CHARACTERIZATION OF SILICA DISPERSED LANTHANA BY CO2 ADSORPTION

CO2 adsorption on a series of La2O3/SiO2 samples, with lanthana weight loadings ranging from 1.6% to 75%, have been studied. The results are interpreted on the grounds of a lantana-silica interaction model, als o supported by data obtained from other physical characterization tech niques (XRD, TEM, XPS). Such a model assumes that patches of an amorph ous La-Si-O phase, embedded into the silica matrix, modify the support surface in a progressive way, leading to a full coverage for 37.5% La 2O3. The nature of the mixed phase imposes a top limit of 2.8 molecule s nm-2 to its CO2 adsorption capacity.