Ultrapermeable polymers of intrinsic microporosity (PIMs) for CO2 capture and oxygen enrichment


Schematic representation of the improvement in selectivity and permeability due to the change in the molecular structure
Schematic representation of the improvement in selectivity and permeability due to the change in the molecular structure

Gas separation by polymeric membranes is an energy efficient process used in industry to separate important gas mixtures in the energy and environmental sectors. Membranes for gas separation are also considered as a promising technology for CO2 capture, but for separations on such a massive scale, very high permeability is required to boost the process productivity and make the process economically feasible.

Researchers of the Institute on Membrane Technology (Cnr-Itm) of the National Research Council of Italy, in collaboration with the University of Edinburgh and Cardiff University have demonstrated that fusing rigid and bulky triptycenes to the spiro-centre of a polymer of intrinsic microporosity (PIM) results in large increases in gas permeabilities and gains in selectivities for important gas mixtures compared to the best available commercial membranes.

The paper, published in Advanced Functional Materials, reports the synthesis of a novel polymer, namely PIM-SBI-Trip, and its copolymer with PIM-1 and the analysis of their physical-chemical and gas transport properties. The detailed analysis of the gas transport properties as a function of temperature reveals that the enhanced performance of these polymers is governed by their strong size-sieving character, which can be related to their high rigidity and favours the permeation of smaller gas molecules. Gas separation experiments with CO2/CH4 and CO2/N2 mixtures, simulating biogas and flue gas, respectively show that the transport properties of PIM-SBI-Trip and its copolymer with PIM-1 are only weakly influenced by pressure-changes at a feed pressure up to 6 bar(a). Their excellent performance for the CO2/CH4 and CO2/N2 gas pairs make these novel PIMs particularly promising materials for CO2-related separations, such as biogas upgrading or carbon capture from flue gas. Thus, they may help us in our battle against global warming by reduction of greenhouse gases and by the use of renewable energy. In addition, their outstanding permeability at a similar selectivity as traditional industrially used polymers for the O2/N2 gas pair, makes the novel ultrapermeable 3D polymers promising materials for the to the development of small-scale oxygen generators for medical use in home or hospital by patients with respiratory diseases.

The Cnr-Itm team involved in the study is composed by Alessio Fuoco, Elisa Esposito, Marcello Monteleone, Mariagiulia Longo, Johannes Carolus Jansen.

Per informazioni:
Alessio Fuoco
Cnr - Itm
Johannes Carolus Jansen, Cnr-Itm, tel. +390984-492031, e-mail:

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