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

Abstract

The hydrogenation of CO2 to produce CO via reverse water-gas shift (RWGS) reaction is an effective pathway for CO2 capture and utilization. However, the sintering and deactivation issues of the solid catalysts are the core challenge limiting the development of this technology. In this work, we develop a liquid molten salt catalyst composed of Li2CO3-Na2CO3-K2CO3, of which 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 approach to 100% at 800 °C, but also exhibiting excellent stability over multiple reaction cycles. The catalytic mechanism of molten salt is associated with an indirect conversion pathway involving the participation of Li2CO3, of which can be reduced by H2 to produce CO and LiOH, simultaneously followed by the absorption of CO2 to replenish the consumed carbonates. The large catalytic interface and the renewable catalytic sites of liquid catalyst provides a higher CO yield and selectivity than the 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.