Adsorption capability and regenerability of carbon slit micropores for CO2 capture

Abstract

To date, the exceptional performance of microporous carbon in CO2 capture has been widely acknowledged as a crucial step towards achieving global zero carbon emissions. In this molecular simulation study, we employ grand canonical Monte Carlo simulation (GCMC) to shed light on the significant influence of micropores on CO2 adsorption capability and regenerability, emphasizing the need for a rigorous selection of the swing adsorption process based on pore size. Our findings corroborate numerous experimental and numerical studies that the ultramicropore (pore size < 7 Å) is the appropriate range for CO2 capture, as it facilitates the formation of a horizontal monolayer of CO2 molecules. Furthermore, we highlight the importance of designing porous carbon materials with a large pore volume at the optimal ultramicropore sizes (approximately 5.8-6.4 Å depending on adsorption and desorption conditions) for obtaining high CO2 capture capacity and effective adsorbent regeneration. For the first time, taking into account the operational parameters of practical swing adsorption processes, our simulation study provides valuable guidance for selecting the most appropriate technology tailored to each specific range of micropore size in porous carbon. For porous carbon materials with an abundant volume of ultramicropores, pressure swing adsorption (PSA) and pressure-temperature swing adsorption (PTSA), as conventional and hybrid swing adsorption processes respectively, are the most effective practices, achieving high CO2 working capacity and regenerability exceeding 80%.

Keywords

• CO2 capture
• Porous carbon
• Microporosity
• Adsorption
• Molecular simulation