Oxidative dehydrogenation of ethane and subsequent CO2 activation on Ce-incorporated FeTiOx metal oxides

The Ce-incorporated FeTiOx catalysts were investigated for an oxidative dehydrogenation (ODH) of C2H6 (reduction step) and successive CO2 activation to CO (oxidation step) through redox chemical looping (CL-ODH) cycles of those partially reducible metal oxides via mutual phase changes between Fe2+/Fe3+ and Ti3+/Ti4+ species. A higher lattice oxygen mobility with less surface electrophilic oxygen natures on an optimal FeCeTiOx(1) (Fe/Ce molar ratio = 1.0) was responsible for an enhanced cyclic stability. The lattice expansion by Ce-incorporation into the Fe/TiO2 structures not only enhanced charge transport rates but also generated thermally stable trigonal ilmenite FeTiO3 phases. These larger oxygen storage capacity of CeO2 on the FeCeTiOx(1) also revealed an excellent 5-times cyclic stability with a stable C2H4 formation rate and C2H4 selectivity of 84.1% for a reduction step of ethane as well as an excellent CO2 activation to CO at 600 °C for an oxidation step (named as CL-ODH). Those superior catalytic performances on the FeCeTiOx(1) were attributed to the partial formation of FeTiO3 phases, which caused an improved lattice oxygen mobility by CeO2 contribution with its higher oxygen storage nature and facile redox property. The large amount of non-stoichiometric surface oxygens at a higher Fe/Ce ratio above 2 mainly caused an enhanced CO2 byproduct formation by the full oxidation of C2H6. The synergy effects on the FeCeTiOx(1) were attributed to facile redox properties of lattice oxygen vacant sites by partially forming the strongly interacted stable FeTiO3 phases with its resistance to coke depositions.