Development of In₂O₃-based Catalysts for CO₂-based Methanol Production.

Abstract

CO₂ valorization into chemicals and fuels is a key area in current academic and industrial research, with thermocatalytic hydrogenation to methanol comprising one of the most advanced routes. Life-cycle analysis coupled to the framework of planetary boundaries has recently confirmed the sustainability of this process in absolute terms, emphasizing the need for cheaper CO₂ and renewable H₂ and for a catalytic system embracing high activity, selectivity, and durability to meet economic requirements. Herein, our research efforts aimed to gather atomic-level understanding of electronic and geometric properties of active sites in breakthrough In₂O₃-based catalytic systems guiding their development are reviewed. In-depth mechanistic elucidations identified limited hydrogen activation ability as well as water-driven sintering as limitations of pure In₂O₃. The former aspect was successfully addressed by adding through coprecipitation a minimal amount of palladium, forming tiny clusters strongly anchored to the oxide lattice leading to an unprecedented sustained methanol productivity. The use of monoclinic zirconia as a carrier, enabling high In₂O₃ dispersion in two-dimensional nanostructures, inducing the formation of additional active sites on In₂O₃, and contributing to CO₂ activation, offered an efficient way to further boost activity and tackle In₂O₃ sintering. Overall, our findings set solid grounds to rationally design a supported and promoted In₂O₃ catalyst holding bright prospects for use at a large scale.