Wang-Lai Yoon

Preferential CO Oxidation over Ce-Promoted Pt/γ-Al 2 O 3 Catalyst

The effect of Ce promotion over 1wt% Pt/γ-Al2O3 catalysts on the CO conversion and CO2 selectivity was investigated in preferential CO oxidation (PrOx) to reduce the CO concentration less than 10 ppm in excess H2 stream for polymer electrolyte membrane fuel cell (PEMFC). Ce-promoted 1wt% Pt/γ-Al2O3 catalysts were prepared by incipient wetness impregnation method and the loading amount of Pt was fixed at 1wt%. The content of Ce promoter which has excellent oxygen storage and transfer capability due to the redox property was adjusted from 0 to 1.5wt%. Ce-promoted 1wt% Pt/γ-Al2O3 catalysts exhibit high CO conversion and CO2 selectivity at low temperatures below 150℃ due to the improvement of reducibility of surface PtOx species compared with the 1wt% Pt/γ-Al2O3 catalyst without Ce addition. When Ce content was more than 1wt%, the catalytic activity was decreased at over 160℃ in PrOx because of competitive H2 oxidation. As a result, 0.5wt% Ce is optimal content not only to achieve high catalytic activity and good stability at low temperatures below 150℃ in the presence of CO2 and H2O but also to minimize the H2 oxidation at high temperatures.