Process for Preparing Palladium Alloy Composite Membranes for Use in Hydrogen Separation, Palladium Alloy Composite Membranes and Products Incorporating or Made from the Membranes

Abstract

The invention is directed to a method for producing Palladium alloy composite membranes that are useful in applications that involve the need to separate hydrogen from a gas mixture. Further, in one embodiment, a Pd alloy composite membrane is realized in which the Pd alloy film is 1 μm or less in thickness and resistant to poisoning by sulfide compounds. Further, the Pd alloy composite membranes are applied to a number of applications, such a fuel reforming.

1 . A method for making a palladium alloy composite membrane comprising: 
 providing a porous substrate with a support surface for supporting a palladium alloy film, wherein said porous substrate has a pore size adjacent to said support surface of less than about 200 nm;    seeding said support surface with palladium crystallites to produce an activated surface;    first plating, over said activated surface, a palladium film;    second plating, over said palladium film, an alloying material other than silver; and    annealing said porous substrate, palladium film, and alloying material so that there is intermetallic diffusion of said alloying material into said palladium film to produce a palladium alloy film over said porous substrate.    
     
     
         2 . A method, as claimed in  claim 1 , wherein: 
 said pore size is less than about 100 nm.    
     
     
         3 . A method, as claimed in  claim 1 , wherein: 
 said pore size is less than about 50 nm.    
     
     
         4 . A method, as claimed in  claim 1 , wherein: 
 said pore size is less than about 20 nm.    
     
     
         5 . A method, as claimed in  claim 1 , wherein: 
 said pore size is greater than about 5 nm.    
     
     
         6 . A method, as claimed in  claim 1 , wherein: 
 said substrate comprises an asymmetric porous substrate with a pore size gradient.    
     
     
         7 . A method, as claimed in  claim 1 , wherein: 
 said step of first plating having a duration that is chosen based on said pore size and a desired palladium alloy film thickness.    
     
     
         8 . A method, as claimed in  claim 1 , wherein: 
 said step of second plating having a duration that is chosen based on said pore size and a desired palladium alloy film thickness.    
     
     
         9 . A method, as claimed in  claim 1 , wherein: 
 said steps of first plating and second plating are performed so as to produce a desired weight percentage for at least one of said palladium and said alloying material.    
     
     
         10 . A method, as claimed in  claim 9 , wherein: 
 said desired weight percentage is chosen based on a desired hydrogen flux for said palladium alloy film.    
     
     
         11 . A method, as claimed in  claim 1 , wherein: 
 said alloying material is copper; and    said steps of first plating and second plating are performed so that said palladium alloy film is about 40% by weight copper.    
     
     
         12 . A method, as claimed in  claim 1 , further comprising: 
 subjecting, after said step of annealing, said porous substrate and said palladium alloy film to an oxidation and reduction.    
     
     
         13 . A method for making a palladium alloy composite membrane comprising: 
 providing a porous substrate with a support surface for supporting a palladium alloy film, wherein said porous substrate has a pore size adjacent to said support surface;    seeding said support surface with palladium crystallites to produce an activated surface;    first plating, over said activated surface, a palladium film;    second plating, over said palladium film, an alloying material other than silver; and    annealing said porous substrate, palladium film, and alloying material so that there is intermetallic diffusion of said alloying material and said palladium film to produce a palladium alloy film over said porous substrate;    wherein said pore size is determinative of a minimum thickness for said palladium alloy film that is substantially free of leaks;    wherein said steps of first plating, second plating and annealing are performed so as to produce a palladium alloy film with a film thickness that is equal or greater than said minimum thickness.    
     
     
         14 . A method, as claimed in  claim 13 , wherein: 
 said palladium alloy film thickness is less than about 10 microns.    
     
     
         15 . A method, as claimed in  claim 13 , wherein: 
 said palladium alloy film thickness is less than about 5 microns.    
     
     
         16 . A method, as claimed in  claim 13 , wherein: 
 said palladium alloy film thickness is less than about 2 microns.    
     
     
         17 . A method, as claimed in  claim 13 , wherein: 
 said palladium alloy film thickness equal to or less than about 1 micron.    
     
     
         18 . A method, as claimed in  claim 13 , wherein: 
 said steps of first plating and second plating are performed so as to produce a desired weight percentage for at least one of said palladium and said alloying material.    
     
     
         19 . A method, as claimed in  claim 18 , wherein: 
 said desired weight percentage is chosen based on a desired hydrogen flux for said palladium alloy film.    
     
     
         20 . A method, as claimed in  claim 13 , further comprising: 
 subjecting, after said step of annealing, said porous substrate and said palladium alloy film to an oxidation and reduction.    
     
     
         21 . A method, as claimed in  claim 13 , wherein: 
 said step of providing comprises providing an oxide ceramic substrate.    
     
     
         22 . A method, as claimed in  claim 13 , wherein: 
 said step of providing comprises providing a non-oxide ceramic substrate.    
     
     
         23 . A method, as claimed in  claim 13 , wherein: 
 said step of providing comprises providing a sintered/porous metal substrate.    
     
     
         24 . A method, as claimed in  claim 13 , wherein: 
 said step of providing comprises providing a multi-layer substrate with a sintered/porous metal layer and a ceramic layer, wherein said support layer comprises said ceramic layer.    
     
     
         25 . A method, as claimed in  claim 13 , wherein: 
 said step of providing comprises providing an asymmetric porous substrate with a pore size gradient.    
     
     
         26 . A method, as claimed in  claim 13 , wherein: 
 said alloying material is selected from Groups VIII and IB.    
     
     
         27 . A method for making a palladium alloy composite membrane comprising: 
 providing a porous substrate with a support surface for supporting a palladium alloy film;    seeding said support surface with palladium crystallites to produce an activated surface;    first plating, over said activated surface, a palladium film;    second plating, over said palladium film, an alloying material;    annealing said porous substrate, palladium film, and alloying material so that there is intermetallic diffusion of said alloying material and said palladium film to produce a palladium alloy film over said porous substrate; and    subjecting, after said step of annealing, said porous substrate and said palladium alloy film to an oxidation and reduction.    
     
     
         28 . A method, as claimed in  claim 27 , wherein: 
 said step of providing comprises providing a porous substrate that has a pore size adjacent to said support surface of less than about 200 nm.    
     
     
         29 . A method, as claimed in  claim 27 , wherein: 
 said step of providing comprises providing an asymmetric porous substrate with a pore size gradient.    
     
     
         30 . A method, as claimed in  claim 27 , wherein: 
 said porous substrate has a pore size adjacent to said support surface and said pore size is determinative of a minimum thickness for said palladium alloy film that is substantially free of leaks; and    said steps of first plating, second plating and annealing are performed so as to produce a palladium alloy film with a film thickness that is equal to or greater than said minimum thickness.    
     
     
         31 . A method, as claimed in  claim 27 , wherein: 
 said step of providing comprises cleaning said surface prior to said step of seeding.    
     
     
         32 . A method,as claimed in  claim 27 , wherein: 
 said step of providing comprises shaping said porous substrate.    
     
     
         33 . A method, as claimed in  claim 27 , wherein: 
 said step of providing comprises sealing a surface of said porous substrate other than said support surface.    
     
     
         34 . A palladium alloy composite membrane comprising: 
 a porous substrate having a support surface; and    a palladium alloy film, other than a palladium-silver alloy film, bonded to said support surface of said porous substrate;    wherein said palladium alloy film has a thickness of less than about 10 microns.    
     
     
         35 . A palladium alloy composite membrane, as claimed in  claim 34 , wherein: 
 said thickness is less than about 5 microns.    
     
     
         36 . A palladium alloy composite membrane, as claimed in  claim 34 , wherein: 
 said thickness is less than about 2 microns.    
     
     
         37 . A palladium alloy composite membrane, as claimed in  claim 34 , wherein: 
 said thickness is less than about 1.5 microns.    
     
     
         38 . A palladium alloy composite membrane, as claimed in  claim 34 , wherein: 
 said porous substrate comprises an asymmetric porous substrate with a pore size gradient.    
     
     
         39 . A palladium alloy composite membrane, as claimed in  claim 34 , wherein: 
 said palladium alloy film having a desired weight percentage for at least one of said palladium and an alloy material, said weight percentage being chosen based upon a desired hydrogen flux.