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Zeolite surface methoxy groups as key intermediates in the stepwise conversion of methane to methanol

Zeolite surface methoxy groups as key intermediates in the stepwise conversion of methane to methanol

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Sammendrag
This contribution clarifies the overoxidation-preventing key step in the methane-to-methanol (MTM) conversion over copper mordenite zeolites. We followed the methane-to-methanol conversion over copper mordenite zeolites by NMR spectroscopy supported by DRIFTS to show that surface methoxy groups (SMGs) located at zeolite Brønsted sites are the key intermediates. The SMGs with chemical shift of 59 ppm are identical to those formed on a copper-free reference zeolite after reaction with methanol and react with water, methanol, or carbon monoxide to yield methanol, dimethyl ether, and acetate. This reactivity corroborates the location of SMGs at Brønsted sites. We find no evidence for stable SMGs directly at copper sites and explain mechanistically why H-form mordenites outperform their Na-form analogues. This finding is of interest for any future process that tries to trap the intermediate methane oxidation product towards methanol.
Oppdragsgiver
  • Norges forskningsråd / 237922
Språk
Engelsk
Forfatter(e)
  • Dyballa Michael Martin
  • Thorshaug Knut
  • Pappas Dimitrios
  • Borfecchia Elisa
  • Kvande Karoline
  • Bordiga Silvia
  • Berlier Gloria
  • Lazzarini Andrea
  • Olsbye Unni
  • Beato Pablo
  • Svelle Stian
  • Arstad Bjørnar
Institusjon(er)
  • SINTEF Industri / Materialer og nanoteknologi
  • Universitetet i Oslo
  • Universitetet i Oslo
  • Università degli Studi di Torino
  • Haldor Topsoe A/S
  • SINTEF Industri / Prosessteknologi
År
2019
Publisert i
ChemCatChem
ISSN
1867-3880
Forlag
Wiley - VCH Verlag GmbH
Årgang
11
Hefte nr.
20
Side(r)
5022 - 5026