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

Takase A, Kanoh H, Ohba T - Sci Rep (2015)

Bottom Line: The high selectivity of SF6 over N2 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.

View Article: PubMed Central - PubMed

Affiliation: Graduate School of Science, Chiba University, 1-33 Yayoi, Inage, Chiba 263-8522, Japan.

ABSTRACT
SF6 and SF6-N2 mixed gases are used widely as insulators, but such gases have high greenhouse gas potential. The separation of SF6 from SF6-N2 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 N2. 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 N2 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.

No MeSH data available.


Related in: MedlinePlus

(a) Adsorbed densities of N2 (●) and SF6 () in the interstitial nanopores (open symbols) and internal nanopores of CNHs (filled symbols) at 273 K. Selectivity of SF6 over N2 in the interstitial (b), and internal (c) nanopores. The black, red, blue, and green curves represent ySF6:yN2 = 0.1:0.9, 0.3:0.7, 0.5:0.5, and 0.8:0.2, respectively.
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f2: (a) Adsorbed densities of N2 (●) and SF6 () in the interstitial nanopores (open symbols) and internal nanopores of CNHs (filled symbols) at 273 K. Selectivity of SF6 over N2 in the interstitial (b), and internal (c) nanopores. The black, red, blue, and green curves represent ySF6:yN2 = 0.1:0.9, 0.3:0.7, 0.5:0.5, and 0.8:0.2, respectively.

Mentions: The adsorption density results for SF6 and N2 in the interstitial and internal nanopores (shown in Fig. 2a) clearly showed that the SF6 adsorption density was significantly higher in the internal nanopores than in the interstitial nanopores, whereas the N2 adsorption density in the interstitial nanopores was higher than in the internal nanopores, as reported elsewhere28. Here, the adsorption densities were obtained from the number of adsorbed molecules and the micropore volume. The slightly higher density of N2 in the interstitial nanopores was a result of the stronger adsorption potential in the interstitial nanopores, compared with that in the internal nanopores. The significantly lower density of SF6 in the interstitial nanopores was a result of the size restriction imposed by the narrow nanopores, which had a diameter of 0.7 nm. Thus, the adsorption density was controlled by two factors: the adsorption potential, and the steric restriction. These factors led to the highly selective adsorption of SF6 and N2. The selectivity for SF6 over N2 was defined by a theoretical ideal adsorption expression, as follows29:


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

Takase A, Kanoh H, Ohba T - Sci Rep (2015)

(a) Adsorbed densities of N2 (●) and SF6 () in the interstitial nanopores (open symbols) and internal nanopores of CNHs (filled symbols) at 273 K. Selectivity of SF6 over N2 in the interstitial (b), and internal (c) nanopores. The black, red, blue, and green curves represent ySF6:yN2 = 0.1:0.9, 0.3:0.7, 0.5:0.5, and 0.8:0.2, respectively.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4493711&req=5

f2: (a) Adsorbed densities of N2 (●) and SF6 () in the interstitial nanopores (open symbols) and internal nanopores of CNHs (filled symbols) at 273 K. Selectivity of SF6 over N2 in the interstitial (b), and internal (c) nanopores. The black, red, blue, and green curves represent ySF6:yN2 = 0.1:0.9, 0.3:0.7, 0.5:0.5, and 0.8:0.2, respectively.
Mentions: The adsorption density results for SF6 and N2 in the interstitial and internal nanopores (shown in Fig. 2a) clearly showed that the SF6 adsorption density was significantly higher in the internal nanopores than in the interstitial nanopores, whereas the N2 adsorption density in the interstitial nanopores was higher than in the internal nanopores, as reported elsewhere28. Here, the adsorption densities were obtained from the number of adsorbed molecules and the micropore volume. The slightly higher density of N2 in the interstitial nanopores was a result of the stronger adsorption potential in the interstitial nanopores, compared with that in the internal nanopores. The significantly lower density of SF6 in the interstitial nanopores was a result of the size restriction imposed by the narrow nanopores, which had a diameter of 0.7 nm. Thus, the adsorption density was controlled by two factors: the adsorption potential, and the steric restriction. These factors led to the highly selective adsorption of SF6 and N2. The selectivity for SF6 over N2 was defined by a theoretical ideal adsorption expression, as follows29:

Bottom Line: The high selectivity of SF6 over N2 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.

View Article: PubMed Central - PubMed

Affiliation: Graduate School of Science, Chiba University, 1-33 Yayoi, Inage, Chiba 263-8522, Japan.

ABSTRACT
SF6 and SF6-N2 mixed gases are used widely as insulators, but such gases have high greenhouse gas potential. The separation of SF6 from SF6-N2 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 N2. 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 N2 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.

No MeSH data available.


Related in: MedlinePlus