Hydrogen peroxide-treated glycerol sourced porous carbon with elemental sulfur-based sulfur-phosphorus co-doping for CO₂ capture

In this work, glycerol and elemental sulfur-based porous carbon adsorbents with sulfur‑phosphorus co-doping and subsequent H₂O₂ treatment were developed for CO₂ capture. The best adsorbent for capturing CO₂ among the developed adsorbents was P‑carbon-2000mgS-H₂O₂, which had surface area of 652 m²/g, a total pore volume of 0.446 cm³/g, an average pore size of 2.74 nm, narrow micropore distribution, X-ray photoelectron spectroscopy (XPS)-based sulfur content of 5.7 at.% and phosphorus content of 3.7 at.%, Raman-based average PAHs size of 24.9 Å and a defect density of 4.47 × 10¹¹ cm⁻², and X-ray diffraction (XRD)-based nano-crystallite height of 11.15 Å and length of 23.35 Å. The CO₂ adsorption capacity of P‑carbon-2000mgS-H₂O₂ was 1.95 mmol/g at 25 °C and 1 bar (3.02 mmol/g at 0 °C), and it also demonstrated an impressive CO₂ selectivity over N₂ at 25 °C, with 15.24 at 0.5 bar and 12.03 at 1 bar. In addition to cyclic performance, the isosteric heat of CO₂ adsorption, which was found to be between 22 and 23 kJ/mol, suggested that a physical mechanism predominated the CO₂ interaction with active sites. These findings suggest that employing elemental sulfur to produce glycerol-derived porous carbon with sulfur-phosphorus co-doping and subsequent H₂O₂ treatment is an effective method to produce CO₂ capture adsorbents, facilitating the usage of glycerol and elemental sulfur - based products for large-scale applications.