Synergistic Effectbetween Pt and CrO_<i>x</i> on Reversible Hydrogenationand Dehydrogenationof Dibenzyltoluene

Liquid organic hydrogen carriers are a safe and economic alternative for hydrogen storage and long-distance transport. A new dopant, CrO_<i>x</i>, was developed and added to Pt/Al₂O₃, and the obtained catalysts exhibited higher performance of perhydro dibenzyltoluene (H18-DBT) dehydrogenation with the increasing CrO_<i>x</i> amounts until 1 wt %. On the contrary, the performance of dibenzyltoluene (DBT) hydrogenation decreased with the increasing amount of CrO_<i>x</i>. The degree of dehydrogenation was dramatically improved to 87.2% after adding 1 wt % CrO_<i>x</i> compared to the unmodified Pt/Al₂O₃ catalyst (65.6%), and the hydrogenation activity was stable within ten cycles of reversible hydrogenation and dehydrogenation of DBT. With the increasing CrO_<i>x</i> amounts, CrO_<i>x</i> species aggregated to polychromates and then crystalline Cr₂O₃, leading to higher Pt electron density, smaller Pt particle size, and further, a higher dehydrogenation activity and lower hydrogenation performance. Polychromates were identified as important species for dehydrogenation.