Ingo Pinnau: Functionalized Polymers of Intrinsic Microporosity for Highly Energy-Intensive Gas Separations (07/21/17)
Membrane-based gas separation is a rapidly emerging technology that has been well established in the purification hydrogen streams, nitrogen production from air and is showing an increasingly larger role in natural gas sweetening and vapor/gas separations. One strategy actively pursued to generate new polymeric membrane materials with combinations of high permeability and high selectivity is the introduction of microporosity (pores < 20 Å) in the polymer matrix. It has been shown that rigid ladder-type chains comprising fused rings joined by sites of contortion pack inefficiently in the solid state to produce polymers of intrinsic microporosity (PIMs). Recently, a successful integration of monomers contorted by spirobisindane, ethanoanthracene, Tröger’s base and triptycene moieties into polyimide structures has generated highly permeable intrinsically microporous polyimides (PIM-PIs). Some of these PIM-PIs exhibited significantly enhanced performance for O2/N2, H2/N2 and H2/CH4 separations with properties defining the most recent 2015 permeability/selectivity upper bounds (Figure 1).
Several series of novel PIM-PIs and ladder PIMs will be presented based on rigid and bicyclic moieties, which are solution processable to form mechanically robust films with high internal surface areas (up to 1000 m2/g). Gas permeation and physisorption data indicate the development of an ultramicroporous structure that is tunable for different gas separation applications. Specific emphasis will be placed on the potential use of hydroxyl- and carboxyl-functionalized PIMs for highly-energy demanding applications for natural gas treatment and olefin/paraffin separation.