JP2015033688A - Porous silica base body for high-silica zeolite membrane, fluid separation material and method for producing the fluid separation material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a porous silica base body for a high-silica zeolite membrane being excellent in gas permeability, containing no alumina and having a thermal expansion coefficient close to that of the high-silica zeolite membrane, a fluid separation material formed with the high-silica zeolite membrane on the base body and a method for producing the same.SOLUTION: In a porous silica base body 21 for a high-silica zeolite membrane,: the high-silica zeolite membrane 22 is formed on a surface; a porosity is 35-70%; and an average pore diameter is 250-450 nm. In a method for producing a liquid separation material 20,: the porous silica base body 21 for the high-silica zeolite membrane is immersed into a zeolite seed crystal dispersion liquid whose pH value is adjusted to be 4 or less; the base body is pulled up from the dispersion liquid; a seed crystal is coated on the surface of the base body; and then the seed crystal coated on the surface of the base body 21 is secondarily grown by a hydrothermal synthesis method to form the high-silica zeolite membrane 22.

Description

  The present invention relates to a porous silica substrate for a high silica zeolite membrane, a fluid separation material using the substrate, and a method for producing the same.

In recent years, fluid separation materials in which a zeolite membrane is formed on the surface of a porous substrate have been used. Zeolite membranes are known to vary in the size of regular pores depending on their crystal type, and the selectivity of molecules that permeate through the pores varies depending on the molar ratio of the constituent SiO ₂ and Al ₂ O ₃ ( In general, the larger the SiO ₂ / Al ₂ O _{3, the} more lipophilic increases). Among them, the high silica zeolite membrane having a large SiO ₂ / Al ₂ O ₃ has alcohol / water separation, olefin / paraffin separation, hydrocarbon isomer separation, Application to organic matter separation such as aromatic hydrocarbon / aliphatic hydrocarbon separation is expected (see, for example, Patent Documents 1 to 4).

Japanese Patent No. 4494685 Japanese Patent No. 4620065 Japanese Patent No. 4494685 JP 2008-188564 A Japanese Patent No. 4961322 Japanese Patent No. 4304382 Japanese Patent No. 3723888 Japanese Patent No. 4494685

Luc Bousse et al. "Zeta Potential measurement of Ta2O5 and SiO2 thin films", J. et al. Colloid Interface Sci. 147, P22-32, 1991.

Conventionally, alumina and mullite are generally used as a zeolite membrane substrate from the standpoint of availability and price (for example, see Patent Documents 5 and 6). However, if an attempt is made to form a high silica zeolite membrane having a large SiO ₂ / Al ₂ O ₃ molar ratio on the surface of these substrates containing a high concentration of alumina component, the alumina component is eluted from the substrate to the membrane, so SiO ₂ It is known that it is difficult to control the / Al ₂ O ₃ molar ratio to be constant. In addition, in the production of a zeolite membrane that requires a structure-directing agent, it is necessary to burn it at a high temperature after film formation and remove it from the membrane. Since the difference in coefficient is large, cracks may occur in the high silica zeolite membrane when the structure directing agent is burned at a high temperature. As a substrate that does not contain a high concentration alumina component and has a coefficient of thermal expansion close to that of high silica zeolite, Vycor described in Patent Document 7 is known, but Vycol has a small pore diameter and porosity, There is a problem of low permeability. Further, Patent Document 8 discloses a method in which zeolite itself is a porous substrate, but this method involves a complicated substrate manufacturing process.

  The present invention provides a porous silica substrate for a high silica zeolite membrane that has excellent gas permeability, does not contain alumina, and has a thermal expansion coefficient close to that of a high silica zeolite membrane, and fluid separation in which a high silica zeolite membrane is formed on the substrate. It aims at providing material and its manufacturing method.

In order to achieve the above object, the porous silica substrate for high silica zeolite membrane of the present invention comprises:
The porosity is 35% to 70%, and the average pore diameter is 250 nm to 450 nm.

In order to achieve the above object, the fluid separation material of the present invention comprises:
A high silica zeolite membrane having a SiO ₂ / Al ₂ O ₃ molar ratio of 30 or more is formed on a porous silica substrate having a porosity of 35% to 70% and an average pore diameter of 250 nm to 450 nm.

In order to achieve the above object, the fluid separation material of the present invention comprises:
A high silica zeolite membrane not containing Al ₂ O ₃ is formed on a porous silica substrate having a porosity of 35% to 70% and an average pore diameter of 250 nm to 450 nm.

In order to achieve the above object, a method for producing a fluid separation material of the present invention comprises:
After dip-coating a high silica zeolite seed crystal on a porous silica substrate having a porosity of 35% or more and 70% or less and an average pore diameter of 250 nm or more and 450 nm or less at a pH of 4 or less, the seed crystal is formed by a hydrothermal synthesis method. Secondary growth is performed to form a high silica zeolite membrane.

  According to the present invention, it is possible to provide a porous silica substrate for a high silica zeolite membrane provided with a high silica zeolite membrane that is easy to produce and improved in yield, and a fluid separation material using the substrate.

It is a longitudinal cross-sectional view which shows the example of the fluid separation material which is one Embodiment of this invention. It is a schematic diagram which shows one Embodiment of the manufacturing method of this invention. It is sectional drawing which shows the example of the porous silica base | substrate provided with the gas seal part. It is a figure which shows the fluid separation module provided with the fluid separation material which concerns on this invention. It is an electron micrograph of the high silica zeolite membrane formed on the surface of the fluid separation material of FIG. It is a schematic diagram which shows an example of the apparatus which measures a transmission coefficient. It is a schematic diagram which shows the other example of the apparatus which measures a transmission coefficient. It is a schematic diagram which shows the other example of the apparatus which measures a transmission coefficient.

[Description of Embodiment of Present Invention]
First, the contents of the embodiments of the present invention will be listed and described.
A porous silica substrate for a high silica zeolite membrane according to an embodiment of the present invention,
(1) The porosity is 35% to 70%, and the average pore diameter is 250 nm to 450 nm.
ADVANTAGE OF THE INVENTION According to this invention, the porous silica base | substrate for high silica zeolite membranes which has high gas permeability, does not contain an alumina as a structural component, and has a small thermal expansion difference with a high silica zeolite membrane can be provided.

The fluid separation material according to the embodiment of the present invention is:
(2) A high silica zeolite membrane having a SiO ₂ / Al ₂ O ₃ molar ratio of 30 or more is formed on the porous silica substrate for a high silica zeolite membrane described in (1) above.
By using a porous silica substrate, a high silica zeolite membrane having a molar ratio in the above range can be formed with high yield.

The fluid separation material according to the embodiment of the present invention is:
(3) A high silica zeolite membrane not containing Al ₂ O ₃ is formed on the porous silica substrate for a high silica zeolite membrane described in (1) above.
By using a porous silica substrate, a high silica zeolite membrane containing no Al ₂ O ₃ can be easily formed.

The fluid separation material according to the embodiment of the present invention is
(4) The structural type of the high silica zeolite membrane is preferably MFI type.
This is because the pore size is suitable for the separation of lower hydrocarbons which are important intermediates in the petrochemical industry.

A method for producing a fluid separation material according to an embodiment of the present invention is as follows.
(5) After dip-coating the high silica zeolite seed crystal on the porous silica substrate for high silica zeolite membrane described in (1) above at a pH of 4 or less, the seed crystal is secondarily grown by a hydrothermal synthesis method. A high silica zeolite membrane is formed.
By applying high-silica zeolite seed crystals at a high density on the surface of the porous silica substrate, a fluid separation material having a low defect density and a high separation performance can be produced.

[Details of the embodiment of the present invention]
Hereinafter, examples of embodiments of a porous silica substrate for a high silica zeolite membrane, a fluid separation material, and a method for producing the same according to the present invention will be described with reference to the drawings.
In this embodiment, a fluid separation material in which an MFI type high silica zeolite membrane is formed on a porous silica substrate will be described as an example. The shape of the fluid separation material can be an arbitrary shape such as a planar shape, but in order to increase the contact area with the fluid from the viewpoint of reaction efficiency, it is tubular in this embodiment.

(Fluid separation material)
FIG. 1 illustrates one embodiment of a fluid separation material. FIG. 1 is a longitudinal sectional view of a fluid separation material.
The fluid separation material 20 has a substantially cylindrical shape, and has a central hole 24 having a substantially circular cross section extending in the longitudinal direction at the center thereof. The fluid separation material 20 has a porous silica substrate 21 for a high silica zeolite membrane as a tube wall on the outer periphery of the center hole 24. A high silica zeolite membrane 22 is formed on the outer periphery of the porous silica substrate 21.

Since the porous silica substrate 21 supports the thin film without substantially interfering with the permeation of fluid through the high silica zeolite membrane 22, the porosity of the porous silica substrate 21 is 35 to 70% and the average pore diameter is 250 nm to 450 nm. It is said. The “porosity” can be calculated as the ratio of the air volume per unit volume.
Furthermore, the thickness of the porous silica substrate 21 is not particularly limited, but is preferably 0.2 mm to 5 mm, and preferably 0.5 mm to 3 mm in view of the balance between mechanical strength and gas permeability. Is more preferable.

The high silica zeolite membrane 22 formed on the outer periphery of the porous silica substrate 21 of the present embodiment means a high silica zeolite membrane having a SiO ₂ / Al ₂ O ₃ molar ratio of 30 or more, and Al ₂ O ₃ High silica zeolite membranes that do not contain any are also included. When the SiO ₂ / Al ₂ O ₃ molar ratio is less than 30, the difference in thermal expansion between the porous silica substrate 21 and the high silica zeolite membrane 22 becomes large, and cracks are likely to occur in the high silica zeolite membrane 22 during high temperature treatment.

  The thickness of the high silica zeolite membrane 22 is not particularly limited, but is preferably 0.5 μm to 30 μm. If the thickness is less than 0.5 μm, pinholes are likely to occur in the high silica zeolite membrane 22 and sufficient separation performance cannot be obtained. If the thickness exceeds 30 μm, the fluid permeation rate becomes too low. In some cases, practically sufficient separation performance may be difficult to obtain.

Hereinafter, an embodiment of a method for producing the fluid separation material 20 will be described with reference to FIGS. 1 and 2.
First, porous silica substrate 21 is produced by depositing silica glass particles around rod 30 (see FIG. 2A). The rod 30 is arranged vertically so that the tip portion is on the bottom. Moreover, it is good also as a form which arrange | positions the rod 30 horizontally. As a material of the rod 30, glass, fireproof ceramics, or the like can be used. After the rod 30 is fixed, the rod 30 is rotated about the central axis. Then, silica glass particles are deposited on the outer periphery of the rod 30 by a burner 31 disposed on the side of the rod 30 by a sooting method (CVD method). By changing the generation rate of the silica glass particles, the moving speed of the burner 31, the deposition temperature, and the like, a porous silica material having a desired porosity, pore diameter, and thickness can be deposited. By pulling out the rod 30 from the deposited porous silica, a cylindrical porous silica substrate 21 is produced (see FIG. 2B). It is also possible to produce a tubular porous silica substrate 21a having a closed tip by using a rod 30a having a round tip and depositing silica glass particles on the tip of the rod 30a (see FIG. 2 (c)).
In addition, the porous silica glass which comprises the porous silica base | substrate 21 can be manufactured by manufacturing methods, such as an injection molding method other than a sooting method (CVD method).

  The porous silica substrate 21 is partially heated to be densified, or welded to a commercially available transparent quartz tube, thereby forming a substrate 26 having the gas seal portion 25 shown in FIG. You can also. Further, as shown in FIG. 3B, a tubular base body 26a having a closed tip can be produced. With such a structure, the fluid separation module 40 shown in FIG. 4 can be produced without applying mechanical stress to the high silica zeolite membrane 22 to be formed later. By installing the base body 26a in the fluid separation module 40, only the desired permeated fluid is taken out from the supply fluid supplied into the fluid separation module 40 by the base body 26a, and for the non-permeated fluid other than the permeated fluid, the fluid separation module. 40 can be appropriately discharged.

  Next, a high silica zeolite membrane 22 is formed on the surface of the porous silica substrate 21 (see FIG. 1). In this example, the high silica zeolite membrane 22 includes a seed crystal coating step in which a seed crystal of high silica zeolite is applied to the surface of the porous silica substrate 21, and the surface of the porous silica substrate 21 by growing the zeolite seed crystal. A zeolite membrane forming step for forming the high silica zeolite membrane 22 and a structure directing agent removing step for removing the structure directing agent by heat-treating the high silica zeolite crystals.

(Seed crystal application process)
The seed crystal of high silica zeolite used for the production of the high silica zeolite membrane 22 of the present invention can be synthesized according to a conventionally known method. First, a silica sol, a structure directing agent, water, and other necessary additive components are mixed at a predetermined concentration to prepare a seed crystal generation sol, and the seed crystal generation sol is hydrothermally treated using a pressure vessel. The sol for seed crystal formation forms a zeolite crystal having a structure derived from the structure directing agent by hydrothermal treatment.

  As the silica sol, it is preferable to use a commercially available silica sol or one prepared by hydrolyzing an alkoxysilane. As water, distilled water or ion-exchanged water having a low impurity ion concentration is preferably used. The seed crystal generation sol preferably has a molar ratio of water to silica (water / silica) of 10 to 50. When the water / silica molar ratio is less than 10, the homogeneity of the silica sol may be lowered, and when it is more than 50, the seed crystal generation efficiency may be lowered.

  Since the structure-directing agent varies depending on the type of zeolite crystal, a structure-directing agent corresponding to the desired crystal-type zeolite is appropriately selected and used. As a structure-directing agent for MFI-type zeolite, tetrapropylammonium hydroxide (TPAOH) or tetrapropylammonium bromide (TPABr) that generates tetrapropylammonium ions (TPA) is used. The molar ratio of TPA to silica (TPA / silica ratio) is preferably in the range of 0.1 to 0.5. If the TPA / silica ratio is less than 0.1, zeolite crystals may not precipitate, and if it exceeds 0.5, the homogeneity of the zeolite crystals may be reduced.

  Although it does not specifically limit to hydrothermal synthesis, The commercially available stainless steel pressure-resistant container with a fluororesin inner cylinder can be used. The temperature for hydrothermal synthesis is preferably 90 to 130 ° C. If it is lower than 90 ° C., hydrothermal synthesis is difficult to proceed, and if it is higher than 130 ° C., the size of the obtained zeolite crystal may be too large. The hydrothermal synthesis time is preferably 5 to 30 hours. If it is shorter than 5 hours, hydrothermal synthesis may not proceed sufficiently, and if it is longer than 30 hours, the zeolite crystals may become too large.

  The synthesized high silica zeolite crystal is preferably washed using hot water or the like in order to suppress the subsequent crystal growth. Moreover, after washing | cleaning, it is preferable to make it dry at 60-120 degreeC for 5-48 hours.

  The high-silica zeolite seed crystal can be applied by immersing the porous silica substrate 21 adjusted to an appropriate length in a seed crystal dispersion in which the seed crystal is dispersed in water, then pulling it up and drying it. .

  The particle diameter of the high silica zeolite seed crystal is preferably 0.2 to 3 μm. If necessary, the high silica zeolite crystal obtained by the hydrothermal synthesis can be used after being pulverized and classified. If the seed crystal particle diameter is larger than 3 μm, the finally obtained high silica zeolite membrane 22 becomes too thick and the defect concentration also increases, so that it is difficult to obtain the fluid separation material 20 having sufficient separation performance. There is a case. If it is smaller than 0.2 μm, the seed crystal penetrates deeply into the porous silica substrate 21 when dip-coated, so that the thickness of the finally obtained high silica zeolite membrane 22 is effectively increased and sufficient separation is achieved. It may be difficult to obtain the fluid separation material 20 having performance.

  In order to improve the separation performance of the finally obtained high silica zeolite membrane 22, it is preferable to increase the density of the seed crystals applied to the surface of the porous silica substrate 21. For this reason, the dispersion concentration of the zeolite seed crystal and the dipping time and pulling speed of the porous silica substrate 21 can be appropriately adjusted according to the particle diameter of the seed crystal and the shape of the porous silica substrate 21.

  The dispersion is preferably adjusted to pH 4 or less at which the zeta potential of the porous silica substrate 21 is close to 0 by adding hydrochloric acid or the like (see Non-Patent Document 1). FIG. 5 (a) is an electron micrograph of the high silica zeolite membrane 22 when a seed crystal of high silica zeolite is dip-coated on the surface of the porous silica substrate 21 at pH 2. FIG. 3 is an electron micrograph of a high silica zeolite membrane 22 when a zeolite seed crystal is dip-coated on the surface of a porous silica substrate 21 at pH 7. FIG. As can be seen from the electron micrographs shown in FIGS. 5 (a) and 5 (b), the electrical generated between the surface of the high silica zeolite seed crystal and the surface of the porous silica substrate 21 when the pH is in the range of pH 4 or less. The repulsive force can be reduced, and the high silica zeolite seed crystal can be applied to the surface of the porous silica substrate 21 at a high concentration.

  The state where the zeolite seed crystals are attached to the surface of the porous silica substrate 21 can be observed with a scanning electron microscope, and the ratio of the zeolite seed crystals covering the surface of the porous silica substrate 21 is 50% or more. It is preferable.

(Zeolite membrane formation process)
A porous silica substrate 21 coated with a high silica zeolite seed crystal is immersed in a film-forming sol and hydrothermally synthesized using a pressure vessel to form a high silica zeolite membrane 22 on the surface of the porous silica substrate 21.

  The film-forming sol uses the silica sol, structure directing agent, water, and other optional components contained in the above-mentioned seed crystal generation sol, and has a higher water concentration than the seed crystal generation sol. It is preferable to do. The water / silica molar ratio of the film-forming sol is preferably 100 to 900. When the water / silica molar ratio is less than 100, high silica zeolite crystals are deposited in the film-forming sol and are deposited on the surface of the film, making it difficult to obtain the high silica zeolite film 22 having a low defect density. If the water / silica molar ratio is greater than 900, the growth rate of the seed crystal may be too small.

  The TPA / silica molar ratio is preferably mixed so that the TPA / silica molar ratio is in the range of 0.1 to 0.5, similar to the seed crystal-forming sol. When the TPA / silica molar ratio is less than 0.1, a dense high silica zeolite membrane 22 is difficult to obtain, and when it exceeds 0.5, zeolite crystals may be deposited on the membrane surface.

  As the pressure vessel, a commercially available stainless steel pressure vessel with a fluororesin inner cylinder used in the zeolite seed crystal coating step can be used. The hydrothermal synthesis temperature is preferably 100 to 200 ° C. When the synthesis temperature is lower than 100 ° C., the high silica zeolite seed crystal does not grow sufficiently. When the synthesis temperature is higher than 200 ° C., the defect density may increase. The hydrothermal synthesis time is preferably 5 to 72 hours. If it is shorter than 5 hours, the high silica zeolite seed crystal may not grow sufficiently, and if it is longer than 72 hours, the high silica zeolite membrane 22 may become too thick.

  The high silica zeolite crystal formed on the porous silica substrate 21 is preferably washed using hot water or the like in order to suppress the subsequent crystal growth. Moreover, after washing | cleaning, it is preferable to make it dry at 60-120 degreeC for 5-48 hours.

(Structure directing agent removal process)
Since the high silica zeolite membrane 22 formed on the surface of the porous silica substrate 21 by hydrothermal synthesis in the zeolite membrane forming step contains a structural regulating agent, the structural regulating agent is burned by heat treatment, and the high silica zeolite membrane 22 is burned. Remove from. The heating temperature is preferably 400 to 600 ° C., and the heating time is preferably 2 to 48 hours. Moreover, it is preferable that the temperature increase / decrease rate is 1 ° C./min or less.

  As described above, in the present embodiment, the porous silica substrate 21 for the high silica zeolite membrane 22 is a porous silica substrate having a porosity of 35% to 70% and an average pore diameter of 250 nm to 450 nm. 21 is used. Therefore, it has high permeability, and since the difference in thermal expansion from the high silica zeolite membrane 22 is small, the generation of cracks when sintering the high silica zeolite membrane 22 can be suppressed, and the yield can be improved.

Further, according to the present embodiment, since the porous silica substrate 21 is composed of silica particles, the problem of alumina elution from the porous silica substrate 21 to the high silica zeolite membrane 22 can be solved. Therefore, the SiO ₂ / Al ₂ O ₃ molar ratio of the high silica zeolite membrane 22 can be easily controlled.
Similarly, a high silica zeolite membrane not containing Al ₂ O ₃ can be formed as the high silica zeolite membrane 22.

  In addition, according to the present embodiment, the high silica zeolite seed crystal is dip-coated on the porous silica substrate 21 at a pH of 4 or less, and then the high silica zeolite seed crystal is secondarily grown by a hydrothermal synthesis method. A film 22 is formed. Thereby, the fluid separation material 20 in which the high silica zeolite membrane 22 having a low defect density is formed on the surface of the porous silica substrate 21 can be manufactured.

Example 1
(Preparation of porous silica substrate)
A porous silica tube having an outer diameter of 10 mm, an inner diameter of 6 mm, a length of 300 mm, a porosity of 64%, and an average pore diameter of 400 nm was prepared by an external CVD method, and the tube cut into a length of 30 mm was used as a porous for high silica zeolite. Used as a porous silica substrate.
(Preparation of high silica zeolite seed crystals)
Colloidal silica, TPABr, sodium hydroxide and distilled water are used as raw materials and mixed so that the molar ratio of SiO ₂ : TPABr: Na ₂ O: H ₂ O is 1: 0.25: 0.15: 40, A sol for seed crystal generation was obtained by stirring at room temperature for 60 minutes. This sol was reacted in a pressure vessel at 130 ° C. for 20 hours to synthesize MFI-type zeolite crystals (Silicalite-1). The zeolite crystals were collected by suction filtration, washed with hot water, and then dried at 100 ° C. for 24 hours. The fired crystals were pulverized in an automatic mortar for 6 hours to obtain high silica zeolite seed crystals having a particle size of about 3 μm.
(Application of high silica zeolite seed crystal)
The seed crystal was dispersed in pure water at a concentration of 8 g / L, and the pH of this dispersion was adjusted to 2 by adding HCl. After immersing the porous silica substrate in this seed crystal dispersion for 30 seconds, the porous silica substrate was pulled up from the dispersion and coated with a high silica zeolite seed crystal on the surface of the porous silica substrate. The substrate coated with the seed crystal was dried at 100 ° C. for 24 hours.
(Formation of high silica zeolite membrane)
Using tetramethoxysilane, TPABr, sodium hydroxide and distilled water as raw materials, mixing so that the molar ratio of SiO ₂ : TPABr: Na ₂ O: H ₂ O is 1: 0.3: 0.05: 600, The film-forming sol was obtained by stirring at 40 ° C. for 60 minutes. A porous silica substrate coated with a zeolite seed crystal is immersed in this film-forming sol and allowed to react at 180 ° C. for 16 hours in a pressure-resistant container to form an MFI-type zeolite (Silicalite-1) on the surface of the porous silica substrate. did. In order to remove TPABr, which is a structure-directing agent, from this film, baking was performed in air at 500 ° C. for 15 hours. During the firing, the temperature raising / lowering rate was 0.5 ° C./min. With respect to the fluid separation material according to Example 1 (Example 1) manufactured as described above, the transmission coefficient at room temperature of N ₂ , SF ₆ , C ₃ H ₆ , and C ₃ H ₈ was measured. The results are shown in Table 1.

(Example 2)
A porous silica tube having an outer diameter of 10 mm, an inner diameter of 6 mm, a length of 300 mm, a porosity of 39%, and an average pore diameter of 250 nm was prepared by an external CVD method, and the tube cut into a length of 30 mm was made into a porous for high silica zeolite. Used as a porous silica substrate. A high silica zeolite membrane was prepared in the same manner as in Example 1 except that this porous silica substrate was used.
With respect to the fluid separation material according to Example 2 (Example 2) manufactured in this way, the permeability coefficient of zeolite membrane N ₂ and SF ₆ at room temperature was measured. The results are shown in Table 1.

(Examples 3 and 4)
A high silica zeolite membrane was prepared in the same manner as in Example 1, except that the pH of the high silica zeolite seed crystal dispersion was adjusted to 7 (Example 3) or 12 (Example 4).
With respect to the fluid separation materials according to Examples 3 and 4 (Examples 3 and 4) produced in this manner, the permeability coefficient of N ₂ and SF ₆ of the zeolite membrane at room temperature was measured. The results are shown in Table 1.

In Examples 1 to 4, the transmission coefficients of N ₂ , SF ₆ , C ₃ H ₆ , and C ₃ H ₈ were measured using an apparatus schematically shown in FIG. 6 in an environment at room temperature (25 ° C.). went.
As shown in FIG. 6, a single component measurement gas containing any of N ₂ , SF ₆ , C ₃ H ₆ , and C ₃ H ₈ is supplied into the fluid separation material 20. A stop valve 41 is provided in the pipeline of gas (non-permeated gas) exhausted through the central hole of the fluid separation material 20. The supply amount of the single component measurement gas is adjusted so that the internal pressure of the fluid separation material 20 is 0.2 MPa. Due to the pressure difference between the inside and outside of the fluid separation material 20, a part of the gas supplied into the fluid separation material 20 passes through the fluid separation material 20. This permeated gas is sent to the soap film flow meter 42 and the flow rate is measured.

The fluid separation material according to Example 1 exhibited separation performance of N ₂ / SF ₆ = 110 and C ₃ H ₆ / C ₃ H ₈ = 6.2 in terms of the permeability coefficient ratio. In addition, the fluid separation material according to Example 2 exhibited a separation performance of N ₂ / SF ₆ = 85 in terms of a permeability coefficient ratio.
According to the observation of the zeolite membrane with a field emission electron microscope, the thickness of the zeolite membrane of Example 1 and Example 2 was about 10 μm, and it was confirmed that no crack was formed. Further, it was confirmed by an electron beam microanalyzer that the zeolite membrane did not contain Al.
From the above results, the use of a porous silica substrate having a porosity of 35% or more and 70% or less and an average pore diameter of 250 nm or more and 450 nm or less suppresses the generation of cracks and alumina elution from the substrate. It was confirmed that can be formed.

The fluid separation material according to Example 3 exhibited a separation performance of N ₂ / SF ₆ = 36 in terms of permeability coefficient ratio. In addition, the fluid separation material according to Example 4 exhibited a separation performance of N ₂ / SF ₆ = 29 in terms of a permeability coefficient ratio.
According to the observation of the zeolite membrane by a field emission electron microscope, the thickness of the zeolite membrane of Example 3 and Example 4 was about 10 μm, and it was confirmed that no crack was formed. Further, it was confirmed by an electron beam microanalyzer that the zeolite membrane did not contain Al.
From the comparison with Example 1, it was confirmed that in order to improve the separation characteristics of the high silica zeolite membrane, it was necessary to adjust the dispersion of the high silica zeolite seed crystal to pH 4 or lower in the seed crystal coating step. .

Further, using the fluid separation material according to Example 1, the permeation coefficients of o-xylene and p-xylene were measured. Since both o- / p-xylene are liquid at room temperature, they were vaporized by heating with the apparatus shown in FIG.
As shown in FIG. 7, using a bubbler 45 with a heater containing liquid xylene, xylene is heated to 75 ° C., vaporized, and supplied into the fluid separation material 20. Note that xylene in the bubbler 45 with heater is composed of a single component of either o-xylene or p-xylene.
The fluid separation material 20 is kept at 100 ° C. by the heater 47. A sweep gas (N ₂ ) is supplied to the outside of the fluid separation material 20. The gas (non-permeate gas) passing through the center hole of the fluid separation material 20 is exhausted as it is. Both the inside and outside of the fluid separation material 20 are at atmospheric pressure. A part of the xylene gas supplied into the fluid separation material 20 permeates the fluid separation material 20 due to a partial pressure difference. This permeate gas is sent to gas chromatography 46 where its components and flow rates are measured.
As a result of such measurement, the permeability coefficient (mol · m ⁻² · s ⁻¹ · Pa ⁻¹ ) was p-xylene: 1.06 × 10 ⁻⁷ , o-xylene: 1.09 × 10 ⁻⁸ , The separation performance was p-xylene / o-xylene = 9.8 in terms of permeability coefficient ratio.

Further, by using the fluid separation material according to Example 1, the measuring apparatus shown in FIG. _8, was measured transmission coefficients of _{n-C 4 H 10, i} -C 4 H 10.
As shown in FIG. 8, a mixed gas in which n-C ₄ H ₁₀ and i-C ₄ H ₁₀ are mixed at a molar ratio of 1: 1 is supplied into the fluid separation material 20. The fluid separation material 20 is kept at 150 ° C. by the heater 47. A sweep gas (N ₂ ) is supplied to the outside of the fluid separation material 20. The gas (non-permeate gas) passing through the center hole of the fluid separation material 20 is exhausted as it is. Both the inside and outside of the fluid separation material 20 are at atmospheric pressure. A part of the mixed gas of n-C ₄ H ₁₀ and i-C ₄ H ₁₀ supplied into the fluid separation material 20 permeates the fluid separation material 20 due to a partial pressure difference. This permeate gas is sent to gas chromatography 46 where its components and flow rates are measured.
As a result of such a measurement, the transmission coefficient (mol · m ⁻² · s ⁻¹ · Pa ⁻¹ ) is nC ₄ H ₁₀ : 3.15 × 10 ⁻⁷ , iC ₄ H ₁₀ : 2. 91 × ^{10 -8,} is exhibited separation performance of _{n-C 4 H 10 / i} -C 4 H 10 = 10.8 in permeability coefficient ratio.

(Comparative Example 1)
A commercially available porous alumina tube was cut to prepare a porous alumina substrate having an outer diameter of 10 mm, an inner diameter of 7 mm, a length of 30 mm, a porosity of 40%, and an average pore diameter of 700 nm. A high silica zeolite membrane was produced in the same manner as in Example 4 except that this substrate was used.

  When the cross section of the zeolite membrane of Comparative Example 1 was observed with a field emission electron microscope, the thickness was about 10 μm, and it was confirmed that cracks were formed. Further, it was confirmed by an electron beam microanalyzer that the zeolite film contained Al, and the concentration was higher as the distance from the substrate surface was closer, and it was confirmed that the zeolite film reached at least 4000 ppm.

  While the invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention. In addition, the number, position, shape, and the like of the constituent members described above are not limited to the above-described embodiments, and can be changed to a number, position, shape, and the like that are suitable for carrying out the present invention.

20: Fluid separation material 21: Porous silica substrate 22: High silica zeolite membrane 24: Center hole 25: Gas seal part 26: Substrate 30: Rod 31: Burner 40: Fluid separation module 41: Stop valve 42: Soap membrane flow meter 45: Bubbler 46: Gas chromatography 47: Heater

Claims (5)

  A porous silica substrate for a high silica zeolite membrane having a porosity of 35% to 70% and an average pore diameter of 250 nm to 450 nm. A fluid separation material, wherein a high silica zeolite membrane having a SiO ₂ / Al ₂ O ₃ molar ratio of 30 or more is formed on the porous silica substrate for a high silica zeolite membrane according to claim 1. A fluid separation material, wherein a high silica zeolite membrane not containing Al ₂ O ₃ is formed on the porous silica substrate for a high silica zeolite membrane according to claim 1.   The fluid separation material according to claim 2 or 3, wherein a structural type of the high silica zeolite membrane is MFI type.   After immersing the porous silica substrate for high silica zeolite membrane according to claim 1 in a zeolite seed crystal dispersion liquid adjusted to pH 4 or lower, and then lifting the substrate from the dispersion liquid and applying seed crystals to the substrate surface, A method for producing a fluid separation material, wherein a high-silica zeolite membrane is formed by secondary growth of seed crystals applied to a substrate surface by a hydrothermal synthesis method.