Amit M. Shenoy, Raymond Thür, Bart van Duffel and Ivo F.J. Vankelecom of the Membrane Technology Group (MTG), Faculty of Bioscience Engineering, KU Leuven have published a new article entitled Use of green polar aprotic solvents TamiSolve® NxG, DMSO and methyl-THF for the synthesis of asymmetric polyimide-based biogas purification membranes. The article is published in the Journal of Membrane Science, February 2025.
Valorization of biogas to biomethane through membrane-based purification of its multi-component stream primarily consisting of CH4 and CO2, holds significant potential as a crucial renewable energy source. Industrial membrane units classically comprise of membranes synthesized using non-solvent induced phase separation (NIPS), with polymer processing typically performed using conventional solvents, such as N–N-dimethylformamide (DMF), N-methyl-2-pyrrolidone (NMP), etc. However, use and subsequent waste handling of these solvents present significant hazards, due to their toxicological nature, therefore calling for a shift to employ safer and ‘greener’ materials to facilitate sustainable production of these membranes. In current work, a novel and sustainable methodology for synthesis of CO2/CH4 gas separation flat-sheet asymmetric membranes was developed with commercially available Matrimid® 5218 polyimide, using TamiSolve® NxG, dimethylsulfoxide (DMSO) and 2-methyltetrahydrofuran (MeTHF) as green solvent medium. NIPS thermodynamic and kinetic aspects of the novel system were fundamentally analyzed through determination of ternary phase diagrams and viscosity profiles. Membranes were systematically tested for gas separation performance by varying Tamisolve-DMSO-MeTHF solvent ratios. Mixed gas CO2/CH4 separation factors in the range of 13–41, along with CO2 permeances up to 186 GPU were achieved. Furthermore, chemical crosslinking was applied in view of plasticization resistance of the membranes. Matrimid® membranes crosslinked with hyperbranched polyethylenimine (PEI) successfully displayed stability against CO2-induced plasticization up to CO2 feed partial pressures of 22 bar. The developed membrane synthesis method provides a sustainable framework for synthesizing polyimide-based membranes with tunable gas separation performances.
Reference
Amit M. Shenoy, Raymond Thür, Bart van Duffel, Ivo F.J. Vankelecom, Use of green polar aprotic solvents TamiSolve® NxG, DMSO and methyl-THF for the synthesis of asymmetric polyimide-based biogas purification membranes, Journal of Membrane Science, Volume 717, 2025, 123573, ISSN 0376-7388, https://doi.org/10.1016/j.memsci.2024.123573.
Acknowledgement
This work was supported by Fonds Wetenschappelijk Onderzoek (FWO) through project funding in the framework of the Biogas-Mambo project (S003721 N), VLAIO through project funding in the framework of the Moonshot program (SUPREME), and KU Leuven through project funding in the framework of Industrieel Onderzoekfonds (C3/23/017).
