JP2016068084A - Hydrogen separator and hydrogen separation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydrogen separator using a molecular sieve membrane and capable of separating hydrogen efficiently and preventing an explosion, and a hydrogen separation method.SOLUTION: A hydrogen separator includes a molecular sieve membrane for separating hydrogen from mixed gas, and a slit material that has a plurality of slits and is disposed in a space defined by the molecular sieve membrane or is disposed so as to cover the outside of the molecular sieve membrane. The slit material comprises an aggregate of filler.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a hydrogen separation apparatus and a hydrogen separation method using a molecular sieve membrane that can efficiently separate hydrogen and prevent explosion.

  In recent years, a technique for decomposing water and producing hydrogen or oxygen using a photocatalyst and solar energy has attracted attention. In the photohydrolysis reaction using a photocatalyst, hydrogen and oxygen may be generated in the system at the same time. In this case, it is necessary to separate the generated hydrogen and oxygen. For example, in a hydrogen production process by water splitting of a photocatalyst, techniques for separating hydrogen and oxygen using a separation membrane such as a molecular sieve membrane have been proposed (Non-Patent Documents 1 and 2).

Tanaka et al., “Application of Hydrogen Separation Membrane to Photocatalytic Hydrogen Production Process”, Membrane Symposium No. 21 (2009) Sugiyama et al., "Efficient separation of H2 and O2 produced by photocatalytic water complete decomposition using a gas separation membrane", 104th Catalytic Conference, Proceedings of Conference A, p. 20, (2009)

  As disclosed in Non-Patent Documents 1 and 2, when a photocatalytic reactor and a separation membrane module are combined, there is a problem that an explosion easily occurs due to a reaction between hydrogen and oxygen in the separation membrane module. This problem can be dealt with by, for example, reducing the hydrogen concentration and oxygen concentration in the separation membrane module using an inert diluent gas such as nitrogen. However, when a dilution gas is used, in order to obtain high concentrations of hydrogen and oxygen, a separation process between the dilution gas and hydrogen and / or oxygen is further required, which complicates the process. Moreover, since the hydrogen concentration and the oxygen concentration are lowered by the dilution gas, when it is desired to separate and recover a large amount of hydrogen and oxygen, the separation efficiency is deteriorated.

  Accordingly, the present invention provides a hydrogen separation apparatus and a hydrogen separation method using a molecular sieve membrane that can efficiently separate hydrogen from a mixed gas containing hydrogen and that can prevent explosion due to the reaction of the mixed gas. This is the issue.

  The inventors of the present invention have made it possible to cause an explosion due to a reaction of a mixed gas by circulating a mixed gas containing hydrogen through a narrow gap (narrow channel) having a small gap diameter in a gap material made of an aggregate of fillers. It was found that hydrogen can be selectively separated from the mixed gas by connecting the slit and the molecular sieve membrane while preventing generation.

The present invention has been completed based on the above findings. That is,
A first aspect of the present invention is a molecular sieve membrane for separating hydrogen from a mixed gas, and a plurality of fine membranes arranged in a space defined by the molecular sieve membrane or arranged outside the molecular sieve membrane. And a slit member having a gap, wherein the slit member is made of an aggregate of fillers.

  In the present invention, the “mixed gas” refers to a gas including at least “hydrogen” and “a gas that can explode when reacted with hydrogen”. “Oxygen” is an example of a gas that can explode when reacted with hydrogen. The mixed gas may contain an inert gas such as nitrogen, water vapor, or the like in addition to hydrogen and a gas that may explode upon reaction with hydrogen.

  The “slit” refers to a narrow channel through which a mixed gas containing hydrogen can flow.

  “Slit material having a plurality of slits” means that by having a plurality of slits, gas can be circulated and permeated in a direction from one to the other and in a direction intersecting with the direction. A possible member.

  “The slit material disposed in the space defined by the molecular sieve membrane” means at least a surface (one end surface) corresponding to the gas inlet of the slit material and a surface (other end surface) corresponding to the gas outlet. It means that the removed outer surface (side surface) is covered with a molecular sieve membrane, and the case where a part or all of one end surface and the other end surface are covered with a molecular sieve membrane is also included. In addition to a form in which the molecular sieve membrane is in direct contact with the surface of the slit material, a form in which the molecular sieve membrane covers the surface of the slit material through some member is also included. For example, a form in which a space inside a cylindrical molecular sieve membrane is filled with a filler to form a slit material is also included.

  The term “slit material that covers the outside of the molecular sieve membrane” means that the molecular sieve membrane is provided inside the slit material, and the molecular sieve membrane is in direct contact with the surface of the slit material. In addition, a mode in which the molecular sieve membrane covers the surface of the slit material via some member is also included. For example, a form in which the space outside the cylindrical molecular sieve membrane is filled with a filler to form a slit material is also included.

  “Filler” is a material that allows a gas to flow and permeate in the direction from one side to the other and in the direction intersecting with the direction when it forms an aggregate. I just need it. That is, it may be solid, and may be any of inorganic fillers, organic fillers, or combinations thereof.

  In the first aspect of the present invention, it is preferable that the longest gap diameter of the narrow gap is not more than a predetermined length. For example, the longest gap diameter of the narrow gap is preferably 1700 μm or less, more preferably 600 μm or less, particularly preferably 450 μm or less, and most preferably 310 μm or less.

  The “gap diameter” means the diameter of a slit existing in the slit material. In the present invention, the diameter of the slit is defined as follows.

  FIG. 1 shows a cross-sectional view around a slit when the slit material is an aggregate of spherical fillers.

  As shown in FIG. 1, in the present invention, a sphere inscribed in a three-dimensional slit is assumed, and the diameter is defined as a “gap diameter”. (A) in FIG. 1 corresponds to the diameter of the sphere inscribed in the slit, that is, the gap diameter, but in FIG. 1 (b), the sphere having this diameter is not inscribed in the slit. Not applicable.

  The “gap diameter” can be measured as the size of the gap by photographing a sample with an X-ray CT apparatus and analyzing the obtained X-ray CT data. Therefore, the longest gap diameter can be measured as the maximum value of the size of the gap.

  If the X-ray CT analysis cannot distinguish between the sample tube, filler, and slit due to the influence of the material, such as the filler in the metal tube, measure the structure of the same shape of the measurable material. It is possible to analyze the structure of the slit. For example, a slit can be analyzed by using, as an analysis sample, an acrylic tube having the same shape as a sample tube and filled with a filler capable of distinguishing between the filler and the slit. The filling state can be a sample in which the state of the slit can be reproduced by making the shape of the sample tube and the filler the same, and by matching the filling rate.

  In the first aspect of the present invention, an inorganic porous substrate is preferably further provided between the slit material and the molecular sieve membrane.

  In the first aspect of the present invention, when an inorganic porous substrate is further provided, the inorganic porous substrate is preferably alumina.

  In the first aspect of the present invention, the average particle diameter of the filler used for the filler aggregate is preferably 80 μm or more and 1700 μm or less.

  The “average particle diameter” can be measured as a median diameter on a volume basis by a laser diffraction / scattering particle size distribution measuring apparatus.

  In the first aspect of the present invention, the molecular sieve membrane is preferably any one of a zeolite membrane, a silica membrane, and a carbon membrane, or a combination thereof.

  In the first aspect of the present invention, when a zeolite membrane is used as the molecular sieve membrane, the crystalline zeolite skeleton forming the pores of the zeolite membrane is preferably an oxygen 8-membered ring or less.

  In the first aspect of the present invention, when a zeolite membrane is used as the molecular sieve membrane, the zeolite membrane preferably contains CHA-type zeolite.

  The second aspect of the present invention is a first step of supplying a mixed gas to the slit material of the hydrogen separator according to the first aspect of the present invention, and a second step of separating hydrogen from the mixed gas supplied in the first step. A hydrogen separation method comprising the steps of:

  Explosion can be avoided by using the slit material in a portion where a mixed gas containing hydrogen having a composition within the explosion range exists or a portion where the gas composition can enter the explosion range for any reason. .

  In addition, a part of the apparatus that is desired to avoid explosion may be used in combination with a member having a flame extinguishing function such as a flame arrester (a safety device that prevents a large fire from spreading or an explosion when a fire occurs).

  According to the hydrogen separation device and the hydrogen separation method of the present invention, hydrogen can be efficiently separated from a mixed gas containing hydrogen by using a molecular sieve membrane and a slit material made of an aggregate of fillers. In addition, it is possible to prevent an explosion due to the reaction of the mixed gas.

It is a figure for demonstrating the definition of the clearance gap diameter of the slit formed of the slit material in this invention. It is a figure for demonstrating the hydrogen separation apparatus which concerns on this invention. It is a figure for demonstrating an example of the slit (gas flow path) formed in the slit material. It is FIG. (1) for demonstrating the hydrogen separator (hydrogen separator 50a) with which a hydrogen separator is equipped. It is FIG. (2) for demonstrating the hydrogen separator (hydrogen separator 50a) with which a hydrogen separator is equipped. It is a figure for demonstrating the hydrogen separator (hydrogen separator 50b) which concerns on other embodiment. It is a figure (the 1) for demonstrating the hydrogen separator (hydrogen separator 50c) which concerns on other embodiment. It is FIG. (2) for demonstrating the hydrogen separator (hydrogen separator 50c) which concerns on other embodiment. It is a figure for demonstrating the hydrogen separator (hydrogen separator 50d) which concerns on other embodiment. It is a figure for demonstrating the definition of the continuous length of a slit. It is a figure for demonstrating a flame-extinguishing test apparatus.

  When a mixed gas containing hydrogen is circulated, the ease of explosion changes depending on the diameter of the flow path. For example, it is known that the flame extinguishing diameters of the mixed gas containing hydrogen and oxygen and the mixed gas containing hydrogen and air (the inner diameter of the tube where the flame does not propagate through the pipe) are 310 μm and 860 μm, respectively ( Explosion Prevention Practical Handbook, p221 (1983)).

  In the case where a mixed gas is circulated in a slit material composed of an aggregate of fillers, the present inventors include a slit having a gap diameter longer than the above-mentioned extinguishing diameter in the slit material. Even so, it was found that explosion can be prevented. It was also found that hydrogen can be selectively separated from the slit material through a molecular sieve membrane. In addition, various forms of the combination of the slit material and the molecular sieve membrane were invented. Hereinafter, a hydrogen separation method and a hydrogen separation apparatus according to the present invention will be described.

1. Hydrogen Separation Method In the hydrogen separation method according to the present invention, a molecular sieve membrane that separates hydrogen from a mixed gas containing hydrogen and a space separated by the molecular sieve membrane, or the outer side of the molecular sieve membrane is covered. And a slit material having a plurality of slits, wherein the slit material separates hydrogen from the mixed gas by using a hydrogen separator composed of an aggregate of fillers. Specifically, the method includes a first step of supplying a mixed gas to the slit material of the hydrogen separator, and a second step of separating hydrogen from the mixed gas supplied in the first step. And

  In the hydrogen separation method according to the present invention, hydrogen is introduced into one space provided with a slit material having a plurality of slits among one space and the other space sandwiching the molecular sieve membrane partitioned by the molecular sieve membrane. While supplying the mixed gas containing hydrogen, the hydrogen in the mixed gas is selectively permeated to the other space sandwiching the molecular sieve membrane by using the partial pressure difference of hydrogen as a driving force. Here, “one space” and “the other space” mean spaces on one side and the other side partitioned by a molecular sieve membrane. For example, when the inner space closed by the molecular sieve membrane is “one space” when the molecular sieve membrane is a closed system such as a cylinder, the outer space of the molecular sieve membrane corresponds to the “other space” . The “partial pressure difference” refers to a gas pressure difference between “one space” and “the other space”.

  The difference in hydrogen partial pressure as the driving force is, for example, a method of pressurizing a gas in one space (space A), setting the other space (space B) to atmospheric pressure or reduced pressure, and flowing a sweep gas, A method in which the gas in the space (space A) is set to normal pressure and the other space (space B) is depressurized or a sweep gas is flowed, or a combination thereof, pressurization of the space A and slight pressurization of the space B It can be set by combining. For example, when a sweep gas is allowed to flow in the space B, the hydrogen concentration in the space B can be reduced, so that even if the gas pressure in the space A is a normal pressure, a hydrogen partial pressure difference can be ensured.

  The pressure in the hydrogen separation method is not particularly limited as long as a partial pressure difference of hydrogen as a driving force is obtained, but the lower limit of the gas pressure in the space A is usually at least atmospheric pressure, preferably at least 0.11 MPa, more preferably 0. .12 MPa, more preferably 0.15 MPa, while the upper limit is usually 5 MPa or less, preferably 4 MPa or less, more preferably 3 MPa, and even more preferably 1 MPa or less. On the other hand, the lower limit of the pressure in the space B on the permeate side is usually 0 MPa or more, preferably 0.00001 MPa or more, more preferably 0.0001 MPa or more, and further preferably 0.001 MPa or more, while the upper limit is usually 5 MPa or less. The pressure is preferably 4 MPa or less, more preferably 3 MPa, and still more preferably 1 MPa or less. Further, the partial pressure difference of the gas between the space A and the space B is not usually limited, but the lower limit is usually 0.001 MPa or more, preferably 0.002 MPa or more, more preferably 0.005 MPa or more, and further preferably 0.01 MPa. On the other hand, the upper limit is usually 5 MPa or less, preferably 4 MPa or less, more preferably 3 MPa, and still more preferably 1 MPa or less. In the present invention, the pressure (Pa) is an absolute pressure unless otherwise specified.

  In the present invention, the “mixed gas” is a gas including at least “hydrogen” and “a gas that can explode when reacted with hydrogen”. “Oxygen” is an example of a gas that can explode when reacted with hydrogen. The mixed gas may contain an inert gas such as nitrogen, water vapor, or the like in addition to hydrogen and a gas that may explode upon reaction with hydrogen. Examples of the mixed gas include a binary gas of hydrogen and oxygen, a mixed gas of hydrogen and air, a mixed gas of hydrogen, oxygen, and air, and a gas in which water vapor is further added to these gases. .

  It is known that the hydrogen content ratio in the explosion range of hydrogen-air or hydrogen-oxygen is 4.0-75.0 vol%, 3.9-95.8 vol% (High Pressure Gas Safety Association, Hydrogen Security Technology Handbook (1984), Shozo Yanagida, Gas and Steam Explosion Limit (1977)). Therefore, in the case of a mixed gas containing hydrogen and air, the lower limit of the hydrogen content ratio in the mixed gas in the present invention is usually 4.0 vol% or higher, preferably 4.5 vol% or higher, more preferably 5.0 vol%. That's it. On the other hand, the upper limit is usually 75.0 vol% or less, preferably 74.5% vol% or less, more preferably 74.0 vol% or less. In the case of a mixed gas containing hydrogen and oxygen, the lower limit is usually 3.9 vol% or more, preferably 4.5 vol% or more, more preferably 5.0 vol% or more. On the other hand, the upper limit is usually 95.8 vol% or less, preferably 95.5% vol% or less, more preferably 95.0 vol% or less. When the hydrogen content ratio in the mixed gas is within the above range, each is a mixed gas within the explosion range, and therefore, an explosion prevention measure such as a slit material made of an aggregate of fillers according to the present invention is required.

  The slit material may be installed only on the supply gas side (one space sandwiching the molecular sieve membrane), or may be installed on the permeation side (the other space sandwiching the molecular sieve membrane) and the supply gas discharge side.

  In the present invention, when it is difficult to separate and recover 100% of hydrogen from a mixed gas containing hydrogen and oxygen, hydrogen that has not permeated the molecular sieve membrane may be mixed with the exhaust gas on the supply side, and the molecular sieve. Depending on the separation performance of the membrane, a small amount of oxygen can be discharged to the permeate side. In these recovery / discharge-side flow paths, all areas with high explosion risk may be filled with slit material, or some areas with high explosion risk may be filled. It is preferable to fill the material. In some areas where there is a high risk of explosion, it is also possible to use a flame arrester (a safety device that prevents a large fire spread or an explosion in the event of a fire) and other components that have a flame extinguishing function. is there.

  In the hydrogen separation method according to the present invention, the mixed gas flows through the slits of the slit material and reaches the molecular sieve membrane. The slit material is a member that allows gas to flow and permeate in the direction from one to the other and the direction intersecting the direction by having a slit. Any aggregate of fillers having gaps may be used. Details will be described later.

  Among the mixed gas containing hydrogen supplied to the slit of the slit material, hydrogen easily permeates the molecular sieve membrane, but other gases other than hydrogen hardly penetrate the molecular sieve membrane and remain in the slit material. . Thereby, hydrogen can be selectively separated from the mixed gas in the slit material. The molecular sieving membrane in this case is a membrane that selectively permeates molecules by molecular sieving ability, and may be any membrane that has a higher hydrogen permeability than other gases. Details will be described later.

  Thus, in the hydrogen separation method according to the present invention, the mixed gas containing hydrogen is circulated into the slits of the slit material made of the aggregate of fillers, and hydrogen is passed from the slits through the molecular sieve membrane. A separation process is performed selectively. That is, according to the hydrogen separation method according to the present invention, a gas mixture containing hydrogen is supplied to a slit material having a predetermined slit, and hydrogen is selectively separated therefrom through a molecular sieve membrane. In addition, hydrogen can be efficiently separated, and explosion due to the reaction of the mixed gas can be prevented without using a diluent gas such as nitrogen.

2. Hydrogen separation device A hydrogen separation device capable of implementing the above-described hydrogen separation method will be described.

  FIG. 2 is a diagram schematically showing a hydrogen separation apparatus according to an embodiment of the present invention. As shown in FIG. 2, the hydrogen separator includes a hydrogen separator 50 having a slit material 20 having a plurality of slits made of an aggregate of fillers and a molecular sieve membrane 10 covering the outside of the slit material 20. It has. In the hydrogen separator, a mixed gas containing hydrogen can be supplied into the slit material 20 in the hydrogen separator 50 through the inlet 1, and the gas (hydrogen) that has permeated the molecular sieve membrane in the mixed gas. Is recovered from the recovery port 2, and the gas that has not permeated through the molecular sieve membrane 10 is discharged from the discharge port 3. In the present invention, a very small amount of gas (for example, oxygen or water vapor) other than hydrogen that has passed through the molecular sieve membrane 10 can also be recovered from the recovery port 2. In the present invention, when it is difficult to separate and recover 100% of hydrogen from the mixed gas, hydrogen that has not permeated the molecular sieve membrane 10 can also be discharged from the discharge port 3.

  In the hydrogen separator 50, all of one end (end portion on the introduction port 1 side) and the other end (end portion on the discharge port 3 side) of the slit material 20 may not be covered with the molecular sieve membrane 10. The supplied mixed gas can be discharged out of the system from the other end. On the other hand, the outer surface of the slit material (the surface on the side where the recovery port 2 is located) is covered with the molecular sieve membrane 10, and among the mixed gas flowing through the slit material 20 via the molecular sieve membrane 10, in particular. Hydrogen can be selectively permeated.

  The molecular sieve film 10 is a thin film that covers the outer surface of the slit material 20. The form of the molecular sieve membrane 10 is not particularly limited as long as the molecular sieve ability can be appropriately exhibited.

  In the present invention, the molecular sieve membrane 10 is preferably any one of a zeolite membrane, a silica membrane, and a carbon membrane, or a combination thereof. Since these have higher hydrogen permeance than oxygen, they can function appropriately as a membrane for separating hydrogen from a mixed gas containing hydrogen, particularly a mixed gas containing hydrogen and oxygen.

  Here, when a zeolite membrane is used as the molecular sieve membrane 10, the zeolite is preferably an aluminosilicate, but Ga, Fe, B, Ti, Zr, Sn, Zn instead of Al unless the membrane performance is greatly impaired. A metal element such as Ga, Fe, B, Ti, Zr, Sn, Zn, and P may be included together with Al. The skeleton of the crystalline zeolite forming the pores of the zeolite membrane is preferably an oxygen 8-membered ring or less. Examples of the zeolite structure include AEI, AFG, ANA, CHA, DDR, EAB, ERI, ESV. , FAR, FRA, GIS, ITE, KFI, LEV, LIO, LOS, LTA, LTN, MAR, PAU, RHO, RTH, SOD, STI, TOL, UFI, and the like. Among these, it is preferable to use a membrane composed of AEI, CHA, DDR, ERI, KFI, LEV, PAU, RHO, RTH, SOD, LTA, UFI type zeolite, and CHA, DDR, RHO, SOD type zeolite. More preferably, a constructed film is used.

  Among them, the skeleton of the crystalline zeolite forming the pores of the zeolite membrane is preferably a ring having an oxygen 8-membered ring or less, and in particular, a membrane composed of CHA-type zeolite is preferably used. When such a zeolite membrane is used, hydrogen can be more efficiently separated from the mixed gas.

  In the present specification, the value of n of the zeolite having an oxygen n-membered ring is such that the number of oxygen elements is the largest among the pores composed of the zeolite skeleton and the T element (elements other than oxygen constituting the skeleton). Point to something big. Moreover, the structure of a zeolite is shown by the code | symbol which prescribes | regulates the structure of the zeolite which International Zeolite Association (IZA) defines as above-mentioned.

  The molecular sieve membrane 10 may be subjected to a treatment for more effectively controlling the opening diameter, and in this case, hydrogen can be separated more efficiently. Further, the molecular sieve membrane 10 may be subjected to a treatment for improving the hydrophobicity (see, for example, a silylation treatment described in International Publication No. 2013/125661 pamphlet). When such a zeolite membrane is used, hydrogen can be separated more efficiently even when the mixed gas containing hydrogen further contains water vapor. If both functions are combined, hydrogen can be further efficiently separated.

  Further, since the CHA-type zeolite can synthesize a high-silica zeolite membrane and is relatively hydrophobic in the zeolite, a mixed gas containing hydrogen and oxygen generated by photolysis of water and water vapor is used as a molecular sieve. Also when transported to the membrane 10, it is also preferable from the viewpoint of suppressing the permeation of water vapor and maintaining the hydrogen permeability.

  In addition, when synthesizing a zeolite membrane, an organic template (structure directing agent) can be used as necessary. However, there is no particular limitation as long as it is a template capable of producing a target zeolite structure. If synthesis is possible, it may not be used.

  When a silica membrane is used as the molecular sieve membrane 10, the silica content in the silica membrane is not particularly limited as long as the effects of the present invention are not significantly impaired. For example, all positive elements including silicon in the silicon oxide composition The ratio of silicon to is usually 50 mol% or more.

  The silica film is formed on the porous substrate by a sol-gel method, a CVD method, a polymer precursor method, or the like. In the sol-gel method, a silica film can be formed by reacting a metal alkoxide with water on a porous substrate described later to form a gel from hydrolysis and dehydration condensation. In the case of a counter diffusion CVD method, for example, in the case of a porous cylindrical base material, oxygen is circulated on the inner side, a silica source is circulated on the outer side, and an amorphous silica layer is vapor-deposited in the base material pores. A membrane can be formed. In the polymer precursor method, a silica precursor such as alkoxysilane or polysilazane is coated on a porous substrate, and then heat treatment is performed to form a silica film.

  When a carbon film is used as the molecular sieve film 10, the carbon film precursor solution is dip-coated (dip-coated) on the porous substrate, heat-treated at about 600 to 800 ° C., and dried to obtain a carbon film. Examples of the carbon film precursor include aromatic polyimide, polypyrrolone, polyfurfuryl alcohol, polyvinylidene chloride, phenol resin, lignin derivative, wood tar, bamboo tar, and the like. Moreover, as a solvent, organic solvents, such as tetrahydrofuran, acetone, methanol, ethanol, N-methylpyrrolidone, can be used conveniently.

  The film thickness of the molecular sieve membrane 10 is not particularly limited, but is usually 0.01 μm to 30 μm, preferably 0.01 μm to 20 μm, more preferably 0.01 μm to 10 μm for a zeolite membrane, and from a single layer for a silica membrane. Or a film composed of two or more layers, and the thickness is usually 1 nm to 10 μm, preferably 1 nm to 5 μm, more preferably 1 nm to 1 μm, and the carbon film is 0.05 μm to 5 mm, preferably Although it is 0.1 μm to 2.5 mm, more preferably 0.1 μm to 500 μm, it is preferable that the film thickness is thin as long as the film performance is not greatly impaired. The film thickness can be measured using a scanning electron microscope (SEM).

  The method for forming the molecular sieve film 10 on the surface of the slit material 20 is not particularly limited. For example, by applying a method of forming a molecular sieve membrane on the surface of an inorganic porous substrate as described in International Publication No. 2013/125660, the molecular sieve membrane 10 can be easily formed on the surface of the slit material 20. Can be formed. That is, (1) a method of fixing a substance capable of constituting the molecular sieve membrane 10 to the surface of the slit material 20 with a binder or the like, and (2) a slit material in a slurry or solution in which a substance capable of constituting the molecular sieve membrane 10 is dispersed. (3) A substance (in particular, zeolite or silica) that can constitute the molecular sieve film 10 on the surface of the slit material 20 is formed into a film. The method of generating is mentioned.

  In the present invention, in the slit material 20 made of an aggregate of fillers, it is preferable that the longest gap diameter of the slit is not more than a predetermined length.

  FIG. 3 shows an example of a cross section of a continuous slit formed by the slits provided in the slit material 20. FIG. 3A is a continuous slit constituted by a slit having a gap diameter not larger than a predetermined length, and FIG. 3B is constituted by a slit having a part of the gap diameter longer than the predetermined length. Is a continuous slit.

  In FIG. 3A, all the slits have a gap diameter of a predetermined length or less. That is, no gap has a gap whose gap diameter exceeds a predetermined length in any part. When such a slit material consisting only of slits is used, even if a mixed gas containing hydrogen is circulated, explosion due to the reaction of the mixed gas can be prevented.

  On the other hand, in FIG. 3B, there are portions (portions X and Y) in which the gap diameter of the slit exceeds a predetermined length. When a slit material including such a slit is used, if a mixed gas containing hydrogen is circulated, there is a possibility that explosion due to the reaction of the mixed gas cannot be completely prevented.

  According to the knowledge of the present inventors, the upper limit of the longest gap diameter of the slit is preferably 1700 μm or less, more preferably 1200 μm or less, further preferably 600 μm or less, particularly preferably 450 μm or less, and most preferably 310 μm or less. . In particular, in a hydrogen / oxygen mixed gas, the thickness is preferably 600 μm or less, more preferably 450 μm or less, and even more preferably 310 μm or less. On the other hand, the lower limit is preferably 80 μm or more, more preferably 110 μm or more, further preferably 160 μm or more, and particularly preferably 210 μm or more. If the longest gap diameter of the narrow gap is within this range, explosion can be prevented and a mixed gas containing hydrogen can be easily circulated to selectively separate hydrogen through a molecular sieve membrane. In the present invention, since the slit material is composed of an aggregate of fillers, the gap diameter of the slit can be easily reduced.

  Hereinafter, specific examples of the hydrogen separator will be described.

2.1. Hydrogen separator 50a
4 and 5 schematically show the hydrogen separator 50a. 4A is a diagram schematically showing the internal structure of the hydrogen separator 50a, FIG. 4B is a diagram schematically showing a hydrogen separation mechanism by the hydrogen separator 50a, and FIG. FIG. 5 is a diagram schematically showing the appearance of the hydrogen separator 50a, and FIG. 5B is a diagram schematically showing the IXB-IXB cross section of FIG. 5A.

  As shown in FIGS. 4 and 5, in the hydrogen separator 50 a, fillers 20 a, 20 a,... Are filled in a space partitioned by a substantially cylindrical molecular sieve membrane 10. That is, in the hydrogen separator 50a, the slit material is composed of an aggregate of fillers 20a, 20a,..., And the molecular sieve membrane 10 covers the outside of the slit material.

  In such a slit material, the size of the filler 20a is preferably within a certain range. In other words, if the average particle size of the filler is too large, the gaps formed in the slit material will be large, and there may be too many slits with a gap diameter exceeding a predetermined length, preventing explosion. There is a risk that it will not be possible. On the other hand, if the average particle size of the filler is too small, explosion can be prevented, but the pressure loss before and after the gas passing through the slit material increases, making it difficult to distribute the mixed gas into the slit material. As a result, the processing speed of hydrogen separation may be reduced.

  The inventors of the present invention have found that the average particle diameter of the filler and the longest gap diameter of the narrow gap substantially coincide. That is, the gap diameter can be easily reduced by using a filler having a small average particle diameter. In this regard, according to the knowledge of the present inventors, the lower limit of the average particle diameter of the filler is preferably 80 μm or more, more preferably 110 μm or more, still more preferably 160 μm or more, and particularly preferably 210 μm or more. On the other hand, the upper limit is preferably 1700 μm or less, more preferably 1200 μm or less, further preferably 600 μm or less, particularly preferably 450 μm or less, and most preferably 310 μm or less. If the average particle size of the filler is within this range, explosion can be prevented more appropriately, and a mixed gas can be easily circulated to obtain a slit material that selectively separates hydrogen through a molecular sieve membrane. be able to.

  Moreover, in this invention, you may use a filler in combination of 2 or more types from which a magnitude | size differs. When two or more kinds of fillers having different sizes are used in combination, more inexpensive fillers can be used by increasing choices of fillers.

  The filler 20a may be an inorganic filler, an organic filler, or a combination thereof. Examples of the inorganic filler include ceramic beads such as glass beads, zirconia beads, and mullite beads, metal beads, metal mesh, and fragments thereof. Examples of the organic filler include resin beads or fragments thereof. In the present application, a “bead” includes a hole without a hole (simple spherical shape as illustrated).

  Of these, glass beads, zirconia beads, mullite beads and other ceramic beads, or fragments thereof are preferred from the viewpoint of low reactivity with hydrogen and oxygen, low cost and excellent handling properties. Moreover, it is also preferable to use a metal bead, a metal mesh, or these fragments from a viewpoint that heat conductivity is good and the heat which generate | occur | produces in the process in which the mixed gas containing hydrogen explodes is escaped and it is hard to make it explode.

2.2. Hydrogen separator 50b
FIG. 6 schematically shows the hydrogen separator 50b. FIG. 6 (A) is a diagram schematically showing the appearance of the hydrogen separator 50b, and FIG. 6 (B) is a diagram schematically showing the XB-XB cross section of FIG. 6 (A). In FIG. 6, the same members as those in FIGS. 4 and 5 are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

  As shown in FIG. 6, in the hydrogen separator 50b, the outer side of the substantially cylindrical inorganic porous substrate 30 is covered with the molecular sieve membrane 10, while the inner space is filled with fillers 20a, 20a,. . In the hydrogen separator 50b as well, the slit material is composed of an aggregate of fillers as in the hydrogen separator 50a. That is, in the hydrogen separator 50 b, the molecular sieve membrane 10 covers the outside of the slit material via the inorganic porous substrate 30.

  The hydrogen separator 50b can be easily manufactured by the following method. That is, (1) a method of fixing a substance capable of constituting the molecular sieve membrane 10 to the surface of the inorganic porous substrate 30 with a binder or the like, and (2) inorganic porous in a slurry in which a substance capable of constituting the molecular sieve membrane 10 is dispersed. A method of impregnating the base material 30 to fix the substance on the surface of the inorganic porous base material 30; (3) a substance capable of constituting the molecular sieve membrane 10 on the surface of the inorganic porous base material 30 (in particular, zeolite or After obtaining a composite having excellent strength by, for example, a method of forming (silica) into a film (see, for example, International Publication No. 2013/125660 pamphlet), the inside of the composite is filled with the filler 20a. Thus, the hydrogen separator 50b can be easily manufactured.

  Thus, the inorganic porous substrate 30 functions as a support that supports the molecular sieve membrane 10. The material which comprises the inorganic porous base material 30 is not specifically limited, Various materials, such as glass, ceramics, a metal, a carbon molded object, or resin, are applicable. In the case of a ceramic base material, any porous inorganic substance having a chemical stability capable of crystallizing zeolite in a film form on the surface or the like may be used. Specific examples include ceramic sintered bodies such as silica, α-alumina, γ-alumina, mullite, zirconia, titania, yttria, silicon nitride, and silicon carbide.

  Among these, silica, alumina (α-alumina, γ-alumina) and mullite are preferable, and alumina is more preferable. The reason why alumina is preferable is that the alumina porous substrate supports the molecular sieve membrane with high adhesion.

  In the present invention, the inorganic porous substrate 30 itself does not need to have molecular sieving ability. The inorganic porous substrate 30 is provided with fine pores (holes, voids, slits) communicating from the inner wall side toward the outer wall side. A well-known inorganic porous substrate 30 having pores can be used.

  The lower limit of the porosity of the inorganic porous substrate 30 is usually 20% or more, preferably 25% or more, more preferably 30% or more, while the upper limit is usually 80% or less, preferably 60% or less. Preferably it is 50% or less. The lower limit of the average pore diameter of the inorganic porous substrate 30 is usually 0.01 μm or more, preferably 0.05 μm or more, more preferably 0.1 μm or more, while the upper limit is 20 μm or less, preferably 10 μm or less. More preferably, it is 5 μm or less. With the inorganic porous substrate 30 having such pores, the molecular sieve membrane 10 can be adequately supported with sufficient strength, and the hydrogen that has passed through the molecular sieve membrane 10 can be appropriately applied to the outer wall side. Transmission is possible at a sufficient speed. Note that the porosity and average pore diameter of the inorganic porous substrate 30 can be easily specified by mercury porosimetry, cross-sectional scanning electron microscope (SEM) observation, and the like. The porosity can also be calculated from volume and mass using true specific gravity.

2.3. Hydrogen separator 50c
The hydrogen separators 50a and 50b described above each have a form in which the molecular sieve membrane covers the outside of the slit material. However, the present invention is not limited to this form. 7 and 8 schematically show the hydrogen separator 50c. FIG. 7A is a diagram schematically showing the internal structure of the hydrogen separator 50c, FIG. 7B is a diagram schematically showing a hydrogen separation mechanism by the hydrogen separator 50c, and FIG. FIG. 8 is a diagram schematically showing an appearance of a hydrogen separator 50c, and FIG. 8B is a diagram schematically showing a cross section taken along line XIIIB-XIIIB of FIG. 8A. 7 and 8, members similar to those in FIGS. 4 to 6 are denoted by the same reference numerals, and description thereof is omitted as appropriate.

  As shown in FIGS. 7 and 8, in the hydrogen separator 50 c, the substantially cylindrical molecular sieve membrane 10 is accommodated inside the substantially cylindrical outer wall material 11, and the space between the outer wall material 11 and the molecular sieve membrane 10 is filled. Agents 20a, 20a,... Are filled to form a slit material. That is, in the hydrogen separator 50c, the molecular sieve membrane 10 covers the inside of the slit material. According to the hydrogen separator 50c, hydrogen can be selectively permeated through the molecular sieve membrane 10 in the mixed gas supplied into the slit material. Thus, the molecular sieve membrane 10 should just be provided so that the outer side or inner side of a slit material may be covered.

2.4. Hydrogen separator 50d
All of the hydrogen separators 50a to 50c described above have a form in which a molecular sieve membrane is formed in a cylindrical shape. However, the present invention is not limited to this form. FIG. 9 schematically shows a hydrogen separator 50d. As shown in FIG. 9, the hydrogen separator 50d includes an outer package 12 having a groove, a slit material 20 filled in the groove of the outer package 12, a molecular sieve membrane 10 covering the surface of the slit material 20, It has. That is, in the hydrogen separator 50 d, the slit material 20 is filled in the space defined by the molecular sieve membrane 10 and the outer package 12, and the molecular sieve membrane 10 covers the upper portion of the slit material 20.

  As shown in FIG. 9, the mixed gas containing hydrogen supplied from one end of the groove into the slit material 20 flows through the slit of the slit material 20 and reaches the molecular sieve membrane 10. Among the mixed gas, hydrogen permeates the molecular sieve membrane 10 and is recovered from the membrane surface to the outside of the system, while gas that has not permeated the molecular sieve membrane 10 is discharged from the other end of the groove to the outside of the system.

  As described above, according to a hydrogen separator having a hydrogen separator such as the hydrogen separators 50a to 50d, hydrogen can be efficiently separated using a molecular sieve membrane, and hydrogen can be used without using a diluent gas. Explosion due to the reaction between oxygen and oxygen can also be prevented.

  In the above description, various specific examples have been described for the hydrogen separator. However, members other than the hydrogen separator in the hydrogen separator according to the present invention are not particularly limited. For example, as shown in FIG. 2, an inlet 1 for appropriately introducing a mixed gas containing hydrogen into the hydrogen separator 50, a recovery port 2 for recovering hydrogen separated from the hydrogen separator, and In addition to the discharge port 3 for discharging the gas that did not permeate the molecular sieve membrane in the hydrogen separator, a circulation channel for introducing the gas discharged from the discharge port 3 into the hydrogen separator 50 again is provided. It may be.

  In the above description, the hydrogen separator is described as including one hydrogen separator, but the present invention is not limited to this embodiment. A hydrogen separator may be configured by stacking a plurality of hydrogen separators.

  In the above description, the hydrogen separators 50a to 50d having specific forms have been described. However, in the present invention, the form (shape, size, material, etc.) of the hydrogen separator is implemented by the hydrogen separation method according to the present invention. It can be changed as appropriate within the possible range.

  In the above description, the hydrogen separators 50a to 50d provided in the hydrogen separator have been described independently. However, in the present invention, members related to the hydrogen separators 50a to 50d may be combined.

  In the above description, the supply source of the mixed gas containing hydrogen is not particularly limited, but in the present invention, it is a mixed gas containing hydrogen and oxygen generated by a water splitting reaction using a photocatalyst. Is preferred. For example, in FIG. 2, a mode in which a photocatalytic reactor (a reactor capable of performing a water splitting reaction using a photocatalyst) is connected to the inlet 1 and a mixed gas containing hydrogen and oxygen is supplied into the hydrogen separator 50 is preferable. In this case, the type of the photocatalyst is not particularly limited, and any particle or molded body may be used as long as it is a photocatalyst that can decompose water into hydrogen and oxygen using sunlight.

  In the above description, the composition ratio in the mixed gas containing hydrogen is not particularly limited. However, in the present invention, the mixed gas is preferably a mixed gas having a hydrogen content within the explosion range. Particularly preferred is the case of hydrogen / oxygen = 2/1 generated by the decomposition reaction. . Note that the mixed gas produced by the water splitting reaction by the photocatalyst may contain water vapor or the like in addition to hydrogen and oxygen.

  In the above description, the embodiment in which the filler is “spherical” is described as an example, but the present invention is not limited to this embodiment. In addition to cylindrical fillers, prismatic fillers, and oblong fillers, fine powder fillers can also be used. However, it is preferable to use a spherical filler from the viewpoint that the gap diameter can be easily controlled during the production of the slit material.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not restrict | limited by a following example, unless the summary is exceeded.

  In this example, the average particle diameter of beads used as <1> filler was measured, and the gap diameter of the slits existing in the slit material composed of the aggregate of fillers was analyzed and measured. <2> A flame extinction test was performed when the average particle size of the beads was changed. <3> A hydrogen separator shown in FIGS. 2 and 6 was produced. That is, beads are filled as a filler inside a molecular sieve membrane (CHA-type zeolite membrane, manufactured by Mitsubishi Chemical Corp.) formed on a substantially cylindrical (9 mm inner diameter, 12 mm outer diameter) porous alumina tube to form a slit material. did. The permeation behavior of the gas that permeates the molecular sieve membrane and the pressure loss before and after the slit material when the average particle diameter of the beads was changed were evaluated.

<1> Measurement of average particle size of beads and analysis method of slit (1) Measurement of average particle size of beads

  For the beads used for the measurement, glass beads made by Toshin Riko Co., Ltd., glass beads made by Fuji Seisakusho Co., Ltd., and mullite beads described in “TGK Scientific Instruments General Catalog Research, Experiments and Inspections 2013-2014” on page 294 It was. Table 1 shows the catalog number of the glass beads used in the examples and the approximate bead diameter distribution range standard described in the catalog.

  The average particle diameter of the beads is measured as a median diameter on a volume basis by a laser diffraction / scattering particle size distribution measuring apparatus. Each bead was measured twice using the following apparatus, and the average value of the obtained median diameters was defined as the average particle diameter. The measurement results are shown in Table 1.

  Hereinafter, the particle size distribution apparatus used for the measurement is described for each bead name.

(No. 007)
Glass beads No. 007 (the standard of the bead diameter range described in the catalog is 0.063 to 0.088 mm), using a laser diffraction / scattering particle size distribution measuring apparatus LA-500 manufactured by HORIBA, Ltd., using water as a dispersion medium and refraction of the sample. The particle size distribution was measured with an index = 1.51 and a refractive index of the dispersion medium = 1.333. The average particle size results are shown in Table 1.

(No. 020)
Glass beads No. 020 (the standard of the bead diameter range described in the catalog is 0.177 to 0.250 mm) is a laser diffraction / scattering particle size distribution measuring apparatus LA-960 manufactured by HORIBA, Ltd. The measurement was carried out at a rate of 1.510-0.000i, a refractive index of the dispersion medium of 1.333-0.000i, and a circulation speed range of 8. The average particle size results are shown in Table 1.

(FGB # 60)
Glass beads FGB # 60 (the standard of the bead diameter range described in the catalog is 0.250 to 0.355 mm) Measurements were performed in the same manner as 020 glass beads. The average particle size results are shown in Table 1.

(No. 040)
Glass beads No. No. 040 (the standard of the bead diameter range described in the catalog is 0.350 to 0.500 mm) is No. Measurements were performed in the same manner as 020 glass beads. The average particle size results are shown in Table 1.

(No. 060)
Glass beads No. 060 (the standard of the bead diameter range described in the catalog is 0.500 to 0.710 mm) is No. Measurements were performed in the same manner as 020 glass beads. The average particle size results are shown in Table 1.

(No. 080)
Glass beads No. 080 (the standard of the bead diameter range described in the catalog is 0.710 to 0.990 mm) is No. Measurements were performed in the same manner as 020 glass beads. The average particle size results are shown in Table 1.

(No. 1)
Glass beads No. 1 (the standard of the bead diameter range described in the catalog is 0.991 to 1.397 mm) is No. 1. Measurements were performed in the same manner as 020 glass beads. The average particle size results are shown in Table 1.

(Mullite)
Mullite beads “Mullite” (the standard of the bead diameter range described in the catalog is 1.74 mm on average) is No. Measurements were performed in the same manner as 020 glass beads. The average particle size results are shown in Table 1.

(No. 2)
Glass beads No. No. 2 (the standard of the bead diameter range described in the catalog is 1.500 to 2.500 mm). Measurements were performed in the same manner as 020 glass beads. The average particle size results are shown in Table 1.

  From this result, it can be seen that the average particle size of the beads is within the range of the standard described in the catalog.

(2) Analysis method of slit Preparation method of sample used for measurement:
A slit material for measurement was formed by filling beads inside the acrylic tube. The beads were filled until the volume did not change in the acrylic tube. At that time, the filling rate of the glass beads was determined from the true specific gravity, filling weight, and occupied volume of the glass beads.

  A three-dimensional image obtained by performing X-ray CT analysis on the sample under the following conditions, image analysis software (product name “3D trabecular structure measurement software TRI / 3D-BON-FCS64” manufactured by Ratok System Engineering Co., Ltd.) And analyzed.

<X-ray CT analysis conditions>
X-ray CT analyzer: Three-dimensional measurement manufactured by Yamato Scientific Co., Ltd. X-ray CT analysis was performed under the conditions shown in Table 2 using TDM1000-II (2K). As will be described later, the photographing was performed so as to include the entire wall surface of the acrylic tube. X-ray CT data was obtained as cross-sectional three-dimensional image data (an acrylic tube corresponds to the molecular sieve membrane (10)) as shown in FIG.

<Image analysis method for images obtained by X-ray CT>
The obtained X-ray CT data was subjected to image analysis using the image analysis software manufactured by Ratok System Engineering Co., Ltd., and a slit having a three-dimensional slit having a predetermined gap length or more was extracted. When determining the boundary between voids and particles by binarization, the porosity of the sample and the void ratio at the time of image processing match, the slit of the X-ray CT image, and the slit of image processing By matching, it was judged that the slits of the sample could be appropriately extracted.

  If there is a void exceeding 310 μm, the continuous void is extracted, the smallest rectangular solid that can encompass the entire three-dimensional continuous slit is specified, and the longest diagonal line of the rectangular solid is 310 μm. It was measured as the continuous length of voids exceeding (FIG. 10). In addition, when the space | gap exceeding 310 micrometers is not extracted, suppose that there is no space | gap exceeding 310 micrometers.

  For each sample, the longest gap diameter of the gap, the presence or absence of a gap with a gap diameter of more than 310 μm, and the continuous length of the slit with a gap diameter of more than 310 μm were measured. Table 3 shows the measurement results.

  From this result, it can be seen that the longest gap diameter of the slit and the average particle diameter of the beads are substantially the same length. In addition, the continuous length of the slit having a gap diameter of more than 310 μm is indicated by the beads No. It can be seen that even 060 is as short as 2 mm or less.

<2> Flame extinction test

  While changing the average particle size of the beads, an anti-flame test was conducted. Specifically, as shown in FIG. 11, a flame extinguishing test facility comprising a first combustion chamber, a flame extinguishing element, and a second combustion chamber was used.

  A flame is generated in the first combustion chamber filled with a hydrogen / air mixed gas having a composition ratio of 29.5 / 70.5 vol% under normal temperature and normal pressure conditions, and the flame propagates to the second combustion chamber through the extinguishing element. Whether or not it propagates was examined from changes in temperature and pressure. The reason why the hydrogen / air composition ratio was 29.5 / 70.5 vol% is that this composition ratio almost corresponds to the composition ratio showing the maximum value of the explosion pressure of the hydrogen / air mixed gas ( Schroeder et al., International Conference on Hydrogen Safety Vol. 120001, p1-12 (2005)).

  The flame extinguishing element was produced by filling beads in a container having a diameter of 60 mm and a height of 35 mm, which was closed up and down with a 20 μm mesh wire netting.

  The results for each sample are shown in Table 4. The case where the flame propagated (not extinguished) was set as “×”, and the case where the flame did not propagate (extinguished) was set as “◯”.

From this result, it can be seen that the hydrogen / air mixed gas can be extinguished by using an aggregate of fillers having an average particle diameter of 1653 μm. In addition, when the literature values of the flame extinguishing diameter (hydrogen / air: 860 μm, hydrogen / oxygen: 310 μm) are used, the hydrogen / oxygen mixed gas can be extinguished by using an aggregate of fillers having an average particle diameter of about 600 μm. it is conceivable that.

<3> Gas separation evaluation

<Hydrogen separator>
As the hydrogen separator, two types of CHA-type zeolite membrane composites in which a CHA-type zeolite membrane was formed on the outside of the inorganic porous support by hydrothermal synthesis were used.

<Porous alumina support-CHA type zeolite membrane composite 1>
A porous alumina tube (outer diameter 12 mm, inner diameter 9 mm, length 80 mm) is used as the inorganic porous support, and after seed crystals are supported on the side of the porous alumina support, CHA-type zeolite is directly hydrothermally synthesized. Thus, a porous alumina support-CHA type zeolite membrane composite 1 was produced.

  A reaction mixture for hydrothermal synthesis for synthesizing a CHA-type zeolite membrane on a porous alumina support and a seed crystal previously supported on the porous alumina support were prepared as follows. A CHA-type zeolite membrane composite 1 was obtained.

<Synthesis of aqueous reaction mixture 1>
A mixture of 10.5 g of 1 mol / L-NaOH aqueous solution (manufactured by Kishida Chemical Co., Ltd.), 7.0 g of 1 mol / L-KOH aqueous solution (manufactured by Kishida Chemical Co., Ltd.) and 100.6 g of demineralized water is mixed with aluminum hydroxide (Al ₂ O ₍ 33.5% by mass, manufactured by Aldrich) 0.88 g was added, followed by stirring to obtain a transparent solution. As an organic template, 2.36 g of an aqueous solution of N, N, N-trimethyl-1-adamantanammonium hydroxide (hereinafter referred to as “TMADAOH”) (containing 25% by mass of TMADAOH, manufactured by Seychem) was added, and After adding 10.5 g of colloidal silica (Snowtex 40, Nissan Chemical Co., Ltd.), the mixture was stirred for 2 hours to obtain an aqueous reaction mixture.

The composition (molar ratio) of the aqueous reaction mixture 1 was SiO ₂ / Al ₂ O ₃ / NaOH / KOH / H ₂ O / TMADAOH = 1 / 0.066 / 0.15 / 0.1 / 100 / 0.04. , SiO ₂ / Al ₂ O ₃ = 15.

  As the ceramic support, a porous alumina tube (outer diameter 12 mm, inner diameter 9 mm) was cut to a length of 80 mm, washed with water with an ultrasonic cleaner and dried.

<Method of synthesizing seed crystal>
Seed crystal 1 used in producing the CHA-type zeolite membrane composite 1, as Cataloid SI-30 of the Si source JGC Catalysts and Chemicals Ltd., gel composition (molar _{ratio) SiO 2 / Al 2 O 3} / NaOH / KOH / H ₂ O / TMADAOH = 1 / 0.033 / 0.1 / 0.06 / 20 / 0.07, SSZ-13 particles as seed crystals, 2% by mass with respect to the SiO ₂ component, A CHA-type zeolite obtained by hydrothermal synthesis at 160 ° C. for 2 days for crystallization and filtration, washing with water and drying was used.

The support was immersed in a slurry in which the seed crystal was dispersed in about 0.3% by mass of water for a predetermined time, and then dried at 100 ° C. for 5 hours or more to adhere the seed crystal. The mass of the attached seed crystal was about 0.7 g / m ² .

<Synthesis Method of Porous Alumina Support-CHA Type Zeolite Membrane Composite 1>
The support to which the seed crystals were attached was immersed in a Teflon (registered trademark) inner cylinder (200 ml) containing the aqueous reaction mixture in the vertical direction, and the autoclave was sealed, and left standing at 180 ° C. for 18 hours. And heated under autogenous pressure. After the elapse of a predetermined time, the support-zeolite membrane composite was taken out of the reaction mixture after being allowed to cool, washed, and then dried at 100 ° C. for 5 hours or more.

This membrane composite was baked in an electric furnace at 500 ° C. for 5 hours in air. The mass of the CHA-type zeolite crystallized on the support, determined from the difference between the mass of the membrane composite after firing and the mass of the support, was 124 g / m ² .

One end of this cylindrical tubular zeolite membrane composite is sealed, the other end is connected to a vacuum line of 5 kPa (absolute pressure), the inside of the tube is depressurized, and the mass flow installed between the vacuum line and the zeolite membrane composite It was 17L / (m < ² > * h) when the amount of permeation | transmission of the air which flows with a meter was measured.

<Porous alumina support-CHA type zeolite membrane composite 2>
A porous alumina tube (outer diameter 12 mm, inner diameter 9 mm, length 80 mm) is used as the inorganic porous support, and after seed crystals are supported on the side of the porous alumina support, CHA-type zeolite is directly hydrothermally synthesized. Thus, a porous alumina support-CHA type zeolite membrane composite 2 was produced.

  A reaction mixture for hydrothermal synthesis for synthesizing a CHA-type zeolite membrane on a porous alumina support and a seed crystal previously supported on the porous alumina support were prepared as follows. A CHA-type zeolite membrane composite 2 was obtained.

<Synthesis of aqueous reaction mixture 2>
Aluminum hydroxide (Al ₂ O ₃ 53) mixed with 1.4 g of 1 mol / L-NaOH aqueous solution (manufactured by Kishida Chemical Co., Ltd.), 5.8 g of 1 mol / L-KOH aqueous solution (manufactured by Kishida Chemical Co., Ltd.) and 114 g of demineralized water. 0.5 mass% (manufactured by Aldrich Co.) was added, and then stirred to obtain a transparent solution. As an organic template, 2.4 g of TMADAOH aqueous solution (containing 25% by mass of TMADAOH, manufactured by Seychem) was added, and 10.8 g of colloidal silica (Snowtex 40 manufactured by Nissan Chemical Co., Ltd.) was further added, followed by stirring for 1 hour. An aqueous reaction mixture was obtained.

The composition (molar ratio) of the aqueous reaction mixture 2 was SiO ₂ / Al ₂ O ₃ / NaOH / KOH / H ₂ O / TMADAOH = 1 / 0.014 / 0.02 / 0.08 / 100 / 0.04. SiO ₂ / Al ₂ O ₃ = 70.

  As the ceramic support, a porous alumina tube (outer diameter 12 mm, inner diameter 9 mm) was cut to a length of 80 mm, washed with water with an ultrasonic cleaner, and dried.

As a seed crystal, the gel composition (molar ratio) of SiO ₂ / Al ₂ O ₃ / NaOH / KOH / H ₂ O / TMADAOH = 1 / 0.033 / 0.1 / 0.06 / 40 / 0.07, A CHA-type zeolite obtained by hydrothermal synthesis at 160 ° C. for 2 days for crystallization, followed by filtration, washing with water and drying was used.

The support was immersed in a dispersion of the seed crystal in about 1% by mass of water for a predetermined time, and then dried at 140 ° C. for 1 hour or longer to attach the seed crystal. The mass of the attached seed crystal was about 1 g / m ² .

<Synthesis Method of Porous Alumina Support-CHA Type Zeolite Membrane Composite 2>
The support to which the seed crystals were attached was immersed in a Teflon (registered trademark) inner cylinder (200 ml) containing the aqueous reaction mixture in the vertical direction, and the autoclave was sealed, and left standing at 180 ° C. for 18 hours. And heated under autogenous pressure. After the elapse of a predetermined time, the support-zeolite membrane composite was taken out of the reaction mixture after being allowed to cool, washed, and dried at 120 ° C. for 1 hour or longer.

This membrane composite was baked in the air at 500 ° C. for 14 hours in an electric furnace manufactured by Yamato Scientific Co., Ltd. At this time, the rate of temperature increase and the rate of temperature decrease were both 0.5 ° C./min. The mass of the CHA-type zeolite crystallized on the support, determined from the difference between the mass of the membrane composite after firing and the mass of the support, was 80 g / m ² .

One end of this cylindrical tubular zeolite membrane composite is sealed, the other end is connected to a vacuum line of 5 kPa (absolute pressure), the inside of the tube is depressurized, and the mass flow installed between the vacuum line and the zeolite membrane composite It was 6L / (m < ² > * h) when the permeation | transmission amount of the air which flows with a meter was measured.

<Gas separation evaluation method>
The pressure shown below refers to an absolute pressure unless otherwise specified. When (G) is attached after the pressure unit, the gauge pressure is indicated. The flow rate refers to the standard flow rate (0 ° C., 0.1013 MPa).

  A separation membrane module apparatus shown in FIG. 2 is used to supply a fixed amount of gas into the porous alumina support-CHA type zeolite membrane composite using a mass flow controller, and a back pressure valve installed downstream of the supply gas. The pressure of the supply gas was adjusted, and gas separation evaluation was performed at 80 ° C. or 100 ° C. The permeation side was opened to atmospheric pressure, and the flow rate was measured with a mass flow meter (Brooks Instrument Co., Ltd.).

  When evaluating a mixed gas, the supply gas side uses two types of mass flow controllers (manufactured by Brooks Instruments) to mix hydrogen and nitrogen so that the hydrogen / nitrogen flow ratio is 2/1. The treated gas was used as the supply gas. The component ratio of the permeated gas was determined by gas chromatography (manufactured by Agilent Technologies). The conversion factor of the mixed gas was determined from the component ratio of the gas, the numerical value indicated by the mass flow meter, and the conversion factor of each gas, and the amount of each gas permeation of the mixed gas in the permeated gas was calculated.

  In the examples of the present specification, the conversion factor hardly changes between oxygen and nitrogen (oxygen: 0.99, nitrogen: 1.00), and the dynamic molecular diameter hardly changes ( (Oxygen: 0.35 nm, Nitrogen: 0.36 nm), instead of a mixed gas containing hydrogen and oxygen, a mixed gas containing hydrogen and nitrogen was used.

  Prior to evaluation, in order to remove moisture from the porous alumina support-CHA-type zeolite membrane composite, carbon dioxide was supplied at 135 ° C. and 0.15 MPa (G) at 100 ° C. as a pretreatment, The permeation side was opened to atmospheric pressure, and drying was performed for 1 hour or more until the amount of carbon dioxide permeation became constant.

  When the type and conditions of the supply gas were changed, the measurement was performed after waiting for at least 5 minutes until the gas permeation amount became constant and confirming that the permeation amount was stable.

  The bead No. used when the average particle size was measured. 0.07 (average particle size 72 μm), No. 020 (average particle size 203 μm), FGB # 60 (average particle size 313 μm) No. 0.40 (average particle size 437 μm), No. 0.60 (average particle size 617 μm), No. 0.80 (average particle diameter 903 μm), and No. 1 (average particle diameter 1172 μm) was filled inside the porous alumina support-CHA type zeolite membrane composite 1 or 2 to form a slit material.

  In the case of Examples 1 to 9 and Reference Examples 1 and 2, hydrogen gas or nitrogen is contained in the slit material composed of an aggregate of beads filled inside the porous alumina support-CHA type zeolite membrane composite 1. Supply gas alone (indicated as single gas as supply gas composition), supply gas pressure in the slit material is 0.05 MPa (G), and permeate gas is released to atmospheric pressure, inside the slit material and outside the molecular sieve membrane The pressure permeance of each gas at 100 ° C. and the pressure loss before and after passing through the slit material at a supply gas flow rate (standard state: 0 ° C. converted to 0.1013 MPa) 100 or 200 mL / min is 0.05 MPa. It was measured. The results are shown in Table 5.

In the case of Examples 10 to 14 and Reference Example 3, hydrogen / nitrogen = 2 / in the slit material comprising an aggregate of beads filled inside the porous alumina support-CHA type zeolite membrane composite 1 1 gas mixture is supplied (as H ₂ / N ₂ = 2/1 gas mixture as supply gas composition), the pressure of the gas in the slit material is 0.05 MPa (G), and the permeated gas is released to atmospheric pressure. The differential pressure between the inside of the slit material and the outside of the molecular sieve membrane is set to 0.05 MPa, and the supply gas flow rate (standard state: converted to 0 ° C. 0.1013 MPa, expressed as the mixed gas flow rate) is 100 mL / min, 100 The permeance of each gas at ℃ and the pressure loss before and after passing through the slit material were evaluated. The results are shown in Table 6.

In the case of Examples 15 to 19 and Reference Example 4, hydrogen / nitrogen = 2 / in the slit material composed of the aggregate of beads filled inside the porous alumina support-CHA type zeolite membrane composite 2 1 gas mixture is supplied (as H ₂ / N ₂ = 2/1 gas mixture as supply gas composition), the pressure of the gas in the slit material is 0.05 MPa (G), and the permeated gas is released to atmospheric pressure. The differential pressure between the inside of the slit material and the outside of the molecular sieve membrane is 0.05 MPa, and the supply gas flow rate (standard state: converted to 0 ° C. 0.1013 MPa, expressed as the flow rate of the mixed gas) is 80 mL at 100 mL / min. The permeance of each gas at ℃ and the pressure loss before and after passing through the slit material were evaluated. The results are shown in Table 7.

  In addition, for comparison, the case where the filler was not filled (Comparative Examples 1 to 3) was similarly evaluated. Specifically, for Comparative Example 1, hydrogen gas or nitrogen gas was supplied alone, and for Comparative Examples 2 and 3, a hydrogen / nitrogen = 2/1 mixed gas was supplied for evaluation. The results are shown in Tables 5-7.

  In addition, since the fluctuation width of the pressure loss measuring device was observed to be about ± 0.3 kPa, it was described as 0 when the pressure loss measuring instrument showed a negative value.

  As the results of Tables 5 to 7 show, when glass beads are filled (Examples 1 to 19 and Reference Examples 1 to 4) and when beads are not filled (Comparative Examples 1 to 3) There was almost no difference in the permeance and permeance ratio between hydrogen and nitrogen (single gas permeance ratio is the ideal separation factor). This indicates that even when a slit material comprising an aggregate of fillers is used, the gas permeation / separation behavior of the molecular sieve membrane is not adversely affected.

  Further, as shown in the results of Table 5, when the gas flow rate is 200 mL / min (Examples 2, 4, 6, 8), the gas flow rate is 100 mL / min (Examples 1, 3, 5). 7), there was almost no difference in the permeance and permeance ratio between hydrogen and nitrogen (permeance ratio of single gas is the ideal separation factor). It shows that the gas flow rate does not adversely affect the gas permeation / separation behavior of the molecular sieve membrane.

  On the other hand, as shown by the results in Tables 5 to 7, it can be seen that the pressure loss before and after passing through the slit material depends on the average particle diameter of the beads, that is, the value of the longest gap diameter of the slit.

  For example, as in the results of Table 6, when beads having an average particle diameter of 600 μm or more are filled (Examples 13 and 14, Reference Example 3), the same as when beads are not filled (Comparative Example 2) It can be seen that no pressure loss occurs.

  Further, as shown in the results of Table 7, when a zeolite membrane composite having a higher gas permeability was used, when beads having an average particle diameter of 210 μm or more were filled (Examples 16 to 19, Reference Example 4). If it exists, it turns out that a pressure loss does not generate | occur | produce similarly to the case where a bead is not filled (comparative example 3).

  Further, as shown in the results of Table 5, it is understood that there is a difference in the magnitude of the generated pressure loss when beads having an average particle diameter of 80 μm or less and 210 μm or less are filled (Example 1, Reference Example 1). .

  Moreover, it turns out that a pressure loss will become large when supply gas flow velocity is doubled like the result of Table 5 (Examples 1-8). Similarly to the results in Table 6, it can be seen that there is a difference in the magnitude of the generated pressure loss when beads having an average particle diameter of 600 μm or more and beads having an average particle diameter of less than 600 μm are filled.

  As described above, it can be seen that, unlike the gas permeation / separation behavior of the molecular sieve membrane, the average particle diameter of the filler has an influence from the viewpoint of pressure loss. It is suggested that

  Combining the results of pressure loss and the results of the flame extinction test, in the mixed gas of hydrogen and air, hydrogen can be separated more efficiently if an aggregate of fillers with an average particle diameter of 80 μm or more and 1700 μm or less is used for the slit material. It is suggested that explosion can be prevented more appropriately. In addition, in a mixed gas of hydrogen and oxygen, if an aggregate of fillers having an average particle size of 80 μm or more and 600 μm or less is used as a slit material, hydrogen can be separated more efficiently and explosion can be prevented more appropriately. It is suggested that

  From the above, a molecular sieve membrane that separates hydrogen from a mixed gas, and a plurality of slits that are arranged in a space defined by the molecular sieve membrane or are arranged so as to cover the outside of the molecular sieve membrane. And using a hydrogen separator characterized by comprising an aggregate of fillers, hydrogen can be separated efficiently and explosion can be prevented. I understand that I can do it.

  The present invention can be used as a technique for safely separating hydrogen from a mixed gas containing hydrogen, for example, in a water splitting reaction process using a photocatalyst.

DESCRIPTION OF SYMBOLS 1 Introduction port 2 Collection | recovery port 3 Discharge port 10 Molecular sieve membrane 11 Outer wall material 12 Exterior body 20 Narrow gap material 30 Inorganic porous base material 50 Hydrogen separator

Claims (11)

  A molecular sieve membrane for separating hydrogen from the mixed gas, and a slit material having a plurality of slits arranged in a space defined by the molecular sieve membrane or covering the outside of the molecular sieve membrane And the slit material is made of an aggregate of fillers.   The hydrogen separator according to claim 1, wherein the slit of the slit material has a longest gap diameter of 1700 µm or less.   2. The hydrogen separator according to claim 1, wherein the slit of the slit material has a longest gap diameter of 600 [mu] m or less.   2. The hydrogen separator according to claim 1, wherein the slit of the slit material has a longest gap diameter of 310 [mu] m or less.   The hydrogen separator according to any one of claims 1 to 4, further comprising an inorganic porous substrate between the molecular sieve membrane and the slit material.   The hydrogen separator according to claim 5, wherein the inorganic porous substrate is alumina.   The hydrogen separator according to any one of claims 1 to 6, wherein the filler has an average particle size of 80 µm or more and 1700 µm or less.   The hydrogen separation apparatus according to any one of claims 1 to 7, wherein the molecular sieve membrane is any one of a zeolite membrane, a silica membrane, and a carbon membrane, or a combination thereof.   9. The hydrogen separator according to claim 8, wherein the skeleton of the crystalline zeolite forming the pores of the zeolite membrane is an oxygen 8-membered ring or less.   The hydrogen separation apparatus according to claim 8 or 9, wherein the zeolite membrane contains CHA-type zeolite.   A molecular sieve membrane for separating hydrogen from the mixed gas, and a slit material having a plurality of slits arranged in a space defined by the molecular sieve membrane or covering the outside of the molecular sieve membrane The slit material includes a first step of supplying a mixed gas to the slit material of a hydrogen separator comprising an aggregate of fillers, and hydrogen is separated from the mixed gas supplied in the first step. A hydrogen separation method comprising: a second step.