Nanocrystalline Mixed Oxides Containing Magnesium Prepared by a Combined Sol-Gel and Self-Combustion Method for Catalyst Applications

Abstract

MgFe 2 O 4 spinel ferrite and La 0.6 Pb 0.2 Mg 0.2 MnO 3 perovskite nanopowders were synthesized by a combined sol-gel and self-combustion method and heat treatment. The morphological and structural characterization of the obtained powders has been performed with various techniques: X-ray diffraction (XRD), SEM observations, EDAX spectroscopy and BET analysis. The samples have been catalytically tested in flameless combustion reaction of acetone, benzene, pro pane and Pb free gasoline at atmospheric pressure. The results revealed a higher catalytic activity of La 0.6 Pb 0.2 Mg 0.2 MnO 3 perovskite than that of MgFe 2 O 4 ferrite. This higher catalytic activity can be ascribed to smaller crystallite size (27 nm), larger surface area (8.5 m 2 /g) and the presence of manganese cations with variable valence (Mn 3+ - Mn 4+ ). The current results suggest that La 0.6 Pb 0.2 Mg 0.2 MnO 3 perovskite is preferable to the Mg ferrite and that it can be a promising catalyst for acetone and propane combustion at low temperatures.