Evaluation of hydrogen donation ability of real hydrogen storage solvents by radical precursors

Hydrogen storage solvents (HSs) have drawn worldwide attention for viable transportation and utilization of hydrogen. The industrial HSs are mostly mixtures of countless compounds and have been used directly in hydrogenation reactions for decades, such as in the direct coal liquefaction. A good HS is of high hydrogen donation capacity, QH, and a low initial hydrogen donation temperature, Ti. These parameters have been quantified for some model HSs but not for real HSs. This work evaluates QH and Ti of 4 real HSs with two radical precursors and a first order kinetics, and correlates these parameters with molecular structures of the HSs. It is found that the maximum QH of real HSs is in the range of 20.8–36.3 mmol/g, which are higher than some model HS, such as dihydrophenanthrene (DHP) and dihydroanthracene (DHA), and one of them is even higher than that of tetralin (THN). The Ti of real HSs is in the range of 224.8–263.3 °C, which are similar to or slightly higher than those of DHP and DHA. The order of these parameters is found to be consistent with some of the HSs’ structure parameters, such as those characterized by GC × GC − MS, 13C NMR and 1H NMR.