Separation of CO₂ and N₂ from CH₄ is significantly important in natural gas upgrading, and capture/removal of CO₂, CH₄ from air (N₂) is essential to greenhouse gas emission control. Adsorption equilibrium and kinetics of CO₂, CH₄, and N₂ on an ordered mesoporous carbon (OMC) sample were systematically investigated to evaluate its capability in the above two applications. The OMC was synthesized and characterized with TEM, TGA, small-angle XRD, and nitrogen adsorption/desorption measurements. Pure component adsorption isotherms of CO₂, CH₄, and N₂ were measured at 278, 298, and 318 K and pressures up to 100 kPa, and correlated with the Langmuir model. These data were used to estimate the separation selectivities for CO₂/CH₄, CH₄/N₂, and CO₂/N₂ binary mixtures at different compositions and pressures according to the ideal adsorbed solution theory (IAST) model. At 278 K and 100 kPa, the predicted selectivities for equimolar CO₂/CH₄, CH4/N₂, and CO₂/N₂ are 3.4, 3.7, and 12.8, respectively; and the adsorption capacities for CH₄ and CO₂ are 1.3 and 3.0 mmol/g, respectively. This is the first report of a versatile mesoporous material that displays both high selectivities and large adsorption capacities for separating CO₂/CH₄, CH₄/N₂, and CO₂/N₂ mixtures.

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Porous carbon with both high CO 2 uptake and CO 2 /N 2 selectivity is desired for reducing the cost of carbon capture. Here, we report the preparation of N-enriched porous carbons (NPCs) derived from the low-cost triazine-based porous organic polymers using KOH as the activating agent under N 2 . The results indicate that the nitrogen content and textural properties of the NPCs can be effectively adjusted by the polymer precursors and the carbonization temperature. Impressively, the NPCs have an enriched N content (5.56−11.33 wt %) and abundant porosity (BET surface area: 394−1873 m 2 /g, pore volume: 0.27−1.56 cm 3 /g), endowing them with high CO 2 uptake (120− 207 mg/g at 273 K and 1.0 bar) and acceptable CO 2 /N 2 selectivity (Henry's law: 14.3−16.8). In particular, the ultra micropore volume (d ≤ 0.8 nm) is proven a key factor for the CO 2 uptake, while both the ultra micropore volume and N content contribute the CO 2 /N 2 selectivity. Our described work will provide a strategy to initiate developments of rationally designed porous carbons for various potential applications.

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