New PhD Project Offers
2012-20-LF Nanocomposite Membranes for CO2 separation (UW-WIN, UB1-LCPO)
There is growing concern about CO2 emissions, especially from the fossil fuel powerplants which are the main emitters of this green house gas that presents a very long residence time in the atmosphere (around 100 years). Nevertheless, the recent concerns about the nuclear powerplants, and decisions in several countries to reduce this resource for energy production, will lead to the parallel development of fossil fuel power plants. In addition, China is building two new powerplants every week, which means that the CO2 emissions will not decrease within the next years. Therefore, if CO2 emissions cannot be reduced, it becomes of great importance that CO2 emissions could be captured and CO2 could be used as a resource for a more cyclical production mode, the key for sustainable processes.
However, any real solution must take into account the enormous volume of flue gas that is emitted by a single power plant, around 2 Millions of m3 per hour! As a result, any potential solution must integrate from the beginning the potential scale-up toward industrial technologies and/or the parallel adaptation of current industrial products to this application.
Until now, the only pilot plants that have been tested are based on amine scrubbing, but the actual development of this chemical process seems to be a dead-end, once the actual scaling-up will be required (capture of one ton of CO2 involves the parallel release of one kilo of amine back to the atmosphere). Other absorption methods based on new materials (Metal Oxide Frameworks) are studied, but it seems difficult to imagine them going out from the laboratory or being used in domains other than niche applications, regarding the production cost and the tremendous mass that would be required.
Membrane processes appear as being potentially good candidates and their development has been strongly supported by the European Union (nanoGLOWA program). However, the requirements for an effective CO2 separation from air, with membranes, is still facing several challenges: a very high selectivity is required if one wants to allow a cost effective sequestration or storage, but this selectivity can be provided only by dense polymer membranes. However, polymer membranes have a rather low permeability, and realistic flux can be observed only at the expenses of a higher pressure difference between retentate and permeate (several bars), a solution that is hardly compatible with end-users needs, since the whole flue gas emitted at around one bar, should be compressed at 3-5 bars for an efficient process.
One solution that has been studied was to reduce the thickness of the polymer membrane from several microns (current) to a few hundred of nanometers, to allow for a higher flux, but this method, if it works well for very small surfaces (some cm2), becomes extremely difficult to be scaled-up, due to the creation of defects (eg. pin-holes) that destroy the overall performance of these membranes. On the other side, ceramic membranes have been demonstrated to be extremely suitable for high gaseous flux, as they are porous, but trials to improve their selectivity toward CO2, has blocked onto two major drawbacks: a limited CO2/N2 selectivity of 8-10 for ceramic membranes prepared at the laboratory scale, and specifically modified; the almost impossible difficulty to achieve at the industrial scale, a minimum level of defects to achieve the performances observed in the laboratory.
Our research project takes as a starting point the current knowledge on membrane-based CO2 separation, and intends to develop an innovative solution, based on the modification at the nanoscale, of commercial ceramic membranes in order to combine the qualities of both (polymer and ceramic) products and to allow for the preparation of nanocomposite polymer/ceramic membranes where the actual membrane will be a thin polymer film to allow for high selectivity, supported on a commercial tubular ceramic. The key point is such a material, will be the adhesion of the polymer membrane onto the ceramic support: usual coating/dipping procedures cannot apply for large scale development, as they will create defects. Hence, the polymer membrane must grow directly from the metal oxide ceramic surface, in order to provide a strong connection and a robust material. We have already validated the mechanism and we have demonstrated that a specific polymer film can grow onto the surface of a ceramic membrane that was potentially modified by the additional creation of an additional layer made of commercial nanoparticles.
The research program will cover the following steps: (i) development of polymer films onto tubular ceramic membranes that can be modified by the addition of a layer of nanoparticles, (ii) study of the reaction parameters that control the growth and thickness of the polymer membrane, (iii) study of the performances of such membranes (as a function of different structural parameters) in gas separation (especially CO2), (iv) extension of the process to other polymers (collaboration with the LCPO), (v) study in close collaboration with the industrial partners, of the development for scale-up production, (vi) transfer of the knowledge to the preparation of similar materials on ceramic hollow fibers and/or ceramic honeycombs (to be defined with partners), (vii) possible extension toward pilot.
Dept for Chem Engineering, University of Waterloo (UW-WIN, Canada),
- Synthesis of membranes and separation tests
Laboratoire de Chimie des Polymères Organiques, Université Bordeaux 1 / ENSCPB (LCPO-UB1, France)
- application of the method to other polymers
Laboratory of Future, Solvay-Rhodia, Bordeaux, France
- development of organic-inorganic nanocomposite membranes toward other applications area than CO2 separation
Ceramiques Techniques Industrielles (CTI sas), Salindres, France
- ceramic and polymer membranes
Specific Polymers, Clapiers France
- "taylor-made" synthesis of functional polymers