Sorption and permeation studies of novel PIMs for CO2/CH4 separation

During the last four decades, membrane-based processes have become an important separation technique in the chemical and process industry. An application of recent interest, driven by the increasing need for sustainable energy production and use, involving the CO2/CH4 separation, is the recovery of pure methane from crude biogas. Polymers of intrinsic microporosity (PIMs), a novel class of polymeric materials introduced about a decade ago, have shown interesting perspectives as effective gas and vapour separation membranes due to their unique structural properties.1, 2 In view of the above mentioned CO2/CH4 separation, an extensive study of the effect of structural variations in PIMs on their carbon dioxide and methane sorption properties is presented. Sorption properties of PIM-13,4 and five of its analogues (PIM-PI-SBI5, PIM-PI-EA5, PIM-EA-TB6, PIM-Triptycene-TB6 and Amine-PIM-17) were studied. The experiments were performed gravimetrically at 25°C in a pressure range of 1 to 7 bar, using a calibrated McBain's quartz spiral balance.8 The sorption isotherms and sorption kinetics were parameterized with the dual mode sorption model, yielding quantitative values of the sorption (S) and diffusion (D) coefficients 9 and the ideal sorption selectivity (?x/y) of the CO2/CH4 gas pair. The results revealed that targeted structural changes in the polymers allow tailoring of their sorption properties over a wide range. Comparison of the results with the transport properties determined by permeation measurements and time-lag analysis allow the identification of anomalous transport phenomena, and confirm the unique nature and great potential of polymers of intrinsic microporosity. Acknowledgements The work leading to these results has received funding from the European Union Seventh Framework Programme (FP7/2007-2013) under grant agreement no. NMP3-SL-2009-228631 "DoubleNanoMem", from the Italian Programma Operativo Nazionale Ricerca e Competitività 2007-2013, project PON01_01840 "MicroPERLA" and the Grant Agency of the Czech Republic, Grant No. 106/10/1194. References 1. N. B. McKeown and P. M. Budd, Macromolecules, 43, 5163 (2010). 2. O. Vopi?ka, K. Friess, V. Hynek, P. Sysel, M. Zga?ar, M. ?ípek, K. Pilná?ek, M. Lan?, J.C. Jansen, C.R. Mason and P.M. Budd, J. Membr. Sci., 434, 148 (2013). 3. P. M. Budd, E. S. Elabas, B. S. Ghanem, S. Makhseed, N. B. McKeown, K. J. Msayib, C. E. Tattershall and D. Wang, Adv. Mater. 16, 456 (2004). 4. P. M. Budd, K. J. Msayib, C. E. Tattershall, B. S. Ghanem, K. J. Reynolds, N. B. McKeown and D. Fritsch, J. Membr. Sci. 251, 263 (2005). 5. Y. Rogan, R. Malpass-Evans, M. Carta, J.C. Jansen, P. Bernardo, G. Clarizia, E. Tocci, K. Friess, M. Lan? and N.B. McKeown, Adv. Mater., (2014) in press. 6. M. Carta, M. Croad, R. Malpass-Evans, J.C. Jansen, P. Bernardo, G. Clarizia, K. Friess, M. Lan? and N.B. McKeown, J. Mater. Chem. A, (2014) in press. 7. C.R. Mason, L. Maynard-Atem, K.W.J. Heard, B. Satilmis, P.M. Budd, K. Friess, M. Lan?, P. Bernardo, G. Clarizia and J.C. Jansen, Macromolecules, 47, 1021 (2014). 8. K. Friess, J.C. Jansen, O. Vopi?ka, A. Randová, V. Hynek, M. ?ípek, L. Bartovská, P. Izák, M. Dingemans, J. Dewulf, H. Van Langenhove and E. Drioli, J. Membr. Sci., 338, 161 (2009). 9. O. Vopi?ka, V. Hynek, M. Zga?ar, K. Friess and M. ?ípek, J. Membr. Sci., 330, 51 (2009).