Electro-reduction of nitrogen oxides using steam electrolysis in a proton conducting solid electrolyte membrane reactor (H+-SEMR)

A double chamber SrCe0.95Yb0.05O3 − a proton conducting membrane reactor was used in order to explore N2O and NO cathodic reduction, over Pd cathodes, by hydrogen generated from steam electrolysis at the anode. Non-Faradaic enhancement of N2O decomposition was observed at cathodic overpotentials, and |Λ| values above unity were achieved. Electrochemically transferred protons not only liberated the active sites from oxygen ad-atoms but also activated inactive, at open circuit, sites to adsorb and dissociate N2O. In the NO-containing reactant mixtures the NO reduction rate was always negligible at open circuit since Pd was essentially inactive towards NO dissociation. Nevertheless, Pd became active at cathodic overpotentials, and |Λ| values equal to unity revealed a Faradaic enhancement according to the “decomposition” mechanism. In presence of C3H8 and O2 data suggested a “reduction” type of mechanism.