A study on hydrogen uptake and release of a eutectic mixture of biphenyl and diphenyl ether

Hydrogen storage in Liquid Organic Hydrogen Carrier (LOHC) systems is appealing for the safe storage and distribution of excess renewable energy via existing gasoline infrastructures to end-users. We present the eutectic mixture of biphenyl and diphenyl ether of its first use as a LOHC material. The material is hydrogenated with 99% selectivity without the cleavage of C–O bond, with commercial heterogeneous catalysts, which is confirmed by nuclear magnetic spectroscopy and gas chromatography-mass spectrometry. Equilibrium concentration, dehydrogenation enthalpy, and thermo-neutral temperature are calculated using a density functional theory. The results indicate that O-atom-containing material exhibits more favorable dehydrogenation thermodynamics than that of the hydrocarbon analogue. The H₂-rich material contains 6.8 wt% of gravimetric hydrogen storage capacity. A preliminary study of catalytic dehydrogenation on a continuous reactor is presented to demonstrate a reversibility of this material.