Enhancing performance of chemical looping reforming-decomposition of CH4 with $CO_2$ conversion by phase merge of $Fe_2O_3-NiO$ in perovskite oxide carriers

Abstract

This work introduced a perovskite catalyst of $Fe_2O_3-NiO/La_{0.8}Sr_{0.2}FeO_3$ as an oxygen carrier and investigated its long-term activity and stability in a novel methane Chemical Looping Reforming-Decomposition (CLRD) process. Carbon dioxide ($CO_2$) was injected for the oxidation of the reduced catalyst and its carbon deposit, resulting in the accelerated production of syngas. The catalyst showed over 97% of $CH_4$ conversion over 60 minutes and the reduced catalyst was partially re-oxidized by both $O_2$ and $CO_2$ with the conversion of $CO_2$ into CO maintaining about 93% over 80 minutes. The separate phases of $Fe_2$O_3/NiO$ were gradually merged to the single crystal phase of $NiFe_2O_4$ 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 catalyst was well preserved and its activity has been stable in the long-term CLRD cycle with the combination of $CO_2$ utilization.