Speciation and coordination of Ru catalysts in hydrogenation and upcycling of end-of-life polybutadiene

This proposal aims to unravel the structure-activity relationships of catalytic Ru species during the selective hydrogenation and upcycling of end-of-life poly(butadiene) (PBD), an environmentally crucial recycling process. Intuitive optimization allowed us to obtain a homogeneous system yielding promising hydrogenation selectivities with adequate catalyst stability. The overall selectivity is mainly influenced by the applied hydrogen pressure and local environment of the Ru catalyst. However, no clear proof has been found yet of the exact nature of the active catalyst and as to why certain catalytic precursors clearly outperform others. To date, very little is known on the exact speciation and coordination environment of these in situ formed Ru catalysts. The main scientific questions that should thus be answered are: (i) what is the nature of the Ru catalyst?; (ii) which Ru species are active?; and (iii) what is the overall reaction mechanism to explain the selective hydrogenation?