TG AND DTA INVESTIGATION OF ZRO2-SO42- CATALYSTS EXPOSED TO HEXANE, METHYLCYCLOPENTANE AND CYCLOHEXANE

ZrO2-SO42- catalysts with different sulfur contents were analysed with thermal methods coupled with mass spectrometry after exposure to mixt ures of hexane, methylcyclopentane, and cyclohexane in argon. The reac tion of the hydrocarbons led to carbonaceous deposits, but an importan t part of hydrocarbon remained chemisorbed as well. Heating these samp les in He atmosphere provoked the decomposition of these deposits with evolution of CO2 and CO, and also of SO2 and SO. At the same time, CO S was evidenced in the reaction products. The release of these molecul es occurred below the activation temperature of the catalysts. The beh avior of the catalysts depended both on reactant molecule and sulfur c ontent. The analyses clearly evidenced the oxidation ability of ZrO2-S O42- catalysts.