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The High‐Temperature Acidity Paradox of Oxidized Carbon: An in situ DRIFTS Study

Herold, Felix ; Oefner, Niklas ; Zakgeym, Dina ; Drochner, Alfons ; Qi, Wei ; Etzold, Bastian J. M. (2022)
The High‐Temperature Acidity Paradox of Oxidized Carbon: An in situ DRIFTS Study.
In: ChemCatChem, 2022, 14 (4)
doi: 10.26083/tuprints-00021534
Artikel, Zweitveröffentlichung, Verlagsversion

Kurzbeschreibung (Abstract)

Until now, oxygen functionalized carbon materials were not considered to exhibit significant acidity at high temperatures, since carboxylic acids, the most prominent acidic functionality, are prone to decarboxylation at temperatures exceeding 250 °C. Paradoxically, we could show that oxidized carbon materials can act as highly active high‐temperature solid acid catalysts in the dehydration of methanol at 300 °C, showing an attractive selectivity to dimethyl ether (DME) of up to 92 % at a conversion of 47 %. Building on a tailor‐made carbon model material, we developed a strategy to utilize in situ DRIFT spectroscopy for the analysis of carbon surface species under process conditions, which until now proofed to be highly challenging due to the high intrinsic absorbance of carbon. By correlating the catalytic behavior with a comprehensive in situ DRIFTS study and extensive post mortem analysis we could attribute the high‐temperature acidity of oxidized carbons to the interaction of thermally stable carboxylic anhydrides and lactones with nucleophilic constituents of the reaction atmosphere e. g. methanol and H₂O. Dynamic equilibria of surface oxides depending on reaction atmosphere and temperature were observed, and a methyl ester, formed by methanolysis of anhydrides and lactones, was identified as key intermediate for DME generation on oxidized carbon catalysts.

Typ des Eintrags: Artikel
Erschienen: 2022
Autor(en): Herold, Felix ; Oefner, Niklas ; Zakgeym, Dina ; Drochner, Alfons ; Qi, Wei ; Etzold, Bastian J. M.
Art des Eintrags: Zweitveröffentlichung
Titel: The High‐Temperature Acidity Paradox of Oxidized Carbon: An in situ DRIFTS Study
Sprache: Englisch
Publikationsjahr: 2022
Ort: Darmstadt
Publikationsdatum der Erstveröffentlichung: 2022
Verlag: Wiley-VCH
Titel der Zeitschrift, Zeitung oder Schriftenreihe: ChemCatChem
Jahrgang/Volume einer Zeitschrift: 14
(Heft-)Nummer: 4
Kollation: 12 Seiten
DOI: 10.26083/tuprints-00021534
URL / URN: https://tuprints.ulb.tu-darmstadt.de/21534
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Herkunft: Zweitveröffentlichung DeepGreen
Kurzbeschreibung (Abstract):

Until now, oxygen functionalized carbon materials were not considered to exhibit significant acidity at high temperatures, since carboxylic acids, the most prominent acidic functionality, are prone to decarboxylation at temperatures exceeding 250 °C. Paradoxically, we could show that oxidized carbon materials can act as highly active high‐temperature solid acid catalysts in the dehydration of methanol at 300 °C, showing an attractive selectivity to dimethyl ether (DME) of up to 92 % at a conversion of 47 %. Building on a tailor‐made carbon model material, we developed a strategy to utilize in situ DRIFT spectroscopy for the analysis of carbon surface species under process conditions, which until now proofed to be highly challenging due to the high intrinsic absorbance of carbon. By correlating the catalytic behavior with a comprehensive in situ DRIFTS study and extensive post mortem analysis we could attribute the high‐temperature acidity of oxidized carbons to the interaction of thermally stable carboxylic anhydrides and lactones with nucleophilic constituents of the reaction atmosphere e. g. methanol and H₂O. Dynamic equilibria of surface oxides depending on reaction atmosphere and temperature were observed, and a methyl ester, formed by methanolysis of anhydrides and lactones, was identified as key intermediate for DME generation on oxidized carbon catalysts.

Freie Schlagworte: acid/base catalysis, carbon materials, carbon surface chemistry, heterogeneous catalysis, in situ spectroscopy
Status: Verlagsversion
URN: urn:nbn:de:tuda-tuprints-215343
Sachgruppe der Dewey Dezimalklassifikatin (DDC): 500 Naturwissenschaften und Mathematik > 540 Chemie
Fachbereich(e)/-gebiet(e): 07 Fachbereich Chemie
07 Fachbereich Chemie > Ernst-Berl-Institut > Fachgebiet Technische Chemie
Hinterlegungsdatum: 01 Jul 2022 11:56
Letzte Änderung: 04 Jul 2022 05:20
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