Membrane polimeriche innovative per pervaporazione e per separazioni avanzate di gas e di vapori

Responsabili di progetto

Johannescarolus Jansen, Pavel Izak

Accordo

REPUBBLICA CECA - CAS (ex AVCR) - Czech Academy of Sciences

Bando

CNR-CAS (ex AVCR) 2016-2018

Dipartimento

Scienze chimiche e tecnologie dei materiali

Area tematica

Scienze chimiche e tecnologie dei materiali

Stato del progetto

Nuovo

Proposta di ricerca

This work proposes a study of two of the 'hottest' materials in materials research in recent years: Ionic Liquids (ILs) and Polymers of Intrinsic Microporosity (PIMs). The first are used as polymer gel membranes with preferential transport for CO2 and the second are suitable as membranes for a wide range of applications. The membrane structure and transport properties will be studied in detail and the correlations between their structure and transport properties will be studied. Results of previous studies were published in well-quoted journals, such as Science, Advanced Materials, Angewandte Chemie, Macromolecules. It was found that a higher stability of the membranes is needed to extend their application to more severe operating conditions. This purpose can be accomplished by using PIMs or other polymer/IL combinations with higher compatibility. The membranes should also have a higher permeation rate, achievable by reducing the selective film thickness. Whereas single gas measurements will give the basic transport properties, the true potential of the membranes in mixed gas permeation measurements must be demonstrated. The performance of these improved systems will be compared with that of conventional supported ionic liquid membranes. These are the main objectives for this project. The research work will therefore focus on three major activity lines, focussing on the topics above, plus dissemination and finally exploration of further possibilities. Instead of a fully experimental approach, in this project there will be also support by powerful modelling methods to study and predict the behaviour of the investigated materials, thus enhancing the understanding and scientific level of the project, favouring a faster achievement of its goals.

1) Membrane preparation and characterization
A systematic study of the optimal preparation conditions will be carried out and the results will be measured in terms of the mechanical, thermal and transport properties of the membranes.
Special focus will be on more stable systems with reduced IL leakage and increased pressure resistance, via the use of charged polymers which stabilize the gel or via chemical cross-linking of the gel forming polymer. In the case of PIMs, special attention will be paid to the reduction of the physical aging.

2) Fundamentals in gas and vapour transport
Studies of the basic transport data will be extended to different temperatures and pressures. Single gas and vapor permeation experiments (mainly CNR) and analysis of pervaporation performance (CAS) will be performed at selected pressures (vapors according to specific vapor pressures; gases from 0 to 5 bar bar) using a highly sensitive time-lag apparatus. For multicomponent mixture permeation experiments, a mass spectrometric gas analyser (CNR) or online FID detector (CAS) will be used. Multicomponent gas-vapor(s) permeation experiments will be performed with "time-lag" cell setup in the first instrument.
Studies of the correlation between transport and mechanical properties will be extended. Transport properties of the membranes will be evaluated, distinguishing the individual contribution of both diffusion and solubility coefficients, and developing more advanced structure-property relationships in a wide range of operating conditions for the new materials.
Experimental work will be supported by modelling of the membrane behaviour at different scales, via Molecular Dynamics (MD) and/or Monte Carlo (MC) simulations, to investigate the properties of the IL/polymer combinations and the PIMs.

3) Applied separations
Thin film composites in flat and/or hollow fibre configurations will be prepared for mixed gas separation experiments, with focus on industrially relevant separations. The optimum structure of the porous support will be investigated via Scanning Electron Microscopy (SEM) analysis of the morphology of the membrane supports, identifying the best structure to assure high flux and selectivity of the final composite membranes. Thin polymer layers of neat PIMs or of polymers containing appropriate amounts of ILs, will be spread on these supports to maximize the permeation rate without losing the separation properties. The compatibility between the thin selective layer and the support will be optimized, while studying new approaches to avoid the penetration of the coating into the support pores.
Mixed gas separation experiments will bridge the gap between the previous single gas data and membrane operation under real conditions. This work will focus on two important applications of industrial interest, namely CO2/CH4 and CO2/N2 separations. The best operation conditions and the optimum membrane compositions will be identified for each application.
The best scoring material will be assembled in small modules in order to increase the membrane surface area, and study the response of the membrane in a practical separation with real gas mixtures.

4) Exploratory work
In the last year, some time may be dedicated to the exploration of other fields of special interest in order to evaluate whether the results may find practical application in different separations or whether other materials can be successful. This concerns:
- Novel applications, such as alkane/olefin separation
- Novel characterization methods, to obtain e.g. currently unavailable data on mixed gas diffusion.
These topics may open possibilities for further collaborations also in international consortia in projects of European interest.

5) Dissemination
A further scope of the project is the dissemination of the research results, publishing at least one manuscript per year in a peer reviewed journal and giving at least two oral presentations/year in international or prestigious national or international conferences.

Obiettivi della ricerca

Further improvement of existing materials is needed to face the main challenges for practical implementation of gas separation membranes via the following objectives:
1) For IL gels: improvement of the membrane stability by the use of charged polymers that interact better with the ionic liquid, reducing leaching phenomena also under severe operating conditions. An alternative approach is the chemical cross-linking of the gel structure.
2) For PIM membranes: reduction of the negative effect of physical aging.
3) Increment of the flux through these membrane systems via the development of composite structures where a porous support will mechanically sustain the thin selective layer of the polymer/IL blend or the PIM. Target systems should avoid pore intrusion by the coating solution and should exceed the performance of conventional supported membranes.
4) Modelling of the materials to achieve a better understanding of the behaviour of the novel materials, to verify the experimental findings and to increase the fundamental knowledge.
5) Module assembly is to increase the surface area and to confirm the practical applicability of the membranes. The latter is also the scope of the mixed gas separation tests, which will give deeper insight into the performance of the membranes under real operation conditions and provide feedback for further optimization of the membrane materials.
The overall aim is the dissemination of results and networking to promote future collaborations

Ultimo aggiornamento: 29/04/2025