Mitigating the Poisoning Effect of Formate during CO ₂ Hydrogenation to Methanol over Co-Containing Dual-Atom Oxide Catalysts

Abstract

During the hydrogenation of CO₂ to methanol over mixed-oxide catalysts, the strong adsorption of CO₂ and formate poses a barrier for H₂ dissociation, limiting methanol selectivity and productivity. Here we show that by using Co-containing dual-atom oxide catalysts, the poisoning effect can be countered by separating the site for H₂ dissociation and the adsorption of intermediates. We synthesized a Co- and In-doped ZrO₂ catalyst (Co-In-ZrO₂) containing atomically dispersed Co and In species. Catalyst characterization showed that Co and In atoms were atomically dispersed and were in proximity to each other owing to a random distribution. During the CO₂ hydrogenation reaction, the Co atom was responsible for the adsorption of CO₂ and formate species, while the nearby In atoms promoted the hydrogenation of adsorbed intermediates. The cooperative effect increased the methanol selectivity to 86% over the dual-atom catalyst, and methanol productivity increased 2-fold in comparison to single-atom catalysts. This cooperative effect was extended to Co-Zn and Co-Ga doped ZrO₂ catalysts. This work presents a different approach to designing mixed-oxide catalysts for CO₂ hydrogenation based on the preferential adsorption of substrates and intermediates instead of promoting H₂ dissociation to mitigate the poisonous effects of substrates and intermediates.