Sustainable hydrogen storage: Thermochemistry of amino-alcohols as seminal liquid organic hydrogen carriers

Amino-alcohols are considered for sustainable hydrogen storage systems based on catalytic peptide formation. Experimental and theoretical thermochemical studies of amino-alcohols have been performed, including vapour pressure measurements, combustion calorimetry, and quantum-chemical calculations. The standard molar enthalpies of vaporization of amino-alcohols were calculated from the temperature dependence of the vapour pressures measured by the transpiration method. Energies of combustion for six amino-alcohols were measured using the high-precision combustion calorimetry. The available in the literature primary data on vapour pressures, enthalpies of vaporization, and enthalpies of formation of amino-alcohols were collected and evaluated. The experimental standard molar gas-phase enthalpies of formation of amino-alcohols were derived from the evaluated results. The high-level G3B3, G3MP2, and G4 quantum-chemical methods were used to establish consistency of the experimental and theoretical results. The surprisingly low enthalpy of reaction of the reversible dehydrogenation of 2-amino-ethanol, calculated from the experimental data, makes this liquid organic hydrogen carrier system (LOHC) promising for further optimization and development.