JP7413763B2 - Method for producing porous support-zeolite membrane composite - Google Patents

Description

The present invention relates to a method for producing a porous support-zeolite membrane composite, and more particularly, to a method for producing a porous support-zeolite membrane composite in which a dense AFX type zeolite membrane is formed on a porous support. . The porous support-zeolite membrane composite produced according to the present invention is suitably used to separate specific components from gaseous or liquid mixtures.

Zeolite membranes are attracting attention as a technology for separating desired gases from gases (gas mixtures) discharged from thermal power plants and various plants. Types of zeolite membranes include LTA type, FAU type, MFI type, SAPO-34, DDR type, and CHA type.

For example, zeolite membranes for separating carbon dioxide and methane used in natural gas purification plants and plants that generate biogas by methane fermentation of food waste include DDR zeolite (Patent Document 1), SAPO -34 (Non-Patent Document 1) and SSZ-13 (Non-Patent Document 2) are known.
Furthermore, in the separation of carbon dioxide and methane, it has been disclosed that a CHA-type aluminosilicate zeolite membrane with a SiO ₂ /Al ₂ O ₃ molar ratio of 5 or more has high permeability and high separation performance ( Patent Document 2).
A method of separating ammonia from a mixed gas of ammonia and nitrogen using a CHA type zeolite membrane is also disclosed (Patent Document 3).

However, the DDR type zeolite membrane cannot be said to have high carbon dioxide permeability because the zeolite structure is two-dimensional.
Additionally, although the CHA type zeolite membrane has a sufficiently large permeation amount of carbon dioxide, it cannot be said to have high nitrogen separation performance, perhaps because the pore diameter is 3.8 Å, which is larger than the kinetic diameter (3.64 Å) of nitrogen molecules. .

Patent Document 4 describes the following method with the objective of providing an AFX type zeolite membrane having a dense and uniform thickness.
"A method for producing a zeolite membrane composite, comprising:
a) obtaining a FAU type seed crystal;
b) depositing the FAU type seed crystal on a support;
c) immersing the support in a raw material solution and growing AFX type zeolite from the FAU type seed crystal by hydrothermal synthesis to form an AFX type zeolite membrane on the support;
d) removing the structure directing agent from the AFX type zeolite membrane;
A method for producing a zeolite membrane composite, comprising: ”

Paragraph 0008 of Patent Document 4 describes the problems of the prior art.
- When producing an AFX type zeolite membrane on the surface of a support, hydrothermal synthesis is performed by immersing the support in a raw material solution containing Y type zeolite powder, which is an aluminum source. Since the raw material solution tends to settle at the bottom of the container, it is difficult to suitably produce a zeolite membrane with a uniform thickness.
- If an AFX-type zeolite membrane is synthesized using a raw material solution that does not contain Y-type zeolite powder, the AFX-type zeolite tends to be insufficiently crystallized, making it difficult to form a dense AFX-type zeolite membrane. It becomes difficult. Therefore, especially when AFX type zeolite membranes are used for purposes such as gas separation, it may be difficult to improve the separation performance.
In the invention described in Patent Document 4, in order to solve the problems of the prior art, an FAU type seed crystal is attached to a support and the seed crystal is grown in a raw material solution that does not contain an Al element source. Performs hydrothermal synthesis.

Specifically, in Example 1 of Patent Document 4, after attaching a Y-type zeolite crystal as a seed crystal to a monolithic support, colloidal silica, sodium hydroxide, and SDA (structure directing agent) were added. 1,4-Diazabicyclo[2.2.2]octane-C4-diquatdibromide was dissolved in pure water and immersed in a raw material solution containing no Al element source, and hydrothermal synthesis was performed at 170°C for 50 hours. ing.

Note that paragraph 0042 of Patent Document 4 states, "Although the raw material solution does not need to contain an Al element source, it may be added as necessary." There is no example in which a seed crystal is specifically attached to a support and then an Al element source is added to a raw material solution. In addition, the same paragraph states, "At this time, by adjusting the blending ratio of the Si source and SDA in the raw material solution, a dense zeolite membrane 12 can be obtained." Patent Document In the invention described in 4, the conditions for making the film dense are the blending ratio of the Si source and SDA (structure directing agent), and the technical idea of making the film dense by the Al element source in the raw material solution is not exist.
Of course, the invention described in Patent Document 4 is based on the conventional technique of hydrothermal synthesis by immersing a support in a raw material solution containing Y-type zeolite powder, which is an aluminum source, but it is difficult to produce a zeolite membrane with a uniform thickness. This was done based on the knowledge that this was not possible, and it can be said that there are factors inhibiting the inclusion of an Al element source in the raw material solution.

Further, in Patent Document 4, there are no X-ray diffraction results of the produced AFX type zeolite membrane, and there is no mention of purity.

Japanese Patent Application Publication No. 2004-105942 Patent No. 5957828 JP 2014-58433 Publication JP 2019-150823 Publication

Shiguang Li et al., "Improved SAPO-34 Membranes for CO2/CH4 Separation". Adv. Mater. 2006,18,2601－2603 Halil Kalipcilar et al.,"Synthesis and Separation Performance of SSZ-13 Zeolite Membranes on Tubular Supports",Chem.Mater.2002,14,34583464

The present invention is a porous support-zeolite membrane composite in which a highly pure and dense AFX-type zeolite membrane is formed on a porous support, and is particularly suitable for the separation of small molecules such as nitrogen in gas mixtures. An object of the present invention is to provide a method for producing a porous support-zeolite membrane composite that can sufficiently obtain a separation effect due to molecular sieving action.

As a result of intensive studies by the present inventors in order to solve the above problems, in producing a porous support-zeolite membrane composite having an AFX type zeolite membrane, a porous support to which FAU type zeolite or CHA type zeolite was attached was found. It has been found that the above-mentioned problems can be solved by immersing the support in a raw material mixture containing an Al element source for hydrothermal synthesis, and the present invention has been achieved.

That is, the gist of the present invention is as follows.

[1] A method for producing a porous support-zeolite membrane composite having an AFX type zeolite membrane on a porous support, comprising the steps of attaching FAU type zeolite or CHA type zeolite to the surface of the porous support. , a step of immersing the porous support in a raw material mixture to perform hydrothermal synthesis, the raw material mixture containing an Al element source, a method for producing a porous support-zeolite membrane composite.

[2] The method for producing a porous support-zeolite membrane composite according to [1], wherein the FAU type zeolite or CHA type zeolite is in powder form.

[3] The method for producing a porous support-zeolite membrane composite according to [1], wherein the FAU type zeolite or CHA type zeolite is in the form of a membrane.

According to the present invention, it is possible to form a highly pure and dense AFX-type zeolite membrane on a porous support, and in particular, in the separation of gas mixtures, even when separating small molecules such as nitrogen, it is possible to use molecular sieving. It is possible to provide a porous support-zeolite membrane composite that can sufficiently obtain the separation effect of the zeolite membrane and perform efficient separation and concentration with sufficient throughput and separation performance.

FIG. 1 is a schematic diagram showing an example of the configuration of a separation membrane module to which the porous support-zeolite membrane composite of the present invention is applied. 3 is an XRD measurement chart of the zeolite membrane of the zeolite membrane composite manufactured in Comparative Example 1. 1 is an XRD measurement chart of the zeolite membrane of the zeolite membrane composite produced in Example 1. 3 is an XRD measurement chart of the zeolite membrane of the zeolite membrane composite manufactured in Example 2. 3 is an XRD measurement chart of the zeolite membrane of the zeolite membrane composite manufactured in Example 3. 3 is an XRD measurement chart of the zeolite membrane of the zeolite membrane composite produced in Example 4. 3 is an XRD measurement chart of the zeolite membrane of the zeolite membrane composite produced in Example 5. 2 is an XRD measurement chart of the zeolite membrane of the zeolite membrane composite manufactured in Example 6. 2 is an XRD measurement chart of the zeolite membrane of the zeolite membrane composite manufactured in Example 7. 3 is an XRD measurement chart of the zeolite membrane of the zeolite membrane composite manufactured in Comparative Example 2. 2 is an XRD measurement chart of the zeolite membrane of the zeolite membrane composite manufactured in Example 8. 12 is an XRD measurement chart of the zeolite membrane of the zeolite membrane composite produced in Example 9. 3 is an XRD measurement chart of the zeolite membrane of the zeolite membrane composite manufactured in Example 10. 3 is an XRD measurement chart of the zeolite membrane of the zeolite membrane composite produced in Example 11.

Hereinafter, the embodiments of the present invention will be described in more detail. However, the explanation of the constituent elements described below is an example of the embodiments of the present invention, and is not limited to the contents thereof. Various modifications can be made within the scope.

The method for producing the porous support-zeolite membrane composite (hereinafter sometimes simply referred to as "zeolite membrane composite") of the present invention includes:
A method for producing a porous support-zeolite membrane composite having an AFX type zeolite membrane on a porous support, the method comprising:
A step of attaching FAU type zeolite or CHA type zeolite to the surface of the porous support (hereinafter sometimes referred to as "first step"),
a step of hydrothermally synthesizing the porous support by immersing it in a raw material mixture (hereinafter sometimes referred to as the "second step"),
The raw material mixture is characterized in that it contains an Al element source.

In the following, the porous support-zeolite membrane composite produced by the method for producing a porous support-zeolite membrane composite of the present invention will be referred to as "the porous support-zeolite membrane composite of the present invention" or "the porous support-zeolite membrane composite of the present invention". zeolite membrane composite.
Further, the AFX type zeolite membrane is sometimes simply referred to as a "zeolite membrane."

[Porous support]
The porous support used in the present invention may be of any type as long as it has chemical stability such that zeolite can be crystallized in the form of a film on its surface and is porous.

Porous supports include gas-permeable porous materials such as polysulfone, cellulose acetate, aromatic polyamides, vinylidene fluoride, polyethersulfone, polyacrylonitrile, polyethylene, polypropylene, polytetrafluoroethylene, and polyimide. Molecules, ceramic sintered bodies such as silica, α-alumina, γ-alumina, mullite, zirconia, titania, yttria, silicon nitride, silicon carbide, metal sintered bodies such as iron, bronze, stainless steel, etc., and mesh shapes. Examples include inorganic porous supports such as molded bodies, glass, and carbon molded bodies.

Among these, inorganic porous supports containing sintered ceramics, which are solid materials whose basic components or most of them are composed of inorganic nonmetallic substances, are preferred. If such an inorganic porous support is used, a part thereof may be converted into zeolite during zeolite membrane synthesis, thereby achieving the effect of increasing the adhesion of the interface between the zeolite membrane and the porous support.

Examples of the ceramic sintered body include ceramic sintered bodies (ceramic supports) containing alumina such as silica, α-alumina, and γ-alumina, mullite, zirconia, titania, yttria, silicon nitride, and silicon carbide. . Among them, inorganic porous supports containing at least one of alumina, silica, and mullite are preferred. When these supports are used, it is easy to partially convert them into zeolites, which strengthens the bond between the porous support and the zeolite membrane, forming a dense porous support-zeolite membrane composite with high separation performance. It becomes easier.

The porous support used in the present invention preferably has an effect on its surface (hereinafter also referred to as "porous support surface") to crystallize the zeolite formed on the porous support.

It is preferable that the pore diameter of the porous support surface is controlled. The average pore diameter of the porous support near the surface of the porous support is usually 0.02 μm or more, preferably 0.05 μm or more, more preferably 0.1 μm or more, more preferably 0.15 μm or more, particularly preferably 0. .5 μm or more, particularly preferably 1 μm or more, and usually 20 μm or less, preferably 10 μm or less, more preferably 5 μm or less, particularly preferably 2 μm or less.

The surface of the porous support is preferably smooth, and if necessary, the surface may be polished with a file or the like.

The porosity of the porous support is usually 20% or more, preferably 25% or more, more preferably 30% or more, and usually 70% or less, preferably 60% or less, more preferably 50% or less. The porosity of a porous support influences the permeation flow rate when separating gases and liquids; below the above lower limit, it tends to inhibit the diffusion of permeate; when above the above upper limit, the strength of the porous support decreases. There is a tendency to decrease.

The shape of the porous support used in the present invention is not limited as long as it can effectively separate gas mixtures and liquid mixtures, and specifically, it can be flat, tubular, cylindrical, cylindrical, or square. Examples include honeycomb-like structures with many columnar holes and monoliths.

In the present invention, the surface of the porous support on which the zeolite is crystallized into a membrane may be any surface or may have multiple surfaces depending on the shape of the support. For example, in the case of a tubular porous support, it may be the outer surface or the inner surface, or in some cases both the outer and inner surfaces.

The average thickness (wall thickness) of the porous support is usually 0.1 mm or more, preferably 0.3 mm or more, more preferably 0.5 mm or more, and usually 7 mm or less, preferably 5 mm or less, more preferably 3 mm. It is as follows. The porous support is used to provide mechanical strength to the zeolite membrane, but if the average thickness of the porous support is too thin, the zeolite membrane composite will not have sufficient strength and will be susceptible to shock and vibration. It can become weak. If the average thickness of the porous support is too thick, the diffusion of the permeated substance may be poor, resulting in a low permeation flux.

For example, in the case of a tubular porous support, the length is usually 2 cm or more, preferably 4 cm or more, more preferably 8 cm or more, particularly preferably 10 cm or more, particularly preferably 20 cm or more, and usually 200 cm or less, preferably 150 cm or less, More preferably, it is 100 cm or less. If the length of the porous support is shorter than this range, the amount of fluid to be separated per piece may be small, and if it is longer than this range, manufacturing may be time consuming.
The inner diameter of the tubular porous support is usually 0.2 cm or more, preferably 0.3 cm or more, more preferably 0.4 cm or more, even more preferably 0.5 cm or more, particularly preferably 0.6 cm or more, and most preferably It is preferably 0.7 cm or more, even more preferably 0.9 cm or more, and usually 2 cm or less, preferably 1.5 cm or less, and more preferably 1.2 cm or less.
The outer diameter is usually 0.3 cm or more, preferably 0.5 cm or more, more preferably 0.6 cm or more, even more preferably 0.8 cm or more, particularly preferably 1.0 cm or more, and usually 2.5 cm or less, preferably It is 1.7 cm or less, more preferably 1.3 cm or less.
The thickness (thickness) is as described above.

If the inner diameter, outer diameter, and wall thickness are smaller than this range, the strength of the porous support may decrease and it may become easily broken. If the inner diameter and outer diameter are larger than this range, the number of porous supports that can be filled per unit volume may decrease. When the wall thickness is larger than this range, the transmission performance tends to decrease.

[AFX type zeolite]
The AFX type zeolite of the AFX type zeolite membrane formed in the present invention refers to the AFX type zeolite according to the code that defines the structure of zeolite established by the International Zeolite Association (IZA), and the structure is characterized by X-ray diffraction data. . In addition, AFX type zeolite, which contains d6r, gme, and aft, which are defined as a composite building unit by the International Zeolite Association (IZA) in its skeleton, has three-dimensional pores consisting of eight-membered oxygen rings, and is a type of AFX type zeolite. It is known that a certain material, SAPO-56, has a pore size of 3.4×3.6 Å.

As described below, the AFX type zeolite membrane in the present invention is produced by hydrothermally synthesizing a porous support to which FAU type zeolite or CHA type zeolite has been attached in advance in a raw material mixture containing an Al element source. It is formed.

[Zeolite membrane]
The zeolite membrane in the present invention refers to a membrane-like material composed of zeolite, and is preferably formed by crystallizing zeolite on the surface of the porous support. The zeolite constituting the membrane includes at least AFX type zeolite, and may optionally contain an inorganic binder such as silica or alumina, an organic substance such as a polymer, or a silylation agent for modifying the zeolite surface in addition to the zeolite.

The zeolite membrane formed on the porous support in the present invention is a membrane containing AFX type zeolite as the zeolite, preferably an AFX type zeolite membrane containing AFX type zeolite as a main component. The zeolite membrane may partially contain zeolites of other structures such as MOR type, MFI type, ANA type, and GIS type, and may also contain an amorphous component. The zeolite membrane is usually composed of AFX type zeolite in an amount of 70% by mass or more, preferably 80% by mass or more, and more preferably 90% by mass or more. The zeolite membrane is characterized in that in an X-ray diffraction pattern obtained by irradiating the surface of the zeolite membrane with X-rays, a peak attributed to AFX-type zeolite originates from AFX-type zeolite or another crystalline phase not attributed to the porous support. It is preferable that the peak be observed with high intensity. I ₁ is the peak intensity of the highest intensity peak among the peaks attributed to AFX type zeolite, and the highest intensity peak among the peaks derived from AFX type zeolite or other crystal phases not attributed to the porous support. When the intensity is _I2 , the peak intensity ratio _I2 / _I1 is usually 1.4 or less, preferably 1.0 or less, more preferably 0.5 or less, even more preferably 0.4 or less, particularly preferably It is 0.35 or less, particularly preferably 0.3 or less, most preferably 0.2 or less, and it is most preferable that only peaks attributed to the AFX type zeolite and the porous support are observed. This peak intensity ratio is for comparing the quantity ratio of impurities and AFX type zeolite, and the diffraction angles of both I ₁ and I ₂ can change depending on the manufacturing conditions.

The thickness of the zeolite membrane formed on the porous support in the present invention is not particularly limited, but is usually 0.1 μm or more, preferably 0.3 μm or more, more preferably 0.5 μm or more. , more preferably 0.7 μm or more, particularly preferably 1.0 μm or more, most preferably 1.2 μm or more. Further, it is usually 100 μm or less, preferably 80 μm or less, more preferably 60 μm or less, even more preferably 20 μm or less, particularly preferably 10 μm or less, and most preferably 5 μm or less. If the zeolite membrane is too thick, the amount of permeation tends to decrease, and if it is too thin, the selectivity or membrane strength tends to decrease.

The particle size of the zeolite in the zeolite membrane is not particularly limited, but if it is too small, the grain boundaries tend to become large and the permeation selectivity etc. tends to decrease, so it is usually 30 nm or more, preferably 50 nm or more, The thickness is more preferably 100 nm or more, further preferably 200 nm or more, particularly preferably 500 nm or more, and the upper limit is the thickness of the film or less. More preferably, the particle diameter of the zeolite is the same as the thickness of the zeolite membrane. This is because when the particle size of the zeolite is the same as the thickness of the zeolite membrane, the grain boundaries of the zeolite are the smallest. A zeolite membrane obtained by hydrothermal synthesis is preferable because the particle size of the zeolite and the thickness of the membrane may be the same in some cases.

The shape of the zeolite membrane (the shape when it is made into a zeolite membrane composite) is not particularly limited, and any shape such as a tubular shape, a hollow fiber shape, a monolith shape, a honeycomb shape, etc. can be adopted. Further, the size is not particularly limited, and for example, in the case of a tubular shape, it is usually practical and preferable to have a length of 2 cm or more and 200 cm or less, an inner diameter of 0.05 cm or more and 2 cm or less, and a thickness of 0.5 mm or more and 4 mm or less.

In the AFX type zeolite, the SiO ₂ /Al ₂ O ₃ molar ratio (hereinafter sometimes referred to as "SAR") of the zeolite is not particularly limited, but is usually 5 or more, preferably 6 or more, particularly preferably 8 or more. It is. The upper limit is usually the amount of impurities, and the SiO ₂ /Al ₂ O ₃ molar ratio is, for example, 500 or less, preferably 100 or less, more preferably 90 or less, even more preferably 80 or less, particularly preferably 65 or less, Most preferably it is 48 or less. If the SiO ₂ /Al ₂ O ₃ molar ratio is less than the above-mentioned lower limit, the zeolite membrane may become less dense and its durability tends to decrease. The SiO ₂ /Al ₂ O ₃ molar ratio can be adjusted by the reaction conditions of hydrothermal synthesis described later.

Note that the above-mentioned SiO ₂ /Al ₂ O ₃ molar ratio is a value obtained by scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDX). In order to obtain information on only a few micrometers of film, measurement is usually performed at an electron beam acceleration voltage of 10 kV.

[Method for manufacturing zeolite membrane]
In the present invention, the method for producing a zeolite membrane is not particularly limited as long as it is a method that can form a membrane containing AFX type zeolite on a porous support, for example,
(1) Method of crystallizing zeolite in a porous support in the form of a film (2) Method of fixing zeolite to a porous support with an inorganic binder or organic binder (3) Dispersing zeolite in a porous support Method for fixing the polymer (4) Any method can be used, such as a method in which the porous support is impregnated with a zeolite slurry and, in some cases, the zeolite is fixed to the porous support by suction.

Among these, a method in which zeolite is crystallized into a membrane on a porous support is particularly preferred. There are no particular limitations on the crystallization method, but the porous support may be placed in a reaction mixture for hydrothermal synthesis (hereinafter referred to as "aqueous reaction mixture" or "raw material mixture") used for zeolite production. Therefore, a method in which zeolite is crystallized on the surface of a support by direct hydrothermal synthesis is preferable.
Specifically, for example, an aqueous reaction mixture (raw material mixture) whose composition has been adjusted and homogenized is placed in a heat-resistant and pressure-resistant container such as an autoclave in which a porous support is loosely fixed, and the container is sealed. All you have to do is heat it for a certain period of time.

[Method for producing porous support-zeolite membrane composite]
The method for producing a porous support-zeolite membrane composite of the present invention includes a first step of attaching FAU type zeolite or CHA type zeolite to the surface of a porous support, and a porous support that has undergone the first step. A porous support-zeolite membrane composite having an AFX type zeolite membrane is manufactured through a second step of hydrothermal synthesis by immersion in a raw material mixture containing an Al element source.

Since AFX type zeolite contains an Al element source as an essential element, according to the present invention, a highly pure and dense AFX type zeolite membrane is formed by hydrothermal synthesis in a raw material mixture containing an Al element source. It is thought that it is possible to do so.

In addition, by attaching FAU type zeolite or CHA type zeolite to a porous support and hydrothermally synthesizing it in a raw material mixture containing an Al element source, we have developed a mechanism of action that allows formation of a highly pure and dense AFX type zeolite membrane. Although the details are not clear, it is inferred as follows.

That is, FAU type zeolite or CHA type zeolite contains in its skeleton some of the nanoparts contained in the skeleton of AFX type zeolite, and functions effectively as a seed crystal of AFX type zeolite. When such FAU type zeolite or CHA type zeolite adhered to the surface of a porous support is immersed in a raw material mixture containing an Al element source for hydrothermal synthesis, FAU on the porous support is Nanoparts produced from type zeolite or CHA type zeolite serve as nuclei and raw materials for crystal growth, and an AFX type zeolite membrane is formed on the porous support. At this time, in addition to AFX type zeolite crystals formed from FAU type zeolite or CHA type zeolite on the porous support, AFX type zeolite is also formed from the raw material mixture using the Al element source in the raw material mixture. Therefore, in addition to forming direct bonds between the nanoparts, bonds between the nanoparts are formed with the raw material derived from the raw material mixture having a composition suitable for forming AFX type zeolite. AFX-type zeolite is easily formed, and a sufficient amount of AFX-type zeolite can be grown to cover the entire surface of the porous support, and a highly pure and dense AFX-type zeolite membrane can be formed.

On the other hand, in the above-mentioned Patent Document 4, seed crystals of Y-type zeolite are attached to the support, but since the raw material solution does not contain an Al element source, the seed crystals are formed as nuclei and raw materials. Only zeolite constitutes the zeolite membrane, and since AFX type zeolite is not formed from the raw material solution side, it is difficult to form a highly pure and dense AFX type zeolite membrane.

In addition, in the present invention, "dense" means "few defects", and even if it is highly crystalline, there are gaps between crystal particles, especially AFX type zeolite, which has gaps between particles that are larger than the pore diameter. The main permeation path of the gas to be separated in the AFX type zeolite membrane is the gap, so that it is not possible to obtain a sufficient separation effect by the molecular sieving action in separating gas mixtures. This does not apply to "membrane".
On the other hand, even if the crystallinity is somewhat low, if the crystal grains are closely clustered together, the film falls under the category of "dense film."

<First step>
In the first step, FAU type zeolite or CHA type zeolite is attached to the surface of the porous support.

FAU type zeolite is a code that defines the structure of zeolite as determined by the International Zeolite Association (IZA), and is of FAU structure, preferably Y type or X type zeolite, with a low SiO ₂ /Al ₂ O ₃ ratio. Y-type zeolite is more preferable from the viewpoint of moderate dissolution in the raw material mixture. Among industrially produced FAU zeolites, those with a Si/Al molar ratio of less than about 2 are generally called X-type zeolites, and those with a Si/Al molar ratio of about 2 or more are called Y-type zeolites. FAU type zeolite contains d6r, which is a nanopart common to AFX type zeolite, in its skeleton. The FAU type zeolite may be one produced by hydrothermal synthesis, or a commercially available one may be used as it is.

The CHA type zeolite has a CHA structure, which is a code stipulating the structure of zeolite defined by the International Zeolite Association (IZA). CHA type zeolite contains d6r, which is a nanopart common to AFX type zeolite, in its skeleton. The CHA type zeolite may be one produced by hydrothermal synthesis, or a commercially available one may be used as is.

In the present invention, the SiO ₂ /Al ₂ O ₃ molar ratio of the FAU type zeolite or CHA type zeolite to be attached to the porous support is not particularly limited, but is usually 2 or more, preferably 3 or more, more preferably 5 or more, and Preferably it is 6 or more. The upper limit is usually the amount of Al element source equivalent to impurity, and the SiO ₂ /Al ₂ O ₃ molar ratio is, for example, 500 or less, preferably 200 or less, more preferably 100 or less, still more preferably 80, particularly preferably It is 40 or less, particularly preferably 30 or less, and most preferably 17 or less. If the SiO ₂ /Al ₂ O ₃ ratio is too low, it will be difficult to dissolve in the raw material mixture, and FAU-type zeolite or CHA-type zeolite may remain on the porous support, resulting in insufficient formation of AFX-type zeolite. It tends to be difficult to obtain a dense film. If the SiO ₂ /Al ₂ O ₃ molar ratio is too high, it will be easily dissolved in the raw material mixture and AFX type zeolite will be easily formed, but it will be difficult to remain on the porous support during the AFX type zeolite membrane formation process. Therefore, AFX type zeolite tends to be difficult to form as a dense film.

In the present invention, the method for controlling the SiO ₂ /Al ₂ O ₃ molar ratio of the FAU type zeolite or CHA type zeolite to be attached to the porous support is not particularly limited, and the SiO ₂ /Al ₂ ratio when the zeolite is formed is not particularly limited. The O ₃ molar ratio may be used as it is, or the SiO ₂ /Al ₂ O ₃ molar ratio may be adjusted by performing Al removal treatment such as steam treatment after the zeolite is formed. In the case where the SiO ₂ /Al ₂ O ₃ molar ratio is adjusted by post-synthesis Al removal treatment, the Al element has been eliminated from the zeolite skeleton, so the SiO ₂ /Al ₂ O ₃ molar ratio is adjusted from the beginning. It is easier to dissolve in the raw material mixture than the formed one. Therefore, it is better to use the SiO ₂ /Al ₂ O ₃ molar ratio as it was when the zeolite was formed, without adjusting the SiO ₂ /Al ₂ O ₃ molar ratio by post-treatment etc., because AFX type zeolite can be used as a dense membrane. It is preferable because it is easy to form.

In the present invention, the FAU type zeolite or the CHA type zeolite attached to the porous support may contain an organic template (structure directing agent) or a metal cation as a countercation.
Specifically, it may contain an organic template (structure directing agent) used as necessary in crystallizing zeolite, the organic template may be removed by heat treatment or extraction, or the original You may use one that does not contain an organic template, but one that contains an organic template is more difficult to dissolve in the raw material mixture and produces nanoparts that become the core of AFX type zeolite crystals and the raw material. Although it becomes difficult to form a zeolite membrane, it tends to remain on the porous support during the AFX-type zeolite membrane formation process and tends to form a dense membrane, which is preferable.

In addition, for example, metal cations used to suitably form the crystal structure of zeolite may be included, or the metal cations may be removed or replaced with other metal cations by ion exchange treatment or the like. Those that do not originally contain metal cations may also be used. If metal cations are included, they tend to be difficult to dissolve in the raw material mixture, making it difficult to generate the core of AFX type zeolite crystals and the nanoparts that serve as raw materials. It is preferable because it tends to remain on the body and form a dense film.

In the present invention, only either FAU type zeolite or CHA type zeolite may be attached to the porous support, or both may be attached.
Among these, it is preferable to use at least FAU zeolite because FAU zeolite has a lower skeleton density than AFX-type zeolite and is therefore more likely to be reconstituted into AFX zeolite with a higher skeleton density.

The FAU type zeolite or CHA type zeolite attached to the porous support may be in the form of a powder or a film.

When the FAU type zeolite or the CHA type zeolite is in powder form, the particle size is not particularly limited, but from the viewpoint of adhering seed crystals on the porous support, it is desirable that the particle size is close to the pore size of the support. The average primary particle diameter is usually 0.5 nm or more, preferably 1 nm or more, more preferably 2 nm or more, and usually 20 μm or less, preferably 15 μm or less, more preferably 10 μm or less, even more preferably 5 μm or less, particularly preferably It is 1 μm or less, particularly preferably 500 nm or less. Note that the average primary particle diameter in the present invention corresponds to the particle diameter of primary particles. The average primary particle size is determined by measuring the particle size of 30 or more arbitrarily selected particles by observing the particles using a scanning electron microscope (SEM), and averaging the particle size of the primary particles. In this case, the particle diameter is the diameter of a circle having an area equal to the projected area of the particle (circle equivalent diameter).
If the average primary particle diameter is less than the above lower limit, it will be too small compared to the pore diameter of the porous support, making it difficult to attach a sufficient amount to the surface of the porous support, and the seeds may even get inside the porous support. Gas permeation tends to be inhibited by the adhesion of crystals and the formation of AFX type zeolite. If the average primary particle size is larger than the above upper limit, it is too large relative to the pore size of the porous support and is likely to be detached after attachment, which may be a cause of defects in the zeolite membrane.

The method for attaching FAU type or CHA type zeolite powder onto the porous support is not particularly limited. For example, zeolite powder is dispersed in a solvent such as water, and the porous support is immersed in the dispersion to coat the surface. This can be achieved by the dipping method in which seed crystals are attached, or by dispersing zeolite powder in a solvent such as water, immersing a porous support with one end sealed in the dispersion, and then sucking the porous support from the other end. A suction method in which zeolite powder is firmly attached to the surface of a porous support, a method in which zeolite powder is mixed with a solvent such as water to form a slurry, and a slurry is applied onto the porous support can be used.

In order to control the amount of zeolite powder deposited on the porous support and to produce a porous support-zeolite membrane composite with good reproducibility, the dipping method and the suction method are desirable. The solvent in which the zeolite powder is dispersed is not particularly limited, but water is preferred.

The amount of zeolite powder to be dispersed is not particularly limited, and is usually 0.01% by mass or more, preferably 0.1% by mass or more, and more preferably 0.5% by mass or more, based on the total mass of the dispersion. Further, it is usually 40% by mass or less, preferably 20% by mass or less, more preferably 10% by mass or less, still more preferably 5% by mass or less, particularly preferably 3% by mass or less.
If the amount of zeolite powder to be dispersed is too small, the amount of zeolite powder adhering to the porous support will be small, resulting in areas where zeolite is not generated partially on the surface of the porous support during hydrothermal synthesis, and defects may occur. There is a possibility that it will become a certain film. The amount of zeolite powder that adheres to the porous support by the dipping method becomes almost constant as long as the amount of zeolite powder in the dispersion exceeds a certain level, so if the amount of zeolite powder in the dispersion is too large, There is a lot of waste, which is disadvantageous in terms of cost.

When attaching a membrane-like FAU-type zeolite or CHA-type zeolite to a porous support, FAU-type or CHA-type zeolite crystals are grown in a membrane-like form on the porous support. What is necessary is to form a film.
In this case, there is no particular restriction on the thickness of the FAU type zeolite membrane or the CHA type zeolite membrane on the porous support, as long as it satisfies the following amount of zeolite deposited.

The amount of FAU type zeolite or CHA type zeolite deposited on the porous support in advance is not particularly limited, and is usually 0.01 g or more, preferably 0.03 g in mass per 1 m ² of surface area of the porous support. As mentioned above, it is more preferably 0.05 g or more, still more preferably 0.1 g or more, and usually 200 g or less, preferably 100 g or less, more preferably 50 g or less, still more preferably 40 g or less.
When the amount of FAU type zeolite or CHA type zeolite deposited is less than the above lower limit, crystals are difficult to form, and film growth tends to be insufficient or non-uniform. In addition, if the amount of powdered FAU zeolite or CHA zeolite deposited exceeds the above upper limit, the surface irregularities may be increased by the FAU zeolite or CHA zeolite, or the FAU zeolite may have fallen from the porous support. Alternatively, CHA type zeolite may facilitate the growth of spontaneous nuclei, thereby inhibiting film growth on the porous support. In either case, it tends to be difficult to form a dense AFX type zeolite membrane. If the amount of film-like FAU zeolite or CHA zeolite attached exceeds the above upper limit, the FAU zeolite or CHA zeolite may remain after hydrothermal synthesis. In either case, it tends to be difficult to form a dense AFX type zeolite membrane.

In addition, powdered FAU type zeolite or CHA type zeolite and membrane-shaped FAU type zeolite or CHA type zeolite may be attached to a porous support. Alternatively, a method of attaching FAU type zeolite or CHA type zeolite powder to a CHA type zeolite membrane by the above-mentioned dipping method, or a method of attaching FAU type zeolite or CHA type zeolite powder to a FAU type zeolite or CHA type zeolite membrane Methods such as rubbing can be adopted. In this case as well, it is preferable that the total amount of deposited film-like material and powdery material is within the above range.

<Second process>
In the second step, the porous support to which FAU type zeolite or CHA type zeolite was attached in the first step is immersed in a raw material mixture containing an Al element source to perform hydrothermal synthesis. AFX type zeolite is synthesized thereon to form an AFX type zeolite membrane.

<Raw material mixture (aqueous reaction mixture)>
The raw material mixture (aqueous reaction mixture) used in the second step contains an Al element source as an essential component, but preferably contains a Si element source and optionally an organic template, an alkali source, and water.

Examples of Si element sources used in the aqueous reaction mixture (raw material mixture) include amorphous silica, colloidal silica, silica gel, sodium silicate, amorphous aluminosilicate gel, tetraethoxysilane (TEOS), trimethylethoxysilane, and water glass. etc. can be used.

The Al element source used in the raw material mixture (aqueous reaction mixture) is not particularly limited, and includes, for example, sodium aluminate, aluminum hydroxide, aluminum sulfate, aluminum nitrate, aluminum oxide, amorphous aluminosilicate gel, Y-type A solid aluminosilicate containing zeolite such as the like can be used. From the viewpoint that it is composed only of elements that are the main components of zeolite, and that the produced AFX type zeolite membrane is difficult to contain impurity components, it is recommended to use sodium aluminate, aluminum hydroxide, aluminum oxide, amorphous aluminosilicate gel, Y type, etc. Solid aluminosilicate containing zeolite is more preferred, and sodium aluminate and amorphous aluminosilicate are even more preferred since a uniform raw material mixture (aqueous reaction mixture) can be easily obtained, and sodium aluminate is particularly preferred.

The Si element source and the Al element source are used so that the SiO ₂ /Al ₂ O 3 molar ratio in the obtained AFX type zeolite falls within the above-mentioned preferred range, but the Al element source is used such that the Al ₂ O ₃ /SiO ₂ molar ratio The above-mentioned raw material mixture contains 0.0001 or more, especially 0.001 or more, especially 0.01 or more in the raw material mixture (aqueous reaction mixture, not including seed crystals described below). This is preferable in order to reliably obtain the effect of the Al element source in the liquid (aqueous reaction mixture). However, even if the amount of Al element source in the raw material mixture (aqueous reaction mixture) is excessively large, the raw material mixture (aqueous reaction mixture) may gelatinize or zeolites other than AFX type zeolite may be easily formed. Therefore, the Al element source content in the raw material mixture (aqueous reaction mixture, not including seed crystals described below) is 0.5 or less, particularly 0.1 or less, as an Al ₂ O ₃ /SiO ₂ molar ratio. In particular, it is preferably 0.05 or less.

Note that in addition to the Al element source and the Si element source, other element sources such as Ga, Fe, B, Ti, Zr, Sn, and Zn may be used.

In the crystallization of AFX type zeolite, an organic template (structure directing agent) can be used if necessary, and one synthesized using an organic template is more preferable. By synthesizing using an organic template, the ratio of silicon atoms to aluminum atoms in crystallized AFX type zeolite increases, and the amount of alkali cations in the pores that exist as charge compensation for aluminum atoms decreases. Diffusion inhibition is less likely to occur, and permeability (permeation performance) is improved.

The organic template may be of any type as long as it can form the desired AFX type zeolite membrane. Further, one type of organic template or a combination of two or more types may be used.

In the synthesis of AFX type zeolite according to the present invention, amines are usually used as organic templates. Preferably it is a quaternary ammonium ion, and specifically, for example, a nitrogen-containing six-membered ring compound such as 1,4-diazabicyclo[2.2.2]octane or quinuclidine, or an amine such as triethylamine is used to Examples include dimer structures obtained by crosslinking. Examples of the structure of the crosslinked portion include a saturated hydrocarbon chain, and the number of carbon atoms thereof is preferably 4 or 5. Further, nitrogen-containing five-membered ring compounds can also be used, such as pyrrolidine derivatives having two pyrrolidyl groups and structures having substituents on two nitrogen atoms of imidazole. This substituent is not particularly limited, but preferably has a cyclic structure such as a bulky hydrocarbon group or an adamantyl group.

Such organic template cations are accompanied by anions that do not harm the formation of AFX-type zeolites. Representative examples of such anions include halogen ions such as Cl ^- , Br ^- and I ^- , hydroxide ions, acetates, sulfates, and carboxylates. Among these, hydroxide ions are particularly preferably used.

When using an organic template, the amount of organic template to be used is determined based on the silicon (Si) contained in the raw material mixture (aqueous reaction mixture, not including seed crystals described below) from the viewpoint of ease of crystal formation. The molar ratio is usually 0.01 or more, preferably 0.05 or more, more preferably 0.1 or more, and usually 1 or less, preferably 0.5 or less, more preferably 0.3 or less. If the amount of organic template used is less than the above lower limit, AFX type zeolite may not be sufficiently produced. If the amount of organic template used is greater than the above upper limit, the cost will rise, which is disadvantageous.

Examples of alkali sources include hydroxide ions as counter anions of organic templates, alkali cations contained in Si element sources and Al element sources, alkali metal hydroxides such as NaOH and KOH, and alkaline earth metals such as Ca(OH) ₂ . Metal hydroxides and the like can be used.

The type of alkali is not particularly limited, and two or more types may be used in combination. Usually, Na, K, Li, Rb, Cs, Ca, Mg, Sr, Ba, etc. are used. Among these, Na is more preferred.

By using an appropriate amount of the alkali source, it becomes easier to coordinate the organic template to silicon or aluminum in a suitable state, thereby making it easier to form a crystal structure. The molar ratio R/Si between the metal element (R) of the alkali source and the silicon (Si) contained in the raw material mixture (aqueous reaction mixture, not including seed crystals described below) is usually 0.1 or more, Preferably 0.2 or more, more preferably 0.25 or more, even more preferably 0.3 or more, particularly preferably 0.35 or more, and usually 2.0 or less, preferably 1.5 or less, more preferably 1 It is .0 or less, more preferably 0.8 or less.

If the molar ratio of the alkali metal element to silicon (R/Si) is larger than the above upper limit, the generated AFX type zeolite will be easily dissolved, and the AFX type zeolite may not be obtained or the yield may be significantly low. be. If R/Si is smaller than the above lower limit, the raw material Si element source and Al element source will not be sufficiently dissolved, a uniform raw material mixture (aqueous reaction mixture) will not be obtained, and AFX type zeolite will be difficult to produce. It may happen.

The amount of water in the raw material mixture (aqueous reaction mixture) is determined based on the amount of silicon (Si) contained in the raw material mixture (aqueous reaction mixture, not including seed crystals described below) from the viewpoint of ease of crystal formation. The molar ratio is usually 3 or more, preferably 5 or more, more preferably 8 or more, still more preferably 10 or more. In addition, from the viewpoint of cost reduction for waste liquid treatment, the amount is usually 100 mol or less, preferably 50 mol or less.

In the present invention, since FAU type zeolite or CHA type zeolite is attached to the porous support in advance, it is not necessary to have seed crystals in the raw material mixture during hydrothermal synthesis. By adding crystals, crystallization of AFX type zeolite can be promoted.

Any type of seed crystal can be used as long as it is a zeolite that promotes crystallization, but in order to achieve efficient crystallization, it is preferable that the structure of the nanoparts that form the skeleton is the same as that of AFX type zeolite. . Specifically, those containing d6r, gme, or aft in the skeleton, which are defined as composite building units by the International Zeolite Association (IZA), are preferred because they are easily reconstituted into AFX type zeolites.

Zeolite structures containing d6r in the skeleton are AEI, AFT, AFV, AFX, AVL, CHA, EAB, EMT, ERI, FAU, GME, JSR, KFI, LEV, LTL, LTN, MOZ, MSO, MWW, OFF, SAS. , SAT, SAV, SBS, SBTSFW, SSF, SWY, SZR, TSC, WEN, and SVY. Zeolite structures containing gme in the skeleton include AFX, EAB, EON, GME, LTF, MAZ, OFF, SFW, and SWY. Examples of zeolite structures containing aft in the skeleton include AFT and AFX. Among these, AFX, CHA, and FAU are more preferred. Among these, FAU is particularly preferable because it has a lower skeleton density than AFX and is therefore more likely to be rearranged into AFX having a higher skeleton density.

The particle size of the seed crystal is not particularly limited. The particle size of the seed crystal is usually 0.5 nm or more, preferably 1 nm or more, more preferably 2 nm or more, and usually 20 μm or less, preferably 15 μm or less, more preferably 10 μm or less, as observed by SEM. The thickness is more preferably 5 μm or less, particularly preferably 1 μm or less, particularly preferably 500 nm or less. By using seed crystals with small particle size as seed crystals added to the raw material mixture (aqueous reaction mixture), the seed crystals do not settle in the raw material mixture (aqueous reaction mixture) and are dispersed more uniformly, resulting in more efficiency. It can promote crystallization of AFX type zeolite well.

When containing seed crystals in the raw material mixture (aqueous reaction mixture), the amount of seed crystals to be contained in the raw material mixture (aqueous reaction mixture) is not particularly limited, and the amount of seed crystals contained in the raw material mixture (aqueous reaction mixture) is not limited to the total mass of the raw material mixture (aqueous reaction mixture). On the other hand, it is usually 0.001% by mass or more, preferably 0.01% by mass or more, and more preferably 0.1% by mass or more. Further, it is usually 50% by mass or less, preferably 40% by mass or less, more preferably 30% by mass or less, still more preferably 20% by mass or less, particularly preferably 10% by mass or less.
If the amount of seed crystals dispersed in the raw material mixture (aqueous reaction mixture) is too small, the effect of promoting zeolite crystallization cannot be obtained sufficiently by using seed crystals, and if the amount is too large, the amount added may be too small. No commensurate effect can be obtained, and a lot of seed crystals are wasted, which is disadvantageous in terms of cost.

<Method of fixing porous support>
During hydrothermal synthesis, there is no particular restriction on the method of fixing the porous support immersed in the raw material mixture (aqueous reaction mixture), and it can be placed in any manner such as vertically or horizontally. An AFX type zeolite membrane may be formed on the fixed porous support by a static method, or an AFX type zeolite membrane may be formed while stirring the raw material mixture (aqueous reaction mixture).

<Hydrothermal synthesis reaction conditions>
The heating temperature during hydrothermal synthesis to form an AFX type zeolite membrane is not particularly limited, but is usually 100°C or higher, preferably 120°C or higher, more preferably 140°C or higher, and usually 200°C or lower, preferably 190°C or lower. The temperature is more preferably 180°C or lower, more preferably 160°C or lower, particularly preferably 150°C or lower. If the reaction temperature is too low, the zeolite may be difficult to crystallize. Furthermore, if the reaction temperature is too high, a type of zeolite different from the AFX type zeolite in the present invention may be easily produced, or a film may be formed that is not dense (with defects).

The reaction time for hydrothermal synthesis is not particularly limited, but for example, when the heating temperature is 150°C, it is usually 1 hour or more, preferably 5 hours or more, more preferably 10 hours or more, particularly preferably 20 hours or more, particularly preferably is 40 hours or more, usually 15 days or less, preferably 10 days or less, more preferably 8 days or less, even more preferably 6 days or less, particularly preferably 70 hours or less. If the reaction time of hydrothermal synthesis is too short, the zeolite may crystallize and become difficult to synthesize. In addition, in hydrothermal synthesis, FAU type zeolite or CHA type zeolite attached to a porous support is converted to AFX type zeolite, but if the reaction time of this hydrothermal synthesis is too short, There is a possibility that some FAU type zeolite or CHA type zeolite may remain. If the reaction time of hydrothermal synthesis is too long, a type of zeolite different from the AFX type zeolite in the present invention may be easily produced. The reaction time can vary depending on the heating temperature. Lowering the heating temperature increases the reaction time.

The pressure during the hydrothermal synthesis reaction is not particularly limited, and the autogenous pressure generated when the raw material mixture (aqueous reaction mixture) placed in a closed container is heated to this temperature range is sufficient. Furthermore, if necessary, an inert gas such as nitrogen may be added.

<Heat treatment>
The zeolite membrane composite obtained by hydrothermal synthesis is washed with water and then heat-treated. Here, heat treatment means applying heat to dry the zeolite membrane composite, or firing the organic template when an organic template is used.

The temperature of the heat treatment is usually 50°C or higher, preferably 80°C or higher, more preferably 100°C or higher, and usually 200°C or lower, preferably 150°C or lower when the purpose is drying. The temperature increase rate and temperature decrease rate during the heat treatment for drying may be the same as in the case of removing the organic template described below.

The heating time is not particularly limited as long as the AFX type zeolite membrane on the porous support is sufficiently dried, and is preferably 0.5 hours or more, more preferably 1 hour or more. The upper limit is not particularly limited, and is usually within 200 hours, preferably within 150 hours, and more preferably within 100 hours.

[Air permeation amount of porous support-zeolite membrane composite]
A zeolite membrane that has been subjected to heat treatment for the sole purpose of drying is referred to as an as-made zeolite membrane. The air permeation amount [L/(m ²・h)] of the zeolite membrane composite of the present invention in as-made is usually 245 L/(m ²・h) or less, preferably 100 L/(m ²・h) or less. , more preferably 50 L/(m ² ·h) or less, still more preferably 30 L/(m ² ·h) or less. Since the as-made zeolite membrane has organic templates in its pores, air mainly passes through the gaps between the zeolite particles. Therefore, a large amount of air permeation through an as-made zeolite membrane indicates that the zeolite membrane has many defects and low density, and the lower the amount of air permeation through an as-made zeolite membrane, the better.

Here, the amount of air permeation is the amount of air permeation [L/(m ² h) when the zeolite membrane composite is connected to a vacuum line with an absolute pressure of 5 kPa, as will be explained in detail in the Examples section below. ].

<Removal of organic template>
When hydrothermal synthesis is performed in the presence of an organic template, the organic template can be removed by, for example, heat treatment or extraction, preferably heat treatment, i.e., calcination, after washing the resulting zeolite membrane composite with water. Appropriate.

The firing temperature in this case is usually 350°C or higher, preferably 400°C or higher, more preferably 430°C or higher, even more preferably 480°C or higher, and usually 900°C or lower, preferably 850°C or lower, and even more preferably 800°C. The temperature below is particularly preferably 750°C or below. If the calcination temperature is too low, the proportion of organic templates remaining tends to increase, and the pores of AFX type zeolite are small, which may reduce the permeation flux during separation and concentration. If the calcination temperature is too high, the difference in thermal expansion coefficient between the porous support and AFX type zeolite will increase, which may cause cracks to occur in the AFX type zeolite membrane, causing the AFX type zeolite membrane to lose its compactness and cause separation. Performance may decrease.

The firing time varies depending on the temperature increase rate and temperature decrease rate, but is not particularly limited as long as the organic template is sufficiently removed, and is preferably 1 hour or more, more preferably 5 hours or more. The upper limit is not particularly limited, and is usually within 200 hours, preferably within 150 hours, more preferably within 100 hours, and most preferably within 24 hours.
Firing may be performed in an air atmosphere, but may also be performed in an atmosphere to which oxygen is added.

It is desirable that the temperature increase rate during firing be as slow as possible in order to reduce the occurrence of cracks in the AFX type zeolite membrane due to the difference in thermal expansion coefficient between the porous support and the AFX type zeolite. The temperature increase rate is usually 5°C/min or less, preferably 2°C/min or less, more preferably 1°C/min or less, particularly preferably 0.5°C/min or less. Usually, the speed is 0.1° C./min or more in consideration of workability.
Furthermore, the rate of temperature decrease after firing must be controlled to avoid cracks in the AFX type zeolite membrane. As with the heating rate, the slower the temperature the better. The temperature decreasing rate is usually 5°C/min or less, preferably 2°C/min or less, more preferably 1°C/min or less, particularly preferably 0.5°C/min or less. Usually, the speed is 0.1° C./min or more in consideration of workability.

<Ion exchange of AFX type zeolite membrane>
The AFX type zeolite membrane formed on the porous support may be ion-exchanged if necessary. In the case of synthesis using an organic template, ion exchange is usually performed after removing the organic template.

Ions to be ion-exchanged include protons, alkali metal ions such as Na ⁺ , K ⁺ , and Li ⁺ , alkaline earth metal ions such as Ca ²⁺ , Mg ²⁺ , Sr ²⁺ , and Ba ²⁺ , and transitions such as Fe, Cu, and Zn. Examples include metal ions. Among these, protons and alkali metal ions such as Na ⁺ , K ⁺ and Li ⁺ are preferred.

Ion exchange is usually performed by removing the AFX type zeolite membrane after calcination (such as when an organic template is used) with an ammonium salt such as NH ₄ NO ₃ or NaNO ₃ or an aqueous solution containing the ions to be exchanged, or in some cases an acid such as hydrochloric acid. This may be carried out by a method such as processing at a temperature from room temperature to 100° C. and then washing with water. Furthermore, it may be fired at 200 to 500°C if necessary.

[Air permeation amount of porous support-zeolite membrane composite]
The air permeation amount [L/(m ² · h)] of the zeolite membrane composite of the present invention (the zeolite membrane composite after heat treatment (heat treatment here refers to removal of organic template by calcination)) is usually 2700 L/(m ²・h) or less, preferably 1400 L/(m ²・h) or less, more preferably 1000 L/(m ²・h) or less, even more preferably 700 L/(m ²・h) or less, even more Preferably 600 L/(m ²・h) or less, particularly preferably 500 L/(m ²・h) or less, particularly preferably 300 L/(m ²・h) or less, most preferably 200 L/(m ²・h) or less It is. The lower limit of air permeation is not particularly limited, but is usually 0.01 L/(m ²・h) or more, preferably 0.1 L/(m ²・h) or more, more preferably 1 L/(m ²・h) or more. It is.

Here, the amount of air permeation is the amount of air permeation [L/(m ² h) when the zeolite membrane composite is connected to a vacuum line with an absolute pressure of 5 kPa, as will be explained in detail in the Examples section below. ].

The zeolite membrane composite of the present invention has excellent properties as described above, and can be suitably used as a membrane separation means for separating specific components from a gas mixture or a liquid mixture.

[Amount of zeolite attached to zeolite membrane composite]
The amount of zeolite attached to the zeolite membrane composite of the present invention is usually 1 g or more, preferably 1 g or more in terms of mass per 1 m ² of surface area, including the FAU type zeolite or CHA type zeolite attached to the porous support before hydrothermal synthesis. is 5 g or more, more preferably 10 g or more, still more preferably 20 g or more, and usually 2000 g or less, preferably 1000 g or less, more preferably 500 g or less, still more preferably 300 g or less.
If the amount of zeolite attached is less than the above lower limit, the selectivity and zeolite membrane strength will tend to decrease in the separation and concentration operations described below, and if it exceeds the above upper limit, the amount of permeation will decrease. There is a tendency to

[Separation method of gas mixture or liquid mixture]
By bringing a gas mixture or a liquid mixture into contact with the porous support-zeolite membrane composite of the present invention and allowing the highly permeable components to permeate, the components can be separated. Hereinafter, this separation method may be referred to as "the method for separating gas mixtures or liquid mixtures of the present invention".
According to the method for separating a gas mixture or liquid mixture of the present invention, components with low permeability can be concentrated by allowing components with high permeability to pass through.

In the method for separating a gas mixture or liquid mixture of the present invention, a gas mixture or liquid mixture consisting of a plurality of components is brought into contact with one side of the porous support side or the zeolite membrane side via the zeolite membrane composite of the present invention, By applying a lower pressure on the opposite side than the side in contact with the gas mixture or liquid mixture, components with high permeability to the zeolite membrane (substances in the mixture with relatively high permeability) are removed from the gas or liquid mixture. ) is selectively transmitted, that is, as the main component of the permeable substance. This makes it possible to separate highly permeable substances from gaseous or liquid mixtures. As a result, by increasing the concentration of a specific component (substance in the mixture with relatively low permeability) in the gas mixture or liquid mixture, the specific component can be separated, recovered, or concentrated.

The gas mixture to be separated or concentrated is not particularly limited as long as it can be separated or concentrated by the porous support-zeolite membrane composite of the present invention.
Examples of gas mixtures include carbon dioxide, oxygen, nitrogen, methane, ethane, ethylene, propane, propylene, normal butane, isobutane, 1-butene, 2-butene, isobutene, sulfur hexafluoride, helium, carbon monoxide, Examples include those containing at least one component selected from nitrogen monoxide, water, and the like. Among these gas components, gas components with high permeance are separated by passing through the zeolite membrane composite, and gas components with low permeance are concentrated on the supply gas side.

The gas mixture contains at least two of the above components. In this case, the two types of components are preferably a combination of a component with high permeance and a component with low permeance.
Here, permeance (also referred to as "permeability") is the amount of permeating substance divided by the product of the membrane area, time, and partial pressure difference between the supply side and the permeate side of the permeating substance, and the unit is , [mol·(m ² ·s·Pa) ⁻¹ ].

Specifically, gas mixtures include gas mixtures containing carbon dioxide and nitrogen, gas mixtures containing carbon dioxide and methane, gas mixtures containing hydrogen and hydrocarbons, gas mixtures containing hydrogen and oxygen, and hydrogen and dioxide. These include gas mixtures containing carbon, gas mixtures containing nitrogen and oxygen, gas mixtures containing methane and helium, and include air, natural gas, combustion gases and coke oven gas, and land file gases generated from landfills. It can also be used for the separation or concentration of biogas such as methane, steam reformed gas of methane produced and discharged in the petrochemical industry, etc.

Among these, the present invention is particularly suitable for separating and concentrating gas mixtures containing carbon dioxide and nitrogen, gas mixtures containing nitrogen and oxygen, and gas mixtures containing hydrogen and oxygen.

The liquid mixture to be separated or concentrated by the zeolite membrane composite of the present invention is not particularly limited as long as it is a liquid mixture that can be separated or concentrated by the zeolite membrane composite of the present invention.

The liquid mixture includes a liquid mixture of water and an organic compound.
Examples of organic compounds include carboxylic acids such as acetic acid, acrylic acid, propionic acid, formic acid, lactic acid, oxalic acid, tartaric acid, and benzoic acid, sulfonic acid, sulfinic acid, habituric acid, uric acid, phenol, enol, and diketone type compounds. , thiophenols, imides, oximes, aromatic sulfonamides, and organic acids such as primary and secondary nitro compounds; alcohols such as methanol, ethanol, isopropanol (2-propanol); ketones such as acetone, methyl isobutyl ketone, etc. aldehydes such as acetaldehyde; ethers such as dioxane and tetrahydrofuran; organic compounds containing nitrogen (N-containing organic compounds) such as amides such as dimethylformamide and N-methylpyrrolidone; esters such as acetic acid ester and acrylic acid ester Examples include.

Among these, organic compounds containing at least one selected from alcohols, ethers, ketones, aldehydes, and amides are particularly desirable. Among these organic compounds, those having 2 to 10 carbon atoms are preferred, and those having 3 to 8 carbon atoms are more preferred.

Further, the organic compound may be a polymer compound that can form a mixture (mixed solution) with water. Examples of such polymer compounds include those having a polar group in the molecule, such as polyols such as polyethylene glycol and polyvinyl alcohol; polyamines; polysulfonic acids; polycarboxylic acids such as polyacrylic acid; Carboxylic acid esters; Modified polymer compounds obtained by modifying polymers by graft polymerization, etc.; Copolymerized polymer compounds obtained by copolymerizing a nonpolar monomer such as an olefin with a polar monomer having a polar group such as a carboxyl group. Examples include the following.

Furthermore, the water-containing organic compound may be a mixture of water and a polymer emulsion. Here, the polymer emulsion is a mixture of a surfactant and a polymer that is commonly used in adhesives, paints, and the like. Examples of polymers used in the polymer emulsion include polyvinyl acetate, polyvinyl alcohol, acrylic resins, polyolefins, olefin-polar monomer copolymers such as ethylene-vinyl alcohol copolymers, polystyrene, polyvinyl ether, polyamide, polyester, and cellulose. Thermoplastic resins such as derivatives; thermosetting resins such as urea resins, phenolic resins, epoxy resins, and polyurethanes; rubbers such as natural rubber, polyisoprene, polychloroprene, butadiene copolymers such as styrene-butadiene copolymers, etc. Can be mentioned. Furthermore, as the surfactant, any known surfactant may be used.

More specifically, the liquid mixture includes organic acids/water, alcohols/water, ketones such as acetone and methyl isobutyl ketone/water, aldehydes/water, ethers such as dioxane and tetrahydrofuran/water, and dimethylformamide. , nitrogen-containing organic compounds (nitrogen-containing organic substances) such as amides such as N-methylpyrrolidone/water, esters such as acetic acid ester/water, etc. According to the zeolite membrane composite of the present invention, these organic compounds Organic compounds can be separated and concentrated by selectively permeating water from a mixed aqueous solution of compounds and water.

Conditions for separating and concentrating these gas mixtures and liquid mixtures may be those known per se, depending on the target gas species, liquid species, composition, etc.

The shapes of separation membrane modules equipped with zeolite membrane composites used for separating gas mixtures or liquid mixtures include flat membrane types, spiral types, hollow fiber types, cylindrical types, honeycomb types, etc., depending on the application. The most suitable form is selected.

One of these, a cylindrical separation membrane module, will be explained with reference to FIG.

In FIG. 1, a cylindrical tube-shaped zeolite membrane composite 1 is placed in a thermostatic chamber (not shown) while being housed in a pressure-resistant container 2 made of stainless steel. The constant temperature bath is equipped with a temperature control device so that the temperature of the sample mixture can be adjusted.

One end of the zeolite membrane composite 1 is sealed with a cylindrical end pin 3. The other end is connected by a connecting portion 4, and the other end of the connecting portion 4 is connected to the pressure container 2. The inside of the zeolite membrane composite 1 and a pipe 11 for discharging the permeated component 8 are connected via a connecting part 4 , and the pipe 11 extends from the pressure vessel 2 .
A pipe 12 for supplying a sweep fluid 9 such as a sweep gas is inserted into the zeolite membrane composite 1 via a pipe 11 .
A pressure gauge 5 that measures the pressure on the supply side of the sample mixture and a back pressure valve 6 that adjusts the pressure on the supply side are connected to any point communicating with the pressure vessel 2.
Each connection part is airtightly connected.

The sample mixture 7 is supplied at a constant flow rate between the pressure vessel 2 and the zeolite membrane composite 1, and the pressure on the supply side is kept constant by the back pressure valve 6. The permeated component 8 permeates through the zeolite membrane composite 1 according to the partial pressure difference between the inside and outside of the zeolite membrane composite 1, and is discharged through the pipe 11 to obtain an impermeable component (concentrated component) 10.

The separation of gaseous or liquid mixtures is usually carried out within the range of 0 to 500°C. In view of the separation characteristics of the zeolite membrane composite of the present invention, the separation temperature is preferably within the range of room temperature to 200°C.

When the porous support-zeolite membrane composite of the present invention is used for separating or concentrating a gas mixture or liquid mixture, it is preferable to perform a pretreatment prior to the separation and concentration operation.

Pretreatment of the porous support-zeolite membrane composite includes the following pretreatment operations.
(1) The porous support-zeolite membrane composite is dried for about 0 to 10 hours at a temperature higher than the operating temperature during separation and concentration of a gas mixture or liquid mixture, for example, at a temperature 0 to 250° C. higher.
(2) Purging the porous support-zeolite membrane composite with components that permeate through separation and concentration of the gas or liquid mixture. Specifically, at the above drying temperature, a gas smaller than the pore diameter of the AFX type zeolite is supplied under pressure to the outside of the membrane.

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to examples, but the present invention is not limited to the description of the following examples unless it exceeds the gist thereof.

(1) X-ray diffraction (XRD)
XRD measurement was performed based on the following conditions.
・Device name: X'PertPro MPD manufactured by PANalytical in the Netherlands
・Optical system specifications Incidence side: Enclosed X-ray tube (CuKα)
Soller Slit (0.04rad)
Divergence Slit (Variable Slit)
Sample stage: XYZ stage
Light receiving side: Semiconductor array detector (X' Celerator)
Ni-filter
Soller Slit (0.04rad)
Goniometer radius: 240mm
・Measurement conditions X-ray output (CuKα): 45kV, 40mA
Scan axis: θ/2θ
Scanning range (2θ): 5.0-70.0°
Measurement mode: Continuous
Reading width: 0.05°
Counting time: 99.7sec
Automatic variable slit (Automatic-DS): 1mm (irradiation width)
Lateral divergence mask: 10mm (irradiation width)

Note that the X-rays were irradiated in a direction perpendicular to the axial direction of the cylindrical tube (zeolite membrane composite). In addition, in order to avoid noise as much as possible, X-rays are transmitted at one of the two lines where the cylindrical-tubular zeolite membrane composite placed on the sample stand and a plane parallel to the sample stand surface are in contact with the sample stand surface. Instead, it mainly hit the other line above the sample stage surface.
In addition, measurements were made with the irradiation width fixed at 1 mm using an automatic variable slit. An XRD pattern was obtained by performing variable slit → fixed slit conversion using XRD analysis software JADE 7.5.2 (Japanese version).

(2) Air permeation amount Under atmospheric pressure, one end of the zeolite membrane composite is sealed, and the other end is connected to a 5 kPa vacuum line while maintaining airtightness. The flow rate of air that permeated through the zeolite membrane composite was measured with a mass flow meter installed between the two, and was defined as the air permeation amount [L/(m ² ·h)]. As a mass flow meter, 8300 manufactured by KOFLOC, for N ₂ gas, with a maximum flow rate of 500 ml/min (20° C., converted to 1 atmosphere) was used. If the mass flow meter reading for KOFLOC 8300 is 10 ml/min (20°C, 1 atm) or less, use Lintec's MM-2100M, for Air gas, maximum flow rate 20 ml/min (0°C, 1 atm) Measured using

(3) Gas permeation/separation test A single-component gas permeation test and a multiple-component gas separation test were conducted as follows using a separation membrane module schematically shown in FIG. The sample gases used were carbon dioxide (purity 99.9%, manufactured by Kosatsu Gas Kogyo Co., Ltd.), methane (purity 99.999%, manufactured by Japan Fine Products Co., Ltd.), and nitrogen (industrial nitrogen gas, manufactured by Toho Sanso Kogyo Co., Ltd.). , or hydrogen (purity 99.99% or higher, generated from a hydrogen generator OPGU-2200 manufactured by HORIBA STEC).

The configuration of this separation membrane module is as described above.
In this separation membrane module, a sample gas (supply gas 7) was supplied between the pressure vessel 2 and the zeolite membrane composite 1 at a constant flow rate, and the pressure on the supply side was kept constant by the back pressure valve 6. On the other hand, the permeated gas 8 that passed through the zeolite membrane composite 1 was measured with a flow meter (not shown) connected to the pipe 11. In addition, the non-permeable gas 10 was measured with a flow meter (not shown) connected to the pipe 12. Furthermore, in the case of the gas separation test, the gases of permeated gas 8 and non-permeated gas 10 were fractionated and subjected to component analysis using a gas chromatograph.

More specifically, in order to remove components such as moisture and air, after drying at a temperature higher than the measurement temperature and purging with exhaust or the supply gas used, the temperature of the sample and the supply gas of the zeolite membrane composite 1 are reduced. After the differential pressure between the 7 side and the permeated gas 8 side is kept constant and the permeated gas flow rate is stabilized, the flow rate of the sample gas (permeated gas 8) that has permeated through the zeolite membrane composite 1 is measured, and the gas permeance [mol・(m ² ·s·Pa) ⁻¹ ] was calculated. For the pressure when calculating permeance, the pressure difference (differential pressure) between the supply side and the permeation side of the supply gas was used. In the case of a gas separation test, the permeance [mol・(m ²・s・Pa) ⁻¹ ] was calculated.
In the gas permeation test, the permeance ratio α was calculated using the following formula (1) based on the above measurement results. For example, the permeance ratio of hydrogen and nitrogen is calculated as follows.
α=P _H2 /P _N2 (1)
[In formula (1), P _H2 and P _N2 represent hydrogen and nitrogen permeance [mol·(m ² ·s·Pa) ⁻¹ ], respectively]
The same applies to other gas types.
Also in the gas separation test, the permeance ratio α was calculated using the following formula (2) based on the above measurement results. For example, the permeance ratio of hydrogen and nitrogen is calculated as follows.
α=p _H2 /p _N2 (2)
[In formula (2), p _H2 and p _N2 are the permeance [mol・(m ²・s・Pa) ⁻¹ ] of the sample gas that permeated the zeolite membrane composite 1 as a mixed gas of hydrogen and nitrogen, respectively. Among them, each permeance of hydrogen and nitrogen [mol・(m ²・s・Pa) ⁻¹ ] is shown]
The same applies to other gas types.

[Comparative example 1]
<Synthesis of zeolite for adhesion>
AFX type zeolite for adhesion was synthesized as follows.
1.24 g of NaOH (manufactured by Kishida Chemical Co., Ltd.), 1.87 g of water, and 10.8 g of 1,4-Bis (DABCO) Butanediminium DiHydroxide (hereinafter sometimes abbreviated as DABCO. Manufactured by Seichem Co., Ltd. 19.8 mass % aqueous solution) was added and stirred to dissolve NaOH. Thereto, 3.81 g of FAU type zeolite (SAR=30, Zeolyst CBV720) was added and stirred at room temperature for 2 hours to prepare a raw material mixture for hydrothermal synthesis. The composition of the obtained raw material mixture for hydrothermal synthesis was 1SiO ₂ /0.033Al ₂ O ₃ /0.50NaOH/0.10DABCO/10H ₂ O (molar ratio).

This raw material mixture for hydrothermal synthesis was placed in a pressure-resistant container and left in an oven at 150° C. to perform hydrothermal synthesis for 72 hours. After the hydrothermal synthesis reaction, the reaction solution was cooled and the produced crystals were collected by filtration. After drying the collected crystals at 100° C. for 12 hours, the XRD of the obtained zeolite powder was measured, and it was confirmed that it was AFX type zeolite. When the obtained AFX type zeolite was observed by SEM, the particle size was about 1 μm.

<Attachment of zeolite to porous support>
As a porous support, an alumina tube (outer diameter 12 mm, inner diameter 9 mm, manufactured by Noritake Company Limited) was cut into a length of 40 mm, washed with water, and then dried.

Crystals of AFX type zeolite synthesized for adhesion and having a particle diameter of about 1 μm were dispersed in water to prepare a 1% by mass AFX type zeolite dispersion. The porous support is immersed in the prepared AFX type zeolite dispersion with a stopper at the bottom end and a tube attached from the top end, and the inside of the porous support is vacuumed through the tube and maintained for 3 seconds. Then, AFX type zeolite was attached to the porous support. The porous support to which the AFX type zeolite was attached was dried at 120° C. for 30 minutes. The amount of AFX type zeolite attached was 17 g/m ² .

<Hydrothermal synthesis>
1.38g of FAU type zeolite (NaY, SAR=5, manufactured by JGC Catalysts & Chemicals Co., Ltd.), 0.382g of NaOH (manufactured by Kishida Chemical Co., Ltd.), and 59.5g of water were mixed and stirred, and 15.37g of Water glass No. 3 (manufactured by Kishida Chemical Co., Ltd.) and 13.95 g of a DABCO 19.8% by mass aqueous solution (manufactured by Seichem Co., Ltd.) were added and stirred at room temperature for 2 hours to prepare a raw material mixture for hydrothermal synthesis. The composition of the obtained raw material mixture for hydrothermal synthesis was 1SiO ₂ /0.033Al ₂ O ₃ /0.70NaOH/0.10DABCO/50H ₂ O (molar ratio).

The porous support to which AFX type zeolite was attached was immersed vertically into a Teflon (registered trademark) inner cylinder containing a raw material mixture for hydrothermal synthesis, the autoclave was sealed, and the autoclave was heated at 150°C for 72 hours under autogenous pressure. It was heated under. After a predetermined period of time had elapsed, the porous support-zeolite membrane composite was left to cool, taken out from the autoclave, washed, and dried at a temperature of 100° C. or higher and 120° C. or lower for 1 hour or more. After drying and before firing the template (hereinafter sometimes referred to as as-made), one end of the cylindrical tube is sealed and the other end is connected to a vacuum line to reduce the pressure inside the tube, and a flowmeter with a vacuum line installed. When the amount of air permeation was measured under the above-mentioned conditions, the amount of permeation was 0.0 L/(m ² ·h).

<Removal of template>
In order to remove the template of the obtained zeolite membrane composite, it was fired in an electric furnace at 500°C for 5 hours (template firing step) to obtain a fired zeolite membrane composite. At this time, the heating rate and cooling rate to 150°C are both 2.5°C/min, the heating rate and cooling rate from 150°C to 450°C are 0.5°C/min, and the heating rate from 450°C to 500°C. The temperature rate and cooling rate were 0.1°C/min.

<Measurement/Evaluation>
Based on the difference between the weight of the zeolite membrane composite after firing and the weight of the porous support, the weight of the zeolite crystallized on the porous support was 30 g/m ² . The air permeation amount of the zeolite membrane composite after firing was 600 L/(m ² ·h). When the produced membrane was subjected to XRD measurement, it was found that AFX-type zeolite was produced, but many ANA-type zeolites were also produced as by-products, and the peak with the highest intensity (2θ = 22 .0 [deg]) is I ₁ , and the highest intensity peak (2θ = 16.2 [deg]) of the peaks derived from AFX type zeolite or other crystalline phases not assigned to the porous support. When the peak intensity was defined as I ₂ , the peak intensity ratio I ₂ /I ₁ was 1.45.
An XRD measurement chart is shown in FIG.
In Comparative Example 1, the raw material mixture contains an Al element source, but since AFX type zeolite rather than FAU type zeolite or CHA type zeolite was attached to the porous support, the AFX type zeolite used as a seed crystal was added to the raw material mixture. By being heated in the liquid for a long time, a portion of the zeolite was converted to ANA type zeolite, and although it was dense, an AFX type zeolite membrane with high purity could not be obtained.

Note that in FIG. 2 and FIGS. 3 to 14 described later, the peak indicated by the "S" mark in the figure is attributed to the porous support. Moreover, the peak indicated by the "*" mark in the figure is a peak of an impurity crystalline substance that is not assigned to the AFX type zeolite or the porous support.

[Example 1]
<Attachment of zeolite to porous support>
FAU type zeolite prepared in the same manner as the seed crystal described in Example 1 of International Publication No. 2015/159986 was dispersed in 2% by mass water and used as the FAU type zeolite dispersion for adhesion. FAU type zeolite was deposited on the porous support using a similar operation. The amount of FAU type zeolite deposited was 39 g/m ² .

<Hydrothermal synthesis>
As a raw material mixture for hydrothermal synthesis, 0.78 g of aluminum hydroxide (containing 53.5% by mass of Al ₂ O ₃ , manufactured by Aldrich Co., Ltd.), 9.74 g of a 1 mol/l NaOH aqueous solution (manufactured by Kishida Chemical Co., Ltd.), and water. While mixing and stirring 17.36 g, 31.0 g of Water Glass No. 3 (manufactured by Kishida Chemical Co., Ltd.) and 25.75 g of DABCO (19.8% by mass aqueous solution, manufactured by Seichem) were added, and the mixture was stirred at room temperature for 2 hours. A porous support-zeolite membrane composite was produced in the same manner as in Comparative Example 1, except that the synthesis time was 144 hours. The composition of the raw material mixture for hydrothermal synthesis used was 1SiO ₂ /0.033Al ₂ O ₃ /0.70NaOH/0.10DABCO/25H ₂ O (molar ratio).

<Measurement/Evaluation>
The air permeation rate of the as-made zeolite membrane composite thus obtained was 0 L/(m ² ·h), suggesting that a dense membrane was obtained. The weight of the zeolite crystallized on the porous support, determined from the difference between the weight of the zeolite membrane composite after firing and the weight of the porous support, was 180 g/m ² . The air permeation amount of the zeolite membrane composite after firing was 320 L/(m ² ·h).
When the produced membrane was subjected to XRD measurement, it was confirmed that AFX type zeolite was produced. ANA type zeolite is also a by-product, and the peak intensity of the highest peak (2θ = 21.9 [deg]) among the peaks attributed to AFX type zeolite is I ₁ , AFX type zeolite or porous support. When the peak intensity of the highest intensity peak (2θ = 26.2 [deg]) among the peaks derived from other crystal phases not assigned to is I ₂ , the peak intensity ratio I ₂ /I ₁ is 1.24 Met. Even though it was heated for a long time compared to Comparative Example 1, the intensity of the peak derived from the ANA type zeolite was reduced compared to the peak derived from the AFX type zeolite. It can be seen that the formation of AFX type zeolite was promoted by hydrothermal synthesis using a support in a raw material mixture containing an Al element source.
An XRD measurement chart is shown in FIG.

Using this zeolite membrane composite, a single component gas permeation test was conducted at a test temperature of 140°C, a supply gas pressure of 0.4 MPa, and a permeate gas pressure of atmospheric pressure, and the CO ₂ permeance (P _CO2 ) was 5. 14×10 ⁻⁷ [mol・(m ²・s・Pa) ⁻¹ ], _CH4 gas permeance P _CH4 is 7.09×10 ⁻⁸ [mol・(m ²・s・Pa) ⁻¹ ], The permeance ratio P _CO2 /P _CH4 was 7.3. Since CH ₄ molecules are larger than the pore diameter of AFX type zeolite, they are expected to all diffuse through the zeolite grain boundaries rather than through the zeolite pores and pass through the membrane. Assuming that the diffusion of CO ₂ and CH ₄ at the grain boundaries in the zeolite film is Knudsen diffusion, the permeance ratio P _CO2 /P _CH4 at the defect can be calculated as 0.603 from the following equation.
P _CO2 /P _CH4 = (MW _CH4 ×T) ^0.5 / (MW _CO2 ×T) ^0.5
(MW _CO2 and MW _CH4 are the molecular weights of _CO2 and _CH4 , respectively, T is the test temperature [K])
Since the permeance ratio P _CO2 /P _CH4 in the entire zeolite membrane was larger than the permeance ratio P _CO2 /P _CH4 in Knudsen diffusion, it was found that CO ₂ selectively permeated through the zeolite pores. Therefore, it was suggested that this zeolite membrane has CO ₂ /CH ₄ separation ability derived from the molecular sieve of AFX type zeolite pores.

In this example, hydrothermal synthesis was performed in a raw material mixture containing an Al element source using a porous support to which FAU type zeolite was attached, so that AFX type zeolite had relatively high purity and was as-made. A dense AFX-type zeolite membrane with a low air permeation rate could be formed on a porous support, and a zeolite membrane composite with a high separation effect due to molecular sieving action could be obtained.

[Example 2]
<Attachment of zeolite to porous support>
A 10% by mass dispersion of FAU type zeolite (SAR=30, CBV720 manufactured by Zeolyst) was ball milled for 6 hours using 3φ Al ₂ O ₃ balls (using 3 times the amount of the dispersion), and the dispersion was diluted to 2% by mass with water. FAU zeolite was adhered to a porous support in the same manner as in Comparative Example 1, except that the FAU zeolite dispersion prepared above was used instead of the AFX zeolite dispersion. The amount of FAU type zeolite deposited was 20 g/m ² .

<Hydrothermal synthesis>
Using this FAU type zeolite-adhered porous support, a porous support-zeolite membrane composite was produced in the same manner as in Example 1, except that the reaction time was 72 hours.

<Measurement/Evaluation>
The weight of the as-made zeolite crystallized on the porous support, determined from the difference between the weight of the as-made zeolite membrane composite thus obtained and the weight of the porous support, is 160 g/m It was ² . When the produced membrane was subjected to XRD measurement, it was confirmed that AFX type zeolite was produced.
The peak intensity of the highest peak (2θ = 22.1 [deg]) among the peaks attributed to AFX type zeolite is I ₁ , which is derived from AFX type zeolite or other crystalline phases not attributed to the porous support. When the peak intensity of the highest intensity peak (2θ=22.9[deg]) is _I2 , the peak intensity ratio _I2 / _I1 is 0.31, indicating that the AFX type has relatively high purity. It was suggested that a zeolite film was formed.
An XRD measurement chart is shown in FIG.

In this example as well, hydrothermal synthesis was performed in a raw material mixture containing an Al element source using a porous support to which FAU type zeolite was attached, so that an AFX type zeolite membrane with high purity AFX type zeolite was made into a porous structure. could be formed on a support.

[Example 3]
<Attachment of zeolite to porous support>
A porous support-FAU type zeolite (Y type zeolite) membrane composite was produced by direct hydrothermal synthesis on the porous support.
As a porous support, an alumina tube (outer diameter 12 mm, inner diameter 9 mm, manufactured by Noritake Company Limited) was cut into a length of 40 mm, washed with water, and then dried.
FAU type zeolite (NaY, SAR=5, manufactured by JGC Catalysts & Chemicals Co., Ltd., hereinafter sometimes referred to as "NaY5") was used as a seed crystal for FAU type zeolite membrane synthesis. A 3% by mass aqueous dispersion of NaY5 was prepared, a porous support was dried at 120°C for 30 minutes or more, the top and bottom of which were sealed with silicone rubber plugs, and then immersed in this seed crystal dispersion to attach seed crystals. After removing the seed crystals from the dispersion, the seed crystals were attached to the support by rubbing with fingers wearing latex gloves (hereinafter sometimes referred to as the rubbing method). Thereafter, it was dried at 100° C. for 1 hour or more to obtain a porous support with seed crystals attached. The amount of attached seed crystals was 1.7 g/m ² .

After dissolving 4.48 g of NaOH (manufactured by Kishida Chemical Co., Ltd.) in 50 g of water, a sodium aluminate aqueous solution (Na ₂ O 18.9 mass %, Al ₂ O ₃ 20.13 mass % manufactured by Asada Chemical Industry Co., Ltd.)3. 0 g was added and stirred, and a pre-mixed mixture of 12.4 g of Water Glass No. 3 (manufactured by Kishida Chemical Co., Ltd.) and 31.26 g of water was added thereto, and the mixture was stirred at room temperature for 12 hours to obtain a raw material mixture for hydrothermal synthesis. was prepared. The composition of the obtained raw material mixture for hydrothermal synthesis was 1SiO ₂ /0.1Al ₂ O ₃ /2.8NaOH/84H ₂ O (molar ratio).

The seed crystal-attached porous support was vertically immersed in a Teflon (registered trademark) inner tube containing a raw material mixture for hydrothermal synthesis, the autoclave was sealed, and the autoclave was heated at 100° C. for 5 hours under autogenous pressure. After a predetermined period of time, the porous support-zeolite membrane composite was left to cool, taken out from the autoclave, washed, and dried at 100° C. for over 1 hour to obtain a porous support-FAU type zeolite membrane composite. The weight of the FAU type zeolite crystallized on the porous support was 37 g/m ² as determined from the difference in weight between the obtained zeolite membrane composite and the porous support.

<Hydrothermal synthesis>
A zeolite membrane composite was obtained in the same manner as in Example 2, except that the above-mentioned alumina support-FAU type zeolite membrane composite was used instead of the porous support to which FAU type zeolite was attached.

<Measurement/Evaluation>
The air permeation rate of the as-made zeolite membrane composite thus obtained was 35 L/(m ² ·h), suggesting that a dense membrane was obtained. The weight of the zeolite crystallized on the porous support, determined from the difference between the weight of the zeolite membrane composite after firing and the weight of the porous support, was 270 g/m ² . The air permeation amount of the zeolite membrane composite after firing was 190 L/(m ² ·h). When the produced membrane was subjected to XRD measurement, AFX-type zeolite was produced, and ANA-type zeolite was also produced as a by-product, and among the peaks attributed to AFX-type zeolite, the highest intensity peak (2θ = 21.9 [deg] ) is the peak intensity of I ₁ , and the peak intensity of the highest peak (2θ = 26.2 [deg]) among the peaks derived from AFX type zeolite or other crystalline phases not assigned to the porous support is I ₂ When the peak intensity ratio I ₂ /I ₁ was 1.38, it was suggested that an AFX type zeolite membrane with relatively high purity was formed.
An XRD measurement chart is shown in FIG.

Using this zeolite membrane composite, a single component gas permeation test was conducted at a test temperature of 50°C, a supply gas pressure of 0.4 MPa, and a permeate gas pressure of atmospheric pressure, and the CO ₂ permeance (P _CO2 ) was 2. 13×10 ⁻⁷ [mol・(m ²・s・Pa) ⁻¹ ], CH ₄ gas permeance P _CH4 is 4.97×10 ⁻⁸ [mol・(m ²・s・Pa) ⁻¹ ], The permeance ratio P _CO2 /P _CH4 was 4.3. Since CH ₄ molecules are larger than the pore diameter of AFX type zeolite, they are expected to all diffuse through the zeolite grain boundaries rather than through the zeolite pores and pass through the membrane. Assuming that the diffusion of CO ₂ and CH ₄ at the grain boundaries in the zeolite film is Knudsen diffusion, the permeance ratio P _CO2 /P _CH4 at the defect can be calculated as 0.603 from the following equation.
P _CO2 /P _CH4 = (MW _CH4 ×T) ^0.5 / (MW _CO2 ×T) ^0.5
(MW _CO2 and MW _CH4 are the molecular weights of _CO2 and _CH4 , respectively, T is the test temperature [K])
Since the permeance ratio P _CO2 /P _CH4 in the entire zeolite membrane was larger than the permeance ratio P _CO2 /P _CH4 in Knudsen diffusion, it was found that CO ₂ selectively permeated through the zeolite pores. Therefore, it was suggested that this zeolite membrane has CO ₂ /CH ₄ separation ability derived from the molecular sieve of AFX type zeolite pores.

In this example as well, hydrothermal synthesis was performed in a raw material mixture containing an Al element source using a porous support to which FAU type zeolite was attached, resulting in relatively high purity and a low air permeation amount in as-made. It was possible to form a dense AFX type zeolite membrane with a low density on a porous support, and to obtain a zeolite membrane composite with a high separation effect due to molecular sieving action.

[Example 4]
<Attachment of zeolite to porous support>
A 2% by mass dispersion of FAU zeolite was prepared using FAU zeolite synthesized in the same manner as in Example 1, except that the reaction time during synthesis of FAU zeolite for adhesion was changed to 3 days. The FAU zeolite was attached to the porous support by suction for 2 seconds, and then the FAU zeolite was attached to the porous support by rubbing with fingers wearing latex gloves. Thereafter, it was dried at 120° C. for 30 minutes or more to obtain a FAU type zeolite-adhered porous support. The amount of FAU type zeolite attached was 6.6 g/m ² .

<Hydrothermal synthesis>
Using the obtained FAU type zeolite-attached porous support, a zeolite membrane composite was obtained in the same manner as in Example 2, except that the reaction temperature was 140°C.

<Measurement/Evaluation>
The air permeation rate of the as-made zeolite membrane composite thus obtained was 0 L/(m ² ·h), suggesting that a dense membrane was obtained. The weight of the zeolite crystallized on the porous support, determined from the difference between the weight of the zeolite membrane composite after firing and the weight of the porous support, was 84 g/m ² . The air permeation amount of the zeolite membrane composite after firing was 200 L/(m ² ·h). When the produced membrane was subjected to XRD measurement, it was confirmed that AFX type zeolite was produced. Almost no peaks derived from AFX type zeolite or other crystal phases not assigned to the porous support were observed, suggesting the formation of an extremely pure AFX type zeolite membrane. The peak intensity of the highest peak (2θ = 26.2 [deg]) among the peaks attributed to AFX type zeolite is I ₁ , which is derived from AFX type zeolite or other crystalline phases not attributed to the porous support. When the peak intensity of the peak with the highest intensity among the peaks (2θ=23.1 [deg]) was defined as I ₂ , the peak intensity ratio I ₂ /I ₁ was 0.39.
An XRD measurement chart is shown in FIG.

Using this zeolite membrane composite, a single component gas permeation test was conducted at a test temperature of 140°C, a supply gas pressure of 0.4 MPa, and a permeate gas pressure of atmospheric pressure, and the _CO2 permeance _PCO2 was 8.99× 10 ^-7 [mol・(m ²・s・Pa) ⁻¹ ], CH ₄ gas permeance P _CH4 is 8.28×10 ⁻⁸ [mol・(m ²・s・Pa) ⁻¹ ], permeance ratio P _CO2 /P _CH4 was 10.9. Since the permeance ratio P _CO2 /P _CH4 in the entire zeolite membrane was larger than the permeance ratio P _CO2 /P _CH4 in Knudsen diffusion, it was found that CO ₂ selectively permeated through the zeolite pores. Therefore, it was suggested that this zeolite membrane has CO ₂ /CH ₄ separation ability derived from the molecular sieve of AFX type zeolite pores.

In this example as well, the AFX type zeolite has a very high purity because it was hydrothermally synthesized in a raw material mixture containing an Al element source using a porous support to which the FAU type zeolite was attached, and it is as-made. A dense AFX-type zeolite membrane with a low air permeation rate could be formed on a porous support, and a zeolite membrane composite with a high separation effect due to molecular sieving action could be obtained.

[Example 5]
<Attachment of zeolite to porous support>
In the same manner as Example 5 of Japanese Patent No. 5585126 (however, the composition of the raw material mixture for hydrothermal synthesis was 1SiO ₂ /0.066Al ₂ O ₃ /0.15NaOH/0.1KOH/0.04TMADAOH/100H). ₂ O (molar ratio)) prepared alumina porous support-CHA type zeolite membrane composite (alumina porous support: outer diameter 12 mm, inner diameter 9 mm, manufactured by Noritake Company Limited) was cut into 40 mm pieces. Furthermore, FAU type zeolite was attached as follows.
As the FAU type zeolite dispersion for adhesion, proton type FAU type zeolite (SAR=10, HST-35OHVA manufactured by Tosoh Corporation, hereinafter sometimes referred to as "HY10") is bead milled in the coexistence of water, and the dispersion is made up to D ₅₀ = 150 μm. A pulverized 20% by mass dispersion was used.
A porous support-CHA type zeolite membrane composite was immersed in a 20% by mass dispersion of bead-milled HY10, then rubbed, in the same manner as in Example 4, except that the immersion and suction time was 20 seconds. It was similarly dried and FAU type zeolite was attached.

<Hydrothermal synthesis>
As mentioned above, the alumina porous support-CHA type zeolite membrane composite to which FAU type zeolite was attached was immersed in the raw material mixture for hydrothermal synthesis, and hydrothermal synthesis was performed in the same manner as in Example 2. I got it.

<Measurement/Evaluation>
The weight of the as-made zeolite crystallized on the porous support, determined from the difference between the weight of the as-made zeolite membrane composite thus obtained and the weight of the porous support, is 82 g/m It was ² . When the produced membrane was subjected to XRD measurement, it was confirmed that AFX type zeolite was produced. The peak intensity of the highest peak (2θ = 17.5 [deg]) among the peaks attributed to AFX type zeolite is I ₁ , which is derived from AFX type zeolite or other crystalline phases not attributed to the porous support. When the peak intensity of the highest intensity peak (2θ=23.3[deg]) is _I2 , the peak intensity ratio _I2 / _I1 is 0.44, indicating that the AFX type has relatively high purity. It was suggested that a zeolite film was formed.
An XRD measurement chart is shown in FIG.

In this example, hydrothermal synthesis was performed in a raw material mixture containing an Al element source using a porous support to which FAU type zeolite and CHA type zeolite were attached, resulting in a relatively high purity AFX type zeolite membrane. An AFX type zeolite membrane could be formed on a porous support.

[Example 6]
<Attachment of zeolite to porous support>
A 1% by mass aqueous dispersion of proton type FAU type zeolite (SAR=200, Tosoh Corporation HSZ-390HUA) was used as the FAU type zeolite dispersion for adhesion, and alumina was removed by suctioning for 3 seconds and rubbing in the same manner as in Example 4. FAU type zeolite was deposited on the support. The amount of FAU type zeolite deposited was 6.5 g/m ² .

<Hydrothermal synthesis>
As a raw material mixture for hydrothermal synthesis, water glass 3 was mixed in advance with 0.72 g of a sodium aluminate aqueous solution (Na ₂ O 18.9 mass %, Al ₂ O ₃ 20.13 mass %, manufactured by Asada Chemical Industry Co., Ltd.). 10.90 g (manufactured by Kishida Chemical Co., Ltd.) and 8.74 g of water were added with stirring, and further 9.45 g of DABCO (17.29% by mass aqueous solution, manufactured by Seichem Co., Ltd.) was added, and the mixture was stirred at room temperature for 1 hour. A porous support-zeolite membrane composite was produced in the same manner as in Example 2, except that the synthesis time was 24 hours. The composition of the raw material mixture for hydrothermal synthesis used was 1SiO ₂ /0.033Al ₂ O ₃ /0.70NaOH/0.10DABCO/25H ₂ O (molar ratio).

<Measurement/Evaluation>
The weight of the as-made zeolite crystallized on the porous support, determined from the difference between the weight of the as-made zeolite membrane composite thus obtained and the weight of the porous support, is 70 g/m It was ² . When the produced membrane was subjected to XRD measurement, it was confirmed that AFX type zeolite was produced. The peak intensity of the highest peak (2θ = 21.9 [deg]) among the peaks attributed to AFX type zeolite is I ₁ , which is derived from AFX type zeolite or other crystalline phases not attributed to the porous support. When the peak intensity of the highest intensity peak (2θ = 22.8 [deg]) is I ₂ , the peak intensity ratio I ₂ /I ₁ is 0.40, indicating that the AFX type has relatively high purity. It was suggested that a zeolite film was formed.
An XRD measurement chart is shown in FIG.

In this example, an AFX zeolite membrane with relatively high purity was obtained by performing hydrothermal synthesis in a raw material mixture containing an Al element source using a porous support to which FAU zeolite was attached. could be formed on a porous support.

[Example 7]
<Attachment of zeolite to porous support and hydrothermal synthesis>
A porous support-zeolite membrane composite was produced in the same manner as in Example 6, except that a CHA type zeolite synthesized with a SiO ₂ /Al ₂ O ₃ ratio of 500 was used as the adhesion zeolite. The amount of CHA type zeolite deposited was 4.3 g/m ² .

<Measurement/Evaluation>
The air permeation rate of the as-made zeolite membrane composite thus obtained was 240 L/(m ² ·h), suggesting that a relatively dense membrane was obtained. The weight of the zeolite crystallized on the porous support, determined from the difference between the weight of the zeolite membrane composite after firing and the weight of the porous support, was 110 g/m ² . The air permeation amount of the zeolite membrane composite after firing was 6600 L/(m ² ·h). When the produced membrane was subjected to XRD measurement, it was confirmed that AFX type zeolite was produced. Almost no peaks derived from AFX type zeolite or other crystal phases not assigned to the porous support were observed, suggesting the formation of an extremely pure AFX type zeolite membrane. The peak intensity of the highest peak (2θ = 21.7 [deg]) among the peaks attributed to AFX type zeolite is I ₁ , which is derived from AFX type zeolite or other crystalline phases not attributed to the porous support. When the peak intensity of the peak with the highest intensity among the peaks (2θ=7.3 [deg]) was defined as I ₂ , the peak intensity ratio I ₂ /I ₁ was 0.17.
An XRD measurement chart is shown in FIG.

In this example as well, the AFX type zeolite had relatively high purity and was as-made because it was hydrothermally synthesized in a raw material mixture containing an Al element source using a porous support to which CHA type zeolite was attached. It was possible to form a dense AFX type zeolite membrane on a porous support with a relatively low amount of air permeation.

[Comparative example 2]
<Attachment of zeolite to porous support>
In the same manner as in Example 3, an alumina porous support-FAU type zeolite (Y type zeolite) membrane composite was synthesized.

<Hydrothermal synthesis>
As a raw material mixture for hydrothermal synthesis, 10.36 g of pre-mixed water glass No. 3 (manufactured by Kishida Chemical Co., Ltd.) and 2.14 g of water were added to 6.60 g of a 1 mol/l NaOH aqueous solution (manufactured by Kishida Chemical Co., Ltd.). A porous support-zeolite membrane composite was prepared in the same manner as in Example 7, except that 8.98 g of DABCO (17.29% by mass aqueous solution manufactured by Seichem) was added and stirred at room temperature for 1 hour. was manufactured. The composition of the raw material mixture for hydrothermal synthesis used was 1SiO ₂ /0Al ₂ O ₃ /0.767NaOH/0.10DABCO/25H ₂ O (molar ratio).

<Measurement/Evaluation>
The air permeation rate of the as-made zeolite membrane composite thus obtained was as high as 250 L/(m ² ·h). The weight of the zeolite crystallized on the porous support, determined from the difference between the weight of the zeolite membrane composite after firing and the weight of the porous support, was 93 g/m ² . The air permeation amount of the zeolite membrane composite after firing was 2800 L/(m ² ·h). When the produced membrane was subjected to XRD measurement, it was confirmed that AFX type zeolite was produced. Almost no peaks derived from AFX type zeolite or other crystal phases not assigned to the porous support were observed, suggesting the formation of an extremely pure AFX type zeolite membrane. The peak intensity of the highest peak (2θ = 21.8 [deg]) among the peaks attributed to AFX type zeolite is I ₁ , which is derived from AFX type zeolite or other crystalline phases not attributed to the porous support. When the peak intensity of the peak with the highest intensity among the peaks (2θ=32.3 [deg]) was defined as I ₂ , the peak intensity ratio I ₂ /I ₁ was 0.18.
An XRD measurement chart is shown in FIG.

In this comparative example, a porous support to which FAU type zeolite was attached was used, but since the raw material mixture for hydrothermal synthesis does not contain an Al element source, an AFX type zeolite membrane was synthesized on the porous support. However, it can be seen that the amount of air permeation is high in as-made, and the AFX type zeolite membrane is not dense.

[Example 8]
<Attachment of zeolite to porous support>
In the same manner as in Comparative Example 2, an alumina porous support-FAU type zeolite (Y type zeolite) membrane composite was synthesized.

<Hydrothermal synthesis>
As a raw material mixture for hydrothermal synthesis, water glass 3 was mixed in advance with 0.27 g of a sodium aluminate aqueous solution (Na ₂ O 18.9 mass %, Al ₂ O ₃ 20.13 mass %, manufactured by Asada Chemical Industry Co., Ltd.). No. (manufactured by Kishida Chemical Co., Ltd.) 10.91 g, water 3.71 g, and 1 mol/l NaOH aqueous solution (manufactured by Kishida Chemical Co., Ltd.) 5.32 g were added while stirring, and then DABCO (17.29% by mass aqueous solution, manufactured by Seichem Co., Ltd.) 9 A porous support-zeolite membrane composite was produced in the same manner as in Comparative Example 2, except that the material obtained by adding .45 g of the porous support and stirring at room temperature for 1 hour was used. The composition of the raw material mixture for hydrothermal synthesis used was 1SiO ₂ /0.01Al ₂ O ₃ /0.767NaOH/0.10DABCO/25H ₂ O (molar ratio).

<Measurement/Evaluation>
The air permeation rate of the as-made zeolite membrane composite thus obtained was 56 L/(m ² ·h). In this example, since the zeolite membrane was manufactured in the same manner as in Comparative Example 2 except that an Al element source was added to the raw material mixture, the effect of adding the Al element source to the raw material mixture was the same as in Comparative Example 2. It was suggested that the amount of air permeation in as-made was reduced compared to that in the case of as-made, and a denser membrane was obtained. The weight of the zeolite crystallized on the porous support, determined from the difference between the weight of the zeolite membrane composite after firing and the weight of the porous support, was 130 g/m ² . The air permeation amount of the zeolite membrane composite after firing was 2600 L/(m ² ·h). When the produced membrane was subjected to XRD measurement, it was confirmed that AFX type zeolite was produced. Almost no peaks derived from AFX type zeolite or other crystal phases not assigned to the porous support were observed, suggesting the formation of an extremely pure AFX type zeolite membrane. The peak intensity of the highest peak (2θ = 21.8 [deg]) among the peaks attributed to AFX type zeolite is I ₁ , which is derived from AFX type zeolite or other crystalline phases not attributed to the porous support. When the peak intensity of the peak with the highest intensity among the peaks (2θ=6.2 [deg]) was defined as I ₂ , the peak intensity ratio I ₂ /I ₁ was 0.30.
An XRD measurement chart is shown in FIG.

In this example as well, hydrothermal synthesis was performed in a raw material mixture containing an Al element source using a porous support to which FAU type zeolite was attached, so that the purity of AFX type zeolite was relatively high and the Al element source was It was possible to form a dense AFX-type zeolite membrane on a porous support with clearly lower air permeation in as-made than when hydrothermal synthesis was carried out in a raw material mixture containing no zeolite.

[Example 9]
<Attachment of zeolite to porous support and hydrothermal synthesis>
Example 1 except that 0.016 g of a 20% by mass dispersion of HY10 ground with a bead mill, similar to that used as the FAU type zeolite dispersion for adhesion in Example 5, was added to the raw material mixture for hydrothermal synthesis. Similarly to 8, a zeolite membrane composite was synthesized by immersing the alumina porous support-FAU type zeolite (Y type zeolite) membrane composite in the raw material mixture for hydrothermal synthesis.

<Measurement/Evaluation>
The air permeation rate of the as-made zeolite membrane composite thus obtained was 0 L/(m ² ·h), suggesting that a dense membrane was obtained. The weight of the zeolite crystallized on the porous support, determined from the difference between the weight of the zeolite membrane composite after firing and the weight of the porous support, was 164 g/m ² . The air permeation amount of the zeolite membrane composite after firing was 94 L/(m ² ·h). When the produced membrane was subjected to XRD measurement, it was confirmed that AFX type zeolite was produced. Almost no peaks derived from AFX type zeolite or other crystal phases not assigned to the porous support were observed, suggesting the formation of an extremely pure AFX type zeolite membrane. The peak intensity of the highest peak (2θ = 21.8 [deg]) among the peaks attributed to AFX type zeolite is I ₁ , which is derived from AFX type zeolite or other crystalline phases not attributed to the porous support. When the peak intensity of the peak with the highest intensity among the peaks (2θ=41.7 [deg]) was defined as I ₂ , the peak intensity ratio I ₂ /I ₁ was 0.30.
An XRD measurement chart is shown in FIG.

Using this zeolite membrane composite, a single component gas permeation test was conducted at a test temperature of 140°C, a supply gas pressure of 0.4 MPa, and a permeate gas pressure of atmospheric pressure, and the CO ₂ permeance (P _CO2 ) was 9. 25×10 ⁻⁸ [mol・(m ²・s・Pa) ⁻¹ ], _CH4 gas permeance P _CH4 is 1.50×10 ⁻⁸ [mol・(m ²・s・Pa) ⁻¹ ], The permeance ratio P _CO2 /P _CH4 was 6.2.
Since the permeance ratio P _CO2 /P _CH4 in the entire zeolite membrane was larger than the permeance ratio P _CO2 /P _CH4 in Knudsen diffusion, it was found that CO ₂ selectively permeated through the zeolite pores. Therefore, it was suggested that this zeolite membrane has CO ₂ /CH ₄ separation ability derived from the molecular sieve of AFX type zeolite pores.

In this example as well, the AFX type zeolite has a very high purity because it was hydrothermally synthesized in a raw material mixture containing an Al element source using a porous support to which the FAU type zeolite was attached, and it was as-made. A dense AFX-type zeolite membrane with a low air permeation rate could be formed on a porous support, and a zeolite membrane composite with a high separation effect due to molecular sieving action could be obtained.

[Example 10]
<Attachment of zeolite to porous support and hydrothermal synthesis>
0.015 g of powder of proton type FAU type zeolite (SAR = 200, Tosoh Corporation HSZ-390HUA) similar to that used as the FAU type zeolite for adhesion in Example 6 was added to the raw material mixture for hydrothermal synthesis. Otherwise, a zeolite membrane composite was synthesized in the same manner as in Example 8 by immersing the alumina porous support-FAU type zeolite (Y type zeolite) membrane composite in the raw material mixture for hydrothermal synthesis.

<Measurement/Evaluation>
The air permeation rate of the as-made zeolite membrane composite thus obtained was 0 L/(m ² ·h), suggesting that a dense membrane was obtained. The weight of the zeolite crystallized on the porous support, determined from the difference between the weight of the zeolite membrane composite after firing and the weight of the porous support, was 142 g/m ² . The air permeation amount of the zeolite membrane composite after firing was 167 L/(m ² ·h). When the produced membrane was subjected to XRD measurement, it was confirmed that AFX type zeolite was produced. Almost no peaks derived from AFX type zeolite or other crystal phases not assigned to the porous support were observed, suggesting the formation of an extremely pure AFX type zeolite membrane. The peak intensity of the highest peak (2θ = 21.8 [deg]) among the peaks attributed to AFX type zeolite is I ₁ , which is derived from AFX type zeolite or other crystalline phases not attributed to the porous support. When the peak intensity of the peak with the highest intensity among the peaks (2θ=18.8 [deg]) was defined as I ₂ , the peak intensity ratio I ₂ /I ₁ was 0.34.
An XRD measurement chart is shown in FIG.

Using this zeolite membrane composite, a single component gas permeation test was carried out at a test temperature of 140°C, a supply gas pressure of 0.4 MPa, and a permeate gas pressure of atmospheric pressure, and the CO ₂ permeance (P _CO2 ) was 1. 94×10 ⁻⁷ [mol・(m ²・s・Pa) ⁻¹ ], _CH4 gas permeance P _CH4 is 1.50×10 ⁻⁸ [mol・(m ²・s・Pa) ⁻¹ ], The permeance ratio P _CO2 /P _CH4 was 6.2.
Since the permeance ratio P _CO2 /P _CH4 in the entire zeolite membrane was larger than the permeance ratio P _CO2 /P _CH4 in Knudsen diffusion, it was found that CO ₂ selectively permeated through the zeolite pores. Therefore, it was suggested that this zeolite membrane has CO ₂ /CH ₄ separation ability derived from the molecular sieve of AFX type zeolite pores.

In this example as well, the AFX type zeolite has a relatively high purity because it was hydrothermally synthesized in a raw material mixture containing an Al element source using a porous support to which FAU type zeolite was attached, and it was as-made. A dense AFX-type zeolite membrane with a low air permeation rate could be formed on a porous support, and a zeolite membrane composite with a high separation effect due to molecular sieving action could be obtained.

[Example 11]
<Attachment of zeolite to porous support and hydrothermal synthesis>
An alumina porous support-FAU type zeolite (Y type zeolite) membrane composite was synthesized in the same manner as in Example 3, except that the composition of the raw material mixture for hydrothermal synthesis was changed. A raw material mixture for hydrothermal synthesis was obtained in the same manner as in Example 3, and then DABCO (19.8% by mass aqueous solution, manufactured by Seichem) was added and stirred for 1 minute to determine the composition of the raw material mixture for hydrothermal synthesis. It was used as 1SiO2 _{/ 0.1Al2O3 /} 2.8NaOH _/ 84H2O/0.1DABCO (molar ratio). Example 8 except that 1.24 g of a 20% by mass dispersion of HY10 ground with a bead mill, similar to that used as the FAU type zeolite dispersion for adhesion in Example 5, was added to the raw material mixture for hydrothermal synthesis. In the same manner as above, the alumina porous support-FAU type zeolite (Y type zeolite) membrane composite obtained by the above method was immersed in a raw material mixture for hydrothermal synthesis to synthesize a zeolite membrane composite.

<Measurement/Evaluation>
The air permeation rate of the as-made zeolite membrane composite thus obtained was 80 L/(m ² ·h), suggesting that a relatively dense membrane was obtained. The weight of the zeolite crystallized on the porous support, determined from the difference between the weight of the zeolite membrane composite after firing and the weight of the porous support, was 136 g/m ² . The air permeation amount of the zeolite membrane composite after firing was 589 L/(m ² ·h). When the produced membrane was subjected to XRD measurement, it was confirmed that AFX type zeolite was produced. Almost no peaks derived from AFX type zeolite or other crystal phases not assigned to the porous support were observed, suggesting the formation of an extremely pure AFX type zeolite membrane. The peak intensity of the highest peak (2θ = 21.9 [deg]) among the peaks attributed to AFX type zeolite is I ₁ , which is derived from AFX type zeolite or other crystalline phases not attributed to the porous support. When the peak intensity of the peak with the highest intensity among the peaks (2θ=7.1 [deg]) was defined as I ₂ , the peak intensity ratio I ₂ /I ₁ was 0.30.
An XRD measurement chart is shown in FIG.

Using this zeolite membrane composite, a two-component mixed gas permeation test was conducted at a test temperature of 50°C, a supply gas pressure of 0.4 MPa, a permeation gas pressure of atmospheric pressure, and a supply gas linear velocity of 40 cm/s. , when the supply gas composition CO ₂ /CH ₄ =50/50, the CO ₂ permeance (P _CO2 ) is 3.65×10 ⁻⁷ [mol・(m ²・s・Pa) ⁻¹ ], and the CH ₄ gas permeance The ence P _CH4 was 2.95×10 ⁻⁸ [mol·(m ² ·s·Pa) ⁻¹ ], and the permeance ratio P _CO2 /P _CH4 was 12.4. Furthermore, when the supply gas composition CO ₂ /N ₂ = 50/50, the CO ₂ permeance (P _CO2 ) is 3.36×10 ⁻⁷ [mol・(m ²・s・Pa) ⁻¹ ], and the N ₂ gas The permeance P _N2 was 3.62×10 ⁻⁸ [mol·(m ² ·s·Pa) ⁻¹ ], and the permeance ratio P _CO2 /P _N2 was 9.29.
Since the permeance ratio P _CO2 /P _CH4 in the entire zeolite membrane was larger than the permeance ratio P _CO2 /P _CH4 in Knudsen diffusion, it was found that CO ₂ selectively permeated through the zeolite pores. Therefore, it was suggested that this zeolite membrane has CO ₂ /CH ₄ separation ability derived from the molecular sieve of AFX type zeolite pores.
Furthermore, since the pore diameter of N ₂ molecules is larger than that of AFX type zeolite, it is expected that all of the N 2 molecules will diffuse through the zeolite grain boundaries rather than through the zeolite pores and pass through the membrane. Assuming that the diffusion of CO ₂ and N ₂ at the grain boundaries in the zeolite film is Knudsen diffusion, the permeance ratio P _CO2 /P _N2 at the defect can be calculated as 0.798 from the following formula.
P _CO2 /P _CH4 = (MW _N2 ×T) ^0.5 / (MW _CO2 ×T) ^0.5
(MW _CO2 and MW _N2 are the molecular weights of _CO2 and _N2 , respectively, T is the test temperature [K])
Since the permeance ratio P _CO2 /P _N2 in the entire zeolite membrane was larger than the permeance ratio P _CO2 /P _N2 in Knudsen diffusion, it was found that CO ₂ selectively permeated through the zeolite pores. Therefore, it was suggested that this zeolite membrane has CO ₂ /N ₂ separation ability derived from the molecular sieve of AFX type zeolite pores.

In this example as well, AFX type zeolite has relatively high purity and is as-made because it was hydrothermally synthesized in a raw material mixture containing an Al element source using a porous support to which FAU type zeolite was attached. A dense AFX-type zeolite membrane with a relatively low air permeation rate could be formed on a porous support, and a zeolite membrane composite with a high separation effect due to molecular sieving action could be obtained.

From the above, it was found that the porous support-AFX type zeolite membrane composite obtained by the method of the present invention exhibits a separation effect even for small molecules such as nitrogen due to the molecular sieving action. This is considered to be due to the fact that the AFX type zeolite forming the AFX type zeolite membrane has high purity, the membrane is dense, and gas molecules permeate through the pores of the AFX type zeolite.

1 Porous support-zeolite membrane composite 2 Pressure-resistant container 3 End pin 4 Connection part 5 Pressure gauge 6 Back pressure valve 7 Sample mixture 8 Permeated component 9 Sweep fluid 10 Concentrated component 11 Piping 12 Piping

Claims (3)

A method for producing a porous support-zeolite membrane composite having an AFX type zeolite membrane on a porous support, the method comprising:
A step of attaching FAU type zeolite or CHA type zeolite to the surface of the porous support;
immersing the porous support in a raw material mixture to perform hydrothermal synthesis,
The raw material mixture contains at least one of a nitrogen-containing six-membered ring compound, a dimer structure compound obtained by crosslinking nitrogen atoms of an amine, and a nitrogen-containing five-membered ring compound. and a method for producing a porous support-zeolite membrane composite containing either one or both of sodium aluminate and amorphous aluminosilicate . The method for producing a porous support-zeolite membrane composite according to claim 1, wherein the FAU type zeolite or the CHA type zeolite is in powder form. The method for producing a porous support-zeolite membrane composite according to claim 1, wherein the FAU type zeolite or CHA type zeolite is in the form of a membrane.

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