrate is not deformed or altered. Etc. A detailed method will be described later.

1-3. Crystalline material-containing film [B]
This film [B] is a film that is disposed on the surface of the amorphous substance-containing film [A] inscribed in the communication hole in the surface layer and contains a crystalline substance.

The film [B] is a film that normally contains 60 to 100% by mass of a crystalline substance made of single crystal and / or polycrystal. An amorphous material may be included.
Examples of the crystalline substance include silicon compounds, aluminum compounds, titanium compounds, zirconium compounds, and the like. These may be any of oxides, nitrides and carbides.

Examples of the silicon compound include silicon carbide, silicon nitride, and sialon.
Examples of the aluminum compound include alumina, aluminum nitride, mullite and the like.
Examples of the titanium compound include aluminum titanate, titanium carbide, and titanium nitride.
Examples of the zirconium compound include zirconia and zirconium boride.
Of these, SiC, Al ₂ O ₃ , zirconia and the like are preferable, and SiC is particularly preferable.

  As described above, the film [B] contains 60% by mass or more of a crystalline substance, and is usually a solid dense film, so that a gas having a large molecular diameter exceeding 0.288 nm is difficult to permeate.

  The average thickness of the film [B] is preferably 0.5 to 4 nm, more preferably 0.6 to 3.5 nm, and still more preferably 0.7 to 3 nm. If this average thickness is too small, the thermal stability of the film [B] may be lowered. As shown in FIG. 1, the pores 14 for helium separation are surrounded by the membrane [B] 13, and the average inner diameter is usually 0.261 to 0.288 nm, preferably Since it is 0.270-0.280 nm, the thickness of the said film [B] is adjusted in the formation, and becomes the said range.

The membrane [B] may be at any position on the surface of the membrane [A] in the communication hole, may be in the vicinity of the outermost surface of the substrate (see FIG. 4), or may be slightly inside. However, it may be the entire surface of the film [A] (see FIG. 6). The film [B] may be on the surface of the film [A] on the surface of the substrate 11 (not shown).
Embodiments of the film [B] are shown in FIGS. 4, 5 and 6 using cross-sectional views. FIG. 4 is a schematic view showing that the film [B] 13 is formed in the vicinity of the outermost surface of the substrate on the surface of the film [A] 12 in the communication hole. FIG. 5 is a schematic view showing that the film [B] 13 is formed slightly inside the surface of the film [A] 12 in the communication hole from the surface of the substrate.
FIG. 6 is a schematic view showing that the film [B] 13 is formed on the entire surface of the film [A] 12 in the communication hole.
4, 5, and 6, reference numeral 131 indicates a state in which the constituent material of the film [B] is filled in the communication hole surrounded by the film [A] 12 in the communication hole. This filling part 131 has almost no gas separation ability.

  The method for forming the film [B] is not particularly limited. For example, a method of introducing a gas capable of forming a crystalline substance into a heated communication hole of the substrate on which the film [A] is formed; Examples include a method in which a material capable of forming a porous material is applied to the surface of the film [A] in the communication hole and then heat-treated at a temperature at which the laminate is not deformed or altered. A detailed method will be described later.

As described above, the helium separation material obtained by the production method of the present invention is laminated on the substrate 11 having communication holes, at least the film [A] 12 inscribed in the communication holes, and the surface of the film [A] 12. The membrane [B] 13 is provided, and the pores 14 surrounded by the membrane [B] 13 exhibit the gas separation function by having the preferred pore diameter.

2. Method for Producing Helium Separating Material The method for producing a helium separating material according to the present invention is a method in which a composition for forming an amorphous substance is infiltrated into at least the communicating hole of a substrate having a communicating hole and made of an inorganic material. A coating film forming process for forming a film, and a substrate containing the coating film is heat-treated to form an amorphous substance-containing film (film [A]) containing an amorphous substance in the communication hole. In the film forming step, a gas raw material that generates a crystalline substance by a chemical reaction is supplied into the heat-treated communication hole and heated to perform chemical vapor phase synthesis, and the amorphous substance-containing film (film [A the surface of]), characterized in that it comprises a crystalline material deposition step of Ru is deposited crystalline substance.

If the substrate has pores penetrating from one surface to the other in a linear or mesh shape, that is, communicating holes, and made of an inorganic material, its structure, shape, size, etc. It is not limited. For these, both may be the same as described in the above "1. helium separation material". In particular, the constituent material of the substrate is preferably Al ₂ O ₃ , mullite, cordierite, AlN, Si ₃ N ₄ , SiC and ZrO ₂ . Moreover, the said base | substrate has preferable uniform thickness, and is a plate shape, a cylinder shape, etc., Comprising: The thing whose thickness or thickness is 150-1,000 micrometers is preferable.
The average pore diameter of the communication holes is preferably 5 to 200 nm, more preferably 5 to 150 nm, and still more preferably 6 to 100 nm.

As the substrate, a commercially available product or a product obtained by a known method can be used as described above. In addition, while the average pore diameter of the communication holes is in the preferred range, if the distribution is wide, or if the average pore diameter is too large exceeding 200 nm, the mechanical strength of the substrate may not be sufficient, Thereafter, deformation or the like may occur when the film [A] or the like is formed. Therefore, in order to reinforce the substrate, a precursor composition that is the same as or different from the constituent material of the substrate is previously deposited on the surface of the substrate or the inner wall of the communication hole before forming the film [A]. It may be allowed (see FIG. 8). When it is deposited on the inner wall of the communication hole, the average pore diameter can be narrowed within the above preferred range, and the subsequent steps can be carried out efficiently. FIG. 8 is a schematic cross-sectional view showing an example of a reinforced substrate, which includes a substrate support 111 and a reinforcement layer 112 that covers the surface of the substrate support 111, and is surrounded by the reinforcement layer. The communication hole 15 is provided.
Examples of the reinforcing method include a method in which the precursor composition is infiltrated into the surface of the substrate or the inner wall surface of the communication hole by a dipping method, a spray method, a spin method or the like to form a coating film, and then heat-treated. It is done. In addition, what was obtained by the sol gel method etc. can be used for this precursor composition.

In the present invention, the coating film forming step, a substrate made of and inorganic material has a communication hole, to form a coating film to penetrate the at least該連the hole. Specifically, a dipping method, a spray method, a spin method, or the like is applied using the following composition for forming an amorphous substance. By these methods, a coating film is usually formed on the surface of the substrate and the entire inner wall of the communication hole.

  The composition for forming an amorphous material is preferably a composition capable of forming an amorphous material by heat treatment or the like, and one or more of a silicon compound, an aluminum compound, a zirconium compound, a titanium compound and the like are in an amorphous state. What is formed is preferred.

Examples of the composition that forms an amorphous silicon compound include a solution or dispersion containing a silicon-containing polymer; a solution of an alkoxysilane compound; a composition containing a silica sol such as sodium silicate, water glass, or colloidal silica. It is done. Of these, compositions containing silicon-containing polymers are preferred.
The silicon-containing polymer is preferably a compound mainly containing silicon atoms and carbon atoms. Other examples include an oxygen atom, a hydrogen atom, a nitrogen atom, and a boron atom.
Examples of the silicon-containing polymer include polycarbosilane, polysilane, polysilazane, polycarbosilazane and the like. These modifying compounds (some are exemplified below) can also be used. The number average molecular weight of these polymer compounds is usually 500 to 100,000. These can be used alone or in combination of two or more.

Among the silicon-containing polymers, polycarbosilane is a polymer compound containing units represented by the following general formulas (1) to (3) alone or in combination of two or more.
[Wherein, R ₁ represents an alkyl group having 1 to 10 carbon atoms. ]
[R ₁ and R ₂ may be the same or different and each represents an alkyl group having 1 to 10 carbon atoms. ]

  Examples of the polysilane include poly (dimethylsilane), poly (diethylsilane), poly (di-n-propylsilane), poly (di-n-butylsilane), poly (di-n-hexylsilane), and poly (methylphenyl). Silane), poly (ethylphenylsilane), poly (n-propylphenylsilane), poly (diphenylsilane), poly (methylphenylsilane-co-dimethylsilane), poly (methylphenylsilane-co-di-n-hexyl) Silane) and the like.

The polysilazane is a polymer compound containing units represented by the following general formulas (4) and (5) alone or in combination.
Wherein, _{R 3} represents an alkyl group having 1 to 3 carbon atoms. ]

In the units represented by the general formulas (4) and (5), a high molecular compound in which one H (hydrogen atom) of —SiH ₂ — is substituted with an alkoxy group having 1 to 3 carbon atoms is used as a modified compound Can be used as

  A composition containing the silicon-containing polymer and / or a modified compound thereof and a metal alkoxide containing aluminum, titanium, or the like can also be used. Examples of the modifying compound include polysilane having a hydroxyl group.

  The silicon-containing polymer and / or its modified compound is usually used by dissolving in a fast-drying solvent such as benzene, toluene, xylene, ethylbenzene, diethylbenzene, cyclohexane, cyclohexene and the like. A preferable concentration for forming a uniform coating film is 0.1 to 5% by mass, more preferably 0.25 to 2.5% by mass, and still more preferably 0.5 to 1.5% by mass. . If this concentration is too low, pinholes may be generated on the surface of the formed film [A]. On the other hand, if the concentration is too high, the thickness of the film [A] exceeds the above preferred range, and cracks are likely to occur. In either case, good gas separation performance will be affected.

  The silicon-containing polymer solution is preferably used in the absence of oxygen and water vapor, and is preferably used in an inert gas atmosphere such as argon gas.

  Examples of the composition that forms an amorphous aluminum compound include a solution containing an aluminum-containing alkoxide; a solution or dispersion of sodium aluminate, aluminum sulfate, alumina sol, or the like.

Examples of the composition for forming an amorphous zirconium compound include a composition containing a solution of zirconium alkoxide, zirconium oxychloride, zirconium chloride and the like.
Moreover, as a composition which forms an amorphous titanium compound, the composition containing the solution of titanium alkoxide; titanium chloride, dialkylamino titanium, etc. is mentioned.

As described above, the coating film is formed on almost the entire surface reflecting the unevenness of the substrate by this coating film forming process. The material forming composition is filled to form a continuous coating film.
The thickness of the coating film is appropriately adjusted depending on the pore diameter of the communicating holes of the substrate, the type and concentration of the amorphous substance forming composition used, and the like.

  After the coating film forming step, the coating film is usually formed to a thickness of about 5 to 100 nm by drying the coating film. Thereafter, by proceeding to the amorphous substance-containing film forming step, the substrate including the coating is heat-treated to form the amorphous substance-containing film [A].

  The heat treatment conditions in the amorphous substance-containing film forming step are such that the heating temperature is preferably 600 to 1,500 ° C., more preferably 625 to 1,000 in an atmosphere of argon gas, nitrogen gas or the like under atmospheric pressure. ° C, more preferably 650 to 800 ° C. By performing heat treatment in this temperature range, the decomposition of the raw material proceeds smoothly (having an efficient film forming speed), and as a result, a uniform amorphous substance-containing film can be obtained. If the temperature is too low, the generation of amorphous material may be incomplete. On the other hand, if the temperature is too high, a large amount of crystalline material may be generated. In addition, although heating time, a temperature increase rate, etc. are selected suitably, heating time is 1 to 5 hours normally.

When the coating film before the heat treatment contains at least one of polycarbosilane, polysilane, polysilazane, polycarbosilazane and these modified compounds, it is included in the film [A] after the amorphous substance-containing film forming step. The amorphous material is usually at least one of SiO ₂ , SiOC, SiC and SiCN.
In addition, when the coating film contains one or more of trialkylboron, dialkylaminoboron and the like, the amorphous substance contained in the film [A] after the amorphous substance-containing film forming step is usually SiBCN.
In either case, depending on the heat treatment conditions, the film [A] may contain a crystalline substance.

The film [A] obtained by the amorphous substance-containing film forming step is preferably inscribed in the communication hole of the substrate, and the coating film is formed on almost the entire surface of the substrate. Similarly, the film [A] 12 is formed on almost the entire surface of the substrate 11 including the surface layer of the substrate (see FIG. 2), and is a laminated body having no helium permeation path other than the remaining communication holes. be able to. When this route is present, a behavior called Knudsen diffusion is exhibited during molecular sieving, and the desired gas separation performance may not be obtained.
In addition, when the internal diameter of the communication hole of the base was smaller, and the communication hole was filled with the above-mentioned composition for forming an amorphous substance, the communication hole was filled with the amorphous substance and closed by heat treatment. A state is reached (see FIG. 3).

After the amorphous material containing film-forming step, by advancing the crystalline material deposition step, the surface of the membrane [A] of the laminate Ru depositing a crystalline material.

In this crystalline material deposition step, a gas capable of forming a crystalline material is introduced into a heated communication hole of the laminate (chemical vapor phase synthesis ) . For reference, as another method, after a material capable of forming a crystalline substance is applied to the surface of the film [A] in the communication hole, a heat treatment is performed at a temperature at which the stacked body is not deformed or altered; the laminate in a state immersed in a solution containing a possible form crystalline substance material, there Ru and a method of electrically processing.

In the crystalline material deposition step according to the present invention, a gaseous material that generates a crystalline material by a chemical reaction is supplied to at least the communication holes of the stacked body placed in a sealed reaction system, and the film [A] is formed. A film containing a crystalline material is deposited on the surface.

The gaseous material is usually a gas of a compound composed of an element constituting a crystalline material (oxide, nitride, carbide, etc.) to be formed. In particular, it is preferable to select a gas raw material from which a crystalline substance is generated by a thermochemical reaction.
Two or more kinds of gas raw materials are preferably used, and at least a gas of a silicon compound and a gas of a carbon compound are preferably used.
Examples of the silicon compound include monosilane, disilane, and dichlorosilane. These can be used alone or in combination of two or more.
The carbon compound is not particularly limited as long as it is a gas at room temperature, and examples thereof include acetylene, methane, ethane, propane, butane, pentane, methyl chloride, and vinyl chloride. These can be used alone or in combination of two or more.

In the chemical vapor synthesis, the gaseous raw material may be heated in a state in which the reaction system in which the laminated body is placed is filled, but preferably, one side of the laminated body ( In a state in which the surface layer side) and the other side are partitioned, the stack is introduced using an apparatus including at least a means for supplying a first gas and a means for supplying a second gas, and then heated. The body is forcibly passed from one side to the other side in the body communication hole. In order to “forcibly pass” the gaseous material, an exhaust means such as a pump may be applied to the other side. Since the helium separation greatly contributes to the inner diameter of the pores surrounded by the film [B] formed on the film [A] in the communication hole, the gas source intensively passes through the communication hole of the laminate. Thus, a dense film [B] can be formed.
In addition, the introduction of the gas raw material to the reaction system may be performed by supplying the above gases individually or by using a gas that does not participate in a gas phase reaction such as hydrogen gas as a carrier gas. Further, the above gases may be individually introduced into the reaction system, or may be introduced into the reaction system after being mixed before being introduced into the reaction system. The gas introduction rate and the exhaust rate from the reaction system are not particularly limited, but may be introduced continuously or intermittently.

  The heating temperature of the reaction system when introducing the gas raw material is preferably 600 to 800 ° C, more preferably 650 to 780 ° C, and further preferably 680 to 750 ° C. If this temperature is too low, the gas phase reaction may not proceed. On the other hand, if it is too high, the film formation rate may increase and the gas permeation rate may decrease.

  In the chemical vapor phase synthesis, a film containing a crystallized substance composed of a single crystal and / or a polycrystal can be formed by a reaction by introducing a gas raw material for 0.5 to 4 seconds. Therefore, in order to form a dense film [B] with a high content of crystallized material on the film [A] in the communication hole, the fine diameter is 0.261 to 0.288 nm. In order to form holes, it is preferable to repeatedly introduce the gas raw material. When the preferred apparatus is used, by repeating this, the inner diameter due to deposition of the crystalline substance on the inner wall of the communication hole is reduced, the flow of the gas raw material is not smooth, and pores having the preferred average diameter can be obtained. it can.

  The film [B] obtained by applying the above chemical vapor synthesis and forcibly passing the gas raw material into the communication hole of the heated laminate may be formed on the surface of the laminate. However, most of the gas raw material reacts in the communication hole and is formed on the surface of the film [A] in the communication hole (see FIG. 6). In addition, when the internal diameter of the said communicating hole is as small as 0.3 nm or less, it may be obstruct | occluded with the product by reaction of a gaseous raw material (code | symbol 131 of FIG. 6).

The film [B] obtained by the crystalline material deposition step can form pores excellent in permeability to only helium, and the substrate, the film [A] and the film [B] are inorganic. Since it is made of a material, a helium separator excellent in heat resistance and durability can be obtained at a temperature of 100 ° C. or higher, preferably 200 ° C. or higher as well as 100 ° C. or lower.

The helium separator obtained by the production method of the present invention is useful as a molecular sieving film that has excellent heat resistance and separates helium from a mixed gas containing helium. In particular, when separating helium and carbon monoxide at 600 ° C., the permeability coefficient ratio (He / CO) can be preferably 15 or more, more preferably 25 or more, and still more preferably 35 or more. In the case of separation of helium and hydrogen, the permeation coefficient ratio (He / H ₂ ) is preferably 2 or more, more preferably 2.5 or more, and further preferably 3 or more.
As described above, in the crystalline material deposition step, the film thickness of the film [B] can be adjusted, so that the inner diameter of the pore is larger than the molecular diameter of hydrogen, for example, 0. When the film [B] is formed to have a thickness of 29 to 0.32 nm, it can be used as a hydrogen gas separation material.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to such examples unless it exceeds the gist of the present invention. In the following description, “%” is based on mass unless otherwise specified.
Example 1
Porous tubular body 111 (inner diameter 1.8 mm, outer diameter 2.6 mm, and length) made of α-Al ₂ O ₃ and having pores (average pore diameter 100 nm) communicating in a mesh shape between the inner wall and the outer wall 85 mm) both end faces are made of α-Al ₂ O ₃ , solid tube 21 having the same inner diameter and outer diameter, and α-Al ₂ O ₃ , the same inner diameter and outer diameter, and the bottom face Was sealed with each end face of the solid bottomed tube 22 having a concave surface to obtain a composite 2 (see FIG. 7). That is, the composite 2 includes a solid tube 21, a porous tubular body 111, and a solid bottomed tube 22 in this order, and a glass sealing portion 23 for bringing the end faces of the tubes into close contact with each other. Is provided.
Thereafter, the composite 2 was immersed in a boehmite sol (PVA concentration; 3.5%) prepared by a sol-gel method for 10 seconds. Next, this sol was dried and heat-treated at 800 ° C. for 3 hours in an argon gas atmosphere, and a film made of γ-Al ₂ O ₃ was formed on the entire surface of the composite 2 (including the inner wall surface of the pores of the tubular body 111). Formed. This operation is repeated again, and a base portion (hereinafter also referred to as “base”) 11 having a tubular body 111 and a γ-Al ₂ O ₃ film 112 covering the entire surface of the tubular body 111 (see FIG. 8). A composite 3 with a substrate (not shown) was obtained. The average pore diameter of the substrate 11 was 10 nm. FIG. 8 is a view showing a base 11 constituting the composite 3 with a base, and is a schematic view showing a partial cross section when the base 11 is broken at a communicating hole portion. It shows that the γ-Al ₂ O ₃ film 112 is formed on the surface of the tubular body 111.

Next, the composite with substrate 3 was immersed in a xylene solution (concentration 1%) of polycarbosilane (number average molecular weight; 10,700) prepared in a glove box in an argon gas atmosphere (FIG. 10). reference). The xylene solution was infiltrated from the outside of the composite 3 with a substrate by capillary action.
Thereafter, the xylene solution is dried and heat-treated at 800 ° C. for 1 hour in an argon gas atmosphere, and a film 12 containing amorphous SiOC on the entire surface of the substrate-equipped composite 3 (film on the surface of the substrate-equipped complex 3) Thickness 130 nm, the film thickness in the communication hole is considered to be 2.5 to 4 nm, hereinafter also referred to as “SiOC film”), and the composite 5 with the SiOC film including the tubular body 4 with the SiOC film is obtained. It was. FIG. 11 is a cross-sectional image (by an electron microscope) of the tubular body 4 with the SiOC film when the tubular body 111 with the SiOC film is broken, and the SiOC film 12 is formed on the surface of the γ-Al ₂ O ₃ film 112. Indicates that

Next, the composite 5 with the SiOC film was set in the furnace 7 of the CVD apparatus (see FIG. 12), and preheated at 725 ° C. for 20 minutes in a hydrogen gas atmosphere. After the temperature of the composite 5 with the SiOC film reaches a constant temperature, a mixed gas composed of the following raw material gases [1] to [3] is intermittently introduced into the furnace, and the internal pressure in the apparatus due to the introduction of the mixed gas is reduced. The silicon carbide polycrystal is deposited on the surface of the SiOC film 12 in the pores of the tubular body 4 with the SiOC film until the pressure rises to near atmospheric pressure (the film thickness in the communication hole is considered to be 0.7 to 2.5 nm). ), A helium separator 1 was obtained. A fracture image is shown in FIG.
The source gas [1] (carrier gas) is hydrogen gas, the source gas [2] is a mixed gas composed of hydrogen gas and SiH ₂ Cl ₂ gas (SiH ₂ Cl ₂ concentration: 1% by volume), and the source gas [3 ], A mixed gas composed of hydrogen gas and acetylene gas (acetylene concentration: 1% by volume) was used. The amount of each source gas introduced was 1 sccm, 0.5 sccm, and 0.5 sccm in the order of source gases [1] to [3], and each source gas was mixed before being introduced into the furnace. Moreover, the mixed gas which consists of source gas [1]-[3] was introduce | transduced by repetition of introduction time 2 second and interval 2 second, and this was repeated 3,500 times.
In the image of FIG. 13, the film 13 made of polycrystalline silicon carbide cannot be distinguished because it is fine. However, the polycrystalline silicon carbide exists in the pores of the tubular body 4 with the SiOC film by X-ray measurement. It was confirmed.

Using the helium separation material obtained above, a single component gas permeation test at 600 ° C. was performed by the gas permeation test apparatus shown in FIG. 14 based on the constant volume pressure change method. First, the flow rate of gas molecules is quantified by the pressure change in the buffer tank installed in the permeation side line where the pressure is reduced. A stop valve installed between the vacuum pump and the buffer tank after flowing the atmospheric pressure supply gas into the permeation cell holding the helium separator at 500 cc / min and reducing the pressure in the buffer tank to 4 Torr by the vacuum pump. closed, the tank by the pressure gauge P ₂ measured the time until the boosted to 8 Torr. The types of single component gas used are helium gas (He), hydrogen gas (H ₂ ), and carbon monoxide gas (CO). Permeability was measured for gas that permeates under unit area and unit pressure difference. The unit is mol / m ² · s · Pa. Further, the permeability values He / H ₂ and He / CO, which are ratios of the transmittances, were obtained as indices representing the gas separation performance using the values of the transmittances of the respective gases. The obtained helium gas permeability, hydrogen gas permeability, and permeability coefficient ratio are shown in Table 1.

Example 2
Using the composite 3 with a base body obtained in Example 1, a helium gas separation material was obtained in the following manner.
The composite 3 with a base was immersed in a xylene solution (concentration 0.8%) of polycarbosilane (number average molecular weight; 10,700) prepared in a glove box under an argon gas atmosphere (see FIG. 10). ). The xylene solution was infiltrated from the outside of the composite 3 with a substrate by capillary action.
Then, this xylene solution was dried and heat-treated in an argon gas atmosphere at 800 ° C. for 1 hour, and a SiOC film was formed on the entire surface of the composite 3 with a substrate. This dipping-drying-heat treatment operation is repeated again, with the SiOC film having the SiOC film 12 having a film thickness of 140 nm on the surface of the substrate-attached composite 3 (the film thickness in the communication hole is considered to be 3 to 4.5 nm). A complex 5 was obtained.

Next, using the same CVD apparatus as in Example 1, a mixed gas consisting of the same raw material gases [1] to [3] is introduced at a repetition time of 2 seconds and an interval of 2 seconds, and this is repeated 3,000 times. Thus, silicon carbide polycrystal was deposited on the surface of the SiOC film 12 in the pores of the tubular body 4 with the SiOC film (the film thickness in the communication hole seems to be 0.6 to 2 nm), and the helium separator 1 was obtained. .
About this helium separation material, it carried out similarly to Example 1, and measured the transmittance | permeability of each gas. The helium gas permeability and permeability coefficient ratio are shown in Table 1.

Example 3
A porous tubular body (inner diameter of 2.0 mm, outer diameter of 2.9 mm, and length of 85 mm) made of α-Al ₂ O ₃ and having pores (average pore diameter of 150 nm) communicated in a network between the inner wall and the outer wall both end surfaces of), in the same manner as in example 1, a tube of solid body consisting of α-Al ₂ O _3, and, to a glass sealed by the end surface of the bottomed tube of solid body consisting of α-Al ₂ O ₃ A composite 2 was obtained.
Thereafter, the composite 2 was immersed in the boehmite sol used in Example 1 for 10 seconds. Next, this sol was dried and heat-treated at 800 ° C. for 3 hours in an argon gas atmosphere to form a film made of γ-Al ₂ O _{3 on} the entire surface of the composite 2. This operation was further repeated twice to obtain a composite 3 with a substrate including a substrate 11 including a tubular body and a γ-Al ₂ O ₃ film covering the entire surface of the tubular body. The average pore diameter of the substrate 11 was 10 nm.

Next, the composite 3 with a substrate was immersed in a xylene solution (concentration 0.5%) of polycarbosilane (number average molecular weight; 10,700) prepared in a glove box in an argon gas atmosphere for 5 seconds ( (See FIG. 10). The xylene solution was infiltrated from the outside of the composite 3 with a substrate by capillary action.
Then, this xylene solution was dried and heat-treated in an argon gas atmosphere at 800 ° C. for 1 hour, and a SiOC film was formed on the entire surface of the composite 3 with a substrate. This immersion-drying-heat treatment operation was further repeated twice. Then, using the xylene solution, the immersion-drying-heat treatment operation was further repeated three times with an immersion time of 10 seconds and a heat treatment temperature of 750 ° C., and a film thickness of 110 nm on the surface of the composite 3 with a substrate (film thickness in the communication hole) The composite 5 with the SiOC film having the SiOC film 12 was obtained.

Next, using the same CVD apparatus as in Example 1, the composite 5 with the SiOC film was set inside the furnace 7 and preheated at 710 ° C. for 20 minutes in a hydrogen gas atmosphere. After the temperature of the composite 5 with the SiOC film reaches a constant temperature, the mixed gas composed of the raw material gases [1] to [3] is intermittently introduced into the furnace, and the SiOC in the pores of the tubular body 4 with the SiOC film is introduced. Silicon carbide polycrystal was deposited on the surface of the film 12 (the film thickness in the communication hole is considered to be 0.5 to 1.8 nm), and the helium separator 1 was obtained.
The amount of each source gas introduced is 1 sccm, 0.4 sccm, and 0.8 sccm in the order of source gases [1] to [3]. Moreover, the mixed gas which consists of source gas [1]-[3] was introduce | transduced by repetition of introduction time 2 second and interval 2 second, and this was repeated 2,800 times.
About this helium separation material, it carried out similarly to Example 1, and measured the transmittance | permeability of each gas. The helium gas permeability and permeability coefficient ratio are shown in Table 1.

As is apparent from the above examples, an amorphous substance containing SiOC is contained on the surface of the base body in which the γ-Al ₂ O ₃ film is formed on the surface of the tubular body made of α-Al ₂ O ₃ and the inner wall of the communication hole. By forming a film and then laminating a crystalline substance-containing film on the amorphous substance-containing film in the communication hole, helium and a gas having a large molecular diameter could be separated.

The helium separator obtained by the production method of the present invention is useful for extraction, separation, etc. of helium from crude helium raw materials such as natural gas, and particularly in a non-oxidizing atmosphere when the sample to be treated is in a heated state. It is suitable when used.

It is the schematic which shows an example of the fracture | rupture surface of the helium separation material obtained by the manufacturing method of this invention. 3 is a schematic cross-sectional view showing an example of a laminate in which an amorphous substance-containing film 12 covers a surface layer of a substrate 11. FIG. FIG. 6 is a schematic cross-sectional view showing another example of a laminate in which an amorphous substance-containing film 12 covers a surface layer of a substrate 11. It is the schematic which shows an example of sectional drawing in the surface layer of the helium separation material obtained by the manufacturing method of this invention. It is the schematic which shows the other example of sectional drawing in the surface layer of the helium separation material obtained by the manufacturing method of this invention. It is the schematic which shows the other example of sectional drawing in the surface layer of the helium separation material obtained by the manufacturing method of this invention. 1 is a schematic perspective view showing a composite 2 produced in Example 1. FIG. In Example 1, 2, and 3, it is the schematic which shows the cross section of the base | substrate 11 reinforced. In Examples 1, 2, and 3, it is the schematic which shows the cross section in which the amorphous substance containing film | membrane 12 was formed in the surface of the base | substrate 11. FIG. FIG. 4 is an explanatory view showing a part of a process for forming an amorphous substance-containing film in Examples 1 and 2. 2 is an image showing a cross section of an amorphous substance-containing film formed on the surface of a substrate in Example 1. It is the schematic which shows the CVD apparatus for forming a crystalline substance containing film | membrane on the surface of an amorphous substance containing film | membrane. 2 is an image showing a cross section of the helium separator obtained in Example 1. FIG. It is a schematic diagram of the gas permeation performance evaluation apparatus based on the constant volume pressure change method.

1; Helium separator 11; Base (base part)
111; Support for substrate (porous tubular body)
112; Reinforcing membrane (γ-Al ₂ O ₃ membrane)
12: Amorphous substance-containing film (SiOC film)
13; Crystalline substance-containing film (silicon carbide polycrystalline film)
131; Crystalline material filling part 14; Pore 15; Communication hole 2; Composite 21; Alumina tube 22; Alumina-bottomed tube 23; Glass sealing part 3; Substrate composite 4; SiOC membrane-attached tubular body 5; Composite with SiOC film 6; Xylene solution 7; Furnace of CVD apparatus.

Claims (9)

A coating film forming step of forming a coating film by infiltrating at least the communication hole of a substrate having a communicating hole and made of an inorganic material with a composition for forming an amorphous substance, and heat-treating the substrate containing the coating film Then, an amorphous substance-containing film forming step for forming an amorphous substance-containing film containing an amorphous substance in the communication hole, and a crystalline substance is generated by a chemical reaction in the heat-treated communication hole. the gas material is heated by supplying perform chemical vapor phase synthesis, the amorphous to the surface of the material-containing film, helium separation material, characterized in that it comprises a crystalline material deposition step of Ru is deposited crystalline substance Manufacturing method. The method for producing a helium separator according to claim 1 , wherein the composition for forming an amorphous substance contains at least one selected from the group consisting of polycarbosilane, polysilane, polysilazane, and polycarbosilazane. Inorganic material constituting the _substrate, Al ₂ O 3, ZrO _2, mullite, cordierite, AlN, according to claim 1 or 2 is at least one selected from the group of _Si 3 _{N 4} and SiC Method for producing a helium separator. The method for producing a helium separator according to any one of claims 1 to 3 , wherein an average diameter of the communication holes of the base is 5 to 200 nm. The method for producing a helium separator according to any one of claims 1 to 4 , wherein a heat treatment temperature in the amorphous substance-containing film forming step is 600 to 1,500 ° C. 6. The method for producing a helium separator according to claim 1, wherein the chemical vapor synthesis in the crystalline material deposition step includes a step of heating in the presence of a silicon compound gas and a carbon compound gas. The method for producing a helium separator according to claim 6 , wherein the chemical vapor synthesis includes a step of heating while introducing and exhausting a gas of a silicon compound and a gas of a carbon compound. The method for producing a helium separator according to claim 6 or 7 , wherein the silicon compound is at least one selected from the group consisting of monosilane, disilane, and dichlorosilane. The helium separator according to any one of claims 6 to 8, wherein the carbon compound is at least one selected from the group consisting of acetylene, methane, ethane, propane, butane, pentane, methyl chloride, and vinyl chloride. Method.