JP2006082039A - Oxygen separation membrane element, its manufacturing method, oxygen manufacturing method, and reactor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an oxygen separation membrane element more enhanced in oxygen permeation velocity, its manufacturing method, an efficient oxygen manufacturing method using oxygen separation membrane element or a reactor. <P>SOLUTION: Since catalyst layers 18 and 20 are formed in uniform film thickness by transfer and a crack or peeling is hard to occur even if the catalyst layers 18 and 20 are made thick, the oxygen separation membrane element 10 more increased in oxygen permeation velocity is obtained by increasing the supporting thickness of the catalyst layers 18 and 20. Moreover, since catalyst particles 21 are uniformly and densely arranged in the catalyst layers 18 and 20 formed by transfer, the catalyst layers 18 and 20 become large in support quantity even in the same film thickness as compared with catalyst layers 50 and 52 formed by the direct coating of a slurry or the like and there is an advantage capable of obtaining a high oxygen permeation speed. Further, there is no trouble that the number of supporting processes are increased like a CVD method or the like and there is an advantage of having no necessity for altering printing conditions such as a predetermined machine, a printing plate, the preparation of paste and the like corresponding to the shape or size of an oxygen separation membrane ready to form the catalyst layers 18 and 20 like direct predetermined. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an oxygen separation membrane element for selectively permeating oxygen, a manufacturing method thereof, and use thereof.

  Provided with a dense oxygen separation membrane having oxygen ion conductivity, oxygen is dissociated from the gas on one surface side and ionized oxygen ions are recombined on the other surface side, so that oxygen is selectively transferred from the one surface to the other surface. Oxygen separation membrane elements are known for permeation and separation from the gas. According to such an oxygen separation membrane element, oxygen can be easily separated from a gas containing oxygen. Therefore, by using this, for example, a cryogenic separation method, a PSA (pressure fluctuation adsorption) method, or the like can be used. An alternative and inexpensive method for producing oxygen can be provided. In particular, in the case where the oxygen separation membrane is composed of an electron-oxygen ion mixed conductor, the oxygen separation membrane itself has electron conductivity, so that an external electrode and an external circuit for short-circuiting one surface and the other surface are unnecessary. In addition, there is an advantage that a high oxygen transmission rate can be obtained by increasing the moving speed of oxygen ions by the potential difference between both surfaces (see, for example, Patent Documents 1 and 2).

  In the above oxygen separation membrane element, a catalyst layer is formed on at least one of the oxygen dissociation side and the other surface of the oxygen recombination side of the oxygen separation membrane, preferably both, thereby increasing the oxygen separation rate. It has been broken. A dissociation catalyst layer for promoting oxygen dissociation and ionization is provided on the oxygen dissociation side, and a recombination catalyst layer for promoting recombination is provided on the oxygen recombination side. This increases the oxygen dissociation rate and ionization rate (hereinafter collectively referred to as ionization rate) or the recombination rate, thereby increasing the oxygen separation rate.

The oxygen separation membrane element as described above can be used as a reactor for an oxidation reaction apparatus such as a partial oxidation reaction of hydrocarbons. For example, if a gas containing hydrocarbon such as methane (CH ₄ ) is supplied to the other side of the oxygen separation membrane, the hydrocarbon can be oxidized by the permeated oxygen ions. Therefore, it can be used for GTL (Gas to Liquid: a technology for synthesizing liquid fuel from natural gas by chemical reaction), production of hydrogen gas for fuel cells, and the like. Even in such a utilization mode, the reaction is promoted by providing a catalyst layer or increasing the oxygen transmission rate using an electron-oxygen ion mixed conductor.
Japanese Patent Laid-Open No. 2003-190792 JP 2003-225567 A Japanese Patent Laid-Open No. 2003-092113 JP 2003-151878 A

  By the way, the catalyst layer as described above has been conventionally formed by preparing a slurry or paste in which catalyst powder is mixed with a solvent or the like, and dip-coating or printing on the oxygen separation membrane. However, in order to increase the oxygen permeation rate by increasing the chance of contact with gas and oxygen ions, it is desired to make the catalyst layer sufficiently thick even though it is desired to make the catalyst layer as thick as possible. It was difficult.

  For example, in the case of dip coating, the thicker the thickness is, the more easily the variation occurs. Therefore, the shrinkage variation may occur when the solvent and the binder are volatilized or removed during the drying and firing processes. Further, in general, the catalyst particle of the oxygen separation membrane has a specific surface area of particles because the average particle size is a number (μm), that is, fine particles within a range of 1 to 10 (preferably 2 to 5) (μm). Therefore, the density of the catalyst layer is lowered and the grain boundary portion is increased in the layer. Therefore, for example, when the film thickness is 30 (μm) or more, cracks and peeling are likely to occur during drying and firing. Therefore, although the film thickness to be formed at one time is thinned and multilayered, the catalyst layer does not become a perfect dense body even when fired, so an uneven interface tends to occur between the layers, There is an inconvenience that peeling at the interface tends to occur. That is, it is difficult to obtain a thick catalyst layer of 0.1 (mm) or more as described in Patent Documents 1 and 2 by dip coating. In addition, when the oxygen separation membrane is configured in a long cylindrical shape or the like, there is a problem that the dried state after application is likely to be non-uniform, and a difference in film thickness due to the site occurs, so that cracks and peeling are more likely to occur. .

  On the other hand, in the case of printing, if the printing is performed on a flat surface, it is easy to obtain the uniformity of the film thickness as compared with the dip coating. However, in order to perform appropriate printing, it is necessary to change printing conditions such as a printing press, a printing plate, and paste preparation according to the shape and size of the oxygen separation membrane on which the catalyst layer is to be formed. As the thickness increases, the appropriate range of printing conditions also decreases. For this reason, the management of the manufacturing process becomes extremely complicated, and it is difficult to ensure optimization across a variety of products, that is, to ensure film thickness uniformity. For example, when the formation surface of the catalyst layer is a curved surface as in the case where the oxygen separation membrane is formed in a cylindrical shape or the like, it is difficult to apply the paste with a uniform film thickness using a printing method. . Therefore, in any case, there is a problem that cracks and peeling are likely to occur as in the case of dip coating. As a method for forming the catalyst layer, a CVD (chemical vapor deposition) method, an electrophoresis method, an ion plating method, a vacuum vapor deposition method, etc. have been proposed, but the composition control is difficult and the shape of the oxygen separation membrane is limited. Moreover, since there are problems such as an increase in the number of processes, practical use has not been achieved.

  Therefore, the present inventors conducted extensive research to develop a catalyst layer forming method that replaces the conventional method for the purpose of obtaining a higher oxygen transmission rate. It has been found that it has significantly higher properties. Incidentally, Patent Documents 3 and 4 describe that in a solid oxide fuel cell, a fuel electrode film and an electronic conductive layer therein are provided by transfer. These are only intended to increase the adhesion between the solid electrolyte and the fuel electrode membrane, and do not suggest applicability to oxygen separation membranes. It does not give any knowledge about whether the characteristics can be obtained.

  The present invention has been made on the basis of the above knowledge, and its purpose is to provide an oxygen separation membrane element having a higher oxygen permeation rate, a production method thereof, and an efficient oxygen production method and reaction using the same. Is to provide a vessel.

  The gist of the method for producing an oxygen separation membrane element of the first invention for achieving such an object is to provide a dense oxygen separation membrane having oxygen ion conductivity, an oxygen dissociation side surface, and an oxygen regenerating side. A catalyst layer is provided on at least one of the other surfaces of the bonding side, and oxygen is dissociated from the gas on one surface side and ionized oxygen ions are recombined on the other surface side, whereby oxygen is selectively transferred from the one surface to the other surface. A method for producing an oxygen separation membrane element for permeation and separation from the gas, wherein (a) a catalyst particle layer provided on a predetermined mount is transferred to the oxygen separation membrane to thereby form the catalyst layer. It is to form.

  Further, the gist of the oxygen separation membrane element of the second invention for achieving the above object is to provide a dense oxygen separation membrane having oxygen ion conductivity, one side of the oxygen dissociation side and the oxygen recombination side A catalyst layer is provided on at least one of the other surfaces, and oxygen ions dissociated from the gas on one surface side and ionized oxygen ions are recombined on the other surface side, thereby allowing oxygen to selectively permeate from one surface to the other surface. And (a) the catalyst layer is formed by transfer.

  Further, the gist of the oxygen production method of the third invention is that the oxygen separation membrane element of the second invention is used, and a source gas containing oxygen is supplied to the one surface side and oxygen separated from the source gas is supplied. Is to be recovered from the other side.

  The gist of the reactor of the fourth invention is that (a) the oxygen separation membrane element of the second invention and (b) a gas containing oxygen is supplied to one surface side of the oxygen separation membrane element. A first gas supply path; (c) a second gas supply path for supplying a gas containing a predetermined compound to the other surface side; and (d) a reaction between oxygen and the predetermined compound on the other surface side. And a gas recovery path for recovering the generated gas.

  According to the first and second inventions, since the catalyst layer is formed with a uniform film thickness by transfer, cracks, peeling, and the like hardly occur even when the film thickness is increased. Therefore, an oxygen separation membrane element having a higher oxygen transmission rate can be obtained by increasing the thickness of the catalyst layer in accordance with desired characteristics. In addition, the catalyst layer formed by transfer provides a high oxygen transmission rate even at the same film thickness as compared to that formed by direct application of slurry or the like, and it is easy to increase the area and shape of the supported surface. That is, there are various advantages such as the shape of the oxygen separation membrane being free and the patterning of the catalyst layer being easy, and there is no inconvenience of increasing the number of supporting steps as in the CVD (chemical vapor deposition) method. In addition, as in the case of direct printing, there is no need to change printing conditions such as a printing press, a printing plate, and a paste preparation according to the shape and size of the oxygen separation membrane on which the catalyst layer is to be formed. It is also possible to manufacture a transfer paper having a large constant area and cut it into an appropriate size. The reason why the oxygen permeation rate is increased as compared with direct coating as described above is based on the fact that the catalyst particles are uniformly arranged in the case of transfer. The higher the homogeneity of the arrangement, the smaller the voids between the particles, so that the amount of support increases even with the same film thickness. As a result, the contact area with the oxygen separation membrane surface increases and oxygen The transmission speed is increased. The “predetermined mount” is sufficient if it can be temporarily fixed by applying a constituent material of a transfer paper such as a release layer or a catalyst particle layer. In this application, in addition to paper, a PET film Such a resin material is also included.

  Incidentally, in the oxygen separation membrane element, since the catalyst layer is formed on the dense oxygen separation membrane, the solvent component in the slurry is hardly sucked into the oxygen separation membrane in the membrane formation by dip coating. Therefore, the coated slurry is in a state of adhering to the surface of the oxygen separation membrane due to its viscosity while maintaining fluidity, so that the slurry itself flows according to gravity and the catalyst particles also flow according to gravity in the slurry. Therefore, not only the film thickness becomes nonuniform in the dip coating, but also the arrangement of the catalyst particles becomes nonuniform. On the other hand, when the catalyst is supported by transfer, the catalyst layer and the catalyst particles cannot flow, so that the film thickness and the arrangement of the catalyst particles become uniform.

  According to the second invention, when a source gas containing oxygen is supplied to the one surface side of the oxygen separation membrane element as described above, oxygen therein is selectively ionized and permeated through the oxygen separation membrane. Since it is recombined and recovered on the other side, oxygen in the raw material gas is efficiently separated, so that oxygen can be produced at low cost and high efficiency.

  According to the third aspect of the invention, the oxygen separation membrane element as described above is provided, and a gas containing oxygen from the first gas supply path to the one surface side is predetermined from the second gas supply path to the other surface side. Each of the gases containing the compound is supplied, and the gas generated by the reaction between oxygen and the predetermined compound is recovered from the gas recovery path. Therefore, since the oxygen permeation rate is increased by increasing the ionization rate or recombination rate of oxygen, the reaction efficiency with a predetermined compound in the gas supplied to the other surface side is increased, so that high efficiency is achieved. A reactor is obtained.

  In the present invention, the term “dense oxygen separation membrane” means that the oxygen separation membrane has a structure that does not allow gas molecules in the atmosphere to which the oxygen separation membrane is exposed to permeate in the thickness direction as it is when the oxygen permeable membrane element is used. It means that you are doing. That is, the preciseness mentioned here is not uniquely determined, and it is sufficient if it has the above-described characteristics in the intended use mode.

  Here, preferably, the catalyst layer has a large number of protrusions arranged on the surface thereof at a constant center interval along one direction. In this way, regular protrusions and depressions are provided on the surface of the catalyst layer by the protrusions, so that the surface area, that is, the contact area between the gas and the catalyst layer on one surface or the other surface on which the catalyst layer is provided increases. However, since it is a regular unevenness, its surface area is remarkably increased as compared with the case where irregular protrusions in size and arrangement direction are provided. Therefore, in addition to the increase in the thickness of the catalyst layer, the ionization rate or the recombination rate is increased according to the amount of increase in the surface area, so that the rate of at least the rate-limiting factor can be increased. As described above, the projection formation surface is set to one or both, and the size and the mutual interval are determined in consideration of the balance between the above speeds and the ion transport speed in the oxygen separation membrane, thereby increasing the oxygen transmission rate. Can do. In addition, when the above protrusions are provided, the thickness dimension of the catalyst layer on the oxygen separation membrane is not uniform. However, since the film formed by transfer has already been volatilized on the transfer paper, the shrinkage during drying and firing is suppressed, so that it is easy to provide unevenness without causing cracks and the like. is there.

  For example, in the case where a large number of protrusions are provided on the one surface side, the contact area between the dissociation catalyst layer surface and the gas containing oxygen is significantly increased as compared with the conventional case, so that the ionization rate of oxygen is significantly increased. In the case where a large number of protrusions are provided on the other surface side, the area of the recombination catalyst layer, that is, the area where oxygen recombination is performed is remarkably increased, so that the recombination rate of oxygen ions is remarkably increased. That is, the reaction is promoted by regularly arranging a large number of protrusions of uniform size on one side and the other side. In addition, the oxygen permeation rate and the like can be improved by providing regular projections so that the gas supplied toward the catalyst layer surface is subjected to uniform flow resistance over the entire surface, and the regular unevenness. It is considered that this is because, by flowing in one direction along the formed straight groove, a uniform flow rate is obtained near the surface of the oxygen separation membrane and a rectifying effect is obtained. That is, since the gas supplied toward one surface or the other surface of the oxygen separation membrane element is uniformly brought into contact with the entire surface, it is estimated that the entire surface is effectively used, thereby improving the efficiency. The

  Preferably, the plurality of protrusions have a rectangular cross section along at least one of the first direction and the second direction. That is, a groove having a rectangular cross-sectional shape is provided between a large number of protrusions. The shape of the protrusion can be arbitrarily determined as long as it is provided with a substantially uniform size and shape on the entire surface, and may be various shapes such as a rhombus, a triangle, a hexagon, and a circle in plan view, Further, a groove having a semi-circular or semi-circular cross section may be formed between the protrusions, but in this way, the cross-sectional shape is a wavy shape, that is, a shape in which the side surface of the protrusion is gently inclined. Compared with the case where it comprises, the surface area of an oxygen separation membrane element can be made still larger. The plurality of protrusions more preferably form a rectangle in plan view, and more preferably form a square.

  Preferably, the catalyst layer has a thickness dimension of 100 (μm) or more. In this way, since the catalyst layer is sufficiently thick, a higher oxygen transmission rate can be obtained. Incidentally, when the present inventors evaluated the relationship between the thickness dimension of the catalyst layer formed by transfer and the oxygen permeation rate, the permeation rate is remarkably increased as the thickness dimension increases with a relatively thin catalyst layer thickness. Although a tendency was observed, this tendency was almost saturated at about 100 (μm), and it was confirmed that a transmission rate comparable to that at 100 (μm) was maintained in the range up to at least about 300 (μm). It was.

  Preferably, the oxygen separation membrane is a mixed conductor having oxygen ion conductivity and electron conductivity. In this way, oxygen ions can be continuously transmitted between them without using an external electrode or an external circuit for short-circuiting the one surface and the other surface, and the moving speed of the oxygen ions is increased. Therefore, there is an advantage that the oxygen transmission rate can be further increased.

Preferably, the oxygen separation membrane has a general formula Ln _1-x Ae _x MO ₃ (where Ln is a lanthanoid, Ae is one or a combination of two or more selected from Ba, Sr, and Ca, M is Fe, Mn, Ga, Ti, Co, Zr, Ce, Mg, Ge, Zn, Cu, Sc, V, Cr, Ni, Y, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, One or a combination of two or more selected from Sb, Pb, Bi, Po, Al, In, and Sn, composite compounds represented by 0 ≦ x ≦ 1), ZrO ₂ oxides, CeO ₂ oxides It consists of one or a combination of two or more selected from among products. Since these compounds are both dense and have a high oxygen transmission rate, they are suitable as the oxygen separation membrane material of the present invention.

Preferably, the oxygen separation membrane is Ce _2-x Zr _x O _4-σ (where 0 <x <2, 0 ≦ σ ≦ 4), CeGd oxide, CeSm oxide, Ba (CaNb) _It consists of one or a combination of two or more selected from _two oxides, BiVCu oxides, and ZrO ₂ oxides. These compounds are also preferable because they are dense and have a high oxygen transmission rate. In particular, with Ce-based materials, the movement of oxygen ions in a reducing atmosphere is expected to increase. More preferably, the oxygen separation membrane is made of a material containing one or a combination of two or more selected from MgO, Al ₂ O ₃ and Y ₂ O ₃ . Films made of these materials have the advantage of having a relatively high strength.

  Preferably, the oxygen separation membrane is made of a material containing a metal or metal oxide having electron conductivity. In this case, the metal or metal oxide imparts electron conductivity to the oxygen separation membrane or further enhances the electron conductivity, so that the transmission rate of oxygen ions is further increased, and consequently the transmission rate. There is an advantage that can be increased.

  Preferably, the oxygen separation membrane is provided on the porous support so as to cover the entire surface. This porous support may be located on either the one side or the other side of the oxygen separation membrane. In this way, since the gas can easily pass through the inside of the porous support, by configuring the porous support to have an appropriate thickness dimension, the oxygen separation membrane element machine is not affected without affecting the oxygen transmission rate. Can increase the mechanical strength. Moreover, since the mechanical strength of the oxygen separation membrane element is ensured by the porous support, it becomes possible to reduce the thickness dimension of the oxygen separation membrane to such an extent that the oxygen transmission rate is not limited by the film thickness, The effect of improving the permeation speed by increasing the surface area can be obtained more remarkably. In the case where such a porous support is provided, when a dissociation catalyst layer or a recombination catalyst layer is further provided, one is on the surface of the oxygen separation membrane and the other is the oxygen separation membrane and the porous support. The other side may be provided on the surface of the porous support, preferably in a state of being permeated therewith.

  In the above embodiment, “covering the entire surface” means that one surface of the porous support is the same as the surface of the oxygen separation membrane on the side opposite to the porous support when the oxygen separation membrane element is used. It means not being exposed to space. For example, even if one surface of a porous support provided with an oxygen separation membrane in a non-use state is partially exposed, such a mode can be used as long as that part is covered by an apparatus or the like during use. It is included in the above “covering the entire surface”.

Preferably, the porous support has the general formula Ln _1-x Ae _x MO ₃ (where Ln is a lanthanoid, Ae is one or a combination of two or more selected from Ba, Sr, and Ca) , M is Fe, Mn, Ga, Ti, Co, Zr, Ce, Mg, Ge, Zn, Cu, Sc, V, Cr, Ni, Y, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd , Sb, Pb, Bi, Po, Al, In, Sn selected from one or a combination of two or more, a composite compound represented by 0 ≦ x ≦ 1), ZrO ₂ oxide, CeO ₂ It is composed of one or a combination of two or more selected from oxide, magnesium oxide (MgO), aluminum oxide (Al ₂ O ₃ ), silicon nitride (Si ₃ N ₄ ), and silicon carbide (SiC). . The material of the porous support is not particularly limited, but by doing so, the difference in thermal expansion from the film material is reduced, and film peeling and the like are further suppressed.

  Preferably, the oxygen separation membrane and the porous support are made of the same material. In this way, since the thermal expansion coefficients of the two coincide with each other, even when heated or cooled during the manufacturing process or in use, damage due to the difference in thermal expansion amount is suitably suppressed.

Preferably, the oxygen separation membrane and the porous support are made of materials having different compositions. Since the strength of the entire oxygen separation membrane element must be ensured by the support, the required properties of the support and the oxygen separation membrane are different. For example, when the required strength is relatively high, oxygen separation is required. It is desirable that the membrane and the support are made of different materials. In addition, in the case where only the membrane side is in a reducing atmosphere (for example, when CH ₄ is flowed), the oxygen separation membrane may be reduced and expanded. It is preferable to relatively increase the thermal expansion.

  Preferably, the porous support has an average pore diameter r in the range of 0.1 <r <20 (μm) and a porosity p in the range of 5 <p <60 (%). This range is preferable in order to suppress the decrease in the oxygen permeation rate and increase the strength of the oxygen separation membrane element as much as possible. If the pore diameter and the pore diameter are too small, the gas permeation resistance of the porous support increases, so even if the oxygen separation membrane is made thin, the porous support becomes a rate-limiting factor, so the oxygen permeation rate is remarkably high. descend. On the other hand, if the pore diameter and the pore diameter are too large, the mechanical strength is lowered and the function as a support is lost.

  Preferably, the plurality of protrusions are fine protrusions having a height dimension in a range of 5 to 1000 (μm) and a center interval in a range of 5 to 1000 (μm). In order to maintain the strength of the protrusion and not to disturb the gas rectifying property, it is preferable to have such a size. More preferably, the height dimension is in the range of 10 to 500 (μm), and the center distance is in the range of 10 to 500 (μm). For example, the height dimension is preferably about 100 (μm), and the center interval (pitch) is preferably about 150 (μm).

Preferably, the dissociation catalyst layer is a La-Sr-Co-based oxide, a La-Sr-Mn-based oxide, or a platinum-based element. More preferably, it is made of La _x Sr _1-x CoO ₃ (0 <x <1, preferably x = 0.6). According to such a catalyst, oxygen in the gas supplied to the one surface side of the oxygen separation membrane is suitably ionized, permeated through this, and guided to the other surface side. In addition to the above materials, the catalyst layer is composed of Sm _x SrCoO ₃ (0 <x <1, preferably x = 0.5), La _1-x Sr _x MnO ₃ (0 <x <1, preferably x = 0.15), La _1-x Sr _x Co _1-y Fe _y O ₃ (0 <x <1, 0 <y <1, preferably x = 0.9, y = 0.1) are also preferably used. In addition, the dissociation catalyst layer can also be comprised with the same material as an oxygen separation membrane, and in that case, a dissociation catalyst layer can be comprised with a part of the oxygen separation membrane.

  Preferably, the recombination catalyst layer includes Ni, Co, Ru, Rh, Pt, Pd, Ir, and the like. Preferably, it is made of Ni formed by reducing NiO. According to such a catalyst, oxygen ions guided to the other surface side of the oxygen separation membrane are suitably recombined, and oxygen is recovered from the other surface side. In addition, even when the dissociation catalyst layer and the recombination catalyst layer are made of any of the materials described above, oxygen can permeate through the grain boundaries or the inside of the grains, so that a porous catalyst layer is formed as well as a porous layer. Can do.

  Preferably, the oxygen separation membrane has a thickness dimension in a range of 50 to 5000 (μm) in an aspect in which the porous support is not provided, and the porous support In the embodiment in which the body is provided, the body has a thickness dimension of 1000 (μm) or less. In this way, since the film thickness of the oxygen separation membrane is sufficiently thin as long as the mechanical strength of the oxygen separation membrane element can be ensured, it is suitably suppressed that the rate of oxygen permeation is limited and is high. It becomes easy to obtain the oxygen transmission rate. If the porous support is not provided, it is necessary that the oxygen separation membrane itself has sufficient mechanical strength, so that it is necessary to have a thickness greater than or equal to the above thickness. In this case, since the mechanical strength of the oxygen separation membrane itself is not required, it is desirable to make it as thin as possible. Note that there is no particular lower limit on the thickness dimension of the oxygen separation membrane as long as its denseness is maintained.

Further, the oxygen separation membrane element, other such partial oxidation reactions of oxygen production or hydrocarbons as described above, by supplying the NO _x on one side, it can also be used for the reduction.

  Preferably, the oxygen separation membrane is a flat plate as a whole. Further, in the aspect in which the catalyst layer is provided, the dissociation catalyst layer is provided on one surface, and the recombination catalyst layer is provided on the other surface. With such a shape, it is easy to form the fine protrusions on one surface and the other surface. In an aspect in which such a plate-like oxygen separation membrane is provided on a porous support and a catalyst layer is provided, after the catalyst layers are provided on both sides of the separately formed oxygen separation membrane, the porous support is provided. Alternatively, an oxygen separation membrane element is produced by sequentially forming one catalyst layer, an oxygen separation membrane, and the other catalyst layer on a porous support. Examples of the flat plate shape include a disk shape and a rectangular plate shape.

  Preferably, the oxygen separation membrane has a cylindrical shape with one end closed. In an embodiment in which a catalyst layer is provided, one of the inner peripheral surface and the outer peripheral surface is provided with the dissociation catalyst layer. It corresponds to the one surface, and the other corresponds to the other surface provided with the recombination catalyst layer. The oxygen separation membrane is not limited to a flat one, and may be such a three-dimensional one. In the aspect in which the gas is supplied to the inner peripheral surface side, for example, a gas introduction tube may be inserted inside the cylindrical oxygen separation membrane and the gas may be supplied from the tip.

  Preferably, the porous support has a cylindrical shape with one end closed, and the oxygen separation membrane or the two kinds of catalyst layers and the oxygen separation membrane are sequentially laminated on the inner peripheral surface or the outer peripheral surface thereof. Is provided. In this way, the mechanical strength can be ensured by the porous support even in an aspect in which the oxygen separation membrane element has a cylindrical shape.

  Preferably, the oxygen separation membrane element comprises: (a) a porous membrane prepared separately in a slurry containing the constituent material of the oxygen separation membrane (dip); (B) a baking step for forming the oxygen separation membrane by baking the separation membrane slurry layer at a predetermined temperature and sintering it on the porous support; and (c) the oxygen A transfer step in which a transfer paper coated with a constituent material of the catalyst layer is attached to the surface of the separation membrane and subjected to a firing treatment to form a catalyst layer on the surface of the oxygen separation membrane. . In this way, since the catalyst layer is formed by attaching the transfer paper to the oxygen separation membrane and firing, the catalyst layer having a uniform desired thickness can be easily formed. The slurry for forming the oxygen separation membrane contains a solvent such as water, a binder, a dispersant and the like in addition to the constituent materials.

  The dipping process can be repeated an appropriate number of times until a slurry layer having a predetermined thickness is formed. Moreover, when forming the said oxygen separation membrane, a drying process is performed as needed before performing a baking process. This drying treatment may be repeated, for example, alternately with the dipping step or at any time.

  Preferably, the transfer paper comprises (a) a step of forming a release layer on a predetermined mount, (b) a step of forming a catalyst particle layer on the release layer after drying, c) After drying, the step of forming a coating layer on the catalyst particle layer is manufactured, and the mount is peeled off from the transfer paper and attached to the oxygen separation membrane. For the formation of each layer, a screen printing method is preferably used, but it can also be formed by a doctor blade method, an offset printing method, or the like.

  The release layer can be composed of an appropriate organic compound that can be easily dissolved in water or the like. For example, the release layer is formed by stretching a solution of dextrin in water on the mount and drying it. In this case, the concentration of the solution is, for example, 5 to 40 (wt%).

  The catalyst particle layer is preferably formed by applying and drying a paste in which the catalyst particles constituting the catalyst layer, a binder, a plasticizer, a dispersant, and a solvent are mixed on the release layer. . The paste preferably comprises 1 to 30 parts by weight of binder, 1 to 10 parts by weight of plasticizer, 0.01 to 5 parts by weight of dispersant, and 10 to 60 parts by weight of solvent with respect to 100 parts by weight of catalyst particles. Prepared by mixing in proportions. For mixing, a roller kneader is preferably used.

  The solvent may be selected from various solvents used for general transfer paper. For example, organic solvents such as toluene, alcohol and xylene, and aqueous solvents are preferably used.

  In addition, the binder can be appropriately selected from various materials used for general transfer paper according to the type of solvent, etc., but when the solvent is an organic solvent as described above, for example, Polyvinyl butyral, polyvinyl alcohol, polyethylene, methacrylic acid ester polymer, polyacrylic acid ester, resin binder, cellulose binder and the like are preferably used. In the case of an aqueous solvent, acrylic polymer, aqueous urethane, methylcellulose, polyvinyl alcohol, wax emulsion and the like are preferably used.

  In addition, the plasticizer can be appropriately selected from various materials used for general transfer paper depending on the type of the solvent, but when the solvent is an organic solvent as described above, For example, dibutyl phthalate, dimethyl phthalate, butyl stearate, phthalic acid ester, polyethylene glycol and the like are preferably used. In the case of an aqueous solvent, glycerin, dibutyl phthalate, polyalkyl glycol, triethylene glycol, polyol and the like are preferably used.

  Further, the dispersant can be appropriately selected from various materials used for general transfer paper according to the type of the solvent, etc., but when the solvent is an organic solvent as described above, For example, fatty acids and synthetic surfactants are preferably used. In the case of an aqueous solvent, phosphate, allyl sulfonic acid and the like are preferably used.

  The coating layer is preferably formed by applying a solution or paste obtained by dissolving a resin such as acrylic resin or methacrylic acid in a suitable organic solvent on the catalyst particle layer and drying it. The concentration of the resin is preferably about 5 to 40 (wt%).

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In the following embodiments, the drawings are appropriately simplified or modified, and the dimensional ratios, shapes, and the like of the respective parts are not necessarily drawn accurately.

  FIG. 1 is a perspective view showing an oxygen separation membrane element 10 according to an embodiment of the present invention, and FIG. 2 is an enlarged view showing a main part of the cross-sectional structure. 1 and 2, the oxygen separation membrane element 10 has a diameter of about 20 (mm) and has a thin disk shape as a whole, and an oxygen separation membrane 12 constituting an intermediate portion in the thickness direction. And an oxygen dissociation catalyst layer 18 and an oxygen recombination catalyst layer 20 provided on the front surface 14 and the back surface 16 respectively.

The oxygen separation membrane 12 is made of a lanthanum perovskite such as La _0.7 Sr _0.3 Ga _0.6 Fe _0.4 O ₃ or La _0.6 Sr _0.4 Ti _0.3 Fe _0.7 O _3, and has a thickness of about 0.5 (mm). The shape. This lanthanum perovskite is a mixed conductive ceramic having both oxygen ion conductivity and electronic conductivity. Therefore, while being dense, oxygen in contact with the front surface 14 or the back surface 16 can be ionized and transmitted, for example, from the front surface 14 toward the back surface 16.

The oxygen dissociation catalyst layer 18 is a porous layer made of, for example, La _0.6 Sr _0.4 CoO _3, and is formed on substantially the entire surface 14 with a uniform thickness dimension of, for example, about 100 (μm). . The dissociation catalyst layer 18 is provided to promote oxygen dissociation and ionization on the surface 14.

  The oxygen recombination catalyst layer 20 is a porous layer made of, for example, NiO, and is formed on substantially the entire back surface 16 with a uniform thickness of, for example, about 100 (μm). The recombination catalyst layer 24 is provided to promote recombination of oxygen ions on the back surface 16. The dissociation catalyst layer 18 and the recombination catalyst layer 20 are, for example, on the inner surface of the outer peripheral edge of the oxygen separation membrane 12 on the front surface 14 and the rear surface 16, for example, in the inner side of the annular region having a width of about 1 (mm). The oxygen separation membrane 12 is exposed in the annular region. The catalyst layers 18 and 20 are formed by arranging the catalyst particles 21 with high uniformity as schematically shown in FIG. Therefore, there are very few voids between the catalyst particles 21 in the catalyst layers 18 and 20 and they are relatively dense, and the supported amount is large relative to the thickness dimension, and the catalyst particles 21 are separated from the oxygen. The contact area with the surface of the film 12 is increased.

FIG. 4 is a process diagram for explaining the manufacturing method of the oxygen separation membrane element 10 described above. In FIG. 4, in the granulation step P1, for example, a commercially available La _0.7 Sr _0.3 Ga _0.6 Fe _0.4 O ₃ or La _0.6 Sr _0.4 Ti _0.3 Fe _0.7 O ₃ powder having an average particle diameter of about 1 (μm), water, a binder, Then, a slurry is prepared by mixing with a dispersant, and a raw material powder having an average particle diameter of about 60 (μm) is sprayed and granulated using, for example, a spray drier. Next, in the pressure forming step P2, the granulated raw material powder is press-molded at a pressure of about 100 (MPa), for example, and a circle having a diameter of about 25 (mm) and a thickness of about 3 (mm) is obtained. A plate-like molded body is obtained. The size of the molded body is a value determined in consideration of firing shrinkage and polishing allowance so as to obtain the oxygen separation membrane 12 having the above dimensions. Next, in the firing step P3, the molded body is held at a temperature of about 200 to 500 (° C.) for about 10 hours in the atmosphere for about 10 hours to decompose and remove organic substances, and further at a temperature of about 1500 (° C.) in the air. The molded body is fired by holding for about 3 hours. In the thickness polishing step P4, the dense sintered body obtained in this way is subjected to mechanical polishing using a surface grinder or the like, for example, a flat film having a thickness of about 0.5 (mm), that is, the aforementioned film An oxygen separation membrane 12 is obtained.

  On the other hand, in the paste preparation step PP1, a solution or paste for forming a release layer 28, a catalyst particle layer 26, and a coating layer 24 described later is prepared. The release layer solution is prepared, for example, by dissolving a commercially available dextrin in water to obtain a solution having a concentration of, for example, about 5 to 40 (wt%).

Also, the catalyst particle layer paste comprises 100 parts by weight catalyst particles, 1 to 30 parts by weight binder, 1 to 10 parts by weight plasticizer, 0.01 to 5 parts by weight dispersant, and 10 to 60 parts by weight solvent. For example, using a roller kneader or the like to prepare a paste. As the catalyst particle layer paste, a paste for forming the oxygen dissociation catalyst layer 18 and a paste for forming the oxygen recombination catalyst layer 20 are prepared. As the catalyst particles for constituting the oxygen dissociation catalyst layer 18, for example, La _0.6 Sr _0.4 CoO ₃ powder having an average particle diameter of about 2 (μm) is used, and the catalyst for constituting the oxygen recombination catalyst layer 20. As the particles, for example, NiO powder having an average particle diameter of about 7 (μm) is used. Any of these commercially available products can be used.

  Moreover, the said solvent can use organic solvents, such as toluene, alcohol, and xylene, water, etc., for example. When an organic solvent is used, for example, polyvinyl butyral, polyvinyl alcohol, polyethylene, methacrylic acid ester polymer, polyacrylic acid ester, resin-based binder, cellulose-based binder and the like are used as the binder, and as the plasticizer, for example, dibutyl Phthalate, dimethyl phthalate, butyl stearate, phthalate ester, polyethylene glycol and the like are used, and as the dispersant, for example, fatty acid, synthetic surfactant and the like are used.

  When water is used as a solvent, for example, an acrylic polymer, aqueous urethane, methyl cellulose, polyvinyl alcohol, wax emulsion or the like is used as a binder, and as a plasticizer, for example, glycerin, dibutyl phthalate, polyalkyl glycol, trialkyl. Ethylene glycol, polyol and the like are used, and as the dispersant, for example, phosphate, allyl sulfonic acid and the like are used.

  The coating layer paste (or solution) is prepared by, for example, dissolving an acrylic resin, methacrylic acid, or the like in an organic solvent at a concentration of, for example, 5 to 40 (wt%) to obtain a paste or solution.

  Next, in the application step PP2, the release layer solution, the catalyst particle layer paste, and the coating layer paste are sequentially applied onto a mount made of paper, PET film, or the like. Thereby, the transfer paper 22 (see FIG. 5 described later) for the oxygen dissociation catalyst layer 18 and the oxygen recombination catalyst layer 20 in which the release layer 28, the catalyst particle layer 26, and the coating layer 24 are laminated on the mount. Each is obtained. The release layer 28 is formed, for example, by applying a release layer solution on a mount and stretching and drying it. The catalyst particle layer 26 is formed by applying a catalyst particle layer paste on the release layer 28 by, for example, a screen printing machine and drying. The coating layer 24 is formed by applying a coating layer paste on the catalyst particle layer 26 by, for example, screen printing and drying. The thickness dimension of the catalyst particle layer 26 is determined in consideration of the respective firing shrinkage so that the thickness dimension of the catalyst layers 18 and 20 described above can be obtained. Further, the coating method is not limited to the above, and for example, a doctor blade method or an offset printing method may be used. In this embodiment, the paste preparation process PP1 and the coating process PP2 correspond to the transfer paper manufacturing process.

  Next, in the peeling step PP3, for example, water is dropped on the transfer paper 22 manufactured as described above to peel off the mount, and then in the catalyst layer transfer step P5, the mount is peeled off as shown in FIG. The transferred transfer paper 22, that is, the layered body is attached to the front surface 14 and the back surface 16 of the oxygen separation membrane 12. 5A shows the oxygen separation membrane 12, FIG. 5B shows the state in the middle of attaching the transfer paper 22 to the surface 14, and FIG. 5C shows the state in which the transfer paper 22 has been attached to the both surfaces 14 and 16. Is. In this pasting completed state, the transfer paper 22 has a coating layer 24, a catalyst particle layer 26, and a release layer 28 in this order from the oxygen separation membrane 12 side, as shown in the upper right side of the circled area surrounded by the alternate long and short dash line. It is pasted in the direction. The same applies to the back surface 16 (not shown). That is, the catalyst particle layer 26 is attached via the coating layer 24.

  Next, after drying at a temperature of, for example, about 100 (° C.) in the drying step P6, a baking treatment is performed in the baking step P7 by holding at a temperature of, for example, about 1000 (° C.) for about one hour. Thus, the oxygen separation membrane element 10 is obtained by baking the catalyst layers 18 and 20 on the front surface 14 and the back surface 16, respectively. The rate of temperature increase in the firing step is, for example, about 1 (° C./min). Since the catalyst layers 18 and 20 are thus provided by transfer, a structure in which the catalyst particles 21 are uniformly and densely arranged as described above can be obtained.

  The results of evaluating the oxygen permeation rate of the oxygen separation membrane element 10 manufactured as described above and configured as described above will be described below. The oxygen transmission rate was evaluated using the reactor 30 shown in FIG. In FIG. 6, a reactor 30 includes cylindrical tubes 32 and 34 made of ceramics such as alumina and open at both ends, arranged vertically with the oxygen separation membrane element 10 interposed therebetween, and on the inner peripheral side thereof, for example, Gas introduction pipes 36 and 38 made of ceramics such as alumina are inserted. In the oxygen separation membrane element 10, the surface 14 on which the oxygen dissociation catalyst layer 18 is provided is located on the upper side in FIG. 6, that is, on the cylindrical tube 32 side, and the back surface 16 on which the oxygen recombination catalyst layer 20 is provided is the cylindrical tube 34. It is arranged in the direction located on the side. In addition, heaters 40 and 40 are disposed on the outer peripheral side of the cylindrical tubes 32 and 34. The cylindrical tubes 32 and 34 and the oxygen separation membrane element 10 are hermetically sealed with sealing materials 42 and 42 such as glass. The gas introduction pipes 36 and 38 are arranged at a distance from the surface of the oxygen separation membrane element 10 by a distance necessary for gas supply.

  In such a reactor 30, while the inside of the apparatus is heated to a temperature of about 1000 (° C.) by the heaters 40, 40, air, that is, a gas containing oxygen is introduced into the cylindrical tube 32 from the gas introduction tube 36, and fuel A hydrocarbon such as pure methane gas is introduced from the side, that is, the gas introduction pipe 38. Both the air introduction amount and the methane gas introduction amount are, for example, about 10 to 200 (cc / min). Prior to the measurement, for example, while the inside of the cylindrical tube 34 is heated to a temperature of about 1000 (° C.) by the heaters 40, 40, for example, a mixed gas of hydrogen 10 (%) and argon 90 (%) is introduced into the gas introduction tube 38. To the inside of the cylindrical tube 34 and heated in a reducing atmosphere. Thereby, the recombination catalyst layer 24 provided on the lower surface 16, that is, the nickel oxide is partially or completely reduced, and the function as an oxygen recombination catalyst is exhibited.

  The air introduced from the gas introduction pipe 36 as described above is in contact with the surface of the oxygen separation membrane element 10, that is, the dissociation catalyst layer 18 and the surface 14 of the oxygen separation membrane 12, while the gas introduction pipe 36 and the cylindrical pipe 32 are in contact with each other. Exhaust is performed as shown by the arrow in FIG. 6 through an exhaust passage 44 formed therebetween. At this time, oxygen in the air is dissociated and ionized by the oxygen dissociation action and ionization action of the oxygen separation membrane 12 and the dissociation catalyst layer 18 provided on the surface 14 thereof, so that the oxygen ions have oxygen ion conductivity. 6 is transported from the front surface 14 side to the back surface 16 side through the oxygen separation membrane 12 having the structure shown in FIG.

  The oxygen ions that have reached the back surface 16 become oxygen molecules due to the recombination action of the oxygen separation membrane 12 and the recombination catalyst layer 20 provided on the back surface 16, and are extracted from the back surface 16. Thereby, oxygen permeate | transmits from the surface 14 side to the back surface 16 side. However, since the oxygen separation membrane 12 is dense as described above and other gases cannot be ionized, no gas other than oxygen is transmitted. That is, oxygen with extremely high purity is produced from air.

In addition, the oxygen that has permeated in this way is in the form of ions or recombined, and then on methane gas or the like introduced from the gas introduction pipe 38 and its back surface 16, in the recombination catalyst layer 20, or in the vicinity thereof. The reaction causes a partial oxidation reaction of methane as shown in the following formula (1). The generated synthesis gas of carbon monoxide and hydrogen is recovered from a recovery path 46 formed between the gas introduction pipe 38 and the cylindrical pipe 34. The recovered synthesis gas is used, for example, for liquid fuel synthesis. As is clear from the above description, in this embodiment, the front surface 14 corresponds to one surface and the back surface 16 corresponds to the other surface. Further, as is clear from the above description, when no methane gas is introduced from the gas introduction pipe 38, oxygen can be recovered from the recovery path 46, and the reactor 30 can be used as an oxygen production apparatus.
CH ₄ + 1 / 2O ₂ → CO + 2H ₂ (1)

  The above test was performed for about 3 hours, for example, and the evaluation results obtained by measuring the synthesis gas and the exhaust gas by gas chromatography were compared with the conventional method in which the catalyst layers 50 and 52 having the same composition as the catalyst layers 18 and 20 were provided by dip coating ( That is, it is shown in Table 1 below together with the evaluation results of the oxygen separation membrane element 54 (see FIG. 7) of Comparative Example. The oxygen separation membrane element 54 of the comparative example is prepared by mixing an organic solvent with the catalyst material to prepare a slurry, and immersing the oxygen separation membrane 12 to coat the slurry, and then, for example, at 100 (° C.) for about 3 hours. It was dried and further manufactured by baking at 1000 (° C.) for 1 hour. The oxygen transmission rate was calculated from the oxygen concentration and flow rate in the synthesis gas, and the oxygen transmission area of the oxygen separation membrane element 10. Further, this evaluation was performed by unifying the thicknesses of the catalyst layers 18, 20, 50, and 52 to 20 (μm) for the purpose of confirming the effect due to the difference in the manufacturing method. That is, the structure and manufacturing method of the examples and comparative examples are the same except that the method for forming the catalyst layer is different.

  As shown in Table 1 above, according to the oxygen separation membrane 10 of the example in which the catalyst layers 18 and 20 are provided by transfer, compared with the conventional oxygen separation membrane 54 in which the catalyst layers 50 and 52 are provided by dip coating. Thus, although the catalyst layer 18 and the like have the same thickness, an oxygen transmission rate of 1.7 times or more can be obtained. That is, by forming the catalyst layers 18 and 20 by transfer, it is possible to obtain higher characteristics than when formed by dip coating. In the catalyst layers 18 and 20 formed by the transfer, the catalyst particles 21 are uniformly and densely arranged as shown in FIG. 3, whereas the catalyst layers 50 and 52 formed by dip coating are shown in FIG. As shown, since the catalyst particles 21 are unevenly arranged and sparse, the amount of catalyst supported by the latter is reduced even if the thickness is the same, and the catalyst particles 21 and the surface of the oxygen separation membrane 12 are not. The contact area is small. Therefore, even if the catalyst thickness is the same, the promoting action of the oxygen separation membrane element 10 of the embodiment is increased, so that a high oxygen transmission rate can be obtained.

FIG. 8 shows the result of evaluating the relationship between the thickness dimension of the catalyst layers 18 and 20 and the oxygen permeation rate when the oxygen separation membrane 12 is made of La _0.6 Sr _0.4 Ti _0.3 Fe _0.7 O _3. This is shown together with a comparative example in which layers 50 and 52 are provided. In any film thickness, the thickness dimensions of the catalyst layers 18 and 20 were set to the same value. According to the examples, it is clear that the oxygen permeation rate tends to increase as the supported thickness of the catalyst layer increases. That is, the oxygen transmission rate is only about 5.3 (cc / min / cm ² ) at a supporting thickness of about 10 (μm), but the oxygen transmission rate rapidly increases as the supporting thickness increases up to about 20 (μm). It becomes high and becomes about 6.6 (cc / min / cm ² ). Although the change becomes loose when exceeding this, about 7.1 (cc / min / cm ² ) with a supporting thickness of about 50 (μm), about 7.9 (cc / min / cm ² ) with a supporting thickness of about 100 (μm), With a support thickness of about 200 (μm), the oxygen permeation rate increases as the film thickness increases, ie, about 8.3 (cc / min / cm ² ). As is apparent from FIG. 8, the oxygen transmission rate is substantially saturated at about 100 (μm). That is, it is understood that it is most preferable to set the supporting thickness to about 100 (μm). In the above evaluation, the transfer paper 22 provided with the catalyst particle layer 26 having the thickness to be formed was prepared, and each desired transfer thickness was obtained by one transfer. The carrying thickness can be increased by preparing and laminating transfer paper provided with the catalyst particle layer 26.

On the other hand, in the comparative example in which the catalyst layers 50 and 52 are provided by dip coating, the support thickness of about 10 (μm) is only about 3.4 (cc / min / cm ² ), and the support is about 20 (μm). Even the thickness remains at about 3.8 (cc / min / cm ² ). That is, although the tendency for the oxygen permeation rate to increase with the increase in the carrying thickness was recognized, it remained at a significantly lower value than in the examples. Moreover, when the carrying thickness was set to 30 (μm) or more, it was unusable due to peeling from the oxygen separation membrane 12 during firing. In addition, for the purpose of confirming the limit due to dip coating, the thickness of a single support was set to about 20 (μm), and evaluation was carried out to increase the support thickness by stacking, but the thickness was increased to 60 (μm) (ie 3 layers). However, the oxygen transmission rate was about 5 (cc / min / cm ² ). In addition, this is the limit of the carrying thickness, and if it is thicker than that, peeling occurred as in the case of a single layer.

  In short, according to the present embodiment, since the catalyst layers 18 and 20 are formed with a uniform film thickness by transfer, cracks and peeling are hardly caused even if the film thickness is increased. An oxygen separation membrane element 10 having a higher oxygen transmission rate is obtained. Moreover, the catalyst layers 18 and 20 formed by the transfer have the same film compared to the catalyst layers 50 and 52 formed by direct application of slurry or the like because the catalyst particles 21 are uniformly arranged and closely arranged. Even if the thickness is increased, the amount of support increases, so that there is an advantage that a high oxygen transmission rate can be obtained. Further, there is no inconvenience of increasing the number of supporting steps as in the CVD (chemical vapor deposition) method, etc., and a printing machine according to the shape and size of the oxygen separation membrane on which the catalyst layers 18 and 20 are to be formed as in direct printing. There is an advantage that it is not necessary to change the printing conditions such as the printing plate and paste preparation.

Further, according to the present embodiment, as shown in FIG. 6, when an O ₂ -containing gas is supplied from the gas introduction pipe 36 to the one surface side of the oxygen separation membrane element 10, oxygen therein is selectively ionized. Thus, the oxygen in the O ₂ -containing gas is efficiently separated because it is permeated through the oxygen separation membrane 12 and is recombined and recovered on the other side, that is, on the cylindrical tube 34 side. Can be manufactured. Further, by supplying the CH ₄ -containing gas from the gas introduction pipe 38 to the other surface side, oxygen and its CH ₄ are combined, and the generated synthesis gas (CO + 2H ₂ ) is recovered. Therefore, the oxygen permeation rate is high and oxygen can be efficiently permeated to the other surface side, so that there is an advantage that a highly efficient reactor 30 can be obtained.

  Next, another embodiment of the present invention will be described. In the following embodiments, portions common to the above-described embodiments are denoted by the same reference numerals and description thereof is omitted.

  The oxygen separation membrane element 56 shown in FIG. 9 has a tube shape in which one end is sealed. The oxygen separation membrane element 56 is configured by providing, for example, a recombination catalyst layer 62 on the outer peripheral surface 60 and a dissociation catalyst layer 66 on the inner peripheral surface 64 of a tubular oxygen separation membrane 58, respectively. As the constituent materials of these parts, for example, the same materials as those in the above-described embodiments can be used. A gas introduction pipe 68 is inserted on the inner peripheral side of the oxygen separation membrane 58. The gas introduction pipe 68 is configured in the same manner as the gas introduction pipes 36 and 38, for example.

  As shown in FIG. 9, the oxygen separation membrane element 56 is used by introducing an oxygen-containing gas from a gas introduction pipe 68 while supplying, for example, methane gas to the outer peripheral side thereof. As a result, a partial oxidation reaction of methane with oxygen that has passed through the oxygen separation membrane 58 occurs, and the synthesis gas can be recovered, as in the case of the reactor 30 described above. In FIG. 9, the methane gas supply path and the synthesis gas recovery path are conceptually omitted. Thus, the oxygen separation membrane element is not limited to a flat plate shape such as a disc shape, and can take an appropriate shape such as a tube shape.

  FIG. 10 is a diagram for explaining a process of forming the recombination catalyst layer 62 in the manufacturing process of the oxygen separation membrane element 56 described above. Since the outer circumferential surface 60 of the oxygen separation membrane 58 of the oxygen separation membrane element 56 has a cylindrical shape, it is difficult to obtain a uniform carrying thickness by directly printing the paste on the outer circumferential surface 60 or by dip coating. . However, according to the present embodiment, after the transfer paper 70 is manufactured by applying a solution or paste to the mount in a flat state to form a catalyst particle layer or the like, the transfer paper 70 is made of oxygen as shown in FIG. The recombination catalyst layer 62 can be easily provided by being wound around the separation membrane 58. That is, since the transfer paper 70 has high flexibility, the catalyst layer can be easily formed on such a curved surface as well as a flat surface. The oxygen separation membrane sealing end was provided with a recombination catalyst layer 62 by pasting a transfer paper 70 cut into an appropriate shape, for example, a 3/4 circular shape, so that a hemispherical surface was obtained at the time of pasting. Further, the dissociation catalyst layer 66 on the inner peripheral surface 64 may be provided, for example, by dip coating similar to the conventional one.

  FIG. 11 is a plan view showing the entire oxygen separation membrane element 72 of still another embodiment, and FIG. 12 is an enlarged view of a part of the dissociation catalyst layer 74 provided on the surface 14 of the oxygen separation membrane 12. FIG. 13 is an enlarged view showing the main part of the cross section of the oxygen separation membrane element 72. In addition, the back surface 16 of the oxygen separation membrane element 72, that is, the recombination catalyst layer 76 also has the same shape as that shown in FIGS. 11 to 13, the dissociation catalyst layer 74 and the recombination catalyst layer 76 provided on the front surface 14 and the back surface 16 of the oxygen separation membrane 12 have a large number of grooves 78 extending along two directions orthogonal to each other. Is provided. The groove 78 has a rectangular cross section as shown in FIG. 12 and FIG. 13, and each of the grooves 78 extending along any direction has a width dimension W of about 50 (μm), for example, and 100 (μm). It has a depth dimension D of about, and is provided with a uniform mutual interval P of about 100 (μm), for example. For this reason, in the catalyst layers 74 and 76, a large number of protrusions having a square shape with, for example, a side of about 100 (μm) and a height dimension of about D = 100 (μm) between the grooves 78. 80 are provided along two directions orthogonal to each other, for example, with a mutual interval of about W = 50 (μm), that is, with a central interval of about 150 (μm), and their surfaces are formed by these grooves 78 and projections 80. It has a rough surface.

  When the catalyst layers 74 and 76 are provided by transfer as described above, the grooves 78 and the projections 80 are provided by applying a catalyst particle layer paste on the mount in a planar shape having the grooves 78 and the projections 80. It is what was done. According to this embodiment, since the catalyst layers 74 and 76 are provided by transfer, such patterning can be easily formed by appropriately setting the opening pattern of the screen printing plate making.

According to the present embodiment, regular irregularities arranged in a lattice pattern, that is, orthogonal to each other, are formed on the front and back surfaces of the oxygen separation membrane element 72.
The gas that has reached the vicinity of the surface flows along the groove 78 (that is, is rectified) as shown by the arrow in FIG. 12, and consists of the bottom surface of the groove 78, the side surface of the protrusion 80, and the top surface thereof. The oxygen separation membrane 12 is brought into contact with a wide area. Therefore, on the dissociation catalyst layer 74 side, the surface area is increased and turbulence is prevented, so that the contact opportunity between oxygen and the oxygen separation membrane 12 is dramatically increased. The reactivity with 12 is remarkably enhanced, and the ionization rate of oxygen is remarkably enhanced. In addition, on the recombination catalyst layer 76 side, the area where oxygen is recombined is significantly increased by increasing the surface area, so that the recombination rate of oxygen ions is significantly increased. Therefore, since the reaction rate is increased in any case, the oxygen transmission rate is further increased.

An oxygen separation membrane element 82 shown in FIG. 14 has an oxygen separation membrane 86 and the like provided on a porous support 84. In FIG. 14, the porous support 84 is made of perovskite such as La _0.7 Sr _0.3 Ga _0.6 Fe _0.4 O ₃ or La _0.6 Sr _0.4 Ti _0.3 Fe _0.7 O _{3, and has} a thickness of about 3 (mm), for example. It is a disk with a thickness of about 20 (mm) in diameter. The oxygen separation membrane 86 is made of, for example, a perovskite material having the same composition as the porous support 84, but is densely configured.

  For example, the recombination catalyst layer 90 is formed on the back surface 88 of the porous support 84 with a uniform thickness of about 100 (μm). The oxygen separation membrane 86 is provided on the surface 92 of the porous support 84 with a thickness of about 300 (μm), for example. The oxygen separation membrane 86 is provided, for example, in a state where a part thereof is permeated into the porous support 84. A dissociation catalyst layer 96 is provided on the surface 94 of the oxygen separation membrane 86. The recombination catalyst layer 90 and the dissociation catalyst layer 96 are configured in the same manner as the catalyst layers 18 and 20, for example, both are provided by a transfer method.

  According to such an oxygen separation membrane element 82, the overall mechanical strength is ensured by the porous support 84, so that it is easy to further increase the oxygen permeation rate by making the oxygen separation membrane 86 thinner. .

  In addition, said porous support body 84 is manufactured by the following manufacturing processes, for example. First, the porous material powder is mixed and kneaded with a binder, a dispersant and the like, and then dried at a temperature of about 100 (° C.) for about 24 hours to produce an aggregate. As the porous material powder, for example, a commercially available perovskite raw material having the above composition can be used. Next, this is crushed by a ball mill or the like, and is subjected to pressure molding at a pressure of about 100 (MPa), for example, to form a disk having a diameter of about 20 (mm) and a thickness of about 3 (mm). Next, the molded body is heated at a predetermined firing temperature, for example, about 1500 (° C.) for about 3 hours. Thereby, the porous support body 84 is obtained.

  After producing the porous support 84 in this manner, the constituent material powder of the oxygen separation membrane 86 is mixed with a solvent, a binder, and a dispersant using a ball mill or the like to prepare a slurry. The surface 92 side of the porous support 84 is immersed (dip) inside. Thereby, the surface layer portion on the surface 92 side of the porous support 84 is substantially uniformly impregnated with the slurry. Next, in the drying process, for example, drying is performed at a temperature of about 60 (° C.) for about 4 hours, and in the baking process, for example, heating in the atmosphere at a temperature of about 1500 (° C.) for about 3 hours to separate oxygen. A membrane 86 is formed on the porous support 84. The dipping process and the drying process are repeated an appropriate number of times so as to obtain a desired film thickness of, for example, about 0.3 (mm). The film thickness of the oxygen separation membrane 86 can also be adjusted by adjusting the slurry viscosity, the immersion time, and the like. Since the oxygen separation membrane 86 is provided in this manner, the oxygen separation membrane 86 is provided in a state where a part of the oxygen separation membrane 86 permeates the surface 92 of the porous support 84. The recombination catalyst layer 90 can also be provided on the back surface 88 by dip coating similar to the oxygen separation membrane 86.

Table 2, FIG. 15, and FIG. 16 below show the results of measuring the oxygen permeation rate and the like of the oxygen separation membrane element 82 by changing the configuration of the porous support 84 in various ways. In this evaluation, the thickness dimension of the oxygen separation membrane 86 was set to 0.2 (mm). Further, in Table 2 below, Example A is one in which the porous support 84 and the oxygen separation membrane 62 are composed of La _0.7 Sr _0.3 Ga _0.6 Fe _0.4 O ₃ (LSGF), and Example B is La It is composed of _0.6 Sr _0.4 Ti _0.3 Fe _0.7 O ₃ (LSTF). The pore diameter, porosity, and bending strength are all characteristic values of the porous support 84. The pore diameter and porosity were measured by mercury porosimetry or BET method (for example, nitrogen adsorption method). Further, the oxygen permeation rate was performed using the reactor shown in FIG. 6 in the same manner as the oxygen separation membrane element 10 described above. The bending strength is a three-point bending strength, which is a value measured according to JIS R1601.

  As shown in Table 2 and FIGS. 15 and 16, the oxygen transmission rate tends to increase as the pore diameter and porosity of the porous support 84 increase. However, since the bending strength of the porous support 84 tends to be reduced accordingly, it is necessary to determine the pore diameter and the porosity of the porous support 84 in consideration of these balances. That is, in order to obtain a sufficiently high oxygen transmission rate, it is preferable that the pore diameter is larger than 0.1 (μm) and the porosity is larger than 5 (%). In order to maintain the bending strength of the porous support 84 sufficiently high to ensure the strength of the oxygen separation membrane element 82 as a whole, and to reduce the thickness of the oxygen separation membrane 86 sufficiently, the pore diameter should be reduced. It is desirable that the porosity is smaller than 20 (μm) and the porosity is smaller than 60 (%). Therefore, due to the balance between the two, in the embodiment including the porous support 84, the average pore diameter is in the range of 0.1 to 20 (μm) (not including the upper and lower limits), and the porosity is 5 to 60 (%). It is desirable to be within the range (not including the upper and lower limits).

  As mentioned above, although this invention was demonstrated in detail with reference to drawings, this invention can be implemented also in another aspect, A various change can be added in the range which does not deviate from the main point.

It is a perspective view which shows the whole disk-shaped oxygen separation membrane element of one Example of this invention. It is a figure which shows the cross-section of the oxygen separation membrane element of FIG. It is a figure which expands and further shows FIG. 2 typically. It is process drawing for demonstrating the manufacturing method of the oxygen separation membrane element of FIG. (a)-(c) is a figure explaining the implementation state of the transcription | transfer process of FIG. It is a figure explaining the structure of the reactor using the oxygen separation membrane element of FIG. It is a figure which shows typically the cross-section of the conventional oxygen separation membrane element which provided the catalyst layer by the dip coating. It is a figure explaining the relationship between the catalyst layer thickness of the oxygen separation membrane element of FIG. 1, and oxygen transmission rate. It is a figure which shows typically the cross-sectional structure of the oxygen separation membrane element of the other Example of this invention. It is a figure explaining the formation process of the catalyst layer at the time of manufacturing the oxygen separation membrane element of FIG. It is a top view which shows the whole oxygen separation membrane element of other Example of this invention. It is a figure which expands and shows a part of surface of the oxygen separation membrane element of FIG. It is a figure explaining the principal part of the cross-section of the oxygen separation membrane element of FIG. It is a side view which shows the whole oxygen separation membrane element of other Example of this invention. It is a figure which shows the relationship between the average pore diameter of the porous support body which comprises the oxygen separation membrane element of FIG. 14, an oxygen permeation | transmission speed | rate, and a three-point bending strength. It is a figure which shows the relationship between the porosity of the porous support body which comprises the oxygen separation membrane element of FIG. 14, oxygen permeation | transmission speed | rate, and three-point bending strength.

Explanation of symbols

10: oxygen separation membrane element, 12: oxygen separation membrane, 14: front surface, 16: back surface, 18: oxygen dissociation catalyst layer, 20: oxygen recombination catalyst layer

Claims (15)

In addition to a dense oxygen separation membrane having oxygen ion conductivity, a catalyst layer is provided on at least one of the oxygen dissociation side and the oxygen recombination side, and is dissociated from the gas and ionized on the one side. A method of manufacturing an oxygen separation membrane element for selectively permeating oxygen from one surface to the other surface and separating it from the gas by recombining oxygen ions on the other surface side,
A method for producing an oxygen separation membrane element, wherein the catalyst layer is formed by transferring a catalyst particle layer provided on a predetermined mount to the oxygen separation membrane. In addition to a dense oxygen separation membrane having oxygen ion conductivity, a catalyst layer is provided on at least one of the oxygen dissociation side and the oxygen recombination side, and is dissociated from the gas and ionized on the one side. An oxygen separation membrane element for selectively permeating oxygen from one surface to the other surface and separating it from the gas by recombining oxygen ions on the other surface side,
An oxygen separation membrane element, wherein the catalyst layer is formed by transfer. 3. The oxygen separation membrane element according to claim 2, wherein the catalyst layer has a plurality of protrusions arranged on the surface thereof at a constant center interval along one direction. The oxygen separation membrane element according to claim 2, wherein the oxygen separation membrane is a mixed conductor having oxygen ion conductivity and electron conductivity. The oxygen separation membrane has a general formula Ln _1-x Ae _x MO ₃ (where Ln is a lanthanoid, Ae is one or a combination of two or more selected from Ba, Sr, and Ca, M is Fe, Mn, Ga, Ti, Co, Zr, Ce, Mg, Ge, Zn, Cu, Sc, V, Cr, Ni, Y, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, Sb, Pb, Bi, One or a combination of two or more selected from Po, Al, In, and Sn, selected from complex compounds represented by 0 ≦ x ≦ 1), ZrO ₂ oxides, and CeO ₂ oxides 3. The oxygen separation membrane element according to claim 2, comprising one or a combination of two or more. The oxygen separation membrane is Ce _2-x Zr _x O _4-σ (where 0 <x <2, 0 ≦ σ ≦ 4), CeGd oxide, CeSm oxide, Ba (CaNb) ₂ oxide, BiVCu oxide 3. The oxygen separation membrane element according to claim 2, wherein the oxygen separation membrane element is composed of one or a combination of two or more selected from the group consisting of ZrO ₂ -based oxides. The oxygen separation membrane is made of a material containing one or a combination of two or more selected from magnesium oxide (MgO), aluminum oxide (Al ₂ O ₃ ), and yttrium oxide (Y ₂ O ₃ ). The oxygen separation membrane element according to claim 5 or 6. The oxygen separation membrane element according to any one of claims 5 to 7, wherein the oxygen separation membrane is made of a material containing a metal or metal oxide having electron conductivity. The oxygen separation membrane element according to claim 2, wherein the oxygen separation membrane is provided on the porous support so as to cover the entire surface thereof. The porous support has the general formula Ln _1-x Ae _x MO ₃ (where Ln is a lanthanoid, Ae is one or a combination of two or more selected from Ba, Sr, and Ca, and M is Fe, Mn) , Ga, Ti, Co, Zr, Ce, Mg, Ge, Zn, Cu, Sc, V, Cr, Ni, Y, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, Sb, Pb, Bi , Po, Al, In, Sn selected from one or a combination of two or more, a composite compound represented by 0 ≦ x ≦ 1), a ZrO ₂ oxide, a CeO ₂ oxide, magnesium oxide ( 10. The oxygen separation according to claim 9, comprising one or a combination of two or more selected from MgO), aluminum oxide (Al ₂ O ₃ ), silicon nitride (Si ₃ N ₄ ), and silicon carbide (SiC). Membrane element. The oxygen separation membrane element according to claim 9, wherein the oxygen separation membrane and the porous support are made of the same material. The oxygen separation membrane element according to claim 9, wherein the oxygen separation membrane and the porous support are made of materials having different compositions. 10. The oxygen separation membrane element according to claim 9, wherein the porous support has an average pore diameter r in a range of 0.1 <r <20 (μm) and a porosity p in a range of 5 <p <60 (%). Using the oxygen separation membrane element according to any one of claims 2 to 13, a raw material gas containing oxygen is supplied to one surface side, and oxygen separated from the raw material gas is recovered from the other surface side. An oxygen production method. The oxygen separation membrane element according to any one of claims 2 to 13,
A first gas supply path for supplying a gas containing oxygen to one surface side of the oxygen separation membrane element;
A second gas supply path for supplying a gas containing a predetermined compound to the other surface side;
And a gas recovery path for recovering a gas generated by a reaction between oxygen and the predetermined compound on the other surface side.

Images