Wide Carbon Nanopores as Efficient Sites for the Separation of SF(6) from N(2)

SF(6) and SF(6)-N(2) mixed gases are used widely as insulators, but such gases have high greenhouse gas potential. The separation of SF(6) from SF(6)-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 SF(6) 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 SF(6) 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 SF(6) from the mixed gas.