Oxygen uncoupling behaviour for ilmenite ore oxygen carrier generated from a calcination treatment mixed with natural manganese ore.

Chemical looping with O2 uncoupling aims at using an oxygen carrier (OC) with O2 uncoupling behaviour to promote fuel conversion. Natural ilmenite ores have been considered highly promising OCs for chemical looping technology; however, they do not possess any O2 uncoupling behaviour. Mn‐modified ilmenite ores as OCs are capable of O2 uncoupling, while most of them are synthesized via complicated procedures by using costly chemicals. In this study, a strategy of calcination treatment on ilmenite ores mixed with manganese ores has been established to introduce Mn into the ilmenite OCs, endowing them with O2 uncoupling behaviour in a simple and low‐cost manner. The O2 uncoupling behaviour from Mn‐modified ilmenite ores is mainly due to the newly formed (Fe1−xMnx)2O3/(Fe1−xMnx)3O4 crystal phases generated during the calcination treatment, which also alleviate the thermodynamic limit of the Mn2O3‐Mn3O4 redox pair. As a result, the Mn‐modified ilmenite ore OCs can release O2 at high temperatures when decreasing the oxygen partial pressure. But more importantly, the reduced OCs can be restored in the air isothermally. This established simple calcination treatment method can be used as a low‐cost strategy for producing ilmenite‐based OCs with O2 uncoupling behaviour. The O2 uncoupling behaviour is expected to be beneficial to chemical looping combustion of fuels, promote fuel conversion, minimize OC loading, and reduce energy consumption. [ABSTRACT FROM AUTHOR]