Thermogravimetric insight in the reduction of xCuO – (1-x)MoO<inf>3</inf> oxide system (0.1 ≤ x ≤ 0.9) by hydrogen

Abstract

The oxide mixtures xCuO-(1-x) MoO3 were synthesized by gel-combustion procedure. The existence of phase mixture CuO + Cu3Mo2O9 and MoO3 + CuMoO4 in CuO-rich and MoO3 -rich composition region, respectively, were evidenced. The constant heating rate thermogravimetry in hydrogen atmosphere revealed that the reduction reactions proceed within the two clearly separated temperature regions. On the basis of mass changes, the mechanism of reduction processes was discussed. The measurements revealed considerable inhibition of CuO reduction by MoO3, and huge acceleration of MoO3 → MoO2 reduction step by copper. The particularities found in this system were commented in relation to our similar studies in NiO-MoO3 and CuO-WO3 systems. For particular composition, x = 0.5, existing preferably in form of a-CuMoO4, kinetic parameters of reduction were determined. The composition of oxide mixture influenced the particle size and morphology of resulting metallic Cu-Mo composites.