Single-Component Adsorption Equilibria of CO₂, CH₄, Water, and Acetone on Tapered Porous Carbon Molecular Sieves

Engineered carbon molecular sieves (CMSs) with tapered pores, high surface area, and high total pore volume were investigated for their CO₂, CH₄, water, and acetone adsorption properties at 288.15, 298.15, 308.15 K, and pressures of <1 bar. The results were compared with BPL carbon. The samples exhibited higher adsorption capacity for CO₂ compared to BPL carbon, with Carboxen 1005 being the highest due to the presence of ultramicropores (pores smaller than 0.8 nm). Similar observations were made for CH₄ except at 288.15 K. Although the CMSs exhibited higher hydrophobicity than BPL carbon, the latter had the highest acetone uptake for all investigated temperatures due to its higher oxygen content, which facilitates stronger interactions with polar VOC molecules. Heats of adsorption were calculated using the Clausius–Clapeyron equation after fitting the isotherms with the dual-site Langmuir–Freundlich model, and results largely corroborated the order of adsorption capacities of CO₂, CH₄, and water on the carbon materials.