Manipulation of CO₂ hydrogenation selectivity over RuSn/La₂O₂CO₃ catalysts with intermetallic electron transfer

Selective hydrogenation of CO₂ to syngas via the reverse water–gas shift (RWGS) route provides an effective strategy to achieve low-carbon development. While CO₂ methanation to CH₄ takes place readily on Ru metal, the selective hydrogenation of CO₂ to CO in Ru-catalysts remains a challenge. In this work, we prepared a Ru-Sn/La₂O₂CO₃ catalytic system allowing over 99% selectivity of CO during CO₂ hydrogenation at 400 °C. Characterization revealed that the transfer of electrons from Sn to Ru weakened the dissociation ability of H₂ while improving the adsorption ability of O on Ru. The former inhibited the formation of methane, while the latter caused the C-O bond energy of CO₂ adsorbed at the Ru-Sn interface to decrease and dissociate at the Ru-side, forming Ru-CO* and Ru-O*; thus, realizing the RWGS process. An ultra-low Ru-loaded (0.01 wt%) RuSn/La₂O₂CO₃ catalyst with strong metal-support interactions achieved a CO₂ hydrogenation rate at 10³ times higher than the best reported data. This catalyst was successfully applied to the hydrogenation of blast furnace gas (BFG) to syngas, showing a CO formation rate as high as 2.3*10⁶ mmol_CO·g_Ru⁻¹·h⁻¹ and remaining stable at 850 °C for 1000 h.