Optimized wood-based activated charcoal for desulfurization under realistic biogas conditions

Abstract

This study focuses on the development of a high-performance activated carbon (AC) derived from wood-based charcoal for biogas desulfurization. ACs were densified with eco-friendly binders (cane molasses, beet molasses and plant polyphenols) and impregnated with KI, K₂CO₃, NaOH and KOH at loadings of 5–15 wt%. Both processes enhanced H₂S separation capacity, evaluated through dynamic adsorption tests using a gas mixture composed of N₂, CO₂, O₂ and H₂S, simulating realistic biogas conditions. The best-performing sorbent, AC densified with polyphenol-based binder and impregnated with 10 wt% KOH, was compared to commercial ACs used for biogas desulfurization under identical testing conditions. The developed AC achieved a high H₂S separation capacity of 181 mg g⁻¹ and a competitive volumetric performance of 96 mg cm⁻³, demonstrating strong potential for industrial application. A 1D model for simulating breakthrough curves was developed and validated, using densified AC with CO₂ and O₂ in the feed gas. The model provides accurate predictions and mass transfer coefficients, supporting process design and material optimization. Thermal regeneration at 500 °C under N₂ allowed approximately 50 % of the initial performance to be recovered indicating the need for improved regeneration strategies. The results demonstrate the potential of sustainable, wood-derived AC as a competitive sorbent for industrial biogas purification.