Lignin waste-based low-cost porous carbon for efficient and stable CO₂ capture

Developing a low-cost and renewable porous carbon-based CO₂ adsorbent with excellent CO₂ capture capacity, selectivity, stability and low regeneration energy is a contemporary research subject worldwide, especially in the context of a circular and carbon neutral economy. Herein, we report the synthesis of novel low-cost porous carbon materials for highly efficient CO₂ capture prepared from abundant lignin waste via a one-step direct activation/carbonization method. Upon optimization of the activation temperature and activator concentration, the optimal carbon adsorbent material L-K-2–750 with K₂CO₃ as activator, K₂CO₃/lignin mass ratio of 2/3 and activation temperature of 750 °C, exhibited a high specific surface area (797 m²/g) and high total pore volume (0.33 cm³/g). It demonstrated an excellent CO₂ adsorption capacity of 3.75 mmol/g at 25 °C and 1 bar, which is comparable to or better than the CO₂ adsorption capacities reported in the literature (1.1–4.4 mmol/g). Adsorption/desorption cycling experiments revealed excellent stability over five cycles with <2 % loss of adsorption capacity. CO₂/N₂ selectivity experiments showed an excellent selectivity of 57.2 in a CO₂/N₂ mixture (15:85). The Isosteric Adsorption Heat (Q_st) level of 15.9–23.8 kJ/mol confirmed low regeneration energy, thus making this material highly promising for practical applications.

© 2025 The Authors. Published by Elsevier B.V.