A key challenge for material scientists in the area of membrane gas separation is the search for polymers combining high gas permeability coefficients and sufficiently high selectivity, exceeding the so-called Robeson upper bound1. In this work, two strategies were pursued for achieving membranes with improved transport properties. Starting from the archetypal polymer with intrinsic microporosity, PIM-12, novel polymers with a similar rigid backbone and introducing specific groups or functionalities were developed. Thus, innovative nanostructured membranes based on spirobifluorene PIM and an ethanoanthracene-derived Tröger's base PIM were obtained by solution casting. The second approach was focused on nanocomposite or mixed matrix membranes (MMMs) containing different fillers in PIM-1 matrix. MMMs based on open porous nanofillers have the potential to overcome the upper bound by the synergistic action of the highly permeable porous filler and the selective dense polymer matrix. Various metal organic framework (MOF) structures, such as ZIF-8, HKUST-1 and MIL-101, were combined within PIM-1 at different loadings. Pure gas permeation properties were investigated at 25°C and at a feed pressure of 1 bar in a fixed-volume pressure-increase setup in the time lag mode, yielding the permeability and diffusion coefficients for N2, CH4, O2, He, H2 and CO2. Apparent solubility coefficients were indirectly evaluated from the solution-diffusion model. Alcohol treatment (immersion in methanol or ethanol overnight, followed by drying) helped to flush out residual solvent and open up the PIM structure, leading to greatly enhanced permeability. Many of the PIM-1 based MMMs and of the novel PIMs exhibited gas separation performance well above the Robeson upper bound for industrially relevant separations like O2/N2, CO2/N2. The most interesting polymers were also tested in the separation of gas mixtures. Acknowledgments: Project DoubleNanoMem "Nanocomposite and Nanostructured Polymeric Membranes for Gas and Vapour Separations", funded by the European Community's Seventh Framework Programme (FP7/2007-2013) under grant agreement no. NMP3-SL-2009-228631. References 1.L.M. Robeson, J. Membr. Sci. 2008, 230, 390. 2.P.M. Budd et al., J. Membr. Sci. 2008, 235, 851.
Nanostructured and Nanocomposite Polymeric Membranes for Gas and Vapour Separations
Fabio Bazzarelli;Paola Bernardo;Gabriele Clarizia;Johannes C Jansen;
2012
Abstract
A key challenge for material scientists in the area of membrane gas separation is the search for polymers combining high gas permeability coefficients and sufficiently high selectivity, exceeding the so-called Robeson upper bound1. In this work, two strategies were pursued for achieving membranes with improved transport properties. Starting from the archetypal polymer with intrinsic microporosity, PIM-12, novel polymers with a similar rigid backbone and introducing specific groups or functionalities were developed. Thus, innovative nanostructured membranes based on spirobifluorene PIM and an ethanoanthracene-derived Tröger's base PIM were obtained by solution casting. The second approach was focused on nanocomposite or mixed matrix membranes (MMMs) containing different fillers in PIM-1 matrix. MMMs based on open porous nanofillers have the potential to overcome the upper bound by the synergistic action of the highly permeable porous filler and the selective dense polymer matrix. Various metal organic framework (MOF) structures, such as ZIF-8, HKUST-1 and MIL-101, were combined within PIM-1 at different loadings. Pure gas permeation properties were investigated at 25°C and at a feed pressure of 1 bar in a fixed-volume pressure-increase setup in the time lag mode, yielding the permeability and diffusion coefficients for N2, CH4, O2, He, H2 and CO2. Apparent solubility coefficients were indirectly evaluated from the solution-diffusion model. Alcohol treatment (immersion in methanol or ethanol overnight, followed by drying) helped to flush out residual solvent and open up the PIM structure, leading to greatly enhanced permeability. Many of the PIM-1 based MMMs and of the novel PIMs exhibited gas separation performance well above the Robeson upper bound for industrially relevant separations like O2/N2, CO2/N2. The most interesting polymers were also tested in the separation of gas mixtures. Acknowledgments: Project DoubleNanoMem "Nanocomposite and Nanostructured Polymeric Membranes for Gas and Vapour Separations", funded by the European Community's Seventh Framework Programme (FP7/2007-2013) under grant agreement no. NMP3-SL-2009-228631. References 1.L.M. Robeson, J. Membr. Sci. 2008, 230, 390. 2.P.M. Budd et al., J. Membr. Sci. 2008, 235, 851.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
