Co3O4/CeO2 and CeO2-ZrO2 composite catalysts for methane combustion: correlation between morphology reduction properties and catalytic activity

Co3O4/CeO2and Co3O4/CeO2-ZrO2 composite catalysts have been prepared by two different techniques, co-precipitation by citrate method and impregnation with cobalt nitrate of pre-formed ceria and ceria-zirconia oxides. The materials, as prepared and after ageing at 750 C 7 h, were tested for methane combustion and the catalytic performances were compared with those of a commercial Co3O4, used as reference. A significant improvement of the activity was observed in the composite oxide Co3O4 (30 wt%)/CeO2(70 wt%), prepared by citrate method, which exhibits the lowest light-off temperature of methane (T50= 400 C) and does not suffer deactivation after calcination at 750 C 7 h