Upgrading CO2 from simulated power plant flue gas via integrated CO2 capture and dry reforming of methane using Ni-CaO

Integrated CO2 capture and utilisation via dry reforming of methane (ICCU-DRM) represents a promising and profitable route for directly capturing and converting CO2 from various CO2 sources. However, the influence of realistic flue gas conditions on ICCU-DRM remains unknown and challenging. Herein, we investigated the influence of the presence of H2O and O2 in power plant flue gas on integrated CO2 capture and DRM using Ni10- CaO dual functional material (DFM). It is found that H2O promoted the kinetics of CO2 capture, while the O2 oxidised Ni into NiO and prohibited the performance of utilisation of the captured CO2 during DRM. Specifically, the delay of pre-reduction of NiO and the coverage of catalytic sites by the formed CaCO3 decreased the process performance and efficiency. The reduction of NiO would instantly generate CO2 and hinder the contact between CH4 and Ni, resulting in a lower initial catalytic performance during the CO2 utilisation (DRM) of ICCU. Due to the occurrence of CH4 decomposition in DRM, the following CO2 capture step would produce CO in the flue gas, which could be problematic, owing to the carbon gasification reactions. An extra step of carbon steam gasification (CSG) after DRM could effectively remove most of the deposited carbon and by-produce syngas. Subsequently, the small amount of carbon residue after the CSG step could be preferentially combusted by O2 into CO2 in flue gas, and then be captured by CaO instead of generating CO. This study demonstrates the feasibility and challenges of ICCU-DRM under simulated power plant flue gas conditions and provides potential insights for future investigation and deployment of this integrated process.