(768e) Hydrogen Production from Iron Corrosion in CO2/H2O High Pressure Media

The reduction of anthropogenic CO₂ in the atmosphere is a critical challenge that needs to be adressed. The various strategies of CCUS (Carbon Capture Utilization and Storage) go in this direction and should allow to store and to valorize a non negligible part of the CO₂ emissions. In this context, deep underground storage coupled to an in situ valorization of CO₂ appears as a promising option. To do so, the goal would be to use the “unseen majority” of microorganisms living deep underground, among which are the methanogens Archaea, which are able to produce biogenic methane from the biochemical combinaison of hydrogen and CO₂ in geological conditions. To achieve this conversion, hydrogen is an essential element. Although natural hydrogen can be found in geological environments, its proportion is too small to consider an efficient transformation process, given the large amount of foreseen injected CO₂.

An interesting way to generate artificially hydrogen proceeds through the corrosion of iron in CO2 / Water media, as: Fe + CO₂ + H₂O ==> H₂ + FeCO₃.

To investigate this reaction, we have designed and used sapphire batch reactor operating under controlled conditions (20-150°C and 60-200 bar). Several operating parameters (CO₂ partial pressure, total pressure, reaction time, temperature, iron powder grain size ...) have been investigated to classify their effect on the overall hydrogen production. The kinetics data for H₂ production have been obtained by the analysis of the gas phase by micro-GC (gaz chromatography), while the solid phase formed during the (iron carbonate) was monitored using XRD (X-ray diffraction), SEM (Scanning electron microscopy) and TEM (transmission electron microscopy) analysis.

From these preliminary experiments, we have then switched to a fully continuous process by considering microfluidics segmented flows. This has provided a better control of the residence time, while allowing getting insights in the mechanisms thanks to the implementation of in situ characterization techniques. Eventually, we will highlight some recents results concerning the investigation of this hydrogen production reaction in model porous media (geological lab on chips) in order to get closer to the real geometry conditions. This last point is of particular interest in view of the final applications since we have studied the transport of particles in a porous media, and determined the distribution of reagents and products.