Critical Raw Materials, including Platinum-Group Metals, are key to enable Europe to meet its 2030 climate and strategic autonomy objectives. The ambition of the PARCOVAL project is to demonstrate the extraction of palladium from spent nuclear fuels and its use outside the nuclear industry. Moreover, the projects targets to address the challenge of CO2 valorisation, benefiting from palladium’s high catalytic power. Thus, PARCOVAL aims to create two circular loops from two wastes, Pd and CO2.
Concretely, PARCOVAL aims at extracting the radioactive Pd from spent nuclear fuel, today vitrified with nuclear wastes at the ORA Recycling Plant (La Hague) and demonstrating its use and valorisation as a catalyst for the green energy transition: alloyed with silver (Ag), recovered Pd will be used to break the CO2 molecule coming from an existing industry into CO through an electrocatalytic process, which is a key step to use the carbon atom further in green chemistry (e.g. monomer synthesis, e-fuel, etc.). Contrary to the other usual technologies (e.g. thermoconversion), electroconversion conditions are more compatible with radioactive security requirements.
Carbon dioxide can be sourced as a by-product of industrial anaerobic digestion. This will demonstrate the added value of the bio-sourced CH4 and support its development in Europe. The integration of the CO2 molecule in chemicals is difficult since it requires a reduction and a functionalisation step to be synchronised. PARCOVAL partners propose to use CO as a reactive intermediate, allowing to decouple the reduction step (CO2RR), from CO2 to CO, and the functionalisation, from CO to a high-value compound. Using CO as a reactive intermediate in carbonylation reactions provides an entry point to a larger class of high-value chemicals.
Among those, monomers such as cyclic anhydrides are especially interesting since they can be incorporated further in polyesters through copolymerisation. This allows for a mass substitution in a polymer: for a biodegradable polyester such as poly(ethylene succinate) (PES), with the PARCOVAL solution, up to 19.4 wt.% is coming from CO2 in the final product, instead of coming from fossil sources. PARCOVAL proposes to use CO for the carbonylation of acrylic acid, the latter expected to be produced from biomass in the coming years. The obtained succinic anhydride would allow a technological development towards bio-based polymers, where up to 69% of the mass of PES would be non-fossil (when the succinic anhydride comes from biomass-based acrylic acid and CO2-based CO).
PARCOVAL will demonstrate the incorporation of CO produced from CO2 electroreduction to produce a potentially bio-based monomer, the succinic anhydride. Moreover, PARCOVAL opens up the potentially positive impact of radioactivity in the catalyst performances.
Finally, upscaling is key to PARCOVAL, demonstrating radioactive Pd recovery up to the gram-scale, catalyst synthesis and electrocatalytic performance from 1 cm² to 100 cm² – including long-term experiments (100 h) –, and 10 g scale monomer synthesis from carbonylation reaction.
