Montmorillonite‐Supported Iron Oxide for Hydrogen Storage by Chemical Looping

Abstract

AbstractA technology for hydrogen storage is proposed based on the repeated reduction of magnetite (Fe3O4+4 H2→3 Fe+4 H2O) and the oxidization of metallic iron (3 Fe+4 H2O→Fe3O4+4 H2). Herein, we prepared three montmorillonite (MMT)‐supported iron oxide samples by using a sol–gel method and demonstrated their application in hydrogen storage through a chemical looping process. The redox performance of the Fe‐MMT samples was studied at 600 °C in a fixed‐bed reactor. The results showed that 70 Fe‐MMT (with 70 wt % Fe2O3) exhibited relatively good redox performance owing to its excellent anti‐agglomeration ability and sintering resistance. After the redox performance tests, Fe2SiO4 was observed in all Fe‐MMT samples. It was worth noting that the diffraction intensity of Fe2SiO4 in 70 Fe‐MMT was much weaker than in 30 Fe‐MMT (30 wt % Fe2O3) and 50 Fe‐MMT (50 wt % Fe2O3), which was owed to the high MMT content in the 30 Fe‐MMT and 50 Fe‐MMT samples. The formation of Fe2SiO4 in repeated redox cycles could reduce the stability and recyclability of Fe‐MMT samples. This might be the major reason for the better hydrogen storage performance of 70 Fe‐MMT compared with 30 Fe‐MMT and 50 Fe‐MMT.