Key points are not available for this paper at this time.
High Resolution Image Download MS PowerPoint Slide Liquid organic hydrogen carriers (LOHC) are compounds that enable chemical energy storage through reversible hydrogenation. They are considered a promising technology to decouple energy production and consumption by combining high-energy densities with easy handling. A prominent LOHC is N -ethylcarbazole (NEC), which is reversibly hydrogenated to dodecahydro- N -ethylcarbazole (H 12 -NEC). We studied the reaction of H 12 -NEC on Pt(111) under ultrahigh vacuum (UHV) conditions by applying infrared reflection–absorption spectroscopy, synchrotron radiation-based high resolution X-ray photoelectron spectroscopy, and temperature-programmed molecular beam methods. We show that molecular adsorption of H 12 -NEC on Pt(111) occurs at temperatures between 173 and 223 K, followed by initial C–H bond activation in direct proximity to the N atom. As the first stable dehydrogenation product, we identify octahydro- N -ethylcarbazole (H 8 -NEC). Dehydrogenation to H 8 -NEC occurs slowly between 223 and 273 K and much faster above 273 K. Stepwise dehydrogenation to NEC proceeds while heating to 380 K. An undesired side reaction, C–N bond scission, was observed above 390 K. H 8 -NEC and H 8 -carbazole are the dominant products desorbing from the surface. Desorption occurs at higher temperatures than H 8 -NEC formation. We show that desorption and dehydrogenation activity are directly linked to the number of adsorption sites being blocked by reaction intermediates.
Amende et al. (Thu,) studied this question.