JP2007237074A - Hydrogen permeable separation membrane exhibiting excellent hydrogen permeable separation capability - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydrogen permeable separation membrane exhibiting excellent hydrogen permeable separation capability. <P>SOLUTION: The hydrogen permeable separation membrane is made of a high strength Ni-Ti-Nb alloy with a composition containing Nb: 10-47% by atom, Ti: 20-52% by atom, and balance Ni and inevitable impurities (containing Ni: 20-48% by atom), made to be a refining heat treated material of a cast foil material of the composition with a thickness of 0.07 mm or thinner by a roll quenching method, and having an alloy structure consisting of a basis metal containing Ni-Ti (Nb) intermetallic compound, which is formed by forming a solid solution of Nb by replacing a portion of Ti in a Ni-Ti intermetallic compound, and fine particles of a Nb-based solid solution alloy formed by forming solid solution of Nb with Ni and Ti. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention is composed of a Ni—Ti—Nb alloy having a high mechanical strength, and thus enables a thin film with a thickness of 0.07 mm (70 μm) or less. The present invention relates to a hydrogen permeation separation thin film that can significantly improve performance.

In recent years, high-purity hydrogen gas has attracted attention as a fuel gas for energy systems such as hydrogen fuel cells and hydrogen gas turbines, and this high-purity hydrogen gas is a mixed gas or liquefied natural gas obtained by electrolyzing water. As shown in the schematic explanatory view of FIG. 3, for example, the outer peripheral portion is reinforced with a frame body made of Ni, for example, as shown in the schematic explanatory diagram of FIG. Thickness capable of only hydrogen permeation: 0.1 to 3 mm hydrogen permeable separation membrane partitioned into left and right side chambers, hydrogen-containing source gas introduction pipe and exhaust gas extraction pipe in left side chamber, right side chamber Is a high-purity hydrogen purifier having a structure in which a reaction chamber made of high-purity hydrogen gas is attached, for example, made of stainless steel, in the center, and the reaction chamber is heated to 200 to 300 ° C. Than tube The internal pressure of the right side chamber where the high-purity hydrogen gas separated through the hydrogen permeation separation membrane is introduced is kept at 0.1 MPa, while the internal pressure of the left side chamber where the hydrogen-containing source gas exists is introduced. It is known that it is produced by separating and refining high-purity hydrogen gas through the hydrogen permeable separation membrane under the condition that is maintained at 0.2 to 0.5 MPa.
Further, the hydrogen permeable separation membrane performs a selective hydrogen transfer through the hydrogen permeable separation membrane, for example, a chemical reaction such as a hydrocarbon steam reforming process or a hydrogenation / dehydrogenation process such as a benzene-cyclohexane reaction. It is well known that it is widely used in processes.

Furthermore, the hydrogen permeable separation membrane is
(A) Ni: 25-45 atomic%, Ti: 26-50 atomic%,
And the remainder is composed of Nb and inevitable impurities (however, Nb: 11 to 48 atom%),
(B) Thickness cut out from the casting ingot by electric discharge machining: 0.1 to 3 mm of cast thin plate material, and as shown in the structural photograph (magnification: 2500 times) by a scanning electron microscope in FIG. An eutectic structure of a solid solution NbTi phase and a NiTi phase solid solution of Nb is used as a base material, and an alloy structure in which primary crystal NbTi phases are dispersed and distributed on the base material,
It is also known that it is composed of a Ni—Ti—Nb alloy having the component composition (a) and the alloy structure (b).
JP 2005-232491 A

  On the other hand, the demand for high performance of various chemical reaction apparatuses including the above-described hydrogen high-purity purification apparatus is extremely strong, and accordingly, the hydrogen permeation separation membrane used as a structural member of the apparatus is much higher. It is required to have hydrogen permeation separation performance, and generally, in the case of the hydrogen permeation separation membrane, it is known that the hydrogen permeation separation performance is improved as the film thickness is reduced. From the above, the development relating to the strengthening of the Ni—Ti—Nb alloy constituting the hydrogen permeable separation membrane has been actively carried out. However, in the conventional hydrogen permeable separation membrane, the Ni—Ti—Nb constituting this has been developed. Since the mechanical strength of the alloy is not sufficient, it cannot be thinned to a thickness of 0.1 mm or less, so that satisfactory hydrogen permeation separation performance cannot be improved at present.

In view of the above, the present inventors have made it possible to reduce the thickness of the hydrogen permeable separation membrane, which is a structural member, in order to improve the performance of the various chemical reaction devices described above. As a result of conducting research while focusing on increasing the strength of the Ni-Ti-Nb alloy constituting the hydrogen permeable separation membrane, the hydrogen permeable separation membrane is expressed in atomic% (hereinafter,% indicates atomic%).
Nb: 10 to 47%, Ti: 20 to 52%,
The remaining alloy is specified as a component composition consisting of Ni and inevitable impurities (Ni: 20 to 48%), and the molten alloy is cast into a thickness of 0.07 mm or less by a roll quenching method. When a tempering heat treatment is applied to the cast foil material in an inert gas atmosphere or a vacuum atmosphere for the purpose of preventing oxidation under a condition of heating and holding at a temperature of 300 to 1100 ° C. for a predetermined time, The resulting tempered heat treatment material contains solid solution in a state where Nb replaces a part of Ti in the Ni-Ti intermetallic compound as shown in the structural photograph (magnification: 2500 times) by a scanning electron microscope in FIG. The fine particles of the Nb-based solid solution alloy in which Ni and Ti are dissolved in Nb (shown in black in FIG. 1) on the substrate made of the Ni—Ti (Nb) intermetallic compound (shown in black in FIG. 1) Distributed) The Ni-Ti-Nb alloy with this alloy structure has an extremely high mechanical strength. Therefore, in practical use as a hydrogen permeable separation membrane, the film thickness should be 0.07 mm or less. As a result, research results have been obtained that hydrogen permeation and separation performance will be improved over a long period of time.

This invention was made based on the above research results,
(A) Nb: 10 to 47%, Ti: 20 to 52%,
Component composition consisting of Ni and inevitable impurities (however, Ni: 20-48% content),
(B) Thickness by roll quenching method: Ni--containing a solid solution in a state where a part of Ti in a Ni-Ti intermetallic compound is substituted by Nb as a tempered heat treatment material of a cast foil material of 0.07 mm or less An alloy structure in which fine particles of an Nb-based solid solution alloy in which Ni and Ti are solid-dissolved in Nb are dispersed and distributed on a substrate made of a Ti (Nb) intermetallic compound,
It is characterized by a hydrogen permeation separation thin film that exhibits excellent hydrogen permeation separation performance and is composed of a high-strength Ni—Ti—Nb alloy having the component composition (a) and the alloy structure (b). .

Next, the reason why the composition of the Ni—Ti—Nb alloy constituting the hydrogen permeation separation thin film of the present invention is limited as described above will be described.
(A) Nb
As described above, the Nb component contains a part of Ti in the Ni—Ti intermetallic compound in a substituted form to form a Ni—Ti (Nb) intermetallic compound constituting the substrate, In addition to improving hydrogen permeation separation performance, an Nb-based solid solution alloy containing Ni and Ti as a solid solution is formed and dispersed and distributed as fine particles in the substrate, thereby exhibiting excellent hydrogen permeation separation performance. However, if the content is less than 10%, the desired excellent hydrogen permeation separation performance cannot be exhibited even if the thickness of the thin film is reduced to 0.07 mm or less, while if the content exceeds 47%. Since the alloy structure cannot be secured stably, the content is determined to be 10 to 47%.

(B) Ti and Ni
For the Ti and Ni components, a Ni—Ti (Nb) intermetallic compound constituting the substrate is formed to improve the mechanical strength of the thin film, thereby enabling practical use with a thickness of 0.07 mm or less. In addition, it has the effect of increasing the mechanical strength of the Nb-based solid solution alloy dispersed and distributed as fine grains in the substrate, but the content of either Ti or Ni is Ti: 20% If Ni is less than 20%, the desired mechanical strength cannot be ensured for the thin film, making practical use at a thickness of 0.07 mm or less difficult, while containing either Ti or Ni Even if the amount exceeds Ti: 52% and Ni: 48%, the decrease in hydrogen permeation separation performance is unavoidable. Therefore, the contents are defined as Ti: 20-52% and Ni: 20-48%, respectively. It was.

  The hydrogen permeation separation thin film of the present invention can be thinned to a thickness of 0.07 mm or less by the Ni—Ti (Nb) intermetallic compound of the base having high mechanical strength, and hydrogen permeation separation by this thinning is possible. When the Nb-based solid solution alloy that is uniformly distributed as fine particles on the substrate exhibits excellent hydrogen permeation separation performance, it is used in various chemical reactors. Thus, excellent hydrogen permeation separation performance is exhibited over a long period of time.

  Next, the hydrogen permeation separation thin film of the present invention will be specifically described with reference to examples.

Purity: 99.9% high purity Nb shot material, 99.9% high purity Ni shot material, and 99.5% high purity Ti sponge material were used. Blended at the indicated ratio, arc melted in a high purity Ar atmosphere to form an ingot, and this ingot is cut into 20 mm squares, and the bottom has a length: 20 mm x width: 0.3 mm. Of a water-cooled copper roll that is charged into a graphite crucible having a slit formed therein and re-melted in a high-frequency induction heating furnace in a reduced pressure argon atmosphere of 0.06 MPa, and the molten metal is rotated at a roll speed of 20 m / sec from the slit. Each surface was sprayed with an injection pressure of 0.05 MPa, and each had a planar dimension of length: 20 m × width: 20 mm, but the thicknesses were the average thicknesses shown in Table 1 (average values at five arbitrary locations). Ni -A cast foil material of Ti-Nb alloy is formed, and then this is charged into a vacuum furnace and kept at a predetermined temperature within a range of 300 to 1100 ° C for 5 hours in a vacuum of 10 ^-2 Pa or less. Heat treatment is performed under conditions of post furnace cooling, and after the heat treatment, the hydrogen permeation separation thin film of the present invention (hereinafter referred to as the present hydrogen permeation thin film) 1 to 2 is cut out into a plane dimension of width: 20 mm × length: 60 mm. 24 were produced respectively.

  For the purpose of comparison, as a raw material, a high purity Nb shot material having a purity of 99.9%, a high purity Ni shot material having a purity of 99.9%, and a high purity Ti sponge material having a purity of 99.5% are used. Each of these raw materials was blended in the proportions shown in Table 2, arc-melted in a high-purity Ar atmosphere, cast, and Ni—Ti—Nb alloy ingot having a diameter of 80 mm × thickness of 10 mm. From this ingot, both have a plane dimension of width: 20 mm × length: 60 mm by electric discharge machining, and the thicknesses are the average thicknesses shown in Table 2 (average values at five arbitrary locations). The conventional hydrogen permeation separation membranes (hereinafter referred to as conventional hydrogen permeation membranes) 1 to 10 each made of a cast cut thin plate material were produced by cutting the thin plate material.

  The resulting hydrogen permeable thin films 1 to 24 of the present invention and the conventional hydrogen permeable membranes 1 to 10 were measured for their component compositions using an energy dispersive X-ray fluorescence spectrometer. The analysis value was substantially the same as the composition of the composition, and the structure was observed using a scanning electron microscope and an X-ray diffractometer. As a result, the present invention hydrogen permeable thin films 1 to 24 show the present invention in FIG. As shown in the alloy structure of the hydrogen permeable thin film 19, all of the Ni—Ti intermetallic compound containing Ni—Ti (Nb) intermetallic compound containing Ni—Ti (Nb) intermetallic compound in a state where a part of Ti is substituted by Nb FIG. 2 shows an alloy structure in which fine particles of an Nb-based solid solution alloy in which Ni and Ti are solid-dissolved are dispersed and distributed. On the other hand, in the conventional hydrogen permeable films 1 to 10, the alloy structure of the conventional hydrogen permeable film 8 is shown in FIG. As shown Both the eutectic structure of the NiTi phase solid solution of NbTi phase and Nb was dissolved the Ni and the matrix, the primary crystal NbTi phase showed alloy structure, dispersed distributed in this matrix.

  Next, a Pd thin film having a thickness of 0.1 μm is deposited on both surfaces of the hydrogen permeable thin films 1 to 24 of the present invention and the conventional hydrogen permeable films 1 to 10 by sputtering (in this case, formed by electroplating). Each of which is sandwiched from two sides by two copper reinforcing frames having dimensions of 20 mm × vertical outer dimensions: 60 mm × frame width: 5 mm × frame thickness: 0.5 mm. In a state where the permeable membrane is fixed to the reinforcing frame, it is installed in a reaction chamber of a hydrogen permeation evaluation apparatus having the same structure as the hydrogen high-purity purification apparatus having the structure shown in FIG. 3, and the reaction chamber is heated to 300 ° C. Then, hydrogen gas was introduced into the left chamber of the reaction chamber, first, the internal pressure of the left chamber and the right chamber of the reaction chamber was set to 0.1 MPa, and then the internal pressure of the right chamber was maintained at 0.1 MPa, The internal pressure of the left chamber was 0.1 MPa At a rate of 5 minutes, the hydrogen permeable thin films 1 to 7 of the present invention and the conventional hydrogen permeable films 1 and 2 are up to 0.7 MPa, and the hydrogen permeable thin films of the present invention 8 to 24 and the conventional hydrogen permeable thin films 3 to 9 are 0.5 MPa. Up to 0.3 MPa for the conventional hydrogen permeable membrane 10, and when maintained for 1 hour under these conditions, the permeated hydrogen gas flow rate (shown in Tables 1 and 2 as the initial permeated hydrogen flow rate) is gas. Measured with a flow meter and further increased under these conditions, that is, the internal pressure of the right side chamber was increased to 0.1 MPa, and the internal pressure of the left side chamber was increased to 0.7 MPa, 0.5 MPa, and 0.3 MPa, respectively, and held for 1 hour. From the time point, when it continued for 20 hours under the same conditions, the flow rate of the permeated hydrogen gas (shown as the late permeate hydrogen flow rate in Tables 1 and 2) was measured, and the measurement results are shown in Tables 1 and 2 .

As shown in Tables 1 and 2, each of the hydrogen permeable thin films 1 to 24 of the present invention has a high mechanical strength ensured by the base Ni—Ti (Nb) intermetallic compound, and has a thickness of 0.07 mm or less. The Nb-based solid solution alloy that is dispersed and distributed as fine particles on the substrate exhibits excellent hydrogen permeation separation performance together with excellent hydrogen permeation separation performance over a long period of time. To demonstrate
In contrast to excellent durability (service life), the conventional hydrogen permeable membranes 1 to 10 cannot be made to have a film thickness of 0.1 mm or less from the viewpoint of mechanical strength. It is clear that the separation performance is low.

  As described above, the hydrogen permeation separation thin film of the present invention is composed of a Ni—Ti—Nb alloy having high mechanical strength, and can be thinned to a thickness of 0.07 mm or less. At this time, since the excellent hydrogen permeation separation performance is demonstrated over a long period of time, the hydrogen permeation separation membrane can satisfactorily meet the demand for high performance of various chemical reactors used as structural members. is there.

It is a structure | tissue photograph (magnification: 2500 times) of the Ni-Ti-Nb alloy which comprises this invention hydrogen permeable thin film 19 by the scanning electron microscope. It is the structure | tissue photograph (magnification: 2500 times) of the Ni-Ti-Nb alloy which comprises the conventional hydrogen permeable film 8 by the scanning electron microscope. It is a schematic explanatory drawing which illustrates a hydrogen high purity refiner.

Claims (1)

(A) Nb: 10 to 47 atomic%, Ti: 20 to 52 atomic%,
And the remainder is composed of Ni and inevitable impurities (however, Ni: 20 to 48 atomic%),
(B) Thickness by roll quenching method: Ni--containing a solid solution in a state where a part of Ti in a Ni-Ti intermetallic compound is substituted by Nb as a tempered heat treatment material of a cast foil material of 0.07 mm or less An alloy structure in which fine particles of an Nb-based solid solution alloy in which Ni and Ti are solid-dissolved in Nb are dispersed and distributed on a substrate made of a Ti (Nb) intermetallic compound,
A hydrogen permeation separation thin film exhibiting excellent hydrogen permeation separation performance, characterized by comprising a high-strength Ni—Ti—Nb alloy having the component composition (a) and the alloy structure (b).

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