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/Alþinspace=þinspace0.20 and Si/Alþinspace=þinspace11 was subjected to three reaction cycles yielding ultimately 96 µmol\$\$\_\\\\backslashtext\C\\\\\backslashtext\H\\\_3\\\backslashtextØH\\\\/\\\backslashtext\g\\\_\\\backslashtext\zeolite\\\\\$\$CH3OH/gzeolite. Normalized to the Cu loading, this accounts for 0.33 mol\$\$\_\\\\backslashtext\C\\\\\backslashtext\H\\\_3\\\backslashtextØH\\\\\$\$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.
%0 Journal Article
%1 Pappas2019
%A Pappas, Dimitrios K.
%A Borfecchia, Elisa
%A Lomachenko, Kirill A.
%A Lazzarini, Andrea
%A Gutterød, Emil S.
%A Dyballa, Michael
%A Martini, Andrea
%A Berlier, Gloria
%A Bordiga, Silvia
%A Lamberti, Carlo
%A Arstad, Bjørnar
%A Olsbye, Unni
%A Beato, Pablo
%A Svelle, Stian
%D 2019
%J Topics in Catalysis
%K
%N 7
%P 712--723
%R 10.1007/s11244-019-01160-7
%T Cu-Exchanged Ferrierite Zeolite for the Direct CH4 to CH3OH Conversion: Insights on Cu Speciation from X-Ray Absorption Spectroscopy
%U https://doi.org/10.1007/s11244-019-01160-7
%V 62
%X 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/Alþinspace=þinspace0.20 and Si/Alþinspace=þinspace11 was subjected to three reaction cycles yielding ultimately 96 µmol\$\$\_\\\\backslashtext\C\\\\\backslashtext\H\\\_3\\\backslashtextØH\\\\/\\\backslashtext\g\\\_\\\backslashtext\zeolite\\\\\$\$CH3OH/gzeolite. Normalized to the Cu loading, this accounts for 0.33 mol\$\$\_\\\\backslashtext\C\\\\\backslashtext\H\\\_3\\\backslashtextØH\\\\\$\$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.
@article{Pappas2019,
abstract = {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{\thinspace}={\thinspace}0.20 and Si/Al{\thinspace}={\thinspace}11 was subjected to three reaction cycles yielding ultimately 96 {\textmu}mol{\$}{\$}{\_}{\{}{\{}{\{}{\backslash}text{\{}C{\}}{\}}{\{}{\{}{\backslash}text{\{}H{\}}{\}}{\_}3{\}}{\{}{\backslash}text{\{}OH{\}}{\}}{\}}{\}}/{\{}{\{}{\backslash}text{\{}g{\}}{\}}{\_}{\{}{\{}{\backslash}text{\{}zeolite{\}}{\}}{\}}{\}}{\$}{\$}CH3OH/gzeolite. Normalized to the Cu loading, this accounts for 0.33 mol{\$}{\$}{\_}{\{}{\{}{\{}{\backslash}text{\{}C{\}}{\}}{\{}{\{}{\backslash}text{\{}H{\}}{\}}{\_}3{\}}{\{}{\backslash}text{\{}OH{\}}{\}}{\}}{\}}{\$}{\$}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.},
added-at = {2020-05-15T11:51:55.000+0200},
author = {Pappas, Dimitrios K. and Borfecchia, Elisa and Lomachenko, Kirill A. and Lazzarini, Andrea and Gutter{\o}d, Emil S. and Dyballa, Michael and Martini, Andrea and Berlier, Gloria and Bordiga, Silvia and Lamberti, Carlo and Arstad, Bj{\o}rnar and Olsbye, Unni and Beato, Pablo and Svelle, Stian},
biburl = {https://puma.ub.uni-stuttgart.de/bibtex/20983dc357a1fd9d93dc53f1969c4e354/ingo},
day = 01,
doi = {10.1007/s11244-019-01160-7},
interhash = {cffde86f405f21b8ff5995d9d500be47},
intrahash = {0983dc357a1fd9d93dc53f1969c4e354},
issn = {1572-9028},
journal = {Topics in Catalysis},
keywords = {},
month = aug,
number = 7,
pages = {712--723},
timestamp = {2020-05-15T09:51:55.000+0200},
title = {Cu-Exchanged Ferrierite Zeolite for the Direct CH4 to CH3OH Conversion: Insights on Cu Speciation from X-Ray Absorption Spectroscopy},
url = {https://doi.org/10.1007/s11244-019-01160-7},
volume = 62,
year = 2019
}