Thermal characterization and catalytic properties of ZnO-Co3O4/Al2O3 system

The effect of zinc oxide on thermal and physicochemical properties Of Co3O4 /Al2O3 system has been investigated. Different ratios of zinc nitrate solut ions were added to mixed ratios of cobalt carbonate and aluminum hydroxide. The thermal decomposition of selected samples was studied by means of ther mal analysis (TG & DTG) technique. The pure and doped solids were subjected to thermal treatment at (300-1000 degreesC). The thermal products of all s amples were characterized using XRD analysis and IR spectroscopy. The decom position of hydrogen peroxide was used to measure the catalytic activity of ZnO-Co3O4/Al2O3 system at 30, 40 and 50 degreesC. The results showed that, the thermal treatment of zinc nitrate yielded ZnO at about 255 degreesC. C obalt carbonate decomposed to Co3O4 and CoO at about 250 and 880 degreesC. The compounds CoAl2O4 and ZnAl2O4 were formed as a result of solid-solid in teraction and they might form a solid solution between them of the formula (Co1-xZnxAl2O4). Both of pure ZnO and Al2O3 were inactive in H2O2 decomposi tion. Pure Co3O4 showed high catalytic activity. The mixed oxides of Co3O4/ Al2O3 system led to enhancement of its catalytic activity. Further increase in the amount of ZnO, led to sharp decrease in the catalytic activity of t he system.