Clathrate hydrates are nanoporous crystalline solids composed of hydrogen-bonded water molecules forming cages within which (gaseous) guest molecules are encapsulated. Since their initial discovery about two centuries ago, interest in clathrate hydrates has grown exponentially from being of mere scientific curiosity to offering a potential new energy solution to the imminent energy crisis. Clathrate hydrates are considered to be pivotal terrestrial and extraterrestrial ingredients, as they make up a great part of the Earth’s seafloor sediments, are involved in gas and oil pipeline blockages, and play a role in extraterrestrial planetary formation scenari. A very important observation common to both terrestrial and extraterrestrial clathrate hydrates is that they are predominantly and naturally formed in the presence of porous dusty ice media, possibly enriched in minerals, hydrated salts and/or sediments. The impact of these mineral impurities onto the physical-chemistry properties of clathrate hydrates (trapped-gas selectivity, thermodynamic promotion or kinetics modification) is of prime importance to track the evolution of the abundances of species taking part in the compositions of hydrate-bearing deposits on Earth and on extraterrestrial bodies. Since the hydrate morphology and distribution both depend on the medium property (chemical composition, hydrophobicity, pore space, bulk stiffness), a fundamental understanding of the hydrate selectivity, thermodynamics, formation and dissociation mechanisms onto/into mineral-like media appears to be crucial. The MI2C project falls in this fundamental research frame and aims at: (i) developing new mixed clathrate hydrates in the presence of mineral defects to mimic their natural environment (e.g., planetary and cometary bodies, deep oceans, permafrost of terrestrial and extraterrestrial origin) and (ii) investigating, at a fundamental level, the underlying factors governing the gas selectivity and formation/dissociation mechanisms in such systems. Consequently, the project encompasses the investigation of mixed clathrate hydrates in thermodynamics conditions relevant to geological and astrophysical environments, and will thoroughly explore the influence of mesoscopic surrogates present in these natural media during clathrate formation. The latter objective constitutes the key novelty of this project.
A wide range of spectroscopic and theoretical tools
To ensure the project’s successful completion, research partners will bring forth an exclusive multidisciplinary approach based on their theoretical and experimental expertise. The research program is designed to integrate a multiscale character ranging from atomic studies (e.g., ab-initio and classical molecular dynamics, Monte Carlo simulations, neutron scattering) to microscopic investigations (high-resolution micro-Raman spectroscopy and imaging, mesoscopic modelling and statistical simulations). This innovative and challenging project falls in the frame of new fundamental perspectives in fields ranging from physical-chemistry (« small scale » deviations from macroscopic thermodynamics laws) to astrophysics or geophysics (« realistic » predictive model for the extraterrestrial and terrestrial observations).