Tunable Polyaniline-Based Porous Carbon with Ultrahigh Surface Area for CO2 Capture at Elevated Pressure

Natural gas is the cleanest fossil fuel source. However, natural gas wells typically contain considerable amounts of CO2, with on-site CO2 capture necessary. Solid sorbents are advantageous over traditional amine scrubbing due to their relatively low regeneration energies and non-corrosive nature. However, it remains a challenge to improve the sorbent's CO2 capacity at elevated pressures relevant to natural gas purification. Here, the synthesis of porous carbons derived from a 3D hierarchical nanostructured polymer hydrogel, with simple and effective tunability over the pore size distribution is reported. The optimized surface area reaches 4196 m(2) g(-1), which is among the highest of carbon-based materials, with abundant micro- and narrow mesopores (2.03 cm(3) g(-1) with d < 4 nm). This carbon exhibits a record-high CO2 capacity among reported carbons at elevated pressure (i.e., 28.3 mmol g-1 total adsorption at 25 degrees C and 30 bar). This carbon also shows good CO2/CH4 selectivity and excellent cyclability. Molecular simulations suggest increased CO2 density in micro- and narrow mesopores at high pressures. This is consistent with the observation that these pores are mainly responsible for the material's high-pressure CO2 capacity. This work provides insights into material design and further development for CO2 capture from natural gas.