Freeze-Dried Precursor-Based Synthesis of Nanostructured Cobalt−Nickel Molybdates Co1-xNixMoO4

Abstract

A simple processing route to nanostructured mixed cobalt−nickel molybdates, Co1-xNixMoO4 (0 ≤ x ≤ 1), has been developed. It is based on the use of precursors resulting from the freeze-drying of aqueous solutions of the appropriate common metal salts. Thermal decomposition of amorphous freeze-dried powders at low temperatures produces the nanostructured mixed oxides. A study of the influence of the preparative variables on the outcomes of this procedure is presented. The resulting materials have been characterized by X-ray powder diffraction, elemental analysis, scanning electron microscopy, thermogravimetry under oxygen flow, and physisorption measurements. Co1-xNixMoO4 grains (obtained by calcination below 773 K) are aggregates of nanometric particles (with diameters typically around 30−40 nm) and have relatively high specific surface areas (20−40 m2/g). The catalytic activity of the nanostructured cobalt and nickel molybdates for the oxidative dehydrogenation of propane has been evaluated. The performa...