Hemin-assisted pore-structure engineering of ZIF-8-derived porous carbons for efficient SF6/N2 separation

Constructing porous carbon adsorbents with SF 6 -matched ultramicropores is an effective route for recovering SF 6 from nitrogen-rich gas streams. Herein, hemin was introduced into ZIF-8 precursors to regulate pyrolysis-induced pore evolution and produce Fe,N-containing porous carbons without corrosive KOH activation. The optimized Fe,N-C-1000 displayed a large BET surface area of 1772.60 m 2 ·g −1 along with abundant ultramicropores mainly distributed at 0.5–0.65 nm, providing suitable confined spaces for adsorption of SF 6 . The Fe,N-C-1000 delivered an SF 6 adsorption capacity of 4.58 mmol·g −1 and an IAST selectivity of 222 at 298 K and 1.0 bar. Fixed-bed breakthrough tests verified the preferential retention of SF 6 over N 2 , as well as good regenerability and cycling stability. Structure-performance analysis suggests that the improved separation performance is mainly governed by hemin-directed ultramicropore formation, while the Fe/N-containing surface environment contributes additionally to SF 6 affinity. DFT calculations further support stronger SF 6 interaction with the Fe,N-C model than with the undoped carbon model. These results demonstrate that hemin-assisted pyrolysis provides a feasible KOH-free strategy for constructing MOF-derived ultramicroporous carbons for the capture and recovery of SF 6 .