JP7163951B2 - Zeolite membrane composite - Google Patents

Description

The present invention relates to zeolite membrane composites, and more particularly to zeolite membrane composites used to separate a specific component from a multicomponent gas mixture, wherein the zeolite membrane exhibits specific physicochemical properties. and a zeolite membrane composite formed on an inorganic porous support, and a method for separating or concentrating a gas mixture using the zeolite membrane composite as a separation means.

Gas separation and purification methods include membrane separation, adsorption separation, absorption separation, distillation separation, and cryogenic separation. This is a method of separating by the difference in the velocity of the gas permeating the membrane, using the pressure difference as the driving energy. The membrane separation method is easier to handle than other gas separation/purification methods, and the scale of equipment is relatively small.

As a gas separation method using a membrane, a method using a polymer membrane has been proposed since the 1970s. However, while polymer membranes are characterized by their excellent workability, they have the problem of being degraded by heat, chemicals, and pressure, resulting in reduced performance.
In recent years, in order to solve these problems, various inorganic films having good chemical resistance, oxidation resistance, heat stability and pressure resistance have been proposed. Among them, zeolite has regular pores of sub-nanometer size, so it works as a molecular sieve, so it can selectively permeate specific molecules, and is expected to exhibit high separation performance.

Specific examples of membrane separation of mixed gases include carbon dioxide and nitrogen, carbon dioxide and methane, hydrogen and hydrocarbons, hydrogen and oxygen, hydrogen and Separation of carbon dioxide, nitrogen and oxygen, paraffins and olefins, etc. Zeolite membranes such as A-type membranes, FAU membranes, MFI membranes, SAPO-34 membranes and DDR membranes are known as usable zeolite membranes for gas separation.

The A-type zeolite membrane is easily affected by moisture, it is difficult to make a membrane without crystal gaps, and the separation performance is not high. The FAU membrane has zeolite pores of 0.6 to 0.8 nm, which are large enough for two gas molecules to enter the zeolite pores. This membrane is suitable for the separation of molecules with and without zeolite pore adsorption properties, such as the separation of carbon dioxide and nitrogen. However, non-adsorptive molecules are difficult to separate, and the scope of application is narrow. The pore diameter of the MFI membrane is 0.55 nm, and the pores are rather large for separating gas molecules, and the separation performance is not high.

In addition, separation of carbon dioxide and methane is desired in natural gas refining plants and plants that generate biogas by methane fermentation of kitchen waste. DDR (Patent Document 1), SAPO-34 (Non-Patent Document 1), and SSZ-13 (Non-Patent Document 2) are known as films with good performance, which utilize a molecular sieve function.

JP-A-2004-105942

Shiguang Li et al., "Improved SAPO-34 Membranes for CO2/CH4Separation", 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, 3458-3464

However, DDR (Patent Document 1) has good separation performance, but has a low carbon dioxide permeance (also referred to as "permeability") because the zeolite structure is two-dimensional. SAPO-34 (Non-Patent Document 1), which is a CHA-type aluminophosphate having a three-dimensional structure, has good separation performance and permeance, but deteriorates in the presence of water.

In addition, in chemical plants, mixed gas often contains moisture, and in some cases the performance deteriorates in the coexistence of water, making it unusable for practical use. SSZ-13 (Non-Patent Document 2), which is a CHA-type aluminosilicate that is also a SUS support membrane, has insufficient separation performance due to the coexistence of non-zeolite pores (defects) in the zeolite membrane, and carbon dioxide was not sufficient. Such separation membranes for gaseous mixtures that can withstand practical use have not been known.

An object of the present invention is to provide a zeolite membrane composite having excellent water resistance and excellent properties in separating gas mixtures, in which the problems of the prior art are solved.

As a result of intensive studies by the present inventors to solve the above problems, when a zeolite membrane is formed on a porous support by hydrothermal synthesis, if a reaction mixture with a specific composition is used, We found that the crystal orientation of the crystallized zeolite is improved, and in the separation of a mixture of organic compounds and water, a dense zeolite membrane is formed that achieves both a practically sufficient throughput and separation membrane performance. (International Publication No. 2010/098473 pamphlet, JP-A-2011-121040, JP-A-2011-121045, JP-A-2011-121854). As a result of further studies, the present inventors have found that by incorporating a certain kind of metal into these zeolite membrane composites, they can provide membrane separation means with excellent gas mixture separation performance and large throughput. have arrived at the present invention.

That is, the gist of the present invention resides in the following (1) to (11).
(1) A zeolite membrane composite used for permeating and separating highly permeable components from a gas mixture consisting of a plurality of components, at least one selected from the group consisting of divalent or higher metals excluding Al A zeolite membrane composite comprising a zeolite membrane containing a CHA-type aluminosilicate zeolite containing a seed metal and formed on an inorganic porous support.
(2) The zeolite membrane composite according to (1), wherein the divalent or higher metals are Mg, Fe, Ga, La, Cr, Zr, Sn and Ti.
(3) The zeolite membrane composite according to (1) or (2), wherein the zeolite has a SiO ₂ /Al ₂ O ₃ molar ratio of 6 or more and 100 or less.
(4) In the X-ray diffraction pattern obtained by irradiating the surface of the zeolite membrane with X-rays, the peak intensity near 2θ = 17.9° is 0.5 of the peak intensity near 2θ = 20.8°. The zeolite membrane composite according to any one of (1) to (3), which has a value more than double.
(5) In the X-ray diffraction pattern obtained by irradiating the surface of the zeolite membrane with X-rays, the peak intensity near 2θ = 9.6° is 2.0 of the peak intensity near 2θ = 20.8°. The zeolite membrane composite according to any one of (1) to (4), which has a value more than double.
(6) The zeolite membrane composite has an air permeation rate of 0 L/(m ² h) or more and 900 L/(m ² h) or less when connected to a vacuum line with an absolute pressure of 5 kPa, (1) to ( The zeolite membrane composite according to any one of 5).
(7) The zeolite membrane composite according to any one of (1) to (6), wherein the zeolite membrane is formed using a reaction mixture for hydrothermal synthesis containing at least potassium (K) as an alkali source. body.
(8) A zeolite membrane composite, in which a zeolite membrane containing a CHA-type aluminosilicate zeolite is formed on an inorganic porous support, is coated with at least one selected from the group consisting of divalent or higher metals excluding Al. The zeolite membrane composite according to any one of (1) to (7), which is obtained by contacting with an aqueous solution containing metal ions.
(9) A zeolite membrane composite used for permeating and separating a highly permeable component from a gas mixture consisting of a plurality of components, wherein the zeolite membrane containing CHA-type aluminosilicate zeolite is inorganic porous support It is obtained by contacting the zeolite membrane composite formed on the body with an aqueous solution containing ions of at least one metal selected from the group consisting of divalent or higher metals excluding Al. A zeolite membrane composite characterized by:
(10) The zeolite membrane composite according to any one of (1) to (9) is brought into contact with a gas mixture composed of a plurality of components, and a highly permeable component is permeated and separated from the gas mixture. Alternatively, a method for separating or concentrating a gaseous mixture, characterized in that a component with low permeability is concentrated by permeating and separating a component with high permeability.
(11) the gas mixture contains carbon dioxide, hydrogen, oxygen, nitrogen, methane, ethane, ethylene, propane, propylene, normal butane, isobutane, 1-butene, 2-butene, isobutene, sulfur hexafluoride, helium, monoxide The method according to (10), which contains at least one component selected from the group consisting of carbon, nitric oxide and water.

According to the present invention, it has excellent chemical resistance, heat stability, oxidation resistance, pressure resistance, a large amount of gas permeation, a high separation factor, high wet heat stability, and excellent separation of gas mixtures. A zeolite membrane composite can be provided. In addition, by using the zeolite membrane composite of the present invention as means for separating gas mixtures, gas separation can be carried out with high performance with small-scale equipment, energy saving, and low cost.

Further, according to the present invention, a highly permeable gas is permeated from the gas mixture, and a less permeable gas is concentrated, thereby separating the highly permeable gas from the system and removing the less permeable gas. By concentrating and recovering, the target gas can be separated from the gas mixture with high purity.

It is a schematic diagram of the apparatus used for the permeation test of single-component gas. It is a schematic diagram of the apparatus used for gas separation. It is a schematic diagram of the apparatus used for the vapor permeation method. 4 is an XRD pattern of the CHA-type zeolite membrane produced in Preparation Example 1. FIG. Fig. 3 is an XRD pattern of powdered CHA-type zeolite; 4 is an XRD pattern of the CHA-type zeolite membrane produced in Preparation Example 2. FIG. 4 is an XRD pattern of the CHA-type zeolite membrane produced in Preparation Example 3. FIG.

Hereinafter, the embodiments of the present invention will be described in more detail, but the description of the constituent elements described below is an example of the embodiments of the present invention, and the present invention is not limited to these contents. Various modifications can be made within the scope of the gist. In the present specification, "zeolite membrane composite formed on an inorganic porous support" is referred to as "inorganic porous support-zeolite membrane composite" and "inorganic porous support - "zeolite membrane composite" as "zeolite membrane composite" or "membrane composite", "inorganic porous support" as "porous support" or "support", and "CHA-type aluminosilicate zeolite" ” may be abbreviated as “CHA-type zeolite”.

<Porous support-zeolite membrane composite>
The zeolite membrane composite of the present invention is a zeolite membrane composite used for permeating and separating highly permeable components from a gas mixture consisting of a plurality of components, and is composed of a divalent or higher metal excluding Al. It is characterized in that a zeolite membrane containing a CHA-type aluminosilicate zeolite containing at least one metal selected from the group is formed on an inorganic porous support.

In the present invention, as described above, the zeolite membrane composite is used as a membrane separation means for permeating and separating highly permeable components from a gas mixture consisting of a plurality of components.
Matters relating to the method of separating or concentrating a gas mixture, such as gas components, separation method, separation performance, etc., will be described after the details of the zeolite membrane composite are described.

(zeolite membrane)
In the present invention, the components constituting the zeolite membrane may optionally contain inorganic binders such as silica and alumina, organic substances such as polymers, and silylating agents for modifying the zeolite surface, in addition to zeolite.
The zeolite membrane may partially contain an amorphous component or the like, but is preferably a zeolite membrane substantially composed of zeolite alone.

Although the thickness of the zeolite membrane is not particularly limited, it is usually 0.1 μm or more, preferably 0.6 μm or more, and more preferably 1.0 μm or more. Also, it is usually 100 μm or less, preferably 60 μm or less, more preferably 20 μm or less. If the film thickness is too large, the permeation amount tends to decrease, and if it is too small, the selectivity tends to decrease and the film strength tends to decrease.

The particle size of the zeolite forming the zeolite membrane is not particularly limited, but if it is too small, the grain boundary tends to become large and the permeation selectivity tends to decrease. Therefore, it is usually 30 nm or more, preferably 50 nm or more, more preferably 100 nm or more, and the upper limit is not more than the thickness of the film. Furthermore, it is more preferable if the particle size of the zeolite is the same as the thickness of the membrane. The zeolite grain boundaries are the smallest when the zeolite particle size is the same as the film thickness. A zeolite membrane obtained by hydrothermal synthesis, which will be described later, is preferable because the zeolite particle size and membrane thickness may be the same.

The shape of the zeolite membrane (the shape of the membrane composite) is not particularly limited, and any shape such as tubular, hollow fiber, monolithic, honeycomb and the like can be adopted. The size is also not particularly limited, and for example, in the case of a tubular shape, it is 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 present invention, the zeolite membrane contains at least one metal selected from the group consisting of divalent or higher valent metals excluding Al. Examples of divalent or higher metals include Mg, Fe, Ga, La, Cr, Zr, Sn, and Ti. Among these, Mg, Fe, La, Cr and Zr are preferred. As described above, these metal elements contained in the zeolite membrane may be of one type, or may be of a plurality of types in any combination.

It is believed that these metal elements are contained in the zeolite as ion-exchanged or oxides, or are substituted as part of the zeolite skeleton.

The content of this metal element can be measured by scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDX), inductively coupled plasma (ICP) elemental analysis, X-ray photoelectron spectroscopy (XPS), or the like. can. In SEM-EDX, it is desirable to quantify by preparing a calibration curve using samples whose metal element content values have been obtained by chemical analysis. ICP can be measured by dissolving the zeolite membrane portion with hydrofluoric acid or the like. XPS can measure the metal content of the film surface.

By including these metal elements, if the metal elements are present in the pores, it is thought that the effective pore size of the zeolite membrane changes according to the position of the presence and the size of the metal atoms. As the metal element content increases, the change in pore size also increases, and the preferred value of this pore size is determined by the molecular size of the component to be separated. Therefore, the suitable metal element content differs depending on the component to be separated. Even if a small amount of metal element is contained, the separation performance will be affected not a little depending on the amount, but if the target component separation performance can be achieved with a small amount, the amount of metal element less is better. In addition, when it is necessary to greatly reduce the pore size in order to achieve the target separation performance, such as when the component molecules to be separated are all very small, the higher the metal element content, the better. . However, if the metal element content is too large, the pores tend to be clogged, making it difficult for gas to permeate.

In addition, a metal element with a low ionization tendency can become an oxide and exist outside the pores. When it is present outside the pores, if the location of its presence is a membrane defect, it is thought that it acts to fill the membrane defect, leading to an improvement in separation performance. When the film has many defects, the content of the metal element is preferably large, and when the film has few defects, the content may be small. If there are too many metal elements outside the pores, the entrances to the pores may be blocked and the permeability may decrease.

Alternatively, when a metal element is incorporated into the zeolite framework, the pore size is slightly affected by the atomic diameter of the metal element species. When a metal element with a large atomic diameter is taken in, the pore size tends to be large, and when a metal element with a small atomic diameter is taken in, the pore size tends to be small. Also in this case, there is a suitable pore size depending on the molecular size of the component to be separated, so it is desirable to incorporate an amount of metal into the skeleton that will result in a suitable size.

Furthermore, regardless of the state of the metal element, the component molecules that separate from the metal element may interact with each other. For example, if the inside of the zeolite pores becomes a highly polar field due to the presence of a metal element, polar molecules such as water vapor are likely to be adsorbed, and the amount of permeation tends to increase. When each molecule interacts with a metal element in this manner, the amount of permeation may be affected due to the difference in adsorption to the zeolite membrane. If the amount of the metal element is too small, the adsorption capacity cannot be sufficiently increased, and if it is too large, or depending on the combination of the metal element and the component molecules, the adsorption capacity becomes too high, and the molecules remain in the pores and do not permeate the membrane. There is

For the above reasons, the preferred content of the metal element varies depending on the component to be separated and the amount of defects in the zeolite membrane. Therefore, the content of the metal element is not particularly limited, but the molar ratio of the divalent or higher metal excluding Al to Al (bivalent or higher metal/Al molar ratio) is usually 0.0002 or more, preferably 0.0004 or more. , more preferably 0.001 or more, still more preferably 0.003 or more, still more preferably 0.006 or more, still more preferably 0.01 or more. The upper limit is usually 20 or less, preferably 15 or less, more preferably 10 or less, still more preferably 5 or less, and even more preferably 1 or less.

When the composition of the surface measured by XPS is used as a reference, the preferred value tends to differ from the overall composition due to uneven distribution of Al and metal elements. Divalent or higher metal / Al molar ratio is usually 0.0003 or more, preferably 0.0006 or more, more preferably 0.002 or more, still more preferably 0.005 or more, still more preferably 0.009 or more, and further Preferably it is 0.02 or more. The upper limit is usually 30 or less, preferably 23 or less, more preferably 15 or less, still more preferably 8 or less, more preferably 2 or less.

In addition, the "divalent or higher metal/Al molar ratio" is the molar ratio of the total amount of the divalent or higher metal excluding Al to Al.

(zeolite)
In the present invention, the zeolite constituting the zeolite membrane is CHA-type aluminosilicate. The aluminosilicate is mainly composed of oxides of Si and Al, and may contain other elements as long as the effects of the present invention are not impaired.

The effective pore size and polarity of zeolite can also be controlled by acid treatment, silylation, and the like. Separation performance can also be improved by controlling the effective pore size.

Depending on the conditions, the acid treatment tends to cause at least part of the metal introduced into the skeleton to be desorbed from the skeleton, and the metal ions present in the pores to be exchanged with H + . When the metal is detached from the framework, the amount of metal decreases, which has the effect of lowering the polarity.
Moreover, the pore size may change depending on the atomic diameter of the detached metal. Similarly, when the metal ions in the pores are exchanged with H + , the pore size and the polarity in the pores can be changed depending on the atomic diameter and polarity of the exchanged metal.

Silylation can also reduce the effective pore size of zeolites. By silylating the terminal silanols on the outer surface and laminating a silylated layer, the effective pore diameter of the pores facing the outer surface of the zeolite generally becomes smaller.

In the present invention, the SiO ₂ /Al ₂ O ₃ molar ratio of the aluminosilicate is not particularly limited. More preferably 35 or more, particularly preferably 40 or more. The upper limit is usually about the amount of Al as an impurity, and the SiO ₂ /Al ₂ O ₃ molar ratio is usually 500 or less, preferably 100 or less, more preferably 90 or less, even more preferably 80 or less, further preferably 65. 48 or less is particularly preferable. If the SiO ₂ /Al ₂ O ₃ molar ratio is less than the above lower limit, the density of the zeolite membrane may decrease, and durability tends to decrease.
The SiO ₂ /Al ₂ O ₃ molar ratio can be adjusted by the reaction conditions for hydrothermal synthesis, which will be described later.

The SiO ₂ /Al ₂ O ₃ molar ratio is a numerical value obtained by scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDX). The X-ray acceleration voltage is usually measured at 10 kV in order to obtain information only on films of a few microns.

(CHA-type zeolite)
In the present invention, the CHA-type zeolite is a code that defines the structure of zeolite defined by the International Zeolite Association (IZA) and has a CHA structure. It is a zeolite with a crystal structure similar to that of naturally occurring chabazite. CHA-type zeolites have a structure characterized by having three-dimensional pores consisting of eight-membered oxygen rings with diameters of 0.38×0.38 nm, and the structure is characterized by X-ray diffraction data.

The framework density (T/nm3) of CHA-type zeolite is 14.5. Also, the SiO ₂ /Al ₂ O ₃ molar ratio is the same as above.
Here, the framework density (T/nm ³ ) means the number of elements (T elements) other than oxygen constituting the framework per nm ³ (1000 Å 3) of zeolite, and this value depends on the structure of the zeolite. It is decided. The relationship between framework density and zeolite structure is shown in ATLAS OF ZEOLITE FRAMEWORK TYPES Fifth Revised Edition 2001 ELSEVIER.

(Inorganic porous support)
The inorganic porous support may be any porous inorganic material having chemical stability such that zeolite can be crystallized into a film on its surface. Specifically, for example, ceramic sintered bodies such as silica, α-alumina, γ-alumina, mullite, zirconia, titania, yttria, silicon nitride, silicon carbide, sintered metals such as iron, bronze and stainless steel, and glass , carbon moldings, and the like.

Among the inorganic porous supports, the ceramic sintered body has the effect of increasing the adhesiveness of the interface by partly converting to zeolite during the synthesis of the zeolite membrane.
Furthermore, since the inorganic porous support containing at least one of alumina, silica, and mullite is easy to partially convert to zeolite, the bond between the support and zeolite is strong, resulting in a dense separation performance. It is more preferable because a high film can be easily formed.

The shape of the support is not particularly limited as long as the gas mixture can be effectively separated. honeycombs and monoliths.
In the present invention, a zeolite membrane is formed on the surface of an inorganic porous support or the like, preferably the zeolite is crystallized into a membrane.

The average pore diameter of the support is not particularly limited, but the pore diameter is preferably controlled and is usually 0.02 μm or more, preferably 0.05 μm or more, more preferably 0.1 μm or more, and usually 20 μm or less. , preferably 10 μm or less, more preferably 5 μm or less. If the pore size is too small, the permeation amount tends to be small, and if it is too large, the strength of the support itself tends to be insufficient, and it tends to be difficult to form a dense zeolite membrane.

The surface of the support is preferably smooth, and if necessary, the surface may be polished with a file or the like. In addition, the surface of the support means the surface portion of the support on which the zeolite membrane is formed. For example, in the case of a cylindrical tube support, it may be the outer surface, the inner surface, or in some cases both the outer and inner surfaces.

The porosity of the support is not particularly limited and need not be particularly controlled, but the porosity is preferably 20% or more and 60% or less. The porosity affects the permeation flow rate during separation of gas and liquid. If the porosity is less than the lower limit, diffusion of the permeate tends to be inhibited, and if the porosity exceeds the upper limit, the strength of the support tends to decrease.

(Zeolite membrane composite)
A zeolite membrane composite is a membrane in which zeolite is adhered to the surface of a support or the like, and in some cases, a part of the zeolite is adhered to the inside of the support. preferable.

As the zeolite membrane composite, for example, one obtained by crystallizing zeolite in the form of a membrane on the surface of a support or the like by hydrothermal synthesis is preferable.

The position of the zeolite membrane on the support is not particularly limited, and when a tubular support is used, the zeolite membrane may be attached to the outer surface, the inner surface, or both sides depending on the application system. good too. Moreover, it may be laminated on the surface of the support, or may be crystallized so as to fill the pores of the surface layer of the support. In this case, it is important that there are no cracks or continuous micropores inside the crystallized film layer, and formation of a so-called dense film improves separation.

In the zeolite membrane composite of the present invention, in the X-ray diffraction pattern obtained by irradiating the membrane surface with X-rays, the intensity of the peak near 2θ = 17.9 ° is the intensity of the peak near 20.8 ° is preferably 0.5 times or more.

Here, the peak intensity refers to the measured value minus the background value. (Intensity of peak near 2θ = 17.9°)/(Intensity of peak near 2θ = 20.8°) peak intensity ratio (hereinafter sometimes referred to as “peak intensity ratio A”) In other words, it is preferably 0.5 or more, more preferably 0.8 or more. Although the upper limit is not particularly limited, it is usually 1000 or less.

In addition, in the zeolite membrane composite in the present invention, in the X-ray diffraction pattern, the intensity of the peak near 2θ = 9.6° is 2.0 times or more the intensity of the peak near 2θ = 20.8°. is preferably

(Intensity of peak near 2θ = 9.6°)/(Intensity of peak near 2θ = 20.8°) Peak intensity ratio (hereinafter sometimes referred to as “peak intensity ratio B”) In other words, it is preferably 2.0 or more, more preferably 2.5 or more, more preferably 3 or more, still more preferably 4 or more, still more preferably 6 or more, still more preferably 8 or more, and particularly preferably 10 or more. . Although the upper limit is not particularly limited, it is usually 1000 or less.

The X-ray diffraction pattern referred to here is obtained by irradiating the surface on the side where the zeolite is mainly adhered with X-rays from CuKα as a radiation source, with the scanning axis set to θ/2θ. The shape of the sample to be measured can be anything as long as the surface of the membrane composite on which the zeolite is mainly attached can be irradiated with X-rays. Whole bodies or cut to appropriate sizes as constrained by equipment are preferred.

When the surface of the zeolite membrane composite is curved, the X-ray diffraction pattern referred to here may be measured by fixing the irradiation width using an automatically variable slit. The X-ray diffraction pattern in the case of using an automatically variable slit refers to a pattern subjected to variable→fixed slit correction.

Here, the peak near 2θ=17.9° refers to the maximum peak present in the range of 17.9°±0.6° among the peaks not derived from the substrate.

The peak near 2θ=20.8° refers to the largest peak present in the range of 20.8°±0.6° among the peaks not derived from the substrate.

The peak near 2θ=9.6° refers to the largest peak present in the range of 9.6°±0.6° among the peaks not derived from the base material.

According to COLLECTION OF SIMULATED XRD POWDER PATTERNS FOR ZEOLITE Third Revised Edition 1996 ELSEVIER, the peak near 2θ = 9.6° in the X-ray diffraction pattern is rhombohedral setting.

(No. 166), this is a peak derived from a plane with an index of (1, 0, 0) in the CHA structure.

Also, according to COLLECTION OF SIMULATED XRD POWDER PATTERNS FOR ZEOLITE Third Revised Edition 1996 ELSEVIER, the peak near 2θ = 17.9° in the X-ray diffraction pattern is rhombohedral setting.

(No. 166), this is a peak derived from a plane with an index of (1, 1, 1) in the CHA structure.

According to COLLECTION OF SIMULATED XRD POWDER PATTERNS FOR ZEOLITE Third Revised Edition 1996 ELSEVIER, the peak near 2θ = 20.8° in the X-ray diffraction pattern is rhombohedral setting.

(No. 166), this is a peak derived from a plane with an index of (2, 0, −1) in the CHA structure.

A typical ratio (peak intensity ratio B) of the peak intensity derived from the (1,0,0) plane and the peak intensity derived from the (2,0,-1) plane in the zeolite membrane of CHA-type aluminosilicate is , which is less than 2 according to Non-Patent Document 2.

Therefore, when this ratio is 2.0 or more, for example, when the CHA structure is rhombohedral setting, the (1,0,0) plane of the zeolite is oriented nearly parallel to the surface of the membrane composite. This is considered to mean that the crystals are oriented and growing. Oriented growth of zeolite crystals in the zeolite membrane composite is advantageous in that a dense membrane with high separation performance can be formed.

A typical ratio (peak intensity ratio A) of the peak intensity derived from the (1,1,1) plane and the peak intensity derived from the (2,0,-1) plane is 0 according to Non-Patent Document 2. is less than .5.

Therefore, when this ratio is 0.5 or more, for example, when the CHA structure is rhombohedral setting, the (1,1,1) plane of the zeolite is oriented nearly parallel to the surface of the membrane composite. This is considered to mean that the crystals are oriented and growing. Oriented growth of zeolite crystals in the zeolite membrane composite is advantageous in that a dense membrane with high separation performance can be formed.

Thus, the fact that one of the peak intensity ratios A and B is a value within the above-described specific range means that the zeolite crystals are oriented and grow, and a dense membrane with high separation performance is formed. is shown.

Here, the larger the peak intensity ratios A and B, the stronger the degree of orientation, and generally, the stronger the degree of orientation, the denser the film is formed. In general, the stronger the orientation, the higher the separation performance. However, depending on the mixture to be separated, the optimum degree of orientation for high separation performance differs. It is desirable to select and use membrane composites.

A dense zeolite membrane in which CHA-type zeolite crystals are oriented and grown is produced by, for example, using a specific organic template in an aqueous reaction mixture when forming a zeolite membrane by a hydrothermal synthesis method, as described below. can be achieved by allowing K + ions to coexist.

<Method for producing zeolite membrane composite>
In the present invention, the method for producing a zeolite membrane is not particularly limited as long as it is a method capable of forming the specific zeolite membrane described above. (2) a method of fixing CHA-type zeolite to a support with an inorganic binder or an organic binder; (3) a method of fixing a polymer in which CHA-type zeolite is dispersed; A method of adding a specific metal element to the zeolite membrane composite produced by, for example, a method of fixing the zeolite to a support by impregnating the zeolite with the zeolite and optionally aspirating the zeolite to the support, or hydrothermally synthesizing the zeolite. In some cases, any method such as a method of adding a specific metal element to a reaction mixture for hydrothermal synthesis (hereinafter sometimes referred to as "aqueous reaction mixture") can be used.

Among these, the method of crystallizing zeolite in the form of a film on an inorganic porous support and adding a metal element by post-treatment is particularly preferred.
Although the method of crystallization is not particularly limited, a method of crystallizing zeolite on the surface of the support by directly hydrothermally synthesizing the support in a reaction mixture for hydrothermal synthesis used for zeolite production is available. preferable.

Specifically, for example, an aqueous reaction mixture whose composition has been adjusted and homogenized may be placed in a heat-resistant and pressure-resistant container such as an autoclave in which a support is loosely fixed, sealed, and heated for a certain period of time.

The aqueous reaction mixture preferably contains an elemental Si source, an elemental Al source, an alkalinity source, water, and optionally an organic template.

Examples of the Si element source used in the aqueous reaction mixture include amorphous silica, colloidal silica, silica gel, sodium silicate, amorphous aluminum silicate gel, tetraethoxysilane (TEOS), trimethylethoxysilane, and the like.

As the Al element source, for example, sodium aluminate, aluminum hydroxide, aluminum sulfate, aluminum nitrate, aluminum oxide, amorphous aluminosilicate gel and the like can be used.

The type of alkali used as the alkali source is not particularly limited, and alkali metal hydroxides, alkaline earth metal hydroxides, and hydroxide ions of counter anions of organic templates can also be used.

The metal species of metal hydroxides are usually Na, K, Li, Rb, Cs, Ca, Mg, Sr, Ba, preferably Na, K, more preferably K. Moreover, two or more kinds of metal species of the metal hydroxide may be used in combination, and specifically, it is preferable to use Na and K or Li and K together.

Specifically, examples of alkali sources include alkali metal hydroxides such as sodium hydroxide, potassium hydroxide, lithium hydroxide, rubidium hydroxide, and cesium hydroxide; calcium hydroxide, magnesium hydroxide, and strontium hydroxide. , alkaline earth metal hydroxides such as barium hydroxide and the like can be used.

As the alkalinity source used in the aqueous reaction mixture, the hydroxide ion of the counter anion of the organic template described below can be used. While the organic template serves as an alkali source, it also serves as a structure directing material even when it does not serve as an alkali source.

In the crystallization of zeolite, an organic template (structure-directing agent) can be used as necessary, but one synthesized using an organic template is preferred. Synthesis using an organic template increases the ratio of silicon atoms to aluminum atoms in the crystallized zeolite, improving crystallinity.

Any kind of organic template may be used as long as it can form a desired zeolite membrane. Also, one type of template may be used, or two or more types may be used in combination.
As organic templates, amines and quaternary ammonium salts are usually used. For example, organic templates described in US Pat. No. 4,544,538 and US Patent Publication No. 2008/0075656 are preferred.

Specific examples include cations derived from alicyclic amines such as cations derived from 1-adamantaneamine, cations derived from 3-quinaclidinal, and cations derived from 3-exo-aminonorbornene. be Among these, cations derived from 1-adamantanamine are more preferred. When a cation derived from 1-adamantaneamine is used as an organic template, a CHA-type zeolite capable of forming a dense membrane is crystallized.

Among the cations derived from 1-adamantaneamine, N,N,N-trialkyl-1-adamantanammonium cations are more preferred. The three alkyl groups of the N,N,N-trialkyl-1-adamantane ammonium cation are usually independent alkyl groups, preferably lower alkyl groups, more preferably methyl groups. The most preferred compound among them is the N,N,N-trimethyl-1-adamantane ammonium cation.

Such cations are accompanied by anions that do not interfere with the formation of CHA-type zeolites. Representatives of such anions include halogen ions such as Cl-, Br-, I-, hydroxide ions, acetates, sulfates, and carboxylates. Among these, hydroxide ions are particularly preferably used.

N,N,N-trialkylbenzylammonium cations can also be used as other organic templates. Also in this case, the alkyl groups are each independent alkyl groups, preferably lower alkyl groups, more preferably methyl groups. Among them, the most preferred compound is the N,N,N-trimethylbenzylammonium cation. Also, the anion accompanying this cation is the same as described above.

The ratio of the Si elemental source to the Al elemental source in the aqueous reaction mixture is usually expressed as the molar ratio of the oxides of the respective elements, ie, the SiO ₂ /Al ₂ O ₃ molar ratio.

The SiO ₂ /Al ₂ O ₃ ratio is not particularly limited as long as the zeolite having the above SiO ₂ /Al ₂ O ₃ ratio can be formed, but is usually 5 or more, preferably 20 or more, more preferably 30. above, more preferably 40 or more, and particularly preferably 50 or more. The upper limit is usually 500 or less, preferably 200 or less, more preferably 150 or less, and even more preferably 100 or less. When the SiO ₂ /Al ₂ O ₃ ratio is within this range, a CHA-type aluminosilicate zeolite capable of forming a dense film can be crystallized.

The ratio of the silica source to the organic template in the aqueous reaction mixture is generally 0.005 or more, preferably 0.01 or more, more preferably 0.01 or more, in terms of the molar ratio of organic template to _SiO2 (organic template/ _SiO2 ratio). 02 or more, and usually 1 or less, preferably 0.4 or less, more preferably 0.2 or less. In addition to being able to form a dense zeolite film within this range, the formed zeolite has strong acid resistance and Al is difficult to detach. Under these conditions, a particularly dense and acid-resistant CHA-type aluminosilicate zeolite can be formed.

The ratio of the Si element source to the alkali source is usually 0.02 or more, preferably 0.04 or more, more preferably 0.04 or more, in terms of M ₂ O/SiO ₂ (where M represents an alkali metal) molar ratio. 05 or more, and usually 0.5 or less, preferably 0.4 or less, more preferably 0.3 or less.

When forming a CHA-type aluminosilicate zeolite membrane, it is preferable to include potassium (K) among the alkali metals in order to form a more dense and highly crystalline membrane. In that case, the molar ratio between K and all alkali metals and/or alkaline earth metals containing K is usually 0.01 or more, preferably 0.1 or more, more preferably 0.3 or more, and the upper limit is is usually less than or equal to 1.

The addition of K into the aqueous reaction mixture constructed in accordance with the preferred embodiment of the present invention, as described above, reduces the space group to

(No. 166), the peak intensity near 2θ = 9.6 °, which is the peak derived from the (1, 0, 0) plane in the CHA structure, and the (2, 0, -1) plane Ratio of peak intensity near 2θ = 20.8°, which is a peak derived from (peak intensity ratio B), or near 2θ = 17.9°, which is a peak derived from the (1,1,1) plane There is a tendency to increase the ratio (peak intensity ratio A) between the peak intensity and the peak intensity near 2θ=20.8°, which is the peak derived from the (2, 0, −1) plane.

The ratio of the Si element source to water is usually 10 or more, preferably 30 or more, more preferably 40 or more, and particularly preferably 50 or more, in terms of the molar ratio of water to SiO ₂ (H ₂ O/SiO ₂ molar ratio). , is usually 1000 or less, preferably 500 or less, more preferably 200 or less, and particularly preferably 150 or less.

Dense zeolite membranes can be produced when the molar ratios of the substances in the aqueous reaction mixture are within these ranges. The amount of water is particularly important in the formation of a dense zeolite film, and a dense film tends to be formed more easily under conditions in which the amount of water is greater than the general conditions of the powder synthesis method.

In general, the amount of water when synthesizing powdery CHA-type aluminosilicate zeolite is about 15 to 50 in H ₂ O/SiO ₂ molar ratio. A high H ₂ O/SiO ₂ molar ratio (50 or more and 1000 or less), i.e., a condition with a large amount of water, allows separation in which the CHA-type aluminosilicate zeolite is crystallized into a dense film on the surface of the support or the like. A zeolite membrane composite with high performance can be obtained.

In the hydrothermal synthesis, by including the metal element source (ion source) in the aqueous reaction mixture, the metal can be included in the zeolite membrane at the same time as the zeolite membrane is formed. Thereby, a zeolite membrane in which the metal element is highly dispersed can be obtained.

Examples of usable metal element source compounds (metal ion source compounds) include nitrates, sulfates, acetates, phosphates, hydroxides, chlorides and complexes of the above metal elements. Among these, nitrates, sulfates and complexes are preferred. In this specification, the term "metal element source compound" and "metal ion source compound" are synonymous.

The content of the metal element source compound in the aqueous reaction mixture is usually 0.001 or more, preferably 0.005 or more, more preferably 0.01 or more, and usually 0.3 or less in molar ratio to Si. , preferably 0.2 or less, more preferably 0.1 or less.

Furthermore, in the hydrothermal synthesis, it is not always necessary to have seed crystals present in the reaction system, but the addition of seed crystals can promote the crystallization of zeolite on the support. The method of adding seed crystals is not particularly limited, and a method of adding seed crystals to an aqueous reaction mixture as in the synthesis of powdered zeolite, a method of adhering seed crystals on a support, or the like can be used. can be done. When producing a zeolite membrane composite, it is preferable to attach seed crystals to the support. By adhering seed crystals to the support in advance, a dense zeolite membrane with good separation performance can be easily formed.

The seed crystals to be used may be of any type as long as they are zeolite that promotes crystallization. However, in order to achieve efficient crystallization, the seed crystals are preferably of the same crystal type as the zeolite membrane to be formed. When forming a CHA-type aluminosilicate zeolite membrane, it is preferable to use seed crystals of CHA-type zeolite.

It is desirable that the seed crystals have a smaller particle size, and if necessary, they may be pulverized before use. The particle size is usually 0.5 nm or more, preferably 1 nm or more, more preferably 2 nm or more, and usually 5 μm or less, preferably 3 μm or less, more preferably 2 μm or less.

The method of depositing seed crystals on the support is not particularly limited. For example, a dipping method in which seed crystals are dispersed in a solvent such as water, the support is immersed in the dispersion, and the seed crystals are deposited on the surface; A method of mixing seed crystals with a solvent such as water to form a slurry and applying the slurry onto a support can be used. The dipping method is desirable for controlling the amount of seed crystals attached and producing a membrane composite with good reproducibility.

A solvent for dispersing the seed crystals is not particularly limited, but water and an alkaline aqueous solution are particularly preferable. Although the type of alkaline aqueous solution is not particularly limited, sodium hydroxide aqueous solution and potassium hydroxide aqueous solution are preferable. Also, these alkaline species may be mixed. The alkali concentration is not particularly limited, and is usually 0.0001 mol % or more, preferably 0.0002 mol % or more, more preferably 0.001 mol % or more, and still more preferably 0.002 mol % or more. Also, it is usually 1 mol % or less, preferably 0.8 mol % or less, more preferably 0.5 mol % or less, and still more preferably 0.2 mol % or less.

If the amount of seed crystals to be dispersed is too small, the amount of seed crystals adhering to the support is small, resulting in areas where zeolite is not formed partially on the surface of the support during hydrothermal synthesis, resulting in defective membranes. there is a possibility. If the amount of seed crystals in the dispersion is too large, the amount of seed crystals adhering to the support by the dipping method becomes almost constant, resulting in a large amount of waste of the seed crystals, which is disadvantageous in terms of cost.

It is desirable to attach seed crystals to the support by dipping or applying a slurry, and after drying, form the zeolite membrane.

The amount of seed crystals deposited in advance on the support is not particularly limited, and is usually 0.01 g or more, preferably 0.05 g or more, and more preferably 0.1 g or more per 1 m ² of substrate. , usually 100 g or less, preferably 50 g or less, more preferably 10 g or less, still more preferably 8 g or less.

If the amount of seed crystals is less than the lower limit, it becomes difficult to form crystals, which tends to result in insufficient film growth or non-uniform film growth. In addition, if the amount of seed crystals exceeds the upper limit, the seed crystals increase the unevenness of the surface, and the seed crystals that have fallen from the surface of the support facilitate the growth of spontaneous nuclei, hindering film growth on the support. It may be done. In either case, it tends to be difficult to form a dense zeolite membrane.

When a zeolite membrane is formed on a support by hydrothermal synthesis, there is no particular limitation on the method of immobilizing the support, and any configuration such as vertical placement or horizontal placement can be employed. In this case, the zeolite membrane may be formed by a static method, or the aqueous reaction mixture may be stirred to form the zeolite membrane.

The temperature at which the zeolite membrane is formed is not particularly limited, but is usually 100°C or higher, preferably 120°C or higher, more preferably 150°C or higher, and usually 200°C or lower, preferably 190°C or lower, and more preferably 180°C. It is below. If the reaction temperature is too low, it may become difficult to crystallize the zeolite. Also, if the reaction temperature is too high, zeolite of a type different from the zeolite of the present invention may be likely to be produced.

The heating (reaction) time is not particularly limited, but is usually 1 hour or longer, preferably 5 hours or longer, more preferably 10 hours or longer, and is usually 10 days or shorter, preferably 5 days or shorter, more preferably 3 days or shorter, and more preferably 3 days or shorter. It is preferably two days or less. If the reaction time is too short, it may become difficult to crystallize the zeolite. If the reaction time is too long, a zeolite of a different type from the zeolite of the present invention may tend to form.

The pressure during the formation of the zeolite membrane is not particularly limited, and the autogenous pressure generated when the aqueous reaction mixture placed in the closed container is heated to this temperature range is sufficient. Furthermore, if necessary, an inert gas such as nitrogen may be added.

The zeolite membrane composite obtained by hydrothermal synthesis is washed with water, then heat-treated and dried. Here, the heat treatment means drying the zeolite membrane composite by applying heat or calcining the template when the 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 for the purpose of drying. When the purpose is to bake a template, the temperature is usually 350°C or higher, preferably 400°C or higher, more preferably 430°C or higher, still more preferably 450°C or higher, and usually 900°C or lower, preferably 850°C or lower, more preferably 850°C or lower. is 800° C. or lower, particularly preferably 750° C. or lower.

The heat treatment time is not particularly limited as long as the zeolite membrane is sufficiently dried or the template is baked, and is preferably 0.5 hours or longer, more preferably 1 hour or longer. The upper limit is not particularly limited, and is usually within 200 hours, preferably within 150 hours, more preferably within 100 hours.

When hydrothermal synthesis is carried out in the presence of an organic template, the organic template can be removed by, for example, heat treatment or extraction, preferably heat treatment, that is, calcination, after washing the obtained zeolite membrane composite with water. Appropriate.

If the calcination temperature is too low, the organic template tends to remain in a large proportion, and the zeolite has few pores, which may reduce the amount of gas permeation during separation and concentration. If the sintering temperature is too high, the difference in thermal expansion coefficient between the support and the zeolite will increase, which may make the zeolite membrane more susceptible to cracking, resulting in the zeolite membrane losing its compactness and lowering the separation performance. .

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

It is desirable that the rate of temperature rise during firing be as slow as possible in order to reduce cracking of the zeolite membrane due to the difference in thermal expansion coefficient between the support and the zeolite. The heating rate is usually 5°C/min or less, preferably 2°C/min or less, more preferably 1°C/min or less, and particularly preferably 0.5°C/min or less. Usually, it is 0.1° C./min or more in consideration of workability.

Also, the cooling rate after firing must be controlled to avoid cracks in the zeolite membrane. As with the heating rate, the slower the better. The temperature drop rate is usually 5°C/min or less, preferably 2°C/min or less, more preferably 1°C/min or less, and particularly preferably 0.5°C/min or less. Usually, it is 0.1° C./min or more in consideration of workability.

The resulting zeolite membrane is then post-treated to contain metals as described above. The post-treatment method is not particularly limited as long as the membrane composite can be brought into contact with the solution containing the metal element source compound (metal ion source compound). Examples include a method of immersing the composite, a method of spraying or dropping a solution containing the metal element source compound onto the membrane composite, and the like.

Examples of the metal element source compound include nitrates, sulfates, acetates, phosphates, chlorides and metal complexes of the above metal elements, and preferably nitrates, sulfates and chlorides.

One of these metal element source compounds may be used alone, or two or more thereof may be used in any combination.

The concentration of the metal element source compound in the immersion, spraying, or dropping solution is usually 0.01 mol/L or more, preferably 0.03 mol/L or more, more preferably 0.05 mol/L or more, and usually It is 5 mol/L or less, preferably 3 mol/L or less, more preferably 1 mol/L or less.
If the concentration of the compound is too low, the effect of improving the separation performance becomes small, and if the concentration is too high, the pores tend to be clogged and the permeation amount of the component to be permeated tends to be small.

When the membrane composite is immersed in the solution containing the metal element source compound, the temperature is not particularly limited, but is usually 0°C or higher, preferably 20°C or higher, more preferably 50°C or higher, and usually 200°C or lower, preferably 200°C or higher. is 190° C. or less, more preferably 180° C. or less.

The pressure is not particularly limited, and it may be carried out in an open container under atmospheric pressure, or may be carried out in a sealed container under the autogenous pressure generated when heated to this temperature range. In the case of a closed container, if necessary, an inert gas such as nitrogen may be added.

After the immersion, it may be washed with water and then dried at a temperature of 30° C. to 120° C., or it may be dried without washing. Moreover, you may bake after drying as needed.

When the solution containing the metal element source compound is sprayed or dropped onto the membrane composite, the temperature is not particularly limited, but is usually 0° C. or higher, preferably 5° C. or higher, more preferably 10° C. or higher, and usually 100° C. or lower. , preferably 90° C. or lower, more preferably 80° C. or lower.

The pressure is not particularly limited, and the reaction is usually carried out under atmospheric pressure, but the inside of the zeolite membrane composite may be reduced in pressure.

Spraying or dripping can be performed until the surface of the zeolite membrane is wetted by the amount of the solution containing the metal element source compound exceeding the pore volume. Dry with Moreover, you may bake after drying as needed.

The firing temperature after drying is usually 200° C. or higher, preferably 250° C. or higher, more preferably 300° C. or higher, and usually 550° C. or lower, preferably 525° C. or lower, more preferably 500° C. or lower.

The baking time is not particularly limited as long as the anions such as nitrate ions are partially or completely removed, and is preferably 0.5 hours or longer, more preferably 1 hour or longer. The upper limit is not particularly limited, and is usually within 200 hours, preferably within 150 hours, more preferably within 100 hours.

It is desirable that the rate of temperature rise during firing be as slow as possible in order to reduce cracking of the zeolite membrane due to the difference in thermal expansion coefficient between the support and the zeolite. The heating rate is usually 5°C/min or less, preferably 2°C/min or less, more preferably 1°C/min or less, and particularly preferably 0.5°C/min or less. Usually, it is 0.1° C./min or more in consideration of workability.

Also, the cooling rate after firing must be controlled to avoid cracks in the zeolite membrane. As with the heating rate, the slower the better. The temperature drop rate is usually 5°C/min or less, preferably 2°C/min or less, more preferably 1°C/min or less, and particularly preferably 0.5°C/min or less. Usually, it is 0.1° C./min or more in consideration of workability.

The air permeation amount of the zeolite membrane composite after drying or firing is usually 1300 L/(m ² ·h) or less, preferably 900 L/(m ² ·h) or less, more preferably 600 L/(m ² ·h) or less. , more preferably 500 L/(m ² h) or less, still more preferably 400 L/(m ² h) or less, particularly preferably 250 L/(m ² h) or less, most preferably 150 L/(m ² h) ) below. The lower limit of the permeation amount is not particularly limited, but is usually 0 L/(m ² ·h) or more, preferably 0.01 L/(m ² ·h) or more, more preferably 0.1 L/(m ² ·h) or more, More preferably, it is 1 L/(m ² ·h) or more.

Here, the amount of air permeation is the amount of air permeation when the zeolite membrane composite is placed under atmospheric pressure and the inside of the zeolite membrane composite is connected to a vacuum line of 5 kPa, as described in detail in the section of Examples. [L/(m ² ·h)].

The amount of air permeation is a numerical value linked to the amount of gas permeation. When the amount of air permeation is large, the amount of permeation of gaseous components also increases, and when the amount of air permeation is too large, the separation tends to be low. The zeolite membrane of the present invention has a moderately high air permeation rate and sufficiently high separation performance, and has performance suitable for gas separation performance.

The zeolite membrane composite thus produced has excellent properties and can be suitably used as a means for membrane separation of gas mixtures in the present invention.

<Method for separating or concentrating gas mixture>
(Gas separation)
In the separation or concentration method of the present invention, a gas mixture composed of a plurality of components is brought into contact with the zeolite membrane composite, and a highly permeable component is permeated and separated from the gas mixture, or a highly permeable It is characterized by allowing the components to permeate and separating them, thereby concentrating the components with low permeability. One of the separation functions of the zeolite membrane in the present invention is separation as a molecular sieve, and it is possible to suitably separate gas molecules having a size equal to or larger than the effective pore size of the zeolite used and gas molecules smaller than that. can.

Therefore, the highly permeable gas component in the present invention is a gas component composed of gas molecules that easily pass through the pores of the zeolite crystal phase of the CHA-type aluminosilicate, and has a molecular diameter smaller than about 0.38 nm. Molecular gas components are preferred.

Here, in the present invention, the gas mixture to be separated is not limited to a gas (gas) at normal temperature and normal pressure, but also includes those that are liquid at normal temperature and normal pressure and can become a gas mixture by vaporization. be A method of using a vaporized gas mixture as a separation target is a separation or concentration method called a vapor permeation method (vapor permeation method), which is one embodiment of the method of the present invention. This method is particularly suitable, for example, for separating or concentrating mixtures of organic compounds and water. In this case, water is separated from the mixture and the organic compounds are concentrated in the original mixture, since water is usually highly permeable to the zeolite membrane.

In the present invention, as described above, the gas mixture to be separated is not particularly limited as long as it is a gas mixture at normal temperature and normal pressure, or can be converted into a gas mixture by vaporization.
Gas mixtures desirable as objects to be separated include, for example, carbon dioxide, hydrogen, oxygen, nitrogen, methane, ethane, ethylene, propane, propylene, normal butane, isobutane, 1-butene, 2-butene, isobutene, and sulfur hexafluoride. , helium, carbon monoxide, nitrogen monoxide, and water. Among the components of the gas mixture containing the gas, components with high permeance permeate the zeolite membrane composite and are separated, and components with low permeance are concentrated on the feed gas side.

Furthermore, the gas mixture more preferably contains at least two of the above components. In this case, the two components are preferably a combination of a high permeance component and a low permeance component.

The gas separation conditions vary depending on the type and composition of the target gas component and membrane performance, but the temperature is usually 0 to 300°C, preferably room temperature to 200°C, more preferably room temperature to 150°C.

As for the pressure of the supply gas, if the gas component to be separated is at a high pressure, the pressure may be left as it is, or the pressure may be appropriately reduced and adjusted to a desired pressure. When the pressure of the gas component to be separated is lower than the pressure used for separation, the pressure can be increased using a compressor or the like.

Although the pressure of the supplied gas is not particularly limited, it is usually atmospheric pressure or higher than atmospheric pressure, preferably 0.1 MPa or higher, more preferably 0.11 MPa or higher. Also, the upper limit is usually 20 MPa or less, preferably 10 MPa or less, more preferably 1 MPa or less.

Although the differential pressure between the gas component on the supply side and the gas component on the permeation side is not particularly limited, it is usually 20 MPa or less, preferably 10 MPa or less, more preferably 5 MPa or less, and still more preferably 1 MPa or less. Moreover, it is usually 0.001 MPa or more, preferably 0.01 MPa or more, and more preferably 0.02 MPa or more.

Here, the differential pressure means the difference between the partial pressure of the gas on the supply side and the partial pressure on the permeate side. In addition, the pressure [Pa] refers to absolute pressure unless otherwise specified.

Although the pressure on the permeation side is not particularly limited, it is usually 10 MPa or less, preferably 5 MPa or less, more preferably 1 MPa or less, and still more preferably 0.5 MPa or less. The lower limit is not particularly limited, and may be 0 MPa or higher. When the pressure is set to 0 MPa, the gas with high permeability can be separated from the gas with low permeability to the lowest concentration. If there is an application that uses the permeation side gas at a high pressure, the permeation side pressure should be set high.

The flow rate of the feed gas is selected to compensate for the reduction in gas permeation, and in the feed gas so that the concentration of the less permeable gas in the immediate vicinity of the membrane matches the concentration in the bulk of the gas. , so long as the flow rate is sufficient to mix the gases. Specifically, depending on the tube diameter of the separation unit and the separation performance of the membrane, for example, it is usually 0.5 mm / sec or more, preferably 1 mm / sec or more, and the upper limit is not particularly limited, but usually 1 m / sec or less, preferably 0.5 m/sec or less.

A sweep gas may be used in the separation or concentration method of the present invention. The method using a sweep gas is a method in which a different kind of gas from the supply gas is flowed to the permeate side, and the gas that has permeated the membrane is recovered.
The pressure of the sweep gas is usually atmospheric pressure, but is not particularly limited. .1 MPa or more. Depending on the case, it may be used under reduced pressure.

The flow rate of the sweep gas is not particularly limited, but is usually 10 ^-7 mol/(m ² ·s) or more and 104 mol/(m ² ·s) or less.

Although the device used for separating the gas mixture is not particularly limited, it is usually preferable to use it as a module (separation membrane module). The separation membrane module for separating a gaseous mixture that is a gas at normal temperature and normal pressure may be, for example, the device schematically shown in FIGS. A membrane module exemplified in Toray Research Center, 2007, page 22 may be used. The separation of gas mixtures in the apparatus of Figures 1 and 2 is described in the Examples section.

In addition, as described above, the vapor permeation method is a separation/concentration method in which a liquid mixture is vaporized and then introduced into a separation membrane, so it can be used in combination with a distillation apparatus, or can be used for separation at higher temperatures and pressures. can be used for In addition, the vapor permeation method reduces the influence of impurities contained in the feed liquid and substances that form aggregates and oligomers in the liquid state on the membrane because the liquid mixture is vaporized before being introduced into the separation membrane. can do. The zeolite membrane composite of the present invention can also be suitably used for the vapor permeation method.

When separation is performed at high temperature by the vapor permeation method, the higher the temperature and the higher the concentration of the low-permeability component in the mixture, the higher the concentration of the organic compound. The higher the concentration, the lower the separation performance, but the zeolite membrane composite of the present invention can exhibit high separation performance even at high temperatures and even when the concentration of the low-permeability component in the mixture is high. In the vapor permeation method, a liquid mixture is usually vaporized and then separated, so separation under more severe conditions is required, and durability of the zeolite membrane composite is also required. The zeolite membrane composite of the present invention is suitable for the vapor permeation method because it has durability that enables separation even under high temperature conditions.

Although the device used for separating the gas mixture by the vapor permeation method is not particularly limited, it is usually preferable to use it in the form of a module (separation membrane module). The separation membrane module may be, for example, a device as schematically shown in FIG.

In FIG. 3, a liquid 13 to be separated is sent to a vaporizer 15 at a predetermined flow rate by a liquid transfer pump 14, and the entire amount is vaporized by heating in the vaporizer 15 to become a gas to be separated. The gas to be separated is introduced into the zeolite membrane composite module 17 in the constant temperature bath 16 and supplied to the outside of the zeolite membrane composite. The zeolite membrane composite module 17 contains a zeolite membrane composite in a housing. The inside of the zeolite membrane composite is evacuated by a vacuum pump 21 . The pressure difference with the gas to be separated is usually about 1 atm. The internal pressure can be measured with a Pirani gauge (not shown). Due to this pressure difference, water, which is a permeable substance in the gas to be separated, permeates the zeolite membrane composite. The permeated substance is collected by a trap 19 for collecting permeated liquid. On the other hand, components in the gas to be separated that have not permeated are liquefied and collected by the trap 18 for recovering the liquid to be separated.

(separation performance)
The zeolite membrane composite in the present invention is excellent in chemical resistance, oxidation resistance, heat stability and pressure resistance, exhibits high permeation performance and separation performance, and has excellent durability. In particular, it exhibits excellent separation performance for separation of inorganic gases and lower hydrocarbons.

The ^{high permeation} performance referred to here indicates a sufficient throughput. When permeated at a temperature of 50 ° C. and a differential pressure of 0.1 MPa, it is usually 1 × 10 ^-9 or more, preferably 5 × 10 ^-8 or more, more preferably 1 × 10 ^-7 or more, and the upper limit is not particularly limited. , usually less than 1×10 ⁻⁴ .

In addition, the permeance [mol·(m ² ·s·Pa) ⁻¹ ] is usually 2×10 ⁻⁷ or less, preferably 1×10 ⁻⁸ or less, more preferably 1×10 −8 or less, when methane is permeated under the same conditions, It is 5×10 ⁻⁹ or less, and ideally the permeance is 0, but in practice it may be on the order of 10 ⁻¹⁰ to 10 ⁻¹⁴ or more.

Here, permeance (also referred to as "permeability") is the amount of permeating substance divided by the product of the membrane area, time, and the partial pressure difference between the feed side and the permeate side of the permeating substance, The unit is [mol·(m ² ·s·Pa) ⁻¹ ], and is a value calculated by the method described in the Examples section.

Also, the selectivity of a zeolite membrane is represented by an ideal separation factor and a separation factor. The ideal separation factor and the separation factor are indices of selectivity commonly used in membrane separation, and are values calculated by the method described in the Examples section.

For example, when carbon dioxide and methane are permeated at a temperature of 50° C. and a differential pressure of 0.1 MPa, the ideal separation factor is usually 10 or more, preferably 20 or more, more preferably 30 or more, still more preferably 40 or more, and particularly preferably is 50 or more. The upper limit of the ideal separation factor is the case where only carbon dioxide is completely permeated, and in that case the separation factor is infinite, but in practice the separation factor may be about 100,000 or less.

The separation factor is typically comparable to the ideal separation factor when the two components are mixed in a 1:1 molar ratio. For example, when a mixed gas of carbon dioxide and methane at a volume ratio of 1:1 is permeated at a temperature of 50° C. and a differential pressure of 0.1 MPa, it is usually 10 or more, preferably 20 or more, more preferably 20 or more, like the ideal separation factor. It is 30 or more, more preferably 40 or more, and particularly preferably 50 or more. The upper limit of the separation factor is the case where only carbon dioxide is completely permeated, and in that case the separation factor is infinite, but in practice, the separation factor may be about 100,000 or less.

As described above, the zeolite membrane composite of the present invention has excellent chemical resistance, oxidation resistance, heat stability, and pressure resistance, exhibits high permeation performance and separation performance, and has excellent durability. It can be particularly suitably used as the following gas separation technology.

Carbon dioxide separation technology includes removing carbon dioxide from natural gas, and separating landfill gas (approximately 60% methane, 40% carbon dioxide, containing trace amounts of nitrogen and water vapor) generated by landfilling organic matter such as household waste. carbon dioxide removal and the like.

Hydrogen separation technology includes hydrogen recovery in the petroleum refining industry, hydrogen recovery and refining (mixtures of hydrogen, carbon monoxide, carbon dioxide, hydrocarbons, etc.) in various reaction processes in the chemical industry, and production of high-purity hydrogen for fuel cells. and so on. Hydrogen production for fuel cells is obtained by the steam reforming reaction of methane, requiring the separation of hydrogen from a gas mixture of _H2 , CO, _CH4 , _H2O .

In addition, as oxygen separation technology, production of oxygen-enriched gas from air (medical use, oxygen-enriched air for combustion, etc.), production of nitrogen enriched gas from air (explosion-proof, anti-oxidation, etc.) as nitrogen separation technology ), water vapor separation (dehumidification of precision machinery, etc.), dissolved gas separation (water, degassing from organic liquids), organic gas separation (organic gas separation in petroleum refining industry, petrochemical industry, olefin, paraffin separation), etc. is mentioned.

Hereinafter, the present invention will be described in more detail based on experimental examples, but the present invention is not limited to the following experimental examples as long as the gist thereof is not exceeded. Various production conditions and values of evaluation results in the following Experimental Examples (Preparation Examples or Examples) have the meaning of preferred values for the upper limit or lower limit in the embodiments of the present invention, and the preferred range is The range may be defined by a combination of the upper limit or lower limit and the values in the following Experimental Examples (Preparation Examples or Examples) or values between Experimental Examples (Preparation Examples or Examples).

In the following experimental examples, the physical properties and separation performance of zeolite membranes were measured by the following methods unless otherwise specified.
(1) X-ray diffraction (XRD)
XRD measurement was performed under the following conditions.
・ Apparatus name: X'PertPro MPD manufactured by PANalytical in the Netherlands
・Optical system specifications Incident side: Sealed X-ray tube (CuKα)
Soller Slit (0.04rad)
Divergence Slit (Variable Slit)
Sample stand: 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): 45 kV, 40 mA
Scan axis: θ/2θ
Scanning range (2θ): 5.0-70.0°
Measurement mode: Continuous
Read width: 0.05°
Counting time: 99.7 sec
Automatic variable slit (Automatic-DS): 1 mm (irradiation width)
Lateral divergence mask: 10 mm (irradiation width)

The X-rays were applied in a direction perpendicular to the axial direction of the cylindrical tube. In addition, in order to avoid noise as much as possible, X-rays are used instead of the two lines where the cylindrical tubular membrane composite placed on the sample stage and the surface parallel to the surface of the sample stage are in contact with each other. , mainly on the other line above the surface of the sample stage.
In addition, the irradiation width was fixed at 1 mm by an automatic variable slit, and measured, and the variable slit → fixed slit conversion was performed using the XRD analysis software JADE 7.5.2 (Japanese version) of MaterialsData, Inc. was performed to obtain the XRD pattern.

(2) SEM-EDX
・Device name: SEM: FE-SEM Hitachi: S-4800
EDX: EDAX Genesis
・Acceleration voltage: 10 kV
X-ray quantitative analysis was performed by scanning the entire field of view (25 μm×18 μm) at a magnification of 5000 times.

(3) XPS measurement XPS (X-ray photoelectron spectroscopy) measurement of the zeolite membrane surface was performed under the following conditions.
・ Device name: Quantum 2000 manufactured by PHI
・X-ray source: monochromatic Al-Kα, output 16kV-34W (X-ray generation area 170μmφ)
・Electrification neutralization: electron gun (5 μA), ion gun (10 V) combined ・Spectroscopic system: pulse energy 187.85 eV @ wide spectrum
58.70 eV @ narrow spectrum (Na1s, Al2p, Si2p, K2p, S2p)
29.35 eV @ wide spectrum (C1s, O1s, Si2p)
・Measurement area: spot irradiation (irradiation area <340 μmφ)
・Extraction angle: 45° (from the surface)

(4) Air permeation amount Under atmospheric pressure, one end of the zeolite membrane composite is sealed, the other end is connected to a 5 kPa vacuum line while maintaining airtightness, and the vacuum line and the zeolite membrane composite are separated. The flow rate of the air that permeated the zeolite membrane composite was measured with a mass flow meter installed between them, and it was taken as the air permeation amount [L/(m ² ·h)]. As a mass flow meter, 8300 manufactured by KOFLOC, for N2 gas, with a maximum flow rate of 500 ml/min (20° C., converted to 1 atm) was used. When the mass flow meter display of KOFLOC 8300 is 10ml/min (20°C, 1 atmosphere conversion) or less, Lintec MM-2100M for Air gas, maximum flow rate 20ml/min (0°C, 1 atmosphere conversion) was measured using

(5) Single-component gas permeation test A single-component gas permeation test was performed using an apparatus schematically shown in Fig. 1 as follows. The sample gases used were carbon dioxide (purity 99.9%, manufactured by Koatsu Gas Kogyo Co., Ltd.), methane (purity 99.999%, manufactured by Japan Fine Products), hydrogen (purity 99.99% or higher, hydrogen manufactured by HORIBASTEC). generated from generator OPGU-2200), nitrogen (99.99% purity, manufactured by Toho Sanso Kogyo Co., Ltd.), and helium (99.99 purity, manufactured by Japan Helium Center Co., Ltd.).

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

One end of the cylindrical zeolite membrane composite 1 is sealed with a cylindrical endpin 3 . The other end is connected to the connecting portion 4 , and the other end of the connecting portion 4 is connected to the pressure vessel 2 . The inside of the cylindrical zeolite membrane composite and a pipe 11 for discharging the permeating gas 8 are connected via the connecting part 4 , and the pipe 11 extends to the outside of the pressure vessel 2 . A pressure gauge 5 for measuring the pressure on the supply side of the sample gas is connected to any point leading to the pressure vessel 2 . Each connection is airtightly connected.

In the apparatus of FIG. 1, when performing a single component gas permeation test, a sample gas (supply gas 7) is supplied between the pressure vessel 2 and the zeolite membrane composite 1 at a constant pressure, and the The permeated gas 8 thus obtained is measured by a flow meter (not shown) connected to the pipe 11 .

The gas permeation test can also be performed with the apparatus schematically shown in FIG. 2 as follows.
In FIG. 2, a cylindrical zeolite membrane composite 1 is placed in a constant temperature bath (not shown) while being housed in a pressure-resistant container 2 made of stainless steel. The constant temperature bath is equipped with a temperature controller so that the temperature of the sample gas can be adjusted.

One end of the cylindrical zeolite membrane composite 1 is sealed with a circular endpin 3 . The other end is connected to the connecting portion 4 , and the other end of the connecting portion 4 is connected to the pressure vessel 2 . The inside of the cylindrical zeolite membrane composite and a pipe 11 for discharging the permeating gas 8 are connected via the connecting portion 4 , and the pipe 11 extends to the outside of the pressure vessel 2 . A pipe 12 for supplying a sweep gas 9 is inserted in the zeolite membrane composite 1 via a pipe 11 . Further, a pressure gauge 5 for measuring the pressure on the supply side of the sample gas and a back pressure valve 6 for adjusting the pressure on the supply side are connected to any point leading to the pressure vessel 2 . Each connection is airtightly connected.

In the apparatus of FIG. 2, when performing a gas permeation test, a sample gas (supply gas 7) is supplied between the pressure vessel 2 and the zeolite membrane composite 1 at a constant flow rate, and the pressure on the supply side is is constant, the flow rate of the exhaust gas discharged from the pipe 11 is measured.

More specifically, in order to remove components such as moisture and air, after drying at a measurement temperature or higher and purging with exhaust or the supply gas used, the sample temperature and the supply gas of the zeolite membrane composite 1 After the differential pressure between the 7 side and the permeating gas 8 side is constant and the permeating gas flow rate is stabilized, the flow rate of the sample gas (permeating gas 8) that permeates the zeolite membrane composite 1 is measured, and the gas permeance [mol · (m ² ·s·Pa) ⁻¹ ]. The pressure difference (differential pressure) between the supply side and the permeate side of the supply gas is used as the pressure for calculating the permeance.

Based on the above measurement results, the ideal separation factor α is calculated by the following formula (1).
α=(Q1/Q2)/(P1/P2) (1)
[In formula (1), Q1 and Q2 represent the permeation amount [mol·(m ² ·s) ⁻¹ ] of a gas with high permeability and a gas with low permeability, respectively, and P1 and P2 are, respectively, The pressure [Pa] of the highly permeable gas and the less permeable gas as the supply gas is shown. ]

In the separation of the mixed gas, the separation factor α' is calculated by the following formula (2).
α'=(Q'1/Q'2)/(P'1/P'2) (2)
[In formula (2), Q′1 and Q′2 represent the permeation amount of a gas with high permeability and a gas with low permeability [mol·(m ² ·s) ⁻¹ ], and P′1 and P′2 indicate the pressure [Pa] of the highly permeable gas and the less permeable gas, respectively, which are the supply gases. ]

(Preparation Example 1)
An inorganic porous support-CHA-type zeolite membrane composite was produced by directly hydrothermally synthesizing a CHA-type aluminosilicate zeolite on an inorganic porous support.
A reaction mixture for hydrothermal synthesis was prepared as follows.
To 44.1 g of 1 mol/L-NaOH aqueous solution and 29.0 g of 1 mol/L-KOH aqueous solution, 2.52 g of aluminum hydroxide (containing 53.5% by mass of Al ₂ O ₃ , manufactured by Aldrich) was added, and 591 g of water was added. In addition, the mixture was stirred to dissolve the aluminum hydroxide. To this, 13.5 g of an aqueous solution of N,N,N-trimethyl-1-adamantane ammonium hydroxide (hereinafter referred to as "TMADAOH") (containing 25% by mass of TMADAOH, manufactured by Seichem) was added as an organic template, and further 60.0 g of colloidal silica (Snowtech-40 manufactured by Nissan Chemical Industries, Ltd.) was added and stirred for 2 hours to form an aqueous reaction mixture.

The composition (molar ratio) of this reaction mixture was SiO ₂ /Al ₂ O ₃ /NaOH/KOH/H ₂ O/TMADAOH=1/0.033/0.11/0.073/100/0.04, SiO ₂ /Al ₂ O ₃ =30.

As the inorganic porous support, a porous alumina tube (outer diameter: 12 mm, inner diameter: 9 mm) was cut into a length of 400 mm, and powder generated during the cutting was removed by compressed air.

Seed crystals were deposited on the support prior to hydrothermal synthesis. 160 with a gel composition of SiO ₂ /Al ₂ O ₃ /NaOH/KOH/H ₂ O/TMADAOH=1/0.033/0.1/0.06/40/0.07 by a method similar to the above method. CHA-type zeolite having a grain size of about 0.5 μm crystallized by hydrothermal synthesis at ℃ for 2 days was used as a seed crystal.

The seed crystals were dispersed in desalted water to a concentration of about 0.3% by mass, and the support was immersed for a predetermined time and then dried at 100° C. for 4 hours or more to attach the seed crystals.

Two supports with attached seed crystals were vertically immersed in a Teflon (registered trademark) inner cylinder (800 ml) containing the above aqueous reaction mixture, the autoclave was sealed, and the mixture was allowed to stand at 160° C. for 48 hours. It was heated under autogenous pressure while standing. After a predetermined period of time, the zeolite membrane composite was allowed to cool, then taken out from the reaction mixture, washed, and dried at 100° C. for 4 hours or more.

This membrane composite was cut into pieces of 200 mm each, and then fired in an electric furnace at 500° C. for 5 hours in the air. The average mass of CHA-type zeolite crystallized on the support obtained from the difference between the mass of the membrane composite after firing and the mass of the support was 196 g/m ² . Moreover, the air permeation amount after firing was 81 L/(m ² ·h).

FIG. 4 shows the XRD pattern of the produced zeolite membrane. * in the figure indicates a peak derived from the support. It was found from the XRD measurement that CHA-type zeolite was produced.
The XRD pattern of powdered CHA-type zeolite (zeolite commonly referred to as SSZ-13 in US Pat. No. 4,544,538, hereinafter referred to as "SSZ-13") is shown in FIG.

From FIG. 4, it can be seen that the XRD pattern of the produced zeolite membrane has a significantly higher peak intensity near 2θ=17.9° than the XRD pattern (FIG. 5) of SSZ-13, which is a powdered CHA-type zeolite. .
For SSZ-13, which is a powdered CHA-type zeolite, (intensity of peak near 2θ = 17.9°) / (intensity of peak near 2θ = 20.8°) = 0.2, the produced zeolite membrane (Peak intensity near 2θ = 17.9°)/(Peak intensity near 2θ = 20.8°) = 1.2. was done.

The SiO ₂ /Al ₂ O ₃ molar ratio of the zeolite membrane was 34 as measured by SEM-EDX.

(Example 1)
The membrane composite obtained in Preparation Example 1 was cut into 40 mm pieces, and Teflon (registered trademark) containing about 0.9 M iron nitrate aqueous solution in which 14.1 g of iron (III) nitrate nonahydrate was dissolved in 35 g of water. It was placed in an inner cylinder (100 ml). The autoclave was sealed and heated to 100° C. for 1 hour under static and autogenous pressure. After the lapse of a predetermined time, the zeolite membrane composite was allowed to cool, then removed from the aqueous solution, washed, and dried at 100° C. for 4 hours or more.

The Fe/Al molar ratio of the zeolite membrane surface measured by XPS was 0.17.

A single-component gas permeation test was performed using the above CHA-type zeolite membrane composite treated with an aqueous iron nitrate solution. Gases evaluated are carbon dioxide, methane, hydrogen, nitrogen and helium.

First, as a pretreatment, the zeolite membrane composite was introduced at 140 ° C. with CO ₂ as the feed gas 7 between the pressure vessel 2 and the cylinder of the zeolite membrane composite 1, and the pressure was reduced to about 0.16 MPa. The inside of the cylinder of the zeolite membrane composite 1 was kept at 0.098 MPa (atmospheric pressure) and dried for 70 minutes or more, and it was confirmed that the CO ₂ permeation amount did not change.

After that, the pressure on the supply side was set to 0.20 MPa, and the supply gas was changed to each evaluation gas. At this time, the differential pressure between the feed gas 7 side and the permeate gas 8 side of the zeolite membrane composite 1 was 0.1 MPa.

After that, the temperature was set to 50° C., and after the temperature was stabilized, the supplied gas was changed to each evaluation gas. At this time, the differential pressure between the feed gas 7 side and the permeate gas 8 side of the zeolite membrane composite 1 was 0.1 MPa.

Table 1 shows the permeance and separation factor of each gas at 50°C, and Table 2 shows the permeance and separation factor of each gas at 140°C.

(Example 1: Permeation test example)
A single-component gas permeation test was performed in the same manner as in Example 1, except that the membrane composite obtained in Preparation Example 1 was cut into 40 mm pieces and used without being treated with an aqueous iron nitrate solution. Table 1 shows the obtained permeance and separation factor of each gas at 50°C, and Table 2 shows the permeance and separation factor of each gas at 140°C.

As shown in Tables 1 and 2, it was confirmed that the treatment with the iron nitrate aqueous solution sufficiently increased the separation factors of CO ₂ /CH ₄ , H ₂ /CH ₄ and CO ₂ /N ₂ .

(Preparation Example 2)
An inorganic porous support-CHA-type zeolite membrane composite was produced by directly hydrothermally synthesizing a CHA-type aluminosilicate zeolite on an inorganic porous support.
A reaction mixture for hydrothermal synthesis was prepared as follows.
0.306 g of aluminum hydroxide (containing 53.5% by mass of Al ₂ O ₃ , manufactured by Aldrich) was added to a mixture of 12.0 g of 1 mol/L aqueous NaOH solution, 8.0 g of 1 mol/L aqueous KOH solution, and 115 g of water. It was added and dissolved by stirring to obtain a clear solution. To this, 2.7 g of an aqueous solution of N,N,N-trimethyl-1-adamantane ammonium hydroxide (hereinafter referred to as "TMADAOH") (containing 25% by mass of TMADAOH, manufactured by Seichem) was added as an organic template, and further 12.0 g of colloidal silica (Snowtech-40 manufactured by Nissan Chemical Industries, Ltd.) was added and stirred for 2 hours to form an aqueous reaction mixture.

The composition (molar ratio) of this reaction mixture was SiO ₂ /Al ₂ O ₃ /NaOH/KOH/H ₂ O/TMADAOH=1/0.01/0.15/0.1/100/0.04, SiO ₂ /Al ₂ O ₃ =100.

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

As seed crystals, a gel composition (molar ratio) of SiO ₂ /Al ₂ O ₃ /NaOH/KOH/H ₂ O/TMADAOH = 1/0.066/0.15/0.1/100/0.04, A CHA-type zeolite was used which was obtained by filtering, washing and drying a precipitate produced by hydrothermal synthesis at 160° C. for 2 days in the presence of a porous alumina tube (outer diameter 12 mm, inner diameter 9 mm). The grain size of the seed crystal was about 2 to 4 μm.

The seed crystals were dispersed in an alkaline aqueous solution containing 0.33% by mass of NaOH and 0.31% by mass of KOH to a concentration of about 1% by mass. It was dried and seed crystals were attached. The weight gain after drying was 9.9 g/m ² .

The support to which the seed crystals were attached was vertically immersed in a Teflon (registered trademark) inner cylinder (200 ml) containing the above aqueous reaction mixture, the autoclave was sealed, and the mixture was allowed to stand at 160°C for 48 hours. and heated under autogenous pressure. After a predetermined period of time, the support-zeolite membrane composite was allowed to cool, then removed from the reaction mixture, washed, and dried at 100° C. for 4 hours or longer.

This membrane composite was calcined in air in an electric furnace at 500° C. for 10 hours. At this time, both the rate of temperature increase and the rate of temperature decrease were set to 0.5° C./min. The mass of the CHA-type zeolite crystallized on the support was 122 g/m ² , which was calculated from the difference between the mass of the membrane composite after sintering and the mass of the support. Moreover, the air permeation amount after firing was 570 L/(m ² ·h).

FIG. 6 shows the XRD pattern of the produced zeolite membrane. * in the figure indicates a peak derived from the support. It was found from the XRD measurement that CHA-type zeolite was produced. Also, (intensity of peak near 2θ = 9.6°)/(intensity of peak near 2θ = 20.8°) = 3.4, (intensity of peak near 2θ = 17.9°)/(2θ = The intensity of the peak near 20.8°) was 0.34. Compared with the XRD pattern of the powdered CHA-type zeolite in FIG. ) are about the same, while (intensity of the peak near 2θ = 9.6°)/(intensity of the peak near 2θ = 20.8°) is higher. 0,0) orientation was assumed.

The SiO ₂ /Al ₂ O ₃ molar ratio of the zeolite membrane measured by SEM-EDX was 40.2.

(Example 2)
The membrane composite obtained in Preparation Example 2 was cut to 30 mm, and a 0.2 M iron nitrate solution containing 2.12 g of iron (III) nitrate nonahydrate dissolved in 25 g of water was placed in a Teflon (registered trademark) It was placed in an inner cylinder (100 ml). The autoclave was sealed and heated to 100° C. for 1 hour under static and autogenous pressure. After a predetermined time had elapsed, the support-zeolite membrane composite was allowed to cool, then removed from the aqueous solution, washed, and dried at 100° C. for 4 hours or more.

Then, in the same manner as in Example 1, a single-component gas permeation test was performed. Table 3 shows the obtained permeance and separation factor of each gas at 50°C, and Table 4 shows the permeance and separation factor of each gas at 140°C.

(Example 2: Permeation test example)
A single-component gas permeation test was performed in the same manner as in Example 1, except that the membrane composite obtained in Preparation Example 2 was cut into 40 mm pieces and used without being treated with an aqueous iron nitrate solution. Table 3 shows the obtained permeance and separation factor of each gas at 50°C, and Table 4 shows the permeance and separation factor of each gas at 140°C.

As shown in Tables 3 and 4, it was confirmed that even a zeolite membrane composite with a low aluminum content, such as a SiO ₂ /Al ₂ O ₃ molar ratio of 40.2, was sufficiently increased in separation factor by treatment with an aqueous iron nitrate solution. .

(Preparation Example 3)
An inorganic porous support-CHA-type zeolite membrane composite was produced by directly hydrothermally synthesizing a CHA-type aluminosilicate zeolite on an inorganic porous support.
A reaction mixture for hydrothermal synthesis was prepared as follows.
To 60.1 g of 1 mol/L-NaOH aqueous solution and 40.0 g of 1 mol/L-KOH aqueous solution, 5.03 g of aluminum hydroxide (containing 53.5% by mass of Al ₂ O ₃ , manufactured by Aldrich) was added, and further 574 g of water was added. In addition, the mixture was stirred to dissolve the aluminum hydroxide. To this, 13.5 g of an aqueous solution of N,N,N-trimethyl-1-adamantane ammonium hydroxide (hereinafter referred to as "TMADAOH") (containing 25% by mass of TMADAOH, manufactured by Seichem) was added as an organic template, and further 60.1 g of colloidal silica (Snowtech-40 manufactured by Nissan Chemical Industries, Ltd.) was added and stirred for 2 hours to form an aqueous reaction mixture.

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

The average mass of CHA-type zeolite crystallized on the support obtained from the difference between the mass of the membrane composite after firing and the mass of the support was 116 g/m ² . Moreover, the air permeation amount after firing was 120 L/(m ² ·h).

The XRD pattern of the produced zeolite membrane is shown in FIG. * in the figure indicates a peak derived from the support. It was found from the XRD measurement that CHA-type zeolite was produced.
From FIG. 7, it can be seen that the XRD pattern of the produced zeolite membrane has a significantly higher peak intensity near 2θ=17.9° compared to the XRD pattern (FIG. 5) of SSZ-13, which is a powdered CHA-type zeolite. .

For SSZ-13, which is a powdered CHA-type zeolite, (intensity of peak near 2θ = 9.6°) / (intensity of peak near 2θ = 20.8°) = 5.7, the resulting zeolite membrane (Intensity of peak near 2θ = 17.9°)/(Intensity of peak near 2θ = 20.8°) = 6.4. , 1) orientation to the plane was inferred.

(Example 3)
The membrane composite obtained in Preparation Example 3 was cut to 40 mm, and an inner cylinder made of Teflon (registered trademark) was filled with an approximately 1 M lanthanum nitrate aqueous solution in which 15.2 g of lanthanum nitrate hexahydrate was dissolved in 31.2 g of water. (100 ml). The autoclave was sealed and heated to 100° C. for 1 hour under static and autogenous pressure. After the lapse of a predetermined time, the zeolite membrane composite was allowed to cool, then removed from the aqueous solution, washed, and dried at 100° C. for 4 hours or longer.

Then, in the same manner as in Example 1, a single-component gas permeation test was conducted. Table 5 shows the obtained permeance and separation factor of each gas at 50°C, and Table 6 shows the permeance and separation factor of each gas at 140°C.

(Example 4)
The membrane composite obtained in Preparation Example 3 was cut to 40 mm, and an inner cylinder made of Teflon (registered trademark) was filled with an approximately 1 M chromium nitrate aqueous solution in which 14.0 g of chromium nitrate nonahydrate was dissolved in 29.3 g of water. (100 ml). The autoclave was sealed and heated to 100° C. for 1 hour under static and autogenous pressure. After the lapse of a predetermined time, the zeolite membrane composite was allowed to cool, then removed from the aqueous solution, washed, and dried at 100° C. for 4 hours or longer.

Then, in the same manner as in Example 1, a single-component gas permeation test was performed. Table 5 shows the obtained permeance and separation factor of each gas at 50°C, and Table 6 shows the permeance and separation factor of each gas at 140°C.

(Example 5)
The membrane composite obtained in Preparation Example 3 was cut to 40 mm, and an inner cylinder made of Teflon (registered trademark) was filled with an approximately 1 M zirconyl nitrate aqueous solution in which 9.6 g of zirconyl nitrate dihydrate was dissolved in 33.9 g of water. (100 ml). The autoclave was sealed and heated to 100° C. for 1 hour under static and autogenous pressure. After the lapse of a predetermined time, the zeolite membrane composite was allowed to cool, then removed from the aqueous solution, washed, and dried at 100° C. for 4 hours or longer.

Then, in the same manner as in Example 1, a single-component gas permeation test was conducted. Table 5 shows the obtained permeance and separation factor of each gas at 50°C, and Table 6 shows the permeance and separation factor of each gas at 140°C.

(Example 6)
The membrane composite obtained in Preparation Example 3 was cut into 40 mm pieces, and an inner cylinder made of Teflon (registered trademark) containing about 1 M magnesium nitrate aqueous solution in which 8.9 g of magnesium nitrate hexahydrate was dissolved in 31.2 g of water. (100 ml). The autoclave was sealed and heated to 100° C. for 1 hour under static and autogenous pressure. After the lapse of a predetermined time, the zeolite membrane composite was allowed to cool, then removed from the aqueous solution, washed, and dried at 100° C. for 4 hours or more.

Then, in the same manner as in Example 1, a single-component gas permeation test was conducted. Table 5 shows the obtained permeance and separation factor of each gas at 50°C, and Table 6 shows the permeance and separation factor of each gas at 140°C.

(Example 7)
The membrane composite obtained in Preparation Example 3 was cut to 40 mm, and an inner cylinder made of Teflon (registered trademark) was filled with an approximately 1 M gallium nitrate aqueous solution in which 14.0 g of gallium nitrate octahydrate was dissolved in 30.0 g of water. (100 ml). The autoclave was sealed and heated to 100° C. for 1 hour under static and autogenous pressure. After the lapse of a predetermined time, the zeolite membrane composite was allowed to cool, then removed from the aqueous solution, washed, and dried at 100° C. for 4 hours or longer.

Then, in the same manner as in Example 1, a single-component gas permeation test was conducted. Table 5 shows the obtained permeance and separation factor of each gas at 50°C, and Table 6 shows the permeance and separation factor of each gas at 140°C.

(Example 8)
The film treated with about 1 M lanthanum nitrate aqueous solution obtained in Example 3 was washed, dried and then calcined at 300° C. for 4 hours.

Then, in the same manner as in Example 1, a single-component gas permeation test was conducted. Table 5 shows the obtained permeance and separation factor of each gas at 50°C, and Table 6 shows the permeance and separation factor of each gas at 140°C.

(Example 9)
The film treated with about 1 M magnesium nitrate aqueous solution obtained in Example 6 was washed, dried and then calcined at 300° C. for 4 hours.

Then, in the same manner as in Example 1, a single-component gas permeation test was performed. Table 5 shows the obtained permeance and separation factor of each gas at 50°C, and Table 6 shows the permeance and separation factor of each gas at 140°C.

(Example 10)
The film treated with about 1 M gallium nitrate aqueous solution obtained in Example 7 was washed, dried and then calcined at 300° C. for 4 hours.

Then, in the same manner as in Example 1, a single-component gas permeation test was performed. Table 5 shows the obtained permeance and separation factor of each gas at 50°C, and Table 6 shows the permeance and separation factor of each gas at 140°C.

(Example 3: Permeation test example)
A single-component gas permeation test was performed in the same manner as in Example 1, except that the membrane composite obtained in Preparation Example 3 was cut into 40 mm pieces and used without being treated with an aqueous metal nitrate solution. Table 5 shows the obtained permeance and separation factor of each gas at 50°C, and Table 6 shows the permeance and separation factor of each gas at 140°C.

INDUSTRIAL APPLICABILITY The present invention can be used in any industrial field, for example, chemical industry plants, natural gas refining plants, plants that generate biogas from garbage, etc., where separation of gas mixtures (gases) is required. particularly suitable in fields where it is necessary to separate water from hydrous organic compounds and recover organic compounds, such as chemical industry plants, fermentation plants, precision electronic parts factories, battery manufacturing factories, etc. can be used.

1: Zeolite membrane composite 2: Pressure vessel 3: End pin 4: Connection part 5: Pressure gauge 6: Back pressure valve 7: Supply gas 8: Permeated gas 9: Sweep gas 10: Exhaust gas 11: Permeated gas discharge pipe 12: Sweep gas introduction pipe 13: Liquid to be separated 14: Liquid sending pump 15: Vaporizer 16: Thermostatic bath 17: Zeolite membrane composite module 18: Trap for collecting liquid to be separated 19: Trap for collecting permeated liquid 20: Cold trap 21: Vacuum pump

Claims (7)

A method for producing a porous support-zeolite membrane composite having a zeolite membrane containing a divalent or higher metal excluding Al on an inorganic porous support,
The inorganic porous support is a ceramic sintered body,
The zeolite constituting the zeolite membrane is a CHA-type aluminosilicate,
forming the zeolite membrane having an air permeation rate of 1300 L/(m ² ·h) or less on an inorganic porous support; of metals,
immersing a zeolite membrane (membrane composite) formed on an inorganic porous support in a solution having a metal element source compound concentration of 0.05 to 3 mol/L;
spraying the solution onto the membrane composite;
Alternatively, a method for producing a metal-containing porous support-zeolite membrane composite, characterized in that the solution is added dropwise to the membrane composite. The method for producing a metal-containing porous support-zeolite membrane composite according to claim 1, wherein the membrane composite is immersed in the solution at 0 to 180°C. 3. The metal-containing porous porous material according to claim 1 or 2, wherein the zeolite membrane is formed by crystallizing zeolite on an inorganic porous support by hydrothermal synthesis using an aqueous reaction mixture containing an organic template. A method for producing a support-zeolite membrane composite. The method for producing a porous support-zeolite membrane composite according to any one of claims 1 to 3, wherein the inorganic porous support has an average pore size of 20 µm or less. The method for producing a porous support-zeolite membrane composite according to any one of claims 1 to 4, wherein the inorganic porous support has an average pore size of 0.02 µm or more. The method for producing a porous support-zeolite membrane composite according to any one of claims 1 to 5, which is for gas mixture separation. The method for producing a metal-containing porous support-zeolite membrane composite according to any one of claims 1 to 6, wherein the porous support-zeolite membrane composite is used for separation of carbon dioxide and methane.

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