Porous carbon pellets for physical adsorption of CO2: size and shape effect†

The continuous rise in atmospheric CO₂ level is a major concern, demanding the development of low-cost, scalable porous sorbents with improved efficiency and recyclability. The current chemical adsorption methods are energy-intensive, creating a demand for low-energy CO₂ capture/removal strategies. Physical adsorption of CO₂ offers an efficient and low-energy alternative. This study explores the design and screening of porous carbon pellets for physical adsorption of CO₂ from 15% CO₂ in N₂ at 30 °C. Various sizes of spherical pellets were designed and investigated for their effect on adsorption capacity and kinetics. Changing the shape from spherical to flakes increased the CO₂ adsorption capacity to 2.2 wt% (0.5 mmol g⁻¹). The pellets were also analysed for cyclic adsorption–desorption to access long-term stability and recyclability, showing approximately 80% selectivity for CO₂ over N₂ over 20 cycles.