Studies on solid catalysts with a basic character I

Abstract

The acidic and basic properties of catalysts obtained by saturation of silica gel with various amounts of NaOH were investigated. The investigations were carried out on catalysts dried at 120 °C and roasted at 1000 °C. The strength of the superficial base was determined semiquantitatively from the adsorption of acidic indicators from nonpolar solutions. It was established that catalysts with small amounts of sodium have acidic properties and after application of larger amounts of sodium show basic properties. The superficial basicity was determined by titration with sulfuric acid in an aqueous medium and by titration with perchloric acid in anhydrous acetic acid. Attempts were also made to determine the superficial acidity of the same catalysts by titration with Na ethoxide in anhydrous picoline. The investigations showed that on the surface of the investigated catalysts, beside centers of a basic character, there exist centers of an acidic character. Moreover it was established that roasted catalysts loose their acidic character, probably as a result of splitting off of OH groups, their basicity remaining unchanged.