Abstract
The current study investigates Ce-modified SrFeO3-delta oxygen carriers for oxidative dehydrogenation (ODH) of ethane coupled with CO2 splitting in a chemical looping manner. During 39 cycles of redox testing over the sample of 0.2Ce/SrFeO3, up to 29% ethane conversion and 82% ethylene selectivity are achieved, and the CO generation in the subsequent CO2 splitting step is 0.25 mmol/g. XPS characterization results indicate decreased Fe2+/(Fe3++Fe4+) ratio as well as increased active oxygen species proportion on the near-surface of Ce-modified samples, which are responsible for the improved activity of the 0.2Ce/SrFeO3 in ethane ODH reaction. DFT calculations further reveal that the increased ODH activity of 0.2Ce/SrFeO3 is due to the lower surface oxygen vacancy formation energy upon Ce promotion. Moreover, the higher resistance of lattice oxygen diffusion from the bulk to the surface is the main reason for the superior ethylene selectivity attained by the CO2-regenerated sample than that by O-2 regeneration.
NSTL
Elsevier