Synergistic Strategy for the Fast Dehydrogenation of Liquid Organic Hydrogen Carriers over a Pd/MoO₃ Catalyst

We report a synergistic strategy for the dehydrogenation of liquid organic hydrogen carriers (LOHCs) over a Pd/MoO3 catalyst. The effects of Pd loading, temperature, and the variation of HxMoO3 for the catalytic dehydrogenation behavior of LOHCs were investigated systematically. 5 wt % Pd/MoO3 shows the highest catalytic performance. 3.13 wt % release of the stored H2 of perhydro-N-ethylcarbazole (PNEC) was achieved in the initial 5 min, and full dehydrogenation was realized in 1.5 h at 200 °C. The kinetic results suggest that the turn-over frequency (TOF) of PNEC on the 5 wt % Pd/MoO3 catalyst is 191.11 min–1 at 180 °C, which is significantly larger than that of traditional noble metal catalyst 5 wt % Pd/Al2O3 (56.31 min–1). The dehydrogenation mechanism on Pd/MoO3 essentially differs from the traditional noble metal catalysts. The formation of HxMoO3 other than H2 greatly decreases the activation energy barrier of the dehydrogenation reaction and results in the swift desorption of H atoms from PNEC. The results indicate that the synergistic effect between Pd and MoO3 may be an efficient strategy for the fast dehydrogenation of LOHCs.