Differential scanning calorimetry probes acidity strength distribution in catalytic materials

Abstract

Differential scanning calorimetry (DSC) effects obtained with some catalytic solids such as amorphous silica-alumina and γ-alumina appear as an endothermic peak in the lower temperature region in a DSC thermogram, while desorption of presorbed triethylamine (TEA) from the acid sites of these solids appears as exothermic peaks in a higher temperature region. Other materials such as zeolites show a number of endothermic water-desorption peaks or a broad band covering a wide temperature range that crucially interfere with TEA-desorption peaks, and a precise evaluation of the acidity distribution in these materials is impossible. In the present work, an easy solution to this problem is found by nullifying the DSC effects caused by water desorption from the catalytic solid itself and only TEA-desorption peaks appear in the thermogram. The advantages of this DSC method over others are mentioned.