Process for preparing a composite metal membrane, the composite metal membrane prepared therewith and its use

Abstract

A process for preparing a composite metal membrane which contains a thin metal membrane with a desired thickness and a metallic membrane support with a porous structure, wherein metal membrane and membrane support consist of two different metals or metal alloys. The process is carried out by placing a precursor of the metal membrane on a non-porous precursor of the membrane support, the metal composite is then formed from the two precursors, the desired thickness of metal membrane is adjusted by mechanical working the metal composite and then the porous structure for the membrane support is produced.

1 . A process for preparing a composite metal membrane containing a thin metal membrane with a desired thickness and a metallic membrane support with a porous structure, wherein metal membrane and membrane support consist of two different metals or metal alloys, comprising placing a precursor of the metal membrane on a non-porous precursor of the membrane support, forming the metal composite from the two precursors, the desired thickness of the resulting metal membrane is adjusted by working the metal composite and then forming a porous structure in the membrane support is produced.  
     
     
         2 . The process according to  claim 1 , wherein the forming of the metal composite is produced by roll-bonding, explosive plating or diffusion welding.  
     
     
         3 . The process according to  claim 2 , wherein working the metal composite is achieved by rolling, pressing, flow moulding, deep drawing or combinations of these forming techniques.  
     
     
         4 . The process according to  claim 3 , wherein the composite metal membrane is formed into tubules by means of a drawing process.  
     
     
         5 . The process according to  claim 1 , wherein the metal membrane contains palladium or a palladium alloy and the precursor of the membrane support contains a two-phase or multi-phase metal alloy and the porous structure of the membrane support is produced by electrochemical dissolution of one or more alloy phases in the membrane support after preparation and working of the metal composite.  
     
     
         6 . The process according to  claim 5 , wherein the precursor of the membrane support contains a eutectic alloy and the porous structure is produced by electrochemical dissolution of the more electronegative) phase.  
     
     
         7 . The process according to  claim 6 , wherein characterised in that the precursor of the membrane support contains the eutectic alloy AgCu and the porous structure is produced by electrochemical dissolution of the Cu-rich phase.  
     
     
         8 . The process according to  claim 7 , wherein the copper content of the eutectic alloy is between 20 and 80 wt. %, with respect to the total weight of alloy.  
     
     
         9 . The process according to  claim 8 , wherein dissolution of the Cu-rich alloy phase is performed after thermal treatment at 400 to 750° C.  
     
     
         10 . The process according to  claim 9 , wherein the metal membrane contains a PdAg23, PdCu40 or a PdY alloy.  
     
     
         11 . The process according to  claim 1 , wherein the porous, metallic membrane support has a thickness of less than 100 and more than 20.  
     
     
         12 . The process according to  claim 1 , wherein the porous, metallic membrane support has a thickness between 50 and 20 μm.  
     
     
         13 . The process according to  claim 11 , wherein the metal membrane has a thickness of less than 20 μm and more than 1 μm.  
     
     
         14 . The process according to  claim 11 , wherein the metal membrane has a thickness 6 between 5 and 1 μm.  
     
     
         15 . The process according to  claim 1 , further comprising providing a precursor for a temporary covering membrane of a base metal alloy or a metal alloy in addition to the precursors for the metal membrane and the membrane support, placing the precursor for the metal membrane between the precursor for the membrane support and the precursor for the covering membrane, producing the metal composite from the three precursors, forming the desired thickness of metal membrane by working the metal composite and then producing the porous structure for the membrane support, dissolving the temporary covering membrane completely away before, at the same time as or after production of the porous structure in the membrane support.  
     
     
         16 . The process according to  claim 1 , further comprising providing a further non-porous precursor for a second membrane support in addition to the precursors for the metal membrane and the membrane support, placing the precursor for the metal membrane between the precursor for the membrane support and the precursor for the second membrane support, producing the metal composite from the three precursors, forming the desired thickness of the metal membrane by working the metal composite and then producing the porous structure for the membrane supports.  
     
     
         17 . A composite metal membrane comprising a metal membrane on a metallic membrane support with a porous structure, wherein the metal membrane has a thickness of 1 to 20 μm and the average pore size of the membrane support is greater than 0.5 and less than 10 μm.  
     
     
         18 . The composite metal membrane according to  claim 17 , wherein the average pore size of the membrane support is greater than the thickness of the metal membrane.  
     
     
         19 . The composite metal membrane according to  claim 17 , wherein the metal membrane contains palladium or a palladium alloy and the porous membrane support contains a two-phase or multi-phase metal alloy.  
     
     
         20 . The composite metal membrane according to  claim 18 , wherein the metal membrane contains palladium or a palladium alloy and the porous membrane support contains a two-phase or multi-phase metal alloy.  
     
     
         21 . The composite metal membrane according to  claim 19 , wherein the membrane support contains an eutectic alloy.  
     
     
         22 . The composite metal membrane according to  claim 21 , wherein the membrane support contains the eutectic alloy AgCu.  
     
     
         23 . The composite metal membrane according to  claim 22 , wherein the copper content of the eutectic alloy is between 20 and 80 wt. %, with respect to the total weight of the alloy.  
     
     
         24 . The composite metal membrane according to  claim 23 , wherein the metal membrane contains PdAg23, PdCu40 or a PdY alloy.  
     
     
         25 . The composite metal membrane according to  claim 17 , wherein the porous metallic membrane support has a thickness of less than 100 and more than 20.  
     
     
         26 . The composite metal membrane according to  claim 17 , wherein the porous metallic membrane support has a thickness between 50 and 20 μm.  
     
     
         27 . A composite metal membrane comprising a metal membrane between two metallic membrane supports with a porous structure, wherein the metal membrane has a thickness of 1 to 20 μm and the average pore size of the membrane support is greater than 0.5 and less than 10 μm.  
     
     
         28 . The composite metal membrane according to  claim 27 , wherein the average pore size of the membrane supports is greater than the thickness of the metal membrane.  
     
     
         29 . The composite metal membrane according to  claim 27 , wherein the metal membrane contains palladium or a palladium alloy and the porous membrane supports contain a two-phase or multi-phase metal alloy.  
     
     
         30 . The composite metal membrane according to  claim 28 , wherein the metal membrane contains palladium or a palladium alloy and the porous membrane supports contain a two-phase or multi-phase metal alloy.  
     
     
         31 . The composite metal membrane according to  claim 29 , wherein the membrane supports contain a eutectic alloy.  
     
     
         32 . The composite metal membrane according to  claim 31 , wherein the membrane supports contain the eutectic alloy AgCu.  
     
     
         33 . The composite metal membrane according to  claim 32 , wherein the copper content of the eutectic alloy is between 20 and 80 wt. %, with respect to the total weight of alloy.  
     
     
         34 . The composite metal membrane according to  claim 33 , wherein the metal membrane contains PdAg23, PdCu40 or a PdY alloy.  
     
     
         35 . The composite metal membrane according to  claim 27 , wherein the porous metallic membrane supports have a thickness of less than 100 and more than 20, preferably between 50 and 20 μm.  
     
     
         36 . A fuel cell containing the composite metal membrane according to  claim 17  as a gas separation membrane.  
     
     
         37 . A fuel cell containing the composite metal membrane according to  claim 27  as a gas separation membrane.  
     
     
         38 . A process for separating hydrogen from a gas mixture in a fuel cell comprising providing a gas mixture containing hydrogen through the gas separation membrane according to  claim 17 .  
     
     
         39 . A process for separating hydrogen from a gas mixture in a fuel cell comprising providing a gas mixture containing hydrogen through the gas separation membrane according to  claim 27 .  
     
     
         40 . A process for preparing a composite metal membrane containing a thin metal membrane with a desired thickness and a metallic membrane support with a porous structure, wherein metal membrane and membrane support consist of two different metals or metal alloys, comprising placing a metal foil having a first thickness as placing a precursor of the metal membrane on a non-porous metal foil having a second thickness as a precursor of the membrane support, wherein said first thickness is less than said second thickness, producing the metal composite by bonding the two precursors together, the desired thickness of the resulting metal membrane being reduced by working the metal composite and then dissolving out an alloy phase from the membrane support to thereby produce the porous structure in the membrane support.  
     
     
         41 . The process according to  claim 40 , wherein bonding of the metal composite is produced by roll-bonding, explosive plating or diffusion welding.  
     
     
         42 . The process according to  claim 42 , wherein working the metal composite is achieved by at least one of rolling, pressing, flow moulding, or deep drawing.  
     
     
         43 . The process according to  claim 42 , wherein the composite metal membrane is formed into tubules by means of a drawing process.  
     
     
         44 . A composite metal membrane produced by the method according to  claim 40 .  
     
     
         45 . The process according to  claim 40 , further comprising providing a precursor for a temporary covering membrane of a base metal alloy or a metal alloy in addition to the precursors for the metal membrane and the membrane support, placing the precursor for the metal membrane between the precursor for the membrane support and the precursor for the covering membrane, producing the metal composite by bonding all three precursors, forming the desired thickness of metal membrane by working the metal composite and then forming the porous structure for the membrane support by dissolving out at least one alloy phase, wherein the temporary covering membrane is completely dissolved away before, at the same time as or after production of the porous structure in the membrane support.  
     
     
         46 . The process according to  claim 1 , further comprising providing a further non-porous precursor for a second membrane support in addition to the precursors for the metal membrane and the membrane support, placing the precursor for the metal membrane between the precursor for the membrane support and the precursor for the second membrane support, forming the metal composite by bonding together all three precursors, forming the desired thickness of the metal membrane by working the metal composite to reduce the thickness thereof and then dissolving out an alloy phase from the membrane support to thereby form the porous structure for the membrane supports.  
     
     
         47 . A composite metal membrane containing a metal membrane on a metallic membrane support with a porous structure, produced by the method according to  claim 45 .  
     
     
         48 . A composite metal membrane produced by the process according to claim  45 .