Phase transition of Fe2O3-NiO to NiFe2O4 in perovskite catalytic particles for enhanced methane chemical looping reforming-decomposition with CO2 conversion

•Perovskite particle of Fe2O3-NiO/La0.8Sr0.2FeO3 is proposed as an oxygen carrier.•Transition of mixed Fe2O3-NiO oxides to single NiFe2O4 enhances syngas yields.•Reinforced carrier activity and stability over repeated cycles are firstly reported.•Enabling a looping process of CH4 reforming-decomposition with CO2 conversion.

This work introduced a perovskite catalytic particle of Fe2O3-NiO/La0.8Sr0.2FeO3 as an oxygen carrier and investigated its long-term activity and stability in a novel methane Chemical Looping Reforming-Decomposition (CLRD) process. Carbon dioxide (CO2) was injected for the oxidation of the reduced catalytic particle and its carbon deposit, resulting in the accelerated production of syngas. The catalytic particle showed over 97% of CH4 conversion over 60 min and the reduced catalytic particle was partially re-oxidized by both O2 and CO2 with the conversion of CO2 into CO maintaining about 93% over 80 min. The separate phases of Fe2O3/NiO were gradually merged to the single crystal phase of NiFe2O4 during the calcination of the two metal oxides and the continuous redox reaction cycle. The increased crystallinity can lead to the improvement of both activity and stability due to the enhanced oxygen-carrying capacity. The structure of the catalytic particle was well preserved and its activity has been stable in the long-term CLRD cycle with the combination of CO2 utilization.

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