Systems and methods for steam reforming

Abstract

One embodiment of the present invention is a unique method for operating a fuel cell system. Another embodiment is a unique system for reforming a hydrocarbon fuel. Another embodiment is a unique fuel cell system. Other embodiments include apparatuses, systems, devices, hardware, methods, and combinations for fuel cell systems and steam reforming systems. Further embodiments, forms, features, aspects, benefits, and advantages of the present application will become apparent from the description and figures provided herewith.

We claim: 
     
         1 . A system for steam reforming a hydrocarbon fuel, comprising:
 a source of fuel;   a fuel cell stack;   a catalyst consisting essentially of platinum and ruthenium as catalytically active materials, wherein the platinum content by weight is less than the ruthenium content of the catalyst, and wherein the catalyst is configured for self-cleaning of sulfur compounds when performing steam reforming using a low-sulfur content hydrocarbon fuel; and   a reformer comprising:
 a fuel inlet in fluid communication with the source of fuel and configured to receive hydrocarbon fuel from the source of fuel; 
 a fuel outlet in fluid communication with the fuel cell stack and configured to provide reformed hydrocarbon fuel to the fuel cell stack; and 
 a catalytic reactor having a plurality of surfaces, wherein the plurality of surfaces have the catalyst disposed thereon, and wherein the catalyst is configured to: 
 reform a high-sulfur-content hydrocarbon fuel received from the source of fuel with at least steam for a first period of time; and 
 reform a low-sulfur-content hydrocarbon fuel received from the source of fuel with at least steam for a second period of time whereby the catalyst, using the low-sulfur content hydrocarbon fuel, self-cleans of sulfur compounds that may be present from poisoning by sulfur exposure during the reforming of the high-sulfur-content hydrocarbon fuel. 
   
     
     
         2 . The system of  claim 1 , wherein the platinum content of the catalyst is a minimum platinum content consistent with the desired level of sulfur resistance. 
     
     
         3 . The system of  claim 3 , wherein the ruthenium content of the catalytically active materials is approximately 75% to 99.99% by weight; and wherein the platinum content of the catalytically active materials is approximately 0.01% to 25% by weight. 
     
     
         4 . The system of  claim 1 , wherein the catalyst is supported on a carrier. 
     
     
         5 . The system of  claim 4 , wherein the carrier includes a refractory oxide, including at least one of silica, alumina, zirconia and tungsten oxide. 
     
     
         6 . The system of  claim 5 , wherein the carrier includes mixed refractory oxides having at least two cations. 
     
     
         7 . The system of  claim 5 , wherein the carrier includes alumina, and wherein the alumina is stabilized by at least one of baria, ceria, lanthana and magnesia. 
     
     
         8 . The system of  claim 1  configured to activate the catalyst by heating the catalyst in hydrogen and/or another reducing gas. 
     
     
         9 . The system of  claim 1 , wherein at least some of the platinum and the ruthenium of the catalyst is in the form of a platinum-ruthenium alloy. 
     
     
         10 . The system of  claim 1 , wherein the catalytic reactor includes a tube having an axis and a plurality of channels extending parallel to the axis, wherein the plurality of channels comprise the plurality of surfaces. 
     
     
         11 . The system of  claim 10  wherein a number of the plurality of channels is in the range of 200 to 1200 channels per square inch when viewed in a direction along the axis. 
     
     
         12 . The system of  claim 1 , wherein the catalyst is configured for self-cleaning within a period of 50 hours or less to achieve a methane conversion of greater than about 90% of an equilibrium conversion when using natural gas as the hydrocarbon fuel. 
     
     
         13 . The system of  claim 1 , wherein the catalyst is configured for self-cleaning within a period of 40 hours or less to achieve a methane conversion of greater than about 90% of an equilibrium conversion when using natural gas as the hydrocarbon fuel. 
     
     
         14 . The system of  claim 1 , wherein the catalyst is configured for self-cleaning within a period of 25 hours or less to achieve a methane conversion of greater than about 90% of an equilibrium conversion when using natural gas as the hydrocarbon fuel. 
     
     
         15 . A fuel cell system, comprising:
 a fuel cell stack;   a source of hydrocarbon fuel;   a reformer having a fuel inlet in fluid communication with the source of hydrocarbon fuel, a fuel outlet in communication with the fuel cell stack, and a plurality of reforming channels fluidically connecting the fuel inlet and the fuel outlet; and   a catalyst disposed on at least some of the surfaces of the reforming channels, said catalyst comprising platinum and ruthenium as catalytically active materials wherein the ruthenium content by weight is at least three times greater than the platinum content.   
     
     
         16 . The fuel cell system of  claim 15 , wherein the ruthenium content is approximately at least five times greater by weight than the platinum content. 
     
     
         17 . The system of  claim 15 , wherein the ruthenium content of the catalytically active materials is approximately 75% to 99.99% by weight; and wherein the platinum content of the catalytically active materials is approximately 0.01% to 25% by weight. 
     
     
         18 . A reformer configured to:
 receive a catalyst;   receive a high-sulfur hydrocarbon fuel;   reform with the catalyst the high-sulfur-content hydrocarbon fuel with at least steam;   receive a low-sulfur hydrocarbon fuel; and   reform the low-sulfur-content fuel with the catalyst such that the catalyst, using the low-sulfur content fuel, desorbs sulfur compounds which may be bound to the catalyst that may be present from poisoning by sulfur exposure during the reforming of the high-sulfur-content hydrocarbon fuel.   
     
     
         19 . The reformer of  claim 18  comprising a catalytic reactor, wherein the catalytic reactor includes a tube having an axis and a plurality of channels extending parallel to the axis, wherein the catalyst is disposed on the plurality of channels. 
     
     
         20 . The reformer of  claim 18 , wherein the catalyst consists essentially of platinum and ruthenium as catalytically active materials.