JP2006102662A - Hydrogen permeation separation material and production method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydrogen permeation separation material with superior durability, heat resistance and workability, and enhanced strengths, while further thinning by improving strengths of a hydrogen permeation separation membrane which is a constituent, reducing cost, improving hydrogen permeation speed, and achieving high hydrogen concentration by reducing pin holes. <P>SOLUTION: In the hydrogen permeation separation material 1, the hydrogen permeation separation membrane 3 comprising a rolled multi-layered structure by diffusion bonding of a Pd layer 8, a Ta layer 9 and a Pd outer layer 10, each having extremely few pin holes, are diffusion-bonded on one surface of a porous metal 2 having communicating fine holes. Thus, the material allows the permeation of highly concentrated hydrogen, has superior workability, can be thinned by enhanced strengths, is inexpensive, and has a high hydrogen permeation speed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a hydrogen permeable separation material used for separating hydrogen gas from a mixed gas of hydrocarbon gas such as methane gas and water vapor to produce high-purity hydrogen gas, and a method for producing the same.

  Combining a fuel cell with a hydrogen generation system that generates hydrogen by reforming gasoline, city gas, methane, liquid hydrocarbons such as methanol and ethanol, or hydrocarbons containing oxygen elements with water vapor etc. Such a system is expected as a portable power source, a stationary power source, a power source mounted on an electric vehicle, and the like.

  However, the reformed gas contains about 1% carbon monoxide gas, which has a problem of poisoning platinum which is an electrode catalyst of a solid polymer fuel cell. In the case of a solid polymer type fuel cell, since the carbon monoxide gas is also poisoned with platinum by about 50 ppm, it is necessary to reduce the carbon monoxide gas concentration to 10 ppm or less.

  As a reduction method thereof, a hydrogen separation method from a hydrogen mixed gas using Pd or an alloy containing Pd that selectively permeates only hydrogen is conventionally known. Here, when Pd or Pd alloy is used as a hydrogen separator, it is usually processed into a thin film.

  For example, when a cylindrical tube is made of a Pd film or a Pd alloy film, one end of the tube is sealed and welded, and pressurized raw material hydrogen gas is supplied to the outside of the tube. The hydrogen molecules that are dissociated into atoms form a solid solution with Pd and are taken into Pd.

  As described above, the incorporated hydrogen atoms diffuse from the outside of the high pressure tube to the low inside due to the hydrogen partial pressure inside and outside the tube, and become hydrogen molecules again on the inside surface. Many impurities contained in the raw material hydrogen gas do not react with Pd, and therefore remain outside the tube, thereby purifying the hydrogen.

  Conventionally, a hydrogen purifier using a single Pd alloy tube has been put into practical use. However, the thickness of the tube used is 80 μm or more, and the hydrogen permeation amount is small and expensive.

  On the other hand, a method has been proposed in which a Pd alloy film is formed on the surface of a ceramic porous support by 20 μm by a plating method (see, for example, Patent Document 1).

  In this method, the mechanical strength is increased by coating a Pd film on the outer surface of a porous support made of ceramic.

  However, in the conventional method of forming a Pd film or a Pd alloy film (hereinafter simply referred to as a Pd alloy film) on the surface of a porous support made of ceramic by a plating method, if the Pd alloy film becomes thin, it becomes like a pinhole. More leaks. As a result, the purity of hydrogen obtained when the purity of the raw material hydrogen gas is low, for example, the purity is 99.99% when the thickness of the Pd alloy film is 20 μm, 99.9% when the thickness is 10 μm, and 99% when the thickness is 5 μm. There is a problem that the purity of hydrogen is lowered.

  Also, since many of the porous supports made of ceramic have a lower coefficient of thermal expansion than the Pd alloy film, the Pd alloy film coated on the outer peripheral surface of the tubular porous support peels off when used at a high temperature. In some cases, the source hydrogen gas leaks to the purified hydrogen side.

  Furthermore, when a hydrogen permeable membrane device formed by forming a Pd alloy membrane on the porous support surface is attached to a flange or the like to assemble a hydrogen permeable membrane device, or due to vibration during use, a mechanical shock is applied to the outer surface of the hydrogen permeable membrane. ， Friction may damage the hydrogen permeable membrane.

  In addition, when a difference in temperature distribution occurs in an apparatus using a plurality of tubular hydrogen permeable membranes, thermal expansion of some hydrogen permeable membranes increases because there is no heat conduction between the hydrogen permeable membranes. There is a problem that high stress is generated at the joint between the hydrogen permeable membrane and the flange and the airtightness of the joint is impaired.

  Therefore, after that, instead of the conventional porous support made of ceramic, the mechanical strength is strong, the torsional strain and vibration are strong, the thermal conductivity is high, and the difference between the thermal expansion coefficient and the Pd alloy film is small. A porous support made of a metal having features such as excellent durability, easy hermetic sealing such as welding at high temperature, and no gas leakage from the sealed portion has been studied.

  Here, many ideas have been made to obtain a metal porous support having a smooth surface. Specifically, the pore diameter is controlled by press molding foam metal. In addition, those that are sprayed or plated, those that laminate and sinter a plurality of SUS316 metal fiber non-woven fabrics or wire meshes, and that are further vapor-deposited (see, for example, Patent Document 2), or those that are made of SUS316 There has been proposed a method of forming a porous metal support having a smooth surface by reducing the pores with a ceramic sprayed porous body (for example, see Patent Document 3).

  Furthermore, a Pd alloy film prepared in advance by plating and vapor deposition and a fine powdered metal powder are heated and sintered. A porous layer with a thin skeleton and a small pore size and a coarse powdered metal powder are heated and sintered. A method of forming a hydrogen permeable membrane by joining a porous metal plate composed of two or more porous layers having a large skeleton and a large pore size formed by (For example, see Patent Document 4).

  However, in the case of the conventional method for forming a Pd alloy film on the surface of a metal porous support, the entire process is performed through a special treatment process such as vapor deposition or thermal spraying in order to obtain a metal porous support having a smooth surface. There was a problem that there were many numbers and the manufacturing method was complicated.

  Moreover, in the thing of patent document 4, since the process which peels and peels this off after producing Pd alloy film by plating and vapor deposition is carried out, Pd alloy film is directly plated or vapor-deposited on a metal porous support body. Compared with the method to do, a process becomes complicated. Further, when the thickness is 10 μm or less, there is a problem that the yield is poor and the cost is high.

  In addition, as with the porous support using the ceramic material, which is the first problem, when the Pd alloy film becomes thinner, leakage from things such as pinholes increases, and as a result, the purity of the raw material hydrogen gas increases. If it is low, the purity of the hydrogen after purification is, for example, 99.99% when the thickness of the Pd alloy film is 20 μm, 99.9% when it is 10 μm, and 99% when it is 5 μm. Is left behind.

  In short, it is very difficult to form a defect-free Pd alloy film on the surface of a porous support having innumerable fine pores, and a defective product is likely to be produced, resulting in poor yield, and on the other hand, defect-free Pd If the film thickness is increased in order to form an alloy film, the hydrogen permeation performance deteriorates as a result, and sufficient performance is not exhibited, the hydrogen separation and purification efficiency deteriorates, and the cost increases due to the thick film thickness. The problem of becoming high arises.

In order to solve such a problem as much as possible, recently, after forming a Pd film or a Pd alloy film on one of the porous bodies sintered with metal powder, a cold is applied to the surface layer of the Pd film or Pd alloy film. There is a manufacturing method characterized by performing plastic working (see, for example, Patent Document 5).
JP-A-62-273030 JP-A-6-304457 JP-A-6-91144 Japanese Unexamined Patent Publication No. 2000-5580 JP 2002-355537 A

  However, even in the method described in Patent Document 5, the hydrogen concentration that permeates is higher than before, but the concentration when supplying to the intended polymer electrolyte fuel cell is 10 ppm. Is not satisfied.

  This is because the formation method of Pd on the porous body is electroless plating, so that there are pinholes or micro cracks caused by cold plastic working after simply forming a Pd film. It is also considered that the Pd film was formed by the electroless plating method and thus cracks occurred during cold plastic working.

  In any case, in order to improve the concentration of permeating hydrogen, it is considered that the thickness of the Pd film needs to be increased, and there is a problem that the cost increases.

  In addition, although the Pd film has a thickness of 5 μm, when electroless plating is performed on the porous body, a relatively large porous body such as a sintered metal body also has a Pd film on the surface of the pores inside the surface pores. Plating is performed, and then the pores are filled, and the Pd film covers the porous body surface. That is, such a portion is locally generated, and the amount of Pd to be used is larger than the apparent Pd film thickness, resulting in high cost, and the hydrogen permeation amount is reduced because the film thickness is thick at that portion. .

  Therefore, it has high mechanical strength, resistance to torsional strain and vibration, high thermal conductivity, and small difference in thermal expansion coefficient from Pd alloy film, so it has good temperature cycle durability and is hermetically sealed such as welding at high temperature. In addition to having features such as easy and no gas leakage from the seal part, the Pd film on the surface of the support is made denser than the plating method, thereby improving the concentration of permeating hydrogen by reducing pinholes, etc. The hydrogen permeation separator having a support capable of reducing the cost and increasing the hydrogen permeation amount due to the reduction of the Pd amount by suppressing the inflow amount of the Pd membrane into the pores on the surface of the support which is a porous body Is required.

  In order to solve such a problem, the present invention, in constituting a hydrogen permeation separator, a hydrogen permeation separation membrane that permeates hydrogen is diffusion bonded to at least one surface of a porous metal having pores that communicate with each other. This results in diffusion bonding to the porous metal surface using a hydrogen permeable separation membrane with no or very little pinholes. As a result, the amount of gas other than hydrogen can be reduced, and the permeated hydrogen concentration can be greatly reduced. Can be expensive. Further, when viewed microscopically, since the membrane is formed so as to cover the opening of the surface pores of the porous metal, the amount of the hydrogen permeable separation membrane entering the pores can be reduced, and the Pd of the hydrogen permeable separation membrane to be used is reduced. The amount can be reduced.

  According to the present invention, the hydrogen permeation separator has high mechanical strength, torsional strain, resistance to vibration, high heat conduction, and a small difference in thermal expansion coefficient from the Pd alloy film, so that the durability of the temperature cycle is good. In addition to having the same features as conventional ones such as easy sealing such as welding at high temperature and no gas leakage from the seal part, the hydrogen permeable separation membrane on the surface of the support has pinholes compared to the plating method. By being able to reduce, the concentration of permeating hydrogen can be improved, and the reliability can be improved by preventing damage by improving the strength of the hydrogen permeable membrane, and the thickness can be reduced and the cost can be reduced due to the reduction in the amount of material used. Furthermore, by suppressing the inflow amount of the Pd membrane as a hydrogen permeation separation membrane into the pores on the surface of the support, which is a porous body, it is possible to reduce the cost associated with the reduction of the Pd amount. Hydrogen permeation with improved permeation In which the separation material is obtained.

  According to the first aspect of the present invention, a hydrogen permeable separation membrane that permeates hydrogen is diffusion bonded to at least one surface of a porous metal having pores that communicate with each other.

  As a result, diffusion bonding to the surface of the porous metal using a hydrogen permeation separation membrane with no or very little pinholes can be achieved, the amount of gas permeation other than hydrogen can be reduced, and the concentration of permeated hydrogen can be greatly increased. . Further, when viewed microscopically, since the membrane is formed so as to cover the opening of the surface pores of the porous metal, the amount of the hydrogen permeable separation membrane entering the pores can be reduced, and the Pd of the hydrogen permeable separation membrane to be used is reduced. The amount can be reduced.

  According to a second aspect of the present invention, the hydrogen permeation separation membrane of the hydrogen permeation separation material is a multilayer structure membrane composed of a plurality of layers.

  As a result, the strength of the hydrogen permeable separation membrane is improved, and a decrease in the concentration of permeated hydrogen due to breakage can be suppressed. In addition, since the number of layers inside the hydrogen permeable separation membrane is increased to two or more, even if there are pinholes in two adjacent layers, the pinholes in the opposing layers at the joint surface between the two adjacent layers There is little possibility that they communicate with each other, and as a result, it is possible to reduce the possibility that a gas other than hydrogen will pass through the hydrogen permeable separation membrane by the pinhole penetrating the membrane.

  According to a third aspect of the present invention, the hydrogen permeation separation membrane is a multilayer comprising a plurality of stacked metal layers made of a metal having a large amount of hydrogen storage, and Pd layers provided on both surfaces of the plurality of stacked metal layers. It is a structure film.

  Since the Pd is more expensive than the metal generally used for the metal layer and has a slower hydrogen diffusion rate, the Pd layer or the Pd alloy layer exists only in the outermost layer of the multilayer film and is used as a catalyst having hydrogen molecules as atoms. Thus, the use amount of the Pd film can be reduced, and a multilayer structure can be used to reduce the thickness of the Pd film along with the improvement in strength. The use amount of the Pd film can be further reduced, and high performance can be maintained and inexpensive.

  The invention described in claim 4 is such that the layer having the junction with the porous metal in the hydrogen permeable separation membrane is set thicker than the other layers.

  As a result, the strength of the joint between the porous metal and the hydrogen permeable separation membrane layer, which has a small joint area compared to the area of the other joint and has a reduced strength, can be increased. Therefore, the material cost of the hydrogen permeable separation membrane can be reduced.

  According to a fifth aspect of the present invention, the metal constituting the metal layer of the hydrogen permeable separation membrane is a high melting point transition metal having a body-centered cubic structure.

  As a result, the high melting point transition metal having a body-centered cubic structure absorbs hydrogen well and thus has high hydrogen permeation performance, and has an effect that it is suitable as a material for the central portion of the hydrogen permeation separation membrane.

  Further, when this hydrogen permeable separation membrane is used for separating hydrogen gas from a mixed gas of hydrocarbon gas such as methane gas and water vapor to produce high purity hydrogen gas, a high temperature reactor of about 500 ° C. Since the hydrogen permeable separation membrane is disposed therein, the use of a metal having a high melting point as a metal having high hydrogen permeation performance is advantageous in terms of heat resistance.

  In a sixth aspect of the present invention, the metal constituting the metal layer of the hydrogen permeable separation membrane is any one of Ta, Nb, and V.

  Since these Ta, Nb, and V are high melting point transition metals having high hydrogen permeation performance and a body-centered cubic structure, Ta, Nb, V, Ta alloy, Nb alloy, and V alloy are the centers of hydrogen permeable separation membranes. It has the effect | action that it is suitable as a material of a part. Further, Ta, Nb, V, Ta alloy, Nb alloy, and V alloy have an effect that the metal layer can be easily thinned by rolling because the tensile strength is higher than that of Pd and the rollability is good.

  According to a seventh aspect of the present invention, in the hydrogen permeation separator, each layer which is a multilayer structure film of the hydrogen permeation separation film is diffusion bonded, and the multilayer structure film is rolled.

  As a result, the hydrogen permeable separation membrane has no pinholes or very few layers are laminated and diffusion-bonded, so that the gas permeation amount other than hydrogen in each layer is reduced, and the two adjacent layers are pinned. Even if there is a hole, there is little possibility that the pinholes of the opposing layers communicate with each other at the joint surface of the two adjacent layers. The possibility of passing through the separation membrane can be reduced, and the hydrogen concentration that permeates is very high. In addition, when viewed microscopically, the membrane is formed so as to cover the openings of the surface pores of the porous metal, so that the amount of hydrogen permeable separation membrane entering the pores can be reduced, and the amount of hydrogen permeable separation membrane used can be reduced. Further, the strength of the hydrogen permeation separation membrane can be improved, and the film thickness can be reduced accordingly, so that the hydrogen permeation amount can be increased and the amount of material used for the hydrogen permeation separation membrane can be reduced.

  According to the eighth aspect of the present invention, a hydrogen permeable separation membrane that occludes or permeates hydrogen is diffusion bonded to at least one surface of a porous metal.

  This allows diffusion bonding of the porous metal surface using a hydrogen permeation separation membrane with no or very little pinholes, so that the amount of gas permeation other than hydrogen can be reduced and high hydrogen concentration can be permeated. Since the membrane is formed so as to cover the opening of the surface pores of the porous metal when viewed microscopically, the amount of the hydrogen permeable separation membrane entering the pores can be reduced, and the hydrogen permeable separation membrane Therefore, it is possible to easily produce a hydrogen permeation separation material that can reduce the amount of use.

  According to the ninth aspect of the present invention, a hydrogen permeation separation membrane manufactured by diffusion bonding and rolling a plurality of materials having hydrogen permeation performance is simultaneously or diffusion bonded with a porous metal.

  As a result, the gas permeation amount other than hydrogen of each layer is reduced, and even if there are pinholes in two adjacent layers, the pinholes of the opposing layers are formed at the bonding surface of the two adjacent layers. Since there is little possibility of communication, the possibility of gas other than hydrogen passing through the hydrogen permeable separation membrane can be reduced by the pinhole penetrating the membrane, and the concentration of permeated hydrogen becomes very high. In addition, when viewed microscopically, the membrane is formed so as to cover the openings of the surface pores of the porous metal, so that the amount of hydrogen permeable separation membrane entering the pores can be reduced, and the amount of hydrogen permeable separation membrane used can be reduced. The hydrogen permeation separation membrane can be reduced in strength, and the film thickness can be reduced accordingly, so that the amount of hydrogen permeation increases and the amount of material used for the hydrogen permeation separation membrane can be reduced. Such a hydrogen permeation separator that can permeate and separate hydrogen at a high performance and at a high concentration can be manufactured.

  In the invention according to claim 10, the diffusion bonding is performed after removing the oxide film on the diffusion bonding surface when performing the diffusion bonding.

  Thereby, the inhibition of diffusion bonding can be prevented, diffusion bonding can be easily performed, and further, the hydrogen permeation of the bonding surface can be prevented, and a high-performance hydrogen permeation separator can be manufactured.

  The invention according to claim 11 performs diffusion bonding in an atmosphere containing no oxygen or in a very small concentration.

  Accordingly, inhibition of diffusion bonding can be prevented, thereby preventing hydrogen permeation from being inhibited, and a higher performance hydrogen permeation separator can be manufactured.

  In the invention according to claim 12, in the formation of the hydrogen permeation separation membrane, two Pd foils and a plurality of metal foils made of a metal having high hydrogen permeation performance are placed between the two Pd foils. A plurality of metal foils are superposed so that they are positioned, and the superposed foils are rolled simultaneously with diffusion bonding or after diffusion bonding.

  As a result, Pd is more expensive than the metal generally used for the metal layer and has a slower hydrogen diffusion rate. Therefore, the Pd layer or the Pd alloy layer exists only in the outermost layer of the multilayer film and is used as a catalyst having hydrogen molecules as atoms. As a result, the amount of Pd film used can be reduced, and a multilayer structure can be used to reduce the thickness of the Pd film, so that the amount of Pd film used can be further reduced, maintaining high performance and being inexpensive. A hydrogen permeation separator can be produced.

  In the invention of claim 13, in the manufacture of the hydrogen permeation separator, the diffusion bonding is performed by hot pressing in vacuum after laminating.

  Accordingly, by hot pressing the stacked foils in a vacuum, the stacked foils can be diffusion-bonded while suppressing formation of an oxide film on the surface of the metal foil (layer).

  In the invention described in claim 14, the thickness of the hydrogen permeable separation membrane is adjusted by adjusting the number of the metal foils to be overlapped.

  Accordingly, the thickness of the hydrogen permeable separation membrane can be easily changed while ensuring a necessary and sufficient thickness of the Pd layer without waste by increasing / decreasing the number of metal foils to be overlapped.

  According to the fifteenth aspect of the present invention, by adjusting the number of metal foils to be superimposed, the ratio of the thickness of the plurality of metal layers stacked in the hydrogen permeable separation membrane to the thickness of the Pd layer is adjusted. is there.

  By this, by increasing or decreasing the number of metal foils to be stacked and adjusting the rolling as necessary, it is possible to prepare a plurality of stacked metal layers in the hydrogen permeable separation membrane without preparing various types of metal foils having different thicknesses. The ratio between the thickness of the Pd layer and the thickness of the Pd alloy layer can be easily changed.

  The invention described in claim 16 uses a high melting point transition metal having a body-centered cubic structure as the metal constituting the metal foil in the production of the hydrogen permeation separator.

  Because this is a material with high heat resistance and a large amount of solid solution of hydrogen, in order to separate the hydrogen gas from the mixed gas of hydrocarbon gas such as methane gas and water vapor to produce high purity hydrogen gas A hydrogen permeation separator suitable for installation in a high-temperature reactor at around 500 ° C. as in the case of use can be produced.

  In the invention described in claim 17, the metal constituting the metal foil is any one of Ta, Nb, and V.

  As a result, Ta, Nb, V, Ta, Nb, and V are high melting point transition metals having high hydrogen permeation performance and a body-centered cubic structure, and have higher tensile strength and better rolling properties than Pd. Therefore, it is possible to produce a hydrogen permeation separator that has high heat resistance, good hydrogen permeation performance, and can be easily formed into a thin film.

  According to an eighteenth aspect of the present invention, in the hydrogen permeation separator, the hydrogen permeation separation membrane is installed so that hydrogen permeates from the opposite side of the surface where the hydrogen permeation separation membrane is diffusion bonded to the porous metal.

  As a result, even if the hydrogen permeable separation membrane breaks, it may remain in the pores of the porous metal, and in this case, it can be suppressed from flowing out together with the permeated hydrogen. For example, when permeated hydrogen is used as fuel for a fuel cell, problems due to contamination of foreign matter into the fuel cell can be reduced.

  According to a nineteenth aspect of the present invention, the hydrogen permeation separation material is tubular, and a hydrogen permeation separation membrane is positioned inside the tube.

  As a result, the inner surface of the tube is smaller than the outer surface of the tube, so when installing hydrogen permeation separators with the same film thickness, installing them on the inner side of the tube results in the same film thickness, that is, the same hydrogen permeation. Performance can be maintained and the amount of hydrogen permeable separation membrane used can be reduced.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, about the same structure as the past, the same code | symbol is attached | subjected and detailed description is abbreviate | omitted. Further, the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 is a cross-sectional view of a hydrogen permeation separator in Embodiment 1 of the present invention.

  In FIG. 1, a hydrogen permeable separation material 1 is composed of a porous metal 2, a hydrogen permeable separation membrane 3, and a seal member 4.

  The porous metal 2 is made of a metal having relatively excellent heat resistance, corrosion resistance, etc., such as stainless steel, Inconel, and Hastelloy, and is formed in a circular flat plate. And this porous metal 2 consists of the joint surface 5 of the surface which forms a circle | round | yen, the outer surface 6 which is a circular surface of a joint surface, and the sealing surface 7 which is an outer peripheral surface, and inside is a joint surface. There are a large number (numerous) of pores that connect the outer surface 5 with the outer surface 6.

  The hydrogen permeable separation membrane 3 has a multilayer structure, and is composed of a palladium Pd layer 8, a tantalum Ta layer 9, and a palladium Pd outer layer 10, which is a thin film compared to the Pd layer 8. An approximately equivalent film having a diameter larger than the diameter of the solid metal 2 is joined by diffusion bonding so as to be centered on each circle.

  The sealing member 4 is formed in a circular donut shape, and forms an inner circumferential surface 11 that is a circumferential surface portion of the inner circle located in the donut-shaped cavity, and a donut that forms a circle that becomes a donut-shaped top surface. It consists of a circular surface 12.

  The hydrogen permeation separation membrane 3 is diffusion bonded to the bonding surface 6 of the porous metal 2 with the same diameter center on the circular surface of the Pd layer 8 opposite to the surface bonded to the Ta layer 9, and other portions. And the donut circular surface 12 of the sealing member 4 is joined with the same diameter center.

  Further, the inner circumferential surface 11 of the sealing member 4 and the sealing surface 7 of the porous metal 2 are joined by diffusion, welding, or the like, and the Ta layer in the Pd outer layer 10 of the hydrogen permeation separation material 1 by the casing material 12. 9 is sealed so that the gas in contact with the portion that faces the joint surface 9 is not in direct contact with the gas in contact with the outer surface 6 of the porous metal 2.

  The operation and action of the hydrogen permeable separation material configured as described above will be described below.

  The pressure of the gas existing on the outer surface 6 of the porous metal 2 is set to be lower than the atmospheric gas in the portion facing the Pd outer layer 10, and although not shown, carbonization of city gas, propane gas, kerosene, etc. Gas after reforming to produce hydrogen from hydrogen fuel, pyrolysis gas obtained by pyrolyzing organic matter such as coal and biomass, tar and reforming low molecular gas, organic carbon A mixed gas such as a gas after reacting with water vapor is brought into contact with the Pd outer layer 10 to separate only hydrogen from the mixed gas.

  Here, hydrogen separation from a mixed gas when hydrogen, methane, carbon dioxide, and carbon monoxide are generated when methane is reformed with steam will be described.

  In the mixed gas that is in contact with and adsorbed on the surface of the Pd outer layer 10, hydrogen dissociates and becomes hydrogen atoms at a lower energy than other metals due to the characteristics of palladium that is a constituent material of the Pd outer layer 10. Through the inside, it passes through the Ta layer 9 and the Pd layer 8 and penetrates to the joint surface of the Pd layer 8 with the porous metal 2 by diffusion due to the pressure concentration difference.

  And in the joint surface with the porous metal 2 of the Pd layer 8, it is exposed to the Pd layer 8 surface other than the part joined to the metal part of the porous metal 2, that is, the pore of the porous metal 2. On the surface of the Pd layer 8, hydrogen atoms are molecularized and become hydrogen gas that flows through the pores of the porous metal 2 and permeates from the pores of the outer surface 6 to the outside. In this way, only hydrogen permeates the hydrogen permeable separation membrane and separates high-concentration hydrogen from the mixed gas.

  Next, the manufacturing method of the hydrogen permeable separation material in this Embodiment is demonstrated.

  In the manufacturing method of the hydrogen permeable separation membrane 3 in the present embodiment, two Pd foils having a thickness of 9 to 20 μm and one sheet having a thickness of 50 to 500 μm obtained by immersing in an aqueous solution of hydrogen fluoride to remove the oxide film. Laminate Ta foil so that the Ta foil is positioned between two Pd foils, and pressurize (hot press) through an alumina plate in vacuum (about 6 Pa) at about 900 ° C. for 3 hours. Then, the hydrogen permeable separation membrane 3 having a thickness of 25 μm, 35 μm, 50 μm, and 100 μm is manufactured by rolling.

  At this time, one of the two Pd foils is thicker than the other.

  Then, after the porous metal 2 and the hydrogen permeable separation membrane 3 are degreased and deoxidized with plasma etching or an acid aqueous solution, the hydrogen permeation is immediately performed so that the thick Pd foil side contacts the bonding surface 5 of the porous metal 2. The separation membranes 3 are stacked and diffusion-bonded by applying pressure (hot pressing) through an alumina plate at about 900 ° C. in a vacuum (about 6 Pa) for 3 hours.

  At this time, it is preferable to perform rolling so that the Pd layer has a thickness of 0.1 to 10 μm.

  When only these hydrogen permeable separation membranes 3 were subjected to a hydrogen permeation test at 500 ° C., the hydrogen permeable performance was better as the film thickness was reduced. It could be confirmed.

  The hydrogen permeation separation membrane having a thickness of 50 μm in the present embodiment had a hydrogen permeation performance approximately twice as high as that of PdAg (23 wt% alloy) having a thickness of 50 μm.

  In the present embodiment, a laminated film of Pd and Ta is used for the hydrogen permeation separation membrane 3, but a Pd alloy and a Ta alloy may be used, or a laminated alloy film or a single alloy film. Many metal films such as films can be used. In this case, it is further improved if materials having good compatibility of diffusion bonding between the porous metal 2 and the hydrogen permeation separation 3 are selected.

  From the above, when the hydrogen permeable separation membrane 3 is formed by plating or the like, it is not dense. Therefore, in order to reduce pinholes in order to maintain the hydrogen permeation concentration, it is necessary to increase the film thickness. However, in the first embodiment, since the surface of the porous metal 2 is diffusion-bonded by using the hydrogen permeation separation membrane 3 which has no pinholes or very few originally, the porous metal 2 is formed by plating or the like. In the case where the hydrogen permeation separation membrane 3 is formed with a relatively small pinhole as compared with the relatively non-dense hydrogen permeation separation membrane 3, the same hydrogen permeation concentration as that formed by plating is used. In the present embodiment, it is possible to reduce the thickness, the amount of hydrogen permeation separator 1 used can be reduced, and the hydrogen permeation amount per unit time, that is, the hydrogen permeation rate can be increased if the thickness of the hydrogen permeation separation membrane 3 is increased. You can do it faster because it gets slower and faster as you get thinner.

  Further, when viewed microscopically, a film is formed so as to cover the surface pores of the porous metal 2, that is, in the case of plating or the like, at least the pores of the porous metal 2 are plated. The permeation membrane material may be buried deep in the pores.

  In this case, there is no problem in the permeated hydrogen concentration, but the amount of hydrogen permeation separator increases, and the hydrogen permeation separation membrane 3 exposed in the pores of the porous metal 2 permeates hydrogen. Therefore, the portion exposed to the pores is partially thickened. At this time, even if the portion of the hydrogen permeable separation membrane 3 in contact with the substrate of the porous metal 2 is thin but the portion exposed to the pore space of the porous metal 2 is thick, the hydrogen permeation rate is Become slow.

  However, in this embodiment, since the membrane is diffusion-bonded, the hydrogen permeable separation membrane 3 does not fill the pores of the porous metal 2 at the joint portion of the porous metal 2. Therefore, the amount of hydrogen permeable separation membrane 3 used can be reduced as compared with the prior art.

  Further, in the conventional method in which the hydrogen permeable separation membrane 3 is formed on the porous metal 2 and then rolled to form a thin film, if the hydrogen permeable separation membrane is formed by non-dense plating, there is a possibility of damage due to rolling. In order to avoid this problem, the hydrogen permeation separation membrane 3 must be formed very thick. Furthermore, even if it is formed thick, there is a possibility that it is partially peeled off at the joint portion with the porous metal 2.

  However, in the present embodiment, since the hydrogen permeable separation membrane 3 previously rolled is diffusion bonded to the porous metal 2, such a possibility can be reduced. Here, if necessary, the porous metal 2 may be rolled first.

  Further, the pores of the porous metal 2 may be deformed and the pores may be blocked or the shape may be changed. In this case, the hydrogen permeable separation membrane 3 part embedded in the part may be damaged. Although this is high, this embodiment can also reduce this point.

  In addition, when rolling after forming the hydrogen permeable separation membrane 3 on the porous metal 2, there is a possibility that a portion where the pores of the porous metal 2 are blocked by deformation during rolling may occur. The area of the portion where hydrogen is permeated and released from the permeation separation membrane 3 is reduced, which is actually smaller than the apparent hydrogen permeation area, and the hydrogen permeation amount may be reduced even under the same conditions. However, this can be reduced in the present embodiment.

  Furthermore, since it is laminated and has a multilayer structure, the strength is increased as compared with a single layer, and breakage can be suppressed. Further, the hydrogen permeable separation membrane 3 can be further thinned or the porous metal 2 serving as a support for maintaining the strength can be thinned, and the amount of the hydrogen permeable separation material 1 used can be reduced.

  In addition, since the number of layers inside the hydrogen permeable separation membrane 3 is increased to two or more, even if there are pinholes in two adjacent layers, at the junction between the two adjacent layers, Since there is little possibility that pinholes communicate with each other, the possibility that gases other than hydrogen pass through the hydrogen permeable separation membrane 3 can be reduced by pinholes penetrating the membrane.

  Furthermore, since Pd is more expensive than Ta and has a slower hydrogen diffusion rate, Pd is present only in the outermost layer of the multi-layered film like the Pd layer 8 and the Pd outer layer 10 and is used as a catalyst having hydrogen molecules as atoms. By doing so, the amount of Pd used can be reduced.

  Moreover, a high melting point transition metal having a body-centered cubic structure such as Ta absorbs hydrogen well because of its structure, so that the hydrogen permeation performance is high and the hydrogen permeation rate is high.

  Moreover, when this hydrogen permeation separator 1 is used for separating hydrogen gas from a mixed gas of hydrocarbon gas such as methane gas and water vapor to produce high-purity hydrogen gas, a high-temperature reaction at around 500 ° C. Since the porous metal 2 and the hydrogen permeable separation membrane 3 are disposed in the furnace, it is advantageous in terms of heat resistance to use Ta having a high melting point as a metal having high hydrogen permeability.

  Furthermore, the strength of the joint between the Pd layer 8 and the porous metal 2 of the hydrogen permeable separation membrane 3 where the joint area is smaller and the strength is lower than the joint area is improved, and the hydrogen permeable separation membrane 3 is made thinner. The amount used can be reduced, and damage can be suppressed.

  Further, since Ta has a higher tensile strength than Pd and has a good rolling property, when the hydrogen permeation separation membrane 3 is manufactured by rolling, it is easy to make it thin and the workability is improved.

  In addition, since diffusion bonding is performed in vacuum after removal of the oxide film, it is possible to prevent the oxide that hinders diffusion bonding, suppress the decrease in hydrogen permeation rate, and easily remove the oxide film that hinders diffusion bonding. Thus, the high-performance hydrogen permeation separator 1 can be manufactured relatively easily.

  In addition to the effects similar to the conventional one, the hydrogen permeation separator 1 having high performance, low material usage, high strength, and high reliability can be smoothly produced by the manufacturing method described in the present embodiment. Can be manufactured.

(Embodiment 2)
FIG. 2 is a cross-sectional view of the hydrogen permeation separator in Embodiment 2 of the present invention.

  In addition, about the same structure as Embodiment 1, the same code | symbol is attached | subjected and detailed description is abbreviate | omitted.

  The second embodiment is different from the first embodiment in that the hydrogen permeation separation material 1 is tubular for the purpose of disposing the same area in contact with the gas at a low volume, and the hydrogen permeation separation membrane 3 is formed on the inner surface of the tube. It is different in that is installed.

  In FIG. 2, the hydrogen permeation separation tube 14 a is formed by forming the hydrogen permeation separation material 1 into a tubular shape. A mixed gas flows in the tube 14 b, and hydrogen permeates from the inner surface 15 of the tube to the porous metal 2 through the hydrogen permeation separation membrane 3. And is discharged from the tube outer surface 16 to the tube outer tube 17. At this time, the inside 14 b is set to have a higher pressure than the outside 17.

  The operation and action of the hydrogen permeation separation tube 14a configured as described above will be described below.

  When the mixed gas containing hydrogen in the tube 14b is adsorbed on the tube inner surface 15, the hydrogen dissociates due to the material characteristics of the hydrogen permeable separation membrane 3 to become atoms and diffuses in the hydrogen permeable separation membrane 3 by diffusion toward the outside of the tube. Hydrogen atoms that permeate and permeate through the exposed surface portion of the hydrogen permeable separation membrane 3 that passes through a portion other than the joint portion of the porous metal 2, that is, through the communicating pores of the porous metal 2 to the outside of the tube 17, are hydrogen molecules, Hydrogen gas is released from the outer surface 16 to the outside 17 through the pores of the porous metal 2. In this way, only hydrogen permeates the hydrogen permeable separation membrane and separates high-concentration hydrogen from the mixed gas.

  From the above, even if the hydrogen permeable separation membrane 3 is broken, it may remain in the pores of the porous metal 2, and in this case, it can be suppressed from flowing out together with the permeated hydrogen. For example, in the case where permeated hydrogen is used as fuel for the fuel cell, it is possible to reduce problems caused by contamination of the fuel cell.

  Furthermore, since the inner surface 15 of the tube has a smaller area than the outer surface 16 of the tube, when the hydrogen permeable separation membrane 3 having the same film thickness is installed, by installing the hydrogen permeation separation membrane 3 on the tube 14 side, the same film thickness, The same hydrogen permeation performance can be maintained and the amount of hydrogen permeation separation membrane used can be reduced.

  As described above, the hydrogen permeation separator according to the present invention is excellent in heat resistance, pressure resistance, hydrogen permeation performance, and inexpensive, and can be used for separating hydrogen from a mixed gas to obtain high concentration hydrogen. Preferably, only high-concentration hydrogen is selected from high-temperature gas mixtures obtained by pyrolyzing and reforming organic solids such as biomass, plastics, coal, and other organic solids, sludge, petroleum, and waste oil. Can be separated and recovered and used as a hydrogen permeation separator for use as fuel.

Sectional drawing of the hydrogen permeable separation material in Embodiment 1 of this invention Sectional drawing of the hydrogen permeable separation material in Embodiment 2 of this invention

Explanation of symbols

1 Hydrogen Permeation Separation Material 2 Porous Metal 3 Hydrogen Permeation Separation Membrane 14b In Pipe

Claims (19)

  A hydrogen permeation separator in which a hydrogen permeation membrane that permeates hydrogen is diffusion bonded to at least one surface of a porous metal having pores that communicate with each other.   The hydrogen permeation separation material according to claim 1, wherein the hydrogen permeation separation membrane is a multi-layered membrane composed of a plurality of layers.   The hydrogen permeation separation membrane is a multilayer structure film comprising a plurality of laminated metal layers made of metal having a large amount of hydrogen storage, and Pd layers provided on both surfaces of the plurality of laminated metal layers. The hydrogen permeation separator described.   The hydrogen permeation separation material according to claim 2 or 3, wherein the hydrogen permeation separation membrane has a layer having a junction with a porous metal formed thicker than the other layers.   The hydrogen permeation separator according to claim 3 or 4, wherein the metal constituting the metal layer is a high melting point transition metal having a body-centered cubic structure.   The hydrogen permeation separator according to any one of claims 3 to 5, wherein a metal constituting the metal layer is Ta, Nb, or V.   The hydrogen permeation separator according to any one of claims 3 to 6, wherein each film of the multilayer structure film is diffusion bonded, and the multilayer structure film has a rolled structure.   The hydrogen permeation separation material according to any one of claims 1 to 7, wherein the hydrogen permeation separation material is installed so that hydrogen permeates from a surface opposite to a surface where the hydrogen permeation separation membrane is diffusion-bonded to the porous metal.   The hydrogen permeable separation material according to claim 8, wherein the hydrogen permeable separation membrane is located on the inner surface side of a tubular material made of a porous metal.   A method for producing a hydrogen permeable separation material, wherein a hydrogen permeable separation membrane that occludes or permeates hydrogen is diffusion bonded to at least one surface of a porous metal having pores that communicate with each other.   The method for producing a hydrogen permeable separation material according to claim 10, wherein a hydrogen permeable separation membrane produced by diffusion bonding and rolling a plurality of materials having hydrogen permeation performance is diffusion bonded to a porous metal.   The method for producing a hydrogen permeable separation material according to claim 10 or 11, wherein the diffusion bonding is performed after removing the oxide film on the surface on which diffusion bonding is performed.   The method for producing a hydrogen permeable separation material according to any one of claims 10 to 12, wherein diffusion bonding is performed in an atmosphere containing no oxygen or in a trace concentration.   The hydrogen permeable separation membrane is composed of two Pd foils and a plurality of metal foils made of a metal having high hydrogen permeation performance, and is stacked so that the plurality of metal foils are positioned between the two Pd foils. The method for producing a hydrogen permeation separation material according to any one of claims 10 to 13, wherein the laminated foils are rolled simultaneously with diffusion bonding or after diffusion bonding.   The method for producing a hydrogen permeable separator according to any one of claims 10 to 14, wherein the diffusion bonding is performed by laminating and hot pressing in vacuum.   The method for producing a hydrogen permeable separation material according to claim 14 or 15, wherein the thickness of the hydrogen permeable separation membrane is adjusted by adjusting the number of the metal foils to be overlapped.   The ratio of the thickness of the whole said metal layer laminated | stacked in the hydrogen permeable separation membrane and the thickness of the said Pd layer is adjusted by adjusting the number of sheets which the said metal foil overlaps. A method for producing a hydrogen permeation separator as described in 1.   18. The method for producing a hydrogen permeation separator according to claim 14, wherein the metal constituting the metal foil is a high melting point transition metal having a body-centered cubic structure.   The method for producing a hydrogen permeation separator according to claim 18, wherein the metal constituting the metal foil is Ta, Nb, or V.

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