CONICET | Buscador de Institutos y Recursos Humanos

The low-temperature proton exchange membrane fuel cell (PEMFC) has been largely studied and developed during the last two decades specially for its application in mobile sources. PEMFC operation requires CO-free hydrogen: if CO concentration is higher than 10-20 ppm, the anode is irreversibly poisoned and the fuel cell efficiency decreases. Therefore, hydrogen produced from steam reforming of hydrocarbons or alcohols must be purified before entering the PEMFC. The preferential oxidation of CO (COPROX) is the simplest and the least expensive ultimate purification technique. In this work, a series of CuO-CeO2 catalysts prepared by the urea method was tested in the preferential oxidation of CO in the presence of H2 (COPROX). A laboratory fixed bed reactor and a reaction mixture consisting of 90%H2, 2,25%CO, 2,25 %O2, and N2 as balance were used to study the influence of the reaction temperature in the range from 100 to 260 ºC on the catalytic activity and selectivity. The general behavior is similar for all samples. The CO conversion increases with temperature until a maximum, whose temperature depends on the copper content of the sample, is reached. Above this point, the hydrogen oxidation becomes very fast; therefore, a greater quantity of the available oxygen reacts with hydrogen and the CO conversion decreases. It can be observed that the CO optimum conversion shifts to lower temperatures as the copper content of the sample increases. Previous studies of CO oxidation in absence of hydrogen confirm this behaviour: as copper content increases, the light-off temperature for the CO conversion decreases. These CuO-CeO2 catalysts have shown to be very active and even more selective towards CO oxidation than commercial Pt-based catalysts. In the COPROX reactor, CuO-CeO2 catalysts were able to reduce CO concentration from 2.25% to 0.30% with a hydrogen loss lower than 1%.

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