Hydrogen separation filter and method for manufacturing the same

Abstract

Provided are a hydrogen separation filter capable of purifying hydrogen at a lower temperature than before and a method for manufacturing the same. A hydrogen separation filter includes a porous substrate, a lattice expansion layer formed on the porous substrate and containing a first material, and a hydrogen dissociation permeation layer formed on the lattice expansion layer and containing a second material, the second material being selected from Pd, V, Ta, Ti, Nb, and their alloys, the first material and the second material having the same crystal structure, and the lattice constant a of a first bulk material having the same composition and the same crystal structure as the first material 1，体 and the lattice constant a of a second bulk material having the same composition and the same crystal structure as the second material 2，体 satisfy formula (1): 1.03a 2，体 ≤a 1，体 ≤1.15a 2，体 (1).

Description

Technical Field

[0001] The present invention relates to a hydrogen separation filter and a method for manufacturing the hydrogen separation filter. Background Art

[0002] As a method for purifying hydrogen, a membrane separation method using a metal membrane is known. Patent Document 1 describes a hydrogen separation membrane obtained by forming a palladium thin film or a palladium alloy thin film on the surface of a porous filter, the porous filter including a porous metal substrate and a ceramic porous body covering the pores of the porous metal substrate.

[0003] Prior Art Documents

[0004] Patent Document 1: Japanese Patent Application Laid-Open No. 2017-124364 Summary of the Invention

[0005] Metals capable of selectively permeating hydrogen include palladium (Pd), vanadium (V), tantalum (Ta), titanium (Ti), and niobium (Nb). These metals are liable to embrittle in a hydrogen atmosphere and are used at a high temperature (for example, about 400°C) in order to suppress this. However, a large amount of energy is required to purify hydrogen at a high temperature.

[0006] Therefore, the present invention provides a hydrogen separation filter capable of purifying hydrogen at a lower temperature than in the past and a method for manufacturing the same.

[0007] The present invention includes the following aspects.

[0008] [Item 1]

[0009] A hydrogen separation filter, comprising:

[0010] a porous substrate;

[0011] a lattice expansion layer formed on the porous substrate and containing a first material; and

[0012] a hydrogen dissociation permeation layer formed on the lattice expansion layer and containing a second material, the second material being selected from Pd, V, Ta, Ti, Nb, and their alloys,

[0013] the first material and the second material having the same crystal structure,

[0014] the lattice constant a of a first bulk material having the same composition and the same crystal structure as the first material 1，体 and the lattice constant a of a second bulk material having the same composition and the same crystal structure as the second material 2，体 satisfy the following formula (1):

[0015] 1.03a 2，体 ≤ a 1，体 ≤ 1.15a2，体 (1).

[0016] [Item 2]

[0017] The hydrogen separation filter according to Item 1

[0018] The lattice constant a2 obtained from the interplanar spacing of the crystal plane perpendicular to the interface between the lattice expansion layer and the hydrogen dissociation permeation layer of the second material satisfies the following formula (2):

[0019] a 2，体 < a2 (2).

[0020] [Item 3]

[0021] The hydrogen separation filter according to Item 1

[0022] The lattice constant a2 obtained from the interplanar spacing of the crystal plane perpendicular to the interface between the lattice expansion layer and the hydrogen dissociation permeation layer of the second material satisfies the following formula (3):

[0023] 1.5 ≤ [(a2 - a 2，体 ) / a 2，体 × 100 ≤ 3.6 (3).

[0024] [Item 4]

[0025] The hydrogen separation filter according to any one of Items 1 to 3

[0026] The lattice constant a of the second material obtained from the interplanar spacing of the crystal plane perpendicular to the interface between the lattice expansion layer and the hydrogen dissociation permeation layer 2，界面 、and the lattice constant a of the second material obtained from the interplanar spacing of the crystal plane perpendicular to the interface at the surface of the hydrogen dissociation permeation layer 2，表面 satisfies the following formula (4):

[0027] 0.98 ≤ a 2，表面 / a 2，界面 ≤ 1 (4).

[0028] [Item 5]

[0029] The hydrogen separation filter according to any one of Items 1 to 4

[0030] The thickness of the hydrogen dissociation permeation layer is in the range of 10 to 350 nm.

[0031] [Item 6]

[0032] The hydrogen separation filter according to any one of Items 1 to 5

[0033] The first material is Ag, Au, or Al.

[0034] The second material is Pd.

[0035] [Item 7]

[0036] For the hydrogen separation filter according to Item 6, the first material is Ag.

[0037] [Item 8]

[0038] For the hydrogen separation filter according to any one of Items 1 to 7,

[0039] The total thickness of the lattice expansion layer and the hydrogen dissociation and permeation layer exceeds 7 times the pore diameter of the porous substrate.

[0040] [Item 9]

[0041] For the hydrogen separation filter according to any one of Items 1 to 5,

[0042] The hydrogen separation filter further includes a hydrogen release layer between the porous substrate and the lattice expansion layer, and the hydrogen release layer contains a third material.

[0043] The binding energy of the third material with hydrogen is 230 - 270 KJ / molH.

[0044] [Item 10]

[0045] For the hydrogen separation filter according to Item 9,

[0046] The crystal structure of the third material is the same as that of the first material and the second material.

[0047] [Item 11]

[0048] For the hydrogen separation filter according to Item 10,

[0049] The lattice constant a of the third bulk material having the same composition and the same crystal structure as the third material 3、、体 satisfies the following formula (5):

[0050] 0.8a 1，体 ≤ a 3，体 ≤ 1.0a 1，体 (5).

[0051] [Item 12]

[0052] For the hydrogen separation filter according to any one of Items 9 to 11,

[0053] The first material is Ag,

[0054] The second material is Pd,

[0055] The 3rd material is Cu or Ni.

[0056] [Item 13]

[0057] The hydrogen separation filter according to any one of Items 9 to 11,

[0058] The 1st material is Nb, W or Mo,

[0059] The 2nd material is V,

[0060] The 3rd material is Fe.

[0061] [Item 14]

[0062] A method for manufacturing a hydrogen separation filter is a method for manufacturing the hydrogen separation filter according to any one of Items 1 to 13.

[0063] At a pressure in the range of 1×10 -6 to 1×10 -4 Pa, the 1st material and the 2nd material are sequentially deposited on the porous substrate by vapor deposition.

[0064] [Item 15]

[0065] A method for manufacturing a hydrogen separation filter, a method for manufacturing the hydrogen separation filter according to any one of Items 9 to 12, includes the following steps:

[0066] Deposit Cu as the 3rd material on the porous substrate by electroless plating to form a hydrogen release layer, and the electroless plating uses a copper plating solution containing polyethylene glycol at a concentration in the range of 20 to 40 ppm;

[0067] Deposit the 1st material on the hydrogen release layer by vapor deposition to form a lattice expansion layer; and

[0068] Deposit the 2nd material on the lattice expansion layer by vapor deposition to form a hydrogen dissociation permeation layer.

[0069] With the hydrogen separation filter of the present invention, hydrogen can be purified at a lower temperature than before. Description of the Drawings

[0070] Figure 1 is a schematic cross-sectional view of the hydrogen separation filter of the embodiment.

[0071] Figure 2 is a schematic cross-sectional view of the hydrogen separation filter of the modified embodiment.

[0072] Figure 3A coordinate graph of the time required for chamber evacuation and the hydrogen separation coefficient of the hydrogen separation filter was plotted with respect to the chamber pressure when forming the Ag layer and the Pd layer in Examples 1 to 5.

[0073] Figure 4 A coordinate graph of the Cu film formation rate and the hydrogen separation coefficient of the hydrogen separation filter was plotted with respect to the polyethylene glycol concentration of the electroless plating solution used in Examples 6 to 10.

[0074] Explanation of reference numerals

[0075] 1: Hydrogen separation filter, 20: Porous substrate, 40: Lattice expansion layer, 60: Hydrogen dissociation permeation layer, 62: Interface between the lattice expansion layer and the hydrogen dissociation permeation layer, 64: Surface of the hydrogen dissociation permeation layer, 80: Hydrogen release layer Detailed implementation manners

[0076] Hereinafter, the implementation manners will be described with appropriate reference to the drawings. In the drawings referred to in the following description, the same reference numerals are assigned to the same components or components having the same functions, and repeated descriptions are sometimes omitted. For ease of explanation, the dimensional ratios and shapes of the respective parts in the drawings are exaggerated and sometimes different from the actual dimensional ratios and shapes. In addition, in the present application, the numerical ranges represented by the symbol "~" respectively include the numerical values described before and after the symbol "~" as the lower limit value and the upper limit value. In the present application, "vertical" includes not only completely vertical but also substantially vertical, and "parallel" includes not only completely parallel but also substantially parallel. In addition, in the present application, unless otherwise specified in the context, "on ~" includes both "directly on ~" and "indirectly on ~".

[0077] I Implementation manners

[0078] Figure 1 The hydrogen separation filter 1 of the shown implementation manner includes a porous substrate 20, a lattice expansion layer 40 formed on the porous substrate 20, and a hydrogen dissociation permeation layer 60 formed on the lattice expansion layer 40. In the present implementation manner, the lattice expansion layer 40 can be directly formed on the porous substrate 20, and the hydrogen dissociation permeation layer 60 can be directly formed on the lattice expansion layer 40.

[0079] The porous substrate 20 can be formed of, for example, a metal, a metal oxide, or a resin, and can be formed of a metal oxide due to its high durability. Examples of the metal oxide include alumina, zirconia, and zeolite. In particular, alumina is preferred because of its low cost. The porous substrate 20 can have any shape such as a flat plate shape or a cylindrical shape.

[0080] The porous substrate 20 has pores through which hydrogen can pass. The pores are blocked by the lattice expansion layer 40 and the hydrogen dissociation permeation layer 60. The average diameter of the pores can be, for example, in the range of 1 to 100 nm. By having the pore diameter within the above range, the porous substrate 20 has sufficient hydrogen permeability, and it is easy to block the pores by the lattice expansion layer 40 and the hydrogen dissociation permeation layer 60 without making the lattice expansion layer 40 and the hydrogen dissociation permeation layer 60 too thick. In addition, the pore diameter can be 1 / 7 times or less of the total thickness of the hydrogen dissociation permeation layer 60 and the lattice expansion layer 40. Here, the pore size distribution of the porous substrate 20 can be obtained by the mercury intrusion method based on JIS R 1655:2003. The mercury intrusion method is a method of applying pressure to immerse mercury into open pores, obtaining the relationship between the volume of mercury immersed in the open pores and the pressure value applied at this time, and based on this result, assuming the open pores as cylindrical and calculating the open pore diameter according to the Washburn formula.

[0081] The porosity of the porous substrate 20 can be in the range of 30% to 50%. Thereby, the porous substrate 20 can have sufficient hydrogen permeability while having sufficient mechanical strength.

[0082] The lattice expansion layer 40 contains the first material, or consists essentially of the first material, or consists of the first material. The hydrogen dissociation permeation layer 60 contains the second material, or consists essentially of the second material, or consists of the second material. In the present application, "contains" means that additional components can be contained, including "consisting of" and "consisting essentially of". "Consisting essentially of" means that additional components that do not substantially adversely affect the functions of the lattice expansion layer 40 or the hydrogen dissociation permeation layer 60 can be contained. "Consisting of" means that only the recited materials are contained, but does not exclude the inclusion of unavoidable impurities.

[0083] The second material contained in the hydrogen dissociation permeation layer 60 is selected from Pd, V, Ta, Ti, Nb, and their alloys. The hydrogen dissociation permeation layer 60 dissociates and adsorbs hydrogen molecules on its surface 64 to generate hydrogen atoms. The hydrogen atoms diffuse in the hydrogen dissociation permeation layer 60, reach the interface 62 between the lattice expansion layer 40 and the hydrogen dissociation permeation layer 60, further diffuse in the lattice expansion layer 40, recombine at the interface 42 between the lattice expansion layer 40 and the porous substrate 20 to form hydrogen molecules, and are released from the lattice expansion layer 40. The hydrogen molecules are discharged from the hydrogen separation filter 1 through the porous substrate 20. Thereby, the hydrogen separation filter 1 can selectively permeate hydrogen. In particular, Pd has high hydrogen dissociation permeability even at low temperatures below 300 °C, so it is suitable as the second material.

[0084] The first material contained in the lattice expansion layer 40 has the same crystal structure as the second material. In addition, the first material in the lattice expansion layer 40 and the second material in the hydrogen dissociation permeation layer 60 can have the same crystal orientation.

[0085] The first bulk material having the same composition and the same crystal structure as the first material has a lattice constant a 1，体 , and the second bulk material having the same composition and the same crystal structure as the second material has a lattice constant a 2，体 , the lattice constant a 1，体 and the lattice constant a 2，体 satisfy the following formula (1):

[0086] 1.03a 2，体 ≤ a 1，体 ≤ 1.15a 2，体 (1).

[0087] Furthermore, in the case where the first material and the second material have a crystal structure other than a cubic crystal, the lattice constants of the same crystal axes of the first material and the second material satisfy formula (1). Here, the bulk material refers to a self-supporting, i.e., completely relaxed material not supported by other members. By making the first material and the second material have the same crystal structure and a composition satisfying formula (1), the lattice constant a2 of the second material in the hydrogen dissociation permeation layer 60 can be made larger than the lattice constant a of the second bulk material 2，体 .

[0088] For example, when the second material is Pd having a face-centered cubic lattice (fcc) structure, the first material can be Al, Au, or Ag having an fcc structure. In particular, considering cost and oxidation resistance, Ag is preferred. When the second material is V having a body-centered cubic lattice (bcc) structure, the first material can be Mo, W, or Nb having a bcc structure. When the second material is Ta having a bcc structure, the first material can be V, Mo, W, or Nb having a bcc structure. Furthermore, the lattice constants of the bulk materials of these metals are shown in Table 1

[0089] Table 1

[0090] Metal Crystal Structure Lattice Constant of Bulk Material [nm] Pd fcc 0.38898 Al fcc 0.40496 Au fcc 0.40786 Ag fcc 0.40862 Ta bcc 0.28665 V bcc 0.30300 Mo bcc 0.31399 W bcc 0.31560 Nb bcc 0.32941

[0091] The lattice constant a2 of the second material in the hydrogen dissociation permeation layer 60 satisfies the following formula (2):

[0092] a 2，体 < a2 (2).

[0093] In particular, the lattice constant a2 of the second material can satisfy the following formula (3):

[0094] 1.5 ≤ [(a2 - a 2，体 ) / a 2，体 × 100 ≤ 3.6 (3).

[0095] Here, the lattice constant a2 of the second material is the lattice constant obtained from the interplanar spacing of the crystal plane perpendicular to the interface 62 between the lattice expansion layer 40 and the hydrogen dissociation permeation layer 60. Specifically, using a transmission electron microscope (TEM), electron beam diffraction patterns of the second material at the surface 64 of the hydrogen dissociation permeation layer 60 and its vicinity, at the interface 62 between the lattice expansion layer 40 and the hydrogen dissociation permeation layer 60 and its vicinity, and at an intermediate position therebetween are obtained. Based on each electron beam diffraction pattern, the lattice constant is obtained from the interplanar spacing of the crystal plane perpendicular to the interface 62 between the lattice expansion layer 40 and the hydrogen dissociation permeation layer 60, and the average value of the obtained values is calculated, whereby the lattice constant a2 of the second material can be obtained. The above formula (2) indicates that the lattice of the second material in the hydrogen dissociation permeation layer 60 expands at least in the direction parallel to the interface 62 compared to the completely relaxed state. The lattice of the second material in the hydrogen dissociation permeation layer 60 may also expand in the direction perpendicular to the interface 62. Conventionally, when hydrogen diffuses in the lattice of the hydrogen dissociation permeation layer at low temperature, the lattice repeatedly expands and contracts, resulting in embrittlement. However, in the hydrogen separation filter 1 of the present embodiment, the expansion and contraction of the lattice caused by hydrogen diffusion are suppressed by the lattice expansion of the hydrogen dissociation permeation layer 60, thereby suppressing the embrittlement of the hydrogen dissociation permeation layer 60 at low temperature. Therefore, the hydrogen separation filter 1 of the present embodiment can purify hydrogen at a lower temperature than in the past.

[0096] In addition, the lattice constant a of the second material at the interface 62 between the lattice expansion layer 40 and the hydrogen dissociation permeation layer 60 2，界面 and the lattice constant a of the second material at the surface 64 of the hydrogen dissociation permeation layer 60 2，表面 may satisfy the following formula (4):

[0097] 0.98 ≤ a 2，表面 / a 2，界面 ≤ 1 (4).

[0098] In addition, [(a 2，表面 - a 2，体 ) / a 2，体 × 100 and [(a 2，界面 - a 2，体 ) / a 2，体 × 100 may be in the range of 1.5 to 3.6.

[0099] Here, the lattice constant a of the second material at the interface 62 2，界面 is the lattice constant obtained from the interplanar spacing of the crystal plane perpendicular to the interface 62 at the interface 62 and its vicinity. The lattice constant of the second material at the surface 64 a2，表面It refers to the lattice constant obtained based on the interplanar spacing of crystal planes perpendicular to the interface 62 on the surface 64 and in its vicinity. They can be obtained from the electron beam diffraction pattern using TEM. The above formula (4) indicates that the lattice of the second material extends over the entire hydrogen dissociation permeation layer 60, thereby suppressing the hydrogen embrittlement of the entire hydrogen dissociation permeation layer 60.

[0100] The total thickness of the lattice expansion layer 40 and the hydrogen dissociation permeation layer 60 can exceed 7 times the pore diameter of the porous substrate 20. Thus, the pores can be effectively blocked by the lattice expansion layer 40 and the hydrogen dissociation permeation layer 60, and the hydrogen separation filter 1 can have good hydrogen separation performance. From the viewpoint of saving the raw material cost and manufacturing time of the hydrogen separation filter 1, the total thickness of the lattice expansion layer 40 and the hydrogen dissociation permeation layer 60 can be 700 nm or less. In addition, from the viewpoint of balancing the saving of raw material cost and manufacturing time and hydrogen separation performance, the thickness of the hydrogen dissociation permeation layer 60 can be in the range of 10 - 350 nm.

[0101] The hydrogen separation filter 1 of the present embodiment can be manufactured by the following process: depositing the first material on the porous substrate 20 by vapor deposition to form the lattice expansion layer 40, and then depositing the second material on the lattice expansion layer 40 by vapor deposition to form the hydrogen dissociation permeation layer 60. Compared with the plating method, the vapor deposition method has the advantage that the deposition amount required to block the pores of the porous substrate 20 is small, and it can reduce the usage amount of the second material, which is a rare and expensive metal. In addition, compared with the CVD method, the vapor deposition method is also advantageous in that fewer impurities are mixed in the formed layer, and compared with the sputtering method, the device is cheaper.

[0102] It is preferable to use a cryopump for exhausting the film deposition chamber of the vapor deposition apparatus. The vapor deposition can be carried out under a pressure in the range of 1×10 -6 ~1×10 -4 Pa. If the pressure is 1×10 -6 Pa or more, the exhaust of the film deposition chamber will not take too much time, so the hydrogen separation filter 1 can be manufactured with good productivity. In addition, by making the pressure in the film deposition chamber 1×10 -4 Pa or less, the defects existing in the lattice expansion layer 40 and the hydrogen dissociation permeation layer 60 are few enough, and thus the hydrogen separation filter 1 can have good hydrogen separation performance.

[0103] II Deformation Mode

[0104] The present invention is not limited to the above embodiment, and various design changes can be made without departing from the spirit of the present invention described in the claims. For example, in the above embodiment, the lattice expansion layer 40 is directly formed on the porous substrate 20, but as Figure 2As shown, a hydrogen release layer 80 may also be formed between the lattice expansion layer 40 and the porous substrate 20. That is, the lattice expansion layer 40 can be indirectly formed on the porous substrate 20.

[0105] Figure 2 The hydrogen separation filter 3 of the shown modified form includes: a porous substrate 20, a lattice expansion layer 40 indirectly formed on the porous substrate 20, a hydrogen dissociation permeation layer 60 formed on the lattice expansion layer 40, and a hydrogen release layer 80 formed between the porous substrate 20 and the lattice expansion layer 40. In this modified form, the hydrogen release layer 80 can be directly formed on the porous substrate 20, the lattice expansion layer 40 can be directly formed on the hydrogen release layer 80, and the hydrogen dissociation permeation layer 60 can be directly formed on the lattice expansion layer 40.

[0106] The porous substrate 20, the lattice expansion layer 40, and the hydrogen dissociation permeation layer 60 are the same as those in the above-described embodiment, and thus the description thereof is omitted. Further, in this modified form, the pores of the porous substrate 20 are blocked by the hydrogen release layer 80, the lattice expansion layer 40, and the hydrogen dissociation permeation layer 60. Therefore, compared with the above-described embodiment in which only the lattice expansion layer 40 and the hydrogen dissociation permeation layer 60 block the pores of the porous substrate 20, the total thickness of the lattice expansion layer 40 and the hydrogen dissociation permeation layer 60 can be reduced.

[0107] The hydrogen release layer 80 contains a third material, or is substantially composed of a third material, or is composed of a third material. The third material is a material having a binding energy with hydrogen in the range of 230 to 270 KJ / molH. Thereby, on the surface 82 of the hydrogen release layer 80 (the interface 82 between the porous substrate 20 and the hydrogen release layer 80), hydrogen atoms can recombine and be released from the hydrogen release layer 80.

[0108] For example, the third material is selected from Cu, Ni, Rh, Pd, Ir, Pt, Fe, Co, Ru, and their alloys. The binding energy of these metals with hydrogen together with the crystal structure and lattice constant is shown in Table 2.

[0109] Table 2

[0110]

[0111] In addition, the third material may be a material cheaper than the first material and the second material. As described above, in the hydrogen separation filter 3 of this modified embodiment, the pores of the porous substrate 20 are blocked by the hydrogen release layer 80, the lattice expansion layer 40, and the hydrogen dissociation permeation layer 60. Therefore, compared with the hydrogen separation filter 1 of the above embodiment in which the pores of the porous substrate 20 are blocked only by the lattice expansion layer 40 and the hydrogen dissociation permeation layer 60, the total thickness of the lattice expansion layer 40 and the hydrogen dissociation permeation layer 60 can be reduced. By forming the hydrogen release layer 80 with a third material cheaper than the first material and the second material, the raw material cost of the hydrogen separation filter 3 can be reduced.

[0112] The third material may have the same crystal structure as the first material and the second material. In addition, the lattice constant a of the third bulk material having the same composition and the same crystal structure as the third material 3，体 may satisfy the following formula (5):

[0113] 0.8a 1，体 ≤a 3，体 ≤1.0a 1，体 (5).

[0114] Thereby, the stress caused by the difference in the lattice constant a of the first bulk material 1，体 and the lattice constant a of the second bulk material 2，体 can be compensated.

[0115] For example, when the first material is Ag and the second material is Pd, the third material may be Cu or Ni, particularly Cu. When the first material is Nb, W, or Mo and the second material is V, the third material may be Fe.

[0116] The total thickness of the lattice expansion layer 40, the hydrogen dissociation permeation layer 60, and the hydrogen release layer 80 may exceed 7 times the pore diameter of the porous substrate 20. Thereby, the pores can be reliably blocked by the lattice expansion layer 40, the hydrogen dissociation permeation layer 60, and the hydrogen release layer 80, and the hydrogen separation filter 3 can have good hydrogen separation performance. From the viewpoint of saving the raw material cost and manufacturing time of the hydrogen separation filter 3, the total thickness of the lattice expansion layer 40, the hydrogen dissociation permeation layer 60, and the hydrogen release layer 80 may be 700 nm or less. In addition, from the viewpoint of balancing the saving of the raw material cost and manufacturing time of the hydrogen separation filter 3 and the hydrogen separation property, the thickness of the hydrogen dissociation permeation layer 60 may be in the range of 10 to 350 nm.

[0117] The hydrogen release layer 80 may have a single-layer structure or a multilayer structure including two or more layers.

[0118] The hydrogen separation filter 3 can selectively allow hydrogen to pass through as described below. On the surface 64 of the hydrogen dissociation permeation layer 60, hydrogen molecules are dissociated and adsorbed to generate hydrogen atoms. The hydrogen atoms diffuse within the hydrogen dissociation permeation layer 60, the lattice expansion layer 40, and the hydrogen release layer 80, recombine at the interface 82 between the hydrogen release layer 80 and the porous substrate 20 to form hydrogen molecules, and are released from the hydrogen release layer 80. The hydrogen molecules are discharged from the hydrogen separation filter 3 through the porous substrate 20.

[0119] The hydrogen separation filter 3 of this modified embodiment can be manufactured by a method including the following steps: a step of depositing a third material on the porous substrate 20 by electroless plating to form the hydrogen release layer 80; a step of depositing a first material on the hydrogen release layer 80 by vapor deposition to form the lattice expansion layer 40; and a step of depositing a second material on the lattice expansion layer 40 by vapor deposition to form the hydrogen dissociation permeation layer 60. Furthermore, in this method, the step of forming the lattice expansion layer 40 and the step of forming the hydrogen dissociation permeation layer 60 can also be collectively referred to as a step of indirectly and sequentially depositing the first material and the second material on the porous substrate 20.

[0120] In the step of forming the hydrogen release layer 80, any electroless plating method can be used according to the type of the third material. The catalyst for electroless plating can also be previously imparted to the porous substrate 20. Since the electroless plating method generally has a faster film formation rate than the vapor deposition method, the hydrogen separation filter 3 of the modified embodiment can be manufactured in a shorter manufacturing time compared to the hydrogen separation filter 1 of the above-described embodiment.

[0121] When the third material is Cu, the copper plating solution for electroless plating can contain copper sulfate, formaldehyde, and polyethylene glycol. The copper plating solution can contain polyethylene glycol at a concentration in the range of 20 to 40 ppm based on the total weight of the copper plating solution. By making the concentration of polyethylene glycol 20 ppm or more, the hydrogen separation filter 3 can have good hydrogen separation performance. If the concentration of polyethylene glycol is 40 ppm or less, the film formation rate of Cu is fast enough, so the hydrogen separation filter 3 can be manufactured with good productivity.

[0122] The method for forming the lattice expansion layer 40 and the hydrogen dissociation permeation layer 60 by vapor deposition is the same as the method in the hydrogen separation filter 1 of the above-described embodiment, so the detailed description is omitted.

[0123] Examples

[0124] Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to these examples. I. A hydrogen separation filter sequentially including a porous substrate, a lattice expansion layer, and a hydrogen dissociation permeation layer

[0125] (1) Fabrication of the hydrogen separation filter

[0126] Examples 1 - 5

[0127] A porous ceramic substrate mainly composed of alumina (N-99EP manufactured by Nishimura Ceramics Co., Ltd., average pore diameter 100 nm, porosity 35%, hereinafter simply referred to as "substrate") was placed in the film formation chamber of an evaporation device. Evaporation units for Ag and Pd were installed in the film formation chamber, and a rotary pump and a cryopump were connected. The chamber was evacuated to about 40 Pa with the rotary pump, and then to the pressure shown in Table 3 with the cryopump. Ag was evaporated on the substrate to form an Ag layer, and then Pd was evaporated on the Ag layer to form a Pd layer. In this way, a hydrogen separation filter was fabricated. The total thickness of the Ag layer and the Pd layer was about 700 nm.

[0128] Comparative Example

[0129] A hydrogen separation filter was fabricated in the same manner as in Example 4, except that an Ag layer was not formed and a Pd layer with a thickness of about 700 nm was directly formed on the substrate.

[0130] (2) Measurement of lattice constant

[0131] For the hydrogen separation filters of Examples 1 - 5, electron diffraction patterns of the Pd layer at the interface between the Pd layer and the Ag layer and its vicinity, the surface of the Pd layer and its vicinity, and the middle position of the Pd layer were obtained using TEM. Based on these electron diffraction patterns, the interplanar spacing of Pd(110) perpendicular to the interface between the Ag layer and the Pd layer at each position was determined. Using these interplanar spacings, the lattice constant a of Pd at the interface between the Ag layer and the Pd layer was obtained Pd，界面 , the lattice constant a of Pd at the surface of the Pd layer Pd，表面 and the lattice constant at the middle position were obtained, and their average value a pd was calculated. In addition, the ratio a Pd，表面 / a Pd，界面 was calculated. For the hydrogen separation filter of the comparative example, the lattice constant a of Pd at the interface between the substrate and the Pd layer Pd，界面 , the lattice constant a of Pd at the surface of the Pd layer Pd，表面 and the lattice constant at the middle position were obtained in the same manner, and their average value a pd was calculated. Furthermore, the ratio a Pd，表面 / a Pd，界面 was obtained. The results are shown in Table 3.

[0132] In Examples 1 - 5, the lattice constant a pd was larger than the lattice constant a pd，体 (0.38898 nm) of bulk Pd. On the other hand, in the comparative example, the lattice constant a pd was the same as the lattice constant a pd，体Roughly equal. This result shows that by forming a Pd layer on the Ag layer, the lattice of Pd expands in the direction parallel to the interface between the Ag layer and the Pd layer. Additionally, in Examples 1-5, [(a pd -a pd，体 ) / a pd，体 ×100, [(a pd，表面 -a pd，体 ) / a pd，体 ×100, and [(a pd，界面 -a pd，体 ) / a pd，体 ×100 are in the range of 1.5 to 3.6.

[0133] In Examples 1-5, the ratio a Pd，表面 / a Pd，界面 is in the range of 0.98 to 1, indicating that the Pd lattice expands sufficiently throughout the Pd layer.

[0134] (3) Evaluation of voids in the Pd layer

[0135] By Auger electron spectroscopy analysis, surface element mapping images of the hydrogen separation filters of Examples 1-5 and the comparative example were obtained. Only Pd was detected in any of the hydrogen separation filters, and neither Ag nor Al was detected. From these results, it was confirmed that in any of the hydrogen separation filters, the Pd layer does not have voids.

[0136] (4) Hydrogen separation performance evaluation

[0137] The hydrogen separation filters of Examples 1-5 and the comparative example were heated to 100 °C, and a mixed gas of hydrogen and nitrogen (1% hydrogen) was passed through. The hydrogen concentration C0 in the mixed gas before passing through the hydrogen separation filter and the hydrogen concentration C in the mixed gas after passing through the hydrogen separation filter were measured, and the hydrogen separation coefficient S was calculated based on the following formula. The results are shown in Table 3.

[0138] S = (C / (1 - C)) / (C0 / (1 - C0))

[0139] The hydrogen separation coefficient of the hydrogen separation filters of Examples 1-5 is greater than that of the hydrogen separation filters of the comparative example. This result shows that by the expansion of the Pd lattice, the embrittlement of the Pd layer is suppressed, and thus, the hydrogen separation performance at a low temperature of 100 °C is improved.

[0140] (5) Relationship between film formation conditions and hydrogen separation performance and productivity

[0141] Figure 3 is a coordinate diagram depicting the time required for evacuation of the chamber and the hydrogen separation coefficient of the hydrogen separation filter with respect to the chamber pressure when forming the Ag layer and the Pd layer. The chamber pressure is 1×10 -4Particularly high hydrogen separation coefficients were obtained when the pressure was below Pa. On the other hand, when the chamber pressure was 1×10 -6 Pa or higher, the evacuation of the chamber was completed in a sufficiently short time. From this result, it is advantageous in manufacturing to perform vapor deposition at a pressure in the range of 1×10 -6 ~1×10 -4 Pa.

[0142] Table 3

[0143]

[0144] II A hydrogen separation filter having a porous substrate, a hydrogen release layer, a lattice expansion layer, and a hydrogen dissociation and permeation layer in sequence

[0145] (1) Fabrication of the hydrogen separation filter

[0146] Examples 6 - 10

[0147] i) Measurement of the electroless plating Cu film formation rate

[0148] A porous ceramic substrate mainly composed of alumina (N - 99EP manufactured by Nishimura Ceramics Co., Ltd., average pore diameter 100 nm, porosity 35%, hereinafter simply referred to as "substrate") was immersed in an aqueous stannous chloride solution, and then washed with pure water. Subsequently, the substrate was immersed in an aqueous palladium chloride solution, and then washed with pure water. Thus, a palladium catalyst was imparted to the substrate.

[0149] An electroless plating solution containing copper sulfate, formaldehyde, and polyethylene glycol (PEG) was prepared. The PEG concentration in the electroless plating solution is shown in Table 4. The substrate imparted with the palladium catalyst was immersed in the electroless plating solution for a specified time to deposit Cu on the substrate. The Cu film formation rate was obtained by dividing the difference in weight before and after Cu deposition by the immersion time. The results are shown in Table 4.

[0150] ii) Fabrication of the hydrogen separation filter

[0151] A substrate imparted with a palladium catalyst was prepared in the same manner as in i). In the plating solution used in i), the substrate imparted with the palladium catalyst was immersed for a specified time to deposit Cu on the substrate and form a Cu layer.

[0152] The substrate on which the Cu layer was formed was placed in the film formation chamber of a vapor deposition apparatus. Evaporation units for Ag and Pd were provided in the film formation chamber, and a rotary pump and a cryopump were connected. The chamber was evacuated to about 40 Pa with the rotary pump, and then evacuated to a pressure of 1×10 -4 Pa with the cryopump. Ag was vapor - deposited on the Cu layer to form an Ag layer, and Pd was vapor - deposited on the Ag layer to form a Pd layer. Thus, a hydrogen separation filter was fabricated. The total thickness of the Cu layer, Ag layer, and Pd layer was approximately 700 nm.

[0153] (2) Measurement of lattice constant

[0154] For the hydrogen separation filters of Examples 6 - 10, electron diffraction patterns of the Pd layer were obtained using TEM at the interface between the Pd layer and the Ag layer and its vicinity, the surface of the Pd layer and its vicinity, and intermediate positions thereof. From these electron diffraction patterns, the interplanar spacing of Pd(110) perpendicular to the interface between the Ag layer and the Pd layer was determined at each position. The lattice constant of Pd at each position was obtained from these interplanar spacings, and their average value a was obtained. pd In any of Examples 6 - 10, the lattice constant a pd was about 1.03 times the lattice constant a pd，体 (0.38898 nm) of the Pd bulk.

[0155] (3) Hydrogen separation performance evaluation

[0156] The hydrogen separation performance of the hydrogen separation filters of Examples 6 - 10 was evaluated in the same manner as in Examples 1 - 5. The results are shown in Table 4.

[0157] (4) Relationship between PEG concentration, hydrogen separation performance, and productivity

[0158] Figure 4 A coordinate diagram of the Cu film formation rate and the hydrogen separation coefficient of the hydrogen separation filter was plotted with respect to the PEG concentration in the electroless plating solution. A particularly high hydrogen separation coefficient was obtained when the PEG concentration was 20 ppm or more. In addition, when the PEG concentration was 40 ppm or less, the Cu film formation rate was fast enough. From this result, it was shown that it was advantageous in manufacturing to use an electroless copper plating solution containing PEG at a concentration in the range of 20 - 40 ppm.

[0159] Table 4

[0160]

Claims

1. A hydrogen separation filter, comprising: A porous substrate; A lattice expansion layer formed on the porous substrate and containing a first material; and A hydrogen dissociation permeation layer formed on the lattice expansion layer and containing a second material, the second material being selected from Pd, V, Ta, Ti, Nb, and their alloys, The first material and the second material have the same crystal structure, The lattice constant a of the first bulk material having the same composition and the same crystal structure as the first material 1，体 and the lattice constant a of the second bulk material having the same composition and the same crystal structure as the second material 2，体 satisfy the following formula (1): 1.03a 2，体 ≤ a 1，体 ≤ 1.15a 2，体 (1) 2. The hydrogen separation filter according to claim 1, The lattice constant a2 obtained from the interplanar spacing of the crystal plane perpendicular to the interface between the lattice expansion layer and the hydrogen dissociation permeation layer of the second material satisfies the following formula (2): a 2，体 <a2 (2).

3. The hydrogen separation filter according to claim 1, The lattice constant a2 obtained from the interplanar spacing of the crystal plane perpendicular to the interface between the lattice expansion layer and the hydrogen dissociation permeation layer of the second material satisfies the following formula (3): 1.5 ≤ [(a2 - a 2，体 ) / a 2，体 × 100 ≤ 3.6 (3).

4. The hydrogen separation filter according to any one of claims 1 to 3, The lattice constant a of the second material obtained from the interplanar spacing of the crystal plane perpendicular to the interface between the lattice expansion layer and the hydrogen dissociation permeation layer 2，界面 and the lattice constant a of the second material obtained from the interplanar spacing of the crystal plane perpendicular to the interface at the surface of the hydrogen dissociation permeation layer 2，表面 satisfy the following formula (4): 0.98 ≤ a 2，表面 / a 2，界面 ≤ 1 (4).

5. The hydrogen separation filter according to any one of claims 1 to 3, The thickness of the hydrogen dissociation permeation layer is in the range of 10 to 350 nm.

6. The hydrogen separation filter according to any one of claims 1 to 3, The first material is Ag, Au, or Al, The second material is Pd.

7. The hydrogen separation filter according to claim 6, The first material is Ag.

8. The hydrogen separation filter according to any one of claims 1 to 3, The total thickness of the lattice expansion layer and the hydrogen dissociation permeation layer exceeds 7 times the pore diameter of the porous substrate.

9. The hydrogen separation filter according to any one of claims 1 to 3, The hydrogen separation filter further includes a hydrogen release layer between the porous substrate and the lattice expansion layer, the hydrogen release layer containing a third material, The binding energy of the third material with hydrogen is 230 to 270 KJ / molH.

10. The hydrogen separation filter according to claim 9, The crystal structure of the third material is the same as that of the first material and the second material.

11. The hydrogen separation filter according to claim 10, The lattice constant a of the third bulk material having the same composition and the same crystal structure as the third material 3， The bulk satisfies the following formula (5): 0.8a 1，体 ≤a 3，体 ≤1.0a 1，体 (5).

12. The hydrogen separation filter according to any one of claims 9 to 11, The first material is Ag, The second material is Pd, The third material is Cu or Ni.

13. The hydrogen separation filter according to any one of claims 9 to 11, The first material is Nb, W, or Mo, The second material is V, The third material is Fe.

14. A method for manufacturing a hydrogen separation filter, which is a method for manufacturing the hydrogen separation filter according to any one of claims 1 to 13, comprising the following steps: Under a pressure in the range of 1×10 -6 to 1×10 -4 Pa, the first material and the second material are sequentially deposited on the porous substrate by vapor deposition method.

15. A method for manufacturing a hydrogen separation filter, which is a method for manufacturing the hydrogen separation filter according to any one of claims 9 to 12, comprising the following steps: Depositing Cu as the third material on the porous substrate by electroless plating to form a hydrogen release layer, and the electroless plating method uses a copper plating solution containing polyethylene glycol at a concentration in the range of 20 to 40 ppm; Depositing the first material on the hydrogen release layer by evaporation to form a lattice expansion layer; and The second material is deposited on the lattice expansion layer by vapor deposition to form a hydrogen dissociation permeation layer.

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