Microwave-Driven\nReduction Accelerates Oxygen Exchange\nin Perovskite Oxides

Microwave-assisted oxide reduction has emerged as a promising\nmethod\nto electrify chemical looping processes for renewable hydrogen production.\nMoreover, these thermochemical cycles can be used for thermochemical\nair separation, electrifying the O<sub>2</sub> generation by applying\nmicrowaves in the reduction step. This approach offers an alternative\nto conventional cryogenic air separation, producing pure streams of\nO<sub>2</sub> and N<sub>2</sub>. The electrification by microwaves\nlowers the requirements for titanate perovskites (CaTi<sub>1–<i>x</i></sub>Mn<sub><i>x</i></sub>O<sub>3−δ</sub>), which typically demand high temperatures for thermochemical cycles.\nMicrowave activation allows for a drastic reduction in the operation\nconditions of the reduction reaction, leading to unprecedentedly rapid\nabsorption–desorption cycles (<3 min per cycle). For CaTi<sub>0.8</sub>Mn<sub>0.2</sub>O<sub>3−δ</sub>, we achieved\na cycle-averaged O<sub>2</sub> production of 2.6 mL g<sup>–1</sup> min<sup>–1</sup> at 800 °C, surpassing conventional\nvalues of materials operating in the high-temperature regime. This\nmethod could significantly impact thermochemical air separation by\nenabling a faster oxygen absorption–desorption cycle at more\nmoderate temperatures than those of conventionally heated processes.