New evidences in CO oxidation and selective chemisorption of carbon oxides on different alkaline ferrite crystal phases (NaFeO2 and LiFeO2)

Different thermogravimetric and CO oxidation analyses were performed on sodium and lithium ferrites (NaFeO2 and LiFeO2) to study CO-CO2 sorption selectivity and mechanism, in presence and absence of oxygen. In both phases, CO is chemisorbed producing the corresponding alkaline carbonate and secondary iron phases with reduced oxidation states. In all the cases, NaFeO2 showed better sorption and oxidation properties than the Libased ferrite. The sorption and catalytic behavior observed between the alkaline ferrites studied are associated to the crystal structures and alkali composition. Although Li and Na chemical affinity to these gases is similar, their availability changes based on the ferrite crystal structure. Additionally, on CO oxidation properties, the ferrite with tetrahedrally coordinated Fe3+ ions presented better efficiency against CO oxidation than the ferrite with octahedrally coordinated Fe3+ ions.