Microwave-Driven Reduction Accelerates Oxygen Exchange in Perovskite Oxides

Abstract

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 2 generation by applying microwaves in the reduction step. This approach offers an alternative to conventional cryogenic air separation, producing pure streams of O 2 and N 2 . The electrification by microwaves lowers the requirements for titanate perovskites (CaTi 1−x Mn x O 3−δ ), 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 CaTi 0.8 Mn 0.2 O 3−δ , we achieved a cycle-averaged O 2 production of 2.6 mL g −1 min −1 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.