Effect of Sulfation Using Sulfate Salt Impregnation Method on Acidity of Cobalt Oxide

To enhance the acidity of cobalt oxide, sulfation was carried out using aqueous solution of cobalt sulfate impregnated on cobalt oxide and the product calcined at high temperatures. Conventional sulfation of oxides by sulfuric acid could not avoid dissolution of cobalt oxide in the sulfuric acid. The activity of cobalt oxide for acid-catalyzed ethanol dehydration reaction was greatly enhanced by sulfation using cobalt sulfate. The activity of the prepared sulfated cobalt oxide was comparable to that of conventional SiO2-Al2O3 acid catalyst. The sulfated cobalt oxide did not show activity for pentane isomerization, which was catalyzed by sulfated zirconia prepared by the same methodology of sulfate salt impregnation, using zirconium sulfate solution was impregnated onto zirconia. The highest activity was obtained by heat treatment at 1073 K. This treatment temperature is the highest among solid acid catalysts reported so far.