Fine-tuned ultramicroporous carbon materials via CO₂ activation for molecular sieving of fluorinated propylene and propane

Ultramicroporous carbon materials with precisely engineered pore structures offer a promising pathway for the challenging separation of fluorinated gases with similar physicochemical properties, such as C₃F₆ (fluorinated propylene) and C₃F₈ (fluorinated propane). In this work, we report the synthesis of CO₂-activated porous carbon adsorbents derived from a precursory resin and systematically investigate their molecular sieving behavior for C₃F₆/C₃F₈ mixtures. Through controlled thermal pyrolysis and stepwise CO₂ activation, we tailored ultramicropore size distributions to selectively exclude or admit target molecules. Adsorption studies reveal that optimal CO₂ activation yields pore sizes that enable effective separation of C₃F₆ from C₃F₈, achieving efficient molecular sieving due to size exclusion effects. Excessive activation, however, generates larger pores that diminish selectivity due to nonspecific affinity for both gases. The findings highlight the importance of ultramicropore control for energy-efficient separation of fluorinated hydrocarbons and provide insights for designing advanced adsorbents for industrial gas purification.