Synthesis of innovative single-atom catalysts (SAC) for the hydrogenation and dehydrogenation of LOHC

Overview & Synopsis

Single-atom catalysts are a recent class of catalysts consisting in isolated metal centers anchored on a support through coordinating atoms (C, N, O, P, S…), playing an important role. SACs can be tuned [1], changing the metal center (noble metals, transition metals…), the coordinating atoms for the electronic effects (O, N, S, P, B…) and the supports (carbon-based, MXenes, oxides, sulphides…). Many advantages are attributed to SACs: low amount of metal content, up to 100% metal efficiency, high specific activity, etc. Another advantage is the versatility of these catalysts, in terms of synthesis and applications. Indeed, many precursors can be used to synthesize SACs. Since 2018, the SACs have attracted a lot of attention, and numerous applications have been tested, in thermal, electro- and photo-catalysis. My work consists on finding a catalyst able to do both the hydrogenation and dehydrogenation reaction for a Liquid Organic Hydrogen Carrier. A LOHC is a system composed of a hydrogen-rich molecule and a lean-hydrogen molecule, linked together by catalytic de-hydrogenation reactions. LOHC systems allow a safer storage and transportation of dihydrogen using less energy than current methods (LH2, H2 pressurized tanks) in the general context of the hydrogen economy. The first tests are done on the dehydrogenation of formic acid. A first series of Co-based catalyst have been synthesized from Metal-Organic Framework (MOF) compounds, and then pyrolyzed to obtain Co-N-C catalysts. Then, a second series with Fe has been tested as well as bimetallic catalysts. Other ways of synthesis have started to be explored such as poly-phtalocyanines and carbon nanotubes (CNT). These catalysts have been partially characterized and then tested on formic acid dehydrogenation in autoclave.