Microwave-powered integrated carbon capture and utilisation (ICCU) for methane production with rapid temperature response from minimal thermal inertia

• Microwave energy was developed to drive the ICCU-methanation process. • The novel technology shows rapid temperature response from minimal thermal inertia. • A possible rate-enhancing mechanism of the microwave-powered system was proposed. • The microwave-powered CO 2 capture capacity over Ni-CaO-20 DFM was 3.31 mmol g DFM -1 . • CO 2 conversion and CH 4 selectivity reached 71.01% and 98.17% with Ni-CaO-20 DFM. Integrated CO 2 capture and utilisation (ICCU), emerging as an effective approach for achieving global carbon neutrality goals, demonstrates its potential through the transformation of captured CO 2 into valuable methane and the concurrent hydrogen storage via methanation reaction. However, traditional ICCU strategies are heavily reliant on conventional thermal conduction heating, and the in-situ methanation process is constrained by reaction thermodynamics, posing significant challenges. In this study, we introduce for the first time a novel microwave-powered system, employing a clean and efficient energy source that offers rapid heating and on-demand operation and acts as an external field enhancement method in the ICCU-methanation procedure. The designed blend of Ni-loaded CaO and carbon nanotubes (CNTs) integrates the functions of CO 2 adsorption, hydrogenation catalysis, and microwave absorbing ability. This novel approach achieved a CO 2 capture capacity of 3.31 mmol g DFM -1 with CO 2 conversion and CH 4 selectivity reaching 71.01 % and 98.17 %, respectively, at a nickel loading of 20 wt%. We also propose a possible rate enhancement mechanism for the microwave-powered ICCU-methanation cyclic process compared to conventional methods. The microwave-powered system can substantially enhance overall efficiency by swiftly responding to temperature swings, thus reducing processing time in ICCU-methanation cycles.