Promoting CO2 hydrogenation to light olefins over high-entropy oxide-supported Fe-based catalysts by tuning the strong metal–support interaction

Abstract

High-entropy oxides (HEOs) have recently emerged as a novel class of catalyst supports with highly tunable composition–function relationships, showing significant potential across various chemical reactions. Herein, we developed highly dispersed iron oxide nanoparticles supported on HEOs through a one-step precipitation method, utilizing a spinel FeAl₂O₄ framework doped with multiple elements. The resulting HEOs demonstrated markedly stronger metal–support interactions (SMSI) compared to pure FeAl₂O₄. Structural analysis via XRD, HTEM, and EDS confirmed the formation of a single-phase HEO matrix with smaller Fe₂O₃ nanoparticles on the surface relative to FeAl₂O₄. H₂-TPR analysis revealed a lower reduction temperature for HEOs than FeAl₂O₄, indicating enhanced reducibility. With catalytic CO₂ hydrogenation as a model, the selection of HEOs effectively enhances the SMSI effect, thereby significantly promoting the generation of olefins and resulting in superior catalytic performance. Specifically, the FeNa/HEO catalyst exhibited a remarkable CO₂ conversion rate of 40.03%, while its selectivity for C₂–C₄ olefins (C⁼₂–C⁼₄) showed a substantial increase from 14.21% for FeNa/FeAl₂O₄ to 39.28%. Furthermore, H₂-TPD analysis showed that FeNa/HEO exhibited improved H₂ adsorption capability and resistance to secondary hydrogenation, thereby increasing the olefin/paraffin (O/P) ratio and enhancing C⁼₂–C⁼₄ selectivity. This study presents a promising approach for designing high-entropy-supported catalysts and offers valuable insights for developing metal oxide-supported catalysts with tailored SMSI effects.