CoMprehension & Optimization of high temperature CO2 Electrolysis in Carbonates – MCEC

It has become compulsory worldwide to reduce carbon fingerprint due to global warming. In addition to renewable energies which reduce CO2 emissions, sequestration and re-use of CO2 is a significant challenge and could represent a new energetic paradigm. Moreover, CO2 valorization could decelerate fossil energy dependence. Different routes can be considered but this project is focused on electrolysis as a clean and efficient way to transform CO2 in molten carbonates in which this molecule is highly soluble. It should also be added that molten carbonates are the electrolytes used in molten carbonate fuel cells (MCFCs), a mature technology at the edge of commercialization. This ANR proposal, MCEC (CoMprehension & Optimization of high temperature CO2 Electrolysis in Carbonates), fits within the scope of “a clean, safe and effective energy”. The target is to optimize high temperature CO2 electrolysis (550 to 800°C) into valuable fuels in molten carbonates, following a rigorous predictive/experimental methodology based on realistic conditions and assays in small electrolysis cells easy to scale-up further on at a pre-pilot level. This thematic on a very hot topic, which is beginning to stimulate interest in several countries and ambitious research programs (mainly in China, Japan, United-States,…), constitutes a unique innovative and integrated approach of CO2 valorization in molten salts, combining the use of high temperature NMR spectroscopy, physical chemistry of electrolyte media and electrochemistry with numerical modeling (First-principles molecular dynamics, FPMD, and Monte Carlo simulations based on first principle energy calculations, FPMC) for the characterization of molten alkali carbonates, including CO2 solvation, solubility and electrochemical reduction features. In particular, NMR will allow estimating the relative concentration of the complexes formed in the melt between carbon dioxide and carbonate ions as well as self-diffusion coefficients. Electrical conductivity and solubility measurements in molten carbonate media will be performed using original in situ approaches. Simulation and experimental tests will be focused on the speciation by means of anionic species description depending on CO2 solubility. These data will help us determining the complex electroreduction mechanism and selecting the most advantageous electrolysis physical and chemical conditions (pressure, temperature, CO2 partial pressure, nature and composition of the molten carbonate electrolyte). All these data will allow rationalizing and optimizing our main target, the CO2 electrolysis process (including co-electrolysis of water), from mechanistic to performance aspects. This proposal will be enriched through a global analysis of the application, simulating Balance of Plant, economic viability and comparison to other competitive technologies.
The growing challenge of CO2 valorization in molten carbonates requires an up-to-date, multidisciplinary program embracing a large panel of expertise. MCEC, precisely focused in such direction, is a collaborative Project gathering five research groups internationally recognized with specific high level competences in molten salts chemistry, modeling, electrochemistry, spectroscopic techniques and science of industrial processes up to economical viability. Moreover, this project is in tune with an Equipex program PLANEX “Experimental planet: in situ analysis in extreme conditions” (PLAnète EXpérimentale : Analyses in-situ en conditions extrêmes - ANR-11-EQPX-0036), with the participation of 3 of the 5 partners (IRCP, CEMHTI and ISTO).