Environmentally friendly recycling of fuel-cell membrane electrode assemblies by using ionic liquids
Résumé
The platinum nanoparticles used as catalyst in Proton Exchange Membrane Fuel Cells (PEMFCs) could represent around 46 % of the total price of the cells1 for a large scale production which is one of the limitation of their commercialization. The recycling of this platinum catalyst can then be the best alternative to limit the production cost of PEMFCs. Usual recovery routes for spent catalysts containing platinum are pyro-hydrometallurgical processes in which a calcination step is followed by aqua regia treatment, generating fumes and NOx emission, respectively. An electrochemical recovery route is proposed here, more environmentally friendly, performed in "soft" temperature conditions and without any gases emission. It consists in the coupling of electrochemical leaching of platinum in chloride-based ionic liquids (ILs), followed by its electrodeposition. The leaching of platinum was studied in pure ionic liquids and in ionic liquids melts, at different temperatures and chloride contents. By modulating the composition of the ionic liquid melts, it is further possible to leach and electrodeposit the platinum from fuel cell electrodes in a single cell process, under inert or ambient atmosphere.
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