Promotion of Pt/γ-Al2O3 by new pretreatment for low-temperature preferential oxidation of CO in H2 for PEM fuel cells

The hydrogen-rich reformate used as a feed to polymer electrolyte fuel cells (PEFC) must contain less than 10 ppm CO since it poisons the Pt anode. The concentration of CO leaving the water-gas shift reactor is typically around 1 mol%, which is set by thermodynamic equilibrium. One method to remove the CO is by preferential oxidation (PROX) using O-2 over a (typically) Pt catalyst while minimizing the amount of H-2 oxidized. The activity and selectivity of this reaction were improved by a new pretreatment method for a 5 wt% Pt/gamma-Al2O3 catalyst. The pretreatment involved saturating the reduced catalyst with water and allowing it to vaporize during reduction. The improvement is attributed to a reduction in size of the metallic Pt particles as measured by XRD and TEM. (C) 2002 Elsevier Science (USA).