Sulfur-resistant composite metal membranes

Abstract

The invention provides thin, hydrogen-permeable, sulfur-resistant membranes formed from palladium or palladium-alloy coatings on porous, ceramic or metal supports. Also disclosed are methods of making these membranes via sequential electroless plating techniques.

1 . A sulfur-resistant palladium alloy composite membrane comprising:
 a palladium layer that makes contact with a surface of a porous substrate;   a second layer comprising a second layer material that makes contact with the palladium layer, wherein the second layer material is selected from the group consisting of copper, silver and gold; and   a third layer comprising a third layer material that makes contact with the second layer, wherein the third layer material is selected from the group consisting of copper, gold and silver and wherein the second layer material and the third layer material are different.   
     
     
         2 . The membrane of  claim 1 , wherein the second layer material is copper and the third layer material is selected from the group consisting of gold and silver. 
     
     
         3 . The membrane of  claim 1 , wherein the second layer material is gold and the third layer material is selected from the group consisting of silver and copper. 
     
     
         4 . The membrane of  claim 1 , wherein the second layer material is silver and the third layer material is selected from the group consisting of gold and copper. 
     
     
         5 . The membrane of  claim 1 , wherein the porous substrate is selected from the group consisting of an oxide ceramics, alumina, titania, zirconia, non-oxide ceramics, SiC, SiN, sintered metal, porous metal, stainless steel, nickel, sintered metals with ceramic surfaces, porous metals with ceramic surfaces, and porous vycor glass. 
     
     
         6 . The membrane of  claim 1 , wherein the porous substrate is tubular. 
     
     
         7 . The membrane of  claim 1 , wherein the porous substrate is planar. 
     
     
         8 . The membrane of  claim 1 , wherein the porous substrate is a stainless steel support. 
     
     
         9 . The membrane of  claim 8  further comprising a porous ZrO 2  coating on the stainless steel support. 
     
     
         10 . The membrane of  claim 1 , further comprising a sealant. 
     
     
         11 . The membrane of  claim 1 , wherein a thickness of the palladium first layer is between about 1 μm and about 7 μm. 
     
     
         12 . The membrane of  claim 1 , wherein the second material layer is gold and a thickness of the second layer is between about 1 μm and about 7 μm. 
     
     
         13 . The membrane of  claim 1 , wherein a pore size of the porous substrate is between 20-80 nm. 
     
     
         14 . A sulfur-resistant palladium-gold alloy composite membrane comprising:
 a palladium first layer that makes contact with a surface of a porous substrate, wherein the palladium-gold alloy, wherein a thickness of the palladium first layer is between about 1 μm and about 7 μm; and   a gold second layer that makes contact with the palladium first layer, wherein a thickness of the gold second layer is between about 1 μm and about 7 μm.   
     
     
         15 . The membrane of  claim 14 , wherein a thickness of the palladium-gold alloy is between about 2 μm and about 10 μm. 
     
     
         16 . The membrane of  claim 14 , wherein a thickness of the palladium-gold alloy is between about 2 μm and about 5 μm. 
     
     
         17 . The membrane of  claim 14 , further comprising:
 a third layer that makes contact with the second layer, wherein the third layer comprising a third layer material selected from the group consisting of copper and silver.   
     
     
         18 . The membrane of  claim 14 , wherein mass percent of the gold in the palladium-gold alloy is between 5 and 50 mass percent. 
     
     
         19 . The membrane of  claim 14 , wherein the porous substrate is tubular. 
     
     
         20 . The membrane of  claim 14 , wherein the porous substrate is planar. 
     
     
         21 . A sulfur-resistant a palladium alloy composite membrane comprising:
 a porous substrate; and   a palladium alloy in contact with at least one surface of the porous substrate, comprising palladium; a second material selected from the group consisting of copper, silver and gold; and a third material, selected from the group consisting of copper, gold and silver;   wherein the second material and the third material are different from each other, and wherein a thickness of the palladium alloy is between about 2 μm and about 10 μm.