Tuning the dehydrogenation performance of dibenzyl toluene as liquid organic hydrogen carriers

Strategies to decrease the dehydrogenation enthalpy (Delta H-d) of dibenzyl toluene (DBT) were examined by density functional theory (DFT) modeling. The stronger electron-donating substituent showed higher hydrogen-releasing properties. The sequences of the dehy-drogenation process of perhydro-dibenzyl toluene (18H-DBT) and perhydro-lithium 3,5-dibenzyl phenolate (18H-DBT-OLi), which is the compound of modified DBT with the highest potential, were the same. The energy required to release hydrogen from 18H-DBT-OLi (11.514 kcal/mol) was smaller than that from 18H-DBT (12.574 kcal/mol). In the hydrogen-releasing process, the rate-determining steps for the dehydrogenation of 18H- DBT and 18H-DBT-OLi were the 12H-DBT -> 10H-DBT + H-2 and 12H-DBT-OLi -> 10H-DBTOLi + H-2 steps, respectively. Furthermore, the charge distribution of 18H-DBT and 18HDBT-OLi was also explored. (c) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.