Enhanced activity of a WO_x-incorporated Pt/Al₂O₃ catalyst for the dehydrogenation of homocyclic LOHCs: Effects of impregnation sequence on Pt–WO_x interactions

This study focused on the development of catalysts for the dehydrogenation of perhydro-dibenzyltoluene (H₁₈-DBT) and perhydro-benzyltoluene (H₁₂-BT), which are promising liquid organic hydrogen carriers (LOHCs). The reaction was performed at a low temperature to ensure hydrogen purity and catalyst durability, and the incorporation of WO_x into Pt/Al₂O₃ was investigated to improve the low-temperature activity of the Pt/Al₂O₃ catalyst. WO_x-incorporated Pt/Al₂O₃ catalysts with superior performance compared to that of the Pt/Al₂O₃ catalyst were developed by controlling the amount of incorporated WO_x and the impregnation sequence of metals during catalyst preparation. TEM, chemisorption, and XPS analyses assisted in confirming the changes in the structure and electron density of the active material in accordance with the impregnation sequence and the amount of incorporated WO_x; moreover, these factors were found to influence the catalyst performance. The electron-donating ability of W was determined according to the impregnation sequence of the metals, and confirmed by XPS analysis and the experimental reaction results. A DFT study on a hypothetical model containing WO_x confirmed the donation of electrons from W to Pt, which was consistent with the experimental results. In addition, the H₁₂-BT dehydrogenation on the investigated catalyst was kinetically more favorable compared to that on the Pt/Al₂O₃ catalyst, resulting in an enhancement of the dehydrogenation activity.