Size and Structure Effects Controlling the Stability of the Liquid Organic Hydrogen Carrier Dodecahydro-N-ethylcarbazole during Dehydrogenation over Pt Model Catalysts

作者：Amende Max; Gleichweit Christoph; Schernich Stefan; Hoefert Oliver; Lorenz Michael P A; Zhao Wei; Koch Marcus; Obesser Katharina; Papp Christian; Wasserscheid Peter; Steinrueck Hans Peter; Libuda Joerg^*

来源：Journal of Physical Chemistry Letters, 2014, 5(8): 1498-1504.

DOI：10.1021/jz500157r

Hydrogen can be stored conveniently using so-called liquid organic hydrogen carriers (LOHCs), for example, N-ethylcarbazole (NEC), which can be reversibly hydrogenated to dodecahydro-N-ethylcarbazole (H-12-NEC). In this study, we focus on the dealkylation of H-12-NEC, an undesired side reaction, which competes with dehydrogenation. The structural sensivity of dealkylation was studied by high-resolution X-ray photoelectron spectroscopy (HR-XPS) on Al2O3-supported Pt model catalysts and Pt(111) single crystals. We show that the morphology of the Pt deposit strongly influences LOHC degradation via C-N bond breakage. On smaller, defect-rich Pt particles, the onset of dealkylation is shifted by 90 K to lower temperatures as compared to large, well-shaped particles and well-ordered Pt(111). We attribute these effects to a reduced activation barrier for C-N bond breakage at low-coordinated Pt sites, which are abundant on small Pt aggregates but are rare on large particles and single crystal surfaces.

• 出版日期2014-4-17