PNNL

Abstract

Storing hydrogen reversibly in the mass-produced cycloalkane and arene pairs provides a solution to the large-scale energy storage and long-distance hydrogen transportation. Herein, a novel alkali modification strategy for the thermodynamic optimization of cycloalkane-arene pairs is proposed and demonstrated. Our calculations and thermodynamic measurements show that the Na modified phenol-cyclohexanol pair has a dehydrogenation enthalpy change of 52 kJ mol-1 H2 which is significantly reduced by ca. 16 kJ mol-1 H2 from that of the pristine pair. 3 equivalents of H2 can be reversibly stored in the sodium modified phenol-cyclohexanol pair in aqueous solution, where the hydrogenation can take place at ambient temperature and 2 bar hydrogen pressure in the presence of commercial catalysts and, more importantly, dehydrogenation can be accomplished with >99% selectivity to H2 at 100°C.