JP4038292B2 - Hydrogen separator - Google Patents

Description

【００６８】
（考察：実施例１〜３、比較例）
実施例１〜３の水素分離体の断面構造を走査電子顕微鏡により観察したところ、Ｐｄ−Ａｇ合金膜中に多量のアルミナ粒子が分散されているとともに、Ｐｄ−Ａｇ合金とアルミナ粒子の密着性も良好であることが確認された。
また、実施例１〜３の水素分離体は、水素分離膜と多孔質基体との密着強度が十分であり、評価サイクル試験において４００回以上、連続評価試験において９０００時間以上という優れた耐久性を示し、更に、水素分離試験において精製された水素の純度は９９．９％以上であった。
一方、比較例の水素分離体は、評価サイクル試験及び連続評価試験において容易に水素分離膜の剥離を起こし、又、評価サイクル試験において、１５０回で気密性が低下した。
【００６９】
【発明の効果】
以上説明したように、本発明の水素分離体は、昇降温時に多孔質基体と水素分離膜との熱膨張差により発生する応力を緩和することにより、水素分離膜の亀裂や多孔質基体からの剥離を防止することができるため、水素分離効率および耐久性に優れている。
【図面の簡単な説明】
【図１】 本発明の水素分離体の一例を示す部分断面説明図である。
【図２】 本発明の分離体の他の例を示す部分断面説明図である。
【図３】 本発明の水素分離体を用いた水素精製方法についての説明図である。
【図４】 従来の水素分離体の一例を示す部分断面説明図である。
【符号の説明】
１…水素分離体、２…多孔質基体、２ａ…多孔質基体の表面、３…水素分離能を有する金属、４…水素分離膜、４ａ…水素分離膜の表面、５…小孔、６…無機材料粒子、７…第１層、７ａ…第１層の表面、８…第２層、１０…水素分離体、２０…真空チャンバー、２１…導入管（キャリアーガス）、２２…導入管（混合ガス）、２３…ｏリング、２４…水素分離体、２５…混合ガス（原料ガス）、２６…キャリヤーガス、２７…精製ガス、３０…水素分離構造体、３２…基材、３４…第１層、３６…第２層。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a hydrogen separator that diffuses and separates only hydrogen from a multicomponent mixed gas (raw material gas).
[0002]
[Prior art]
Conventionally, as a method of obtaining only a specific gas component from a multi-component mixed gas, a method of separating with an organic or inorganic gas separation membrane is known.
As separation membranes used in membrane separation methods, organic polymer membranes such as polyimide and polysulfone and inorganic compound membranes such as palladium or palladium alloy membranes are known as hydrogen separation membranes, and silver or silver alloy membranes are known as oxygen separation membranes. . In particular, the palladium or palladium alloy film has heat resistance and can obtain extremely high-purity hydrogen.
[0003]
Palladium or a palladium alloy has a property of allowing hydrogen to dissolve and permeate, and by utilizing this property, a thin film made of palladium or a palladium alloy is widely used as a hydrogen separator that separates hydrogen from a mixed gas containing hydrogen. ing.
However, since the mechanical strength of this palladium thin film alone is weak, Japanese Patent Application Laid-Open No. 62-273030 discloses that palladium on the surface of an inorganic porous support such as porous glass, porous ceramics, or porous aluminum oxide. Alternatively, a palladium alloy is applied to increase the mechanical strength of the thin film made of palladium or palladium alloy.
[0004]
JP-A-3-146122 discloses that a palladium thin film is formed on the surface of a heat-resistant porous substrate by an electroless plating method, a silver thin film is formed on the palladium thin film by an electroless plating method, and then heat treatment is performed. Discloses a method for producing a hydrogen separator. In this manufacturing method, a hydrogen separator having a porous substrate and a palladium alloy thin film covering the porous substrate is obtained. By this heat treatment, palladium and silver are uniformly distributed in the palladium alloy thin film. .
[0005]
Further, Japanese Patent Publication No. 5-53527 discloses that the surface of the porous ceramic layer is electrolessly plated with palladium to impart electrical conductivity, and then the surface is completely covered with electrolytic palladium plating. Disclosed is a method for producing a gas separation thin film for forming an electrolytic palladium or palladium alloy plating film.
Thereby, a denser palladium or palladium alloy thin film can be obtained even on a porous ceramic surface having a relatively large pore size.
[0006]
However, each of the hydrogen separators shown above contains, for example, a porous substrate and palladium when exposed to an atmosphere that fluctuates over a wide temperature range from low temperature (room temperature) to high temperature (300 to 500 ° C.). Due to the difference in thermal expansion coefficient from the hydrogen separation membrane, compressive stress is generated in the hydrogen separation membrane and tensile stress is generated in the hydrogen separation membrane at the time of temperature reduction. By repeating this operation, work hardening occurs and deformation becomes impossible. There was a problem that the film was cracked or peeled off from the porous substrate.
[0007]
In order to solve these problems, Japanese Patent Application Laid-Open No. 10-28850 discloses a substrate 32 made of porous ceramics, a first layer 34 formed on the substrate 32, and a first layer as shown in FIG. A hydrogen separation structure 30 is disclosed which is formed by laminating a second layer 36 formed on the layer 34 and made of palladium or an alloy containing palladium.
This is because the first layer 34 is formed of a material having a coefficient of thermal expansion between the base material 32 and the second layer 36, so that the heat of the base material 32 and the second layer 36 can be obtained in an atmosphere with a large temperature fluctuation. The stress generated by the difference in expansion is alleviated to prevent the second layer 36 from being peeled off from the base material 32.
[0008]
However, since the first layer 34 does not contain palladium, the first layer 34 becomes an inhibition layer from the viewpoint of hydrogen permeation, and the first layer 34 is a porous film (a film formed so as to fill part of the holes on the surface of the substrate). However, a decrease in hydrogen separation efficiency due to a decrease in hydrogen permeation rate is inevitable.
In addition, when the first layer 34 is made more porous to prevent a decrease in the hydrogen permeation rate, the second layer 36 cannot fill the holes on the surface of the base material, and pinholes are generated. Since the airtightness of the two layers 36 cannot be maintained, there is a problem that high purity hydrogen cannot be obtained.
[0009]
[Problems to be solved by the invention]
The present invention has been made in view of the above-described conventional problems, and the object of the present invention is to relieve the stress generated due to the difference in thermal expansion between the porous substrate and the hydrogen separation membrane when the temperature is raised and lowered. An object of the present invention is to provide a hydrogen separator excellent in hydrogen separation efficiency and durability, which can prevent cracking of the hydrogen separation membrane and peeling from a porous substrate.
[0010]
[Means for Solving the Problems]
According to the present invention, a hydrogen separator in which a hydrogen separation membrane is formed on a porous substrate, wherein the hydrogen separation membrane is obtained by dispersing inorganic material particles in a metal having hydrogen separation ability. The thermal expansion coefficient of the inorganic material particles is a value between the porous substrate and the metal having hydrogen separation ability. In addition, the hydrogen separation membrane is dispersed in a stepwise or continuously inclined manner in the metal having hydrogen separation ability from the surface of the porous substrate to the surface of the hydrogen separation membrane. A hydrogen separator is provided.
[0011]
At this time, in the present invention, , The content of inorganic material particles in the hydrogen separation membrane is preferably 5 to 40% by volume.
[0012]
According to the present invention, there is also provided a hydrogen separator in which a hydrogen separation membrane is formed on a porous substrate, wherein the hydrogen separation membrane is obtained by dispersing inorganic material particles in a metal having hydrogen separation ability. In addition, inorganic material particles Coefficient of thermal expansion But , A first layer having a value between a porous substrate and a metal having a hydrogen separation ability, and a second layer made of a metal having a hydrogen separation ability and stacked on the first layer. A hydrogen separator is provided.
[0013]
At this time, in the present invention, the first layer is dispersed from the surface of the porous substrate toward the surface of the first layer, and the inorganic material particles are dispersed stepwise or continuously in a metal having hydrogen separation ability. The content of the inorganic material particles in the first layer is preferably 5 to 40% by volume.
[0014]
In the present invention, the average particle diameter of the inorganic material particles is preferably 0.1 to 5 μm, and the main component of the inorganic material particles is SiO 2 ₂ , Al ₂ O _Three , ZrO ₂ TiO ₂ , Cr ₂ O _Three It is preferable that it is either.
[0015]
Further, the metal having hydrogen separation ability is preferably palladium, an alloy containing palladium as a main component, or an alloy containing palladium.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
In the hydrogen separator of the present invention, a hydrogen separation membrane formed on a porous substrate is obtained by dispersing inorganic material particles in a metal having hydrogen separation ability. It consists of a first layer having a value between a metal having separability and a second layer made of a metal having a hydrogen separability laminated on the first layer.
Note that the hydrogen separation membrane may be only the first layer.
[0017]
As a result, the stress generated by the difference in thermal expansion between the porous substrate and the hydrogen separation membrane during the temperature rise and fall can be reduced, so that the hydrogen separation membrane can be prevented from cracking and peeling from the porous substrate. A hydrogen separator excellent in separation efficiency and durability can be obtained.
[0018]
Hereinafter, the present invention will be described in more detail with reference to the drawings.
FIG. 1 is a partial cross-sectional explanatory view showing an example of the hydrogen separator of the present invention.
An example of the hydrogen separator of the present invention is obtained by forming a hydrogen separation membrane 4 in which inorganic material particles 6 are dispersed in a metal 3 having hydrogen separation ability on a porous substrate 2 as shown in FIG. It is.
The hydrogen separator 1 can reduce the yield stress of the hydrogen separation membrane 4 by making the thermal expansion coefficient of the hydrogen separation membrane 4 close to the thermal expansion coefficient of the porous substrate 2, so Since the stress generated in 4 can be relaxed, cracks in the hydrogen separation membrane 4 and peeling from the porous substrate can be prevented.
Thereby, the durability and reliability of the hydrogen separator 1 can be greatly improved.
[0019]
In order to realize the above, the thermal expansion coefficient of the inorganic material particles 6 is a value between the porous substrate 2 and the metal 3 having hydrogen separation ability, more preferably, the porous substrate 2 and the hydrogen separation ability. It is important that the value is intermediate to that of the metal 3 possessed.
This macroscopically complements the difference in thermal expansion between the hydrogen separation membrane 4 and the porous substrate 2 by dispersing the inorganic material particles 6 satisfying the above conditions in the metal 3 having hydrogen separation ability. This is because the stress generated by the difference in thermal expansion between the porous substrate 2 and the hydrogen separation membrane 4 at the time of temperature rise and fall can be relaxed.
[0020]
Further, the hydrogen separation membrane 4 was dispersed in a stepwise or continuous manner in an inorganic material particle 6 in the metal 3 having hydrogen separation ability from the surface 2a of the porous substrate toward the surface 4a of the hydrogen separation membrane. To be things is important .
This is because the content of the inorganic material particles 6 in the vicinity of the surface 2a of the porous substrate is relatively higher than that in the vicinity of the surface 4a of the hydrogen separation membrane, so that the porous substrate 2 and the hydrogen separation membrane 4 This is because the stress generated by the difference in thermal expansion is further relaxed, so that the effect of preventing cracks in the hydrogen separation membrane 4 and peeling from the porous substrate 2 can be further improved.
[0021]
Furthermore, the content of the inorganic material particles in the hydrogen separation membrane 4 is preferably 5 to 40% by volume.
This relieves the stress generated by the difference in thermal expansion between the porous substrate 2 and the hydrogen separation membrane 4 when the temperature rises and falls when the content of the inorganic material particles 6 in the hydrogen separation membrane 4 is less than 5% by volume. Because you can't.
On the other hand, when the content of the inorganic material particles 6 in the hydrogen separation membrane 4 exceeds 40% by volume, the inorganic material particles 6 inhibit hydrogen diffusion, and thus the hydrogen permeation rate is reduced.
[0022]
Note that the thickness b of the hydrogen separation membrane 4 is preferably 50 μm or less.
This is because, if the thickness b of the hydrogen separation membrane 4 exceeds 50 μm, it takes time for hydrogen to diffuse in the hydrogen separation membrane 4 during the hydrogen separation by the hydrogen separator 1, and therefore the hydrogen separation time. This is because it takes a long time and the hydrogen separation efficiency decreases.
[0023]
Next, another example of the hydrogen separator of the present invention will be described.
As shown in FIG. 2, another example of the hydrogen separator of the present invention includes a first layer 7 in which inorganic material particles 6 are dispersed in a metal 3 having hydrogen separation capability on a porous substrate 2, and a first layer 7. The hydrogen separation membrane 4 is formed on the first layer 4 and the second separation layer 8 made of the metal 3 having hydrogen separation ability.
[0024]
The hydrogen separator 10 described above has the first layer 7 that is close to the thermal expansion coefficient of the porous substrate 2 as a buffer layer between the porous substrate 2 and the second layer 8, so Since the stress generated in the two layers 8 can be relaxed, cracks in the hydrogen separation membrane 4 and peeling from the porous substrate 2 can be prevented.
Thereby, the durability and reliability of the hydrogen separator 10 can be significantly improved.
Further, the hydrogen separator 10 described above can minimize the content of the inorganic material particles 6 that inhibit hydrogen diffusion as compared with the case where only the first layer 7 is used (see FIG. 1). Therefore, the hydrogen permeation rate of the hydrogen separation membrane 4 can be further improved. Further, since the first layer is obtained by dispersing the inorganic material particles 6 in the metal 3 having hydrogen separation ability, the first layer has good compatibility with the metal 3 having hydrogen separation ability which is the second layer 8.
[0025]
In order to realize the above, the thermal expansion coefficient of the inorganic material particles 6 is a value between the porous substrate 2 and the metal 3 having hydrogen separation ability, more preferably, the porous substrate 2 and the hydrogen separation ability. It is important that the value is intermediate to that of the metal 3 possessed.
This macroscopically complements the difference in thermal expansion between the first layer 7 and the porous substrate 2 by dispersing the inorganic material particles 6 satisfying the above conditions in the metal 3 having hydrogen separation ability. This is because the stress generated by the difference in thermal expansion between the porous substrate 2 and the first layer 7 at the time of temperature rise and fall can be relaxed.
[0026]
Further, the first layer 7 has the inorganic material particles 6 dispersed in a stepwise or continuous manner in the metal 3 having hydrogen separation ability from the surface 2a of the porous substrate toward the surface 7a of the first layer. It is preferable.
This is because the content of the inorganic material particles 6 in the vicinity of the surface 2a of the porous substrate is relatively higher than that in the vicinity of the surface 7a of the first layer, so that the porous substrate 2 and the first layer 7 This is because the stress generated by the difference in thermal expansion can be further relaxed, and the effect of preventing cracks in the first layer 7 and peeling from the porous substrate can be further improved.
[0027]
Furthermore, the content of the inorganic material particles 6 in the first layer 7 is preferably 5 to 40% by volume.
When the content of the inorganic material particles 6 in the first layer 7 is less than 5% by volume, the stress generated due to the difference in thermal expansion between the porous substrate 2 and the first layer 7 during temperature rise and fall is alleviated. Because you can't.
On the other hand, when the content rate of the inorganic material particles 6 in the first layer exceeds 40% by volume, the inorganic material particles 6 inhibit hydrogen diffusion, so that the hydrogen permeation rate is reduced.
[0028]
The thickness (c + d) of the hydrogen separation membrane 4 is preferably 50 μm or less.
This is because if the thickness (c + d) of the hydrogen separation membrane 4 exceeds 50 μm, it takes time for hydrogen to diffuse in the hydrogen separation membrane 4 during the hydrogen separation by the hydrogen separator 1. This is because the time is prolonged and the hydrogen separation efficiency is lowered.
Further, in order to improve the hydrogen separation efficiency of the hydrogen separation membrane 4 while relaxing the stress generated due to the difference in thermal expansion between the porous substrate 2 and the second layer 8 when the temperature is raised and lowered, the thickness ratio of the hydrogen separation membrane 4 The thickness c of the first layer 7 is preferably 20 to 50%, and the thickness d of the second layer 8 is preferably 50 to 80%.
[0029]
Here, in the hydrogen separators 1 and 10 of the present invention, as shown in FIGS. 1 and 2, a part of the metal 3 having hydrogen separation ability in the hydrogen separation membrane 4 covers the surface 2 a of the porous substrate. It is preferable that the metal 3 having a hydrogen separation ability that fills and closes the inside of the small holes 5 opened on the surface 2 a of the porous substrate is continuous with the hydrogen separation membrane 4.
As a result, the adhesion between the hydrogen separation membrane 4 and the porous substrate 2 is improved, and the hydrogen separation membrane 4 is difficult to peel from the porous substrate surface 2a.
[0030]
Further, the depth a in which the metal 3 having hydrogen separation ability penetrates into the porous substrate 2 is preferably 1 to 30 μm, more preferably 1 to 20 μm from the surface 2 a of the porous substrate. Preferably, it is still more preferable that it is 1-10 micrometers.
This is because if the depth is smaller than 1 μm, the small holes are not sufficiently blocked by the metal 3 having hydrogen separation ability, the raw material gas may leak to the purified gas side, and the hydrogen separation membrane 4 is porous. It is because it becomes easy to peel from the surface 2a of the porous substrate.
On the other hand, if this depth is larger than 30 μm, it takes time for hydrogen to diffuse through the metal 3 having hydrogen separation ability during the hydrogen separation by the hydrogen separator 1, so that the hydrogen separation time becomes long, This is because the hydrogen separation efficiency is lowered.
Further, when the porous substrate 2 has a tube shape, the surface 2a of the porous substrate in which the metal 3 having hydrogen separation ability is filled in the small holes may be outside or inside the porous substrate having the tube shape. .
[0031]
The average particle diameter of the inorganic material particles 6 used in the present invention is preferably 0.1 to 5 μm.
This is because when the average particle diameter of the inorganic material particles is less than 0.1 μm, the inorganic material particles aggregate together, and the inorganic material particles segregate inappropriately in the hydrogen separation membrane.
On the other hand, when the average particle diameter of the inorganic material particles exceeds 5 μm, not only is it difficult to obtain the airtightness of the hydrogen separation membrane, but also the inorganic material particles in the plating solution are difficult to disperse. This is because it becomes difficult to control the content ratio of the.
[0032]
Moreover, it is preferable that the shape of the inorganic material particle 6 used by this invention is a spherical form.
This can disperse the stress generated at the interface between the metal having the ability to separate hydrogen and the inorganic material particles when the temperature is raised and lowered, so that cracking of the hydrogen separation membrane can be prevented.
[0033]
Further, the main component of the inorganic material particles 6 used in the present invention is a value between the porous substrate and the metal having hydrogen separating ability, and more preferably an intermediate value between the porous substrate and the metal having hydrogen separating ability. As long as it has a coefficient of thermal expansion of ₂ , Al ₂ O _Three , ZrO ₂ TiO ₂ , Cr ₂ O _Three It is preferable that it is either.
[0034]
The porous substrate 2 used in the present invention is preferably one that does not react with the raw material gas. Specifically, alumina, silica, silica-alumina, mullite, cordierite, zirconia, carbon and porous glass are used. Etc. can be used.
[0035]
The porous substrate described above has a large number of fine pores that are three-dimensionally continuous, and the average pore diameter of the porous substrate is preferably 0.1 to 3.0 μm.
This is because when the average pore diameter is less than 0.1 μm, the anchor effect between the porous substrate and the hydrogen separation membrane is small, so when used for a long time, the difference in expansion between the porous substrate and the hydrogen separation membrane due to temperature change or This is because the hydrogen separation membrane is peeled off from the porous substrate due to expansion / contraction of the hydrogen separation membrane due to gas occlusion / release.
On the other hand, when the average pore diameter exceeds 3.0 μm, small holes cannot be closed by electroless plating, and airtightness cannot be ensured, so that high-purity hydrogen cannot be obtained.
That is, the hydrogen separator of the present invention can suppress peeling of the hydrogen separation membrane from the porous substrate by limiting the average pore diameter of the small pores of the porous substrate to the above-mentioned size.
Such a porous substrate can be obtained, for example, by the method described in JP-A-62-273030.
[0036]
Further, it is preferable that the pores of the porous substrate 2 used in the present invention have the same pore diameter.
This makes it easy to adjust the depth of the solution that penetrates into the porous substrate in the activation process, the electroless composite plating process, and the electroless plating process. This is because it is easy to maintain a uniform depth of penetration into the inside.
In addition, the thickness of the porous substrate 2 is not particularly limited as long as it can maintain a sufficient mechanical strength in the use environment.
[0037]
Furthermore, the porosity of the porous substrate 2 used in the present invention is preferably 25 to 45%.
This is because if the porosity of the porous substrate 2 is smaller than 25%, the hydrogen diffusibility is poor, and if it is larger than 45%, the mechanical strength is lowered.
In order to satisfy the above conditions, the size of the particles constituting the porous substrate 2 is preferably 1.5 to 6.0 times the average pore diameter of the porous substrate 2, and is preferably 2.0 to 4 More preferably, it is 0.0 times.
[0038]
The shape of the porous substrate 2 is preferably a surface. The surface includes a flat surface and a curved surface, and naturally includes a tube shape corresponding to a shape in which the curved surface is closed.
When the porous substrate has a tube shape, the shape of the tube cross section is arbitrary, but a circular substrate is preferable because it is easily available.
Moreover, the shape of the porous substrate 2 may be a plate shape, and can be an arbitrary shape depending on the purpose of use.
[0039]
The metal 3 having hydrogen separation ability used in the present invention is preferably palladium, an alloy containing palladium as a main component, or an alloy containing palladium.
In addition, when the metal 3 having hydrogen separation ability is made of a palladium alloy, Japanese Membrane Science, 56 (1991) 315-325: “Hydrogen Permeable Palladium-Silver Alloy Membrane Supported on Porous Ceramics” and Japanese Patent Laid-Open No. 63-29540. As described in the publication, the content of metals other than palladium is preferably 10 to 30% by weight.
The main purpose of alloying palladium is to prevent hydrogen embrittlement of palladium and improve the separation efficiency at high temperatures.
Moreover, it is preferable to contain silver as a metal other than palladium in order to prevent hydrogen embrittlement of palladium.
[0040]
Next, the hydrogen separator of the present invention is produced, for example, by performing an activation process as shown below, and then appropriately selecting an electroless composite plating process and an electroless plating process.
At this time, by using a film formation method by electroless plating, it is possible to form a film even if the porous substrate has a complicated shape as compared with other film formation methods. It is also possible to suitably form a film on the inner surface of the tube.
[0041]
In the activation step, one side of the porous substrate is immersed in a solution containing an activated metal so that the pressure applied to the one side is greater than the pressure on the other side of the porous substrate, whereby the porous substrate is porous. The solution is allowed to enter the inside of a small hole opened in the surface on one side where the pressure of the substrate is larger.
Due to such a pressure difference, the activated metal adheres to the surface of the porous substrate, and the activated metal also adheres to the surface inside the small holes opened on the surface of the porous substrate.
A dispersion plating film is formed on the surface to which the activated metal has adhered in the following electroless composite plating process.
In this activation step, if one side to which a larger pressure is applied is immersed in the solution, the opposite one side does not need to be immersed in the solution.
For example, a tube-shaped porous substrate can be used, the outside thereof can be immersed in a solution containing an activated metal, and the inside of the tube can be drawn with a vacuum pump. Alternatively, a tubular porous substrate may be used, and the outside thereof may be immersed in a solution containing an activated metal, pressure may be applied to the solution, and the inside of the tube may be maintained at a constant pressure.
In any case, the pressure can be changed by immersing the solution inside the tube by reversing the outside and inside of the tube.
[0042]
As the activated metal, a compound containing a palladium divalent ion can be suitably used. Specifically, the activation step can be performed by alternately immersing the porous substrate in an aqueous hydrochloric acid solution of palladium chloride and an aqueous hydrochloric acid solution of tin chloride, and even when immersed in any of these solutions. It is preferable to maintain a predetermined pressure difference.
[0043]
In the electroless composite plating step, inorganic material particles having a predetermined average particle diameter in an aqueous solution containing a palladium salt or silver salt, a complexing agent, a reducing agent, and the like are adjusted so that the particle concentration in the plating solution is 5 to 100 g / l. By immersing the surface of the activated porous substrate in the plating solution dispersed in, a dispersed plating film (plating film in which inorganic material particles are co-deposited on palladium or silver) is formed on the surface of the porous substrate. To do.
In order to prevent aggregation and precipitation of inorganic material particles in the plating solution, it is preferable to continuously perform bath agitation.
The reason for limiting the particle concentration in the plating solution as described above is to optimize the content of inorganic material particles in the dispersion plating film on the surface of the porous substrate (5 to 40% by volume).
[0044]
Even in this electroless composite plating process, by the same method as the activation process, the pressure applied to one side of the activated porous substrate is larger than the pressure on the other side of the porous substrate. It is preferable to immerse in the plating solution.
This pressure difference makes it easy to allow the plating solution to enter the small holes opened on the surface of the porous substrate.
[0045]
In addition, the depth of penetration of palladium from the surface of the porous substrate can be adjusted by adjusting the immersion time, the temperature of the plating solution, the pressure difference between both surfaces of the porous substrate, etc. in the electroless composite plating process. .
[0046]
Further, when the inorganic material particles are dispersed in a stepwise or continuous manner in the dispersion plating film, the dispersion plating film having a different content of the inorganic material particles in the dispersion plating film is porous stepwise or continuously. It can be realized by forming it on the surface of the substrate.
[0047]
The electroless plating process is performed by immersing the surface of the dispersion plating film formed on the surface of the porous substrate in a plating solution containing a silver salt, a complexing agent, a reducing agent, etc. Is formed.
[0048]
Even in this electroless plating process, in the same manner as in the activation process, the pressure applied to one side of the activated porous substrate is larger than the pressure on the other side of the porous substrate. It is preferable to immerse in a plating solution.
This pressure difference makes it easy to allow the plating solution to enter the small holes opened on the surface of the porous substrate.
[0049]
Here, when producing the hydrogen separator of the present invention, after forming a palladium composite layer as a dispersion plating film on the surface of the porous substrate, a silver composite layer or a plating film as a dispersion plating film is further formed on the surface. It is preferable to form a silver layer, and then perform a heat treatment to interdiffuse palladium and silver, thereby alloying palladium and silver.
[0050]
【Example】
EXAMPLES Hereinafter, although it demonstrates still in detail based on an Example, this invention is not limited to these Examples.
[0051]
Example 1
First, the porous substrate was activated. A porous α-alumina tube having a cylindrical shape with an outer diameter of 17 mm, an inner diameter of 13 mm, and a length of 1000 mm and an average pore diameter of 0.5 μm was used as the porous substrate. The outer surface of this alumina tube is SnCl ₂ ・ 2H ₂ It was immersed in a 0.1% hydrochloric acid aqueous solution containing 0.1% by weight of O for 1 minute. The outer surface of the tube is then ₂ Was immersed in a 0.1% aqueous hydrochloric acid solution containing 0.01% by weight for 1 minute. This immersion treatment was repeated with both aqueous hydrochloric acid solutions so that each aqueous hydrochloric acid solution was immersed 10 times.
[0052]
Next, a Pd composite layer was formed on the outer surface of the alumina tube by electroless composite plating. In 1 l of water from which ions have been removed, [Pd (NH _Three ) _Four ] Cl ₂ ・ H ₂ O (5.4 g), 2Na · EDTA (67.2 g), ammonia water having an ammonia concentration of 28% (651.3 ml), H ₂ NNH ₂ ・ H ₂ Alumina particles having an average particle diameter of 0.2 μm were dispersed in an aqueous solution to which O (0.46 ml) was added so as to have a concentration of 10 g / l to obtain a composite plating bath. During plating, the bath was continuously stirred to prevent the aggregation and precipitation of alumina particles. The outer surface of the porous alumina tube subjected to the activation treatment was immersed in this aqueous solution whose temperature was controlled at 50 ° C. for 180 minutes.
[0053]
Further, an Ag composite layer was formed on the outer surface of the alumina tube on which the Pd composite layer was formed by electroless composite plating. In 1 l of water from which ions have been removed, [Pd (NH _Three ) _Four ] Cl ₂ ・ H ₂ O (0.54g), AgNO _Three (4.86 g), 2Na · EDTA (33.6 g), ammonia water with an ammonia concentration of 28% (651.3 ml), H ₂ NNH ₂ ・ H ₂ Alumina particles having an average particle diameter of 0.2 μm were dispersed in an aqueous solution to which O (0.46 ml) was added so as to have a concentration of 10 g / l to obtain a composite plating bath. During plating, the bath was continuously stirred to prevent the aggregation and precipitation of alumina particles. The outer surface of the alumina tube on which the Pd composite layer was formed was immersed in this aqueous solution controlled at 50 ° C. for 60 minutes.
Finally, it was kept at 1000 ° C. for 10 hours, and was subjected to heat treatment, whereby palladium and silver were interdiffused, and palladium and silver were alloyed to obtain a hydrogen separator.
[0054]
(Example 2)
First, the porous substrate was activated. A porous α-alumina tube having a cylindrical shape with an outer diameter of 17 mm, an inner diameter of 13 mm, and a length of 1000 mm and an average pore diameter of 0.5 μm was used as the porous substrate. The outer surface of this alumina tube is SnCl ₂ ・ 2H ₂ It was immersed in a 0.1% hydrochloric acid aqueous solution containing 0.1% by weight of O for 1 minute. The outer surface of the tube is then ₂ Was immersed in a 0.1% aqueous hydrochloric acid solution containing 0.01% by weight for 1 minute. This immersion treatment was repeated with both aqueous hydrochloric acid solutions so that each aqueous hydrochloric acid solution was immersed 10 times.
[0055]
Next, a Pd composite layer was formed on the outer surface of the alumina tube by electroless composite plating. In 1 l of water from which ions have been removed, [Pd (NH _Three ) _Four ] Cl ₂ ・ H ₂ O (5.4 g), 2Na · EDTA (67.2 g), ammonia water having an ammonia concentration of 28% (651.3 ml), H ₂ NNH ₂ ・ H ₂ Alumina particles having an average particle diameter of 0.2 μm were dispersed in an aqueous solution to which O (0.46 ml) was added so as to have a concentration of 10 g / l to obtain a composite plating bath. During plating, the bath was continuously stirred to prevent the aggregation and precipitation of alumina particles. The outer surface of the porous alumina tube subjected to the activation treatment was immersed in this aqueous solution whose temperature was controlled at 50 ° C. for 180 minutes.
[0056]
Furthermore, an Ag layer was formed on the outer surface of the alumina tube on which the Pd composite layer was formed by electroless plating. In 1 l of water from which ions have been removed, [Pd (NH _Three ) _Four ] Cl ₂ ・ H ₂ O (0.54g), AgNO _Three (4.86 g), 2Na · EDTA (33.6 g), ammonia water with an ammonia concentration of 28% (651.3 ml), H ₂ NNH ₂ ・ H ₂ An aqueous solution to which O (0.46 ml) was added was prepared, and the outer surface of the alumina tube on which the Pd composite layer was formed was immersed in this aqueous solution whose temperature was controlled at 50 ° C. for 60 minutes.
Finally, it was kept at 1000 ° C. for 10 hours, and was subjected to heat treatment, whereby palladium and silver were interdiffused, and palladium and silver were alloyed to obtain a hydrogen separator.
[0057]
(Example 3)
First, the porous substrate was activated. A porous α-alumina tube having a cylindrical shape with an outer diameter of 17 mm, an inner diameter of 13 mm, and a length of 1000 mm and an average pore diameter of 0.5 μm was used as the porous substrate. The outer surface of this alumina tube is SnCl ₂ ・ 2H ₂ It was immersed in a 0.1% hydrochloric acid aqueous solution containing 0.1% by weight of O for 1 minute. The outer surface of the tube is then ₂ Was immersed in a 0.1% aqueous hydrochloric acid solution containing 0.01% by weight for 1 minute. This immersion treatment was repeated with both aqueous hydrochloric acid solutions so that each aqueous hydrochloric acid solution was immersed 10 times.
[0058]
Next, the Pd composite layer 1 was formed on the outer surface of the alumina tube by electroless composite plating. In 1 l of water from which ions have been removed, [Pd (NH _Three ) _Four ] Cl ₂ ・ H ₂ O (5.4 g), 2Na · EDTA (67.2 g), ammonia water having an ammonia concentration of 28% (651.3 ml), H ₂ NNH ₂ ・ H ₂ Alumina particles having an average particle diameter of 0.2 μm were dispersed in an aqueous solution to which O (0.46 ml) was added so as to have a concentration of 20 g / l to obtain a composite plating bath. During plating, the bath was continuously stirred to prevent the aggregation and precipitation of alumina particles. The outer surface of the porous alumina tube subjected to the activation treatment was immersed in this aqueous solution whose temperature was controlled at 50 ° C. for 90 minutes.
[0059]
Next, the Pd composite layer 2 was formed on the outer surface of the alumina tube on which the Pd composite layer 1 was formed by electroless composite plating. In 1 l of water from which ions have been removed, [Pd (NH _Three ) _Four ] Cl ₂ ・ H ₂ O (5.4 g), 2Na · EDTA (67.2 g), ammonia water having an ammonia concentration of 28% (651.3 ml), H ₂ NNH ₂ ・ H ₂ Alumina particles having an average particle diameter of 0.2 μm were dispersed in an aqueous solution to which O (0.46 ml) was added so as to have a concentration of 10 g / l to obtain a composite plating bath. During plating, the bath was continuously stirred to prevent the aggregation and precipitation of alumina particles. The outer surface of the alumina tube on which the Pd composite layer 1 was formed was immersed for 90 minutes in this aqueous solution whose temperature was controlled at 50 ° C.
[0060]
Further, an Ag layer was formed on the outer surface of the alumina tube on which the Pd composite layer 2 was formed by electroless plating. In 1 l of water from which ions have been removed, [Pd (NH _Three ) _Four ] Cl ₂ ・ H ₂ O (0.54g), AgNO _Three (4.86 g), 2Na · EDTA (33.6 g), ammonia water with an ammonia concentration of 28% (651.3 ml), H ₂ NNH ₂ ・ H ₂ An aqueous solution to which O (0.46 ml) was added was prepared, and the outer surface of the alumina tube on which the Pd composite layer 2 was formed was immersed in this aqueous solution whose temperature was controlled at 50 ° C. for 60 minutes.
Finally, it was kept at 1000 ° C. for 10 hours, and was subjected to heat treatment, whereby palladium and silver were interdiffused, and palladium and silver were alloyed to obtain a hydrogen separator.
[0061]
(Comparative example)
First, the porous substrate was activated. A porous α-alumina tube having a cylindrical shape with an outer diameter of 17 mm, an inner diameter of 13 mm, and a length of 1000 mm and an average pore diameter of 0.5 μm was used as the porous substrate. The outer surface of this alumina tube is SnCl ₂ ・ 2H ₂ It was immersed in a 0.1% hydrochloric acid aqueous solution containing 0.1% by weight of O for 1 minute. The outer surface of the tube is then ₂ Was immersed in a 0.1% aqueous hydrochloric acid solution containing 0.01% by weight for 1 minute. This immersion treatment was repeated with both aqueous hydrochloric acid solutions so that each aqueous hydrochloric acid solution was immersed 10 times.
[0062]
Next, a Pd layer was formed on the outer surface of the alumina tube after the activation treatment by electroless plating. In 1 l of water from which ions have been removed, [Pd (NH _Three ) _Four ] Cl ₂ ・ H ₂ O (5.4 g), 2Na · EDTA (67.2 g), ammonia water having an ammonia concentration of 28% (651.3 ml), H ₂ NNH ₂ ・ H ₂ An aqueous solution to which O (0.46 ml) was added was prepared, and the outer surface of the alumina tube was immersed in this aqueous solution whose temperature was controlled at 50 ° C. for 180 minutes.
[0063]
Further, an Ag layer was formed on the outer surface of the alumina tube on which the Pd layer was formed by electroless plating. In 1 l of water from which ions have been removed, [Pd (NH _Three ) _Four ] Cl ₂ ・ H ₂ O (0.54g), AgNO _Three (4.86 g), 2Na · EDTA (33.6 g), ammonia water with an ammonia concentration of 28% (651.3 ml), H ₂ NNH ₂ ・ H ₂ An aqueous solution to which O (0.46 ml) was added was prepared, and the outer surface of the alumina tube on which the Pd layer was formed was immersed in this aqueous solution whose temperature was controlled at 50 ° C. for 60 minutes.
Finally, it was kept at 1000 ° C. for 10 hours, and was subjected to heat treatment, whereby palladium and silver were interdiffused, and palladium and silver were alloyed to obtain a hydrogen separator.
[0064]
The hydrogen separator thus obtained (Examples 1 to 3, Comparative Example) was subjected to an airtight test. Argon gas was introduced to the outside of the alumina tube, and 9 kgf / cm ² The amount of gas leaking into the alumina tube was measured.
[0065]
Moreover, about each obtained hydrogen separator (Examples 1-3, a comparative example), the hydrogen separation test was done using the apparatus shown in FIG.
At this time, a mixed gas composed of 75 volume% hydrogen and 25 volume% carbon dioxide was used as the source gas.
First, the chamber 20 was heated to 500 ° C. Next, on the outside of the hydrogen separator 24, the pressure is 9 kgf / cm. ² The above mixed gas 25 was introduced at 5 N liters per minute (that is, the volume at room temperature was 5 liters).
The pressure is 1 kgf / cm inside the hydrogen separator 24. ² Of 0.1 N liters per minute was introduced as a carrier gas 26.
Next, the purified gas 27 thus obtained was quantitatively analyzed by gas chromatography, and the gas permeation rate of the purified gas 27 and the hydrogen concentration in the purified gas 27 were examined.
[0066]
Next, for each of the obtained hydrogen separators (Examples 1 to 3, Comparative Example), an evaluation cycle test and a continuous evaluation test were performed to examine the durability of the hydrogen separator.
In the evaluation cycle test, the hydrogen separator was heated in Ar gas from room temperature to 500 ° C., exposed to a mixed gas at 500 ° C., and cooled in Ar gas from 500 ° C. to room temperature. This was done by examining the number of steps required to decrease.
The continuous evaluation test was performed by exposing the hydrogen separator to a mixed gas at a temperature of 500 ° C. and examining the time required until the airtightness was lowered.
These test results are shown in Table 1.
[0067]
[Table 1]

[0068]
(Discussion: Examples 1 to 3, Comparative Example)
When the cross-sectional structures of the hydrogen separators of Examples 1 to 3 were observed with a scanning electron microscope, a large amount of alumina particles were dispersed in the Pd—Ag alloy film, and the adhesion between the Pd—Ag alloy and the alumina particles was also high. It was confirmed to be good.
The hydrogen separators of Examples 1 to 3 have sufficient adhesion strength between the hydrogen separation membrane and the porous substrate, and have excellent durability of 400 times or more in the evaluation cycle test and 9000 hours or more in the continuous evaluation test. Furthermore, the purity of the hydrogen purified in the hydrogen separation test was 99.9% or more.
On the other hand, the hydrogen separator of the comparative example easily peeled off the hydrogen separation membrane in the evaluation cycle test and the continuous evaluation test, and the hermeticity decreased after 150 times in the evaluation cycle test.
[0069]
【The invention's effect】
As described above, the hydrogen separator of the present invention relaxes the stress generated by the thermal expansion difference between the porous substrate and the hydrogen separation membrane when the temperature is raised and lowered, thereby preventing the hydrogen separation membrane from cracking or from the porous substrate. Since peeling can be prevented, hydrogen separation efficiency and durability are excellent.
[Brief description of the drawings]
FIG. 1 is a partial cross-sectional explanatory view showing an example of a hydrogen separator according to the present invention.
FIG. 2 is a partial cross-sectional explanatory view showing another example of the separator of the present invention.
FIG. 3 is an explanatory diagram of a hydrogen purification method using the hydrogen separator of the present invention.
FIG. 4 is a partial cross-sectional explanatory view showing an example of a conventional hydrogen separator.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Hydrogen separator, 2 ... Porous substrate, 2a ... Surface of porous substrate, 3 ... Metal which has hydrogen separation ability, 4 ... Hydrogen separation membrane, 4a ... Surface of hydrogen separation membrane, 5 ... Small hole, 6 ... Inorganic material particles, 7 ... first layer, 7a ... surface of first layer, 8 ... second layer, 10 ... hydrogen separator, 20 ... vacuum chamber, 21 ... introduction tube (carrier gas), 22 ... introduction tube (mixing) Gas), 23 ... o-ring, 24 ... hydrogen separator, 25 ... mixed gas (source gas), 26 ... carrier gas, 27 ... purified gas, 30 ... hydrogen separation structure, 32 ... substrate, 34 ... first layer 36 ... Second layer.

Claims (11)

A hydrogen separator in which a hydrogen separation membrane is formed on a porous substrate,
The hydrogen separation membrane is obtained by dispersing inorganic material particles in a metal having hydrogen separation ability, and the thermal expansion coefficient of the inorganic material particles is a value between the porous substrate and the metal having hydrogen separation ability. der is, and the hydrogen separation membrane, facing the surface of the porous substrate on the surface of the hydrogen separation membrane, by comprising stepwise or continuously graded by dispersing inorganic material particles in a metal having a hydrogen separation performance A hydrogen separator characterized by The hydrogen separator according to claim 1 , wherein the content of the inorganic material particles in the hydrogen separation membrane is 5 to 40% by volume. The hydrogen separator according to claim 1 or 2 , wherein the inorganic material particles have an average particle diameter of 0.1 to 5 µm. The main component of the inorganic material _{particles, SiO 2, Al 2 O 3} , ZrO 2, TiO 2, Cr 2 O hydrogen separator according to any one of claims 1 to 3 is either _3. The hydrogen separator according to any one of claims 1 to 4 , wherein the metal having hydrogen separation ability is palladium, an alloy containing palladium as a main component, or an alloy containing palladium. A hydrogen separator in which a hydrogen separation membrane is formed on a porous substrate,
The hydrogen separation membrane, with one in which the inorganic material particles are dispersed in a metal having a hydrogen separation performance, the thermal expansion coefficient of the inorganic material particles, the value between the metal having a porous substrate and hydrogen resolution A first layer,
A second layer made of a metal laminated on the first layer and having hydrogen separation ability;
A hydrogen separator comprising: First layer, opposite from the surface of the porous substrate on the surface of the first layer, according to claim 6 comprising the inorganic material particles stepwise or continuously graded dispersed in a metal having a hydrogen separation performance Hydrogen separator. The hydrogen separator according to claim 6 or 7 , wherein the content of the inorganic material particles in the first layer is 5 to 40% by volume. The hydrogen separator according to any one of claims 6 to 8 , wherein the inorganic material particles have an average particle diameter of 0.1 to 5 µm. The main component of the inorganic material _{particles, SiO 2, Al 2 O 3} , ZrO 2, TiO 2, Cr 2 O hydrogen separator according to any one of claims 6-9 is either _3. The hydrogen separator according to any one of claims 6 to 10 , wherein the metal having hydrogen separation ability is palladium, an alloy containing palladium as a main component, or an alloy containing palladium.

Images