A High Pressure <i>Operando</i> Spectroscopy Examination of Bimetal Interactions in ‘Metal Efficient’ Palladium/In₂O₃/Al₂O₃ Catalysts for CO₂ Hydrogenation

Abstract

CO₂ hydrogenation to methanol has the potential to serve as a sustainable route to a wide variety of hydrocarbons, fuels and plastics in the quest for net zero. Synergistic Pd/In₂ O₃ (Palldium on Indium Oxide) catalysts show high CO₂ conversion and methanol selectivity, enhancing methanol yield. The identity of the optimal active site for this reaction is unclear, either as a Pd-In alloy, proximate metals, or distinct sites. In this work, we demonstrate that metal-efficient Pd/In₂ O₃ species dispersed on Al₂ O₃ can match the performance of pure Pd/In₂ O₃ systems. Further, we follow the evolution of both Pd and In sites, and surface species, under operando reaction conditions using X-ray Absorption Spectroscpy (XAS) and infrared (IR) spectroscopy. In doing so, we can determine both the nature of the active sites and the influence on the catalytic mechanism.