Impact of sorbent-catalyst layouts on Ru/K-based DFMs for integrated CO2 capture and methanation

Dual Function Materials (DFMs) for integrated CO 2 capture and methanation were investigated to assess the role of the spatial configuration between a Ru-based methanation catalyst and a K-based CO 2 sorbent by combining microreactor experiments and in situ FT-IR spectroscopy. The presence of Ru and K over the same support (i.e., Ru-K/Al 2 O 3 ), as in conventional DFMs, resulted in a significantly higher utilization of the adsorbed CO 2 compared to a physical mixture of segregated Ru/Al 2 O 3 and K/Al 2 O 3 . However, the physical mixture still enabled cyclic operations, achieving complete CH 4 selectivity, unlike Ru-K/Al 2 O 3 . Indeed, the proximity of Ru and K introduced a trade-off between a reduced methanation rate and increased utilization of the captured CO 2 during the cycle. These findings pave the way for the separate optimization of catalyst and sorbent components in integrated CO₂ capture and conversion systems, since the physical mixture outperforms conventional DFMs in some respects. • Physical mixture of Ru/Al 2 O 3 and K/Al 2 O 3 maximizes CH 4 formation rate. • Impregnating K over Ru/Al 2 O 3 maximizes the conversion of adsorbed CO 2 . • Impregnating Ru over K/Al 2 O 3 shows intermediate behavior. • Increasing K content of DFM formulations decreases CH 4 selectivity.