Hydrogen Production Based on Liquid Organic Hydrogen Carriers through Sulfur Doped Platinum Catalysts Supported on TiO₂

In order to move from a carbon-based energy system to a more sustainable one, focus is put on liquid organic hydrogen carrier (LOHC) systems for CO₂-free hydrogen storage and release. In this study sulfur as a dopant for the Pt/TiO₂ catalyst was identified to be a selective poison resulting in high performing catalysts in the dehydrogenation experiments with the LOHC system perhydro dibenzyltoluene/dibenzyltoluene (H18-DBT/H0-DBT). The Pt/TiO₂ and S–Pt/TiO₂ catalysts were compared to the current benchmarks Pt/γ-Al₂O₃ and S–Pt/γ-Al₂O₃. S–Pt/TiO₂ was found to achieve a high degree of dehydrogenation of 98% which is competitive to the benchmark S–Pt/γ-Al₂O₃. In addition, analyses of the side products resulted in a higher selectivity toward dibenzyltoluene for S–Pt/TiO₂ than for the γ-Al₂O₃ supported catalysts. Characterization with infrared spectroscopy (IR), transmission electron microscopy (TEM), and diffuse reflectance infrared Fourier transform spectroscopy with CO as adsorbing molecule (CO–DRIFTS) suggest the presence of strongly chemisorbed sulfur species as well as SMSI effects of the Pt/TiO₂ catalysts. Based on kinetic studies, a batch and plug flow reactor for the dehydrogenation reaction were simulated for both titania supported catalysts. According to the calculations, the sulfur doped catalyst displays higher conversions in both batch and plug flow operation as compared to the unmodified system Pt/TiO₂.