Electrification of Selective Catalytic Liquid Organic Hydrogen Carriers: Hydrogenation and Dehydrogenation Reactions

The development of efficient, chemical hydrogen-storage materials is one of the greatest technical challenges for the coming hydrogen-based economy. Analyzed liquid organic hydrogen carriers (LOHCs), which bond, store, and release the H2 molecules through catalytic hydrogenation, cracking, and dehydrogenation cycles, are being considered as an alternative, functional option. The search for a highly industrialized reactive production process, coupled with the use of renewable electrical energy, has encouraged the consideration of characteristic stand-alone methods (such as microwave-assisted surface reactions, an increase in the rates by magnetic heating systems, electrocatalysis, variable photochemical manufacturing, and plasma). This mini review aims to highlight, assess, and critically evaluate these recent advances in the electrification of LOHC-related plant technologies. Besides base storing vectors, such as methanol, formaldehyde, and formic acid derivatives, reversible cycling compounds, i.e., benzene, toluene, polycyclic dibenzyl toluene (DBT), carbazole, and indole, are given an overview. These all compete with, for example, ammonia. Specific design methodologies, such as density functional theory (DFT), kinetics, mass-transfer phenomena, etc., are discussed, whether these were studied or the subject of modeling. Lastly, quantitative structure–performance relationships are correlated for activity, selectivity, and stability, where the latter was possible.