Characterization of silica dispersed lanthana by CO2 adsorption

CO 2 adsorption on a series of La 2 O 3 /SiO 2 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, also supported by data obtained from other physical characterization techniques (XRD, TEM, XPS). Such a model assumes that patches of an amorphous 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 2 O 3 . The nature of the mixed phase imposes a top limit of 2.8 molecules nm −2 to its CO 2 adsorption capacity.