Decavanadate-intercalated Ni–Al hydrotalcites as precursors of mixed oxides for the oxidative dehydrogenation of propane

Two nickel–aluminum hydrotalcite type precursors were synthesized with molar ratio Ni/Al = 3, using hydroxyl and carbonate as compensation anions. These precursors were intercalated by 30% (theoretical) decavanadate anion. The catalysts were obtained after calcination at 550 °C and their performance was evaluated in propane oxidative dehydrogenation at 400 °C using space velocities of 100, 150, 200 and 400 ml g−1 min−1 under conditions of oxygen deficiency and oxygen excess. Catalysts derived from nickel–aluminum-hydroxyl precursors attained an excellent performance under oxygen deficiency conditions promoting high propene selectivity and conversion. Under oxygen excess conditions the catalyst was more active but its selectivity was lower. Vanadium-containing catalysts showed improved selectivity under this operation condition. The formation of the hydrotalcite phase in precursors and mixed oxides in the catalysts was evidenced by X-ray diffraction (XRD). Analyses of textural and reduction properties were carried-out with nitrogen adsorption and temperature programmed reduction techniques respectively. Structural studies were performed by X-ray absorption spectroscopy for materials that showed best performance in the oxidative dehydrogenation reaction.

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► Ni–V mixed oxides catalysts from Ni–Al hydrotalcite type precursors with decavanadate.
► Decavanadate incorporation depends on anion type in hydrotalcite-precursor.
► Partial aluminum substitution in hydrotalcite layers.
► Catalysts with pyro- and ortho-vanadate of nickel and nickel oxide.
► Hydroxyl anion precursor produced the catalyst with better selectivity to propene.