Characterization of Zr6Nb2O17 synthesized by a peroxo route as a novel solid acid

The impregnation of hydrated zirconia at pH ∼0.5 with a solution of peroxoniobium(V) complex, [Nb2(O2)3]4+, ensuring a ZrO2:Nb2O5 mole ratio of 6:1 followed by calcination at 873 K resulted in the formation of a Zr6Nb2O17 solid solution. The structure of this compound was confirmed by XRD. The surface acidity was investigated by in situ FT-IR spectroscopy using 2,6-dimethylpyridine (lutidine). Zr6Nb2O17 has a sufficient amount of Brønsted acid sites necessary for the stabilization of dispersed Pd(II) species. The potential of the Pd-promoted Zr6Nb2O17 as a catalyst for the reduction of NO with methane was evaluated by studying the reactivity of adsorbed NOx species toward the hydrocarbon.