Materials for solid base catalysts and oxygen storage

Abstract

This thesis investigates oxides as solid base catalysts and as oxygen storage materials. Supported cesium and lanthanum oxides on SBA-15 were prepared using wet impregnation method and tested for the epoxidation of olefins using H2O2 as oxidant. With 10 wt% loading of cesium on SBA-15, 97% conversion of cyclohexene can be achieved after 5 h with a high selectivity of 90% to cyclohexene oxide. Another base catalyst, KF supported on alumina, was investigated for the synthesis of pseudoionone by the aldol condensation of citral and acetone. Studies of the loading of KF on alumina showed that a loading of 8.5 mmol KF/g was better with an excellent citral conversion 99% with 97% selectivity to pseudoionone. In the study on oxygen storage materials, nanocrystalline cerium-zirconium mixed oxides were prepared by the hydrothermal treatment of the hydroxides at 100 ?C. Hydrothermally treated samples were more reducible as oxygen could be removed at lower temperature than for the untreated ceria-zirconia. Despite calcination at 1000 ?C, the surface area of the hydrothermally synthesized samples remained relatively high at ~11?12 m2/g while the untreated Ce0.5Zr0.5O2 had only 4.2 m2/g. The addition of silica and iron to ceria-zirconia further increased the surface area and the oxygen storage capacity.