Adsorption-induced deformation in micro-to-macro-porous media

Abstract

Following the IUPAC recommendation, the pore space in porous materials is divided into three groups according to the pore size diameters: macropores of widths greater than 50 nm, mesopores of widths between 2 and 50 nm and micropores of widths less than 2 nm. Zeolites, activated carbon, tight rocks, cement paste or construction materials are among these materials. In recent years, a major attention has been paid on these microporous materials because the surface-to-volume ratio (i.e., the specific pore surface) increases with decreasing characteristic pore size. These materials can trap an important quantity of fluid molecules as an adsorbed phase. This is important for applications in gas storage, gas separation, petroleum and oil recovery, catalysis or drug delivery.

For these microporous materials, a deviation from standard poromechanics is expected. In very small pores, the molecules of fluid are confined. Fluid-fluid and fluid-solid interactions of molecules are modified and this effect may have significant consequences at the macroscale, such as instantaneous swelling deformations. In different contexts, these deformations may be critical. Generally, natural and synthesized porous media are composed of a double porosity: the microporosity where the fluid is trapped as an adsorbed phase and a meso or a macro porosity required to ensure the transport of fluids to and from the smaller pores. If adsorption in nanopores induces instantaneous deformations at a higher scale, the matrix swelling may close the transport porosity, reducing the global permeability of the porous system or annihilating the functionality of synthesized materials.

People

Current people in the group:

Youssef Khaldouni
PhD Student
Coupling classical DFT with poromechanics for adsorption-induced swelling quantification in microporous materials

(PhD defense in 2022)

Martín P. Rodríguez
Postdoc fellow
Molecular simulation of fluid confinement and crystallisation effects

(24 months 2020/2022)

Alumni:

Laurent Perrier
PhD student
Coupling between adsorption and strain in microporous media

(PhD defense 10-12-2015)Now: Assistant ProfessorLFCR, UPPA

Connected publications

Extended poromechanics for adsorption-induced swelling prediction in double porosity media: modeling and experimental validation on activated carbonNatural and synthesised porous media are generally composed of a double porosity: a microporosity where the fluid is trapped as an adsorbed phase and a meso or a macro porosity required to ensure the transport of fluids to and from the smaller pores. Zeolites, activated carbon, tight rocks, coal rocks, source rocks, cement paste or construction materials are among these materials. In nanometer-scale pores, the molecules of fluid are confined. This effect, denoted as molecular packing, induces that fluid- fluid and fluid-solid interactions sum at the pore scale and have significant consequences at the macroscale, such as instantaneous deformation, which are not predicted by classical poromechanics. If adsorption in nanopores induces instantaneous deformation at a higher scale, the matrix swelling may close the transport porosity, reducing the global permeability of the porous system. This is important for applications in petroleum oil and gas recovery, gas storage, separation, catalysis or drug delivery. This study aims at characterizing the influence of an adsorbed phase on the instantaneous deformation of micro-to-macro porous media presenting distinct and well-separated porosities. A new incremental poromechanical framework with varying porosity is proposed allowing the prediction of the swelling induced by adsorption without any fitting parameters. This model is validated by experimental comparison performed on a high micro and macro porous activated carbon. It is shown also that a single porosity model cannot predict the adsorption-induced strain evolution observed during the experiment. After validation, the double porosity model is used to discuss the evolution of the poromechanical properties under free and constraint swelling.


Connected projects

Newpores - New Frontiers in Porous Materials

Granted by E2S UPPA, NewPores is an international hub dedicated to the mechanics and physics of porous materials, which intends to answer to new Energy and Environment challenges. This is a joint effort of the group on Geomechanics and Porous Materials (G2MP) of the Laboratoire des Fluides Complexes et leurs Réservoirs at E2S UPPA (France), the Centre for Sustainable Engineering of Geological and Infrastructure Materials (SEGIM) at Northwestern University (USA), the University of Vigo (Spain), the Technical University of Madrid (Spain) and University of Liège (Belgium).

I-M-API - Influence in Microporous media of the Adsorbed Phase on Instantaneous and delayed deformations

Granted by the Institut Universitaire de France, the French Carnot Institute Isifor, I-M-API aims at characterising the influence of an adsorbed phase on the instantaneous and delayed deformations in microporous media. Confinement effects will be estimated at the pore nanoscale by efficient DFT-based models, upscaled in enhanced poromechanical frameworks and implemented in simulation tools in order to predict deformation, failure and transport properties of heterogeneous micro-to-macro-porous structures.

CEPAGE - CEPAGE 2 - Couplages adsorption/gonflement en milieu poreux peu perméable

Dans les matériaux microporeux (pores de taille inférieure à 2 nanomètres), les interactions fluide/solide et le confinement augmentent considérablement l’adsorption du fluide, sa densité et donc la pression au sein des pores. Cette surpression peut générer une déformation de gonflement du milieu, entrainer une éventuelle fissuration de la structure, ou au contraire une refermeture du réseau de microfissures existantes. Les projets CEPAGE & CEPAGE2, financés par la région Aquitaine, la communauté d'agglomération de Lacq-Orthez et le Conseil Général 64 visent à mieux décrire les couplages adsorption/gonflement dans les milieux microporeux qui sont également peu perméables. Pour ces milieux, les intérêts sont immédiats, que l’on cherche à garantir une faible perméabilité comme dans les ouvrages de stockage géologique (stockage de CO2 par exemple), ou au contraire que l’on cherche à l’augmenter comme dans l’exploitation responsable des ressources non-conventionnelles ou en géothermie profonde.