N-doped activated carbon as support of Pd-Sn bimetallic catalysts for nitrate catalytic reduction

This work studies the catalytic reduction of nitrate using N-doped activated carbon catalysts. Activated carbons were prepared by hydrothermal carbonization (220 °C, 80 % water, 16 h) of garden and park waste and olive stones using (NH4)2SO4 as N source, followed by chemical activation with H3PO4 at 500 °C (N2 atmosphere, 1 h). These were impregnated with Pd and Sn to prepare bimetallic catalysts for nitrate catalytic reduction. N-doping improved the BET surface area up to 1369 m2 g−1 and increased the N content on the catalyst surface to 3 wt%. The N-doped catalysts showed better catalytic performance than the non-doped ones, showing high stability for 100 h on stream, reaching even higher activity than a catalyst supported on a commercial activated carbon. N-doping also showed a positive effect by decreasing NH4+ selectivity. Finally, natural and drinking waters spiked with NO3- were treated in continuous flow, exhibiting the N-doped activated carbon catalysts, prepared from garden and park waste, a high tolerance to ions other than NO3- present in the water solution.