Scandium substituted nickel–cobalt ferrite nanoparticles for catalyst applications

Abstract

Nanograined Ni0.5Co0.5ScxFe2−xO4 (x=0, 0.05, 0.1 and 0.2) spinel ferrites were prepared by sol–gel self-combustion method and heat treatment at 900°C for 4h. Their structure and surface properties were investigated by X-ray diffraction, scanning electron microscopy, EDX spectroscopy and BET analysis. The catalyst properties of the ferrite nanopowders were tested in the catalytic combustion of acetone, propane and benzene. The results revealed that the partial substitution of Fe3+ by Sc3+ ions on the octahedral sites of spinel structure of Ni0.5Co0.5Fe2O4 ferrite has a favorable effect on the catalytic activity of this ferrite. The Ni0.5Co0.5Sc0.2Fe1.8O4 ferrite composition was found to be the most active catalyst and can be a good candidate for catalytic combustion of propane and acetone at moderate temperatures. The acetone conversion over this catalyst exceeds 90% at 400°C. The enhancement of the catalytic activity of the Sc doped Ni–Co ferrites may be ascribed to smaller crystallite sizes (35–39nm), larger specific surface areas (29–32m2/g) and the presence of Sc cations in spinel structure.