High yield and high packing density porous carbon for unprecedented CO2 capture from the first attempt at activation of air-carbonized biomass

Abstract

The first attempt at activation of air-carbonized carbon reveals unusual resistance to activation and unprecedentedly high yields (32–80 wt%) of high packing density (0.7–1.14 g cm⁻³) microporous carbon dominated by 5.5–7 Å pores, which are just right for CO₂ uptake (up to 5.0 mmol g⁻¹) at 1 bar and 25 °C. The high gravimetric uptake and packing density offer exceptional volumetric storage, and unprecedented performance for low pressure swing adsorption (PSA) with working capacity of 6–9 mmol g⁻¹ for a pure CO₂ stream (6 to 1 bar) and 3–4 mmol g⁻¹ for flue gas (1.2 to 0.2 bar). The working capacity for vacuum swing adsorption (VSA) is attractive at 5.0–5.4 mmol g⁻¹ under pure CO₂ (1.5 to 0.05 bar), and 1.8–2.2 mmol g⁻¹ for flue gas (0.3 to 0.01 bar). The pure CO₂ volumetric working capacity breaks new ground at 246–309 g l⁻¹ (PSA) and 179–233 g l⁻¹ (VSA). For flue gas conditions, the working capacity is 120 to 160 g l⁻¹ (PSA). The performance of the activated air-carbonized carbons is higher than the best carbons and benchmark zeolites or MOFs.