Pt–Re dehydrogenation catalysts synthesized via solvent deficient precipitation

Abstract

This study demonstrates the feasibility of producing Pt–Re/Al₂O₃ catalysts via the scalable solvent deficient precipitation method achieving enhanced performance in the dehydrogenation of liquid organic hydrogen carriers. Effects similar to wet impregnated Pt–Re catalysts were observed, indicating the transferability of the Re promotion concept across catalyst synthesis approaches. In continuous gas-phase dehydrogenation of methyl cyclohexane, Re addition improved the Pt-based activity, selectivity, and stability, while reducing coking and effective activation energy. For perhydro benzyltoluene dehydrogenation, Re increased catalyst activity across various loadings with a molar ratio of Re/Pt = 0.5 yielding the highest hydrogen production rate. Higher Re loadings led to a rapid performance decline due to side reactions and catalyst deactivation, likely caused by deep dehydrogenation pathways and strong binding of the dehydrogenated product benzyltoluene to the active sites. Kinetic studies revealed that Re reduces the effective activation energy, although diffusional limitations were observed due to the small pore sizes of the produced catalyst materials. Successful 10-fold scale-up of the solvent-deficient precipitation was achieved without water, binders, or additives with performances comparable to small-scale syntheses. This highlights the potential of this simple, cost-effective, and scalable approach for the high-throughput production of bimetallic Pt-based catalysts.