Selective oxidation of CO in hydrogen under fuel cell operating conditions

Five catalysts (Au/MnOx, Pt/Vulcan-XC-72, Pt/SnO2/Vulcan-XC-72, Ir/carbon, and Ir/CoOx-Al2O3/carbon) were investigated as CO selective oxidation catalysts with O-2 under conditions similar to that of an operating fuel cell (76 degreesC, high humidity). This investigation was done to study the possibility of integrating a CO removal reactor into a fuel cell stack. The Ir/CoOx-Al2O3/carbon catalyst was the superior catalyst for CO selective oxidation with the highest CO conversion and selectivity among the catalysts evaluated. A nearly 100% CO conversion occurred with the Ir/CoOx-Al2O3/carbon catalyst at O-2/CO = 1.5. Although the Au/MnOx catalyst had high activity and selectivity for CO oxidation tinder dry conditions, its activity decayed dramatically due to instability of MnOx in the presence of water vapor and hydrogen. (C) 2001 The Electrochemical Society.