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Reference : UMR5275-FABCAR-024
Workplace : GRENOBLE
Date of publication : Friday, October 25, 2019
Type of Contract : FTC Scientist
Contract Period : 18 months
Expected date of employment : 1 January 2020
Proportion of work : Full time
Remuneration : 2617€ gross salary
Desired level of education : PhD
Experience required : Indifferent
Significant amounts of hydrogen may remain trapped in the near and far field of the nuclear waste disposal sites. Sorption process may drastically impact hydrogen mobility in the geological environment. Clay minerals and clay-rich rocks offer the ideal substrates for H2 sorption due to their high surface area, high density of bending site exposing H2 to overlapping potential and pore size closely matching the H2 kinetic diameter (~6 Å). Hydrogen uptake by dry smectites and callovo-oxfordian claystone is in the range of 4000 ppm at 40 bar H2 partial pressure and 20°C (Didier, 2012, Bardelli et al., 2014; Mondelli et al., 2012). Recent investigations have demonstrated that natural water saturated clay-rich rock may contain up to 500 ppm of H2 (Truche et al., 2018). Such H2 uptake is equivalent to CH4 capacities of organic-rich shales exploited by fracking by the oil&gas industry (Ross and Bustin, 2009). This process may contribute to mitigation of hydrogen overpressure and thus the mechanical stress applied on the host-rock.
- Our objective is to quantify hydrogen uptake by clay-rich rocks and to evaluate the stability of this process with respect to several perturbations (e.g., temperature, water re-saturation, secondary minerals precipitation).
- We will combine sorption experiments with molecular dynamics computer simulations to quantify and understand H2 physisorption mechanisms in micro- and nano-porous clay systems.
- The selected candidate will measure hydrogen uptake by clay minerals (e.g. montmorillonite, illite, chlorite, Fe-serpentine) and clayrocks (bentonite, Callovo-Oxfordian claystone, Boom clays and Opalinus clays) as a function of H2 partial pressure, temperature, water saturation (relative humidity), and presence of other gases competing for sorption (CO2, CH4, He). Experiments will be performed both on intact and powdered samples.
- He/she will measure H2 sorption isotherms over a wide range of pressure (typically from 1 mbar to 100 bar) to study the retention mechanisms and fundamental thermodynamic properties of the retention process (adsorption enthalpy, role of pore size distribution, crystallographic properties of the sorption sites).
- He/she will also study the desorption processes to clearly evaluate hydrogen mobility and retention mechanisms in clay-rich porous media. We will use N2 adsorption at 77 K, thermal desorption coupled to GC, high-pressure autoclaves, and QENS neutron scattering (ILL, Grenoble) techniques to perform these measurements.
- Based on the previous extensive research experience of our team (e.g., Loganthan et al., 2017; 2018; 2019; Szczerba et al., 2015; Wang et al., 2009), the postdoctoral researcher will also perform computational atomistic modeling to investigate the molecular mechanisms of gas sorption in clay-based materials with further extension to a mesoscale and multiscale modeling.
Technique involved: H2 sorption isotherms at low and high pressure, hydrothermal synthesis, XRD/SEM/TEM/BET/ATG-DTD mineralogical characterizations, neutron scattering and diffraction, and computational atomistic modeling.
It is a collaborative research program in-between ISTerre (Grenoble, France) and Subatech (Nantes, France) labs. The two research institutes will share their equipment, skills and knowledge to study H2 adsorption at the surface of clay minerals and clay assemblages present in a nuclear wastes geological repository hosted in clay-rocks.
This position is part of the European Joint Programme on Radioactive Waste Management (https://cordis.europa.eu/project/rcn/223662/factsheet/en), EURAD Project, financially supported by the European Commission (H2020).
General information about ISTerre and Subatech laboratories are available at: http://isterre.fr and http://www-subatech.in2p3.fr/fr/
The applicants should hold a PhD degree (or aquivalent) in Geology, Chemistry, Physics or Materials Science by October 2019.
We seek for a highly motivated person, particularly interested in materials chemistry and physics, phyllosilicates mineralogy, and enjoying laboratory experimental and analytical work. The candidate should, in addition, have a strong background in crystal chemistry.
Knowledge of French is not mandatory but the candidate must be proficient in English.
This posdoctoral fellowship is primarily subject to the applicant's education records and performance during the interview.
The candidates should submit a statement of research experience and interests, a detailed CV including the complete list of publications / abstracts / conferences, and the names and contact information of two potential referees.
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