New layered double hydroxides with the hydrotalcite structure containing Ni(II) and V(III)

Abstract

Layered double hydroxides (LDH) with the hydrotalcite-like structure, but containing Ni(II) and V(III) cations in the layers, have been prepared by the constant pH method. Characterization by elemental chemical analysis, powder X-ray diffraction, differential thermal analysis, thermogravimetric analysis, FT-IR spectroscopy, temperature-programmed reduction and specific surface area assessment indicates the formation of well crystallized materials after hydrothermal treatment, without significant oxidation of V(III) species, and with interlayer, flat-oriented, carbonate anions. Reduction in H 2 takes place in a single step at ca. 400 °C [Ni(II)→Ni(0)]; V(III) is not reduced. On calcination in air, Ni 2 V 3 O 8 is formed, together with NiO, but crystallization is only evident after calcination at 750 °C. No major difference was found between samples with Ni:V molar ratios close to 2 or 4.