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Pavleta Knutsson
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Article · High-temperature corrosion and ash · Porous carbons and CO2 capture

Tailoring highly surface and microporous activated carbons (ACs) from biomass via KOH, K₂C₂O₄ and KOH/K2C2O4 activation for efficient CO₂ capture and CO2/N2 selectivity: characterization, experimental and molecular simulation insights

B. Dziejarski, J. Serafin, D. F. Hernández-Barreto, E. Naumovska, J. Sreńscek-Nazzal, N. Klomkliang, E. Tam, R. Krzyżyńska, K. Andersson, P. Knutsson

Chemical Engineering Journal 524, 169677 (2025) · 62 citations

DOI 10.1016/j.cej.2025.169677Open access

In plain language

Carbons from pine wood that capture CO2

Pine wood activated at 800 °C with KOH, K2C2O4 or mixtures of the two. Co-activation gave a surface area of 2029 m2/g; the KOH carbon reached the highest CO2 uptake (9.65 mmol/g at 0 °C), while the K2C2O4 carbon gave the best CO2/N2 selectivity. Molecular simulations link the performance to sub-nanometre pores and carbonyl-rich surfaces.

Abstract

The environmental impact of wood waste disposal and limitations of conventional chemical activation underscore the need for sustainable strategies to convert lignocellulosic biomass into efficient CO₂ sorbents. In this study, pine wood was activated at 800 °C using KOH, K₂C₂O₄, and their mixtures (mass ratios 1:1 to 1:4) to tailor porosity and surface chemistry for selective CO₂ capture. Co-activation at a 1:2:2 ratio (biomass:KOH:K₂C₂O₄) delivered optimal textural features, including a BET surface area of 2029 m 2 /g, total pore volume of 1.028 cm 3 /g, and micropore volumes of 0.923 cm 3 /g (N₂) and 0.156 cm 3 /g (CO₂). The KOH-activated carbon (1:1) achieved the highest CO₂ uptake 9.65 mmol/g at 0 °C and 5.95 mmol/g at 25 °C due to extensive ultramicropore development. In contrast, the K₂C₂O₄-derived sample (1:4) exhibited lower uptake (8.79 mmol/g at 0 °C) but superior CO₂/N₂ selectivity (>21 at 5 % CO₂, 1 bar), linked to narrower pores and higher surface polarity. Structural and surface analyses (XRD, FTIR, XPS, XRF, SEM, TGA) confirmed turbostratic carbon, abundant oxygenated groups (C O, C O), and sponge-like morphology with residual inorganic species. Isosteric heats of CO₂ adsorption (26–36 kJ/mol) indicated strong physisorption, and isotherm modeling identified Radke–Prausnitz as the best-fit model. Grand canonical Monte Carlo simulations supported the experimental results, revealing that sub-nanometer pores and carbonyl-rich surfaces enhance CO₂ affinity. This work presents a comprehensive comparison of K-based activation strategies and demonstrates that co-activation offers a scalable, less harsh route to high performance porous carbons for CO₂ capture. • Pine wood was activated with KOH, K₂C₂O₄, and their mixtures at 800 °C. • Co-activation (1:2:2) produced balanced porosity and high CO₂ uptake. • CO₂ adsorption reached 9.65 mmol/g at 0 °C and 5.95 mmol/g at 25 °C. • K₂C₂O₄ activation gave the highest CO₂/N₂ selectivity (21–54 via IAST). • GCMC analysis revealed carbonyl-rich ultramicropores enhance CO₂ affinity.

Abstract as indexed by OpenAlex.

BibTeX

@article{dziejarski-2025-tailoring-highly-surface,
  author  = {Dziejarski, B. and Serafin, J. and Hernández-Barreto, D. F. and Naumovska, E. and Sreńscek-Nazzal, J. and Klomkliang, N. and Tam, E. and Krzyżyńska, R. and Andersson, K. and Knutsson, P.},
  title   = {Tailoring highly surface and microporous activated carbons (ACs) from biomass via KOH, K₂C₂O₄ and KOH/K2C2O4 activation for efficient CO₂ capture and CO\textsubscript{2}/N\textsubscript{2} selectivity: characterization, experimental and molecular simulation insights},
  journal = {Chemical Engineering Journal},
  year    = {2025},
  volume  = {524},
  pages   = {169677},
  doi     = {10.1016/j.cej.2025.169677}
}