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

Abstract

• Oxidative dehydrogenation (ODH) with successive CO 2 activation was studied. • Number of lattice oxygen mobility was related with chemical looping (CL)-ODH activity. • Facile redox property of CeFeTiO x was enhanced with new FeTiO 3 phases formation. The Ce-incorporated FeTiO x catalysts were investigated for an oxidative dehydrogenation (ODH) of C 2 H 6 (reduction step) and successive CO 2 activation to CO (oxidation step) through redox chemical looping (CL-ODH) cycles of those partially reducible metal oxides via mutual phase changes between Fe 2+ /Fe 3+ and Ti 3+ /Ti 4+ species. A higher lattice oxygen mobility with less surface electrophilic oxygen natures on an optimal FeCeTiO x (1) (Fe/Ce molar ratio = 1.0) was responsible for an enhanced cyclic stability. The lattice expansion by Ce-incorporation into the Fe/TiO 2 structures not only enhanced charge transport rates but also generated thermally stable trigonal ilmenite FeTiO 3 phases. These larger oxygen storage capacity of CeO 2 on the FeCeTiO x (1) also revealed an excellent 5-times cyclic stability with a stable C 2 H 4 formation rate and C 2 H 4 selectivity of 84.1% for a reduction step of ethane as well as an excellent CO 2 activation to CO at 600 °C for an oxidation step (named as CL-ODH). Those superior catalytic performances on the FeCeTiO x (1) were attributed to the partial formation of FeTiO 3 phases, which caused an improved lattice oxygen mobility by CeO 2 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 CO 2 byproduct formation by the full oxidation of C 2 H 6 . The synergy effects on the FeCeTiO x (1) were attributed to facile redox properties of lattice oxygen vacant sites by partially forming the strongly interacted stable FeTiO 3 phases with its resistance to coke depositions.