Solubility selectivity-enhanced SIFSIX-3-Ni-containing mixed matrix membranes for improved CO2/CH4 separation efficiency
- 주제(키워드) 도움말 SIFSIX-3-Ni , Chemical stability , Mixed matrix membranes , Carbon dioxide , Gas separations , Monte Carlo simulations
- 발행기관 ELSEVIER
- 발행년도 2021
- 총서유형 Journal
- 본문언어 영어
초록/요약 도움말
The unstable nature of SIFSIX-3-Zn to most organic solvents hinders its application for gas separation albeit its excellent molecular sieving effect and a high affinity towards CO2. Here, we report the enhanced organic solvent resistance of SIFSIX-3-Ni by characterizing their crystallinity and gas adsorption properties after exposure to organic solvents including tetrahydrofuran and N, N-dimethylformaide. SIFSIX-3-Ni microparticles were incorporated into a 6FDA-DAM:DABA (3:2) polyimide (PI) and polysulfone (PSF) matrix to prepare mixed matrix membranes (MMMs) for CO2/CH4 separation. While PI was an unsuitable matrix for high loading MMMs due to the strong hydrogen bonding between the carboxylic groups of PI and the SiF62- anions of SIFSIX-3-Ni, PSF/ SIFSIX-3-Ni MMMs with loading up to 30% were successfully prepared with the aid of the weak interaction between sulfonate groups in PSF and the fluorine atoms of SIFSIX-3-Ni. Interestingly, the CO2 permeability of PSF/SIFSIX-3-Ni MMMs monotonically decreased with increasing CO2/CH4 selectivity as the SIFSIX-3-Ni concentration increased. Also, the PSF/SIFSIX-3-Ni (70/30) MMM showed lower CO2 permeability with higher CO2/CH4 selectivity compared to PSF under an equimolar CO2/CH4 mixed gas condition. Monte Carlo simulations suggest that the strong Coulombic interactions between SIFSIX-3-Ni and CO2 significantly increased the free energy barrier of transport for CO2 over CH4, leading to a reduction in the CO2/CH4 diffusive selectivity of the MMMs. In contrast, the CO2 solubility of PSF/SIFSIX-3-Ni MMMs increased with increasing SIFSIX-3-Ni contents due to the strong interaction between SiF62- of SIFSIX-3-Ni and CO2, significantly enhancing the CO2/CH4 adsorptive selectivity.
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