PEM fuel cells fed by hydrogen from ethanol dehydrogenation reaction: unveiling the poisoning mechanisms of the by-products

ABSTRACT This work investigates the influence of hydrogen contaminated with the main by-products of the ethanol dehydrogenation reaction, i.e. ethyl acetate, acetaldehyde and unreacted ethanol, on the anode performance of a proton exchange membrane fuel cell employing different catalysts, aiming at understanding and minimizing the efficiency losses caused by these molecules. Pt-W/C and Pt-Sn/C catalysts were investigated, having Pt/C as reference, which were chosen due their ability to oxidize small organic molecules without breaking of C-C bonds and without producing strong poisoning intermediates (i.e. less prone to have its active sites blocked by side reactions). Results evidence that anode catalysts that presents lower activity for small organic molecules oxidation and/or weaker reactant adsorption, which is the case of Pt-Sn/C, are best suited for PEMFC systems directly fed by hydrogen from ethanol dehydrogenation reaction. It is also found that crossover of the considered by-products from the anode towards the cathode also has a major impact on fuel cell efficiency losses.