Optimization of the separation of sulfur hexafluoride and nitrogen by selective adsorption using monte carlo simulations

Abstract

We present molecular simulations to find the optimal conditions for the separation by adsorption of SF 6 from a gaseous mixture with N 2 , a mixture of key interest in electrical applications. The effect of pore size, pressure, and mixture compositions on the selective adsorption of SF 6 was investigated by using Grand Canonical Monte Carlo simulations with simple fluid models and a simplified model of MCM-41. Simulations performed with multisite fluid models confirm that general trends are predicted using simple models, including a maximum in SF 6 selectivity for pore diameters around 1.1 nm. Simulations were also performed using two atomistic models of zeolite-templated carbon (ZTC), FAU-ZTC, and EMT-ZTC, materials with average pore sizes close to 1.1 nm, obtaining high selectivities for both materials. Selectivities for FAU-ZTC are approximately four times higher than the best materials published for this mixture separation, opening excellent opportunities to use it for recovering SF 6 from SF 6 /N 2 mixtures.

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

“…At y SF6 : y N2  = 0.1:0.9, the selectivity was 44 in the internal nanopores at 1 atm, which was equivalent to the greatest selectivity value determined in previous studies, as shown in Table 1111213. Thus, the results of this study indicated that the wide nanopores with large pore volumes provided the greatest selectivity—yielding values similar to the greatest values achieved previously in extremely narrow nanopores, under ambient conditions—although grand canonical Monte Carlo simulations suggested that wide nanopores rarely show separation abilities at high pressures14.…”

“…SF 6 was preferentially adsorbed over N 2 in porous media, because of its strong adsorption potential; in contrast, SF 6 was rarely adsorbed in extremely narrow nanopores81112131415. SF 6 adsorption was rarely observed in zeolites with pores with a diameter of 0.5 nm, but N 2 was adsorbed easily in such narrow nanopores8; in contrast, zeolites with pores with a diameter of 1.0 nm selectively adsorbed SF 6 molecules over N 2 molecules11.…”

“…The hydration of SF 6 and N 2 was also conducted under high pressures10. Motivated by these high costs, adsorption81112131415 and membrane separation9161718 have been proposed as low-energy-cost techniques, and the adsorption technique shows promise for applications in a variety of fields.…”

“…Metal organic frameworks, which have uniform and narrow nanopores, also show highly selective adsorption1213. The pore size dependence of the SF 6 -and-N 2 separation abilities of mesoporous silica and zeolite-templated carbons was evaluated by Builes et al , using grand canonical Monte Carlo simulations14; 1.1 nm-nanopores separated SF 6 and N 2 well. Those preceding studies demonstrated the SF 6 separation efficiency of various porous media having narrow pores, whereas in pores larger than 2.0 nm, the SF 6 and N 2 separation has been neglected.…”

Separation of SF6 from SF6/N2 mixture using metal–organic framework MIL-100(Fe) granule

“…Therefore, efficient methods for the recovery or the decomposition of this gas should be developed because of its long-term effect on the environment [4][5][6].…”