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Cu-Exchanged Ferrierite Zeolite for the Direct CH4 to CH3OH Conversion: Insights on Cu Speciation from X-Ray Absorption Spectroscopy

Cu-Exchanged Ferrierite Zeolite for the Direct CH4 to CH3OH Conversion: Insights on Cu Speciation from X-Ray Absorption Spectroscopy

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Sammendrag
The direct stepwise transformation of CH4 to CH3OH over Cu-exchanged zeolites has been an intensively researched reaction as it can provide a solution for the utilization of this abundant feedstock. Up to date a commercial process is far from realization, which is why an understanding of the Cu speciation in zeolites as a function of reaction conditions as well as the development of a mechanistic view of the reaction are necessary to further advance the field. Herein we study Cu-exchanged ferrierite zeolite for the direct CH4 to CH3OH conversion by utilizing X-ray absorption spectroscopy (XAS), in order to assess the local structure and electronic properties of Cu through the reaction. A Cu-FER sample with a Cu/Al = 0.20 and Si/Al = 11 was subjected to three reaction cycles yielding ultimately 96 µmol CH3OH/gzeolite . Normalized to the Cu loading, this accounts for 0.33 mol CH3OH /molCu, making the sample comparable to very active Cu-MOR materials reported in the literature. During O2 activation, a transient self-reduction regime of CuII to CuI ions was identified; eventually leading to mostly framework interacting CuII species. CH4 loading leads to a reduction of these CuII containing species; which are finally partially reoxidized during H2O-assisted CH3OH extraction. The speciation after CH4 activation as well as H2O-assisted CH3OH extraction was assessed via linear combination fitting analysis of the XAS data.
Oppdragsgiver
  • Norges forskningsråd / 237922
Språk
Engelsk
Forfatter(e)
  • Pappas Dimitrios
  • Borfecchia Elisa
  • Lomachenko Kirill A.
  • Lazzarini Andrea
  • Gutterød Emil Sebastian
  • Dyballa Michael Martin
  • Martini Andrea
  • Berlier Gloria
  • Bordiga Silvia
  • Lamberti Carlo
  • Arstad Bjørnar
  • Olsbye Unni
  • Beato Pablo
  • Svelle Stian
Institusjon(er)
  • Universitetet i Oslo
  • Universitetet i Oslo
  • Haldor Topsoe A/S
  • Università degli Studi di Torino
  • European Synchrotron Radiation Facility
  • SINTEF Industri
  • Southern Federal University
  • SINTEF Industri / Prosessteknologi
År
2019
Publisert i
Topics in catalysis
ISSN
1022-5528
Årgang
62
Hefte nr.
7-11