Decomposition of isopropanol on magnesium oxide/silica in relation to texture, acidity and chemical composition

Abstract

Two series of MgO/SiO 2 catalysts were prepared either by mechanical mixing (MM) or by co-precipitation (COP) in the composition range 16–83 mol-%. Catalysts calcined at 500, 600 and 800°C were characterised by nitrogen adsorption, chemisorption of pyridine at 150°C, and catalytic conversion of 2-propanol at 260°C. Dehydration (DHD) and dehydrogenation (DHG) were independent of available S BET, although DHG was much favoured by low-area catalysts. DHD to propene dropped by pre-treatment at 800°C due to the formation of enstatite and to the decrease in surface hydroxyls involved in catalysis. DHD and total conversion of alcohol increased linearly as a function of surface acidity per unit area, whereas DHG exhibited a reverse behaviour. In general, COP catalysts catalyze decomposition to a higher degree in comparison to the corresponding MM catalysts.