Study of correlation between activity and structural properties of Cu-(Cr, Mn and Co)2 nano mixed oxides in VOC combustion

The correlation between structure and catalytic activities of Cu-(Cr, Mn and Co)(2) mixed oxides synthesized by a sol gel combustion method was investigated for the oxidation of 2-propanol. The catalysts were characterized by FUR, XRD, XPS, TPR and UV-vis DRS. Although the same preparation conditions were used for all the systems, obtained samples presented different pureness degrees. The structural characterization by XRD revealed that copper-chromite was pure CuCr2O4, while copper-manganese and copper-cobalt mixed oxides resulted in a mixture of the spine' (CuMn2O4 and Cu0.15Co2.85O4, respectively) and copper oxide phases. UV-vis DRS results also indicated a larger presence of small crystallites of CuO in the copper-cobalt oxide. Copper-cobalt oxide exhibited the highest activity in 2-propanol combustion which is explained, as expected for a Mars van Krevelen mechanism, by its higher reducibility at the reaction conditions and by a possible synergistic effect between this mixed oxide and CuO particles. (C) 2013 Elsevier Ltd and Techna Group S.r.l. All rights reserved.