Reversible hydrogen storage with aromatics: boosting LOHC effectiveness through oxygen functionality

Abstract Liquid organic hydrogen carriers (LOHCs) represent a promising class of materials for reversible hydrogen storage and release, particularly when derived from renewable feedstocks such as lignin. Indane and indanone structures can form during lignin valorisation, especially under hydrogenolytic or pyrolytic conditions. Lignin-based compounds inherently contain oxygenated functional groups (e.g., carbonyl, methoxy, methyl, etc. substituents) that can influence the thermodynamics of hydrogenation and dehydrogenation reactions, thereby affecting overall storage efficiency. This study investigates the impact of oxygen functionalization in aromatic indane based systems on the thermodynamic parameters governing reversible hydrogenation. Reaction enthalpies, entropies, Gibbs free energies, and equilibrium temperatures were determined through a combination of experimental and empirical thermochemical data and high-level quantum chemical calculations. The results reveal that oxygen-substituted indane derivatives exhibit markedly lower reaction enthalpies and equilibrium temperatures compared to their unsubstituted aromatic counterparts. Overall, the results demonstrate that efficient hydrogen release from oxygen-functionalized aromatic molecules is thermodynamically feasible at temperatures well below 500 K - an essential criterion for practical LOHC operation. Graphical abstract Liquid organic hydrogen carriers (LOHCs) derived from lignin offer promising hydrogen storage. This study evaluates how oxygen functional groups affect hydrogenation thermodynamics of indane-based compounds. Quantum chemical and thermochemical analyses show reduced reaction enthalpies and equilibrium temperatures, enabling efficient hydrogen release below 500 K for practical LOHC applications