Mechanochemically assisted solid state synthesis, characterization, and catalytic properties of MgWO4

The synthesis of MgWO4 nanopowders was achieved by mechanically activated and following thermal treatment at 850 A degrees C of two mixtures, containing the pure oxides (MgO/WO3) and magnesium carbonate trihydrate and tungsten oxide (MgCO3 center dot 3H(2)O/WO3) as precursors. The obtained samples have been analyzed by the X-ray powder diffraction, infrared spectroscopy (IR), thermal analysis, specific surface area, transmission electron microscopy (TEM, SAED, and XEDS), and X-ray photoelectron spectroscopy. The prepared samples were modified with 0.5 wt% Pd, and the catalytic activities have been measured in reaction of complete oxidation of CO, methane, n-hexane, and toluene. It has been observed that Pd-containing samples with 3 wt% WO3 are more active than the MgWO4/Pd, the most remarkable improvement being achieved in the reaction of toluene combustion. This result is explained by the presence of the palladium in Pd4+ state (as PdO2 particles) due to the stabilization role of the WO3-matrix.