engleski

Thermal evolution of gels prepared by modification of aluminum sec-butoxide with ethyl acetoacetate intended for use as ceria catalyst carriers

A recent investigation of doped ceria catalyst, as well as advanced synthesis methods of ceria catalyst support will be presented. First, a brief review of the contribution in the field of nanocrystalline ceria synthesis will be given, in which the synthesis and properties of ceria doped with different transition metal ions will be addressed, with a particular focus on copper and manganese doped ceria. Afterwards, the sol-gel synthesis of gels prepared by chelation of aluminum sec-butoxide (Asb) with ethyl acetoacetate (Eaa) in various amounts will be described. Finally, special attention will be payed to thermal evolution study of the obtained gels and assessment of their suitability as ceria catalyst support. Samples were characterized by scanning electron microscopy (SEM), low angle laser light scattering (LALLS), differential thermal and thermo-gravimetric analysis (DTA/TGA), Fourier-transformed infra-red spectroscopy (FTIR) and X-ray diffraction (XRD). It was established that samples with a low Eaa/Asb ratio are mainly amorphous, whilst the samples with a greater Eaa/Asb ratio are predominantly chelate. The crystallization of γ- Al2O3 takes place between 600 and 1000 °C in two separate processes for all investigated samples. On the other hand, a complete transition to α- Al2O3 at 1200 °C occurs exclusively in samples with a high Eaa/Asb ratio, while it is only partial for samples with a low Eaa/Asb ratio. The observed mass loss is in concordance with the hypothesis that the overall gel content in the samples could be represented by a simplified formula Al(Eaa)xO(3-x)/2, where x is the Eaa/Asb ratio. In addition to thermal evolution, the gel- chelate duality of the samples is reflected in the morphology and particle size distribution. Proper synthesis parameters, as well as thermal treatment conditions enable the tailoring of alumina properties for ceria catalyst support.

alumina ; ceria ; sol-gel ; chelation ; thermal evolution

nije evidentirano