Selective methanation reactor for reducing carbon monoxide in a reformate stream

Abstract

A methanation reactor to reduce carbon monoxide concentration in a reformate stream. The reactor includes a noble metal catalyst supported by a ceramic support such that the reactor preferentially converts of carbon monoxide via methanation over that of carbon dioxide. In one embodiment, the ceramic support is alumina with a coating of silica deposited on the alumina to increase the support surface acidity and consequent carbon monoxide conversion. The purpose of the abstract is to enable the United States Patent and Trademark Office and the public generally to determine from a cursory inspection the nature and gist of the technical disclosure, and is not to be used for interpreting the scope of the claims.

What is claimed is:  
     
         1 . A methanation reactor comprising: 
 a reformate stream inlet;    a reformate stream outlet in fluid communication with said inlet;    a flowpath disposed between said inlet and outlet; and    a rhodium-based catalyst disposed on a silica-coated alumina support, said support disposed within said flowpath.    
     
     
         2 . A device for the removal of carbon monoxide from a reformate stream, said device comprising a reactor, said reactor comprising: 
 a porous ceramic support defining a surface acidity;    a coating configured to increase said surface acidity;    a noble metal catalyst coupled to at least one of said support or said coating; and    a flowpath configured to place said reformate stream in fluid communication with at least said noble metal catalyst such that carbon monoxide conversion in said reactor is greater than if said coating were not present.    
     
     
         3 . A device according to  claim 2 , wherein said reactor is configured to operate in a temperature regime such that selectivity for carbon monoxide in said reactor is at least 70 percent and conversion of carbon monoxide is at least 30 percent.  
     
     
         4 . A device according to  claim 2 , wherein said noble metal comprises rhodium.  
     
     
         5 . A device according to  claim 2 , wherein said rhodium is present in said reactor in a concentration of up to approximately two percent.  
     
     
         6 . A device according to  claim 5 , wherein said rhodium concentration is approximately one percent.  
     
     
         7 . A device according to  claim 2 , wherein said support is alumina.  
     
     
         8 . A device according to  claim 7  wherein said coating is silica.  
     
     
         9 . A device according to  claim 2 , wherein said reactor is configured to operate in a temperature regime such that said selectivity is at least 80 percent and said conversion is at least 30 percent.  
     
     
         10 . A device according to  claim 2 , wherein said noble metal comprises ruthenium.  
     
     
         11 . A device according to  claim 2 , further comprising a reformer in fluid communication with said reactor, said reformer configured to convert raw fuel into said reformate stream.  
     
     
         12 . A device according to  claim 11 , further comprising: 
 a fuel supply and an oxygen supply, together configured to provide fuel and oxygen to said reformer; and    a fuel cell configured to receive a hydrogen-rich portion of said reformats stream that has passed through said reactor.    
     
     
         13 . A device according to  claim 12 , wherein said fuel cell is a proton exchange membrane fuel cell.  
     
     
         14 . A device according to  claim 12 , wherein said fuel cell system is part of a vehicle such that said fuel cell is a source of motive power.  
     
     
         15 . A device according to  claim 14 , wherein said vehicle comprises: 
 a platform configured to carry said source of motive power;    a drivetrain rotatably responsive to output from said source of motive power, said drivetrain connected to said platform; and    a plurality of wheels connected to said drivetrain.    
     
     
         16 . A device according to  claim 2 , further comprising a preferential oxidation system placed in fluid communication with said reactor, thereby effecting addition carbon monoxide removal from said reformate stream.  
     
     
         17 . A device according to  claim 2 , further comprising a palladium-based permeation membrane placed in fluid communication with said reactor, thereby effecting addition carbon monoxide removal from said reformate stream.  
     
     
         18 . A device for the removal of carbon monoxide from a reformate stream, said device comprising: 
 a ceramic support;    a noble metal catalyst coupled to said support; and    a flowpath configured to place said reformate stream in fluid communication with at least said noble metal catalyst, wherein said support, noble metal catalyst and said flowpath are configured such that while operating in a temperature regime not in excess of 260 degrees Celsius, selectivity for carbon monoxide in said reactor is at least approximately 60 percent.    
     
     
         19 . A device according to  claim 18 , wherein said ceramic is zirconia.  
     
     
         20 . A device according to  claim 19 , wherein said noble metal comprises rhodium.  
     
     
         21 . A device according to  claim 19 , wherein said noble metal comprises ruthenium.  
     
     
         22 . A method of delivering fuel to a fuel cell system, said method comprising: 
 configuring a fuel delivery system to include a fuel supply and oxygen supply;    fluidly connecting a fuel processing system to said fuel delivery system, said fuel processing system comprising: 
 a reformer to evaporate a mixture of fuel and oxygen coming from said fuel delivery system; and  
 a methanation reactor for the removal of carbon monoxide from a reformate stream produced by said reformer, said reactor comprising: 
 a porous ceramic support defining a surface acidity;  
 a coating configured to increase said surface acidity;  
 a noble metal catalyst coupled to at least one of said support or said coating; and  
 a flowpath configured to place said reformate stream in fluid communication with at least said noble metal catalyst such that carbon monoxide conversion in said reactor is greater than if said coating were not present;  
 
   introducing fuel and oxygen to create a fuel-oxygen mixture;    heating said fuel-oxygen mixture in said reformer such that said reformate stream is produced;    purifying said reformate stream in said reactor; and    transporting a hydrogen-rich portion of said reformate stream to said fuel cell.    
     
     
         23 . A method according to  claim 22 , wherein said reactor is configured to operate in a temperature regime such that selectivity for carbon monoxide in said reactor is at least 70 percent and conversion of carbon monoxide is at least 30 percent.  
     
     
         24 . A method according to  claim 22 , wherein said noble metal comprises rhodium.  
     
     
         25 . A method according to  claim 24 , wherein said support is alumina.  
     
     
         26 . A method according to  claim 25  wherein said coating is silica.  
     
     
         27 . A method of purifying a methanol reformate stream, said method comprising: 
 configuring a reformer to evaporate a mixture of fuel and oxygen, said evaporated mixture defining said reformate stream;    fluidly connecting a methanation reactor to said reformer for the removal of carbon monoxide from said reformate stream, said reactor comprising: 
 a porous ceramic support defining a surface acidity;  
 a coating configured to increase said surface acidity;  
 a noble metal catalyst coupled to at least one of said support or said coating; and  
 a flowpath configured to place said reformate stream in fluid communication with at least said noble metal catalyst such that carbon monoxide conversion in said reactor is greater than if said coating were not present;  
   evaporating said mixture of fuel and oxygen such that said reformate stream is produced; and    exposing at least a portion of said reformate stream to said reactor such that at least a portion of carbon monoxide is removed from said reformate stream.