KR102023600B1 - Separation membrane, hydrogen separation membrane including separation membrane and device including hydrogen separation membrane - Google Patents

Abstract

Provided are a separator comprising at least one Group 5 element, Fe and Al, and a hydrogen separator and a hydrogen separator including the same. The alloy has a crystal structure of a body centered cubic structure formed by the Group 5 elements, Fe, and Al elements together.

Description

Separation membrane, a hydrogen separation membrane comprising the same, and a hydrogen separation apparatus including the hydrogen separation membrane TECHNICAL FIELD

A separator, a hydrogen separator including the same, and a hydrogen separator including the hydrogen separator.

BACKGROUND OF THE INVENTION Pd-based metals have been widely known as a membrane for selectively separating only hydrogen gas from a gas mixture containing hydrogen gas. The Pd-based metal forms a face-centered cubic structure (FCC), which allows selective separation of hydrogen through hydrogen dissolution and diffusion through space in a unit cell. However, the high cost of the Pd-based metal and the difficulty in improving the permeability make it a limiting factor for commercialization.

Accordingly, there is an increasing need for a hydrogen-competitive membrane having a competitive price while having excellent hydrogen permeation performance similar to that of a Pd-based metal.

In one embodiment, it is to provide a separator that is excellent in hydrogen permeability properties, can suppress hydrogen embrittlement breakdown, and can be produced at low cost.

Another embodiment is to provide a hydrogen separation membrane comprising the separation membrane.

In another embodiment, to provide a hydrogen separation device including the hydrogen separation membrane.

In one embodiment, a separator including an alloy of a Group 5 element, iron (Fe), and aluminum (Al), wherein the alloy includes a crystal structure of a body centered cubic structure (BCC).

The Group 5 element may be vanadium (V), niobium (Nb), or a combination of V and Nb .

Specifically, the Group 5 element is V.

In the separator, the content of Fe in the alloy is less than about 20 atomic%, and the content of Al is less than about 30 atomic%.

Specifically, the content of Fe in the alloy is about 1 atomic% to about 15 atomic%, and the content of Al is about 3 atomic% to about 25 atomic%.

More specifically, the content of Fe in the alloy is about 3 atomic% to about 10 atomic%, and the content of Al is about 5 atomic% to about 20 atomic%.

In the separator, at least about 80% by volume of the alloy may form a crystal structure having a body centered cubic structure.

Specifically, about 85% by volume or more of the alloy may form a crystal structure of the body centered cubic structure.

The separator may have a non-porous dense membrane structure having a porosity of less than about 1% by volume.

Specifically, the separator has a porosity of less than 0.5% by volume, more specifically, the porosity of the separator is 0% by volume.

The alloy may further comprise one or more additional metals selected from the group comprising Ni, Co, Mn, Cu, and combinations thereof.

The amount of the added metal is about 0.1 atomic% to about 10 atomic%.

More specifically, the content of the added metal is about 1 atomic% to about 5 atomic%.

The separator may have a thickness of about 1 μm to about 500 μm.

According to another embodiment, a hydrogen separation membrane including the separation membrane according to the embodiment is provided.

The hydrogen separation membrane may have a hydrogen solubility (H / M) measured at about 0.1 to about 1 MPa hydrogen pressure and about 400 ° C., about 0.01 to about 0.5.

Specifically, the hydrogen solubility (H / M) measured at about 0.7 MPa (about 7 bar) hydrogen pressure and about 400 ° C. with respect to the hydrogen separation membrane may be about 0.1 to about 0.4.

Hydrogen permeability (hydrogen permeability) of the hydrogen separation membrane can be about 1.0 × 10 ^-8 to about ^{15.0 × 10 -8 mol / m *} s * Pa 1/2 at about 400 ℃ conditions.

A catalyst layer may be further included on one side or both sides of the separator.

The catalyst layer may include at least one selected from the group consisting of Pd, Pt, Ni, Ru, Ir, and combinations thereof, and at least one alloy selected from the group consisting of Cu, Ag, Au, Rh, and combinations thereof. Can be.

According to another embodiment of the present invention, the hydrogen comprises a hydrogen separation membrane according to the embodiment, a chamber having a supply means for supplying a mixed gas containing hydrogen gas, and a discharge chamber including a means for discharging separated hydrogen gas A separation device is provided, wherein one surface of the hydrogen separation membrane is in contact with the chamber and the other surface is in contact with the discharge chamber.

In one embodiment, the hydrogen separation membrane is formed in a tubular shape, a cylindrical chamber partition wall larger than the diameter of the tubular hydrogen separation membrane is formed on the outside of the hydrogen separation membrane, the space between the chamber partition and the hydrogen separation membrane as a chamber The tubular hydrogen separator may be formed as a discharge chamber through which hydrogen is discharged.

The separator has excellent hydrogen permeability, high resistance to hydrogen embrittlement fracture, and can be manufactured at low cost.

1 is a schematic view showing the structure of a crystal lattice that can be formed in the alloy in the separator according to an embodiment of the present invention.
2 is a schematic diagram showing a mechanism in which hydrogen gas is separated by passing through a hydrogen separation membrane according to an embodiment of the present invention.
FIG. 3 (a) is a graph showing the results of the pressure-compositionn-isotherms (PCT) evaluation in the case of alloying by adding various kinds of transition metals to the vanadium (V) element.
FIG. 3 (b) shows the softness maintaining effect of Al, in which Fe and Al are added together with varying amounts of V and alloyed by adding Al or V in varying amounts, respectively, in pure V This is a graph compared with.
FIG. 4 (a) is a graph showing the tendency of increasing the alloy hardness when Fe, Al, or Fe and Al are added to V together with increasing amounts of alloying, respectively.
FIG. 4 (b) shows a hydrogen separation membrane alloyed by adding 10 atomic% of Fe, Ni, Al, Al and Fe (AlFe), Al and Ni (AlNi), and Ni and Fe (NiFe) in total amounts to V; It is a graph comparing the hardness.
FIG. 5 is an XRD evaluation graph measured at room temperature after alloying pure V, and Al, Fe, or both Al and Fe with varying contents, respectively.
FIG. 6 shows pure V, V-10Fe alloy with 10 atomic% Fe added to V, V-10Al alloy with 10 atomic% Al added to V, and 5 atomic% Al and 5 atomic% Fe to V. The hydrogen permeability of the added V-5Fe-5Al alloy is measured in the temperature range of 573K to 673K.
FIG. 7 shows a hydrogen separation membrane made of pure V, a separator made of a V-10Fe alloy added with 10 atomic% Fe to V, a separator made of a V-10Al alloy added with 10 atomic% Al to V, and V The hydrogen permeability (hydrogen permeability) according to the temperature change is measured while cooling the hydrogen separation membrane made of a V-5Fe-5Al alloy to which 5 atomic% Al and 5 atomic% Fe are added.
8 shows a hydrogen separation membrane made of pure V, a hydrogen separation membrane made of pure Pd, a hydrogen separation membrane made of a V-10Fe alloy containing 10 atomic% Fe added to V, and V- having 10 atomic% Al added to V. It is a graph measuring hydrogen diffusivity according to temperature change of a hydrogen separation membrane made of a 10Al alloy and a hydrogen separation membrane made of a V-5Fe-5Al alloy having 5 atomic% Al and 5 atomic% Fe added to V. FIG.
9 is a schematic diagram of a hydrogen separation apparatus according to an embodiment.
10 is a schematic view of a hydrogen separation device including a tubular separator according to another embodiment.

Hereinafter, an embodiment will be described in detail so that a person skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention.

The present invention may be embodied in many different forms and is described with reference to the drawings as necessary and is not limited to the embodiments described herein. Since the size and thickness of each component shown in the drawings of the present specification are arbitrarily shown for convenience of description, the present invention is not necessarily limited to the illustrated. In addition, the size and thickness of each component shown in the drawings are arbitrarily exaggerated for convenience of description, the present invention is not necessarily limited to the illustrated.

According to one embodiment of the present invention, an alloy comprising at least one Group 5 element, iron, and aluminum, wherein at least 80% by volume of the alloy is a crystal structure of a body centered cubic structure (BCC) It provides a separator for forming.

 The separator may be used as a separator capable of selectively separating a specific gas.

The separator may be a hydrogen separator.

Recently, hydrogen is attracting attention as a clean energy. Separators for selectively separating hydrogen from the hydrogen-containing gas is known various metal / metal alloys, silica / zeolite ceramics, metal ceramic composites (cermet), carbon-based, or polymer membranes. Among them, Pd-based alloy separators are typically used commercially (Chem. Rev., 107, 4078-4110 (2007)). However, in the case of Pd-based alloys, Pd itself is expensive as a noble metal, and even in the case of the alloy-based alloy, hydrogen separation performance is improved by only 2 to 3 times. Pd-Ag23, Pd-Cu40 and the like are known as representative Pd-based alloys (Platinum Metals Rev., 21, 44-50 (1977)).

Research on Group 5 metals (Vanadium (V), Niobium (Nb), Tantalum (Ta)) as an alternative candidate of the conventional Pd-based alloy separator has been actively conducted. These metals have a higher hydrogen affinity than Pd and excellent hydrogen-containing ability, and have excellent hydrogen diffusion characteristics through small lattice of body centered cubic (BCC), and are generally 10 to 100 times better than Pd-based hydrogen. Permeation performance (J. Membr. Sci., 362, 12-28 (2010)).

However, in spite of the excellent permeability of these metals, however, under high temperature and high pressure operating conditions, these metals are brittle due to hydride (hydride phase) formation, that is, cracks due to hydrogen embrittlement. There is a disadvantage that occurs easily.

In one embodiment of the present invention to solve the hydrogen embrittlement problem through the alloying of the Group 5 metal, in particular to produce a separator capable of producing a hydrogen permeability excellent and low cost.

The separator according to the embodiment of the present invention includes the alloy, and is equivalent to the separator manufactured using an inexpensive metal such as Fe and Al, but using an expensive metal such as Pd, Pt, or Ir. Level of excellent hydrogen permeation properties. In addition, it is possible to maintain low hydrogen solubility while using Group 5 metals, thus suppressing hydrogen embrittlement breakdown and maintaining high hydrogen permeability. In addition, since the separator includes an alloy that forms a crystal structure having a body centered cubic structure of 80% by volume or more, there is no problem of deterioration of performance due to amorphous crystallization as compared to an amorphous metal separator, and thus durability may be advantageous. In addition, since the separator ensures the same level of ductility as the pure Group 5 metal even at room temperature, it is possible to produce a thin membrane having a large area even by a cold rolling method which is a low cost process.

In order to find a low-cost alloy metal candidate group capable of reducing hydrogen content in pure Group 5 metals such as vanadium (V), experiments were conducted in which 5 transition% of various transition metals were added to V. As a result, it was found that Fe and Al reduce hydrogen solubility (see FIG. 3 (a)). In the case of Cr, Mo, and W, alloying with V was good, but there was little effect of reducing the hydrogen solubility of V metal. As a result, it was found that when the same amount of alloying metal, Fe lowers the hydrogen solubility of V metal than Ni.

Metals such as Fe and Ni, which reduce hydrogen solubility, have the property of reducing the lattice constant of the parent metal, resulting in a solid solution hardening effect and an alloy brittle. In this case, when volume expansion occurs during hydrogen solid solution, brittle fracture easily occurs in the metal. If the ductility of the metal itself decreases and becomes brittle, the critical concentration of hydrogen solubility that causes brittle fracture is lowered.

Therefore, among the metals having the effect of reducing the hydrogen solubility, a metal that can maintain the ductility of the Group 5 metal well was confirmed. As shown in Fig. 4 (a), V (Vanadium), which is a Group 5 element, As a result of adding different concentrations, it was found that Al did not significantly increase the hardness of the alloy even when 5 atomic% and 10 atomic% were added. In contrast, in the case of Fe, which is a metal capable of reducing hydrogen solubility, it was found that the hardness increased considerably when 5 atomic% and 10 atomic% were alloyed with V metal, respectively. Therefore, it can be seen that Al is suitable as a metal capable of maintaining the ductility of the alloy while reducing the hydrogen solubility.

Thus, alloys V-5Al and V-10Al added 5 atomic% and 10 atomic% Al to pure V, alloys V-5Fe and V-10Fe added 5 atomic% and 10 atomic% Fe respectively to V, And alloys V-2.5Fe-2.5Al having 2.5 atomic% of Al and Fe added to V, and alloys V-5Fe-5Al having 5 atomic% of Al and Fe added to V, respectively. They measured pressure-composition-isotherms with pure V. As a result, as shown in FIG. 3 (b), V-2.5Fe-2.5Al obtained by alloying Fe and Al together by V by 2.5 atomic%, and V- which alloyed Fe and Al together by 5 atomic% by V It was confirmed that the hydrogen solubility of 5Fe-5Al was significantly lower than that of Fe or Al alloyed with V alone or pure V metal.

4 (b) shows an alloy in which 10 atomic% Fe, Ni, and Al are added to vanadium (V) and 10 atomic% in total of 5 atomic% of Al and Fe, respectively (FIG. 4 ( b) AlFe), an alloy containing 10 atomic% of Al and Ni in total of 10 atomic% each (shown as AlNi in FIG. 4 (b)), and 10 atomic% of Ni and Fe in total of 5 atomic% It is the result of measuring the hardness of the added alloy (indicated by NiFe in FIG. 4 (b)). From this graph, it can be seen that when Al is added to V alone, the ductility remains the lowest. However, considering the mutual combination with Fe, Ni, or Al metal for reducing hydrogen solubility, the AlFe alloy has the lowest ductility. It can be seen that.

That is, as shown in FIG. 3 (b), when Fe and Al are alloyed together with Group 5 element V, hydrogen solubility of the alloy is maintained at the lowest, and as shown in FIG. 4 (b), Group 5 When Fe and Al were alloyed together with the element V, it was confirmed that the ductility of the alloy was also kept low.

Therefore, in one embodiment of the present invention, a group 5 element, and an alloy containing Fe and Al together, 80% by volume or more of these alloys provides a separator comprising a BCC structure. The BCC structure in the alloy of the separator is schematically shown in FIG. 1, each metal component contained in a lattice structure is shown.

The Group 5 element may be vanadium (V), niobium (Nb), or a combination of V and Nb.

Specifically, the Group 5 element may be vanadium (V).

V has a smaller metal lattice than Nb, so that hydrogen solubility can be lowered compared to Nb under the same conditions.

The content of each element forming the alloy is based on the number of atoms forming the total alloy, Fe is less than 20 atomic%, specifically 1 atomic% to 15 atomic%, more specifically 3 atomic% to 10 atomic% Al may be present in less than 30 atomic%, specifically 3 to 25 atomic%, more specifically 5 to 20 atomic%. When in the content range, the alloy can maintain the ductility of the alloy while the hydrogen solubility is low to inhibit hydrogen embrittlement.

The separator may further include one or more additional metals selected from the group including Ni, Co, Mn, Cu, and combinations thereof in the alloy.

The added metal may be included in the range of about 0.1 atomic% to about 10 atomic% based on the total number of atoms of the alloy.

The separator, as the ductility of the alloy is maintained, It can be easily prepared to have a thickness of about 1 to about 500 ㎛ using a low-cost process such as cold rolling, the method of manufacturing the separator is not limited to the cold rolling method.

According to another embodiment of the present invention, a hydrogen separation membrane including the separation membrane is provided. The hydrogen separator is a separator that selectively separates only hydrogen gas from a gas mixture containing hydrogen gas, and has a high hydrogen permeation characteristic by including a crystal structure of a body centered cubic structure that can easily diffuse hydrogen. . As a result, the hydrogen separation membrane is capable of high purity hydrogen separation. For example, the hydrogen separation membrane may be 80% by volume or more of the alloy crystal structure of the body-centered cubic structure. The separator having a high level of crystal structure as described above may be suitable for use as a hydrogen separator.

The hydrogen separation membrane is steam reforming, coal gasification, water gas shift reaction (WGS). It can be applied to the technical field for selectively permeating and separating only H ₂ gas from the gas containing H ₂ , CO ₂ , CO, etc. generated through the reaction. For example, the present invention can be applied to fields such as high purity hydrogen generator, fuel cell hydrogen regenerator, gas separation hydrogen separation membrane, and H ₂ / CO ₂ separation membrane.

The separated hydrogen may be used for electricity generation as a clean energy source, or may be used as a chemical raw material (NH ₄ , olefin, etc.) or for petroleum refining. On the other hand, since the gas remaining after the removal of hydrogen is a gas composed of a high concentration of CO ₂ components, such a CO ₂ rich gas (CO ₂ rich gas) may be selectively collected and stored to use for the purpose of removing CO ₂ .

The hydrogen separation membrane adsorbs hydrogen gas (H ₂ ) among various gases including hydrogen, and the adsorbed hydrogen gas (H ₂ ) is dissociated with hydrogen atoms (H) at the surface of the hydrogen separation membrane. The dissociated hydrogen atom (H) is permeated through the separator. The hydrogen atom (H) is dissolved (or dissolved) through the tetrahedral or octahedral interstitial space of the unit cell of the separator and is also diffused. Permeation (MD Dolan, J. membrane science 362, 12-28 (2010)). The hydrogen atom (H) that has passed through the membrane is recombined again to form hydrogen gas (H ₂ ), and then the hydrogen separation membrane is detached and separated.

FIG. 1 is a schematic diagram showing types of crystal lattice that the separator may include, and illustrates a crystal lattice that an alloy including at least one Group 5 element, Fe, and Al may be formed. Group 5 elements form a body-centered cubic structure. In FIG. 1, the vanadium (V) atom, which is a group 5 element, is located at various vertices of the body-centered cubic structure, and the alloyed atom Al is located at the body-center of the body-centered cubic structure. The case where it is located on one vertex of a cubic structure is shown. That is, the separator has a crystal structure of a body centered cubic structure formed by the Group 5 elements, Fe, and Al together.

When the alloy of the separator further includes the above-described additional metals, these metals may form a body-centered cubic structure together with the Group 5 elements, Fe, and Al.

The separator may be formed as a nonporous dense membrane structure having a porosity of less than about 1% by volume and a porosity of about 0% by volume. By having such a structure, only the substance to be separated can be selectively permeated and separated. When the separation membrane is applied as a hydrogen separation membrane, it is formed in a dense membrane structure to selectively separate only hydrogen by permeation.

Membranes composed of pure Group 5 elements form metal hydrides during permeation of hydrogen, which can result in 'hydrogen embrittlement'. When external stress is applied to such embrittlement, hydrogen embrittlement is destroyed. (hydrogen embrittlement fracture) occurs. In order to suppress hydrogen embrittlement destruction, hydrogen solubility must be lowered. The separation membrane is alloyed with Fe, which is a metal capable of lowering the hydrogen solubility of the Group 5 element, and is also composed of pure Group 5 elements or only Fe or Al alone, due to the ductile retention function of Al. Compared to the alloy-containing separator in the element, it is possible to significantly lower the hydrogen solubility and hydrogen embrittlement fracture. When Fe and Al are alloyed to form the crystal structure as shown in Fig. 1, the binding energy of the hydrogen atom and the Group 5 element is changed to reduce the hydrogen solubility. Hydrogen solubility means the concentration of hydrogen dissolved in the metal and is calculated by the molar ratio (H / M) of hydrogen (H) and metal (M) dissolved in water.

For example, for a V-Fe-Al alloy each containing about 5 atomic% of Fe and Al elements, the hydrogen solid solution energy (heat of H solution) in the high hydrogen concentration region (molar ratio of H / Nb is about 0.5). ) Is calculated using the Density Functional Theory (DFT), which is about -0.25 eV, which is lower in absolute hydrogen as compared to about -0.4 eV for pure Nb.

As described above, the separation membrane lowers the hydrogen solubility by adding Fe and Al to the Group 5 element and alloying the same. In addition, such a separation membrane can provide a hydrogen separation membrane having excellent hydrogen separation characteristics at low cost without using expensive metals such as Pb and Nb, by using inexpensive metals such as Fe and Al.

By changing the content of each element forming the alloy of the separator, it is possible to design the separator according to the characteristics of the membrane to be applied. Specifically, the separator may contain less than about 20 atomic% Fe, specifically about 1 atomic% to about 15 atomic%, and more specifically, about 3 to about 10 atomic%. The separator may contain less than about 30 atomic% Al, specifically about 3 atomic% to about 25 atomic%, and more specifically, about 5 atomic% to about 20 atomic%. Separation membrane containing Fe and Al element in the above content range is excellent in hydrogen permeability, but the hydrogen brittle fracture is reduced, durability is improved, and also can be manufactured at low cost, it is useful to be used as a hydrogen separation membrane.

The separator may be an alloy further comprising other additional metals in addition to the Group 5 elements, Al, and Fe. For example, the separator may be a four-component alloy or a five-component alloy. The additional metal may be one selected from the group comprising Ni, Co, Mn, Cu, and combinations thereof. As the additional metal is further included, hydrogen solubility of the separator may be further lowered and ductility may be increased.

The additional metal may also form a body-centered cubic structure together with the Group 5 elements, Fe and Al in the alloy. The alloy further comprising the additional metal may form some intermetallic compound, but mostly forms a crystal structure of a body centered cubic structure, such that the volume of the alloy may be 80% even in a separator made of an alloy further containing the additional metal. More than% may be composed of the crystal structure of the body-centered cubic structure.

When the separator further includes the additional metal, the additional metal may be included in the range of about 0.1 to about 10 atomic% based on the total number of atoms of the metal in the separator.

As described above, the hydrogen separation membrane prepared using the separator has a low hydrogen solubility, and specifically, the hydrogen solubility measured at about 0.1 to about 1 MPa hydrogen pressure and about 400 ° C. is about 0.01 to about 0.5, and more specifically about 0.05 to about 0.45. More specifically, the hydrogen solubility measured at about 0.7 MPa (about 7 bar) hydrogen pressure and about 400 ° C. conditions may be about 0.1 to about 0.4.

Hydrogen separator prepared using the separator prepared as described above has excellent hydrogen permeability. Hydrogen permeability can be calculated by the following equation.

[Equation 1]

Permeability: Permeability, J: Flux, L: Membrane Thickness, P _{H2 , in} : Supply hydrogen pressure, P _{H2, out} : permeate hydrogen pressure.

Hydrogen permeability (hydrogen permeability) of the separator may be about 1.0 × 10 ^-8 to about ^{15.0 × 10 -8 mol / m *} s * Pa 1/2 at 400 ℃ conditions, specifically from about 1.2 × 10 ^-8 to about ^{12.0 × 10 -8 mol / m *} s * Pa may be ^1/2, more specifically, about 1.5 × 10 ^-8 to about ^{10.0 × 10 -8 mol / m *} s * Pa may be ^1/2 .

The separator may have a thickness of about 1 to about 500 μm, specifically about 10 to about 100 μm. When the separator has a thickness in the above range, it may have a permeability suitable for application to the separator. The thickness may be the thickness of the hydrogen separation membrane 23 of FIG. 9 or the thickness of the hydrogen separation membrane 33 tube of FIG. 9.

The separator may be prepared according to a known alloy production method, it is not limited to that method. For example, in order to melt each metal uniformly by arc melting, induction melting, etc., and to produce a film having a desired thickness, hot rolling, cold rolling, and deposition are performed. The separator may be manufactured by a plating process.

In the case of the separator according to the embodiment, it is particularly excellent in ductility can be prepared using a low cost process such as cold rolling.

The hydrogen separation membrane may be a catalyst layer formed on one side or both sides of the separation membrane. FIG. 2 illustrates a hydrogen separation membrane 10 in which a catalyst layer 12 is formed on both surfaces of the separation membrane 11, and schematically illustrates a mechanism through which hydrogen gas H ₂ passes through the hydrogen separation membrane. As described above, since the permeation of hydrogen through the hydrogen separation membrane 10 is made by the hydrogen atom, dissociation of the hydrogen molecule (H ₂ ) to the hydrogen atom (H) is necessary. The catalyst layer 12 may act as a catalyst to help dissociation of such hydrogen molecules. Hydrogen selectively permeated through the hydrogen separation membrane 10 needs to be recombined again with hydrogen molecules, and such recombination may be accelerated by the catalyst layer 12.

As described above, the catalyst layer 12 may be made of a material capable of catalyzing a reaction of dissociating hydrogen molecules or recombining hydrogen molecules on the surface of the hydrogen separation membrane 10, and specifically, At least one selected from the group consisting of Pd, Pt, Ru, Ir, and combinations thereof, and at least one alloy selected from the group consisting of Cu, Ag, Au, Rh, and combinations thereof.

The thickness of the catalyst layer 12 may be, for example, about 20 to about 1,000 nm, specifically about 50 to about 500 nm. When the catalyst layer 12 has a thickness in the above range, the catalyst layer 12 may function smoothly without inhibiting the permeability of the entire hydrogen separation membrane 10.

In another embodiment of the present invention, the hydrogen separation membrane comprises a hydrogen separation membrane according to the embodiment, a chamber having a supply means for supplying a mixed gas including hydrogen gas, and a discharge chamber including a discharge means for separating hydrogen gas. Provide the device.

The hydrogen separation membrane is positioned such that one surface of the hydrogen separation membrane is in contact with the chamber and the other surface is in contact with the discharge chamber.

9 is a schematic diagram schematically showing the hydrogen separation device 20 according to one embodiment. When the mixed gas containing the hydrogen gas is introduced into the chamber 22 through the supply means 21 of the mixed gas containing the hydrogen gas, only the hydrogen gas in the mixed gas is selectively discharged through the hydrogen separation membrane 23. Separated by). The separated hydrogen gas may be recovered through the discharge means 25. The hydrogen separation device 20 may further include a means 26 for recovering the remaining gas from which the hydrogen gas is separated. Since the hydrogen separation device 20 is illustrated in a simplified form for convenience of description, it may further include additional components according to the use.

10 is a schematic diagram showing another embodiment in which the hydrogen separation device 30 is formed in a tubular shape. The hydrogen separation device 30 includes a tubular hydrogen separation membrane 33, and a cylindrical chamber partition wall 36 larger than the diameter of the tubular hydrogen separation membrane is formed outside of the hydrogen separation membrane 33 to form the chamber. A space between the partition 36 and the hydrogen separation membrane is formed as the chamber 32, and the inside of the tubular hydrogen separation membrane is formed as the discharge chamber 34 through which hydrogen is discharged. The chamber 32 may further include a supply means (not shown) of a mixed gas including hydrogen gas and a recovery means (not shown) of remaining gas from which hydrogen gas is separated. In addition, a discharge means (not shown) for discharging the separated hydrogen gas in the discharge chamber 34 may be further provided.

In another embodiment, in the case of including a tubular hydrogen separation membrane 33, a mixed gas is supplied into the tubular hydrogen separation membrane 33 as opposed to the case of FIG. 10, and hydrogen in the mixed gas is tubular hydrogen. Passing through the separator 33 may be separated to the outside of the tubular hydrogen separation membrane 33 may be formed to discharge hydrogen. That is, the inside of the hydrogen separation membrane 33 is formed as a chamber through which the mixed gas is supplied, and the outside of the hydrogen separation membrane 33 is formed as the discharge chamber through which hydrogen is discharged.

The following presents specific embodiments of the present invention. However, the embodiments described below are merely for illustrating or explaining the present invention in detail, and thus the present invention should not be limited thereto.

( Example )

Production Example  1: Preparation of Hydrogen Separator

Based on the vanadium (V) element, various metal elements (Al, Cr, Fe, Mo, W, Ti, and Zr) are added thereto in various content ratios, and uniformly dissolved by the arc melting method to proceed with alloying. By doing so, a hydrogen separation membrane having a thickness of 400 μm is prepared. In addition, as a comparative example, only a vanadium (V) or palladium (Pd) element is dissolved in the same manner to prepare a hydrogen separation membrane.

Specifically, the elements are quantified to prepare a material in an arc melter, and then the material is made into a high vacuum (2 × 10 ⁻⁵ torr or less) to completely remove oxygen. Thereafter, Ar gas is injected to make anti-oxidation conditions, and then the current is increased to melt the material, and then naturally cooled in an arc melter. The manufactured Ingot is made to have a thickness of 400 μm, and then heat-treated in a high vacuum furnace to remove defects such as surface contaminants, internal stresses, and dislocations. Thereafter, Pd is coated on both surfaces of the membrane to a thickness of 150 nm to prepare a hydrogen separation membrane for measuring hydrogen permeability.

Experimental Example  1: search for alloys with reduced hydrogen solubility

The effect of reducing the hydrogen solubility when added to the Group 5 metals was examined through pressure-composition-isotherms (PCT).

For the alloy hydrogen separation membrane prepared by adding various transition metals (Cr, Fe, Mo, W, Ti, Zr) to each of the vanadium (V) metals prepared in Preparation Example 1 by 5 atomic%, the JIS H7201 standard was used. Accordingly, the hydrogen solubility was evaluated according to the hydrogen pressure at 400 ℃. Evaluation was carried out using a Sievert-type pressure-composition-isotherms (PCT) facility, the results are shown in Figure 3 (a).

As shown in FIG. 3 (a), in the case of Cr, Mo, and W, there was little effect of reducing the hydrogen solubility. On the other hand Fe was found to reduce the hydrogen solubility in proportion to the amount added.

Experimental Example  2: alloy search with alloy ductility retention effect

Vickers hardness of the alloy separator was measured to indirectly identify a metal that can maintain the ductility of the vanadium (V) metal when added. In general, it is known that as the hardness of the metal increases, brittleness and ductility decrease. In order to measure the hardness of the vanadium (V) alloy, unlike in Preparation Example 1, one side of the alloy sample prepared in the form of water droplets by arc melting was polished using sandpaper. After smoothly polishing the surface with 600 fine sandpaper, the hardness was measured using a hardness tester capable of applying a load of 1 kg.

Referring to FIG. 4 (a), it can be seen that the hardness of vanadium (V) is increased the least when Al is added. It can be seen that the ductility of the alloy formed when Al is the most excellent. In the case of Fe, even when the addition of 5 atomic% shows a high hardness value increase it can be seen that the ductility of the alloy quickly decreases.

4 (b) shows ductility when alloying by adding 10 atomic% of Fe, Ni, Al, Al and Fe (AlFe), Al and Ni (AlNi), and Ni and Fe (NiFe), respectively, in total in V; The change is graphed. When 10 atomic% Al is added to the vanadium (V) metal, the ductility retention effect is the best, and the alloy (AlFe) having Al 5 atomic% and Fe 5 atomic% is excellent in ductility. In the case of Al metal, it is known that the addition of 5 atomic% or more does not reduce the solid solution due to lattice expansion. Therefore, rather than adding 10 atomic% of Al to V in order to reduce the solidity and maintain ductility, it is more advantageous to make a three-component alloy V-5Fe-5Al containing 5 atomic% of Al and 5 atomic% of Fe. do. This is also demonstrated from the result of Fig. 4 (a). That is, in the case of a three-component alloy prepared by adding Fe and Al to V together, unlike the case where Fe is added alone, even if added until the sum of the Fe and Al content is 10 atomic%, it is still cold It can be seen that the ductility of the rollable degree is maintained.

Experimental Example  3: hydrogen solubility evaluation

According to the results of Experimental Example 1 and Experimental Example 2, alloys V-5Al or V-5Fe added with 5 atomic percent or 10 atomic percent to vanadium (V), respectively, and Fe to vanadium (V), respectively Alloy V-5Fe or V-10Fe added at 5 atomic% or 10 atomic%, Alloy V-5Fe-5Al added 5 atomic% Al with 5 atomic% Fe to vanadium (V), and Vanadium (V) Alloy V-2.5Fe-2.5Al with 2.5 atomic% Al and 2.5 atomic% Fe was added thereto, and these were measured for PCT (pressure-hydrogen solubility-temperature) at 400 ° C with pure vanadium (V) separator. . PCT measurement method is as described in Experimental Example 1.

As a result, as shown in Fig. 3 (b), V-2.5Fe-2.5Al and V-5Fe-5Al in which Fe and Al were alloyed together with the Group 5 element V, respectively, Fe or Al independently It was confirmed that the hydrogen solubility was significantly lower than that of the alloy alloyed with or the pure V metal.

Under conditions of 400 ° C., 7 bar (0.7 MPa), when 5 atomic% Al and 5 atomic% Fe are added together, and when 2.5 atomic% Al and 2.5 atomic% Fe are added together, the hydrogen solubility (H / M) were all less than 0.25. It is known that hydrogen embrittlement fracture of vanadium (V) metal is suppressed when the hydrogen solubility degree (H / M) is 0.25 or less in the conditions of 400 degreeC and 7 bar (0.7 MPa).

Experimental Example  4: Body-centered cubic  Maintenance confirmation

Even if Al is added to increase the ductility of the alloy, the body centered cubic (bcc) lattice structure of vanadium (V) must be well maintained for good hydrogen diffusion characteristics.

Room temperature for hydrogen separation membranes (pure V, V-5Fe, V-10Fe, V-5Al, V-10Al, V-2.5Fe-2.5Al, and V-5Fe-5Al) prepared according to Preparation Example 1 X-ray diffraction analysis (XRD) was carried out at (about 25 ° C.) to confirm the crystal structure, and the results are shown in FIG. 5.

As shown in FIG. 5, it can be seen that all the metals maintain the bcc lattice structure well. It can be seen that Al increases the lattice size of V and Fe decreases the lattice size of V. It can be seen that when adding 5 atomic% Al and 5 atomic% Fe, and adding 2.5 atomic% Al and 2.5 atomic% Fe, the effects of lattice expansion and contraction are canceled out to be similar to the lattice size of pure V. .

Experimental Example  5: hydrogen permeation characteristics evaluation

For a hydrogen separation membrane made of pure water V, V-10Fe, V-10Al, and V-5Fe-5Al prepared according to the method of Preparation Example 1, hydrogen permeability is calculated from Equation 1 below.

[Equation 1]

Where Flux (J) is the hydrogen permeation rate per unit area, L is the thickness of the hydrogen separation membrane, and ((P _{H2 , in} ) ^1/2- (P _{H2 , out} ) ^1/2 ) is the hydrogen input of the hydrogen separation membrane This is the difference between the square root of the partial pressure of hydrogen and the output.

FIG. 6 is a graph measuring hydrogen permeability of the hydrogen separation membrane in a temperature range of 573K to 673K according to Equation 1 above.

6, the Al-containing alloy hydrogen separation membrane was 1.0 x 10 ^-7 mol m ^-1 s ^-1 Pa ^{-0 at 673K.} It can be seen that it has a very high hydrogen permeability of more than ^five . However, it can be seen that the V-5Fe-Al alloy hydrogen separator including 5 atomic% Fe instead of 5 atomic% Al also has almost the same hydrogen permeability as the V-10Al alloy hydrogen separator. However, as shown in FIG. 3 (a), the hydrogen solubility of the V-5Fe-Al alloy at 673K is similar to that of V-10Fe alloy. In conclusion, the hydrogen permeability results, it is thought that the co-addition of Fe and Al has a complex effect on the hydrogen solubility and the hydrogen diffusivity of the hydrogen separation membrane, the result is believed to show the above hydrogen permeability results.

8 is a graph measuring hydrogen diffusivity of the hydrogen separation membrane over 573K to 773K. Hydrogen diffusivity coefficients are described by K. Yamakawa et al., J. Alloys Compd. 321 (2001) determined by the Time-lag method as described in 17. As can be seen from FIG. 8, all alloy hydrogen separation membranes exhibit lower hydrogen permeability than pure V separators. However, it can be seen that the V-5Fe-5Al alloy hydrogen separator has a much higher hydrogen diffusion coefficient than the V-10Al alloy hydrogen separator or the V-10Fe alloy hydrogen separator. As described above, the hydrogen permeability results shown in FIG. 6 can be seen as a composite result of the hydrogen diffusivity shown in FIG. 8 and the hydrogen solubility shown in FIG. 3 (a).

Experimental Example  6: hydrogen Embrittlement  Destruction rating

The hydrogen permeability of the hydrogen separation membrane made of pure V, V-10Fe, V-10Al, and V-5Fe-5Al prepared according to the method of Preparation Example 1 was measured at 350 ° C. while cooling to room temperature, and the hydrogen permeability was measured. Is shown in FIG. 7. To this end, the hydrogen separation membrane is previously maintained at 7 bar hydrogen pressure and 400 ° C. for 4 hours, and then the hydrogen permeability of the hydrogen separation membrane is measured while cooling to room temperature at a temperature reduction rate of 5 ° C./min .

As can be seen from FIG. 7, the hydrogen separation membrane made of pure V has a membrane breakdown (permeability increase) due to hydrogen embrittlement fracture at around 275 ° C., whereas in the case of an alloy hydrogen separation membrane made of V-5Fe-5Al, It is shown that brittle fracture occurs at low temperatures below < RTI ID = 0.0 > This reduction in the embrittlement temperature of the hydrogen separator shows that the alloy may be exposed to a long term hydrogen environment at high temperatures.

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the scope of the invention.

1: Group 5 element 2: Al atom
3: Fe atom
10: hydrogen separation membrane 11: separation membrane
12: catalyst layer 20, 30: hydrogen separation device
21: supply means of a mixed gas containing hydrogen gas
22, 32: chamber 23, 33: hydrogen separation membrane
24, 34: discharge chamber 26: recovery means
25: means for discharging separated hydrogen gas
36: chamber bulkhead

Claims (20)

An alloy of a Group 5 element, iron (Fe) and aluminum (Al), wherein the content of Al in the alloy is 5 atomic% or less, the sum of the contents of Fe and Al is 10 atomic% or less, and the alloy A separator comprising a crystal structure of a body centered cubic structure (BCC). The separator of claim 1, wherein the Group 5 element is V (vanadium), Nb (niobium), or a combination of V (vanadium) and Nb (niobium). The separation membrane of claim 1, wherein the Group 5 element is V. 3. The separator of claim 1, wherein the Group 5 element is V, the Fe content is 5 atomic%, the Al content is 5 atomic%, and the V content is 90 atomic%. The separation membrane of claim 1, wherein the Group 5 element is V, the Fe content of the alloy is 2.5 atomic%, the Al content is 2.5 atomic%, and the V content is 95 atomic%. delete The separator of claim 1, wherein at least 80% by volume of the alloy forms a crystal structure having a body centered cubic structure. The separator of claim 1, wherein at least 90% by volume of the alloy forms a crystal structure having a body centered cubic structure. The separator of claim 1, wherein the porosity is less than 1% by volume. The separator of claim 1, wherein the alloy is an alloy further comprising one or more additional metals selected from the group comprising Cu, Ni, Co, Mn, and combinations thereof. The separator of claim 10, wherein the added metal has a content of 0.1 atomic% to 10 atomic%. The separator of claim 1, wherein the separator has a thickness of 1 to 500 μm. A hydrogen separation membrane comprising the separation membrane of any one of claims 1 to 5 and 7 to 12. The hydrogen separation membrane of claim 13, wherein the hydrogen solubility is measured at a hydrogen pressure of 0.1 to 1 MPa and 400 ° C. to 0.01 to 0.5. The hydrogen separation membrane of claim 13, wherein the hydrogen solubility is measured at a hydrogen pressure of 0.7 MPa and 400 ° C. In claim 13 wherein the hydrogen permeability measured at 400 ℃ (hydrogen permeability) is 1.0 × 10 ^-8 to about ^{15.0 × 10 -8 mol / m *} s * Pa 1/2 of a hydrogen separation membrane. The hydrogen separation membrane of claim 13, further comprising a catalyst layer on one or both surfaces of the separation membrane. 18. The method of claim 17, wherein the catalyst layer is at least one selected from the group consisting of Pd, Pt, Ru, Ir, and combinations thereof, and at least one alloy selected from the group consisting of Cu, Ag, Au, Rh, and combinations thereof. Hydrogen separator comprising a. A hydrogen separation membrane according to claim 13;
A chamber having means for supplying a mixed gas containing hydrogen gas; And
A discharge chamber including discharge means for separating hydrogen gas,
One surface of the hydrogen separation membrane is in contact with the chamber, the other surface is in contact with the discharge chamber. The method of claim 19,
The hydrogen separation membrane is formed in a tubular shape,
A cylindrical chamber partition wall larger than the diameter of the tubular hydrogen separation membrane is formed outside the hydrogen separation membrane,
A space between the chamber partition wall and the hydrogen separation membrane is formed as a chamber, and the tubular hydrogen separation membrane is formed as a discharge chamber through which hydrogen is discharged.
Hydrogen separation device.

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