Advanced bifunctional organometallic ruthenium catalysts for the sustainable conversion of bio-derived compounds into valuable products

My doctoral thesis focuses on the development and optimization of homogeneous catalytic systems for the upgrading of bio-based chemicals. In the first chapter, a mechanistic investigation into the role of benzoquinone in the ruthenium-catalysed Guerbet reaction is investigated. Experimental and DFT computational studies revealed that hydroquinone, the reduced form of the additive, acts as a proton source, significantly improving reaction kinetics. To further enhance efficiency, the application of microwave irradiation to the Ru-NHC catalysed Guerbet reaction was explored, resulting in drastic reductions in reaction time and base loading while maintaining high activity. Moving from the laboratory to process scale, a comprehensive Life Cycle Assessment (LCA) and scale-up simulation were performed. This analysis identified that utilizing waste biomass and integrated cogeneration units offers the most environmentally sustainable configuration for the industrial production of bio-butanol. The transition from batch to continuous processing was subsequently addressed during a secondment at Johnson Matthey, where the homogeneous catalytic system composed by a Ruthenium catalyst and NaOEt as base was tested in flow conditions to better assess its industrial viability. The methodology was successfully adapted for use in a Vapourtec continuous flow reactor. Further scale-up efforts focused on optimizing the Ru-NHC system by introducing Cs2CO3 as a basic co-catalyst, which eliminated acetate formation, and utilizing molecular sieves to achieve complete selectivity for alcohols. Expanding on the application of these products, the catalytic etherification of Guerbet alcohols was investigated using the acidic resin Amberlyst©15, providing a viable route for synthesizing heavier derivatives suitable for sustainable aviation fuels. Finally, the research addressed the valorization of 5-hydroxymethylfurfural (HMF): the hydrogenation to BHMF using Shvo’s complex was scaled up to the multigram scale (up to 6 g) in anisole, and the resulting product was successfully employed as a monomer for the synthesis of novel bio-based polycarbonates and polyesters.