Dry Reforming of Methane Mediated through In Situ Generated Molecular Level Nanocomposite Derived from Thermally Regenerable High-Entropy Spinel Oxide

The study focuses on synthesizing a series of high-entropy spinel oxides (HESOs) and their potential role in the dry reforming of methane (DRM). A phase pure (Mn0.2Fe0.2Co0.2Ni0.2Cu0.2)Al2O4 HESO has demonstrated high catalytic activity, converting 97% CH4 and 99% CO2 during 100 h DRM with H2/CO ∼ 1. Through characterization of the as-prepared and aged catalyst samples, we have shown that the initial spinel phase breaks down into constituent metal oxides in the reaction medium and then regenerates itself from the degraded phases by annealing nearly at the synthesis temperature. This is an intriguing observation, since the structural transformation does not alter the DRM activity. This result defines the unusual reversible thermal switching that takes place between the pristine HESO phase and the decomposed phases. It also highlights the need for further investigation into the role of the decomposed phases that are produced during DRM. To address this issue, we have investigated the structure–property relationship within the context of an in situ generated molecular level nanocomposite.