Thermal behaviour and structural variations of Mg-doped Cu-Mn mixed oxides and the catalytic activity of the thermal products in H₂O₂-decomposition

120-123Thermal decomposition of mixed copper and manganese carbonates in molar ratios 1:1 and 1:0.5 with respect to CuO: MnO2 doped with, 2.5 and 5 wt.% Mg2+ has been studied. The thermal produces obtained at different temperatures have been characterized by X-ray diffraction analysis. The catalytic activity of the thermal products has been tested in H2O2 decomposition. Calcination of mixtures at 200°C produces three crystalline phase CuO, Cu2(NO3)(OH)3 and unaffected MnCO3. The increase in temperature of treatment leads to the formation of manganese oxide which in turn reacts with CuO forming spinel CuMn2O4. The incorporated magnesium in the spinel structure occupies the octahedral coordinated sites [CuMn(CuMgMn)O4]. Catalytic activity of the undoped samples incre ses with increase in the calcination te perature up to 500°C and at 800°C it decreases. The doping wit magnesium ions shows slight change in activity for catalysts calcined at 200°C and 500°C, while conside rable increase in activity is detected for catalysts calcined at 800°C. This may be attributed to lattice inve rsion defects and distortions of the form ed spinel besides CuO present with other oxides