Improvement on Fluorine Migration from SF6 to SiF4 by an Efficient Mediator of Fe2O3/Cr2O3 Composites

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An economic and facile method was urgently required for the degradation of SF 6 to replace the high-energy excitation treatment. Both theoretical calculations and experimental observations were conducted to reveal the synergy of Cr/Fe/Si composites on a new technique of SF 6 degradation through reacting silicon dioxide. Density functional theory (DFT) calculations show that strong adsorption of SF 6 on Cr 2 O 3, and then the fast F/O exchange between CrF 3 and Fe 2 O 3 (energy barrier was 1.45 eV) as well as FeF 3 and SiO 2 (energy barrier was 1.69 eV) enhanced mediated efficiency from SF 6 to SiF 4 . The fluorine (F) migration between solid interfaces in Cr 2 O 3 &Fe 2 O 3 @SBA15 was responsible for efficient SF 6 removal. The F migration route was composed of SF 6 to CrF 3, CrF 3 to FeF 3, and FeF 3 to SiF 4 with the lowest thermodynamic driving. Enhanced specific accumulative converted amount (SACA) of SF 6 on Cr 2 O 3 &Fe 2 O 3 @SBA15 was achieved and the highest SACA was 13.98 mmol/g within 7 h, significantly higher than that on Fe 2 O 3 @SBA15 (5.74 mmol/g) and Cr 2 O 3 @SBA15 (2.71 mmol/g). Moreover, X-ray diffractometry and X-ray photoelectron spectroscopy were performed to support DFT calculations, including ion intensities detected using mass spectroscopy and composition analysis of the mediator during the reaction. Therefore, our work put forward a novel approach for economic and efficient SF 6 decomposition through reacting with silicon dioxide under the mediation of Cr 2 O 3 &Fe 2 O 3 . This method was also potentially used in effective degradation of refractory non-metal halides.