Effect of Li-Na sorbent phase in Ru/Al2O3 dual function materials for the Integrated CO2 capture and methanation

The design of highly performing dual functional materials (DFMs) is the key to the successful deployment of Integrated Carbon Capture and Methanation (ICCM) process that combines both steps into a single unit operation with high energy efficiency. Intending to enhance the CO2 working capacity while preserving high catalytic methanation activity, herein we set out to investigate the effect of combining Li and Na as the CO2 sorbent phase in Ru/Al2O3 DFMs. ICCM tests in a fixed bed reactor operated with alternate feeds indicated that combining Na with Li (or partially substituting it for Li) effectively increases the CO2 capture capacity and methane production of the DFM. However, this generally requires higher temperatures to properly activate the catalytic methanation and to regenerate the DFM compared to a pure Li-based formulation. Transient operando DRIFTS and catalytic kinetic experiments provided mechanistic insights into the activation/inhibition of different reaction paths on those DFMs containing only Li and/or Na.