Communication Dans Un Congrès Année : 2025

Efficient perhydrobenzyltoluene dehydrogenation on Pt/TiO2

Résumé

Background and motivation. Liquid Organic Hydrogen Carrier (LOHC) technology has emerged as a promising way to store and release hydrogen. Among the various LOHC candidates, the perhydrobenzyltoluene (H12BT)-benzyltoluene - (H0BT) couple (Figure 1a) attracts significant attention due to its optimal physical and ecotoxic properties and its competitive H2 gravimetric storage density (6.2 wt%) [1]. However, H12BT dehydrogenation still presents multiple challenges, particularly the H2 release rate and the formation of methylfluorene (MF), a side product responsible for catalyst deactivation [1]. Here, we present a comprehensive study on the TiO2 phase composition and on the structural and catalytic properties of Pt nanoparticles (NPs), showing that Pt/TiO2 can achieve higher activity and selectivity than with a Pt/Al2O3 commercial reference. Materials and methods. A range of TiO2 supports with different anatase/rutile ratio was used, including commercial samples (P25 and P90 (anatase-rutile mixtures, Evonik), TiO2-rutile (Merck), and G5 (anatase, Tronox)), and calcined P25 and P90 (600 -700°C). The supports were named Ax, where x represents the titania's percentage of the anatase phase. A commercial 0.4 wt% Pt/γ-Al2O3 catalyst, supplied by Heraeus, was also used. 0.5 wt.% Pt/Ax catalysts were synthesized via incipient wetness impregnation using Pt(NH3)4(NO3)2 precursor followed by calcination and reduction. Catalytic tests were performed in a glass semi-batch reactor connected to a GC-TCD under the following conditions: H12BT = 20 g, Pt/H12BT=0.009 mol%, T= 260 °C, t = 4 h. The initial H2 productivity (P) was calculated from the initial slope of the degree of dehydrogenation (DoD) of H12BT versus time. The catalyst acidity was measured by pyridine adsorption, and the Pt structural properties were studied by CO adsorption, followed by FTIR. Results and discussion. For all catalysts, the size of Pt NPs on TiO2 was between 1.0 -1.6 nm. The catalysts' performance depends on the nature of the support. In particular, the presence of rutile was found to be quite important for H2 productivity, with Pt/A0 attaining 2.2 g(H2)/g(Pt)/min vs. 0.5 g(H2)/g(Pt)/min for Pt/A100. Yet, even small amounts of rutile significantly improve H2 productivity as Pt/A86 attained 2.0 g(H2)/g(Pt)/min. For comparison, Pt/Al2O3 P was only 1.4 g(H2)/g(Pt)/min. The product distribution (H6BT/H0BT) is similar for all the catalysts at the same conversion. As for the selectivity, Pt/TiO2 leads to less methylfluorene (MF) side-product (Figure 1b) than Pt/Al2O3. For instance, at an H0BT yield of 11 % using Pt/Al2O3, the MF yield is 0.40 %, whereas with Pt/A0, only 0.09 % MF is formed. Anatase was also found to favor the formation of MF (figure 1b). The higher yield of xMF was related to the higher acidity of Al2O3 and anatase and the higher amount of Pt uncoordinated sites in Pt NPs (PtAl2O3 > PtA100-A20 > PtA0). Acknowledgments. The authors acknowledge the financial support of the Clean Hydrogen partnership for the project UnLOCHked (Grant Agreement: 101111964). References[1] Rüde, T.; Dürr, S.; Preuster, P.; Wolf, M.; Wasserscheid, P.; Sust. Energ. Fuel., 2022, 6, 1541–1553

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Dates et versions

hal-05234644 , version 1 (02-09-2025)

Identifiants

  • HAL Id : hal-05234644 , version 1

Citer

N. Marchenko, M. Kharma, F. Morfin, L. Piccolo, N. Batalha, et al.. Efficient perhydrobenzyltoluene dehydrogenation on Pt/TiO2. EuropaCat 2025, Aug 2025, Trondheim, Norway. ⟨hal-05234644⟩
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