HF mitigation during liquid metal-based SF6 decomposition via fluorine capture on activated carbon

Sulfur hexafluoride (SF 6 ) is known to generate various partially fluorinated gases and by-products upon decomposition. In this study, a liquid metal system was employed to decompose SF 6 as an air pollution abatement process, achieving an SF 6 decomposition efficiency of 90.74% at 800 °C, with hydrogen fluoride (HF) identified as the predominant gaseous product. To simultaneously capture and mitigate HF, the gas stream was directed over the surface of activated carbon in an integrated post-treatment step. As a result, HF was effectively removed from the exhaust with a removal efficiency of 88.59%, and fluorine was retained on the carbon surface. X-ray photoelectron spectroscopy (XPS) analysis confirmed that the captured fluorine was stably immobilized via C–F bond formation, with characteristics consistent with semi-ionic bonding. A dry-phase method using activated carbon is proposed for the in situ mitigation of HF, the predominant gaseous product formed during SF 6 decomposition. Compared to conventional scrubbing methods that rely on salt-forming reactions (e.g., Ca-based treatments converting HF into CaF 2 ), this approach eliminates the need for aqueous neutralization steps. Moreover, it offers a safer and more environmentally benign pathway for immobilizing reactive fluorine species generated during fluorinated gas abatement. • Liquid tin enabled high SF 6 decomposition efficiency of 90.74% at 800 °C • HF was identified as the dominant gaseous product during decomposition • No sulfuryl fluoride or sulfur oxyfluorides were observed • Activated carbon removed 88.59% of HF via C–F bond formation • An in situ dry-phase approach was proposed for mitigating HF emissions