Two-dimensional Mo2C: An efficient promoter for hydrogen storage and release from a liquid organic hydrogen carrier

Two-dimensional Mo2C (2D-Mo2C) is reported for the first time as an effective promoter of a Pt/Al2O3 catalyst for both the hydrogenation and dehydrogenation of the liquid organic hydrogen carrier (LOHC) pair, dibenzyltoluene (DBT) and perhydro-dibenzyltoluene (H18-DBT), respectively. Addition of 6.2 wt% 2D-Mo2C to a Pt/Al2O3 catalyst resulted in a significant increase in both the degree of hydrogenation and dehydrogenation compared to the unpromoted catalyst. An analysis of the initial (120 min) perhydro-DBT dehydrogenation kinetics in the temperature range of 270–330 °C, resulted in a reduction in apparent activation energy from 119.5 ± 3.8 kJ/mol for the Pt/Al2O3 catalyst to 110.4 ± 5.6 kJ/mol for the 6.2 wt% 2D-Mo2C/Pt/Al2O3 catalyst. The 6.2 wt% 2D-Mo2C/Pt/Al2O3 catalyst was also more stable than the unpromoted catalyst over several consecutive cycles of hydrogenation and dehydrogenation. Catalyst characterization showed that addition of 2D-Mo2C resulted in an increase in particle size and electron density of the Pt, which enhanced both the hydrogenation and dehydrogenation reactions, despite the fact that the 2D-Mo2C alone was inactive for both reactions.