Perhydrobenzyltoluene dehydrogenation using monometallic M/Al2O3 and bimetallic Pt-M/Al2O3 catalysts (M = Co, Ni): Effect of metal content.

Hydrogen production from renewable sources emerges as a key strategy for decarbonizing the energy system. However, the advancement of the hydrogen-based energy economy is delayed by limitations in storage and transportation systems. Over the past decade, H₂ chemical storage, particularly systems based on liquid organic hydrogen carriers (LOHCs), have emerged as a promising solution, employing reversible catalytic reactions for hydrogen storage within organic compounds [1-3].

Platinum-Group-Metal (PGM)-based catalysts have been identified as optimal for LOHC technology [4-7]. However, their high cost and environmental impact set significant barriers for large scale applications. To mitigate this challenge, we investigated the perhydrobenzyltoluene dehydrogenation process to benzyltoluene, focusing on minimizing PGM usage.

In this work, we synthesized bimetallic catalysts (Pt-M/Al₂O₃) with low Pt-content (0.5 wt.%) and varying second metal loads (M = Co, Ni). Catalysts were prepared using the incipient wetness impregnation method, wincorporating Co and Ni first, followed by a second impregnation of Pt, as described elsewhere [6]. Additionally, monometallic Co/Al₂O₃ and Ni/Al₂O₃ catalysts were prepared for comparison. Dehydrogenation tests were conducted in a laboratory-scale batch reactor, with hydrogen release quantified using a flow indicator (Brooks SLA5800).

The activity results, summarized in the following figure and attached as a dataset, reveal that monometallic Co/Al₂O₃ and Ni/Al₂O₃ exhibited poor dehydrogenation performance, with a Degree of Dehydrogenation (DoD) lower than 10%. Conversely, bimetallic catalysts, particularly those with reduced Ni and Co contents, demonstrated enhanced dehydrogenation activity, achieving optimal rates with a 0.5 wt.% metal load. Upon comparing the activity results, it was observed that Co exhibited greater activity than Ni when considering the same metal content. These findings highlight the superior dehydrogenation promotion capability of Co.

In summary, this study underscores the potential of low-metal content and sustainable catalysts as initial steps toward optimizing metal content for LOHC technology. These findings offer promising possibilities for enhancing the efficiency and sustainability of hydrogen storage and release systems, crucial for realizing the full potential of hydrogen as a clean energy carrier.