Use Of Anode Catalyst Layer

Abstract

A method of operating a fuel cell having an anode, a cathode and a polymer electrolyte membrane disposed between the anode and the cathode, includes feeding the anode with an impure hydrogen stream having low levels of carbon monoxide up to 5 ppm, and wherein the anode includes an anode catalyst layer including a carbon monoxide tolerant catalyst material, wherein the catalyst material includes: (i) a binary alloy of PtX, wherein X is a metal selected from the group consisting of rhodium and osmium, and wherein the atomic percentage of platinum in the alloy is from 45 to 80 atomic % and the atomic percentage of X in the alloy is from 20 to 55 atomic %; and (ii) a support material on which the PtX alloy is dispersed; wherein the total loading of platinum group metals (PGM) in the anode catalyst layer is from 0.01 to 0.2 mgPGM/cm2.

What is claimed: 
     
         1 . A method of operating a fuel cell comprising an anode, a cathode and a polymer electrolyte membrane disposed between the anode and the cathode, wherein said method comprises feeding the anode with an impure hydrogen stream comprising carbon monoxide in an amount of between 0.2 ppm to 2 ppm, and wherein the anode comprises an anode catalyst layer comprising a carbon monoxide tolerant catalyst material, wherein the catalyst material comprises:
 (i) a binary alloy of PtX, wherein X is rhodium, and wherein the atomic percentage of platinum in the alloy is from 45 to 80 atomic % and the atomic percentage of X in the alloy is from 20 to 55 atomic %; and   (ii) a support material on which the PtX alloy is dispersed;   wherein the total loading of platinum group metals (PGM) in the anode catalyst layer is from 0.01 to 0.2 mgPGM/cm 2 ,
 wherein the fuel cell produces stable voltages when the anode is fed an impure catalyst stream comprising 2 ppm of carbon monoxide. 
   
     
     
         2 . The method according to  claim 1 , wherein the atomic percentage of Pt in the binary alloy is from 50 to 75 atomic % and the atomic percentage of X is from 25 to 50 atomic %. 
     
     
         3 . The method according to  claim 1 , wherein the amount of platinum in the supported catalyst is 10-50 wt % of the total weight of the binary alloy plus support material. 
     
     
         4 . The method according to  claim 1 , wherein the anode further comprises a second catalyst. 
     
     
         5 . The method according to  claim 4 , wherein the second catalyst is an oxygen evolution catalyst. 
     
     
         6 . The method according to  claim 2 , wherein the atomic percentage of Pt in the binary alloy is from 50 to 75 atomic % and the atomic percentage of X is from 25 to 50 atomic %. 
     
     
         7 . The method according to  claim 2 , wherein the amount of platinum in the supported catalyst is 10-50 wt % of the total weight of the binary alloy plus support material. 
     
     
         8 . The method according to  claim 2 , wherein the anode further comprises a second catalyst. 
     
     
         9 . The method according to  claim 3 , wherein the anode further comprises a second catalyst. 
     
     
         10 . The method according to  claim 8 , wherein the second catalyst is an oxygen evolution catalyst. 
     
     
         11 . The method according to  claim 9 , wherein the second catalyst is an oxygen evolution catalyst.