Characteristics of La-doped Pt/Al_2O_3 catalyst prepared by solvent-deficient method and effect on enhancement of dehydrogenation of perhydrodibenzyltoluene

摘要

Liquid organic hydrogen carrier (LOHC) materials have been under the spotlight for the storage, transport and extraction of hydrogen. In particular, the catalytic process for extracting hydrogen from LOHC requires a fairly high level of catalytic technology due to several important issues, such as saving energy consumption due to endothermic reaction, minimizing consumption of LOHC for recycle, and high purity of hydrogen produced. This study focused on the development of La-doped Pt/Al_2O_3 catalyst with high activity for the dehydrogenation of perhydrodibenzyltoluene (H_(18)-DBT), which is well-known as a LOHC compound. The dehydrogenation performance of the La-doped Pt/Al_2O_3 catalyst was different depending on the La content it contained. A variety of characterization techniques are used to identify the performance differences of the catalysts. As revealed by the analyses of chemisorption, TEM and XPS, the number of lanthanum oxide particles on the surface of the catalyst increases and block the active sites of platinum, as the amount of La doped in the catalyst increases. However, by donating electrons from lanthanum oxide to platinum, the activity per unit active site of Pt increases. The Pt/La-Al_2O_3 catalyst doped with 1 wt% La showed much higher activity than that of the Pt/Al_2O_3, and showed the best performance among the catalysts doped with various amounts of La. In addition, it was found through spin-lattice relaxation analysis that La doping by solution-deficient method did not have a positive effect on the Pt dispersion by creating Al_(penta)~(3+) sites inside the alumina particle rather than on the surface.