Liquid organic hydrogen carriers (LOHCs) are promising materials for hydrogen storage due to their convenient and stable physical properties. Recent studies have focused on benzyltoluene for its favorable properties; however, its low efficiency in hydrogenation and dehydrogenation processes limits its applicability. Therefore, an approach to overcoming this challenge through catalysis is necessary. In this study, Pt/Al₂O₃ catalysts promoted with Nb (Pt–Nb) exhibited enhanced activity and selectivity in both hydrogenation and dehydrogenation of benzyltoluene (optimal at 5 wt % Nb). The selective blocking of hyperactive undercoordinated Pt sites by niobium oxide played a crucial role in enhancing the selectivity and stability. Additionally, the electron-withdrawing effect and increased occurrence of hydrogen spillover resulting from its acidic properties could modify the interaction with the hydrogen. Notably, the introduction of the niobium promoter seems to create additional adsorption sites for hydrogen, thereby enhancing the efficiency of LOHC molecules to bind on the Pt surface. It was discovered that the terrace sites of Pt catalysts could act as gathering points for reverse-spillover hydrogen during LOHC reactions. Therefore, when promoted with Nb, the active Pt terrace sites become capable of efficiently adsorbing LOHC molecules while simultaneously serving as sites for reaction with returning hydrogen. In summary, the addition of the niobium promoter elevates the efficiency of the platinum terrace, which serves as the active site, while suppressing the adverse effects of undercoordinated Pt sites. However, the growth of NbO_x with increasing Nb content blocks the active terrace Pt sites, underscoring the need for appropriate optimization processes.

中文翻译：

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揭示 Niobia 促进对 Pt/Al2O3 的影响，以增强苄基甲苯反应中的催化性能


液态有机氢载体 （LOHC） 因其方便和稳定的物理特性而成为很有前途的储氢材料。最近的研究集中在苄基甲苯的有利特性上;然而，它在加氢和脱氢过程中的低效率限制了其适用性。因此，需要一种通过催化来克服这一挑战的方法。在本研究中，用 Nb （Pt-Nb） 促进的 Pt/Al₂O₃ 催化剂在苄基甲苯的加氢和脱氢反应中均表现出增强的活性和选择性（最佳浓度为 5 wt % Nb）。氧化铌选择性阻断过度活跃的配位不良 Pt 位点在增强选择性和稳定性方面起着至关重要的作用。此外，由于其酸性特性导致的吸电子效应和氢溢出发生率的增加可能会改变与氢的相互作用。值得注意的是，铌促进剂的引入似乎为氢创造了额外的吸附位点，从而提高了 LOHC 分子在 Pt 表面结合的效率。研究发现，Pt 催化剂的阶台位点可以作为 LOHC 反应过程中逆溢出氢的聚集点。因此，当用 Nb 促进时，活性 Pt 露台位点变得能够有效地吸附 LOHC 分子，同时作为与返回的氢反应的位点。总之，铌促进剂的加入提高了铂平台的效率，铂平台作为活性位点，同时抑制了配位不足的 Pt 位点的不利影响。 然而，NbO_x 随着 Nb 含量的增加而生长，阻断了活性阶地 Pt 位点，强调了适当优化过程的必要性。