Polymer based ionic liquid gel membranes for gas and vapour separations
J.C. Jansen1, P. Bernardo1, F. Bazzarelli1, G. Clarizia1, F. Tasselli1, A. Fuoco1, K. Friess2, J.
Schauer3, V. Jarmarová4, M. Kacirková4, P. Izák4
1
Institute on Membrane Technology, ITM-CNR, Via P. Bucci 17/C, 87030 Rende (CS), Italy.
E-mail: jc.jansen@itm.cnr.it. Tel +39 0984-492031, Fax. +39 0984-402103. 2 Institute of
Chemical Technology Prague, Technická 5, 166 28 Prague 6 – Dejvice, Czech Republic.
3
Institute of Macromolecular Chemistry, Heyrovského nám. 2, 162 06 Prague 6 – Břevnov,
Czech Republic. 4 Institute of Chemical Process Fundamentals, Rozvojová 135, 165 02
Prague 6 - Suchdol, Czech Republic.
In the last decades membrane operations are becoming increasingly important for industrial
gas and vapour separation processes [1]. Polymers form the most abundant class of materials
used for commercial membrane preparation. An important limitation of polymeric membranes
is the trade-off between their permeability and their selectivity [2]. Among the various
approaches to overcome this limitation, the incorporation of room temperature ionic liquids
(RTILs) into polymer membranes offers a promising opportunity for optimization of the
membrane performance [3].
Recently we found that membranes of 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIM][TFSI]) in poly(vinylidene fluoride-co-hexafluoropropylene)
(poly(VDF-co-HFP)) have a particularly interesting CO2/H2 selectivity [4]. In the present
study we will present these and other polymeric membranes with tailored gas and vapour
transport properties by addition of variable amounts of RTILs, up to at least 80 wt.%.
Different polymer matrices and different ILs will be studied. The materials choice will be
based on their mutual compatibility and their ability to form self-standing membranes, for
instance in the form of stable gels. It will be shown that the separation performance and
transport properties of such membranes can be correlated with important structural properties
such as the elastic modulus, enabling the easy visualization of the transition from diffusion
controlled to solubility controlled permeation (Figure 1).
80
1000
60
40
20
0
Composition
(wt.% IL)
CO2
Permeability (Barrer)
100
10
1
He
H2
CO2
0.1
Solubility controlled
permeation
0.01
Diffusion controlled
permeation
CH4
O2
N2
0.001
1
10
100
1000
10000
Young's modulus (MPa)
Figure 1. Correlation between permeability and Young's modulus for a polymer gel
membrane with 80% of ([EMIM][TFSI]) in poly(VDF-co-HFP) [4].
The membrane properties will be studied by single gas permeation measurements to
determine the basic transport parameters (permeability, solubility and diffusivity), and by
mixed gas and gas/vapour permeation measurements to determine their actual separation
performance under representative conditions. In addition to self-supported dense membranes,
also supported thin film composite membranes will be evaluated. Their performance will be
discussed in view of important industrial applications.
Acknowledgements: Funding was received from the European Community's Seventh
Framework Programme (FP7/2007-2013) under grant agreement no. NMP3-SL-2009-228631,
project DoubleNanoMem, from the Czech Science Foundation (Grant No. P106/10/1194) and
from the CNR-CAS bilateral agreement 2010-2012.
References
1. P. Bernardo, E. Drioli, G. Golemme, Membrane gas separation. A review / State of the art,
Ind. Eng. Chem. Res. 2009, 48, 4638.
2. L. M. Robeson, The upper bound revisited, J. Membr. Sci., 2008, 320, 390.
3. P. Scovazzo, Determination of the upper limits, benchmarks and critical properties for gas
separations using stabilized room temperature ionic liquid membranes (SILMs) for the
purpose of guiding future research, J. Membr. Sci. 2009, 343, 199.
4. J.C. Jansen, K. Friess, G. Clarizia, J. Schauer, P. Izák, High ionic liquid content polymeric
gel membranes: preparation and performance. Macromolecules 2011, 44, 39-45.
5. K. Friess, J.C. Jansen, F. Bazzarelli, P. Izák, V. Jarmarová, M. Kačírková, J. Schauer, G.
Clarizia, P. Bernardo, High ionic liquid content polymeric gel membranes: correlation of
membrane structure with gas and vapour transport properties, Submitted.