Characterization of mixed amorphous/crystalline cerium oxide supported on SiO2

摘要: Abstract Various analyses techniques were employed for characterization of mixed amorphous/crystalline CeO2 supported on SiO2 catalysts prepared by incipient wetness using (i) Ce4+-ammonium nitrate (CeqN) aqueous solution, and grafting (ii) Ce4+-methoxyethoxide (CeqA) alcoholic solution. X-ray diffraction (XRD), temperature programmed reduction (TPR), transmission electron microscopy-energy dispersive analysis (TEM-EDX) used to obtain information about the dispersion crystallinity SiO2. After calcination at 500°C, XRD indicated formation larger crystallites CeqN compared CeqA catalysts. Catalysts 800°C led a higher degree particles with calcined 500°C. TEM revealed that ceria is present mostly as an amorphous phase, whereas crystalline CeO2. The particle size calculated from data, TPR profile, XPS ICe3d/ISi2p intensity ratio, better support than EPR data showed presence paramagnetic Ce3+ defects in structure only cerium surface Ce4+. observed differences between presented correlation activity obtained ethylbenzene oxidative dehydrogenation CO oxidation.