Experimental study of the H2-CO2 system under hydrothermal conditions : geochemical and industrial implications for the abiotic synthesis of organic molecules

Titre : Experimental study of the H₂-CO₂ system under hydrothermal conditions : geochemical and industrial implications for the abiotic synthesis of organic molecules

Laboratoire de rattachement : ISTERRE (Minéralogie & Environnements)

Encadrant : Fabrice Brunet

Téléphone :+33 (0)4 76 51 41 06

Mots clés : CO2 hydrogenation, Energy, Hydrothermal experiments, Thermochemical modeling

Contexte et objectifs de la mission de stage :
This M2 project is part of an interdisciplinary program which investigates how natural processes can be a source of inspiration for the Energy Transition. Here we would like to focus on CO₂ hydrogenation/reduction reaction kinetics in the H₂-CO₂ system under hydrothermal conditions relevant to nature (e.g., hydrothermal vents). In particular, we would like to study the catalytic effect of mineral surfaces with respect to the kinetics of these reactions (mainly carboxylic acids, alcohols and hydrocarbons synthesis). The work will consist in running experiments in the H₂O-H₂-CO₂ +/- minerals to pressures up to a few kbars and temperatures from room temperature up to a few hundred degrees. Mineral products, gas and aqueous phases will be characterized with a set of analytical techniques (XRPD, SEM, TEM, nanoSIMS, µRaman, GC, GC-MS) and the results will be compared to thermodynamic modelling in order to identify the limiting step of the CO2 hydrogenation reactions. This overall protocol is now relatively well established with the partner laboratories (Milesi et al., 2005). The aim of this M2 project is two-fold. First, it should help defining geochemical signatures for abiotic organic molecules (in particular unconventional hydrocarbons) synthesized in nature in the CO2 – H2 system. Second, this study should provide a new insight into the role of mineral surfaces as CO2 hydrogenation/reduction catalysts in a range of hydrothermal conditions. Ultimately, this approach may lead to the definition of new catalysts for the industry (e.g., acid formic, methanol, alkane synthesis).

Prérequis :
This work will be carried out in tight collaboration with four laboratories with specific skills : geosciences (ISTerre - Grenoble & IPGP - Paris), catalysis (IC2MP – Poitiers) and analytical organic chemistry (Chimie et Biochimie Pharmacologiques et Toxicologiques, Paris V). The results obtained in this work will also be compared to gas-solution geochemical data from H₂-rich natural environments either from continental (coll. IFPEN) or oceanic (coll. IFREMER) settings.

Milesi, V., Guyot, F., Brunet, F., Richard, L., Recham, N., Benedetti, M., Dairou, J. and Prinzhofer, A. (2015) Formation of CO2, H2 and condensed carbon from siderite dissolution in the 200–300 °C range and at 50 MPa. Geochimica et Cosmochimica Acta. in press.