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Model Catalytic Studies of Novel Liquid Organic Hydrogen Carriers: Indole, Indoline and Octahydroindole on Pt(111)
Author(s) -
Schwarz Matthias,
Bachmann Philipp,
Silva Thais Nascimento,
Mohr Susanne,
Scheuermeyer Marlene,
Späth Florian,
Bauer Udo,
Düll Fabian,
Steinhauer Johann,
Hohner Chantal,
Döpper Tibor,
Noei Heshmat,
Stierle Andreas,
Papp Christian,
Steinrück H.P.,
Wasserscheid Peter,
Görling Andreas,
Libuda Jörg
Publication year - 2017
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201702333
Subject(s) - indoline , dehydrogenation , indole test , desorption , photochemistry , x ray photoelectron spectroscopy , chemistry , monolayer , catalysis , adsorption , materials science , crystallography , stereochemistry , organic chemistry , chemical engineering , biochemistry , engineering
Indole derivatives were recently proposed as potential liquid organic hydrogen carriers (LOHC) for storage of renewable energies. In this work, we have investigated the adsorption, dehydrogenation and degradation mechanisms in the indole/indoline/octahydroindole system on Pt(111). We have combined infrared reflection absorption spectroscopy (IRAS), X‐ray photoelectron spectroscopy (XPS) and DFT calculations. Indole multilayers show a crystallization transition at 200 K, in which the molecules adopt a strongly tilted orientation, before the multilayer desorbs at 220 K. For indoline, a less pronounced restructuring transition occurs at 150 K and multilayer desorption is observed at 200 K. Octahydroindole multilayers desorb already at 185 K, without any indication for restructuring. Adsorbed monolayers of all three compounds are stable up to room temperature and undergo deprotonation at the NH bond above 300 K. For indoline, the reaction is followed by partial dehydrogenation at the 5‐membered ring, leading to the formation of a flat‐lying di‐σ‐indolide in the temperature range from 330–390 K. Noteworthy, the same surface intermediate is formed from indole. In contrast, the reaction of octahydroindole with Pt(111) leads to the formation of a different intermediate, which originates from partial dehydrogenation of the 6‐membered ring. Above 390 K, all three compounds again form the same strongly dehydrogenated and partially decomposed surface species.