DTA/TGA study of copper molybdate carbothermal reduction
General and Physical Chemistry
The mechanism of copper molybdate carbothermal reduction was investigated at nonisothermal conditions by carrying out simultaneous differential thermal (DTA) and thermal-gravimetric (TGA) analyses combined with X-ray diffraction (XRD) analysis of intermediate and final products. In order to understand the influence of copper molybdate preparation method on the reduction processes, the behaviour of salts prepared by (i) calcination of oxides mixture and (ii) co-precipitation from water soluble salts of Cu and Mo were studied at linear heating. It was revealed that the obtained copper molybdates differ by modification and particle size distribution. Nevertheless, the reduction process of the both copper molybdates involves low-exothermic carbothermal reactions and is accompanied by sequential formation of partially reduced active phase Cu5Mo6O18, as well as Cu2O, MoO2, Cu and Mo. Chemical reactions possibly occurring during the heating of CuMoO4-C system on the basis of DTA/TG curves and XRD analyses results of quenched reaction products have been proposed.