JP4341915B2 - Hydrogen separation material and method for producing the same - Google Patents

Description

  The present invention relates to a hydrogen separator and a method for producing the hydrogen separator. More specifically, the present invention relates to a hydrogen separation material (porous material) provided with a hydrogen separation membrane having a high hydrogen permeation rate, and a method for producing the same.

Since the porous ceramic film is excellent in terms of heat resistance, chemical resistance, etc., it is applied to gas separation at high temperature and separation of various organic solvent mixtures. A gas separation device using a membrane is expected as an energy-saving device because it does not involve phase change, can be expected to simplify the device and operation, and can be continuously operated.
As a constituent element of such a porous ceramic film, high silicate component glass (for example, Vycor glass) can be mentioned. The glass film is excellent in heat resistance and corrosion resistance. However, since the pore diameter is as large as about 40 angstroms or more, there is a disadvantage that the separation factor is low when used for separation of hydrogen and the like. Therefore, it has been studied to form a thin-film hydrogen separation layer having a smaller pore diameter on the surface of such a high silicate glass as a support. As a method for forming such a thin film separation layer that can selectively permeate hydrogen, a sol-gel method, a CVD method, a hydrothermal synthesis method, an electrode oxidation method, and the like have been proposed. Among these methods, it is reported that a silica thin film formed by a sol-gel method (see Non-Patent Document 1) or a CVD method using silane or chloride can provide high separation performance. Patent Documents 1 and 3 disclose a method of treating the surface with a silane coupling agent in order to improve the durability of such a separation membrane. Nevertheless, higher hydrogen separation performance is required for use as a hydrogen gas separator.

  For this reason, in Patent Document 2, in order to improve the hydrogen separation performance, a group 8 metal of the periodic table is introduced into the silica sol to form a silica film, or the silica film is added to the group 8 metal-containing solution of the periodic table. A hydrogen separation material in which the metal is introduced into the membrane by immersion is disclosed. By including this group 8 metal in the periodic table in the silica film, the metal has excellent hydrogen affinity, so the affinity of hydrogen to the silica film is increased, and on the inner wall surface of the pore through the metal. It is said that hydrogen diffusion is activated and hydrogen permselectivity can be improved.

JP 2001-29760 A JP 2001-120969 A JP 2002-248326 A Shoji Asaeda "Catalyst", Catalysis Society of Japan (1994), Vol. 36, No. 4, pp. 238-245

However, if it is attempted to introduce metal particles into the silica skeleton, it is difficult to finely and uniformly disperse the metal particles in the silica gel, so that the metal particles tend to aggregate and become larger. For this reason, the ratio of the metal particle diameter to the pore diameter of the silica membrane increases, and as a result, there is a possibility that the pores are partially blocked and the hydrogen permeation rate is lowered. Alternatively, by immersing the silica film in a metal solution, when trying to introduce metal particles into the silica film surface and pores, a silica film having a larger pore diameter than the metal particles, for example, an average pore diameter of 1 nm or more Since it is necessary to use a silica membrane, the hydrogen separation performance of the silica membrane itself is lowered.
Therefore, the present invention has been developed to solve such conventional problems, and an object of the present invention is to provide a hydrogen separation material having a high hydrogen permselectivity and a high hydrogen permeation rate, and a method for producing the same. To do.

The method for producing a hydrogen separator provided by the present invention includes a step of preparing a porous body and a step of supporting a complex. Here, in the porous body preparation step, a porous body having a hydrogen separation layer (that is, a hydrogen separation membrane) having a pore size that can selectively permeate hydrogen is prepared at least in part. In addition, the complex supporting step is composed of an element belonging to any of Group 5, Group 8, Group 9 and Group 10 of the long-period type periodic table in the porous hydrogen separation layer (typically the surface layer). A complex having at least one metal element selected from the group as at least one central metal is supported . And producing a hydrogen separation material characterized in that the complex is supported on the outer surface of the hydrogen separation layer and the inner wall surface of the pores by including no firing treatment during and after the complex supporting step. It is a method to do .

  In the method having such a configuration, the complex is supported on the porous body. The complex can be finely and uniformly highly dispersed without large aggregation on the surface of the porous body, and the particle size of the carrier is relatively small. Therefore, using a porous body having a hydrogen separation layer having a pore size that can selectively permeate hydrogen, even if the metal complex particles are supported on the outer surface of the hydrogen separation layer of the porous body and in the pores, The pore diameter of the hydrogen separation layer (typically the surface layer) is maintained, and the hydrogen permeability is hardly affected. For this reason, a reduction in hydrogen permeation rate is prevented. In addition, the complex has at least one metal element selected from the group consisting of Group 5, Group 8, Group 9, and Group 10 elements of the long-period type periodic table as at least one central metal. Such a metal has a high affinity for hydrogen. Therefore, according to the method of the present invention, it is possible to provide a hydrogen separation material in which the hydrogen concentration in the pores of the hydrogen separation layer (typically the surface layer) is increased and the hydrogen permeation rate is improved.

  Preferably, the central metal of the complex is at least one selected from the group consisting of Rh, Ru, Pd, Pt, Ir, V, Ni, Co, and Fe among the above. Among these, it is preferable that the complex contains Pd as a central metal. These metals (particularly Pd) are particularly excellent in affinity for hydrogen and excellent in the effect of improving the hydrogen permeation rate. A base metal such as Co is preferable because it is excellent in the effect of improving the hydrogen permeation rate and is economical.

  The complex used here is preferably an acetate complex and / or an acetylacetonato complex. All of these complexes exhibit moderate reactivity, and the central metal can be easily and finely and uniformly supported on the hydrogen separation layer (typically the surface layer) of the porous body.

  In a preferred embodiment of this method, the surface layer of the porous body is subjected to a surface activation treatment on at least the hydrogen separation layer before the complex supporting step. In this specification, the “surface activation treatment” refers to a treatment that can chemically or physically change at least the surface of the porous body in the hydrogen separation layer and activate the reactivity with the complex on the surface. Therefore, with such a configuration, the site where the complex is supported can be activated or increased, and the complex support treatment time and the complex support amount can be controlled. Such surface activation treatment preferably includes, for example, any one of heat treatment, laser treatment, plasma treatment, acid treatment, and surfactant treatment. Among these, the plasma treatment is particularly suitable for forming a hydroxy site in the porous hydrogen separation layer and facilitating the coordinate bond with the central metal.

  In the complex supporting step, the porous body is preferably immersed in a solution containing the complex. The complex can be easily supported on the porous hydrogen separation layer (typically the surface layer) by simple immersion. Moreover, aggregation is suppressed also by the immersion, and the complex can be highly dispersed and uniformly supported on the outer surface and pores of the hydrogen separation layer.

  In a preferred embodiment of the method disclosed herein, the hydrogen separation layer of the porous body is composed of silica, and the solvent of the solution is an organic solvent. Silica has low water resistance, and its structure is changed by immersion in water, and there is a possibility that the hydrogen separation performance is lowered. In such a configuration, even if a silica hydrogen separation layer (for example, the entire porous body may be silica) is used as the porous body, the solvent of the solution containing the complex is an organic solvent. Is prevented. For this reason, the complex can be supported on the silica constituent portion without affecting the hydrogen permeability.

  In another preferred embodiment of the method disclosed herein, the surface layer of the porous body is silazane, and the solvent of the solution is water. Silazane has high water resistance unlike silica. For this reason, the metal can be easily supported on the hydrogen separation layer using water that is easy to handle.

How disclosed herein, the prior SL in the complex carrying process and then, a method including no sintering process.
The way this, complex reaction was allowed to bind to the pore inner wall and the outer surface of the porous hydrogen separation layer, does not perform the baking process. Therefore, the manufacturing cost is reduced. Furthermore, aggregation of the metal complex particles due to the firing treatment can be prevented, and a high hydrogen permeation rate can be maintained. Moreover, it is possible to use an organic porous material that can be burned out as the porous material.

  Moreover, this invention provides the hydrogen separation material obtained by one of the said methods as another side surface. Such a hydrogen separator has a high hydrogen permeation rate, and thus can efficiently separate hydrogen.

  Hereinafter, preferred embodiments of the present invention will be described. In addition, matters other than the matters specifically mentioned in the present specification (for example, the constitution of the porous body and the complex, the supporting method thereof, the constitution of the pretreatment method, etc.) and matters necessary for carrying out the present invention are as follows: It can be grasped as a design matter of a person skilled in the art based on the prior art in the field. The present invention can be carried out based on the contents disclosed in this specification and common technical knowledge in the field.

  The method for producing a hydrogen separation material of the present invention comprises a porous body having a hydrogen separation layer having a pore size that can selectively permeate hydrogen (typically a porous body having a hydrogen separation layer as a surface layer) and a predetermined metal. It is sufficient to support a complex having a central metal, and various structures can be applied for that purpose. Therefore, in the configuration other than carrying the complex, it can be carried out according to a conventionally known method for producing a hydrogen separator.

  The porous body used in the present invention may be composed of any conventionally known composition, and is not particularly limited. For example, various ceramic porous bodies are mentioned. Examples of the ceramic constituting the porous body include a porous body formed from silica, silazane, zirconia, α-alumina, zeolite, silicon nitride, or a composite or mixture thereof. An organic porous material such as polyamide or polyimide can also be used. In particular, the porous body to be adopted may be composed of a porous structure having a pore diameter that is a size that can selectively permeate hydrogen, but it improves mechanical strength and durability of the entire porous body. Therefore, it has a support layer having a relatively large pore size with high mechanical strength and durability (for example, corrosion resistance, heat resistance, acid resistance, moisture resistance) and a pore size of a size capable of selectively permeating hydrogen. A laminated structure having a hydrogen separation layer is preferable. The hydrogen separation layer is particularly preferably a surface layer. Moreover, in order to reduce the pore diameter gap between the support layer and the hydrogen separation layer, one or more intermediate layers may be provided. The composition of the support layer, the hydrogen separation layer (typically the surface layer), and optionally the intermediate layer may be the same or different.

  The support layer can have various porosity or average pore diameter depending on the purpose and application of the hydrogen separator, but preferably the porosity is about 20 to 60%, more preferably about 30 to 40%. The average pore diameter (based on the mercury intrusion method) is preferably about 4 to 1000 nm, more preferably about 4 to 100 nm. The thickness of the support layer is not particularly limited, but is preferably about 10 nm to 10,000 μm, more preferably about 10 nm to 2000 μm in order to maintain mechanical strength. The support layer is preferably a ceramic body, and α-alumina, silica, zirconia, and the like are particularly preferable because of their good mechanical strength and heat resistance.

The porosity of the hydrogen separation layer having a pore size that can selectively permeate hydrogen is not particularly limited, but preferably the porosity is about 10 to 50%, more preferably about 15 to 30%. is there. In particular, it is necessary that the pore size distribution is narrow and that many pores are selectively permeable to hydrogen, and the average pore size (based on the mercury intrusion method) is the molecular size of hydrogen molecules (about 0.1. 289 nm) is preferably about 0.3 to 10 nm, more preferably about 0.3 to 5 nm, still more preferably 0.3 to 1 nm, and particularly preferably 0.3 to 0, so as to be suitable for a selectively transmitting size. About 5 nm.
The porous hydrogen separation layer to be employed may be composed of any of the above-mentioned ceramics or organic ones, but silicon compounds such as silica and silazane, and organic compounds such as polyimide are preferred, and of these, silica is particularly preferred. It is preferable to use it because a pore size having an appropriate size can be obtained. The thickness of the hydrogen separation layer (membrane) is not particularly limited, but is preferably 10 to 1000 nm, and more preferably about 10 to 200 nm, because it is possible to obtain efficient and good hydrogen permeability.

In order to reduce the pore size gap between the support layer and the hydrogen separation layer (preferably the surface layer), an intermediate layer having an average pore size between the pore sizes of these layers can be used. Therefore, although the range of the average pore diameter of the intermediate layer varies depending on the average pore diameter of the support layer and the surface layer to be used, it can have an average pore diameter (based on the mercury intrusion method) of about 1 to 100 nm, for example. The intermediate layer is not particularly limited, and the ceramic or organic material can be appropriately selected and used. Preferably, α-alumina, γ-alumina having good mechanical strength and durability (heat resistance, etc.), Silica and / or zirconia can be mentioned. Of these, γ-alumina is particularly preferred. The thickness is not particularly limited, but is preferably 0.1 to 1000 μm, more preferably 1 to 500 μm, and particularly preferably about 1 to 100 μm for improving the mechanical strength.
Such an intermediate layer and a hydrogen separation layer can be formed on the porous body (base material constituting the support layer) by various conventionally known methods, and the methods are not limited. For example, as a method for forming an intermediate layer (for example, alumina intermediate layer), a sol (for example, boehmite sol) for forming the intermediate layer is dip coated on the support layer to form a gel film on the surface of the support layer, and this is dried. A sol-gel method for firing, or a method in which a support layer is dip-coated in a solution in which particles forming an intermediate layer (for example, alumina particles) are dispersed and supported on the surface of the support layer, followed by drying and firing. Can be mentioned.

Further, as a method for forming a hydrogen separation layer on a porous support layer (if the intermediate layer is formed if desired), for example, a sol for forming a hydrogen separation layer (for example, a silica layer) (for example, , Lower alkoxysilane) is dip-coated on the support layer (or intermediate layer if an intermediate layer is formed if desired) to form a gel film on the surface of the support layer (or intermediate layer), and the sol-gel is fired Law. Moreover, the method of forming the silica membrane which comprises a hydrogen separation membrane from polysilazane is mentioned. That is, for example, polysilazane can be obtained by reacting ammonia with a dihalosilane (R ₁ SiHX ₂ ) or a mixture of the dihalosilane and another dihalosilane (R ₂ R ₃ SiX ₂ ). Here, R ₁ , R ₂ , and R ₃ are different hydrocarbon groups or hydrogen, and X may be the same or different from each other, and may be a halogen atom such as fluorine, chlorine, Selected from the group consisting of bromine and iodine. Next, the resulting silazane oligomer is treated in the presence of a basic catalyst to dehydrogenate nitrogen atoms adjacent to the silicon atom to form polysilazane formed by dehydrogenative crosslinking of the silazane oligomers. A solution containing the polysilazane thus obtained or a commercially available polysilazane is applied to the support layer (if the intermediate layer is formed if desired, the intermediate layer) at a desired thickness (for example, 1 to 3 μm), A silica film can be formed by firing in a dry and air (oxidizing) atmosphere. Or the method of forming the silazane film | membrane which comprises a hydrogen separation film | membrane from polysilazane is mentioned. That is, a solution containing the polysilazane obtained as described above or a commercially available polysilazane is formed on the support layer (if the intermediate layer is formed if desired, the intermediate layer) at a desired thickness (for example, 1 to 3 μm). A silazane film can be formed by applying, baking and baking in an inert (non-oxidizing) atmosphere.

The shape of the porous body composed of the support layer, the hydrogen separation layer, and if necessary, the intermediate layer is not particularly limited, and can be appropriately selected depending on the application. For example, it can be a hollow fiber membrane, film or sheet. Among these, a hollow fiber membrane shape with high hydrogen separation efficiency is particularly preferable.
Further, the porous hydrogen separation layer may be subjected to a surface activation treatment before the complex supporting step, if desired. Such treatment is not particularly limited, and any conventionally known surface activation treatment can be performed. For example, heat treatment, laser treatment, plasma treatment, acid treatment, surfactant treatment and the like can be mentioned. Of these, plasma treatment is particularly preferred. The porous hydrogen separation layer can be subjected to surface activation treatment to adjust the time and amount of the complex supported.

The complex that can be used in the method of the present invention contains at least one kind of metal element of Group 5, Group 8, Group 9, and Group 10 of the periodic table of the long period type at least of the central metal. One. Examples of such a central metal include V, Nb, Ta, Fe, Ru, Os, Co, Rh, Ir, Ni, Pd, and Pt. Among these, V, Fe, Ru, Co, Rh, Ir, Ni, Pd, and Pt are preferable, Ru, Rh, Ni, Pd, and Pt are more preferable, Pd and Pt are more preferable, and Pd is particularly preferable.
In addition to the metals listed above or among the metals mentioned above, a complex having a catalytic metal as a central metal can be used to cause the complex to act as a reactive group such as a hydrogen generation reaction. . Alternatively, the durability of the hydrogen separation material can be improved by using a complex having a metal having some durability improving action as a central metal. For example, stability in a corrosive gas and water vapor atmosphere can be improved by using a complex having Ti, Zr, and / or Ta as a central metal.

Furthermore, as a ligand of a complex, any conventionally known ligand can be used and is not particularly limited. For example, acac (acetylacetonato), CH ₃ CO ₂ (acetate ion), bpy (bipyridine), phen (phenanthroline), ethylene, ethylenediamine, H ₂ O (aqua), NH ₃ (ammine), Cl (chloro), CO (carbonyl), NO (nitrosyl), PR ₃ (tertiary phosphine) and the like can be mentioned. Further, it may be a monodentate ligand, a polydentate ligand, or a bridging ligand. Of these, an acetate complex in which the ligand is an acetate ion and / or an acetylacetonato complex in which the ligand is acetylacetonate is preferable because the metal can be easily and finely supported on the hydrogen separation layer.

  Specific examples of complexes that can be suitably used are listed below. For example, the complex whose central metal is Co includes cobalt 2,4-pentadionate and cobalt acetate. Examples of the complex in which the central metal is Ni include nickel 2,4-pentadionate, nickel hexafluoropentadionate, and 1,3-bis (diphenylphosphino) propane nickel chloride. Examples of the complex whose central metal is Pd include palladium hexafluoropentadionate, palladium 2,4-pentadionate, and palladium acetate. Examples of the complex in which the central metal is Pt include platinum 2,4-pentadionate, dimethylplatinum cyclooctadiene, and platinum carbonylcyclovinylmethylsiloxane complex. Examples of the complex in which the central metal is Rh include rhodium 2,4-pentadionate, tris (dibutylsulfide) rhodium chloride, and tris (triphenylphosphine) rhodium chloride. Examples of the complex in which the central metal is Ru include ruthenium 2,4 monopentadionate, butofenatroline ruthenium, and tris (triphenylphosphine) ruthenium dichloride. Examples of the complex in which the central metal is V include vanadium 2,4-pentadionate. However, the present invention is not limited to these, and various conventionally known complexes can be used. Of these, cobalt 2,4-pentadionate, cobalt acetate, nickel 2,4-pentadionate, palladium 2,4-pentadionate, palladium acetate, platinum 2,4-pentadionate, rhodium 2,4 -Pentadionate, ruthenium 2,4 monopentadionate, vanadium 2,4-pentadionate, 1,3-bis (diphenylphosphino) propane nickel chloride, tris (triphenylphosphine) rhodium chloride are preferred. Further, cobalt 2,4-pentadionate, cobalt acetate, nickel 2,4-pentadionate, palladium 2,4-pentadionate, palladium acetate, platinum 2,4-pentadionate, rhodium 2,4-penta More preferred are dionate, ruthenium 2,4 pentapentanate, and vanadium 2,4-pentadionate.

Although it does not specifically limit as a mass average molecular weight of the complex to be used, Preferably about 100-700 can be used, Especially it is about 150-600.
As an applicable complex, those synthesized by a conventionally known production method can be used without particular limitation. For example, they can be easily obtained from Amax Co., Ltd. and N.E. A complex can be suitably used.

The amount of the complex supported on the hydrogen separation layer of the porous body is not particularly limited, and can be appropriately selected depending on the metal used, the average pore diameter of the hydrogen separation layer, and / or the hydrogen supply pressure. Preferably, the central metal per unit volume of the hydrogen separation layer is 1 to 60 mol / cm ³ , more preferably about 10 to 30 mol / cm ³ .
The means for supporting the complex on the porous hydrogen separation layer is not particularly limited, and any conventionally known means may be used. For example, immersion of the solution containing the complex, spray coating, or roll coating may be mentioned. In the case where the hydrogen separation layer is a surface layer of a porous body, it is particularly preferable that the hydrogen separation layer be immersed so that it can be uniformly supported on the entire surface layer and has good workability.
The treatment temperature in the supporting step is not particularly limited and can be appropriately selected, but is preferably room temperature to 200 ° C, more preferably room temperature to 150 ° C, and particularly preferably about room temperature to 100 ° C. By treating in such a temperature range, the complex can be supported uniformly and highly dispersed on the outer surface of the hydrogen separation layer and the inner wall surface of the pores, and undesirable behavior such as aggregation of metal complex particles is suppressed.
The solvent for the solution containing the complex may be any type of solvent, and examples thereof include water and organic solvents. The solvent can be appropriately selected according to the complex to be used and the material of the hydrogen separation layer. In particular, when the hydrogen separation layer is made of silica, it is preferable to apply an organic solvent because of its low water resistance. In addition, when the hydrogen separation layer is composed of silazane (that is, a compound mainly composed of SiN bonds, such as polysilazane), it is preferable to apply water with good workability.

In the method of the present invention, since the complex is used, the metal can be supported without firing the porous body during or after the supporting treatment step. Therefore, it is possible to obtain an unfired hydrogen separation material characterized in that the porous body is not fired during or after the complex loading step .

According to the present invention, a hydrogen separation material (membrane) having high hydrogen separation performance can be obtained as described above. In a preferred embodiment, the obtained hydrogen separating material has a hydrogen permeation rate of 1 × 10 ⁻⁷ mol · m ⁻² · s ⁻¹ · Pa ⁻¹ or more, particularly 5 × 10 ⁻⁷ mol · m at 150 ° C. ^-2 · s ^-1 · Pa ^-1 or higher, and further, high performance of 1 × 10 ^-6 mol · m ^-2 · s ^-1 · Pa ^-1 or higher can be obtained. Further, at 150 ° C., the hydrogen nitrogen permeation coefficient ratio (P _H2 / P _N2 ) can be as high as 50 or higher, particularly 100 or higher, and further 150 or higher. Furthermore, such high performance can be maintained for 100 hours or more, particularly 500 hours or more, and even 1000 hours or more.
According to the method disclosed herein, it is possible to produce a hydrogen separation material in which a predetermined metal excellent in hydrogen affinity is supported in a highly dispersed manner in a hydrogen separation layer having a predetermined average pore diameter that selectively permeates hydrogen. it can. For this reason, high hydrogen selective permeability and permeation speed can be realized. In addition, the obtained hydrogen separation material is excellent in durability (for example, heat resistance, moisture resistance, corrosion resistance) by selecting a porous material having excellent durability, and in a high-temperature atmosphere or a water vapor atmosphere. Deterioration is prevented, and high stability can be maintained. Therefore, it can be suitably applied to any application where hydrogen is required. For example, it can be used for hydrogen supply in fuel cells, electrolytic capacitors, and the like.

Several examples relating to the present invention will be described below, but the present invention is not intended to be limited to those shown in the examples.
(1) Manufacture of hydrogen separator <1-1> Manufacture of porous body (silica surface layer) As a support layer, α of a hollow fiber membrane having a porosity of 40% and an average pore diameter (based on mercury intrusion method) of 60 nm -Alumina was prepared.
A γ-alumina thin film was formed as an intermediate layer on the surface and in the pores. That is, for the formation of the γ-alumina thin film, boehmite sol prepared by hydrolyzing aluminum isopropoxide by a sol-gel method and then peptizing with an acid was used. A boehmite gel film was formed by dip coating (pulling speed 0.5 to 2.0 mm / sec) on the α-alumina support layer prepared above, and then dried overnight at room temperature to 60 ° C. The operation of baking at about 400 to 800 ° C. for about 5 to 10 hours was performed by repeating one or more times, preferably a plurality of times (here, twice). As a result, an intermediate layer having a porosity of 44% and an average pore diameter of 4 nm could be obtained. Alternatively, for the γ-alumina thin film (intermediate layer), γ-alumina particles (particle size 20 to 200 nm) are dispersed in water, and dip coating is applied to the α-alumina support layer (pulling speed 0.5 to 2.0 mm / sec). Then, after drying at room temperature to 60 ° C. overnight, the operation of baking at about 400 to 800 ° C. for about 5 to 10 hours can be formed by repeating once or more, generally a plurality of times.
Next, a silica thin film was formed as a hydrogen separation layer (surface layer) on the surface of the obtained intermediate layer. That is, the silica source was silicified on the surface and pores of the γ-alumina thin film. The supported silica clogged the surface layer of the membrane with a thin film. As a silica source, a lower alkoxysilane such as tetraethoxysilane is used, and this is hydrolyzed with an acid in ethanol by a sol-gel method to prepare a sol, and dip coating (with a pulling rate of 0.5-2. (0 mm / sec) and firing to form a silica thin film. Here, as long as it hydrolyzes and produces | generates a silica, you may use things other than tetra-lower alkoxysilane as a silica source. As a result, a silica surface layer (hydrogen separation layer) having a porosity of approximately 21% and an average pore diameter of 0.3 to 0.5 nm could be obtained.

<1-2> Surface Activation Treatment Plasma treatment was performed for 10 minutes on the porous body obtained in the production of <1> porous body.
<1-3> Complex support The hydrogen separation layer obtained as described in <1-1> above is immersed in the following complex solution heated to 80 ° C. for 12 hours, and the hydrogen separation layer (silica layer). Each supported a complex.
(Sample No. 1) Palladium 2,4-pentadionate (solvent: 1 mol% in toluene)
(Sample No. 2) Tris (triphenylphosphine) rhodium chloride (solvent: 1 mol% in toluene)
(Sample No. 3) 1,3-bis (diphenylphosphino) propane nickel chloride (solvent: 1 mol% in toluene)
On the other hand, the porous body subjected to the surface treatment as described in <1-2> was immersed in the following complex solution for 12 hours, and the hydrogen separation layer (silica layer) supported the respective complexes.
(Sample No. 4) Palladium 2,4-pentadionate (solvent: 1 mol% in toluene)
(Sample No. 5) Cobalt 2,4-pentadionate (solvent: 1 mol% in toluene)
(Sample No. 6) Vanadium 2,4-pentadionate (solvent: 1 mol% in toluene)
(Sample No. 7) Ruthenium 2,4-pentadionate (solvent: 1 mol% in toluene)
(Sample No. 8> palladium acetate (solvent: 1 mol% in acetone)
These obtained complexes were dried at 80 ° C. for 3 hours. All of them were supported on the outer surface of the hydrogen separation layer and the inner wall surface of the pore without heating or baking after the complex was supported. The central metal contained per unit volume of the hydrogen separation layer was about 20 mol / cm ³ . Moreover, since the solvent of the complex is an organic solvent, no change in the silica structure due to immersion was observed.

<2-1> Production of porous body (silica or silazane surface layer formed with silazane) (1) Except that polysilazane was used instead of tetraethoxysilane as a silica source, and the above <1- 1> A porous material was produced in the same manner as the production of the porous material. That is, a polysilazane solution obtained by dissolving a commercially available polysilazane in water was applied to a γ-alumina thin film at a thickness of 1 to 3 μm and dried at 60 ° C. for 3 hours to obtain a thin layer made of polysilazane. Subsequently, it was baked for 3 hours at 450 ° C. in an oxidizing atmosphere (air) to form a silica surface layer (hydrogen separation layer) having a porosity of 24% and an average pore diameter of 0.3 to 0.5 nm.
(2) Porous in the same manner as in the production of <1-1> porous body, except that polysilazane is used instead of tetraethoxysilane and a silazane thin film is formed instead of a silica thin film as a hydrogen separation layer (surface layer). The body was manufactured. That is, a polysilazane solution obtained by dissolving a commercially available polysilazane in water was applied to a γ-alumina thin film at a thickness of 1 to 3 μm and dried at 60 ° C. for 3 hours to obtain a thin layer made of polysilazane. Next, it was fired at 500 ° C. for 3 hours in a non-oxidizing atmosphere (N ₂ gas) to form a silazane surface layer (hydrogen separation layer) having a porosity of 35% and an average pore diameter of about 0.5 nm.
<2-2> Surface Activation Treatment Each of the hydrogen separation layers obtained in <2-1> was subjected to plasma treatment in the same manner as in the <1-2> surface activation treatment.

<2-3> Carrying of Complex (1) Silica surface layer or (2) Silazane surface layer subjected to surface treatment as in the above <2-2> was immersed in the following complex solution for 12 hours to produce hydrogen. Each of the separation layers supported a complex.
(Sample No. 9) Hydrogen separation layer: silica, complex: palladium 2,4-pentadionate (solvent: 1 mol% in toluene)
(Sample No. 10) Hydrogen separation layer: silazane, complex: tetraamminedipalladium (II) nitrate ([Pd (NH ₃ ) ₄ ] (NO ₃ ) ₂ ) (solvent: 1 mol% in water)
These complexes were dried at 80 ° C. for 3 hours. It was supported on the outer surface of the hydrogen separation layer and the inner wall surface of the pore without heating or baking after the complex was supported. The central metal contained per unit volume of the hydrogen separation layer was about 20 mol / cm ³ . Sample No. In No. 9, since the solvent of the complex was an organic solvent, no change was observed in the silica structure. Furthermore, sample no. In No. 10, no change in silazane structure due to immersion was observed even when the solvent of the complex was water.

<3> Comparative Example The porous body obtained in the production of <1-1> porous body is prepared as it is (without supporting a complex). It was set to 11.

(2) Hydrogen separation performance evaluation test The hydrogen separation performance of each of the hydrogen separation materials obtained as described above was evaluated.
The evaluation was performed by a hydrogen permeation test apparatus 1 as shown in FIG. That is, the hydrogen permeation test apparatus 1 mainly includes a gas supply unit 3, a separation unit 5, and a measurement unit 7. The gas supply unit 3 includes a hydrogen gas cylinder 9 and a nitrogen gas cylinder 11, and is connected to the separation unit 5 by a tube 14 having a valve 13. The separator 5 is provided with an electric furnace 15 on the outer periphery, and is configured to be heated to a predetermined temperature. In addition, the hollow fiber-shaped hydrogen separator 17 manufactured as described above is disposed at the center, and gas is supplied from the outer periphery of the hydrogen separator 17 and selectively transmits hydrogen from the inner periphery. It is configured to discharge. The inner periphery of the hydrogen separating material 17 is configured such that one end is sealed and the other end is connected to a gas chromatograph 18 provided in the measuring unit 7 and a tube 19 so that the permeation rate of discharged hydrogen and nitrogen can be measured. . Further, in order to measure the pressure difference between the inner peripheral side and the outer peripheral side of the hydrogen separating material 17, pressure gauges 21 and 23 are arranged in the gas supply side tube 14 and the hydrogen discharge side tube 19, respectively. In addition, a vacuum pump 25 capable of sucking gas is disposed between the tubes 14 and 19 in order to exhaust the gas inside the separation unit 5 before starting the next measurement after the measurement is completed.
While maintaining the separation unit 5 at a predetermined temperature by the electric furnace 15, hydrogen: nitrogen having a volume ratio of about 1: 1 is introduced from the gas supply unit 3 from the outer peripheral side of the hydrogen separator 17, The pressure difference from the inner peripheral side was set to 0.1 MPa. The flow rate of the gas that permeated through the hydrogen separating material 17 was measured by using the gas chromatograph 18 of the measuring unit 7, and the permeation rate for each gas was obtained. From the permeation rates for the respective gases, the permeation coefficient ratio (P _H2 / P _N2 ) and hydrogen permeation rate in the hydrogen-nitrogen separation of the hydrogen separating material 17 at 150 ° C. and 600 ° C. were determined. These results are shown in Table 1 below.

From these results, sample No. As compared with the sample No. 11, the sample NO. It was found that Nos. 1 to 10 maintained the same high hydrogen permeation rate even when a metal was supported on a hydrogen separation layer having a pore diameter that selectively permeates any hydrogen. It was also found that hydrogen permselectivity was improved by the metal loading. Furthermore, sample no. Sample No. 1 and 4 were found to maintain a high hydrogen permeation coefficient ratio and hydrogen permeation rate even at a high temperature of 600 ° C. This excellent hydrogen selective permeability was maintained for 1000 hours or more in the examples. On the other hand, Sample No. 11, when measured at 600 ° C. for 100 hours, both the permeability coefficient ratio and the hydrogen permeation rate are remarkably reduced (that is, the permeation coefficient ratio (P _H2 / P _N2 ) is 30 and the hydrogen permeation rate is 0.36 × 10 ^{− 6} mol · m ⁻² · s ⁻¹ · Pa ⁻¹ ), the silica thin film was densified, and it was found that the stability at high temperatures was poor. Therefore, it was found that the samples of the examples were excellent in high temperature stability.
In particular, sample No. 1 in which an acetylacetonato complex or acetate complex of Pd is supported on a silica thin film. 1, 4, and 8 all realize a high hydrogen permeation coefficient ratio of 150 or more and a high hydrogen permeation rate of 1.0 × 10 ⁻⁶ mol · m ⁻² · s ⁻¹ · Pa ⁻¹ or more. I was able to. Sample No. 1 in which Pd acetylacetonate complex is supported on a silazane thin film is also shown. 10 was able to realize a high hydrogen permeation rate of 4.0 × 10 ⁻⁶ mol · m ⁻² · s ⁻¹ · Pa ⁻¹ or higher.

  The preferred embodiments of the present invention have been described in detail above, but these are only examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the above-described embodiments. The technical elements described in this specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Moreover, the technique illustrated in this specification or the drawings achieves a plurality of objects at the same time, and has technical usefulness by achieving one of the objects.

It is a schematic diagram explaining the apparatus which evaluates hydrogen separation performance.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Hydrogen permeation test apparatus 3 ... Gas supply part 5 ... Separation part 7 ... Measurement part 9 ... Hydrogen gas cylinder 11 ... Nitrogen gas cylinder 15 ... Electric furnace 17 ... Hydrogen separation material 18 ... Gas chromatograph 21, 23 ... Pressure gauge 25 ... Vacuum pump

Claims (8)

A method for producing a hydrogen separator, comprising:
A step of preparing a porous body having a hydrogen separation layer having a pore size that can selectively permeate hydrogen, at least part of the porous body;
The porous hydrogen separation layer carries a complex having at least one metal element selected from the group consisting of elements of Group 5, 8, 9, and 10 of the long-period periodic table as at least one central metal. A process of
Only including,
Here, no firing treatment is included during and after the complex supporting step,
A hydrogen separation material, wherein the complex is supported on an outer surface of the hydrogen separation layer and an inner wall surface of the pore ;
Method for producing a.   The method of claim 1, wherein the complex comprises Pd as a central metal.   The method according to claim 1 or 2, wherein, in the complex supporting step, the porous body is immersed in a solution containing the complex.   The method according to claim 3, wherein the hydrogen separation layer of the porous body is composed of silica, and the solvent of the solution is an organic solvent.   The method according to claim 3, wherein the porous hydrogen separation layer is made of silazane, and the solvent of the solution is water.   The method according to any one of claims 1 to 5, wherein the complex is an acetate complex and / or an acetylacetonato complex. The method according to claim 1, wherein at least the hydrogen separation layer is subjected to a surface activation treatment before the complex supporting step. The surface activation treatments include plasma treatment, claim 7 Symbol mounting method.

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