A liquid molten salt catalyst with dynamic active sites for efficient conversion of CO2 to CO

Abstract

The hydrogenation of CO₂ to produce CO via the reverse water–gas shift (RWGS) reaction is an effective pathway for CO₂ capture and utilization. However, the sintering and deactivation issues of solid catalysts are the core challenges limiting the development of this technology. In this work, we develop a liquid molten salt catalyst composed of Li₂CO₃–Na₂CO₃–K₂CO₃, whose inherent fluidity provides a self-renewing gas–liquid catalytic interface for CO₂ capture and conversion, not only achieving a superior performance with 100% CO selectivity and CO yield approaching 100% at 800 °C, but also exhibiting excellent stability over multiple reaction cycles. The catalytic mechanism of the molten salt is associated with an indirect conversion pathway involving the participation of Li₂CO₃, which can be reduced by H₂ to produce CO and LiOH, followed simultaneously by the absorption of CO₂ to replenish the consumed carbonates. The large catalytic interface and the renewable catalytic sites of the liquid catalyst provide a higher CO yield and selectivity compared to conventional solid catalysts, preventing issues of deactivation and aggregation commonly encountered with solid catalysts. This work not only develops a novel liquid molten salt catalyst for CO₂ hydrogenation but also provides valuable insights for the development of efficient CO₂ utilization technology.