In this PhD dissertation, I explore new and unprecedented reactivity pathways based on the interaction between homogeneous catalysts and ionic liquids. The topics discussed in the thesis are highly attractive from a societal point of view, varying from hydrogen economy, carbon capture and utilization (CCU), hydrogen technologies for transportation, as well as renewable energy storage.
I will demonstrate that a suitable combination of a transition metal catalyst and ionic liquid is a powerful tool for relevant processes within sustainable chemistry and catalysis, namely hydrogenation and dehydrogenation reactions. The main novelty behind my project is represented by the use of ionic liquids as the only reaction additive. They act as solvent and catalyst activator without the use of e.g. inorganic bases and organic solvents, therefore avoiding formation of waste and increasing the atom efficiency of the process. In addition, ionic liquids stabilize the catalyst under operative conditions, resulting in extraordinary stability of the mixture under extended reaction times (months).
I detail, the so-obtained system is able to transform CO2 to the hydrogen carrier formic acid already at ambient conditions (1 bar, 25 ⁰C). The same catalytic system is also highly efficient for the reverse hydrogen release from formic acid; in fact, the results obtained in this work represent the new state-of-the art for this transformation at temperatures compatible with automotive fuel cell applications. Later, I will demonstrate the efficient hydrogen release from isopropanol, as well as the immobilization of the developed catalytic system on a support material using the Supported Ionic Liquid Phase (SILP) technology. As such, the SILP catalyst showed promising activity in continuous flow reaction conditions, usually inaccessible for the homogenous catalysts used in this study.
The research topics presented in this thesis are highly innovative and interesting subjects for both business and society. This interest has been acknowledged by the Hartmann foundation, as well as from the DTU Discovery Grant, from which I obtained DKK 85.000 and DKK 110.000 respectively, which were used for the purchase of relevant lab equipment. In addition, we have started a patenting process covering both the materials as well as the processes discussed in this thesis.