Production of activated carbons from corn cobs waste by steam or H3PO4 activation for effective CO2 capture and industrial gas selectivity towards CO2/CH4/N2

Journal article, 2026

This study compares physically and chemically activated carbons (ACs) derived from corn cobs for CO2 capture, focusing on their adsorption performance, selectivity and stability. Chemically activated AC-CC-C-800 exhibited the highest CO2 adsorption capacity, reaching 7.46 mmol/g at 1 bar and 25 °C and with a specific surface area of 1678 m²/g. In contrast, physically activated AC-CC-P-800 showed lower adsorption equal to 5.59 mmol/g but a more uniform pore structure with a specific surface area of 1546 m²/g, maintaining a high stability over 30 adsorption–desorption cycles. While chemical activation produced a higher microporosity, it required strong activating agents, making the process less environmentally friendly and generating chemical waste. Physical activation, using only steam at high temperatures, resulted in cleaner production with lower environmental impact while maintaining sufficient CO2 adsorption capacity and selectivity. Structural analysis using X-ray spectroscopy (XRD), Raman spectroscopy, and Scanning Electron Microscopy (SEM) confirmed the differences in porosity and surface properties between both methods. CO2/CH4/N2 gas selectivity in industrial applications were analyzed, including steel industry emissions, steam gasification and ammonia production. The findings highlight that physically activated ACs, despite slightly lower adsorption, offer a more sustainable and scalable solution for industrial CO2 capture, balancing efficiency with eco-friendly processing.