Synergistic removal of CO2, H2S and COS from blast furnace gas with a sulfolane-based biphasic absorbent: performance and mechanism

Abstract

The steel industry faces the dual pressures of carbon reduction and ultra-low emissions throughout production, making integrated CO₂ capture and deep desulfurization of blast furnace gas essential. Conventional alcohol amine-based scrubbing agents have limitations such as low absorption capacity, regeneration difficulties, and high corrosivity. To address these issues, a CO₂, COS (carbon oxysulfide), and H₂S integrated high-efficiency removal biphasic absorbent was developed. The novel biphasic absorbent composed of sulfolane (SF), diethanolamine (DEA), 2-amino-2-methyl-1-propanol (AMP), piperazine (PZ), and H₂O, achieved a removal rate of over 90% for CO₂, COS, and H₂S, under the tested conditions, while exhibiting low rich-phase viscosity and acceptable anti-corrosion performance. Optimal regeneration was attained at 110–120 °C, with regeneration efficiencies exceeding 85% and an estimated energy consumption of approximately 2.51 GJ per ton CO₂ (about 33.9% lower than 30 wt% MEA), while exhibiting stable cyclic regeneration. Spectroscopic analyses (FTIR, ¹H/¹³C NMR) indicate that H₂S undergoes proton transfer to amine sites to form bisulfide containing quaternary ammonium salts, whereas CO₂ and COS react with amine functionalities to yield carbamate and thiocarbamate species that preferentially partition into the aqueous-rich phase; sulfolane remains in the organic phase, enabling liquid–liquid separation. This research provides a promising basis for simultaneous pollution control and CO₂ mitigation in the steel sector, aligning ultra-low emission targets with decarbonization efforts and offering potential environmental and economic benefits.