JP2008246451A - Oxygen separation membrane element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an oxygen separation membrane element having higher oxygen permeation performance.
SOLUTION: A porous support 12 having a straight tubular hole with high gas diffusion performance is used, and a gap between the porous support 12 and a gas supply pipe 22 is sufficiently smaller than the straight tubular hole. The air supplied from the supply pipe 22 is preferably directed toward the intermediate layer 16, and a high oxygen transmission rate can be obtained.
[Selection] Figure 4

Description

  The present invention relates to an oxygen separation membrane element used for oxygen separation.

  For example, a dense electrolyte layer made of a ceramic material having oxygen ion conductivity is formed by dissociating oxygen from a gas on one side and recombining ionized oxygen ions on the other side, so that oxygen is released from one side. It is used for an oxygen separation membrane element that selectively permeates the surface and continuously separates oxygen from the gas. In particular, when the ceramic material is a mixed conductor having electron conductivity in addition to oxygen ion conductivity, electrons move in the direction opposite to the movement direction of oxygen ions in the electrolyte layer. There is an advantage that it is not necessary to provide an external electrode, an external circuit, or the like for electrically connecting the recombination surface and returning electrons from the recombination surface to the dissociation surface. According to the oxygen separation membrane element having such an electrolyte layer, oxygen can be easily separated from a gas containing oxygen. For example, oxygen can be used instead of a cryogenic separation method, a PSA (pressure fluctuation adsorption) method, or the like. It can be used as a manufacturing method.

The oxygen ion conductor as described above can also be used in an oxidation reaction apparatus such as a hydrocarbon partial oxidation reaction. For example, this oxygen ion conductor is formed into a film, oxygen-containing gas such as air is supplied to one surface thereof, and hydrocarbon such as methane (CH ₄ ) is supplied to the other surface, that is, the oxygen recombination side surface. If the gas containing it is supplied, the hydrocarbon can be oxidized by the permeated oxygen ions. Therefore, it can be used for GTL (Gas to Liquid: technology for synthesizing liquid fuel from natural gas by chemical reaction), production of hydrogen gas for fuel cells, and the like.

  In this type of oxygen separation membrane, the thinner the electrolyte membrane, the higher the oxygen transmission rate and the higher the separation performance. Therefore, instead of a self-supporting membrane used alone, the electrolyte membrane is formed of a thin film, and the membrane is formed on a porous support having a large number of pores penetrating in the thickness direction. Complementing the strength (that is, forming an asymmetric membrane) is performed (see, for example, Patent Documents 1 to 5). In addition, since it is desired that the oxygen permeation rate of the electrolyte membrane material itself is as high as possible, these Patent Documents 1 to 5 propose electrolyte membranes of various materials.

  Further, the oxygen separation membrane is considered to be preferably cylindrical, for example, cylindrical, considering use on a practical scale such as a gas separation membrane for a chemical plant (see, for example, Patent Document 5). The cylindrical element is relatively easy to seal and increase in size as compared with a flat plate structure. In addition, since a plurality of devices can be bundled closely together, it is advantageous in that the device can be miniaturized.

Due to the above circumstances, a cylindrical porous support is used, but in the asymmetric membrane structure, the gas diffusion performance of the porous support immediately affects the performance of the apparatus. Therefore, in order to produce an oxygen separation membrane with high separation performance, a support having high gas diffusibility is required. Further, in order to obtain a highly durable oxygen separation membrane, a support having high mechanical strength and high affinity for the electrolyte thin film is required.
Japanese Patent No. 2813596 JP 2003-225567 A Japanese Patent Laid-Open No. 2003-190792 JP 2003-210952 A JP 2002-292234 A

  Incidentally, in recent years, with the improvement of the performance of solid electrolyte membranes and catalysts, the gas diffusion performance of porous supports has come to regulate the performance of oxygen separation membranes. Therefore, further improvement of the gas diffusion performance of the porous support is required. In order to improve the gas diffusion performance, it is conceivable to further increase the pore diameter and porosity of the porous support. However, the mechanical strength of the porous support decreases as the pore diameter and porosity increase. For example, when the porosity is increased to about 90 (%), the material strength is decreased to about 10 (MPa), and the handleability and durability become insufficient. Moreover, since the conventional porous support is formed with communication holes in the gaps between the raw material particles, the communication holes are significantly bent. Therefore, even if the porosity and the pore diameter are increased, it is difficult to sufficiently improve the gas diffusion performance.

  In addition, when a porous support having high gas diffusion performance was prepared, an electrolyte membrane was formed and evaluated with a test apparatus, the higher the gas diffusion performance of the porous support, the more the porous support and the electrolyte membrane. It became clear that it was difficult to obtain the expected characteristics because the deviation from the oxygen permeation amount predicted from the performance increased.

  The present invention has been made against the background of the above circumstances, and an object thereof is to provide an oxygen separation membrane element having higher oxygen permeation performance.

  In order to achieve such an object, the gist of the oxygen separation membrane element of the present invention is a dense electrolyte layer having a cylindrical shape and a plurality of gases for supplying air to the inner peripheral surface of the electrolyte layer. A bottomed cylindrical support having a flow path and supporting the electrolyte layer from the inner peripheral side, and a gas supply inserted from the open end to the inner peripheral side to supply gas to the bottom of the support An oxygen separation membrane element including a pipe, wherein (a) a radial distance between an inner peripheral surface of the support and an outer peripheral surface of the gas supply pipe is smaller than a size of the gas flow path. is there.

  When using a cylindrical oxygen separation membrane element, configure it as a bottomed cylinder, insert a gas supply pipe from the open end to the inner periphery, and introduce gas containing oxygen from the bottom of the support Will do. According to the present invention, the distance between the inner peripheral surface of the support and the outer peripheral surface of the gas supply pipe in the radial direction, that is, the gap formed therebetween, supplies air from the support to the inner peripheral surface of the electrolyte layer. Therefore, the gas supplied from the front end of the gas supply pipe to the bottom of the porous support easily flows into the gas flow path. Therefore, since the gas containing oxygen is suitably supplied to the inner peripheral surface of the electrolyte layer, this is effectively used even when the gas diffusion performance of the porous support is enhanced, and oxygen having high oxygen permeability is obtained. A separation membrane element is obtained.

  Incidentally, in the conventional oxygen separation membrane element, the outer diameter of the gas supply pipe is significantly smaller than the inner diameter of the porous support, and a large space is formed between them. Conventionally, since the gas diffusion performance of the porous support was relatively low, most of the gas supplied from the gas supply pipe was discharged from the open end of the support without being used. is there. Even if the gas diffusion performance of the porous support is enhanced, no consideration has been given to the arrangement of the gas supply pipe, so that the gas supply from the gas flow path of the porous support is the same as before. The gap with the tube was large. Therefore, most of the gas is discharged as it is, and the gas flow rate flowing into the gas flow path toward the electrolyte layer is difficult to increase. Due to such circumstances, as described above, even though the gas diffusion performance of the porous support and the oxygen permeation rate of the electrolyte material were increased, the oxygen permeation performance as predicted from their characteristic values could not be obtained. it is conceivable that.

  In addition, the mutual space | interval of a support body outer peripheral surface and a gas supply pipe outer peripheral surface should just be made smaller than the magnitude | size of the said gas flow path, and there is no lower limit in particular. For example, even if they are in contact with each other, if there is no possibility of damage during reaction, firing or use, the distance between them may be zero, that is, a close state.

Further, as described above, the present invention can enjoy particularly high effects when the porous substrate has a high gas diffusion performance. Is equally applicable. However, it is particularly preferable to apply when the oxygen transmission rate is 10 (cc / min / cm ² ) or more.

  Here, preferably, a porous intermediate layer is provided between the porous support and the electrolyte layer. That is, in this embodiment, the electrolyte layer is supported by the porous support via the intermediate layer. The porous support of the present invention is desired to have as high a gas diffusion performance as possible. However, the higher the gas diffusion performance, the higher the porosity and it becomes difficult to form a dense thin film on the surface. Therefore, when a porous support having high gas diffusion performance is used, it is preferable to form a porous intermediate layer on the outer peripheral surface and provide an electrolyte layer thereon.

  The constituent material of the intermediate layer is not particularly limited. However, since it is for forming and supporting a thin electrolyte layer on the surface, the intermediate layer is preferably made of the same or similar material as the electrolyte layer.

  Moreover, what was manufactured with the appropriate manufacturing method can be used for said intermediate | middle layer according to the surface shape of a porous support body. For example, it can be formed by winding a sheet-like molded body obtained by extrusion molding or casting molding around a porous support and performing a baking treatment.

  Preferably, the plurality of gas flow paths are straight tubular holes provided in the peripheral wall of the cylindrical support so as to linearly penetrate from the inner peripheral surface to the outer peripheral surface, and the mutual intervals are the same. It is smaller than the maximum value of the passing dimension perpendicular to the gas flow direction of the straight tubular hole. In this way, since the straight tubular hole that linearly penetrates the peripheral wall of the porous support in the thickness direction has a significantly lower airflow resistance than the bent communication hole, the gas diffusion performance of the porous support is remarkably high. Enhanced. At this time, the straight tubular hole opens toward the gap between the gas supply pipe and the porous support, and the gas introduced from the tip of the gas supply pipe passes through the gap. If it is larger than that, the introduced gas is preferably introduced into the straight tubular hole in the process toward the open end of the porous support. The present invention is suitably applied when a porous support having such straight tubular holes is used.

  In said aspect, the form of a straight tubular hole and the manufacturing method of a porous support body are not specifically limited, The porous support body which has a straight tubular hole of a various shape by various methods can be manufactured. For example, after producing a cylindrical molded body by an appropriate method such as extrusion, a necessary number of through-holes are formed by machining on the outer peripheral surface before firing, and a firing process is performed. In this aspect, the shape, size, number, and the like of the straight tubular holes can be arbitrarily determined, but there is a problem that the manufacturing cost increases and the manufacturing cost increases as the number of straight tubular holes increases.

  In addition, for example, a plurality of perforated plates having through holes penetrating in the thickness direction on the inner peripheral portion thereof are prepared, and spacers that are separately manufactured or integrally formed with the perforated plates are provided on the annular end surface in the circumferential direction. A porous support may be formed by arranging a plurality of the perforated plates through the spacers and integrating them by heat treatment. In this case, a plurality of perforated plates are connected in the thickness direction via spacers to form a cylindrical shape as a whole, and the through hole portion functions as a hole on the inner peripheral side of the cylindrical support body. A gap formed between the board and the spacer functions as a straight tubular hole. The spacer can have an appropriate shape such as a columnar shape, a prismatic shape, etc., and the height dimension, the mutual interval in the circumferential direction of the annular end surface, the number of spacers provided between the one end surfaces, etc. It can be appropriately determined according to the desired gas diffusion performance, mechanical strength, and difficulty in forming a film on the outer peripheral surface. For example, the height of the spacer, that is, the distance between the perforated plates is preferably 0.01 to 50 (mm), preferably 5 (mm) or less, and the gas diffusion resistance is ensured while ensuring the mechanical strength. It can be made sufficiently small.

  Further, in the aspect in which a plurality of perforated plates are laminated and integrated as described above, the gas supply pipe is made of a heat-resistant material such as a refractory material or a heat-resistant metal, and a support (that is, a perforated plate) When the reactivity with the constituent material is sufficiently low, the gas supply pipe may be pierced into the through hole of the laminated perforated plate and subjected to a firing treatment. In this way, since the gas supply pipe functions also as an alignment jig for the laminated perforated plates, warping and bending in the firing process of the porous support are suitably suppressed. It is also possible to carry out the firing by supporting the gas supply pipe in a state of being pierced through the gas supply pipe. In the present application, “hanging firing” means that the perforated plate is suspended by the gas supply pipe regardless of the orientation, such as the direction in which the longitudinal direction of the gas supply pipe matches the vertical direction or the direction in which the gas supply pipe matches the horizontal direction. Includes various supported embodiments.

  Preferably, the support body is provided with a cylindrical base portion extending along one direction and an outer peripheral surface of the base portion so as to project away from each other in the circumferential direction and along the longitudinal direction of the base portion. The plurality of gas flow paths are formed between the plurality of rib-shaped portions, and the mutual interval is smaller than the height dimension of the rib-shaped portions. is there. In this way, since the gas flow path formed between the rib-like portions of the porous support extends straight from the bottom side of the support toward the open end, the airflow resistance is extremely small. If the mutual interval with the gas supply pipe is smaller than the height, the gas supplied from the tip of the gas supply pipe to the bottom of the support is suitably introduced into the gas flow path. In this aspect, the electrolyte layer is provided directly on the rib-like portion or via a porous support layer. In any case, the gas introduced into the gas flow path is preferably used. It is directed to the inner peripheral surface of the electrolyte layer.

  In the above aspect, the support layer provided on the outer peripheral surface of the support (i.e., the cylindrical surface connecting the radial front end surfaces of the rib-shaped portions) may be integrated by firing by winding a separately molded one. May be molded. In this embodiment, the cross section perpendicular to the longitudinal direction of the support has a uniform shape both when the support layer is provided integrally and when it is not provided. can do.

Preferably, the support has the general formula Ln _1-x Ae _x MO ₃ (where Ln is at least one selected from lanthanoids, Ae is at least one selected from Sr, Ca, Ba, and M is Mg). , Mn, Ga, Ti, Co, Ni, Al, Fe, Cu, In, Sn, Zr, V, Cr, Zn, Ge, Sc, Y, represented by 0 ≦ x ≦ 1) The gas supply pipe has at least an outer peripheral surface made of magnesium oxide (MgO). In this way, even when the support is composed of a highly reactive lanthanide-based perovskite complex oxide, the gas supply pipe is composed of magnesium oxide having a low reactivity with the perovskite complex oxide. When the gap between the support and the gas supply pipe is extremely small, it is preferable to prevent the characteristics of the support from changing as a result of reaction during the manufacturing process or use even if they partially contact each other. Is done.

  Preferably, in the above aspect, the gas supply pipe is made of electrofused magnesia having a purity of 95 (%) or higher or light-burned magnesia having a purity of 97 (%) or higher. This further suppresses the reaction with the support made of the perovskite complex oxide.

Electrofused magnesia reacts with magnesium chloride and alkali to produce magnesium hydroxide, dehydrated and dried, then calcined at a temperature of about 1400 (° C) and called heavy calcined magnesia or clinker Magnesium oxide is produced, melted (electrofused) at a temperature of about 3000 (° C.), cooled, and pulverized. The purity of electrofused magnesia is generally increased by removing impurities during electromelting. Since it is manufactured in this manner, the fused magnesia is crystal-grown, has high crystallinity, and becomes a powder having a relatively large particle size. The particle shape depends on the pulverized state, but since the molten product is pulverized, the particle shape is often burnt or angular. It has high heat resistance and is also used for heat-resistant bricks. Compared with light-fired magnesia, it is inactive. When sintering to produce heat-resistant bricks and the like, a large amount of a sintering aid such as SiO ₂ , Al ₂ O ₃ , CaO is usually added.

  Light calcined magnesia is obtained by calcining dehydrated and dried magnesium hydroxide at a temperature in the range of 1000 to 1200 (° C.) and pulverizing it. The purity of light-burned magnesia is generally increased by washing the powder obtained. Since it is manufactured in this way, the crystallinity is lower than that of electrofused magnesia, and since it can be easily pulverized, it is easy to obtain a fine powder. The particle shape is a relatively uniform spherical shape. Further, since the particle size is fine and the specific surface area is large, the activity is high and the reactivity is high. Therefore, there are many chemical uses such as various ceramic raw materials, rubber and plastic compounding agents.

  Preferably, the oxygen separation membrane element is fired by applying a slurry or the like for forming the electrolyte layer to the outer peripheral surface of the porous support, and then hanging and supporting it with the gas supply pipe. It is a thing. In this way, since the firing process can be performed in a state where the film forming part of the electrolyte layer does not contact the setter for firing and the like, the reaction between the electrolyte layer and the setter for firing is suitably suppressed.

The constituent material of the electrolyte layer is not particularly limited, and the present invention is applied to an oxygen separation membrane element including an electrolyte layer made of various materials. However, in order to obtain high oxygen permeation performance, the one made of Ln-based perovskite complex oxide is most preferable. For example, LaSrTiFeO ₃ , LaSrGaFeO ₃ , LaSrMnFeO _{3 and the} like can be mentioned. These have the advantage of high ion conductivity and electronic conductivity.

The constituent material of the porous support is not particularly limited as long as it does not react with the electrolyte layer and change its characteristics. However, in order to suppress damage due to the difference in thermal expansion amount even when heated or cooled during the manufacturing process or use, the same or similar material as the electrolyte layer is preferable, magnesia, zirconia, alumina Ceria and the like are also preferable. For example, when the porous support is made of an Ln-based perovskite composite oxide, the thermal expansion coefficient is about 12 to 13 × 10 ⁻⁷ (/ ° C.), and thus the thermal expansion coefficient is 13 × 10 ⁻⁷ (/ Magnesia of about ° C.) and ceria of about 12 × 10 ⁻⁷ (/ ° C.) are most preferable, but when the intermediate layer is provided between the porous support and the electrolyte layer, the intermediate layer is thermally expanded. Since it has an effect of relaxing the difference in coefficient, there is no particular problem even with zirconia having a thermal expansion coefficient of about 10 to 11 × 10 ⁻⁷ (/ ° C.) or alumina having a coefficient of about 6 to 7 × 10 ⁻⁷ (/ ° C.).

  The constituent material of the gas supply pipe is not particularly limited. However, when the gas supply pipe is disposed in contact with the porous support, it is preferably made of a material that does not react and change its quality. For example, when the porous support is composed of an Ln-based perovskite complex oxide, it is preferably composed of magnesia. Further, when the porous support is composed of the other materials described above, the same materials as those are preferable, but other materials may be used.

  The gas supply pipe is preferably dense. If it does in this way, the gas which is going to supply will be suitably supplied toward the bottom part of a support body, without leaking on the way.

  Preferably, the gas supply pipe has a groove extending along the axial direction on the outer peripheral surface. In this way, even when the gap between the porous support and the gas supply pipe is sufficiently reduced and the air flow rate supplied from the gas supply pipe is increased, air can easily flow through the groove. Pressure loss is reduced. Such grooves may be provided in an appropriate size or number according to the size of the gap or the air flow rate.

  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 entire oxygen separation membrane element 10 according to an embodiment of the present invention. The oxygen separation membrane element 10 includes a bottomed cylindrical porous support 12 having a substantially cylindrical shape, an intermediate layer 16 wound around and fixed to an outer peripheral surface 14, and an electrolyte layer 18 provided on the intermediate layer 16. And a gas supply pipe 22 pierced into the bottomed hole 20 on the inner peripheral side of the porous support 12.

  The porous support 12 described above is configured, for example, as a whole with an outer diameter of 20 (mm) × inner diameter of 14 (mm) × length of about 750 (mm), as shown in FIG. A plurality of perforated disk-shaped parts 24 are provided with a shape in which they are stacked via a plurality of support columns 26. The plurality of perforated disk-like portions 24 are, for example, all configured in the same shape and the same size except for the portion constituting the bottom portion of the porous support 12, and the outer peripheral surface and inner peripheral surface thereof. Are located on one cylindrical surface.

  The above-mentioned bottomed hole 20 is configured by connecting through holes 28 formed in each of the perforated disk-like portions 24 with an appropriate interval in the axial direction. The plurality of support columns 26 disposed on the annular end surface 30 of the perforated disc-shaped portion 24 are spaced apart from each other in the circumferential direction of the annular end surface 30. Therefore, a plurality of through-holes 32 that are divided in the circumferential direction by a plurality of support columns 26 exist between the plurality of perforated disk-shaped portions 24. The through-hole 32 penetrates from the outer peripheral surface 14 of the porous support 12 to the bottomed hole 20, and as a result, the porous support 12 has the bottomed hole 20 penetrating in the axial direction and the outer periphery. A straight tubular hole penetrating linearly between the surface 14 and the surface 14 is provided.

  FIG. 3 is a diagram showing a support-integrated disc 34 that is a component of the porous support 12 described above. The pillar-integrated disk 34 includes the perforated disk-like portion 24 and six pillar portions 26 that are integrally provided on both annular end surfaces 30 and 30. The support portions 26 on both sides are provided at the same position in the circumferential direction. The perforated disk-like portion 24 has a size of an outer diameter of 20 (mm) × an inner diameter of 14 (mm) × a thickness of 1.7 (mm). Moreover, the support | pillar part 26 is the magnitude | size of about length 3 (mm) x width 1.6 (mm) x height 0.8 (mm), is extended along the radial direction of the perforated disc-shaped part 24, and the circumferential direction It is provided at intervals of 60 degrees. Therefore, the interval between the six support portions 26 provided on one annular end surface 30 is about 5.7 (mm) at the inner peripheral end and about 8.9 (mm) at the outer peripheral end.

  The porous support 12 is configured by laminating a plurality of strut-integrated disks 34 configured as described above at the circumferential positions where the strut portions 26 and 26 overlap each other and being joined to each other. It is a thing. Therefore, the straight tubular hole, that is, the through hole 32 provided in the porous support 12 has a rectangular shape with an inner peripheral side of about 5.7 (mm) × 1.5 (mm) and an outer peripheral side of 8.9 (mm) × 1.5 (mm). ) About a rectangle.

In addition, the above-mentioned support-integrated disc 24 includes, for example, a lantern such as La _0.6 Sr _0.4 Ti _0.3 Fe _0.7 O ₃ (hereinafter referred to as LSTF) or La _0.6 Sr _0.4 Zr _0.2 Fe _0.8 O ₃ (hereinafter referred to as LSZF). It consists of a system perovskite complex oxide. This column integrated disc 24 itself is a dense body and has a porosity of less than 1 (%). Therefore, the gas flow path leading from the bottomed hole 20 of the porous support 12 to the outer peripheral surface 14 is only the through-hole 32 formed by the perforated disk-like portion 24 and the column portion 26.

  Returning to FIG. 1, the electrolyte layer 18 is a dense film having a thickness of about 50 (μm) made of a lanthanum perovskite complex oxide such as LSTF or LSZF. The electrolyte layer 18 is preferably made of the same material or a similar material as the porous support 12. That is, when the porous support 12 is made of LSTF, the electrolyte layer 18 is also preferably made of LSTF. When the porous support 12 is made of LSZF, the electrolyte layer 18 is also made of LSZF. It is preferable to do. By doing so, there is no difference in the thermal expansion coefficient between the electrolyte layer 18 and the porous support 12 or it becomes sufficiently small, so that there is a possibility of damage due to a thermal history repeatedly given during manufacture and use. Reduced.

  The intermediate layer 16 has a thickness dimension of about 0.1 to 0.2 (mm), for example, and is made of, for example, the same material or a similar material as the electrolyte layer 18 and the porous support 12. The intermediate layer 16 is provided for the purpose of enabling the thin electrolyte layer 18 to be formed on the porous support 12 having the large through holes 32 as described above. Therefore, the intermediate layer 16 is configured to have a thickness that can maintain the shape of the intermediate layer 16 on the porous support 12, and the gas emitted from the through-hole 32 of the porous support 12 can be easily transmitted. Such a porous body has a pore diameter of, for example, about 0.1 to 10 (μm) and a porosity of 20 (%) or more.

  The gas supply pipe 22 is a dense body made of high-purity MgO having a purity of, for example, 95 (%) or more and having a porosity of less than 1 (%), for example, outer diameter 13.9 (mm) × inner diameter 10.5 (mm) × It has a length of about 1000 (mm). Therefore, the size of the space between the gas supply pipe 22 and the bottomed hole 20 of the porous support 12 is about 0.1 (mm), that is, a size sufficiently smaller than the through hole 32. One end of the gas supply pipe 22 located on the upper side in FIG. 1 protrudes from one end of the porous support 12, and the lower end (not shown) located on the lower side is located slightly away from the bottom of the porous support 12.

  The oxygen separation membrane element 10 is manufactured as follows, for example. In producing the gas supply pipe 22, first, for example, an electrofused magnesia powder having an average particle size of about 2 (μm) is prepared, and an appropriate organic binder and a dispersant are added thereto and kneaded. Prepare the clay. As the raw material powder, commercially available appropriate powders can be used. Next, this kneaded material is extruded using an extruder, for example, into a size of outer diameter 18 (mm) × inner diameter 14 (mm) × length 1200 (mm). After drying, this is baked at a temperature of about 1500 to 1800 (° C.), for example. Further, after the firing, the gas supply pipe 22 is obtained by polishing the outer peripheral surface to finish the desired outer diameter as described above.

  On the other hand, when the porous support 12 is manufactured, first, the LSTF or LSZF powder having an average particle diameter of about 1 (μm) (however, the same or similar material as the constituent material of the electrolyte layer 18 is used). Is prepared, and an appropriate organic binder and dispersant are added and mixed, and further granulated by an appropriate method such as spray granulation to obtain a granulated powder of about 60 (μm), for example. As the raw material powder, commercially available appropriate powders can be used. Next, this is powder press-molded at a pressure of about 150 (MPa), for example, and has a shape as shown in FIG. A molded body having a thickness dimension of about 2 (mm) and a thickness of the column portion 26 of about 1 (mm) is obtained. In addition, after shaping | molding, wet hydrostatic pressure pressurization (CIP) of about 150 (MPa) is further performed as needed.

  Next, the obtained molded body is fired in an air atmosphere. First, for example, the firing treatment is performed by decomposing organic substances by holding at a temperature of about 200 to 500 (° C.) for about 10 hours, and then raising the temperature to about 1000 to 1600 (° C.) and holding it for about 3 hours. Next, the obtained fired product is processed into a desired size by mechanical polishing. Thereby, the support | pillar integrated disc 34 shown in the said FIG. 3 is obtained.

  Next, a plurality of pillar-integrated discs 34 are sequentially inserted and stacked in the gas supply pipe 22 and fired at a temperature of about 1300 to 1600 (° C.) in the atmosphere, for example, to thereby obtain a plurality of pillars. The integrated disks 34 are joined together. At this time, the column-integrated disc 34 is arranged so that the column portions 26 are in the same circumferential position, that is, the column-integrated disc 34 positioned on the upper side is lower than the column unit 26 on the back surface. Are stacked so as to be supported by the column portion 26 of the column-integrated disk 34. Thereby, the porous support 12 shown in FIG. 2 is obtained. Although FIG. 2 shows a state in which the gas supply pipe 22 is not inserted, the gas supply pipe 22 is a constituent member of the oxygen separation membrane element 10 and can be left pierced during firing. Absent.

  At this time, the diameter of the bottomed hole 20 provided along the axial direction of the porous support 12 is slightly larger than the outer diameter of the gas supply pipe 22 as is apparent from the above-mentioned numerical values. Since a gap of about 0.1 (mm) is formed between them, the porous support 12 and the gas supply pipe 22 are in contact with each other but are not joined.

  Next, a separately prepared intermediate layer sheet is wound around the outer peripheral surface 14 of the obtained porous support 12 and subjected to a firing treatment. Furthermore, the electrolyte layer 18 is formed by applying a slurry on the formed intermediate layer 16 by dip coating and performing a baking treatment. Thereby, the oxygen separation membrane element 10 is obtained.

  In addition, the intermediate layer sheet is prepared, for example, LSTF or LSZF raw material having an average particle size of about 20 to 50 (μm) (however, using the same or similar material for the support), and a solvent, a binder, A plasticizer and a dispersing agent are added and mixed to prepare a slurry, which can be formed using, for example, a doctor blade method. What is necessary is just to determine a shaping | molding dimension suitably according to the magnitude | size of the intermediate | middle layer 16 to form. In addition, since the intermediate layer 16 needs to be porous, a coarser layer is used as compared with the raw material for manufacturing the pillar integrated disc 34.

  The slurry for forming the electrolyte layer 18 is, for example, mixed with LSTF or LSZF powder having an average particle size of about 1 to 2 (μm) by adding a solvent, a binder, a plasticizer, a dispersant, and the like. Prepare.

  As described above, by stacking the pillar-integrated disks 34 and performing the firing treatment, a straight tubular hole is formed between the perforated disk-like part 24 and the pillar part 26, and the porous support 12. Therefore, according to the present embodiment, the oxygen separation membrane element 10 having the porous support 12 having the straight tubular through-hole 32 can be easily obtained. When the oxygen separation membrane element 10 is used, an air electrode catalyst and a fuel electrode catalyst are respectively carried on the inner and outer peripheries thereof.

  The porous support 12 is manufactured by laminating a pillar integrated disk 34 in which a perforated disk-like part 24 and a pillar part 26 are integrally provided. Alternatively, the perforated discs and the struts constructed in the above can be alternately laminated and joined to form a porous support.

  The oxygen separation membrane element 10 of the present embodiment is configured by forming a dense electrolyte layer 18 on the outer peripheral surface of a porous support 12 having a gas diffusion performance having a straight tubular through hole 34 as described above. Therefore, the porous support 12 is preferably suppressed from regulating the oxygen transmission rate of the oxygen separation membrane element 10 as a whole. Therefore, the oxygen separation membrane element 10 having a high oxygen transmission rate corresponding to the constituent material and film thickness of the electrolyte layer 18 is obtained.

  The porous support 12, the intermediate layer 16, and the electrolyte layer 18 are preferably made of the same or similar materials from the viewpoint of adapting the thermal expansion coefficient and suppressing characteristic changes due to mutual reaction, but are made of different materials. You can also For example, it is preferable to use a raw material having high sinterability because the pillar-integrated disk 34 constituting the porous support 12 needs to be dense, but the intermediate layer 16 needs to be porous. For this reason, it is preferable to use a raw material having a sufficiently low sinterability. For example, if a part of the B-site element of LSTF and LSZF constituting the pillar integrated disc 34 is changed, an appropriate non-sinterable raw material can be obtained in the intermediate layer 16 within a range in which the thermal expansion coefficient is not largely changed. It is done.

  Evaluation results of the oxygen separation membrane element 10 will be described below together with comparative examples. Table 1 below summarizes the evaluation results. In Table 1, Examples 1 and 2 are oxygen separation membrane elements manufactured as described above, and the Comparative Example is the same as the Example except that the gap between the gas supply pipe and the porous support 12 is large. It is the comparative example which comprised. That is, the electrolyte layer of the comparative example was composed of about 50 (μm) LSTF. The “gas channel diameter” is the size of the straight tubular hole provided in the porous support 12, but in the present embodiment, the through hole 32 has a substantially rectangular shape with different sizes on the inner and outer circumferences as described above. Therefore, the height dimension of the through-hole 32, that is, the mutual interval between the perforated disk-like parts 24 was used. Further, the “porosity” is the porosity of the porous support 12 and was calculated by the ratio of the space in the portion between the outer peripheral surface and the inner peripheral surface. Further, the “gap size” is a mutual interval between the inner peripheral surface of the bottomed hole 20 of the porous support 12 and the outer peripheral surface of the gas supply pipe 22. “Oxygen permeation rate” refers to the flow rate of oxygen permeated through the electrolyte layer 18, the oxygen concentration in the supplied gas, and oxygen when air is supplied into the porous support 12 from the gas supply pipe 22 at 1000 (° C.) It calculated from the oxygen permeation | transmission part area of the separation membrane element. In both the examples and comparative examples, the constituent material of the electrolyte layer 18 was the same as the support material.

As shown in Table 1 above, in Examples 1 and 2 in which the gas supply pipe 22 is substantially in contact with the porous support 12 with a gap size of 0.1 (mm) or less, 22 (cc / min / cm ² ) Or as high as 26 (cc / min / cm ² ). On the other hand, the comparative example constructed in the same manner as the example except that the gap size was as large as 2.0 (mm) remained at about 15 (cc / min / cm ² ). The electrolyte layer 18 used in Examples 1 and 2 and the comparative example can obtain an oxygen permeation rate of about 3 (cc / min / cm ² ) when, for example, a self-supporting film of 500 (μm) is used. Thus, when the film thickness is about 50 (μm) as in the above examples and comparative examples, an oxygen transmission rate of at least about 30 (cc / min / cm ² ) should be obtained. Therefore, in the comparative example, only the ability of about 50 (%) is exhibited, but in Examples 1 and 2, it can be seen that the ability of 70 (%) or more is exhibited.

  4 to 6 are schematic diagrams for explaining the reason why the above difference occurs. 4 and 5 correspond to Examples 1 and 2, and FIG. 6 corresponds to a comparative example. FIG. 5 shows a gap between the porous support 12 and the gas supply pipe 22 in the AA cross section in FIG. In FIG. 4, the gap between the inner peripheral surface of the porous support 12 and the outer peripheral surface of the gas supply pipe 22 is compared with the straight tubular through-hole 32 from the bottomed hole 20 of the porous support 12 toward the outer peripheral surface 14. It is extremely small. Among the air supplied toward the bottom surface 36 of the porous support 12, the remainder except for the air that has permeated the peripheral wall of the porous support 12 and directed toward the intermediate layer 16 is the porous support 12 and the gas supply pipe. The gas is discharged from the opening end (the left end portion in FIG. 4) through the gap with 22. At this time, whether the air returns through the gap toward the opening end or into the intermediate layer 16 depends on which air has a higher flow resistance. In Examples 1 and 2, the diameter of the gas flow path of the through hole 32 is 1.5 (mm), whereas the size of the gap is as small as 0.1 (mm) or less, so that air tends to go to the through hole 32. As a result, a flow of air and oxygen as shown by arrows in FIG. 4 is formed, and a large amount of air reaches the outer peripheral surface of the intermediate layer 16, where it is dissociated by the air electrode catalyst, and oxygen ions pass through the electrolyte layer 18. Since it permeates, oxygen is recovered from the outer peripheral surface side of the oxygen separation membrane element 10 with a high oxygen permeation rate.

  On the other hand, in the comparative example, the through hole 32 has a size of about 1.5 (mm) as in the embodiment, whereas the gap between the porous support 12 and the gas supply pipe 38 is 2.0 (mm). About big. Therefore, the air supplied toward the bottom surface 36 tends to go to the open end of the porous support 12 as indicated by an arrow in FIG. 6, so that the gas flow path diameter of the porous support 12 is increased and the gas diffusion performance is increased. However, it is considered that this was not effectively utilized and the oxygen transmission rate was lowered.

  In short, according to the present embodiment, the porous support 12 having a straight tubular hole with high gas diffusion performance is used, and the gap between this and the gas supply pipe 22 is made sufficiently smaller than the straight tubular hole. Therefore, the air supplied from the gas supply pipe 22 is preferably directed to the intermediate layer 16 and a high oxygen transmission rate can be obtained.

  FIG. 7 is a perspective view showing a gas supply pipe 40 that can be used in place of the gas supply pipe 22 for the oxygen separation membrane element 10. A plurality of (for example, about 16) grooves 44 extending along the longitudinal direction and extending over the entire length are provided on the outer peripheral surface 42 of the gas supply pipe 40. The groove 44 has, for example, a width dimension of about 2.0 (mm) and a depth dimension of about 2.0 (mm). Therefore, as shown in FIG. 4, in the state where the gas supply pipe 40 is inserted into the porous support 12, air easily flows in the portion where the groove 44 is provided. Therefore, when the flow rate of air supplied toward the bottom surface 36 of the porous support 12 is large, there is an advantage that pressure loss can be suitably reduced by using such a gas supply pipe 40.

  In addition, since the gas supply pipe 40 as described above has a uniform cross-sectional shape, for example, it can be easily manufactured by an extrusion molding method. However, the gas supply pipe 40 is manufactured by cutting a rod-shaped molded body. There is no problem.

  FIG. 8 is a view showing a porous support 46 for constituting an oxygen separation membrane element of still another embodiment of the present invention in a state where the gas supply pipe 22 is inserted into a bottomed hole 48 on the inner periphery thereof. It is. The porous support 46 is made of a dense perovskite structure oxide like the porous support 12. A large number of through holes 52 having a circular cross section are opened on the outer peripheral surface 50, and these through holes 52 are straight tubular holes penetrating linearly toward the bottomed hole 48. For this reason, air easily passes from the bottomed hole 48 toward the outer peripheral surface 50. Each of the through holes 52 has an opening diameter of about 1 (mm), for example, and the porosity of the porous support 46 is, for example, about 30 (%).

  Therefore, even when the porous support 46 as described above is used, the gas supply pipes 22 and 40 have a high porosity and a large number of through holes 52 that are straight tubular holes. When the oxygen separation membrane element is configured, a high oxygen transmission rate can be obtained.

  In addition, such a porous support body 46 can be manufactured by, for example, forming the through holes 52 by machining after being molded by CIP or the like.

  FIG. 9 is a view showing a porous support 54 of still another embodiment. The porous support 54 has a shape in which a large number of fins 58 project from a cylindrical outer peripheral surface 56. Each of the fins 58 is formed over the entire length of the porous support 54 with a width dimension of about 2.5 (mm) and a height dimension of about 2 (mm), for example. The interval is, for example, about 2.5 (mm).

  Such a porous support 54 can constitute an oxygen separation membrane element, for example, by providing the intermediate layer 16 and the electrolyte layer 18 in the same manner as the porous support 12 on the outer periphery thereof. At this time, a gas flow path extending along the longitudinal direction of the porous support 54 is formed between the fins 58, and the gas flow path faces the inner peripheral surface of the intermediate layer 16. If the gap between the tube 22 and the bottomed hole 60 is made sufficiently small, the supplied air is preferably sent toward the inner peripheral surface of the intermediate layer 16. Therefore, in this embodiment, the flow path of the supplied air is different from that in each of the embodiments described above, but a high oxygen transmission rate can be obtained in the same manner.

  In particular, in the case of this shape, since a relatively large gas flow path can be secured between the fins 58, pressure loss is unlikely to occur, so there may be no gap between the gas supply pipe 22 and the bottomed hole 60 at all. On the contrary, that is preferred.

  Table 2 below shows the evaluation results of the oxygen separation membrane element using the porous support 54 having the shape as described above. In this embodiment, the support material is MgO having a high purity (for example, 95% or more), the electrolyte layer 18 is LSTF, and the film thickness is about 50 (μm). Other conditions that are not explicitly described are the same as those in the above-described embodiment. As shown in Table 2, it was confirmed that even when MgO was used as the support material, an extremely high oxygen transmission rate was obtained.

  In addition, although the porous support body 54 provided with the above shapes can be manufactured by extrusion molding, for example, other manufacturing methods may be used. However, since MgO is inferior in diffusion bonding property as compared with the perovskite structure oxide as described above, it is difficult to adopt a manufacturing method in which the pillar-integrated disks 34 are laminated and bonded as described above.

  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 oxygen separation membrane element of one Example of this invention. It is a perspective view which shows the porous support body which comprises the oxygen separation membrane element of FIG. It is a perspective view which shows the support | pillar integrated disc which is one component of the porous support body of FIG. It is sectional drawing explaining the flow of the gas in the oxygen separation membrane element of FIG. It is a figure which shows the AA cross section of FIG. It is sectional drawing corresponding to FIG. 4 for demonstrating the flow of the gas in the conventional oxygen separation membrane element. It is a figure which shows the gas supply pipe | tube for comprising the oxygen separation membrane element of the other Example of this invention. It is the example of a combination of the support body and gas supply pipe | tube for comprising the oxygen separation membrane element of other Example of this invention. It is the example of a combination of the support body and gas supply pipe | tube for comprising the oxygen separation membrane element of other Example of this invention.

Explanation of symbols

10: oxygen separation membrane element, 12: porous support, 14: outer peripheral surface, 16: intermediate layer, 18: electrolyte layer, 20: bottomed hole, 22: gas supply pipe, 24: perforated disk-shaped part, 26: strut portion, 28: through hole, 30: annular end surface, 32: through hole, 34: strut integrated disc, 36: bottom surface, 38: gas supply pipe, 40: gas supply pipe, 42: outer peripheral surface, 44: groove, 46: porous support, 48: bottomed hole, 50: outer peripheral surface, 52: through hole, 54: porous support, 56: outer peripheral surface, 58: fin

Claims (4)

A bottomed cylindrical support having a dense electrolyte layer having a cylindrical shape and a plurality of gas flow paths for supplying air to the inner peripheral surface of the electrolyte layer and supporting the electrolyte layer from the inner peripheral side An oxygen separation membrane element comprising a body and a gas supply pipe inserted from the open end to the inner peripheral side for supplying gas to the bottom of the support,
An oxygen separation membrane element, wherein a distance between the inner peripheral surface of the support and the outer peripheral surface of the gas supply pipe in the radial direction is smaller than the size of the gas flow path.   The plurality of gas flow paths are straight tubular holes provided in the peripheral wall of the cylindrical support so as to linearly penetrate from the inner peripheral surface to the outer peripheral surface, and the mutual intervals are the gas flow of the straight tubular holes 2. The oxygen separation membrane element according to claim 1, wherein the oxygen separation membrane element is smaller than a maximum value of a passing dimension perpendicular to the direction.   The support body has a cylindrical base portion extending along one direction and a plurality of ribs protruding from the outer peripheral surface of the base portion so as to be spaced apart from each other in the circumferential direction and extending along the longitudinal direction of the base portion. 2. The oxygen gas according to claim 1, wherein the plurality of gas flow paths are formed between the plurality of rib-shaped portions, and the mutual interval is smaller than the height dimension of the rib-shaped portions. Separation membrane element. The support is of the general formula Ln _1-x Ae _x MO ₃ (where Ln is at least one selected from lanthanoids, Ae is at least one selected from Sr, Ca, Ba, M is Mg, Mn, Ga, Ti , Co, Ni, Al, Fe, Cu, In, Sn, Zr, V, Cr, Zn, Ge, Sc, Y perovskite composite oxide represented by 0 ≦ x ≦ 1) It consists of
The oxygen separation membrane element according to any one of claims 1 to 3, wherein at least an outer peripheral surface of the gas supply pipe is made of magnesium oxide (MgO).

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