Gleichweit Christoph, Amende Max, Bauer Udo, Schernich Stefan, Höfert Oliver, Lorenz Michael P A, Zhao Wei, Müller Michael, Koch Marcus, Bachmann Philipp, Wasserscheid Peter, Libuda Jörg, Steinrück Hans-Peter, Papp Christian
Lehrstuhl für Physikalische Chemie II, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstrasse 3, 91058 Erlangen, Germany.
Lehrstuhl für Chemische Reaktionstechnik, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstrasse 3, 91058 Erlangen, Germany.
J Chem Phys. 2014 May 28;140(20):204711. doi: 10.1063/1.4875921.
The concept of liquid organic hydrogen carriers (LOHC) holds the potential for large scale chemical storage of hydrogen at ambient conditions. Herein, we compare the dehydrogenation and decomposition of three alkylated carbazole-based LOHCs, dodecahydro-N-ethylcarbazole (H12-NEC), dodecahydro-N-propylcarbazole (H12-NPC), and dodecahydro-N-butylcarbazole (H12-NBC), on Pt(111) and on Al2O3-supported Pt nanoparticles. We follow the thermal evolution of these systems quantitatively by in situ high-resolution X-ray photoelectron spectroscopy. We show that on Pt(111) the relevant reaction steps are not affected by the different alkyl substituents: for all LOHCs, stepwise dehydrogenation to NEC, NPC, and NBC is followed by cleavage of the C-N bond of the alkyl chain starting at 380-390 K. On Pt/Al2O3, we discern dealkylation on defect sites already at 350 K, and on ordered, (111)-like facets at 390 K. The dealkylation process at the defects is most pronounced for NEC and least pronounced for NBC.
液态有机氢载体（LOHC）的概念为在环境条件下大规模化学储氢提供了潜力。在此，我们比较了三种基于烷基咔唑的LOHC，即十二氢 - N - 乙基咔唑（H12 - NEC）、十二氢 - N - 丙基咔唑（H12 - NPC）和十二氢 - N - 丁基咔唑（H12 - NBC）在Pt(111)以及氧化铝负载的Pt纳米颗粒上的脱氢和分解情况。我们通过原位高分辨率X射线光电子能谱对这些体系的热演化进行定量跟踪。我们表明，在Pt(111)上，相关反应步骤不受不同烷基取代基的影响：对于所有的LOHC，从380 - 390 K开始，逐步脱氢生成NEC、NPC和NBC，随后烷基链的C - N键断裂。在Pt/Al₂O₃上，我们发现在350 K时缺陷位点就已发生脱烷基化，在390 K时有序的（111）样晶面上也发生脱烷基化。缺陷处的脱烷基化过程对于NEC最为显著，对于NBC最不显著。
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