Tailoring an Fe–O<sub>v</sub>–Ce–Triggered Phase‐Reversible Oxygen Carrier for Intensified Chemical Looping CO<sub>2</sub> Splitting
Zhao Sun, Zhao Sun, Kun Lei, Louise R. Smith, Nicholas F. Dummer, Richard J. Lewis, Haifeng Qi, Kieran J. Aggett, Stuart H. Taylor, Zhiqiang Sun, Zhiqiang Sun, Graham J. Hutchings
Abstract
ABSTRACT Advanced oxygen carrier plays a pivotal role in various chemical looping processes, such as CO 2 splitting. However, oxygen carriers have been restricted by deactivation and inferior oxygen transferability at low temperatures. Herein, we design an Fe–O v –Ce–triggered phase‐reversible CeO 2− x ·Fe·CaO ↔ CeO 2 ·Ca 2 Fe 2 O 5 oxygen carrier with strong electron‐donating ability, which activates CO 2 at low temperatures and promotes oxygen transformation. Results reveal that the maximum CO 2 conversion and CO yield obtained with 50 mol% CeO 2− x ·Fe·CaO are, respectively, 426% and 53.6 times higher than those of Fe·CaO at 700°C. This unique multiphase material also retains exceptional redox durability, with no obvious deactivation after 100 splitting cycles. The addition of Ce promotes the formation of the Fe–O v –Ce structure, which acts as an activator, triggers CO 2 splitting, and lowers the energy barrier of C═O dissociation. The metallic Fe plays a role in consuming O 2− lattice transformed from Fe–O v –Ce, whereas CaO acts as a structure promoter that enables phase‐reversible Fe 0 ↔ Fe 3+ looping.