Abstract:
A hydrogen permeable membrane which has an excellent high-temperature amorphous stability and a long lifetime under high-temperature heating operation and which can be miniaturized for use in a high-performance hydrogen purifier. The hydrogen permeable membrane is made of a non-crystalline nickel-zirconium alloy or zirconium-nickel alloy composed of  44  to  75  atom % of nickel or zirconium; and  0.2  to  16  atom % of aluminum,  0.2  to  12  atom % of vanadium and/or niobium, or  0.2  to  12  atom % of niobium and  0.1  to  10  atom % of phosphorus (provided that the combined amount of niobium and phosphorus is not more than  18  atom %); with the balance being zirconium or nickel and unavoidable impurities.

Description:
CROSS-REFERENCE TO PRIOR APPLICATION 
   This is a U.S. National Phase application under 35 U.S.C. §371 of International Patent Application No. PCT/JP2003/014829, filed Nov. 20, 2003, and claims the benefit of Japanese Patent Application Nos. 2002-336216, filed Nov. 20, 2002; 2002-336217, filed Nov. 20, 2002; 2002-336218, filed Nov. 20, 2002; 2002-336219, filed Nov. 20, 2002; 2002-336220, filed Nov. 20, 2002 and 2002-336221, filed Nov. 20, 2002, all of which are incorporated by reference herein. The International Application was published in Japanese on Jun. 3, 2004 as WO 2004/045751 A1 under PCT Article 21(2). 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a hydrogen permeable membrane which has an excellent high-temperature amorphous stability, i.e., the quality of stably maintaining non-crystallinity for a long period of time when held in a high-temperature state, and which when used as a hydrogen permeable membrane in an apparatus such as a high-performance hydrogen purifier thus makes it possible to carry out a high-temperature heating operation that enhances the productivity of such a high-performance hydrogen purifier. 
   2. Description of the Related Art 
   “Green energy” has attracted much attention in recent years as a way to counteract such phenomena as atmospheric pollution and global warming. In particular, energy systems which use hydrogen gas (one type of green energy) as the fuel, such as hydrogen fuel cells and hydrogen gas turbines, are currently under active investigation. 
   The high-purity hydrogen gas used as the fuel gas in these energy systems is produced from a hydrogen-containing feed gas such as a mixed gas obtained by electrolyzing water or a mixed gas obtained by steam reforming liquefied natural gas (LNG). Such production is typically carried out using a high-performance hydrogen purifier like that shown schematically in  FIG. 1  which is divided into a left-hand chamber and a right-hand chamber by a hydrogen permeable membrane that is made of a material permeable only to hydrogen and is reinforced at the periphery with a frame made of nickel or the like. A hydrogen-containing feed gas inlet and a bleed gas outlet are attached to the left-hand chamber, a high-purity hydrogen gas outlet is attached to the right-hand chamber, and a reaction chamber made of a material such as stainless steel is provided at the center. The feed gas is passed through the hydrogen permeable membrane with the reaction chamber heated to 200 to 300° C., thereby producing high-purity hydrogen gas by separative purification. 
   Hydrogen permeable membranes of this type which are made of non-crystalline nickel-zirconium or zirconium-nickel alloys are known. Processes for fabricating such membranes are known to include a liquid quenching process in which an alloy melt of a given composition is sprayed onto the surface of, for example, a rapidly rotating copper roll to effect solidification to a film thickness of 5 to 500 μm (e.g., see JP-A 2000-256002). 
   To enhance productivity, there is a trend among such high-performance hydrogen purifiers toward operation under high-temperature heating. In prior-art high-performance hydrogen purifiers which use hydrogen permeable membranes made of non-crystalline nickel-zirconium alloys, during operation at a high heating temperature above 300° C., the hydrogen permeable membrane which exhibits a high hydrogen-separating and permeating ability owing to its non-crystallinity is readily subject to localized crystallization. In the areas that have crystallized, the hydrogen permeating and purifying ability of the membrane markedly declines, as a result of which the passage through the membrane and admixture of impurity gases other than hydrogen cannot be avoided. Accordingly, such hydrogen permeable membranes have a relatively short service life. 
   There also exists a strong need for an even higher performance and a smaller size than has hitherto been achieved in high-performance hydrogen purifiers. This need has created in turn a strong desire for hydrogen permeable membranes endowed with a greater hydrogen-separating and permeating ability. 
   SUMMARY OF THE INVENTION 
   In light of the above, we have conducted investigations focused particularly on the above-described prior-art hydrogen permeable membranes made of non-crystalline nickel-zirconium and zirconium-nickel alloys which would enable operation of the above-described high-performance hydrogen purifiers under high-temperature heating. 
   The present invention provides a hydrogen permeable membrane made of a non-crystalline nickel-zirconium alloy composed of 44 to 75 atom % of nickel and 0.2 to 16 atom % of aluminum, with the balance being zirconium and unavoidable impurities; or made of a non-crystalline zirconium-nickel alloy composed of 44 to 75 atom % of zirconium and 0.2 to 16 atom % of aluminum, with the balance being nickel and unavoidable impurities. If the alloy used is a non-crystalline zirconium-nickel alloy, the nickel content is preferably not more than 43 atom %. 
   The aluminum included as an alloying element markedly improves the high-temperature amorphous stability of this hydrogen permeable membrane. Even in a high-temperature state above 300° C., crystallization is substantially suppressed, enabling the non-crystalline structure to be maintained over a long period of time. The use of such a membrane in a high-performance hydrogen purifier, for example, enables this high-temperature heating operation to be carried out, as a result of which productivity can be further enhanced. 
   The invention also provides a hydrogen permeable membrane made of a non-crystalline nickel-zirconium alloy composed of 44 to 75 atom % of nickel and 0.2 to 12 atom % of vanadium and/or niobium, with the balance being zirconium and unavoidable impurities; or made of a non-crystalline zirconium-nickel alloy composed of 44 to 75 atom % of zirconium and 0.2 to 12 atom % of vanadium and/or niobium, with the balance being nickel and unavoidable impurities. If the alloy used is a non-crystalline zirconium-nickel alloy, the nickel content is preferably not more than 43 atom %. 
   The vanadium and/or niobium included as an alloying element markedly improves the hydrogen-separating and permeating ability of this hydrogen permeable membrane. Accordingly, employing this membrane in a high-performance hydrogen purifier contributes to higher performance and downsizing of the purifier. 
   The invention additionally provides a hydrogen permeable membrane made of a non-crystalline nickel-zirconium alloy composed of 44 to 75 atom % of nickel, 0.2 to 12 atom % of niobium, and 0.1 to 10 atom % of phosphorus, provided the combined amount of niobium and phosphorus is not more than 18 atom %, with the balance being zirconium and unavoidable impurities; or made of a non-crystalline zirconium-nickel alloy composed of 44 to 75 atom % of zirconium, 0.2 to 12 atom % of niobium, and 0.1 to 10 atom % of phosphorus, provided the combined amount of niobium and phosphorus is not more than 18 atom %, with the balance being nickel and unavoidable impurities. If the alloy used is a non-crystalline zirconium-nickel alloy, the nickel content is preferably not more than 43 atom %. 
   The niobium included as an alloying element greatly enhances the hydrogen-separating and permeating ability of this hydrogen permeable membrane, thus contributing to higher performance and downsizing of high-performance hydrogen purifiers, for example. The phosphorus included as an alloying element markedly enhances the high-temperature amorphous stability. Even in a high-temperature state above 300° C., crystallization is greatly suppressed, enabling the non-crystalline structure to be maintained over a long period of time. The use of such a membrane makes it possible to carry out a high-temperature heating operation in the above-described high-performance hydrogen purifier, for example, enabling productivity to be further enhanced. 
   Next, the composition of the non-crystalline nickel-zirconium alloy and the non-crystalline zirconium-nickel alloy in the inventive hydrogen-separation permeation membranes is described. 
   (A) Non-Crystalline Nickel-Zirconium Alloy: 
   (a-1) Nickel: 
   The nickel constituent within the non-crystalline nickel-zirconium alloy, when present together with the zirconium constituent, forms by means of quenching solidification a non-crystalline structure that exhibits a hydrogen-separating and permeating ability and also serves to enhance the strength of the membrane. At a nickel content of less than 44%, the high strength desired of the membrane cannot be ensured. On the other hand, at a content of more than 75%, the relative proportion of zirconium within the alloy becomes small, which tends to result in a decline in the hydrogen-separating and permeating ability. Accordingly, the nickel content has been set at 44 to 75%. A nickel content of 50 to 69% is preferred. 
   (b-1) Aluminum: 
   As noted above, the aluminum constituent acts to enhance the high-temperature amorphous stability, and stably maintains the non-crystalline structure even at elevated temperatures above 300° C. However, at an aluminum content below 0.2%, a sufficient amorphous stability enhancing effect is not achieved. On the other hand, at a content greater than 16%, the hydrogen-separating and permeating ability of the membrane tends to decrease. Hence, the aluminum content has been set at 0.2 to 16%, and preferably 1 to 13%. 
   (c-1) Vanadium and Niobium: 
   These constituents form a non-crystalline structure together with the nickel and zirconium constituents. As noted above, vanadium and niobium serve to further enhance the hydrogen-separating and permeating ability. However, at a vanadium and niobium content of less than 0.2%, sufficient enhancement of this ability cannot be achieved. On the other hand, at a vanadium and niobium content of more than 12%, stable formation of a non-crystalline structure is difficult. Accordingly, the vanadium and niobium content has been set at 0.2 to 12%, and preferably 0.5 to 10%. 
   (d-1) Phosphorus: 
   As noted above, the phosphorus constituent improves the high-temperature amorphous stability and serves to stably ensure a non-crystalline structure even at elevated temperatures above 300° C. At a phosphorus content below 0.1%, sufficient enhancement of the amorphous stability is not achieved, whereas at a content above 10%, the hydrogen-separating and permeating ability of the membrane shows a tendency to decrease. Accordingly, the phosphorus content was set at 0.1 to 10%, and preferably 0.2 to 8%. 
   At a combined niobium and phosphorus content of more than 18%, the relative content of nickel and zirconium becomes too small, making it difficult to stably form a non-crystalline structure. For this reason, the combined amount of niobium and phosphorus has been set at not more than 18%. 
   (B) Non-Crystalline Zirconium-Nickel Alloy: 
   (a-2) Zirconium: 
   The zirconium constituent within the non-crystalline zirconium-nickel alloy, when present together with the nickel constituent, forms by means of quenching solidification a non-crystalline structure that exhibits a hydrogen-separating and permeating ability, and moreover enhances the hydrogen-separating and permeating ability of the membrane. At a zirconium content of less than 44%, the excellent hydrogen-separating and permeating ability desired of the membrane cannot be ensured. On the other hand, at a content of more than 75%, the relative proportion of nickel within the alloy becomes too small, which results in an abrupt drop in the membrane strength. Accordingly, the zirconium content has been set at 44 to 75%. A zirconium content of 50 to 70% is preferred. 
   If the nickel content in the non-crystalline zirconium-nickel alloy exceeds 43%, the membrane strength increases, but the relative proportion of zirconium becomes low, which tends to lower the hydrogen-separating and permeating ability of the membrane and thus makes it difficult to ensure a high hydrogen-separating and permeating ability. Hence, the upper limit in the nickel content was set at 43%. 
   (b-2) Aluminum: 
   As noted above, the aluminum constituent acts to enhance the high-temperature amorphous stability, and stably maintains the non-crystalline structure even at elevated temperatures above 300° C. However, at an aluminum content below 0.2%, a sufficient amorphous stability enhancing effect is not achieved. On the other hand, at a content greater than 16%, the hydrogen-separating and permeating ability of the membrane tends to decrease. Hence, the aluminum content has been set at 0.2 to 16%, and preferably 1 to 13%. 
   (c-2) Vanadium and Niobium: 
   These constituents form a non-crystalline structure together with the nickel and zirconium constituents. As noted above, vanadium and niobium serve to further enhance the hydrogen-separating and permeating ability. However, at a vanadium and niobium content of less than 0.2%, sufficient enhancement of this ability cannot be achieved. On the other hand, at a vanadium and niobium content of more than 20%, stable formation of a non-crystalline structure is difficult. Accordingly, the vanadium and niobium content has been set at 0.2 to 20%, and preferably 0.5 to 15%. 
   (d-2) Phosphorus: 
   As noted above, the phosphorus constituent improves the high-temperature amorphous stability and serves to stably ensure a non-crystalline structure even at elevated temperatures above 300° C. At a phosphorus content below 0.1%, sufficient enhancement of the amorphous stability is not achieved, whereas at a content above 15%, the hydrogen-separating and permeating ability of the membrane tends to decrease. Accordingly, the phosphorus content was set at 0.1 to 15%, and preferably 0.2 to 10%. 
   At a combined niobium and phosphorus content of more than 18%, the relative content of nickel and zirconium becomes too small, making it difficult to stably form a non-crystalline structure. For this reason, the combined amount of niobium and phosphorus has been set at not more than 18%. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a schematic view of a high-performance hydrogen purifier. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The hydrogen permeable membrane of the invention is illustrated more fully in the following examples. 
   Inventive Hydrogen Permeable Membranes 1 to 29, and Prior-Art Hydrogen Permeable Membranes 1 to 12 
   Sponge zirconium of 99.5% purity, nickel of 99.9% purity and aluminum of 99.9% purity were used as the starting materials. These starting materials were blended in specific proportions and argon arc melted in a high-purity argon atmosphere to form 300 g ingots. The ingots were re-melted in a melting furnace within an argon atmosphere, and the melt was sprayed at a pressure of 0.05 MPa onto the surface of a water-cooled copper roll rotating at a speed of 33 m/s (nickel-zirconium alloys) or 20 m/s (zirconium-nickel alloys), thereby forming nickel-zirconium (or zirconium-nickel) alloy foils of the compositions shown in Table 1 (nickel-zirconium alloys) or Table 2 (zirconium-nickel alloys) which had a width of 30 mm and a thickness of 30 μm (nickel-zirconium alloys) or a width of 30 mm and a thickness of 50 μm (zirconium-nickel alloys). Each of these foils was cut to planar dimensions of 30×100 mm, thereby preparing inventive hydrogen permeable membranes 1 to 13 (nickel-zirconium alloys; Table 1) and 14 to 29 (zirconium-nickel alloys; Table 2), and preparing also prior-art hydrogen permeable membranes 1 to 6 (nickel-zirconium alloys; Table 1) and 7 to 12 (zirconium-nickel alloys; Table 2) which did not contain aluminum as an alloying element. 
   The microstructures of these hydrogen permeable membranes were examined by x-ray diffraction analysis and found in each case to be non-crystalline. 
   A palladium thin film was then formed by vapor deposition to a thickness of 10 nm on both sides of each of the above hydrogen permeable membranes. The membrane was then placed between two nickel reinforcing frames, each having a lateral outside dimension of 35 mm, a vertical outside dimension of 105 mm, a frame width of 5 mm and a frame thickness of 0.2 mm, and the membrane was ultrasonically welded to the reinforcing frames and thereby fixed. The membrane was then installed in this reinforced state within the reaction chamber of a high-performance hydrogen purifier of the construction shown in  FIG. 1 , and the interior of the reaction chamber was heated to 300° C. or 350° C. 
   In the case of inventive hydrogen permeable membranes 1 to 13 and prior-art hydrogen permeable membranes 1 to 6, a hydrogen-containing feed gas obtained by steam reforming LNG and containing 66.5 vol % of H 2 , 17 vol % of CO 2  and 0.5 vol % of CO was fed through an inlet into the left-hand reaction chamber while holding the internal pressure within this chamber at 0.3 MPa. 
   In the case of inventive hydrogen permeable membranes 14 to 29 and prior-art hydrogen permeable membranes 7 to 12, a hydrogen-containing feed gas obtained by steam reforming methanol and containing 70 vol % of H 2 , 22 vol % of CO 2  and 0.5 vol % of CO was fed through an inlet into the left-hand reaction chamber while holding the internal pressure within this chamber at 0.3 MPa. 
   At the same time, hydrogen purifying treatment in which the separated and purified high-purity hydrogen gas was drawn off from the outlet while holding the internal pressure in the right-hand chamber to 0.1 MPa was carried out, and the flow rate of the separated and purified high-purity hydrogen gas was measured with a gas flow meter 30 minutes after the start of treatment at reaction chamber heating temperatures of 300° C. and 350° C. The separated and purified high-purity hydrogen gas was also analyzed with a gas chromatograph every 100 hours following the start of hydrogen purification treatment, and the treatment time until the CO 2  gas content within the separated and purified high-purity hydrogen gas rose to 100 ppm was measured. This treatment time was regarded as the life of the membrane. The results of these measurements are shown in Tables 1 and 2. 
   
     
       
             
             
             
           
             
             
             
             
             
           
             
             
             
             
             
             
           
             
             
             
             
             
             
             
             
           
             
             
             
             
             
             
             
             
             
           
         
             
                 
               TABLE 1 
             
           
           
             
                 
                 
             
             
                 
               Reaction 
               Reaction 
             
             
                 
               temperature 
               temperature 
             
             
                 
               of 300° C. 
               of 350° C. 
             
           
        
         
             
                 
               High-purity 
                 
               High-purity 
                 
             
           
        
         
             
                 
               Composition (atom %) 
               hydrogen gas 
               Life of 
               hydrogen gas 
               Life of 
             
           
        
         
             
               Type of 
                 
                 
               Zr + 
               flow rate 
               membrane 
               flow rate 
               membrane 
             
             
               membrane 
               Ni 
               Al 
               impurities 
               (ml/min) 
               (hours) 
               (ml/min) 
               (hours) 
             
             
                 
             
           
        
         
             
               Hydrogen 
               1 
               44.12 
               9.52 
               balance 
               34.8 
               2,200 
               46.2 
               900 
             
             
               permeable 
               2 
               50.10 
               9.77 
               balance 
               33.5 
               2,400 
               45.0 
               1,000 
             
             
               membranes 
               3 
               54.17 
               9.45 
               balance 
               32.1 
               2,600 
               43.0 
               1,200 
             
             
               according to 
               4 
               60.75 
               9.44 
               balance 
               30.8 
               2,500 
               41.4 
               1,100 
             
             
               invention 
               5 
               65.51 
               9.50 
               balance 
               30.0 
               2,500 
               40.5 
               1,100 
             
             
                 
               6 
               69.57 
               9.34 
               balance 
               28.9 
               2,400 
               39.3 
               1,000 
             
             
                 
               7 
               74.92 
               9.63 
               balance 
               27.6 
               2,300 
               38.2 
               900 
             
             
                 
               8 
               60.80 
               0.52 
               balance 
               34.3 
               2,300 
               45.1 
               900 
             
             
                 
               9 
               61.24 
               1.16 
               balance 
               33.6 
               2,500 
               44.6 
               1,100 
             
             
                 
               10 
               61.10 
               3.75 
               balance 
               32.1 
               2,600 
               43.0 
               1,200 
             
             
                 
               11 
               61.56 
               7.90 
               balance 
               30.5 
               2,500 
               41.2 
               1,100 
             
             
                 
               12 
               61.11 
               12.96 
               balance 
               28.9 
               2,400 
               39.2 
               1,000 
             
             
                 
               13 
               60.71 
               15.91 
               balance 
               27.5 
               2,200 
               38.0 
               800 
             
             
               Prior-art 
               1 
               50.16 
               — 
               balance 
               35.2 
               1,900 
               46.3 
               600 
             
             
               Hydrogen 
               2 
               60.81 
               — 
               balance 
               33.2 
               2,100 
               44.3 
               700 
             
             
               permeable 
               3 
               69.73 
               — 
               balance 
               29.1 
               2,000 
               39.1 
               600 
             
             
               membranes 
               4 
               62.34 
               Cu: 0.82 
               balance 
               33.4 
               2,100 
               44.6 
               700 
             
             
                 
               5 
               60.50 
               Cu: 5.63 
               balance 
               30.9 
               2,100 
               41.6 
               600 
             
             
                 
               6 
               58.70 
                Cu: 14.35 
               balance 
               27.8 
               1,900 
               38.1 
               600 
             
             
                 
             
           
        
       
     
   
                                                                                                                                                       TABLE 2                           Reaction   Reaction           temperature   temperature           of 300° C.   of 350° C.                High-purity       High-purity                    Composition (atom %)   hydrogen gas   Life of   hydrogen gas   Life of            Type of           Ni +   flow rate   membrane   flow rate   membrane       membrane   Zr   Al   impurities   (ml/min)   (hours)   (ml/min)   (hours)                    Hydrogen   14   44.08   14.78   balance (41.14)   24.3   2,200   33.4   900       permeable   15   47.25   9.89   balance (42.86)   25.4   2,300   34.5   900       membranes   16   50.63   6.61   balance (42.76)   26.1   2,400   34.9   1,000       according to   17   54.57   6.75   balance (38.68)   26.8   2,500   35.8   1,100       invention   18   58.29   6.21   balance (35.50)   27.3   2,600   36.5   1,200           19   62.43   6.24   balance (31.33)   28.4   2,500   37.8   1,100           20   66.40   6.47   balance (27.13)   29.2   2,400   38.4   1,000           21   71.69   6.56   balance (21.75)   29.9   2,200   39.5   900           22   74.85   6.26   balance (18.89)   30.7   2,100   40.3   800           23   64.48   0.53   balance (34.99)   30.8   2,200   40.5   900           24   64.35   1.19   balance (34.46)   30.2   2,300   39.7   1,000           25   64.16   3.65   balance (32.19)   29.0   2,400   38.3   1,100           26   64.05   7.89   balance (28.06)   28.3   2,500   37.8   1,100           27   63.95   10.10   balance (25.95)   27.0   2,500   36.4   1,100           28   59.35   14.93   balance (25.72)   25.9   2,400   34.8   1,000           29   56.61   17.93   balance (25.45)   24.4   2,200   33.6   900       Prior-art   7   59.53   —   balance (40.47)   27.3   1,800   36.5   500       hydrogen   8   65.83   —   balance (34.17)   29.1   2,000   38.6   600       permeable   9   71.51   —   balance (28.49)   30.6   1,900   40.4   600       membranes   10   61.39   Cu: 0.56   balance (38.05)   28.4   2,000   37.9   600           11   60.45   Cu: 4.83   balance (34.72)   25.4   1,900   34.5   500           12   55.31    Cu: 14.89   balance (29.80)   24.2   1,800   33.3   500                    
Inventive Hydrogen Permeable Membranes 30 to 79, and Prior-Art Hydrogen Permeable Membranes 13 to 24
 
   Sponge zirconium of 99.5% purity, nickel shot of 99.9% purity, Ni-51% V master alloy, and Ni-60% Nb master alloy were used as the starting materials. These starting materials were blended in specific proportions and argon arc melted in a high-purity argon atmosphere to form 300 g ingots. The ingots were re-melted in a melting furnace within an argon atmosphere, and the melt was sprayed at a pressure of 0.03 MPa onto the surface of a water-cooled copper roll rotating at a speed of 25 m/s (nickel-zirconium alloys) or 18 m/s (zirconium-nickel alloys), thereby forming nickel-zirconium alloy foils of the compositions shown in Table 3 which had a width of 20 mm and a thickness of 30 μm and zirconium-nickel alloy foils of the composition shown in Table 4 which had a width of 20 mm and a thickness of 40 μm. Each of these foils was cut to dimensions of 20×80 mm, thereby preparing hydrogen permeable membranes 30 to 79 according to the invention and preparing also comparative hydrogen permeable membranes 13 to 24 which did not contain vanadium and niobium as alloying elements and corresponded to the foregoing prior-art hydrogen permeable membranes. 
   The microstructures of these hydrogen permeable membranes were examined by x-ray diffraction analysis and found in each case to be non-crystalline. 
   A palladium thin film was then formed by vapor deposition to a thickness of 10 nm on both sides of each of the above hydrogen permeable membranes. The membrane was then placed between two nickel reinforcing frames, each having a lateral outside dimension of 25 mm, a vertical outside dimension of 85 mm, a frame width of 5 mm and a frame thickness of 0.2 mm, and the membrane was ultrasonically welded to the reinforcing frames and thereby fixed. The membrane was then installed in this reinforced state within the reaction chamber of a high-performance hydrogen purifier of the construction shown in  FIG. 1 . 
   In the case of nickel-zirconium alloys, the interior of the reaction chamber was heated to 300° C., a hydrogen-containing feed gas obtained by steam reforming methanol and containing 70 vol % of H 2  and 22 vol % of CO 2 , with the balance being high-temperature steam and other components, was fed through an inlet into the left-hand reaction chamber while holding the internal pressure within this chamber at 0.5 MPa. 
   In the case of zirconium-nickel alloys, the interior of the reaction chamber was heated to 300° C., a hydrogen-containing feed gas obtained by steam reforming town gas (e.g. coal gas) and containing 66.5 vol % of H 2  and 20 vol % of CO 2 , with the balance being high-temperature steam and other components, was fed through an inlet into the left-hand reaction chamber while holding the internal pressure within this chamber at 0.5 MPa. 
   At the same time, hydrogen purifying treatment in which the separate and purified high-purity hydrogen gas is drawn off from the outlet while holding the internal pressure within the right-hand chamber to 0.1 MPa was carried out, and the flow rate of the separated and purified high-purity hydrogen gas was measured with a gas flow meter 30 minutes after the start of treatment. The measurement results are shown in Tables 3 and 4. The hydrogen separating and permeating abilities of the membranes were rated based on these results. 
   The content of CO 2  gas, which is an impurity, in the above-described separated and purified high-purity hydrogen gases was measured using a gas chromatograph. In each case, CO 2  was not detected. 
   
     
       
             
             
             
           
             
             
             
             
             
             
           
             
             
             
             
             
             
             
           
         
             
                 
               TABLE 3 
             
           
           
             
                 
                 
             
             
                 
                 
               High-purity 
             
             
                 
               Composition (atom %) 
               hydrogen gas 
             
           
        
         
             
               Type of 
                 
                 
                 
               Zr + 
               flow rate 
             
             
               membrane 
               Ni 
               V 
               Nb 
               impurities 
               (ml/min) 
             
             
                 
             
           
        
         
             
               Hydrogen 
               30 
               44.11 
               5.24 
               — 
               balance (50.65) 
               48.3 
             
             
               permeable 
               31 
               50.64 
               5.33 
               — 
               balance (44.03) 
               47.5 
             
             
               membranes 
               32 
               61.42 
               5.29 
               — 
               balance (33.29) 
               44.2 
             
             
               according to 
               33 
               68.83 
               5.30 
               — 
               balance (25.87) 
               42.6 
             
             
               invention 
               34 
               74.68 
               5.21 
               — 
               balance (20.11) 
               39.3 
             
             
                 
               35 
               44.25 
               — 
               1.55 
               balance (54.20) 
               48.1 
             
             
                 
               36 
               50.31 
               — 
               1.47 
               balance (48.22) 
               47.3 
             
             
                 
               37 
               61.33 
               — 
               1.49 
               balance (37.18) 
               44.2 
             
             
                 
               38 
               68.71 
               — 
               1.53 
               balance (29.76) 
               42.3 
             
             
                 
               39 
               74.93 
               — 
               1.54 
               balance (23.53) 
               39.0 
             
             
                 
               40 
               63.50 
               0.22 
               — 
               balance (36.28) 
               39.7 
             
             
                 
               41 
               63.06 
               0.58 
               — 
               balance (36.36) 
               42.8 
             
             
                 
               42 
               62.42 
               3.50 
               — 
               balance (34.08) 
               45.2 
             
             
                 
               43 
               62.14 
               9.87 
               — 
               balance (27.99) 
               48.1 
             
             
                 
               44 
               61.98 
               11.96 
               — 
               balance (26.06) 
               47.5 
             
             
                 
               45 
               63.39 
               — 
               0.26 
               balance (36.35) 
               40.0 
             
             
                 
               46 
               63.21 
               — 
               0.54 
               balance (36.25) 
               43.4 
             
             
                 
               47 
               62.86 
               — 
               5.62 
               balance (31.52) 
               45.5 
             
             
                 
               48 
               62.08 
               — 
               9.91 
               balance (28.01) 
               47.7 
             
             
                 
               49 
               61.84 
               — 
               11.88 
               balance (26.28) 
               47.3 
             
             
                 
               50 
               65.42 
               0.08 
               0.15 
               balance (34.35) 
               39.4 
             
             
                 
               51 
               64.15 
               0.26 
               0.31 
               balance (35.28) 
               43.1 
             
             
                 
               52 
               59.17 
               2.31 
               3.28 
               balance (35.24) 
               45.7 
             
             
                 
               53 
               54.61 
               3.15 
               6.79 
               balance (35.45) 
               48.4 
             
             
                 
               54 
               50.24 
               7.25 
               4.70 
               balance (37.81) 
               49.2 
             
             
               Comparative 
               13 
               50.21 
               — 
               — 
               balance (49.79) 
               35.2 
             
             
               hydrogen 
               14 
               61.07 
               — 
               — 
               balance (38.93) 
               33.2 
             
             
               permeable 
               15 
               68.62 
               — 
               — 
               balance (31.38) 
               30.0 
             
             
               membranes 
               16 
               63.54 
               — 
               Cu: 
               balance (35.91) 
               33.5 
             
             
                 
                 
                 
                 
               0.55 
             
             
                 
               17 
               61.42 
               — 
               Cu: 
               balance (33.33) 
               30.7 
             
             
                 
                 
                 
                 
               5.25 
             
             
                 
               18 
               53.52 
               — 
               Cu: 
               balance (34.63) 
               29.0 
             
             
                 
                 
                 
                 
               11.85 
             
             
                 
             
           
        
       
     
   
                                                                                       TABLE 4                               High-purity           Composition (atom %)   hydrogen gas            Type of               Ni +   flow rate       membrane   Zr   V   Nb   impurities   (ml/min)                    Hydrogen   55   44.11   12.96   —   balance (42.89)   37.5       permeable   56   50.06   9.83   —   balance (40.11)   39.7       membranes   57   60.74   9.66   —   balance (29.60)   41.1       according to   58   69.65   9.73   —   balance (20.62)   43.3       invention   59   74.88   9.68   —   balance (15.44)   43.7           60   44.07   —   13.31   balance (42.62)   37.1           61   50.45   —   6.65   balance (42.90)   39.3           62   61.07   —   6.55   balance (32.38)   40.4           63   69.77   —   6.60   balance (23.63)   41.9           64   74.51   —   6.62   balance (18.87)   42.2           65   58.56   0.26   —   balance (41.18)   37.4           66   58.60   0.58   —   balance (40.82)   38.7           67   58.61   3.50   —   balance (37.89)   40.1           68   58.64   14.86   —   balance (26.50)   43.4           69   58.61   19.90   —   balance (21.49)   43.9           70   60.27   —   0.23   balance (39.50)   37.6           71   60.25   —   0.54   balance (39.21)   38.9           72   60.24   —   2.91   balance (36.85)   40.2           73   60.31   —   14.93   balance (24.76)   42.9           74   60.28   —   19.87   balance (19.85)   43.3           75   65.73   0.19   0.07   balance (34.01)   37.2           76   63.35   0.40   0.19   balance (36.06)   39.1           77   59.47   4.32   5.29   balance (30.92)   41.4           78   56.59   6.19   8.73   balance (28.49)   42.2           79   51.37   9.51   10.46   balance (28.66)   42.8       Prior-art   19   60.05   —   —   balance (39.95)   29.2       hydrogen   20   66.24   —   —   balance (33.76)   31.0       permeable   21   72.37   —   —   balance (27.63)   32.4       membranes   22   60.45   —   Cu:   balance (38.92)   29.9                       0.63           23   61.31   —   Cu:   balance (33.15)   27.0                       5.54           24   53.52   —   Cu:   balance (26.96)   25.2                       19.52                    
Inventive Hydrogen Permeable Membranes 80 to 107, and Prior-Art Hydrogen Permeable Membranes 25 to 36
 
   Sponge zirconium of 99.5% purity, nickel shot of 99.9% purity, Ni-60% Nb master alloy, and Ni-25% P master alloy were used as the starting materials. These starting materials were blended specific proportions and argon arc melted in a high-purity argon atmosphere to form 300 g ingots. The ingots were re-melted in a melting furnace within an argon atmosphere, and the melt was sprayed at a pressure of 0.03 MPa onto the surface of a water-cooled copper roll rotating at a speed of 25 m/s (nickel-zirconium alloys) or 18 m/s (zirconium-nickel alloys), thereby forming nickel-zirconium alloy foils of the compositions shown in Table 5 which had a width of 20 mm and a thickness of 30 μm and zirconium-nickel alloy foils of the composition shown in Table 6 which had a width of 20 mm and a thickness of 40 μm. Each of these foils was cut to dimensions of 20×80 mm, thereby preparing hydrogen permeable membranes 80 to 107 according to the invention and preparing also prior-art hydrogen permeable membranes 25 to 36 which did not contain niobium and phosphorus as alloying elements and corresponded to the foregoing prior-art hydrogen permeable membranes. 
   The microstructures of these hydrogen permeable membranes were examined by x-ray diffraction analysis and found in each case to be non-crystalline. 
   A palladium thin film was then formed by vapor deposition to a thickness of 10 nm on both sides of each of the above hydrogen permeable membranes. The membrane was then placed between two nickel reinforcing frames, each having a lateral outside dimension of 25 mm, a vertical outside dimension of 85 mm, a frame width of 5 mm and a frame thickness of 0.2 mm, and the membrane was ultrasonically welded to the reinforcing frames and thereby fixed. The membrane was then installed in this reinforced state within the reaction chamber of a high-performance hydrogen purifier of the construction shown in  FIG. 1 , and the interior of the reaction chamber was heated to 300° C. or 350° C. in each case. A hydrogen-containing feed gas obtained by steam reforming methanol and containing 70 vol % of H 2  and 22 vol % of CO 2 , with the balance being high-temperature steam and other components, was fed through an inlet into the left-hand reaction chamber while holding the internal pressure within this chamber at 0.4 MPa. At the same time, hydrogen purifying treatment in which the separated and purified high-purity hydrogen gas is drawn off from the outlet while holding the internal pressure within the right-hand chamber to 0.1 MPa was carried out, and the flow rate of the separated and purified high-purity hydrogen gas was measured with a gas flow meter 1 hour after the start of treatment. The hydrogen separating and permeating abilities of the membranes were rated based on these results. In addition, the content of CO 2  gas, which is an impurity, within the separated and purified high-purity hydrogen gas was analyzed with a gas chromatograph every 100 hours following the start of hydrogen purification treatment, and the treatment time until the CO 2  gas content within the separated and purified high-purity hydrogen gas rose to 100 ppm was measured. This treatment time was regarded as the life of the membrane. The results of these measurements are shown in Tables 5 and 6. 
   
     
       
             
             
             
           
             
             
             
             
             
           
             
             
             
             
             
             
           
             
             
             
             
             
             
             
             
             
           
             
             
             
             
             
             
             
             
             
             
           
         
             
                 
               TABLE 5 
             
           
           
             
                 
                 
             
             
                 
               Reaction 
               Reaction 
             
             
                 
               temperature 
               temperature 
             
             
                 
               of 300° C. 
               of 350° C. 
             
           
        
         
             
                 
               High-purity 
                 
               High-purity 
                 
             
           
        
         
             
                 
               Composition (atom %) 
               hydrogen gas 
               Life of 
               hydrogen gas 
               Life of 
             
           
        
         
             
               Type of 
                 
                 
                 
               Zr + 
               flow rate 
               membrane 
               flow rate 
               membrane 
             
             
               membrane 
               Ni 
               Nb 
               P 
               impurities 
               (ml/min) 
               (hours) 
               (ml/min) 
               (hours) 
             
             
                 
             
           
        
         
             
               Hydrogen 
               80 
               44.08 
               2.28 
               1.53 
               balance 
               35.8 
               2,900 
               48.1 
               1,300 
             
             
               permeable 
               81 
               51.13 
               2.21 
               1.64 
               balance 
               34.4 
               3,100 
               46.3 
               1,400 
             
             
               membranes 
               82 
               59.26 
               2.19 
               1.52 
               balance 
               32.9 
               3,200 
               44.3 
               1,500 
             
             
               according to 
               83 
               68.94 
               2.23 
               1.57 
               balance 
               30.7 
               3,100 
               41.8 
               1,400 
             
             
               invention 
               84 
               74.78 
               2.27 
               1.50 
               balance 
               29.3 
               2,900 
               39.0 
               1,300 
             
             
                 
               85 
               62.53 
               0.23 
               3.70 
               balance 
               30.6 
               3,100 
               42.1 
               1,400 
             
             
                 
               86 
               62.34 
               0.69 
               3.72 
               balance 
               32.0 
               3,100 
               43.4 
               1,400 
             
             
                 
               87 
               57.85 
               9.86 
               3.67 
               balance 
               34.7 
               3,000 
               46.4 
               1,400 
             
             
                 
               88 
               57.37 
               11.85 
               3.75 
               balance 
               36.1 
               2,900 
               48.0 
               1,300 
             
             
                 
               89 
               60.51 
               5.15 
               0.13 
               balance 
               34.1 
               2,900 
               46.4 
               1,200 
             
             
                 
               90 
               60.34 
               5.18 
               0.24 
               balance 
               33.1 
               3,100 
               45.0 
               1,400 
             
             
                 
               91 
               56.44 
               5.14 
               7.91 
               balance 
               30.5 
               3,100 
               41.6 
               1,400 
             
             
                 
               92 
               54.72 
               5.12 
               9.78 
               balance 
               29.6 
               3,000 
               40.4 
               1,100 
             
             
               Prior-art 
               25 
               50.20 
               — 
               — 
               balance 
               27.3 
               1,900 
               35.3 
               600 
             
             
               hydrogen 
               26 
               60.85 
               — 
               — 
               balance 
               25.6 
               2,100 
               34.2 
               700 
             
             
               permeable 
               27 
               69.54 
               — 
               — 
               balance 
               22.8 
               2,000 
               30.7 
               600 
             
             
               membranes 
               28 
               62.40 
               — 
               Cu: 0.55 
               balance 
               26.1 
               2,100 
               33.8 
               700 
             
             
                 
               29 
               60.50 
               — 
               Cu: 5.25 
               balance 
               23.8 
               2,100 
               31.7 
               600 
             
             
                 
               30 
               58.70 
               — 
               Cu: 9.63 
               balance 
               21.6 
               1,900 
               29.6 
               600 
             
             
                 
             
           
        
       
     
   
   
     
       
             
             
             
           
             
             
             
             
             
           
             
             
             
             
             
             
           
             
             
             
             
             
             
             
             
             
           
             
             
             
             
             
             
             
             
             
             
           
         
             
                 
               TABLE 6 
             
           
           
             
                 
                 
             
             
                 
               Reaction 
               Reaction 
             
             
                 
               temperature 
               temperature 
             
             
                 
               of 300° C. 
               of 350° C. 
             
           
        
         
             
                 
               High-purity 
                 
               High-purity 
                 
             
           
        
         
             
                 
               Composition (atom %) 
               hydrogen gas 
               Life of 
               hydrogen gas 
               Life of 
             
           
        
         
             
               Type of 
                 
                 
                 
               Ni + 
               flow rate 
               membrane 
               flow rate 
               membrane 
             
             
               membrane 
               Zr 
               Nb 
               P 
               impurities 
               (ml/min) 
               (hours) 
               (ml/min) 
               (hours) 
             
             
                 
             
           
        
         
             
               Hydrogen 
               93 
               44.13 
               6.59 
               6.37 
               balance (42.91) 
               30.1 
               2,900 
               40.1 
               1,300 
             
             
               permeable 
               94 
               50.37 
               5.04 
               2.14 
               balance (42.45) 
               30.9 
               2,900 
               40.3 
               1,300 
             
             
               membranes 
               95 
               60.22 
               3.69 
               2.12 
               balance (33.97) 
               32.6 
               3,000 
               42.4 
               1,400 
             
             
               according to 
               96 
               65.91 
               3.64 
               2.17 
               balance (28.28) 
               34.3 
               3,100 
               44.4 
               1,400 
             
             
               invention 
               97 
               74.65 
               3.67 
               2.20 
               balance (19.48) 
               35.0 
               2,900 
               45.5 
               1,300 
             
             
                 
               98 
               62.53 
               0.21 
               1.55 
               balance (35.71) 
               31.2 
               3,000 
               40.5 
               1,400 
             
             
                 
               99 
               62.34 
               1.08 
               1.57 
               balance (35.01) 
               31.9 
               3,000 
               41.4 
               1,400 
             
             
                 
               100 
               58.72 
               9.86 
               1.54 
               balance (29.88) 
               33.8 
               2,900 
               43.7 
               1,300 
             
             
                 
               101 
               55.26 
               14.31 
               1.52 
               balance (28.91) 
               34.6 
               2,800 
               44.6 
               1,300 
             
             
                 
               102 
               50.37 
               19.83 
               1.59 
               balance (28.21) 
               35.1 
               2,700 
               45.2 
               1,200 
             
             
                 
               103 
               61.29 
               7.31 
               0.13 
               balance (31.27) 
               34.9 
               2,900 
               44.9 
               1,200 
             
             
                 
               104 
               60.50 
               7.28 
               0.26 
               balance (31.96) 
               34.5 
               3,000 
               44.5 
               1,400 
             
             
                 
               105 
               56.01 
               7.28 
               4.79 
               balance (31.92) 
               33.7 
               3,100 
               43.8 
               1,400 
             
             
                 
               106 
               52.37 
               7.34 
               9.55 
               balance (30.74) 
               32.1 
               3,100 
               42.0 
               1,400 
             
             
                 
               107 
               47.25 
               7.30 
               14.89 
               balance (30.56) 
               30.4 
               3,000 
               40.0 
               1,300 
             
             
               Prior-art 
               31 
               58.67 
               — 
               — 
               balance (41.33) 
               24.1 
               1,800 
               32.3 
               500 
             
             
               hydrogen 
               32 
               65.12 
               — 
               — 
               balance (34.88) 
               26.3 
               2,000 
               34.6 
               600 
             
             
               permeable 
               33 
               70.38 
               — 
               — 
               balance (29.62) 
               27.0 
               1,900 
               35.8 
               600 
             
             
               membranes 
               34 
               60.84 
               — 
               Cu: 0.58 
               balance (38.58) 
               25.1 
               2,000 
               33.6 
               600 
             
             
                 
               35 
               59.28 
               — 
               Cu: 5.17 
               balance (35.55) 
               22.5 
               1,900 
               31.0 
               500 
             
             
                 
               36 
               58.63 
               — 
                Cu: 14.21 
               balance (27.16) 
               21.6 
               1,800 
               29.6 
               500 
             
             
                 
             
           
        
       
     
   
   INDUSTRIAL APPLICABILITY 
   As is apparent from the above tables, a comparison of inventive hydrogen permeable membranes 1 to 29 with prior-art hydrogen permeable membranes 1 to 12 which do not contain aluminum as an alloying element shows that even when aluminum is present as an alloying element, there is substantially no change in the production and flow rate of separated and purified high-purity hydrogen gas (i.e., in the hydrogen separating and permeating action) at a normal heating and operating temperature of 300° C. and even at a high-temperature heating and operating temperature of 350° C. However, because inventive hydrogen permeable membranes 1 to 29 which contain aluminum as an alloying element all have excellent high-temperature amorphous stability, they clearly exhibit a much longer service life than prior-art hydrogen-separation permeation membranes 1 to 12, particularly in high-temperature heating operation. 
   As mentioned above, the hydrogen permeable membranes of the invention have excellent high-temperature amorphous stability, with crystallization being clearly suppressed even at elevated temperatures above 300° C. so that a non-crystalline microstructure is maintained. Accordingly, this enables the high-temperature heating operation of equipment such as high-performance hydrogen purifiers, contributing to a further improvement in productivity. 
   As is also apparent from the above tables, a comparison of inventive hydrogen permeable membranes 30 to 79 which contain vanadium and/or niobium as alloying elements with comparative hydrogen permeable membranes 13 to 24 which do not contain these elements clearly shows that, due to the effects of the vanadium and/or niobium present as alloying elements, the former membranes exhibit a much better hydrogen-separating and permeating ability than the latter membranes. 
   As noted above, because these hydrogen permeable membranes according to the invention exhibit a much better hydrogen-separating and permeating ability, they can contribute to a higher performance and downsizing in high-performance hydrogen purifiers. 
   As is additionally apparent from the above tables, owing to the effects of the niobium included as an alloying element, inventive hydrogen permeable membranes 80 to 107 all have an enhanced hydrogen-separating and permeating ability at an ordinary heating and operating temperature of 300° C. and also at an elevated heating and operating temperature of 350° C. That is, production/flow rate of the separated and purified high-purity hydrogen gas increases relative to prior-art hydrogen permeable membranes 25 to 36 which do not contain niobium. In addition, owing to the effects of the phosphorus in membranes 80 to 107 according to the invention, these inventive membranes also have an excellent high-temperature amorphous stability and thus clearly exhibit a much longer service life than prior-art hydrogen permeable membranes 25 to 36, particularly in high-temperature heating operation. 
   As noted above, in these inventive hydrogen permeable membranes, crystallization is markedly suppressed at elevated temperatures above 300° C. Hence, the membranes exhibit an excellent hydrogen-separating and permeating ability while at the same time having an excellent high-temperature amorphous stability that maintains a non-crystalline microstructure. This enables higher performance and downsizing to be achieved in high-performance hydrogen purifiers, in addition to which it allows high-temperature heating operation to be carried out, contributing to an even further improvement in productivity.