Wide Carbon Nanopores as Efficient Sites for the Separation of SF6 from N2

SF6 and SF6-N-2 mixed gases are used widely as insulators, but such gases have high greenhouse gas potential. The separation of SF6 from SF6-N-2 mixed gases is an inevitable result of their use. Single-walled carbon nanohorns (CNHs) were used here for a fundamental study of the separation of SF6 and N-2. The diameters of the interstitial and internal nanopores of the CNHs were 0.7 and 2.9 nm, respectively. The high selectivity of SF6 over N-2 was observed only in the low-pressure regime in the interstitial 0.7 nm nanopores; the selectively was significantly decreased at higher pressures. In contrast, the high selectivity was maintained over the entire pressure range in the internal 2.9-nm nanopores. These results showed that the wide carbon nanopores were efficient for the separation of SF6 from the mixed gas.