Pore-Controllable Synthesis of Phthalic Acid-Derived Hierarchical Activated Carbon for Dilute CO₂ Capture

Carbon capture and storage (CCS) from dilute sources is an important strategy for stabilizing the concentration of atmospheric carbon dioxide and global temperature. However, the adsorption process is extremely challenging due to the sluggish diffusion rate of dilute CO₂. Herein, p-phthalic acid (PTA)-derived hierarchical porous activated carbon (PTA-C) with abundant micro- and mesopores was successfully prepared for dilute CO₂ (2 vol %) capture at ambient conditions. The optimal PTA-C sample exhibits an improved BET surface area and total pore volume of 1012.527 m²/g and 2.257 cm³/g, respectively, which endowed a dilute CO₂ (2 vol %) adsorptive capacity of 0.89 mmol/g at 25 °C and atmospheric pressure. The dilute CO₂ adsorptive capacity is increased to 2.71 mmol/g under the same conditions on amine-modified PTA-C (PTA-NC), which is much higher than that of amine-modified commercial coconut husk AC. In addition, the crude p-phthalic acid as feedstocks for production of PTA-C is widely available from polyester fabrics, which makes these PTA-C cost-effective for large-scale CCS from dilute CO₂ sources in industry.