Cu‐modified Ni– <scp>CaO</scp> dual‐function materials with tuned <scp>CO</scp> adsorption for enhanced integrated <scp> CO ₂

Abstract

The integrated CO 2 capture and methanation reaction (ICCU‐M) offers a promising route for simultaneous CO 2 capture and direct conversion to CH 4 . However, achieving high CH 4 selectivity remains challenging—particularly at elevated temperatures (>500°C). In this work, introducing Cu into Ni–CaO dual function materials was found to modulate the CO adsorption capacity of Ni sites. As a result, the CH 4 selectivity increased from 93.00% over 5Ni–CaO to 96.77% over 5Ni0.5Cu–CaO at 525°C. Characterization results revealed that Cu incorporation facilitates the formation of a Ni–Cu solid solution, rendering the Ni surface electron‐rich. This electronic modification strengthens CO adsorption and promotes its subsequent hydrogenation to CH 4 . Nevertheless, excessive Cu loading leads to overly strong CO adsorption, which may compete with H 2 adsorption and activation—thereby diminishing CH 4 selectivity. Moreover, in situ DRIFTS results reveal that the direct hydrogenation pathway with HCOO* as a key intermediate species may predominate in the carbonate conversion process.