Research

Research

Adsorption is a universal phenomenon that can be found in a wide range of domains in science and technology where nanostructured and porous solids play a central role in adsorption based processes. It is essential to be able to both characterize the materials involved and understand the adsorption phenomena in play. My work in the “Separation and Storage of Gases” (S2G) group works to fill gaps in our understanding in these two areas with a focus on societal relevant applications in order to strengthen the link between blue sky research and product development. This responds to one of the Horizon 2020 goals [1].  

From a fundamental standpoint, our knowledge base consists of a four pronged approach :

  • An understanding of adsorption phenomena. Here, in particular, we have developed a hand-in-hand experiment/simulation approach, in which it has been possible to interpret macroscopic experimental data via the use of different theoretical approaches including Density Functional Theory (for local structure analysis), Grand Canonical Monte Carlo (to understand thermodynamics and energies) and Molecular Dynamics (to follow adsorption kinetics).    
  • The characterization of porous solids. This has been our traditional strong point with for example, yearly specialist courses aimed at industrial participation [2] and writing of reference books [3]. Here, recent effort has been made to renew, upgrade and enlarge the panel of apparatus devoted to this topic. 
  • The evaluation of adsorbents for potential applications in gas storage and/or separation. Here we have developed a high throughput screening strategy, which can use as little as 100 mg of sample. The data can be plugged into a database that we are developing and then we can use an Adsorbent Performance Indicator to suggest materials of interest for further evaluation. This evaluation can take the form of larger scale experiments, but also critically, studies int he understanding of the adsorption phenomena with future goals towards the development of structure-property relationships (QSPR).
  • The development of unique methods to address the above axes. A strong point in our work has been the use of microcalorimetry to gain an energetic understanding of the adsorption phenomena and/or material under study. More recently we have coupled calorimetry with structure analysis at large scale facilities (EXAFS, SXRPD) as well as developed a unique calorimetry/poromechanical set-up.  These distinctive experimental approaches are attractive to outside collaborations.

Our unique experimental approaches are the main reason for our attractiveness, which, coupled with our knowledge base has allowed us to develop a number of strategic collaborations both nationally and internationally. These collaborations have been successful in terms of project funding and valorization (high level publications, invited talks, …). Note that several of these projects are coordinated by myself. The research topics that we have focused on in the last few years have essentially replied to Horizon 2020 targets of ‘climate change’ and ‘energy’.

In particular, we have looked at problems surrounding carbon capture. Our group has specialized in the evaluation of novel materials for CO2 recovery. Indeed, the brutal truth is that our hydrocarbon resources (coal, petrol, gas) will continue to be used over the foreseeable future and that there is a crucial need to lower the carbon footprint of a number of key process (cement, steel, electricity production ...). We have positioned our work centrally between experts working on the synthesis of novel metal-organic framework materials and those in process development. Our own strategy has involved (i) the development of a high throughput screening approach in order to obtain adsorption uptakes and initial cycling behaviour with small amounts of material (<100mg) . This allows a selection of materials for (ii) the further characterization of adsorption energies, effect of temperature and prediction of separation properties on upscaled powder materials. The final step allows to choose a limited amount of structures to (iii) make an initial testing of materials which have been made in shaped form.

In our work in the EU MACADEMIA project, we have looked at MOFs for their potential use in natural gas purification where the major contaminant is CO2. Our strategy allowed the consortium to choose 2-3 materials from the 100mg scale for large scale synthesis and shaping which have been tested on the pilot scale.

We have equally studied the effect of water on CO2 capture and we are equally interested in CO recovery which is a problem in steel production for example. In current work, again in the framework of an EU program (M4CO2), we are evaluating MOFs, again using the above strategy, which will be incorporated into mixed MOF-polymer membranes. These will be used in hydrogen production from syngas where the purification stage recovers CO2.  

The group is highly active in the use of nanoporous and nanostructured materials for energy related applications correlated to hydrogen as an energy vector where its storage could be required. Our microcalorimetry measurements at 77K are unique and we are the only group in the world able to directly measure H2 adsorption energies which allows an initial appraisal of materials for hydrogen storage applications. Materials of interest can then be studied at room temperature in terms of adsorption energy and kinetics. In parallel, much effort is devoted to theoretical studies, with Bogdan KUCHTA, to predict which could be the most optimal materials for hydrogen storage applications. This is combined with microcalorimetery experiments (ANR HYSTOR) where effort has been devoted as to how to increase the surface area of graphene related materials as well as how it can be possible to render the surfaces more attractive to hydrogen via the introduction of energetic heterogeneities.

I am equally interested in the use of nanostructured materials for novel mechanical energy applications. Here, flexible MOFs may have the possibility to be used as nanosprings, dampers or shock absorbers depending on their mechanical properties (ANR MODS).

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[1] http://ec.europa.eu/europe2020/europe-2020-in-a-nutshell/priorities/smart-growth/index_en.htm

[2] https://cnrsformation.cnrs.fr/stage.php?stage=15176&axe=54

[3] Adsorption by Powders and Porous Solids, Principles, Methodology and Applications, J. Rouquerol, F. Rouquerol, P. Llewellyn, G. Maurin, K.S.W. Sing, Second Edition (2014), Academic Press, Oxford (G.B.), 646 pages. ISBN−13: 978−0080970356. (web site)

Current projects

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