Use of sulfur-containing fuels for direct oxidation fuel cells

Abstract

The invention relates to a solid oxide fuel cell which comprises a solid electrolyte comprised of an electronic insulator which allows transfer of anions, a ceramic-metal composite anode and, a cathode. The fuel cell also comprises a sulfur-containing hydrocarbon fuel having a sulfur content of from about 1 ppm to about 5000 ppm and an oxygen source. The invention further relates to a process of producing electrical energy with the fuel cell and a process of restoring the operability of a fuel cell that was deactivated by sulfur poisoning. The invention also relates to a method for preparation of a porous cermet as a direct-oxidation anode with supported electrolyte structure for a solid-oxide fuel cell using a nickel cermet. The nickel cermet is leached to remove at least part of the nickel, thereby producing a porous oxide. The resulting porous oxide is then impregnated, preferably with a salt of copper, which is calcined to CuO, then reduced to elemental copper. The resulting copper cermet or copper-nickel alloy cermet can be used as the direct-oxidation anode. The starting material for the nickel cermet is preferably a tape formed from a slurry comprising NiO and a ceramic powder comprising YSZ. This tape is combined into an assemblage with one or two additional tapes cast from a slurry comprising a ceramic powder. The invention further relates to a solid-oxide fuel cell comprising an anode material with supported electrolyte structure made by this method and a process for producing electrical energy using this fuel cell.

1 - 50 . (canceled)  
   
   
       51 . A method of making a solid oxide fuel cell trilaminate structure comprising a perforated layer, an anode, and an electrolyte comprising: 
 preparing a first anode tape of a first tape casting formulation comprising a ceramic powder containing at least YSZ, and a pore former;    preparing a second electrolyte tape of a second tape casting formulation comprising at least YSZ;    forming a laminate comprised of the first anode tape and the second electrolyte tape;    preparing a third tape casting formulation in the form of a slurry comprising a binder, a carrier and a ceramic powder, the coefficient of thermal expansion of the ceramic powder, when sintered, being compatible with that of sintered YSZ;    applying the slurry of third tape casting formulation to a supporting substrate and forming the slurry into a third tape, the thickness of the third tape being relatively greater than the thickness of said second tape;    perforating the third tape, thereby forming at least one aperture through the thickness of the tape; and    superposing the perforated third tape on the laminate in contact with the first anode tape to form a trilaminate structure; sintering the trilaminate structure to form a perforated third layer, a porous anode layer comprising at least YSZ, and a relative dense electrolyte layer comprising at least YSZ;    impregnating the porous anode layer with an aqueous solution containing a salt of an electronically conductive material to form an impregnated trilaminate structure;    calcining the impregnated trilaminate structure at a temperature sufficient to form an oxide of the electronically conductive material; and    reducing the oxide of the electronically conductive material to form a trilaminate structure comprising a perforated layer a porous anode comprising at least YSZ and the electronically conductive material, and an electrolyte comprising at least YSZ.    
   
   
       52 . The method of  claim 51 , wherein the at least one aperture in the third tape has a periphery with a continuously curved outline.  
   
   
       53 . (canceled)  
   
   
       54 . The method of  claim 51 , wherein the electronically conductive material is selected from the group consisting of nickel, copper, ceria, and combinations thereof.  
   
   
       55 . The method of  claim 54 , wherein the electronically conductive material is copper.  
   
   
       56 . The method of  claim 54 , wherein the electronically conductive material is a combination of copper and ceria.  
   
   
       57 . The method of  claim 51 , wherein calcining is conducted at a temperature of at least 600° C.  
   
   
       58 . The method of  claim 51 , wherein sintering is conducted at a temperature of about 1,500° C. for about two hours.  
   
   
       59 . The method of  claim 51 , wherein reducing the oxide of the electronically conductive material is carried out by reduction in hydrogen gas at a temperature of about 500° C.  
   
   
       60 . A solid oxide fuel cell trilaminate anode structure comprising: 
 a perforated ceramic layer comprising at least a ceramic material having a coefficient of thermal expansion, when sintered, compatible with that of sintered YSZ;    a porous anode layer positioned adjacent the perforated ceramic layer and comprising a porous ceramic containing at least YSZ, and an electronically-conductive material dispersed at least partially within the pores; and    a relatively dense electrolyte layer comprising at least YSZ positioned adjacent the porous anode layer.    
   
   
       61 . The trilaminate anode structure of  claim 60 , wherein the electronically conductive material is selected from the group consisting of nickel, copper, ceria, and combinations thereof.  
   
   
       62 . The trilaminate anode structure of  claim 61 , wherein the electronically conductive material is copper.  
   
   
       63 . The trilaminate anode structure of  claim 61 , wherein the electronically conductive material is a combination of copper and ceria.  
   
   
       64 . The trilaminate anode structure of  claim 60 , wherein the ceramic material in the perforated ceramic layer is selected from the group consisting of YSZ, MgAlO 2 , and combinations thereof.  
   
   
       65 . The trilaminate anode structure of  claim 60 , wherein the perforated ceramic layer has a thickness within the range of from about 300 μm and about 5,000 μm.  
   
   
       66 . The trilaminate anode structure of  claim 60 , wherein the porous anode layer has a thickness within the range of from about 100 μm and about 1,000 μm.  
   
   
       67 . The trilaminate anode structure of  claim 60 , wherein the electrolyte layer has a thickness less than about 100 μm.  
   
   
       68 . A solid oxide fuel cell comprising: 
 the trilaminate anode structure of  claim 60;  and    a cathode positioned adjacent the relatively dense electrolyte layer.    
   
   
       69 . A method of making a making a solid oxide fuel cell trilaminate structure comprising a perforated layer, an anode, and an electrolyte comprising: 
 forming an first anode layer;    forming a second electrolyte layer comprised of a ceramic electrolyte material, and positioning the second electrolyte layer adjacent the first anode layer;    forming a third layer on a side of the first anode layer opposite the second electrolyte layer, the third layer comprising a binder, a carrier and a ceramic powder, the coefficient of thermal expansion of the ceramic powder, when sintered, being compatible with that of the ceramic electrolyte material, when sintered;    perforating the third layer, thereby forming at least one aperture through the thickness of the third layer;    sintering the third layer, first anode layer and second electrolyte layer to form a perforated third layer, a porous anode layer, and a relative dense electrolyte layer;    impregnating the porous anode layer with an aqueous solution containing a salt of an electronically conductive material; and    forming a solid oxide fuel cell trilaminate structure.    
   
   
       70 . The method of  claim 69 , wherein the at least one aperture in the third layer has a periphery with a continuously curved outline.  
   
   
       71 . The method of  claim 69 , wherein the electronically conductive material is selected from the group consisting of nickel, copper, ceria, and combinations thereof.