A Relation between Oxidation State of Sulfur and Acidic Property of Iron Oxide Containing Sulfur

Abstract Five kinds of iron oxide catalysts promoted with sulfur were prepared by impregnating Fe(OH)3 with (NH4)2SO4 and by treating Fe2O3 and Fe(OH)3 with H2S and SO2. Changes in acidic properties of the catalysts with changes in oxidation states of sulfur were investigated by test reactions such as isomerization of cyclopropane and dehydration of 2-propanol over the oxidized or reduced catalysts. It has been found that the generation of acidic properties of the catalysts was independent of the kinds of the starting sulfur compounds, but dependent on the oxidation states of the sulfur. The sulfur in the highest oxidation state was responsible for the strongly acidic property of the catalyst.