TY - JOUR
T1 - Removal of Confined Ionic Liquid from a Metal Organic Framework by Extraction with Molecular Solvents
AU - Singh, Manish P.
AU - Dhumal, Nilesh R.
AU - Kim, Hyung J
AU - Kiefer, Johannes
AU - Anderson, James A.
N1 - This work was supported in part by NSF Grant No. CHE-1223988 and by EPSRC Grant No. EP/K00090X/1.
PY - 2017
Y1 - 2017
N2 - Hybrid materials of ionic liquids (IL) confined in metal organic frameworks (MOF) are promising materials for energy storage. The effects of exposing or treating such composite materials with molecular solvents, e.g. with the aim to extract and replace the IL, have not been studied to date. In this study, acetone, isopropanol, methanol, and water were used to remove the IL 1-ethyl-3-methylimidazolium ethyl sulfate confined in a Cu-based metal organic framework (CuBTC). The consequences of the solvent extraction process were analyzed using vibrational spectroscopy (FTIR), powder X-ray diffraction (PXRD), N2 adsorption, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Methanol was identified as the best solvent for IL removal as it shows high extraction efficiency without affecting the porous geometry and crystal structure of the MOF. On the other hand, acetone and isopropanol were not able to completely remove the IL from CuBTC under the conditions employed. Water effectively removed the IL, but it has a significant detrimental effect on the CuBTC structure. This impact manifests as changes in the infrared spectra and the PXRD patterns as well as in the electron micrographs. The degraded CuBTC exhibits a non-porous structure that presents itself as non-uniformly agglomerated micro-rods along with very few hexagonal/amorphous phases. The confinement of acetone, isopropanol, and methanol in the MOF was also investigated. The results show that CuBTC is stable in acetone, isopropanol, and methanol but unstable in water.
AB - Hybrid materials of ionic liquids (IL) confined in metal organic frameworks (MOF) are promising materials for energy storage. The effects of exposing or treating such composite materials with molecular solvents, e.g. with the aim to extract and replace the IL, have not been studied to date. In this study, acetone, isopropanol, methanol, and water were used to remove the IL 1-ethyl-3-methylimidazolium ethyl sulfate confined in a Cu-based metal organic framework (CuBTC). The consequences of the solvent extraction process were analyzed using vibrational spectroscopy (FTIR), powder X-ray diffraction (PXRD), N2 adsorption, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Methanol was identified as the best solvent for IL removal as it shows high extraction efficiency without affecting the porous geometry and crystal structure of the MOF. On the other hand, acetone and isopropanol were not able to completely remove the IL from CuBTC under the conditions employed. Water effectively removed the IL, but it has a significant detrimental effect on the CuBTC structure. This impact manifests as changes in the infrared spectra and the PXRD patterns as well as in the electron micrographs. The degraded CuBTC exhibits a non-porous structure that presents itself as non-uniformly agglomerated micro-rods along with very few hexagonal/amorphous phases. The confinement of acetone, isopropanol, and methanol in the MOF was also investigated. The results show that CuBTC is stable in acetone, isopropanol, and methanol but unstable in water.
U2 - 10.1021/acs.jpcc.7b02289
DO - 10.1021/acs.jpcc.7b02289
M3 - Article
VL - 121
SP - 10577
EP - 10586
JO - The Journal of Physical Chemistry C
JF - The Journal of Physical Chemistry C
SN - 1932-7447
IS - 19
ER -