Exploring the stability of Fe2O3-MgAl2O4 oxygen storage materials for CO production from CO2

The stability of Fe2O3-MgAl2O4 oxygen storage materials (OSMs) was investigated over 1000 redox cycles using H-2 as reductant and CO2 as oxidant. Three different materials, with a nominal Fe2O3 amount of 10 wt%, 30 wt% and 50 wt%, were evaluated. Characterization techniques such as N-2 adsorption, XRD and STEM-EDX were applied to study the evolution of morphological and crystallographic properties. XRD results show that Fe is incorporated in the MgAl2O4 lattice of the as prepared materials, yielding a Mg-Fe-Al-O spinel structure. After redox cycling, part of Fe still remains within the spinel. The results of redox cycling reveal superior properties for 10Fe(2)O(3)-MgAl2O4, exhibiting stability in terms of morphology and, with an average space-time yield of 700 mmol(CO) s(-1) kg(Fe)(-1), the highest activity among the OSMs studied. However, 50Fe(2)O(3)-MgAl2O4 performs best in terms of overall CO yield, i e. 0.6 mol CO kg(OSM)(-1), more than twofold higher compared to 10Fe(2)O(3)-MgAl2O4 and 30Fe(2)O(3)-MgAl2O4 even after 1000 cycles. Deactivation through sintering occurs in all three materials, though to a lesser extent for 10Fe(2)O(3)-MgAl2O4. Phase transformation to a MgxFe1-xO phase predominantly causes a loss of oxygen storage capacity in 30Fe(2)O(3)-MgAl2O4 and 50Fe(2)O(3)-MgAl2O4.