2024 AIChE Annual Meeting
(308h) Dehydrogenation of per-Hydro Mono-Benzyl Toluene through Dual Doping of Phosphorus and Sulfur in Pt/Al2O3
Among hydrogen storage and transport methods, Liquid Organic Hydrogen Carriers (LOHCs) have gained attention as potential solutions. Monobenzyltoluene (MBT) has emerged as a candidate material due to its gravimetric hydrogen storage capacity of 6.22 wt% and feasibility for commercialization. However, the development of a stable catalyst for perhydro-MBT (H12-MBT) dehydrogenation has been a crucial challenge, particularly in maintaining activity and durability during the dehydrogenation process. This study demonstrates the dual doping effect of phosphorus and sulfur in facilitating the selective adsorption of sulfur species onto Pt during the dehydrogenation of H12-MBT. A catalyst, denoted as SPt/0.9PA, was developed to achieve this selective sulfur decoration onto Pt metal. Phosphate impregnated on the support geometrically blocks the adsorption site of sulfur. Additionally, the adsorption of sulfur is electronically further increased by transferring electrons to Pt. SPt/0.9PA exhibits a higher ratio of partially positively charged Pt atoms resulting from sulfur species doping, attributed to phosphate occupying alumina acidic sites and preventing sulfur from adsorbing onto high-energy sites of Al2O3. Thus, sulfur strongly interacts with Pt, forming cationic Pt and exhibiting higher stability compared to other catalysts. Moreover, Pt atoms also exhibit coke resistance. Ultimately, this catalytic development enhances the durability of the catalyst for hydrogen release from H12-MBT. This strategy of selectively adsorbing sulfur onto active metal presents a crucial design principle for heterogeneous catalysts.
