JP2011041900A - Oxygen separation membrane module, method for producing the same and sealing material for oxygen separation membrane module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an oxygen separation membrane module in which a sealed part (joint part), that has high heat resistance even at high temperature (for example 1,200-1,300°C) equal to or higher than an operating temperature range of the oxygen separation membrane module and that is airtightly joined, is formed. <P>SOLUTION: The oxygen separation membrane module 100 includes: an oxygen separation membrane element 10 having an oxygen separation membrane 14 on a porous base material 12; and connection members (gas pipes 20, 30) made of ceramic. In joint portions of the oxygen separation membrane element 10 to gas pipes 20, 30, the sealed parts 40 for shutting off gas circulation in the joint portions are formed from a glass having at least a forsterite crystal precipitated in the glass matrix, or a glass having at least one selected from a MgO crystal, a cristobalite crystal, a leucite crystal and the forsterite crystal, precipitated in the glass matrix. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an oxygen separation membrane module (oxygen separation device) including an oxygen separation membrane element and a connection member. Specifically, a module having an oxygen separation membrane element including an oxygen separation membrane made of oxygen ion conductive oxide ceramics and a connecting member (for example, a gas pipe for supplying gas to the element) as basic components, and the above A method of manufacturing the module by joining an oxygen separation membrane element and a connecting member, and a sealing material (joining material) for forming a seal part (joining part) having airtightness between the element and the connecting member About.

As an oxygen ion conductor having oxygen ions (typically also called O ²⁻ ; oxide ions), oxide ceramics having a so-called perovskite structure are known. In particular, in addition to being an oxygen ion conductor, a dense ceramic material made of a perovskite oxide that is an oxygen ion-electron mixed conductor (hereinafter simply referred to as “mixed conductor”) having both electron conductivity, Typically, a ceramic material formed in a film shape can continuously transmit oxygen ions from one surface to the other surface without using an external electrode or an external circuit for short-circuiting both surfaces thereof. For this reason, as described in Patent Documents 1 to 3, particularly as an oxygen separation membrane material that selectively permeates oxygen from an oxygen-containing gas (for example, air) supplied to one surface to the other surface, the operating temperature Can be suitably used in a high temperature range of 800 ° C. or higher and lower than 1000 ° C.

For example, an oxygen separation membrane composed of a mixed conductor such as a perovskite oxide is formed on a porous substrate (porous support) and used as an oxygen separation membrane element. It can be suitably used as an effective oxygen purification means to replace the Pressure Swing Adsorption) method. In addition, the oxygen separation membrane element having such a structure is an oxidation reaction device for separating oxygen-containing gas (air) and hydrocarbon gas and selectively permeating oxygen to perform partial oxidation reaction of hydrocarbon, so-called diaphragm. It can be suitably used as a component of the reactor. That is, when an oxygen-containing gas is brought into contact with the surface on one side of the oxygen separation membrane and a hydrocarbon gas (for example, methane) is brought into contact with the surface on the other side, oxygen ions that are supplied through the oxygen separation membrane from one surface are supplied. The hydrocarbon is partially oxidized on the other side. Thus, the technique of partially oxidizing hydrocarbons using an oxygen separation membrane is suitably used in the GTL (Gas To Liquid) technique for producing a synthetic liquid fuel (such as methanol) or the fuel cell field.
As this type of prior art, Patent Documents 1 to 4 describe some perovskite oxides that are mixed conductors. Patent Documents 5 to 9 disclose examples of an oxygen separator (membrane element) including an oxygen separation membrane composed of a perovskite oxide. Patent Documents 10 to 11 describe a cylindrical oxygen separator (element) and a device (module) including the oxygen separator.

By the way, when constructing an oxygen separation device (module) using a cylindrical or other shape oxygen separation material (membrane element) as a basic component, various members are joined together. It is constructed in a form with a sealing part (joining part) to be held.
Conventionally, in an oxygen separation device (module) used in a high temperature range where the operating temperature is 800 ° C. or higher and lower than 1000 ° C., the sealing portion (joining portion) is required to ensure the sealing property (air tightness) of the sealing portion. A glass material or a metal material has been studied as a sealing material constituting the glass. For example, Patent Documents 12 to 13 describe examples of conventional sealing materials. Although not directly related to the present invention, for example, Patent Documents 14 to 18 describe a sealing material for a solid oxide fuel cell. Examples of such a sealing material include a solid electrolyte constituent material and a separator. Bonding material obtained by mixing constituent materials, sealing material in which filler materials such as MgO-MgAl ₂ O ₄ and stabilized zirconia are dispersed in a glass matrix, or glass containing silicon as a constituent element A sealing material made of a mixed powder obtained by mixing powder, magnesium oxide powder, and magnesium silicate powder has been proposed.

JP 2000-251534 A JP 2000-251535 A Special Table 2000-511507 JP 2001-93325 A International Publication No. WO2003 / 040058 Pamphlet JP 2006-82040 A JP 2007-51032 A JP 2007-51034 A JP 2007-51035 A JP-A-11-70314 JP 2002-292234 A JP 2002-83517 A JP 2002-349714 A JP-A-5-330935 JP-A-9-129251 Japanese Patent Laid-Open No. 11-154525 JP 2000-235862 A JP 2007-149430 A

The sealing material described in the above patent document is a material that can be in a molten state in the high temperature range (for example, see Patent Document 13), and melts when used in the high temperature range (for example, 800 ° C. or higher and lower than 1000 ° C.). There is a risk that it will flow out of a predetermined joining site. For this reason, it has been necessary to take structural measures to prevent the sealing material from flowing out (for example, adding a barrier structure that surrounds the molten sealing material or a structure that applies a load that prevents the sealing material from flowing out).
Further, a conventional glass material (for example, heat) that is difficult to thermally expand relative to a perovskite oxide (for example, a thermal expansion coefficient of 10 × 10 ⁻⁶ K ⁻¹ to 15 × 10 ⁻⁶ K ⁻¹ ) that is relatively easily thermally expanded. When a general borosilicate glass having an expansion coefficient of 1 × 10 ⁻⁶ K ^{−1 to} 5 × 10 ⁻⁶ K ⁻¹ ) is applied as a sealing material, the sealing material is caused by a difference in thermal expansion at the time of low-temperature solidification. There is a risk of damage. Furthermore, when the oxygen separation material obtained by adopting a conventional sealing material having a large difference in thermal expansion is repeatedly used in the above high temperature range, the sealing performance of the seal part is increased at the time of temperature increase before use and at the time of temperature decrease after use. There is also a possibility of a gradual decrease, and there is room for improvement from the viewpoint of durability.

In recent years, for the production of oxygen separation membrane modules, for the purpose of improving the efficiency of manufacturing processes and reducing costs, for example, formation of oxygen separation membranes of oxygen separation membrane elements, and members connected to the elements and the elements ( It has been studied to perform joint (stacking) with a connecting member, such as a gas pipe, at the same time (that is, fire simultaneously) in a single firing step. In order to realize such simultaneous firing, a highly heat-resistant bonding material that does not cause elution even when exposed to the firing temperature of the oxygen separation membrane (for example, 1200 to 1300 ° C., more preferably 1200 to 1400 ° C.) is necessary. is there.
Therefore, the oxygen separation membrane element and the connection object to be joined under a higher temperature condition (for example, 1200 to 1400 ° C. which is the firing temperature of the oxygen separation membrane) than the high temperature range (for example, 800 ° C. or more and less than 1000 ° C.) A seal part (joint part) that can have a coefficient of thermal expansion similar to that of a member, and can realize a high level of strength (heat resistance) and airtightness (sealability) that can sufficiently withstand the high temperature atmosphere. There has been a demand for a sealing material (bonding material) capable of forming the portion.
However, conventional sealing materials (joining materials) as described in the above-mentioned patent documents are still not sufficient in terms of achieving both high heat resistance and high airtightness.

  The present invention has been made in view of the above points, and its main purpose is to use the oxygen separation membrane module in a temperature range (for example, 800 ° C. or higher and lower than 1000 ° C.) or higher (typically 1000 ° C. or higher, particularly To provide an oxygen separation membrane module in which a seal part (joint part) having high heat resistance and hermetically joined is formed even at a high temperature of 1200 ° C. or higher, for example, 1200 to 1300 ° C. Further, a sealing material used for forming a seal portion (joint portion) having such a high heat resistance and high airtightness and having a thermal expansion coefficient comparable to that of the object to be joined is provided. The other purpose is to provide. Furthermore, it is another object to provide a method for producing an oxygen separation membrane module using such a sealing material.

In order to achieve the above object, an oxygen separation membrane module according to one aspect provided by the present invention comprises an oxygen separation membrane comprising an oxygen separation membrane made of an oxide ceramic having a perovskite structure, which is an oxygen ion conductor, on a porous substrate. A membrane element and a ceramic connecting member joined to the oxygen separation membrane element are provided (as main components). A seal portion that blocks gas flow in the joint portion (that is, maintains airtightness in the joint portion) is formed at a joint portion between the oxygen separation membrane element and the connection member. It is formed of glass in which at least forsterite crystals are precipitated in the glass matrix. The glass comprises the following six constituent elements (essential constituent elements Si, Al, Na, K and optional constituent elements Ca, B), and the entire six constituent elements in terms of oxides. The following mass composition as 100% by mass:
SiO ₂ 60 to 78 wt%;
Al ₂ O ₃ 10~22% by weight;
Na ₂ O 3-16% by mass;
K ₂ O 5-16% by mass;
CaO 0 to 4% by mass;
B ₂ O _{30 to} 4% by mass;
Have. Here, the glass further has Mg as a constituent element, and the mass composition of MgO is 1% by mass or more and less than 13% by mass with respect to 100% by mass of the whole glass in terms of oxide (MgO conversion), At least half of this amount is present as a constituent of crystals precipitated in the glass matrix.
In the description of the technical scope of the present invention, the numerical range using “to” is a range including the left and right numerical values of “to” (that is, the numerical range “A to B” is not less than A and not more than B). ).

In the oxygen separation membrane module according to this aspect, an oxygen separation membrane element (typically a porous substrate and / or an oxygen separation membrane in the membrane element) and a connecting member (for example, for supplying gas to the oxygen separation membrane) Glass composition in which at least a forsterite (Mg ₂ SiO ₄ ) crystal is precipitated in a glass matrix (for example, a fine crystal of the forsterite is precipitated in a dispersed state in the glass matrix). , Hereinafter referred to as “crystal-containing glass”). When the crystal-containing glass constituting the seal portion contains the crystal component as described above, the oxygen separation membrane module is used in a temperature range (for example, 800 ° C. or higher and lower than 1000 ° C.) or higher (typically 1000 ° C.). In particular, even when exposed to a high temperature range of 1200 ° C. or higher, for example, 1200 to 1300 ° C., more preferably 1200 to 1400 ° C., dissolution of crystals precipitated in the crystal-containing glass is preferably prevented, It is difficult to flow. Therefore, according to the oxygen separation membrane module according to the present aspect, there is no possibility that the seal portion between the oxygen separation membrane element and the connection member formed of the crystal-containing glass is eluted even when reaching the high temperature range as described above. Thus, the heat resistance of the seal part can be improved.
The crystal-containing glass has flexibility even in the temperature range. As a result, even when a stress is generated in the seal portion formed of the crystal-containing glass, the stress is relaxed to prevent the occurrence of cracks and peeling, and the mechanical strength of the seal portion is reduced. Improvements can be realized. Therefore, according to the oxygen separation membrane module according to this aspect, a high-performance oxygen separation membrane module having high heat resistance and durability (mechanical strength) is provided.

In addition, the seal portion formed by the crystal-containing glass having the mass composition as described above includes an oxygen separation membrane element and a connection member (or a joined body of the oxygen separation membrane element and the connection member) sealed (joined) by the seal portion. It may have a thermal expansion coefficient that approximates the thermal expansion coefficient (thermal expansion coefficient) of the whole. For this reason, in the oxygen separation membrane module provided with such a seal portion, the above operating temperature range (for example, 800 ° C. or higher and lower than 1000 ° C., and further includes a high temperature range, for example, 1000 to 1200 ° C.) and the temperature when not in use (normal temperature) ) And repeatedly using the temperature rise and fall, or when subjected to a treatment exposed to a high temperature above the use temperature range (for example, baking of an oxygen separation membrane), Gas leakage is prevented, and high airtightness and mechanical strength can be maintained over a long period of time. Further, the performance of the oxygen separation membrane module can be improved by preventing gas leakage.
Further, forsterite crystals precipitated in the glass matrix, or crystals that can be precipitated in the glass matrix together with the forsterite crystals, for example, cristobalite (SiO ₂ ) crystals, leucite (KAlSi ₂ O ₆ ) crystals, etc. In addition, since it is an insulator having neither ionic conductivity nor conductivity, a glass having a suitable aspect as the crystal-containing glass can have complete insulation. Thus, according to the oxygen separation membrane module of this aspect, formation of an insulating seal part can be realized, and ion conduction and electron conduction through the seal part can be avoided.
In the present specification, the “membrane” is not limited to a specific thickness, and in the oxygen separation membrane element, at least a membrane-like or layer-like portion that functions as an “oxygen ion conductor (preferably a mixed conductor)” Say.

According to another aspect of the oxygen separation membrane module provided by the present invention, an oxygen separation membrane element including an oxygen separation membrane made of an oxide ceramic having a perovskite structure, which is an oxygen ion conductor, on a porous substrate; And a ceramic connection member joined to the separation membrane element. A seal portion that blocks gas flow at the joint portion is formed at the joint portion between the oxygen separation membrane element and the connection member. The seal portion is formed of glass in which a crystal made of magnesium oxide (MgO) and at least one crystal selected from a cristobalite crystal, a leucite crystal, and a forsterite crystal are precipitated in a glass matrix. . The glass contains the following six constituent elements (essential constituent elements Si, Al, Na, K and optional constituent elements Ca, B), and 100 masses of the total of the six constituent elements in terms of oxides. The following mass composition as%:
SiO ₂ 60 to 78 wt%;
Al ₂ O ₃ 10~22% by weight;
Na ₂ O 3-16% by mass;
K ₂ O 5-16% by mass;
CaO 0 to 4% by mass;
B ₂ O _{30 to} 4% by mass;
Have. Here, the glass further has Mg as a constituent element, and the total composition of the glass is 100% by mass in terms of oxide, and the mass composition of MgO is 13% by mass to 30% by mass. Half of the amount is present as a constituent of the crystals precipitated in the glass matrix.
In the oxygen separation membrane module according to this aspect, an oxygen separation membrane element (typically a porous substrate and / or an oxygen separation membrane in the membrane element) and a connecting member (for example, supplying gas to the oxygen separation membrane element). In addition to crystals made of MgO in the glass matrix, at least one of cristobalite crystals, leucite crystals, and forsterite crystals is precipitated (for example, the above in the glass matrix) It is sealed with a sealing material comprising a glass composition in which various fine crystals are precipitated in a dispersed state (hereinafter sometimes referred to as “crystal-containing glass”). When the crystal-containing glass constituting the sealing material contains the crystal component as described above, the oxygen separation membrane module can be used in a temperature range (for example, 800 ° C. or higher and lower than 1000 ° C.) or higher (typically 1000 ° C.). As described above, even if the sealing part of the module is exposed to a high temperature range of, for example, 1200 to 1300 ° C., more preferably 1200 to 1400 ° C., dissolution of crystals precipitated in the bonding material is preferably prevented, and It is hard to do. Moreover, since the said crystal | crystallization including MgO crystal | crystallization is an insulator which has neither ionic conductivity nor electroconductivity, the said crystal | crystallization containing glass has perfect insulation. Furthermore, the seal part formed by the crystal-containing glass having the mass composition as described above has a thermal expansion coefficient approximate to the thermal expansion coefficient (thermal expansion coefficient) of the oxygen separation membrane element and the gas pipe sealed by the seal part. Can have.
Therefore, according to the oxygen separation membrane module according to the present aspect, there is no possibility that the seal portion formed using the sealing material made of the crystal-containing glass elutes even when reaching the high temperature range as described above. Providing a high-performance oxygen separation membrane module with a seal part that has insulating properties while preventing cracks and peeling in the seal part and preventing gas leaks, improving heat resistance and mechanical strength Is done.

In a more preferable aspect of the oxygen separation membrane module disclosed herein, the glass constituting the seal portion is 10 × 10 ⁻⁶ K ^{−1 to} 14 × 10 ⁻ even after being exposed to a temperature of at least 1200 ° C. maintaining a thermal expansion coefficient of ⁶ K ^-1.
Such a coefficient of thermal expansion (typically, an average value between room temperature (25 ° C.) and 500 ° C. based on a general differential expansion method (TMA)) is suitable as a material for connecting members (for example, gas pipes), for example. Thermal expansion coefficient of zirconia-based oxides (zirconia-based materials) such as YSZ that can be used, perovskite-type oxides that can be suitably used as oxygen separation membrane materials, or magnesium oxide (MgO) that can be used as a porous substrate And approximate. The thermal expansion coefficient can be approximated to the thermal expansion coefficient of the entire oxygen separation membrane element or the entire oxygen separation membrane module including the oxygen separation membrane element and the connecting member. Therefore, according to the oxygen separation membrane module having such a configuration, even after being exposed to a high temperature range of at least 1200 ° C. (typically higher), it has the above thermal expansion coefficient and has high airtightness and mechanical strength. Formation of a seal (joining) portion that can be maintained in a dimension can be realized, and a high-performance oxygen separation membrane module having high heat resistance and durability can be realized.

In another preferable aspect of the oxygen separation membrane module disclosed herein, the oxygen separation membrane is an oxide having a perovskite structure having a composition represented by the general formula (1): Ln _1-x A _x MO _3-δ It is composed of ceramics. However, Ln in a formula is at least 1 sort (s) selected from a lanthanoid, A is at least 1 sort (s) selected from the group which consists of Sr, Ca, and Ba, M is 1 type which can comprise a perovskite type structure. Alternatively, two or more metal elements, 0 ≦ x <1, and δ is a value determined to satisfy the charge neutrality condition. The gas pipe is made of stabilized zirconia.
In the oxygen separation membrane module having such a configuration, the thermal expansion coefficient of the oxygen separation membrane and the joining member that can be joined (sealed), and the thermal expansion of the seal portion existing at the joined portion between the oxygen separation membrane and the connecting member. The coefficients are particularly well approximate. Therefore, according to the oxygen separation membrane module having such a configuration, an oxygen separation membrane module having high heat resistance and durability that can withstand repeated use in a high temperature range of, for example, about 1200 ° C. and can maintain hermeticity for a long period of time is realized. be able to.

As another aspect, the present invention provides a sealing material used for forming the sealing portion of the oxygen separation membrane module as described above. That is, the sealing material according to one aspect provided by the present invention includes an oxygen separation membrane element including an oxygen separation membrane made of an oxide ceramic having a perovskite structure which is an oxygen ion conductor on a porous substrate, and the oxygen separation membrane. A sealing material (joining material) for sealing and joining the oxygen separation membrane element and the connecting member in an oxygen separation membrane module comprising a ceramic connecting member (for example, a gas pipe) joined to the element. This sealing material has the following six constituent elements, the following six mass elements being 100% by mass as a whole in terms of oxides:
SiO ₂ 60 to 78 wt%;
Al ₂ O ₃ 10~22% by weight;
Na ₂ O 3-16% by mass;
K ₂ O 5-16% by mass;
CaO 0 to 4% by mass;
B ₂ O _{30 to} 4% by mass;
The glass mainly comprises glass having at least forsterite crystals precipitated in the glass matrix. Here, the glass further contains Mg as a constituent element, and the mass composition of MgO is 1% by mass or more and less than 13% by mass with respect to 100% by mass of the whole glass in terms of oxide, and at least of these Half of the amount is present as a constituent of crystals precipitated in the glass matrix.
By using the sealing material which concerns on this aspect, the oxygen separation membrane module in which the sealing part (joining part) excellent in heat resistance and durability as mentioned above was formed can be provided.

Another aspect of the sealing material provided by the present invention is an oxygen separation membrane element including an oxygen separation membrane made of an oxide ceramic having a perovskite structure, which is an oxygen ion conductor, on a porous substrate, and the oxygen separation A sealing material for sealing and joining the oxygen separation membrane element and the connection member in an oxygen separation membrane module comprising a ceramic connection member joined to the membrane element. This sealing material has the following six constituent elements, the following six mass elements being 100% by mass as a whole in terms of oxides:
SiO ₂ 60 to 78 wt%;
Al ₂ O ₃ 10~22% by weight;
Na ₂ O 3-16% by mass;
K ₂ O 5-16% by mass;
CaO 0 to 4% by mass;
B ₂ O _{30 to} 4% by mass;
The glass mainly comprises glass in which a crystal made of magnesium oxide (MgO) and at least one crystal selected from cristobalite crystal, leucite crystal and forsterite crystal are precipitated in a glass matrix. . Here, the glass further has Mg as a constituent element, and the total composition of the glass is 100% by mass in terms of oxide, and the mass composition of MgO is 13% by mass to 30% by mass. Half of the amount is present as a constituent of the crystals precipitated in the glass matrix.
By using the sealing material which concerns on this aspect, the oxygen separation membrane module in which the sealing part (joining part) excellent in heat resistance and durability as mentioned above was formed can be provided.

In a preferable aspect of the oxygen separation membrane module sealing material disclosed herein, the coefficient of thermal expansion is 10 × 10 ⁻⁶ K ^{−1 to} 14 × 10 ⁻⁶ K ⁻ even after being exposed to a temperature of at least 1200 ° C. ¹ is maintained.
Such a thermal expansion coefficient approximates the thermal expansion coefficient of the constituent members of the oxygen separation membrane module (for example, an oxygen separation membrane or a gas pipe). Thereby, the oxygen separation membrane module provided with the seal part (joint part) which has high heat resistance and durability even if exposed to the above temperature can be provided.

Moreover, this invention provides the manufacturing method of the sealing material for oxygen separation membrane modules as mentioned above. That is, one embodiment of the production method provided by the present invention includes the following steps. That is, the following composition in mass ratio in terms of oxide:
SiO ₂ 60 to 75 wt%;
Al ₂ O ₃ 10-20% by mass;
Na ₂ O 3-15% by mass;
K ₂ O 5-15% by mass;
CaO 0 to 3% by mass;
B ₂ O _{30 to} 3% by mass;
MgO 0 to 3% by mass;
Glass raw material powder prepared so as to be substantially constituted from the above, preparing the glass (glassy intermediate) by melting the raw material powder, and crushing the prepared glass (glassy intermediate) Thereafter, a mixed powder of the glass (glassy intermediate) and the MgO is prepared by adding MgO powder in an amount corresponding to 1% by mass or more and less than 10% by mass of the whole glass raw material powder, and the above The method includes crystallizing the mixed powder to precipitate at least forsterite crystals as crystal components in the glass matrix.

In the manufacturing method of the sealing material having such a configuration, before carrying out the crystallization treatment for precipitating a crystal component in the glass matrix, MgO (mainly as Mg capable of constituting a crystal) separate from MgO that can constitute the glass matrix. By adding the powder to glass (glassy intermediate), at least forsterite crystals can be precipitated from the mixed powder.
Further, the sealing material obtained by such a method has a coefficient of thermal expansion of 10 even in a high temperature region of 1200 ° C. or higher (eg, 1200 ° C.) as compared with the sealing material obtained by adding MgO powder after the crystallization treatment. Since it can be maintained within the range of × 10 ⁻⁶ K ^{−1 to} 14 × 10 ⁻⁶ K ⁻¹ , it can be approximated by the thermal expansion coefficient of each constituent material of the oxygen separation membrane module, and for the oxygen separation membrane module It can be preferably used as a sealing material. Therefore, according to this manufacturing method, there is provided a sealing material suitable for an oxygen separation membrane module, which is a sealing material capable of forming a sealing portion having high airtightness and mechanical strength even under the high temperature range and having an insulating property. be able to.

Moreover, the manufacturing method of the sealing material for oxygen separation membrane modules of another one aspect | mode provided by this invention includes the following processes. That is, the following composition in mass ratio in terms of oxide:
SiO ₂ 60 to 75 wt%;
Al ₂ O ₃ 10-20% by mass;
Na ₂ O 3-15% by mass;
K ₂ O 5-15% by mass;
CaO 0 to 3% by mass;
B ₂ O _{30 to} 3% by mass;
MgO 0 to 3% by mass;
Glass raw material powder prepared so as to be substantially constituted from the above, preparing the glass (glassy intermediate) by melting the raw material powder, and crushing the prepared glass (glassy intermediate) Thereafter, MgO powder is added in an amount corresponding to 10% by mass or more and 30% by mass or less of the entire glass raw material powder to prepare a mixed powder of the glass (glassy intermediate) and MgO, and By crystallizing the mixed powder, a crystal composed of magnesium oxide (MgO) as a crystal component in the glass matrix and at least one crystal selected from cristobalite crystal, leucite crystal and forsterite crystal are obtained. Precipitating.
In the manufacturing method of the sealing material having such a configuration, before carrying out the crystallization treatment for precipitating a crystal component in the glass matrix, MgO (mainly as Mg capable of forming a crystal) separate from MgO capable of forming the glass matrix By adding the powder to the glass (glassy intermediate), a crystal composed of MgO and at least one crystal selected from cristobalite crystal, leucite crystal and forsterite crystal are precipitated from the mixed powder. be able to.
Further, the sealing material obtained by such a method has a coefficient of thermal expansion of 10 even in a high temperature region of 1200 ° C. or higher (eg, 1200 ° C.) as compared with the sealing material obtained by adding MgO powder after the crystallization treatment. Since it can be maintained within the range of × 10 ⁻⁶ K ^{−1 to} 14 × 10 ⁻⁶ K ⁻¹ , it can be approximated by the thermal expansion coefficient of each constituent material of the oxygen separation membrane module, and for the oxygen separation membrane module It can be preferably used as a sealing material. Therefore, according to such a manufacturing method, it is possible to provide a sealing material suitable for an oxygen separation membrane module, which is a sealing material that can form a sealing portion having high hermeticity and mechanical strength even under a high temperature range and having insulating properties. Can do.

In a preferred embodiment of the method for producing a sealing material for an oxygen separation membrane module disclosed herein, as the crystallization treatment, the mixed powder is used in a temperature range (typically 1000 ° C. or lower) at which crystallization can be induced. For example, the process which heats for the appropriate predetermined time (for example, 30 minutes-60 minutes in the temperature range of 800-1000 degreeC) is mentioned at 800-1000 degreeC, for example.
According to the manufacturing method having such a configuration, by performing crystallization treatment under the heating conditions as described above, the sealing material is made of crystal-containing glass in which various crystals are precipitated in a glass matrix, and is used as a sealing material for an oxygen separation membrane module. A suitable sealing material can be provided.

  In another aspect, the present invention provides a method for producing an oxygen separation membrane module by joining (sealing) an oxygen separation membrane element and a connecting member (for example, a gas pipe) using the sealing material as described above. provide. That is, the method for producing an oxygen separation membrane module according to the present invention includes an oxygen separation membrane element including an oxygen separation membrane made of an oxide ceramic having a perovskite structure, which is an oxygen ion conductor, on a porous substrate, and the membrane element. It is a method of manufacturing an oxygen separation membrane module provided with the made ceramic connection member. This method includes the following steps (1) to (4). That is, (1) preparing a membrane element in which a coating film is formed by coating the porous substrate with an oxygen separation membrane material made of oxide ceramics having a perovskite structure; (2) connecting Providing a member; (3) a sealing material comprising any of the sealing materials disclosed herein, wherein the sealing material is made of glass in which a crystal containing at least Mg as a constituent element is precipitated in a glass matrix; A porous base material formed with a connecting member and a connecting member; and (4) the coating element that is provided with the sealing material and connected to each other, and the connecting member. Forming an oxygen separation film formed by baking the coating film on the porous base material by baking in the baking temperature range, and the membrane element and the connection member Encompassing simultaneously be performed, the to be joined together to form a seal that blocks gas flow consisting of the sealing material in the connecting portion.

  In the method for producing an oxygen separation membrane module according to the present invention, the oxygen separation membrane element (for example, the porous substrate and / or oxygen separation membrane in the oxygen separation membrane element) constituting the module is joined to the connection portion of the connection member. Thus, the sealing material disclosed herein is used to form the seal portion. Thus, when forming the oxygen separation film by baking the unfired coating film, the sealing material does not elute even in the baking temperature range of the coating film (for example, 1200 to 1400 ° C.). The part can be preferably formed. Thereby, the formation of the oxygen separation membrane and the formation of the seal portion by the sealing material (joining of the oxygen separation membrane element and the connecting member) can be simultaneously performed by one firing. Therefore, according to this manufacturing method, the formation of an oxygen separation membrane, the efficiency of the manufacturing process and the cost reduction can be realized, and the provision of a high-performance oxygen separation membrane module excellent in heat resistance and durability can be realized.

It is sectional drawing which shows typically one form of an oxygen separation membrane module provided with the oxygen separation membrane element and the gas pipe | tube as a connection member joined to this element.

  Hereinafter, preferred embodiments of the present invention will be described. In addition, matters other than matters specifically mentioned in the present specification (for example, a method for preparing crystal-containing glass constituting the sealing material) and matters necessary for carrying out the present invention (mixing method of raw material powder and oxygen separation) The construction method of the membrane element) can be grasped as a design matter of a person skilled in the art based on the prior art in this field. The present invention can be carried out based on the contents disclosed in this specification and common technical knowledge in the field.

An oxygen separation membrane module according to one aspect disclosed herein (hereinafter sometimes referred to as “first oxygen separation membrane module”) includes an oxygen separation membrane element, a gas pipe, and the like, which are main components (members) thereof. By joining the connecting portion with the connecting member by a glass in which at least forsterite (Mg ₂ SiO ₄ ) crystals are precipitated in the glass matrix (hereinafter sometimes referred to as “crystal-containing glass 1”). It can be characterized. In addition, the crystal-containing glass 1 in such a seal portion has six constituent elements of Si, Al, Na, K, Ca, and B, the total of the six constituent elements being 100% by mass in terms of oxide, and SiO ₂ is 60 to 60%. 78 wt%, _Al 2 _{O 3} is 10 to 22 wt%, Na ₂ O is 3 to 16 wt%, _{K 2} O is 5 to 16 wt%, CaO 0 to 4 _wt%, B 2 _{O 3} is 0 It has a mass composition of 4% by mass, and the glass further has Mg as a constituent element, and the mass composition of MgO in terms of oxide is 1% by mass to 13% by mass with the whole glass being 100% by mass. It is characterized by the fact that half of the amount is present as a constituent of crystals precipitated in the glass matrix.

An oxygen separation membrane module according to another aspect disclosed herein (hereinafter also referred to as “second oxygen separation membrane module”) includes an oxygen separation membrane element and a gas pipe as main components (members). Crystals made of magnesium oxide (MgO) in the glass matrix, cristobalite (SiO ₂ ) crystal, leucite (KAlSi ₂ O ₆ or 4SiO ₂ · Al ₂ O ₃ · K ₂ O) It is characterized by being sealed by a glass in which at least one crystal selected from crystals and forsterite (Mg ₂ SiO ₄ ) crystals is deposited (hereinafter sometimes referred to as “crystal-containing glass 2”). It can be attached. In addition, the crystal-containing glass 2 in such a seal portion has six constituent elements of Si, Al, Na, K, Ca, and B, the total of the six constituent elements being 100% by mass in terms of oxide, and SiO ₂ is 60 to 60%. 78 wt%, _Al 2 _{O 3} is 10 to 22 wt%, Na ₂ O is 3 to 16 wt%, _{K 2} O is 5 to 16 wt%, CaO 0 to 4 _wt%, B 2 _{O 3} is 0 It has a mass composition of 4% by mass, and the glass further has Mg as a constituent element, and the mass composition of MgO in terms of oxide is 13% by mass to 30% by mass with 100% by mass as the whole glass. In addition to the following, at least half of the amount is present as a constituent component of crystals precipitated in the glass matrix.
Therefore, the content and composition of other components can be arbitrarily determined in light of various standards.

The first and second oxygen separation membrane modules disclosed here will be described. In the following description, the description that does not specify the first oxygen separation membrane module or the second oxygen separation membrane module is an explanation common to these oxygen separation membrane modules.
The oxygen separation membrane element constituting the oxygen separation membrane module disclosed herein includes a porous base material and an oxygen separation membrane formed on the base material as main components.
As the porous substrate that functions as a support for the oxygen separation membrane, ceramic porous bodies having various properties that are employed in this type of conventional membrane element (for example, an oxygen separation membrane element) can be used. A material made of a material having stable heat resistance in the use temperature range (for example, 800 ° C. or higher and lower than 1000 ° C.) of the oxygen separation membrane module is preferably used. For example, a ceramic porous body having the same composition as the oxygen separation membrane, or a ceramic porous body mainly composed of magnesia (magnesium oxide), zirconia (zirconium oxide), silicon nitride, silicon carbide, or the like can be used. Alternatively, a metallic porous body mainly composed of a metal material may be used. In this embodiment, MgO, which is inexpensive and easily available, has excellent mechanical strength, and is also included as a constituent of the sealing material disclosed herein, is used.
The shape of such a porous support is not particularly limited. For example, it is a plate shape (including a flat shape, a spherical shape, etc.), a tubular shape (open tube with both ends open, closed with one end opened and the other closed). And the like, and an oxygen separation membrane can be formed on a part or the entire surface of the predetermined portion. Further, the porosity (based on the mercury intrusion method) of the porous substrate is not particularly limited. For example, about 80% by volume or less (typically about 5 to 80% by volume) is appropriate, and preferably 60%. The volume% or less (typically 50-60 volume%). Moreover, as an average pore diameter (based on a mercury intrusion method) of this porous base material, for example, 20 μm or less (typically 0.1 μm to 20 μm) is preferable. The porous substrate having such a porosity and average pore diameter does not hinder the permeation of gas such as oxygen-containing gas, and a thin oxygen separation membrane can be suitably formed on the surface thereof.

  The oxide ceramic constituting the oxygen separation membrane is not limited to a specific constituent element as long as it has a perovskite structure that is an oxygen ion conductor, but has both oxygen ion conductivity and electron conductivity. It is preferably composed of an element that provides an excellent mixed conductor. When the oxygen separation membrane material disclosed herein has mixed conductivity, one side of the oxygen separation membrane (the side to which the oxygen-containing gas is supplied) and the other side (oxygen ions that have permeated the oxygen separation membrane material) Oxygen ions are continuously permeated from one to the other without using an external electrode or an external circuit for short-circuiting the side that is oxidized as oxygen gas or the side that reacts with the supplied hydrocarbon gas) In addition, the oxygen ion permeation rate can be increased.

The oxide ceramics of this type, the general formula _(1): perovskite oxide having a composition represented by _{Ln 1-x A x MO 3} -δ is preferred. Here, Ln in the formula is at least one selected from lanthanoids (typically lanthanum (La)). A is one or more elements of strontium (Sr), barium (Ba), and calcium (Ca), and particularly preferably Sr. M is a metal element that can form a perovskite structure. For example, magnesium (Mg), manganese (Mn), gallium (Ga), titanium (Ti), cobalt (Co), nickel (Ni), aluminum ( Al), iron (Fe, copper (Cu), indium (In), tin (Sn), zirconium (Zr), vanadium (V), chromium (Cr), zinc (Zn), germanium (Ge), scandium (Sc) ) And yttrium (Y).
Further, “x” in the general formula (1) is a value indicating the ratio of Ln (typically La) replaced by A in this perovskite structure. The range that x can take is not particularly limited as long as the structure can be maintained without destroying the perovskite structure, but 0 ≦ x <1 is appropriate, and preferably 0.4 ≦ x ≦ 0.6. is there.
Note that δ is a value determined so as to satisfy the charge neutrality condition. The number of oxygen atoms in the general formula (1) varies depending on the type of atom that substitutes a part of the perovskite structure, the substitution ratio, and other conditions, so that it is difficult to display accurately. Therefore, it is appropriate to adopt a positive number δ (0 <δ <1) that does not exceed 1 as a value that is determined to satisfy the charge neutrality condition, and to display the number of oxygen atoms as 3-δ. Hereinafter, 3 may be displayed for convenience. However, even if the number of oxygen atoms is represented as 3 for convenience, it does not represent a different compound.

In addition, as the perovskite oxide as described above, any one of Co, Ti, Ni, and Fe may be used as M in the general formula (1) (that is, a metal element constituting the B site of the perovskite oxide). What is contained is more preferable. Particularly preferred is a perovskite oxide containing Co that is reactive enough to be used as a catalyst metal. Examples of such perovskite oxides include La _1-x Sr _x Co _1-y Ti _y O ₃ (LSCT oxide), La _1-x Sr _x Co _1-y Ni _y O ₃ (LSCN oxide). ), La _1-x Sr _x Co _1-y Fe _y O ₃ (LSCF oxide). Here, “x” is 0 ≦ x <1 (for example, 0.4 ≦ x ≦ 0.6). In addition, the above “y” is a value indicating the ratio of Co in the perovskite type structure replaced by other metal elements such as Ti and Fe, and the “y” value of the perovskite type cobalt oxide as described above. The range to be obtained is suitably 0 ≦ y <1, and preferably 0.1 ≦ y ≦ 0.5.

  As one preferred example of a ceramic connecting member joined and connected to an oxygen separation membrane element comprising a porous base material made of the material as described above and an oxygen separation membrane, a gas ( For example, a gas pipe for supplying an oxygen-containing gas (typically air) may be mentioned. Such a gas pipe may be the same as a gas pipe generally used for supplying gas to the oxygen separation membrane element, and is not particularly limited. Examples thereof include zirconia-based oxides such as yttria-stabilized zirconia (YSZ), and dense bodies such as cerium oxide, magnesium oxide (magnesia), and mullite. In particular, a gas pipe made of a dense body of YSZ can be approximated to the thermal expansion coefficient of the sealing material and oxygen separation membrane element (for example, the oxygen separation membrane) disclosed herein. It is easy to join to a membrane element and can be used suitably. The shape and size of the gas pipe are appropriately set according to the size of the oxygen separation membrane element to be connected and the size of the joined portion. Hereinafter, the present invention will be described by taking as an example the case where the ceramic connecting member joined to the oxygen separation membrane element is a gas pipe.

  A ceramic porous substrate and a method for producing a connecting member such as a gas pipe are made of ceramic porous bodies having various properties that are employed in conventional membrane elements of this type (for example, oxygen separation membrane elements), or The method may be the same as the method of manufacturing a general gas pipe for supplying gas to the oxygen separation membrane element, and is not particularly limited. For example, conventionally known molding methods such as uniaxial compression molding, isostatic pressing, and extrusion molding can be employed. As a specific example, a slurry-like molding material made of a predetermined material (for example, a powder material such as MgO powder or YSZ powder having an average particle diameter of about 0.1 μm to 10 μm, a binder, a dispersant, and a solvent) is prepared. Subsequently, the molding material is used to extrude into a predetermined shape (typically both a porous base material and a gas pipe are tubular or cylindrical) and a size. A porous substrate and a gas pipe can be produced by firing the obtained molded body in an oxidizing atmosphere (for example, in the air) or an inert gas atmosphere at an appropriate temperature range (for example, 1300 to 1600 ° C.). . In addition, about a porous base material and a connection member, you may use a commercial item (off-the-shelf product).

In addition, a method for forming an oxygen separation membrane made of oxide ceramics having a perovskite structure on a porous substrate is not particularly limited, and various conventionally known methods can be employed. As a preferred example, first, an oxygen separation membrane material powder made of a perovskite oxide (for example, LSCN oxide) to be manufactured is prepared. Next, a slurry is prepared by mixing with an appropriate binder, dispersant, plasticizer, solvent, etc., and the slurry is coated on the surface of the porous substrate (for example, a tubular porous substrate) by a general method such as dip coating. (Outer peripheral surface) can be applied (applied). About the thickness dimension of the coating material (coating film | membrane) provided to the porous base material surface, it sets suitably according to the film thickness which the oxygen separation film obtained by baking this coating film | membrane obtains. The thickness of the oxygen separation membrane is suitably in the range of 1000 μm or less, preferably 200 μm or less (typically about 5 μm to 200 μm), and more preferably about 100 μm or less (typical). Is in the range of about 5 μm to 100 μm), and the thinner is preferable. For this reason, the film thickness of the coating film is set so that the thickness dimension is in the above range after the coating film is baked. In this embodiment, since the oxygen separation membrane is supported by the porous substrate, the oxygen separation membrane itself is not required to have mechanical strength, and the above-described application is performed as long as the denseness of the oxygen separation membrane is maintained. The lower limit of the thickness dimension of the film is not particularly limited.
Thus, a coating film (non-fired oxygen separation film) made of oxide ceramics (for example, LSCN oxide or LSCT oxide) having a perovskite structure can be formed on the surface of the porous substrate (support). In addition, you may dry the coating material (coating film) formed on the porous base material at suitable temperature (typically 60-100 degreeC). Or after giving a sealing material to the joined part with a gas pipe like the after-mentioned, you may dry both the said coating film and a sealing material collectively.

As the oxygen separation membrane material powder, a commercially available perovskite oxide powder (for example, LSCN oxide) prepared in advance to a predetermined composition may be used. Alternatively, an oxide containing a metal element (for example, La, Sr, Co, Ni) constituting the perovskite oxide to be produced, or a compound that can be converted into an oxide by heating (a carbonate, nitrate, sulfate of the metal atom) , Phosphates, acetates, oxalates, halides, hydroxides, oxyhalides, etc.), each of which is blended at a blending ratio corresponding to the composition ratio of the perovskite oxide. A powder obtained by firing (calcining) the powder can also be used as the material powder for the oxygen separation membrane. Such a starting material may contain a compound (a composite metal oxide, a composite metal carbonate, or the like) containing two or more metal elements among the metal elements constituting the perovskite oxide. In addition, a slurry is prepared by adding and mixing a molding aid such as water and an organic binder, and a dispersant to the oxygen separation membrane material powder, and using a granulator such as a spray dryer, the desired particles are obtained. You may granulate to a diameter (for example, an average particle diameter of 10 micrometers-100 micrometers).
As described above, it is possible to obtain a membrane element in which a coating film (non-fired oxygen separation membrane) made of oxide ceramics having a perovskite structure is formed on a porous substrate, and bonded to the membrane element. Gas pipes can be obtained.

Next, the sealing material for an oxygen separation membrane module will be described.
The sealing material of one aspect disclosed herein (hereinafter sometimes referred to as “sealing material 1”) is such that the glass constituting the sealing material contains at least forsterite in the crystal-containing glass 1, that is, the glass matrix. It is characterized by being a glass on which Mg ₂ SiO ₄ ) crystals are precipitated. Further, the sealing material according to another embodiment disclosed herein (hereinafter sometimes referred to as “sealing material 2”) is such that the glass constituting the sealing material is the above-described crystal-containing glass 2, that is, in the glass matrix. Further, it is characterized by being a glass in which crystals composed of magnesium oxide (MgO) crystals, cristobalite crystals and / or leucite crystals are precipitated.
The sealing materials 1 and 2 disclosed herein are sealing materials (joining materials) for sealing and joining the oxygen separation membrane element and the connecting member (in this embodiment, gas pipes) configured as described above. It is.

The crystal-containing glasses 1 and 2 constituting the sealing materials 1 and 2 will be described. In the following description, the description that does not specify the crystal-containing glass 1 or the crystal-containing glass 2 is an explanation common to these crystal-containing glasses. The same applies to the case where the first or second sealing material is not specified.
The crystal-containing glass disclosed here is used in an oxygen separation membrane module operating temperature range (typically 800 ° C. or higher and lower than 1000 ° C., for example, 900 ° C. or higher and lower than 1000 ° C.) and higher (typically 1000 ° C. or higher, In particular, a glass having a composition that hardly melts in a high temperature range of 1200 ° C. or higher, for example, 1200 to 1300 ° C., more preferably 1200 to 1400 ° C. or higher) is preferable. In this case, a desired high melting point (high softening point) can be realized by adding or increasing a component that increases the melting point (softening point) of the glass.
Such crystal-containing glass contains Si, Al, Na, and K as its essential constituent elements, and may contain Ca and B as optional (additional) constituent elements. These six constituent elements are converted into their oxide state (ie, silicon oxide (SiO ₂ ), aluminum oxide (Al ₂ O ₃ ), sodium oxide (Na ₂ O), potassium oxide (K ₂ O) and optionally oxidized. Oxide glass contained as calcium (CaO) or boron oxide (B ₂ O ₃ )) is preferable. In addition to these components, various components (typically, various oxide components) can be further included in addition to these components as long as they do not prevent the precipitation of crystals suitable for the practice of the present invention.
In addition, for cristobalite crystals and / or leucite crystals among the crystal components of the crystal-containing glass, the amount of such crystals precipitated is the content of the above constituent elements (essential constituent elements) in the crystal-containing glass in terms of oxide (mixing ratio) ) Can be adjusted as appropriate.
The mass composition of the crystal-containing glass on which such crystals can be precipitated is the total of the above six constituent elements (that is, SiO ₂ , Al ₂ O ₃ , Na ₂ O, K ₂ O, CaO and B _{2 in} terms of oxide). O ₃₎ as 100 mass%, SiO ₂ is 60 to 78 wt%, _Al 2 _{O 3} is 10 to 22 wt%, Na ₂ O is 3 to 16 wt%, _{K 2} O is 5 to 16 wt%, CaO Is preferably 0 to 4% by mass, and B ₂ O ₃ is preferably 0 to 4% by mass.

SiO ₂ is a component constituting a cristobalite crystal, a leucite crystal, and a forsterite crystal, and is a main component constituting a skeleton of a glass layer (glass matrix) at a joint portion. If the SiO ₂ content is too high, the melting point (softening point) becomes too high, which is not preferable. On the other hand, if the SiO ₂ content is too low, the amount of cristobalite crystals and / or leucite crystals deposited can be reduced. In addition, water resistance and chemical resistance are reduced. It is preferred SiO ₂ content of from 60 to 75 wt% of the total crystal-containing glass.

Al ₂ O ₃ is a component constituting a leucite crystal, and is a component involved in adhesion stability by controlling the fluidity of glass. If the Al ₂ O ₃ content is too low, the adhesion stability may be reduced, and the formation of a glass layer (glass matrix) having a uniform thickness may be impaired, and the amount of leucite crystal precipitation may be reduced. On the other hand, if the Al ₂ O ₃ content is too high, the chemical resistance of the joint may be lowered. It is preferable al ₂ O ₃ content is 10 to 20 wt% of the total crystal-containing glass.

K ₂ O is a component constituting the leucite crystal, and is a component that increases the thermal expansion coefficient (thermal expansion coefficient) together with Na ₂ O. If the K ₂ O content is too low, the amount of leucite crystal precipitation can be reduced. Further, if the K ₂ O content and the Na ₂ O content are too low, the thermal expansion coefficient may be too low. On the other hand, if the K ₂ O content and the Na ₂ O content are too high, the thermal expansion coefficient becomes excessively high, which is not preferable. It is preferred K ₂ O content is 5 to 15 wt% of the total crystal-containing glass. Further, it is preferable that Na ₂ O content is 3 to 15 wt% of the total crystal-containing glass. It is particularly preferable that the total of K ₂ O and Na ₂ O is 10 to 20% by mass of the entire crystal-containing glass.

  CaO, which is an alkaline earth metal oxide, is an optional additive component that can adjust the thermal expansion coefficient. CaO is a component that can increase the hardness of the glass matrix and improve the wear resistance. The content of CaO in the entire crystal-containing glass is preferably zero (no addition) or 3% by mass or less.

B ₂ O ₃ is also an optional additive component. B ₂ O ₃ is considered to exhibit the same action as Al ₂ O ₃ in glass, and can contribute to the multi-componentization of the glass matrix. Moreover, it is a component which contributes to the improvement of the meltability at the time of sealing material preparation. On the other hand, too much of this component is not preferable because it causes a decrease in acid resistance. The content of B ₂ O _{3 in} the entire crystal-containing glass is preferably zero (no addition) or about 3% by mass or less.
In addition to the oxide components described above, components that are not essential in the practice of the present invention (for example, ZnO, Li ₂ O, Bi ₂ O ₃ , SrO, SnO, SnO ₂ , CuO, Cu ₂ O, TiO ₂ , ZrO) ₂ , La ₂ O ₃ ) can be added according to various purposes.

  Moreover, the crystal-containing glass disclosed here includes Mg as an essential constituent element in addition to the constituent elements in both the crystal-containing glass 1 and the crystal-containing glass 2. In addition, such crystal-containing glass may contain at least half (half amount) of Mg as a constituent component of the crystal component, and it is arbitrary whether Mg is included or not included as a constituent component of the glass matrix. For example, when Mg (typically MgO) is contained as a constituent component of the glass matrix, it becomes a component capable of adjusting the coefficient of thermal expansion together with CaO of the alkaline earth metal oxide. In this case, the coefficient of thermal expansion can be adjusted by adjusting the viscosity at the time of melting the glass.

  Moreover, in the crystal-containing glass disclosed here, the types of crystal components that can be precipitated in the glass matrix may differ depending on the content (mass composition) of Mg contained in the glass. That is, in the crystal-containing glass, the mass composition of Mg is the oxide-based (MgO-converted) whole crystal-containing glass (all the above-described constituent elements including Mg, for example, Si, Al, Na, K, and Ca described above). When B, Mg are constituent elements, the total amount of these elements in terms of oxide) is 100% by mass or more and less than 13% by mass, and at least forsterite in the glass matrix. The crystal-containing glass 1 has a composition in which crystals are precipitated. In addition, at least half of the MgO contained in the crystal-containing glass 1 with the mass composition (content) as described above is a constituent component of crystals (mainly forsterite crystals) that can be precipitated in the crystal-containing glass 1. It is preferable that the remaining Mg can be included as a glass component of the crystal-containing glass 1 (a constituent component of the glass matrix). More preferably, about 50 to 75% by mass of Mg contained in the crystal-containing glass 1 can contribute as a constituent element (component) of the precipitated crystal. The crystal-containing glass 1 may include, for example, a cristobalite crystal, a leucite crystal, etc. as a crystal other than the forsterite crystal.

  On the other hand, when the mass composition of Mg is 13% by mass or more and 30% by mass or less when the total crystal-containing glass is 100% by mass in terms of oxide, the crystal-containing glass is contained in the glass matrix. The crystal-containing glass 2 has a composition in which a crystal made of MgO and at least one of a cristobalite crystal, a leucite crystal, and a forsterite crystal can be precipitated. In addition, at least half of the MgO contained in the crystal-containing glass 2 with the mass composition (content) as described above is included as a constituent component of crystals (mainly MgO crystals) that can be precipitated in the crystal-containing glass 2. It is preferable that More preferably, about 75 to 90% by mass of Mg in the crystal-containing glass 2 can contribute as a constituent element (component) of the crystal. Furthermore, within the range of the mass composition (content rate) of Mg, as the content rate increases, the proportion of the MgO crystals in the precipitated crystals can be increased.

As described above, among the plurality of crystals that can be precipitated in the glass matrix of the crystal-containing glass, a forsterite crystal or an MgO crystal can be present together with other crystals, whereby the seal made of such a crystal-containing glass. Even if the seal portion formed using the material is exposed to a high temperature of, for example, 1200 ° C. or higher, re-dissolution of each crystal (for example, cristobalite crystal or leucite crystal) precipitated in the glass matrix is prevented. A decrease in the thermal expansion coefficient of the seal portion can be suppressed. Therefore, a crystal-containing glass suitable as a sealing material for an oxygen separation membrane module that achieves both heat resistance and airtightness at a high level can be obtained. Here, as described above, the mass composition of Mg in the crystal-containing glass is 1% by mass or more and less than 13% by mass or 13% by mass or more and 30% by mass in terms of oxide (MgO conversion). It is preferable that it is below mass%. When the mass composition is less than 1% by mass, there is a possibility that various crystals in the crystal-containing glass may be redissolved in the sealing material made of the crystal-containing glass. From this viewpoint, the mass composition of Mg is more preferably 3% by mass or more of the entire crystal-containing glass in terms of oxide.
In addition, the thermal expansion coefficient of the sealing material after being exposed to a temperature of at least 1200 ° C. (average value between room temperature (25 ° C.) and 500 ° C. based on a general differential expansion method (TMA)) is greatly increased. There is a risk that the difference between the thermal expansion coefficient of the parts to be joined widens and the seal part peels off, cracks, etc., and the mechanical strength of the seal part decreases. On the other hand, if the mass composition is more than 30% by mass, the content of the crystal component (mainly MgO crystal) in the crystal-containing glass is too large, and the glass component is reduced, and MgO cannot be completely sintered. For this reason, the denseness of the seal portion cannot be ensured, and there is a possibility that a seal portion having high airtightness cannot be formed. From this viewpoint, the mass composition of Mg is more preferably 20% by mass or less of the entire crystal-containing glass in terms of oxide. For example, the mass composition of Mg is more preferably 3% by mass or more and 20% by mass or less of the entire crystal-containing glass in terms of oxide.

In the preparation of the sealing material comprising the crystal-containing glass having the above composition, preferably, the thermal expansion coefficient of the sealing material approximates the thermal expansion coefficient of the object to be joined (a connecting member such as an oxygen separation membrane element and a gas pipe). Thus, it carries out by preparing each component (composition) component of this crystal-containing glass. As an example, oxygen gas is sealed (sealed) between a gas tube formed of a dense body of zirconia-based oxide such as YSZ and a dense oxygen separation membrane made of LSCT oxide of a perovskite oxide. When joining a separation membrane element (a porous substrate made of MgO in the above) and a gas pipe, the thermal expansion coefficient of the zirconia-based oxide, perovskite oxide, or MgO (or the entire joined portion, or the above) The composition is adjusted so that the thermal expansion coefficient is 10 × 10 ⁻⁶ K ^{−1 to} 14 × 10 ⁻⁶ K ⁻¹ by approximating the thermal expansion coefficient of the entire assembly of the oxygen separation membrane element and the gas pipe). What is necessary is just to prepare and to prepare the said crystal | crystallization containing glass (seal material which consists of).

Here, in a sealing material comprising a glass composition containing the glass component having the above composition and the cristobalite crystal and / or the leucite crystal (that is, a glass composition not containing forsterite crystal or MgO crystal), oxygen separation is performed. When exposed to a typical use temperature range of the membrane module (for example, 800 ° C. or more and less than 1000 ° C.), the above-mentioned crystal component does not re-dissolve, and the thermal expansion coefficient is not limited to each component of the oxygen separation membrane module. The thermal expansion coefficient (for example, 10 × 10 ⁻⁶ K ^{−1 to} 14 × 10 ⁻⁶ K ⁻¹ ) as the entire member or module (the entire assembly of the oxygen separation membrane element and the connection member) can be approximately the same. However, when exposed to a high temperature range above the use temperature range, for example, 1000 ° C. or more, particularly 1200 ° C. or more (for example, 1200 to 1300 ° C., more preferably 1200 to 1400 ° C.), the crystal component is dissolved again. And the thermal expansion coefficient can be significantly reduced (for example, 6 × 10 ⁻⁶ K ^{−1 to} 9 × 10 ⁻⁶ K ⁻¹ ). Therefore, a seal portion (joint portion) formed using such a sealing material is It was difficult to realize excellent heat resistance in a high temperature range such as 1200 ° C. or higher.

In contrast to such a forsterite crystal or MgO crystal-free sealing material, a sealing material composed of the crystal-containing glass disclosed herein (that is, a crystal-containing glass containing forsterite crystal or MgO crystal) is, for example, oxygen Even when exposed to a high temperature range of 1200 ° C. or higher (for example, 1200 to 1300 ° C., preferably 1200 to 1400 ° C. or higher) during firing of the separation membrane, the crystalline component does not re-dissolve and does not elute from the bonded portion. Moreover, since the thermal expansion coefficient can be maintained at 10 × 10 ⁻⁶ K ^{−1 to} 14 × 10 ⁻⁶ K ⁻¹ , formation of a seal portion having excellent heat resistance is realized. Therefore, by using the sealing material made of the crystal-containing glass disclosed here, a seal portion having high hermeticity and mechanical strength is formed even when exposed to a high temperature range of 1200 ° C. or higher, and gas leakage is caused over a long period of time. Production of a high-performance oxygen separation membrane module that can be prevented at a high level can be realized.

Next, a method for manufacturing such a sealing material will be described.
The manufacturing method of the sealing material of 1 aspect disclosed here is a method of manufacturing the sealing material 1 comprised from the crystal-containing glass 1, Comprising: It is preferable that the following processes are included. That is, the manufacturing method first comprises (1) the following composition in terms of mass ratio in terms of oxide:
SiO ₂ 60 to 75 wt%;
Al ₂ O ₃ 10-20% by mass;
Na ₂ O 3-15% by mass;
K ₂ O 5-15% by mass;
CaO 0 to 3% by mass;
B ₂ O _{30 to} 3% by mass;
MgO 0 to 3% by mass;
A glass raw material powder prepared so as to be substantially constituted from the above, and melting the raw material powder to prepare glass (glassy intermediate); (2) the glass prepared above (glassy intermediate) ), The MgO powder is added in an amount corresponding to 1% by mass or more and less than 10% by mass (preferably 3% by mass or more and less than 10% by mass) of the entire glass raw material powder, and the glass (glassy intermediate) And (3) precipitating at least forsterite crystals as crystal components in the glass matrix by crystallizing the mixed powder.

Moreover, the manufacturing method of the sealing material of the other aspect disclosed here is a method of manufacturing the sealing material 2 comprised from the crystal containing glass 2, Comprising: It is preferable that the following processes are included. That is, the manufacturing method first comprises (1) the following composition in terms of mass ratio in terms of oxide:
SiO ₂ 60 to 75 wt%;
Al ₂ O ₃ 10-20% by mass;
Na ₂ O 3-15% by mass;
K ₂ O 5-15% by mass;
CaO 0 to 3% by mass;
B ₂ O _{30 to} 3% by mass;
MgO 0 to 3% by mass;
A glass raw material powder prepared so as to be substantially constituted from the above, and melting the raw material powder to prepare glass (glassy intermediate); (2) the glass prepared above (glassy intermediate) ) Is added, and MgO powder is added in an amount corresponding to 10% by mass or more and 30% by mass or less (preferably 10% by mass or more and 20% by mass or less) of the entire glass raw material powder, and the glass (glassy intermediate) is added. And (3) by crystallizing the mixed powder, a crystal composed of MgO as a crystal component in the glass matrix, cristobalite crystal, leucite crystal and Depositing at least one crystal selected from stellite crystals.

  Further, in the manufacturing method, in the step of adding the MgO powder, the MgO powder is added to the glass (glassy intermediate) powder before the crystallization treatment, and the mixed powder after the addition of the MgO powder is added. It is preferable to perform a crystallization treatment. In a sealing material in which the mixed powder after the addition of MgO is crystallized to precipitate crystal components (typically, a plurality of crystal components are simultaneously precipitated), the glass (glassy intermediate) is previously crystallized by crystallization treatment. Compared to sealing materials obtained by adding MgO to glass on which crystal components have been deposited (typically heat treatment after the addition), it suppresses a decrease in thermal expansion coefficient at high temperatures such as 1200 ° C or higher. Effect can be improved.

Hereinafter, a preferable example of the manufacturing method of the sealing material disclosed herein will be described.
First, a compound for obtaining an oxide component of each constituent element of such a sealing material (crystal-containing glass) (for example, an industrial product, a reagent containing each component, an oxide, a carbonate, a nitrate, a composite oxide, or the like, or Various mineral raw materials) and other additives as necessary (typically, an admixture obtained by mixing them) are prepared as glass raw material powders. Such glass material powder, SiO ₂ is 60 to 75 wt% in mass ratio of oxide equivalent, _Al 2 _{O 3} is 10 to 20 wt%, Na ₂ O 3 to 15 wt%, _{K 2} O 5-15 It is preferably prepared so as to be substantially composed of such a composition that the mass%, CaO is 0 to 3 mass%, B ₂ O ₃ is 0 to 3 mass%, and MgO is 0 to 3 mass%. . The average particle size of the compound (typically powder) for obtaining each of the oxide components is preferably about 1 μm to 10 μm. Each of these compounds and additives are put into a mixer such as a dry or wet ball mill so as to have the above composition ratio, and mixed for several hours to several tens of hours. The admixture (glass raw material powder) thus obtained is dried, placed in a refractory crucible, and heated and melted under suitable high temperature (typically 1000 to 1500 ° C.) conditions. In this way, glass (glassy intermediate) having the above composition is prepared.

Next, the obtained glass (glassy intermediate) is pulverized to an appropriate size (particle size) to produce glass (glassy intermediate) powder. It is preferable to carry out a classification treatment after the glass pulverization treatment. The particle size (average particle size) of the glass powder is not particularly limited as long as it is easy to uniformly mix with MgO powder added later and is easy to handle. For example, a range of 0.5 μm to 50 μm is appropriate. And preferably 1 μm to 10 μm.
The MgO powder is added to the glass (glassy intermediate) powder obtained by this pulverization at the above blending ratio. The MgO powder added here can also contribute as a constituent component of the glass matrix in the crystal-containing glass 1 or the crystal-containing glass 2 finally obtained, but is a crystal mainly containing Mg that can be precipitated in the glass matrix as a constituent element. It can contribute to the formation of at least forsterite crystals in the case of the crystal-containing glass 1 and MgO crystals and / or forsterite crystals in the case of the crystal-containing glass 2. As the average particle diameter of the MgO powder, it is easy to form a mixed powder uniformly mixed with the glassy intermediate powder, and in the subsequent crystallization treatment, the crystal containing Mg as a constituent element together with other crystals A size capable of being preferably deposited is preferred. Such an average particle size is preferably 0.1 μm to 10 μm, more preferably 0.5 μm to 5 μm.
The addition amount of the MgO powder is suitably 1 to 30% by mass (preferably 3 to 20% by mass) with respect to the total mass of the glass raw material powder in terms of oxide. It is. Here, when the added amount is 1% by mass or more and less than 10% by mass, at least forsterite crystals can be precipitated as a crystal component in the finally obtained crystal-containing glass (crystal-containing glass 1) (others) Crystal such as cristobalite crystal or leucite crystal may also be precipitated). Moreover, when the addition amount of the MgO powder is 10% by mass to 30% by mass of the whole glass raw material powder, the crystal-containing glass (crystal-containing glass 2) to be obtained contains MgO crystals as crystal components and the crystals. In addition, at least one of a cristobalite crystal, a leucite crystal, and a forsterite crystal may be precipitated.

Next, the added MgO powder and the glass (glassy intermediate) powder are mixed for several hours to several tens of hours using a mixer such as a dry or wet ball mill in the same manner as described above. In this way, a mixed powder in which MgO and glass are uniformly mixed is obtained. The average particle size of the mixed powder is preferably 0.5 μm to 10 μm, more preferably 1 μm to 5 μm.
Next, a crystallization process is performed on the mixed powder obtained as described above. In this crystallization treatment, the mixed powder is subjected to a temperature range in which crystallization can be induced, for example, a temperature range of 1000 ° C. or less and a relatively high temperature range (eg, 600 to 1000 ° C., more preferably 800 to 1000 ° C.). And it is good to heat for predetermined time (Typically 30 minutes or more, for example, 30 minutes-60 minutes). As a preferred example, the mixed powder is heated from room temperature to about 100 ° C. at a temperature rising rate of about 1 to 5 ° C./min, from about 100 ° C. at a temperature rising rate of 1 to 10 ° C./min, After maintaining at a temperature range of 800 ° C. or higher and 1000 ° C. or lower for about 30 minutes to 60 minutes, it is cooled to room temperature at a temperature drop rate of about 1 to 5 ° C./min. Thus, the various crystals can be simultaneously precipitated in the glass matrix. In this way, the crystal-containing glass 1 or 2 can be produced.
The crystal-containing glass 1 or 2 thus obtained can be formed into a desired form by various methods. For example, the powder-containing crystal-containing glass 1 or 2 having a desired average particle diameter (for example, 0.1 μm to 10 μm) can be obtained by pulverizing with a ball mill or appropriately sieving (classifying).
Further, an appropriate amount of water is added to the obtained powdery crystal-containing glass 1 or 2 and mixed using a ball mill similar to the above. Then, the powder-form sealing material (sealing material 1 or 2) of the aspect disclosed here can be obtained by implementing the drying process for predetermined time.

The powdery sealing material thus obtained is typically prepared in the form of a paste (slurry) in the same manner as a conventional sealing material (joining material), and a connection portion (joined portion) to be joined. ) Can be applied. For example, a paste can be prepared by mixing an appropriate binder or solvent with the obtained sealing material. In addition, the binder, solvent, and other components (for example, dispersant) used in the paste are not particularly limited, and can be appropriately selected from conventionally known ones in paste production.
For example, a suitable example of the binder includes cellulose or a derivative thereof. Specific examples include hydroxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropyl methyl cellulose, carboxymethyl cellulose, carboxyethyl cellulose, carboxyethyl methyl cellulose, cellulose, ethyl cellulose, methyl cellulose, ethyl hydroxyethyl cellulose, and salts thereof. It is preferable that a binder is contained in 5-20 mass% of the whole paste.

  Examples of the solvent that can be contained in the paste include ether solvents, ester solvents, ketone solvents, and other organic solvents. Preferable examples include ethylene glycol and diethylene glycol derivatives, high-boiling organic solvents such as toluene, xylene and terpineol, or combinations of two or more thereof. Although the content rate of the solvent in a paste is not specifically limited, About 1-40 mass% of the whole paste is preferable.

The sealing material prepared in a paste form as described above can be used in the same manner as this type of pasty sealing material. That is, in this embodiment, the coating film and / or the porous substrate and the connecting member (gas pipe) in the membrane element to be bonded (the film element in which the unfired coating film is formed on the porous substrate) The parts to be joined are contacted and connected to each other, and a paste prepared in the form of a paste is applied (applied) to the connected parts. Then, the coated material is dried at an appropriate temperature (typically 60 to 100 ° C., for example, 80 ° C. ± 10 ° C.) for about 1 to 12 hours, for example.
Next, a module in which a sealing material is provided between the membrane element in which the coating film is formed on the porous substrate and the gas pipe is fired at a predetermined firing temperature. The firing temperature is a temperature suitable for firing the coating film (unfired oxygen separation film) made of oxide ceramics having the perovskite structure to form an oxygen separation film, and a temperature at which the sealing material does not elute. It is preferable that As such temperature, 1200 degreeC or more is suitable, Preferably it is 1200-1300 degreeC, More preferably, it is 1200-1400 degreeC. Moreover, it is preferable to calcinate in such temperature range for about 3 hours to 10 hours (preferably 4 hours to 8 hours, more preferably 5 hours to 7 hours) in an oxidizing atmosphere or an inert gas atmosphere. As a result, a joint portion (seal portion) that shuts off gas flow (that is, has no gas leak) is formed at the connection (connection) portion between the oxygen separation membrane element and the gas pipe. And the said coating film is baked and an oxygen separation film is formed on a porous base material.
From the above, a joined body in which the joint between the oxygen separation membrane element and the connecting member (gas pipe) is sealed by the sealing material (sealing material 1 or sealing material 2), and the joined body is a basic (main) structure. An oxygen separation membrane module (first or second oxygen separation membrane module) provided as an element is manufactured.

  The method for producing the oxygen separation membrane module as described above is characterized by the characteristics of the sealing material used for joining (sealing) between the oxygen separation membrane element and the connecting member (gas pipe), that is, 1200 ° C. or higher (eg, 1200 to 1300 ° C., preferably Is used at a temperature of 1200 to 1400 ° C. or higher), and by using a sealing material having such characteristics, the formation of the seal portion and the formation of the oxygen separation membrane by the above-mentioned bonding are performed. It is possible to carry out simultaneously in the baking process of the film. Thereby, the efficiency of the manufacturing process of an oxygen separation membrane module and the cost reduction accompanying this can be realized. In addition, due to another characteristic of the sealing material, that is, a characteristic that can have a thermal expansion coefficient that approximates the thermal expansion coefficient of the joint portion between the oxygen separation membrane element and the connection member even at a high temperature as described above, the oxygen separation membrane Even when exposed to the operating temperature range of the module, the sealing portion formed using the sealing material maintains high airtightness and durability, and gas (for example, oxygen-containing gas, typically air) flowing through the gas pipe Is supplied to the oxygen separation membrane element without leaking at the seal portion. Therefore, according to the manufacturing method according to the present invention, a high-performance oxygen separation membrane module having excellent heat resistance and durability is provided.

Here, as a suitable joining portion between the oxygen separation membrane element and the connecting member (gas pipe) and the sealing material preferably used, an oxygen separation membrane which is a dense membrane and a dense gas pipe are used. As long as the gas (for example, oxygen-containing gas) flowing through the gas pipe is supplied to the oxygen separation membrane element without leaking, there is no particular limitation.
As a preferred example of the configuration of the oxygen separation membrane module that realizes the gas supply to the oxygen separation membrane element without causing gas leakage, there is an oxygen separation membrane module 100 having a configuration as shown in FIG. The oxygen separation membrane module 100 includes axially opposite ends 15a and 15b of an oxygen separation membrane element 10 in which an oxygen separation membrane 14 is formed on the outer peripheral surface 13 of a tubular (cylindrical) porous substrate 12, respectively. It has the structure connected with the gas pipes 20 and 30 of the tubular shape (for example, the same diameter as this element). Further, the end surfaces in the axial direction of the gas pipes 20 and 30 and the end surfaces in the axial direction of the porous substrate 12 in the oxygen separation membrane element 10 are in contact with each other to form connection surfaces 25 and 35. Further, the sealing material 40 is applied so that the two are joined via the connecting surfaces 25 and 35 to form a seal portion 40, and the sealing material 40 extends beyond the connecting surfaces 25 and 35. The seal is provided so as to cover a part of the oxygen separation membrane 14, and the sealing material 40 seals the gap between the dense gas pipes 20, 30 and the dense oxygen separation membrane 14. A part (40) is formed.
Here, the oxygen separation membrane element 10 (both end portions 15a and 15b, strictly speaking, the end surface in the axial direction of the porous substrate 12) and the connecting portions (coupling surfaces 25 and 35) of the gas pipes 20 and 30 are joined ( When sealing, the oxygen separation membrane element 10 and the gas pipes 20 and 30 are not directly connected to each other, and a connecting member (for example, the same quality as the gas pipes 20 and 30) made of a connecting member different from the gas pipe (not shown) is provided therebetween. It is also possible to seal the oxygen separation membrane element 10, the connecting member and the gas pipe with each other by using the sealing material. Alternatively, as another example of using another connecting member, the gas supplied from one gas pipe (for example, the gas pipe 20) is formed in the oxygen separation membrane element 10 (that is, from the inner diameter of the tubular porous substrate). Rather than a configuration in which the gas is discharged from the other gas pipe (for example, the gas pipe 30) through the hollow portion 17), one of the gas pipes 20 and 30 (for example, the gas pipe 30) is not shown in the figure. The oxygen separation membrane element 10 is replaced with a cap member, and one end of the oxygen separation membrane element 10 is sealed, and the flow of the gas supplied by the lid-like member (cap member) is stopped and is not discharged from the oxygen separation membrane element 10. Examples include an oxygen separation membrane module.
As described above, in the oxygen separation membrane module having various connection members other than the gas pipe, the connection member and the oxygen separation membrane element 10 are joined (sealed) by using the sealing material. Can do.
In addition to the oxygen separation membrane element 10 and the gas pipes 20 and 30 as main components, the oxygen separation membrane module 100 includes a chamber 50 for accommodating the oxygen separation membrane element 10 as shown in FIG. It is preferable to provide as a component. By providing the chamber 50, other gas (for example, hydrocarbon gas) can be supplied into the chamber 50, and separated from the air supplied from the other gas and the gas pipe 20 by the oxygen separation membrane 14. Oxygen can be reacted in the chamber 50 (for example, partial oxidation reaction).

  In the above manufacturing method, the formation of the oxygen separation membrane and the formation of the seal portion were performed at the same time. However, the sealing material disclosed here forms the oxygen separation membrane by baking the coating film on the porous substrate. After the oxygen separation membrane element has been manufactured, the oxygen separation membrane element and the connecting member (gas pipe) can be preferably used. That is, after applying the sealing material to the connecting portion of the oxygen separation membrane element having the oxygen separation membrane that has already been formed and the gas pipe and drying it under the same conditions as described above, a predetermined firing temperature is obtained. The oxygen separation membrane module in which the oxygen separation membrane element and the gas pipe are joined can be manufactured by firing the material to form a seal portion. In such a case, the firing temperature when forming the oxygen separation membrane by firing the coating film is not particularly limited to a temperature range in which the seal material can be used, and a typical oxide ceramic having a perovskite structure can be fired. The temperature may be 1000 to 1800 ° C. (preferably 1200 to 1600 ° C.). In the firing performed after the formation of the oxygen separation membrane and the firing for forming the seal portion, the operating temperature range of the oxygen separation membrane module (for example, a temperature range of 800 ° C. or more and less than 1000 ° C. or higher, For example, when the operating temperature range is 800 ° C. or higher and lower than 1000 ° C., it is typically 1000 to 1200 ° C. In the case where the temperature range exceeds 1000 ° C. and is generally up to 1200 ° C., it is typically fired at 1200 to 1300 ° C. or 1400 ° C. or less.

  Hereinafter, examples related to the present invention will be described with reference to FIG. 1, but the present invention is not intended to be limited to those shown in the following examples.

<Preparation of porous substrate made of MgO>
A molding aid such as a binder was mixed with commercially available magnesia (MgO) powder and kneaded with a ball mill or the like. Thereafter, it was press-molded under a pressure of 100 MPa to obtain a cylindrical molded body having an outer diameter of 20 mm and a thickness (wall thickness) of about 3 mm. Next, the molded body was pre-baked at 350 ° C. for about 2 hours in the air to remove the binder, and further subjected to main baking at 1400 ° C. for about 6 hours in the air to obtain a sintered body (porous Quality substrate).

<Preparation of oxygen separation membrane made of oxide ceramics with perovskite structure>
As an oxygen separation membrane material powder, La _0.5 Sr _0.5 Co _0.9 Ni _0.1 O ₃ (LSCN oxide) powder having an average particle diameter of about 1 μm was prepared. An appropriate amount of a general binder and a solvent (water) were added to the powder and mixed to prepare a slurry-like oxygen separation membrane material.
Next, the slurry-like oxygen separation membrane material was applied to the outer peripheral surface of the obtained MgO porous substrate by dip coating. And this was dried at 80 degreeC. In this way, a membrane element having a coating film made of LSCN oxide was obtained.
Next, as the oxygen separation membrane material powder, La _0.6 Sr _0.4 Co _0.6 Ti _0.4 O ₃ (LSCT oxide) powder having an average particle size of about 1 μm was prepared. Using this powder, a membrane element having a coating film made of LSCT oxide was produced in the same manner as described above.

<Production of gas pipe>
A gas pipe as a connecting member joined to the membrane element was produced as follows. That is, the same binder, dispersant and solvent as described above were added to an MgO powder (average particle size: about 1 μm) and kneaded to prepare a slurry or paste-like molding material for a gas pipe. Next, the molding material was molded into a tube having an outer diameter of 20 mm, a wall thickness of about 3 mm, and a length of 100 mm by extrusion molding or the like. The obtained molded body was fired at 1300 to 1600 ° C. in the atmosphere to produce two tubular gas tubes (gas tubes 20 and 30 in FIG. 1).

<Preparation of paste-like sealing material>
Eight types of paste-like sealing materials having different MgO addition amounts were produced as follows.
First, SiO ₂ powder, Al ₂ O ₃ powder, Na ₂ CO ₃ powder, K ₂ CO ₃ powder, MgCO ₃ powder, CaCO ₃ powder and B ₂ O ₃ powder having an average particle diameter of about 1 μm to 10 μm, respectively, The following compounding ratio, that is, in terms of oxide, SiO ₂ is 67.0% by mass, Al ₂ O ₃ is 13.9% by mass, Na ₂ O is 8.5% by mass, K ₂ O is 9.1% by mass, MgO 0.6 wt%, CaO 0.8 _wt%, B 2 _{O 3} were mixed at the mixing ratio such that 0.1 wt%, to obtain a glass raw material powder.
Next, the glass raw material powder was melted in a temperature range of 1000 to 1500 ° C. (here, 1450 ° C.) to form glass (glassy intermediate).
The obtained glass (glassy intermediate) was pulverized to an average particle size of about 2 μm to produce a glass (glassy intermediate) powder.
MgO powder (average particle size: about 1 μm) is prepared, and the addition amount is changed within the range of 0 to 40% by mass with respect to the total mass of the glass raw material powder in terms of oxides. That is, 0, 1, 3, 5, 10, 20, 30, and 40% by mass (total 8 types) were added to the glass (glassy intermediate) powder and mixed well. The average particle diameter of the mixed powder at this time was about 1.5 μm. In this way, 8 types of mixed powders having different compositions with different amounts of the MgO powder (added later) were prepared.
The following treatment was performed as a crystallization treatment on the above eight kinds of mixed powders. First, the mixed powder is heated from room temperature to about 100 ° C. at a rate of temperature increase of about 1 to 5 ° C./min, and from about 100 ° C. at a rate of temperature increase of 1 to 10 ° C./min. After maintaining for about 30 to 60 minutes in a temperature range of ℃ (here, 850 ° C. ± 50 ° C.), it was cooled to room temperature at a rate of 1 to 5 ° C./min. In this way, a total of eight types of crystal-containing glasses having different MgO contents were prepared.

Here, in the crystal-containing glass to which MgO was not added, cristobalite crystals and / or leucite crystals were precipitated. In addition, among the remaining crystal-containing glasses to which MgO was added, forsterite crystals were precipitated so as to be dispersed in the glass matrix when the amount of MgO added later was 1 to 5% by mass. . As other crystals, cristobalite crystals and / or leucite crystals were precipitated. In the crystal-containing glass in which the amount of MgO added was 10% by mass, MgO crystals were also observed in addition to the forsterite crystals and the crystals. In the crystal-containing glass having an MgO addition amount of 20 to 40% by mass, MgO crystals are precipitated so as to be dispersed in the glass matrix, and at least one of cristobalite crystals, leucite crystals, and forsterite crystals is present. It was precipitated. It was also observed that the amount of MgO crystals increased as the amount of MgO added increased.
Next, the obtained eight types of crystal-containing glass were pulverized and classified to obtain powdery crystal-containing glass (that is, a sealing material) having an average particle size of about 2 μm.
40 parts by mass of each powdery crystal-containing glass (sealing material), 3 parts by mass of a general binder (here, ethyl cellulose was used) and 47 parts by mass of a solvent (here, terpineol was used). A total of 8 types of paste-like sealing materials were prepared by mixing.

<Joint treatment>
Joining processing was performed using the above-mentioned eight types of paste-like sealing materials. Specifically, as shown in FIG. 1, the two gas pipes 20, obtained on the both sides of the membrane element (corresponding to the oxygen separation membrane element 10 in FIG. 1) provided with the unfired coating film, 30 was placed. The gas pipe 20 is arranged at one end of the membrane element (end 15a of the oxygen separation membrane element 10 in the figure) and the gas pipe 30 is connected to the other end of the membrane element (oxygen separation membrane in the figure). The gas pipe 20 is brought into contact with one end surface of the porous substrate 12 in the membrane element (oxygen separation membrane element 10) to form a connection portion (connection surface 25). did. Similarly, the gas pipe 30 was brought into contact with the other end surface of the porous substrate 12 in the membrane element to form a connection portion (coupling surface 35).
Next, the gap between each of the coating pipe (corresponding to the oxygen separation membrane 14 in FIG. 1) and the gas pipes 20 and 30 in the membrane element (oxygen separation membrane element 10) sandwiched between the gas pipes 20 and 30 is closed. Then, the paste-like sealing material (sealing material 40 in the figure) was applied to the connecting surfaces 25 and 35. This was dried at 80 ° C. and then calcined in the atmosphere at 1200 ° C. for 2 hours. As a result, the oxygen separation membrane 12 having a film thickness of about 50 μm was formed on the outer peripheral surface 13 of the porous substrate 14, and the gas pipes 20, 30 and the oxygen separation membrane element 10 were joined to form the seal portion 40. . In this way, a joined body (oxygen separation membrane module 100) in which the gas pipes 20, 30 and the oxygen separation membrane element 10 were joined was constructed.
As described above, the oxygen separation membrane material (LSCN oxide or LSCT oxide) and the eight kinds of sealing materials having different addition amounts of MgO added to the vitreous intermediate powder are combined with each other for a total of ten types. The assembly (oxygen separation membrane module) was constructed. These joined bodies were designated as Samples 1 to 10. Table 1 shows the correlation between the samples 1 to 10, the material of the oxygen separation membrane, and the amount of MgO added to the sealing material.

<Gas leak test>
Next, for the oxygen separation membrane module 100 constructed as described above (samples 1 to 10 in which the oxygen separation membrane element 10 and the gas pipes 20 and 30 are joined), a leak test for confirming the presence or absence of a gas leak from the seal portion 40 is performed. went. Specifically, as shown in FIG. 1, the oxygen separation membrane element 10 is disposed in the internal space of the chamber 50, and the gas pipes 20, 30 penetrate the chamber 50, and the oxygen separation membrane element 10 and The oxygen separation membrane module 100 was accommodated so that the end on the joining side was disposed in the internal space of the chamber 50 and the other end was disposed outside the chamber 50. The boundary portion between the chamber 50 and the gas pipes 20 and 30 is sealed.
First, the temperature in the chamber 50 was set to 1200 ° C., and the oxygen separation membrane element 10 accommodated in the chamber 50 was heated to 1200 ° C. Under such temperature conditions, helium (He) gas was supplied into the chamber 50 at a flow rate of 100 mL / min under a pressure of 0.2 Pa. In addition, air was continuously supplied from the gas pipe 20 to the oxygen separation membrane element 10 at a flow rate of 100 mL / min under a pressure of 0.2 Pa for 2 hours. The air circulated through the hollow portion 17 having the inner diameter of the oxygen separation membrane element 10 and was discharged through the gas pipe 30. The composition of He exhaust gas discharged from an exhaust port (not shown) of the chamber 50 is measured by gas chromatography, and whether or not N ₂ in the air leaks from the seal portion 40 from the amount of N ₂ gas contained in the He exhaust gas. Was evaluated. Such an evaluation test was performed on samples 1 to 10.
The evaluation results of gas leak are shown in Table 1. In Table 1, those having a leak rate of N ₂ gas (volume content of N ₂ gas contained in He exhaust gas) of 1% or less are indicated as “none” and have practical airtightness It was. As shown in Table 1, in sample 1 in which the sealing material to which no MgO added to the vitreous intermediate powder was added was used, cracks were generated in the seal portion 40 and gas leaks were observed. Therefore, it was confirmed that the sealing material to which the MgO powder is not added is unsuitable for use in a high temperature range such as 1200 ° C. In Sample 8, gas leak was observed because the amount of MgO powder added was too large and the denseness of the seal portion 40 was insufficient. In the samples other than Samples 1 and 8, gas leakage at the seal portion 40 was preferably prevented regardless of the material of the oxygen separation membrane, and it was found that excellent airtightness and mechanical strength were obtained even at the high temperature. .

<Evaluation of thermal expansion coefficient after high temperature treatment>
Next, for the 10 types of oxygen separation membrane modules (samples 1 to 10) constructed as described above, after supplying air and He gas at a temperature of 1200 ° C. for 2 hours, The thermal expansion coefficient (however, an average value between room temperature (25 ° C.) and 500 ° C. based on the differential expansion method (TMA)) was measured. The results are shown in Table 1.
As shown in Table 1, Sample 1 had a thermal expansion coefficient lower than 10 × 10 ⁻⁶ K ⁻¹ . On the other hand, Samples 2 to 10 were all in the range of 10 × 10 ⁻⁶ K ^{−1 to} 14 × 10 ⁻⁶ K ⁻¹ . The thermal expansion coefficients of the oxygen separation membrane 14 made of LSCN oxide and LSCT oxide used here are 15 × 10 ⁻⁶ K ⁻¹ and 13 × 10 ⁻⁶ K ⁻¹ , respectively, and are made of MgO porous material. The thermal expansion coefficients of the base material 12 and the YSZ gas pipes 20 and 30 under the same conditions were 13.5 × 10 ⁻⁶ K ⁻¹ and 10.2 × 10 ⁻⁶ K ⁻¹ , respectively.

Moreover, the electrical conductivity in each seal | sticker part 40 of the said samples 1-10 was measured. That is, after applying a platinum paste serving as an electrode to the seal part 40 of each sample, a platinum wire for connecting the current terminal and the voltage terminal to the electrode part is attached and baked at 850 to 1100 ° C. for 10 to 60 minutes, In a device that can be adjusted to an arbitrary temperature, the electrical conductivity (conductivity) at 1200 ° C. was measured using a DC four-terminal method. As a result, in all the above samples, the conductivity was an undetectable level of 10 ⁻⁷ S / cm or less. Thereby, the insulation in the seal | sticker part of each said samples 1-10 (namely, oxygen separation membrane module) was confirmed.

  From the above results, according to the present example, the glass matrix contains a forsterite crystal and a sealing material comprising a crystal-containing glass that can contain a cristobalite crystal and / or a leucite crystal, or the forsterite, cristobalite, leucite. A dense oxygen separation membrane made of a perovskite oxide and a zirconia-based oxide formed on a porous MgO substrate using a sealing material made of crystal-containing glass containing MgO crystals in addition to at least one of the crystals By joining and connecting the oxygen separation membrane element and the gas pipe so as to block the dense gas pipe made of the material (YSZ), even if exposed to a high temperature condition of at least 1200 ° C., no gas leakage occurs. Joining while ensuring sufficient airtightness and mechanical strength (i.e. Forming a pole tip) it was. For this reason, a high-performance oxygen separation membrane module excellent in heat resistance can be realized.

DESCRIPTION OF SYMBOLS 10 Oxygen separation membrane element 12 Porous base material 13 Outer peripheral surface 14 Oxygen separation membrane 15a, 15b End part of axial direction of oxygen separation membrane element 20 Gas pipe 25 Connection surface 30 Gas pipe 35 Connection surface 40 Seal part (seal material)
50 chamber 100 oxygen separation membrane module

Claims (11)

An oxygen separation membrane element comprising an oxygen separation membrane made of an oxide ceramic of a perovskite structure which is an oxygen ion conductor on a porous substrate;
An oxygen separation membrane module comprising a ceramic connecting member joined to the oxygen separation membrane element,
A seal portion that blocks gas flow at the joint portion is formed at the joint portion between the oxygen separation membrane element and the connection member,
The seal portion is formed of glass in which at least forsterite crystals are precipitated in a glass matrix,
The glass has the following six constituent elements, and the following six mass elements in terms of oxides are defined as 100% by mass as a whole.
SiO ₂ 60 to 78 wt%;
Al ₂ O ₃ 10~22% by weight;
Na ₂ O 3-16% by mass;
K ₂ O 5-16% by mass;
CaO 0 to 4% by mass;
B ₂ O _{30 to} 4% by mass;
And have
Here, the glass further contains Mg as a constituent element, and the mass composition of MgO is 1% by mass or more and less than 13% by mass with respect to 100% by mass of the whole glass in terms of oxide, and at least of these An oxygen separation membrane module, in which half of the amount is present as a constituent of crystals precipitated in the glass matrix. An oxygen separation membrane element comprising an oxygen separation membrane made of an oxide ceramic of a perovskite structure which is an oxygen ion conductor on a porous substrate;
An oxygen separation membrane module comprising a ceramic connecting member joined to the oxygen separation membrane element,
A seal portion that blocks gas flow at the joint portion is formed at the joint portion between the oxygen separation membrane element and the connection member,
The seal portion is formed of glass in which a crystal made of magnesium oxide (MgO) and at least one crystal selected from cristobalite crystal, leucite crystal and forsterite crystal are precipitated in a glass matrix. ,
The glass has the following six constituent elements, and the following six mass elements in terms of oxides are defined as 100% by mass as a whole.
SiO ₂ 60 to 78 wt%;
Al ₂ O ₃ 10~22% by weight;
Na ₂ O 3-16% by mass;
K ₂ O 5-16% by mass;
CaO 0 to 4% by mass;
B ₂ O _{30 to} 4% by mass;
And have
Here, the glass further contains Mg as a constituent element, and the mass composition of MgO is 13% by mass or more and 30% by mass or less with respect to 100% by mass of the whole glass in terms of oxide, and at least of these An oxygen separation membrane module in which half of the amount is present as a constituent component of crystals precipitated in the glass matrix. The glass constituting the seal part maintains a thermal expansion coefficient of 10 × 10 ⁻⁶ K ^{−1 to} 14 × 10 ⁻⁶ K ⁻¹ even when exposed to a temperature of at least 1200 ° C. 3. 2. An oxygen separation membrane module according to 1. The oxygen separation membrane has the general formula:
Ln _1-x A _x MO _3-δ (1)
(However, Ln in the formula is at least one selected from lanthanoids, A is at least one selected from the group consisting of Sr, Ca and Ba, and M may constitute a perovskite structure. 2 or more kinds of metal elements, 0 ≦ x <1, and δ is a value determined so as to satisfy the charge neutrality condition.) Constructed by oxide ceramics having a perovskite structure Has been
The oxygen separation membrane module according to claim 1, wherein the connection member is made of stabilized zirconia. An oxygen separation membrane comprising an oxygen separation membrane element comprising an oxygen separation membrane made of an oxide ceramic having a perovskite structure as an oxygen ion conductor on a porous substrate, and a ceramic connecting member joined to the oxygen separation membrane element A sealing material for sealing and joining the oxygen separation membrane element and the connecting member in a module,
The following six constituent elements are represented by the following mass composition with the total of the six constituent elements being 100% by mass in terms of oxides:
SiO ₂ 60 to 78 wt%;
Al ₂ O ₃ 10~22% by weight;
Na ₂ O 3-16% by mass;
K ₂ O 5-16% by mass;
CaO 0 to 4% by mass;
B ₂ O _{30 to} 4% by mass;
It is mainly a glass having at least forsterite crystals precipitated in a glass matrix,
Here, the glass further contains Mg as a constituent element, and the mass composition of MgO is 1% by mass or more and less than 13% by mass with respect to 100% by mass of the whole glass in terms of oxide, and at least of these Half of the amount is a sealing material for an oxygen separation membrane module, which is present as a constituent component of crystals precipitated in the glass matrix. In an oxygen separation membrane module comprising an oxygen separation membrane element comprising an oxygen separation membrane made of an oxide ceramic having a perovskite structure as an oxygen ion conductor on a porous substrate, and a ceramic connecting member joined to the membrane element A sealing material for sealing and joining the oxygen separation membrane element and the connecting member,
The following six constituent elements are represented by the following mass composition with the total of the six constituent elements being 100% by mass in terms of oxides:
SiO ₂ 60 to 78 wt%;
Al ₂ O ₃ 10~22% by weight;
Na ₂ O 3-16% by mass;
K ₂ O 5-16% by mass;
CaO 0 to 4% by mass;
B ₂ O _{30 to} 4% by mass;
The glass mainly comprises a glass in which a crystal made of magnesium oxide (MgO) and at least one crystal selected from a cristobalite crystal, a leucite crystal and a forsterite crystal are precipitated in a glass matrix. ,
Here, the glass further contains Mg as a constituent element, and the mass composition of MgO is 13% by mass or more and 30% by mass or less with respect to 100% by mass of the whole glass in terms of oxide, and at least of these Half of the amount is a sealing material for an oxygen separation membrane module, which is present as a constituent component of crystals precipitated in the glass matrix. Are prepared as the thermal expansion coefficient after exposure to a temperature of at least 1200 ° C. to maintain the ^{10 × 10 -6 K -1 ~14 ×} 10 -6 K -1, according to claim 5 or 6 Sealing material for oxygen separation membrane module. A method for producing a sealing material for an oxygen separation membrane module,
The following composition in mass ratio in terms of oxide:
SiO ₂ 60 to 75 wt%;
Al ₂ O ₃ 10-20% by mass;
Na ₂ O 3-15% by mass;
K ₂ O 5-15% by mass;
CaO 0 to 3% by mass;
B ₂ O _{30 to} 3% by mass;
MgO 0 to 3% by mass;
A glass raw material powder prepared so as to be substantially constituted from the above, and melting the raw material powder to prepare a glass;
After pulverizing the prepared glass, adding MgO powder in an amount corresponding to 1% by mass or more and less than 10% by mass of the entire glass raw material powder to prepare a mixed powder of the glass and the MgO; and
Crystallizing the mixed powder to precipitate at least forsterite crystals as crystal components in the glass matrix;
Manufacturing method. A method for producing a sealing material for an oxygen separation membrane module,
The following composition in mass ratio in terms of oxide:
SiO ₂ 60 to 75 wt%;
Al ₂ O ₃ 10-20% by mass;
Na ₂ O 3-15% by mass;
K ₂ O 5-15% by mass;
CaO 0 to 3% by mass;
B ₂ O _{30 to} 3% by mass;
MgO 0 to 3% by mass;
A glass raw material powder prepared so as to be substantially constituted from the above, and melting the raw material powder to prepare a glass;
After pulverizing the prepared glass, MgO powder is added in an amount corresponding to 10% by mass or more and 30% by mass or less of the entire glass raw material powder to prepare a mixed powder of the glass and the MgO; and
By crystallizing the mixed powder, a crystal composed of magnesium oxide (MgO) as a crystal component in the glass matrix, and at least one crystal selected from a cristobalite crystal, a leucite crystal, and a forsterite crystal, Precipitating,
Manufacturing method.   The manufacturing method according to claim 8 or 9, wherein, as the crystallization treatment, the mixed powder is heated for a predetermined time in a temperature range in which crystallization of 1000 ° C or less can be induced. An oxygen separation membrane module comprising an oxygen separation membrane element comprising an oxygen separation membrane made of an oxide ceramic having a perovskite structure as an oxygen ion conductor on a porous substrate, and a ceramic connecting member joined to the membrane element A method of manufacturing comprising:
Providing a membrane element in which a coating film is formed by coating an oxygen separation membrane material made of oxide ceramics of the perovskite structure on the porous substrate;
Preparing the ceramic connection member;
A sealing material according to any one of claims 5 to 7, wherein the sealing material is made of glass in which crystals containing at least Mg as a constituent element are precipitated in a glass matrix. By applying the material and the connecting member to the connected part, and by firing the membrane element and the connecting member, which are connected to each other by being provided with the sealing material, in the firing temperature range of the coating film, An oxygen separation membrane formed by firing the coating film is formed on the porous base material, and a seal portion that blocks gas flow made of the sealing material is formed at a connection portion between the membrane element and the connection member. To join each other at the same time,
The manufacturing method of the oxygen separation membrane module including this.

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