Microwave-Driven Reduction Accelerates Oxygen Exchange in Perovskite Oxides.

Microwave-assisted oxide reduction has emerged as a promising method to electrify chemical looping processes for renewable hydrogen production. Moreover, these thermochemical cycles can be used for thermochemical air separation, electrifying the O generation by applying microwaves in the reduction step. This approach offers an alternative to conventional cryogenic air separation, producing pure streams of O and N. The electrification by microwaves lowers the requirements for titanate perovskites (CaTiMnO), which typically demand high temperatures for thermochemical cycles. Microwave activation allows for a drastic reduction in the operation conditions of the reduction reaction, leading to unprecedentedly rapid absorption-desorption cycles (<3 min per cycle). For CaTiMnO, we achieved a cycle-averaged O production of 2.6 mL g min at 800 °C, surpassing conventional values of materials operating in the high-temperature regime. This method could significantly impact thermochemical air separation by enabling a faster oxygen absorption-desorption cycle at more moderate temperatures than those of conventionally heated processes.