Calcium and magnesium stannates in catalytic conversion of isopropanol under supercritical conditions

Conversion of isopropanol under supercritical conditions (400 °C, 11.0 MPa) on calcium and magnesium stannates MSnO3 (M = Ca, Mg) was studied. The main direction of the process is dehydrogenation of isopropanol to acetone, which then enters into the aldol condensation with selective formation of isomeric mesityl oxides. Products of hydrogenation of the C=C and C=0 bonds in mesityl oxide as well as products of isopropanol dehydration were also obtained. Under the experimental conditions, isopropanol is both a supercritical solvent and a source of hydrogen for hydrogenation of the multiple bonds. According to the results of diffuse reflectance infrared Fourier transform spectroscopy study using deuterated chloroform as a probe molecule, basic oxygen sites of the catalysts are of medium strength. During the conversion of isopropanol the more active catalyst MgSnO3 completely decomposes into the oxides MgO and SnO2 and the latter is then reduced to metallic tin, while the less active catalyst CaSnO3 is reduced slightly.