Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Well-Defined Silanols in the Structure of the Calcined High-Silica Zeolite SSZ-70: New Understanding of a Successful Catalytic Material
Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Laboratory of Crystallography, Switzerland.ORCID iD: 0000-0002-5413-9038
Show others and affiliations
Number of Authors: 102017 (English)In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 139, no 46, p. 16803-16812Article in journal (Refereed) Published
Abstract [en]

The structure of the calcined form of the high-silica zeolite SSZ-70 has been elucidated by combining synchrotron X-ray powder diffraction (XRPD), high-resolution transmission electron microscopy (HRTEM), and two-dimensional (2D) dynamic nuclear polarization (DNP)-enhanced NMR techniques. The framework structure of SSZ-70 is a polytype of MWW and can be viewed as a disordered ABC-type stacking of MWW-layers. HRTEM and XRPD simulations show that the stacking sequence is almost random, with each layer being shifted by +/- 1/3 along the < 110 > direction with respect to the previous one. However, a small preponderance of ABAB stacking could be discerned. DNP-enhanced 2D Si-29{Si-29} J-mediated NMR analyses of calcined Si-SSZ-70 at natural Si-29 isotopic abundance (4.7%) establish the through-covalent-bond Si-29-O-Si-29 connectivities of distinct Si sites in the framework. The DNP-NMR results corroborate the presence of MWW layers and, more importantly, identify two distinct types of Q(3) silanol species at the surfaces of the interlayer regions. In the first, an isolated silanol group protrudes into the interlayer space pointing toward the pocket in the adjacent layer. In the second, the surrounding topology is the same, but the isolated -SiOH group is missing, leaving a nest of three Si-O-H groups in place of the three Si-O-Si linkages. The analyses clarify the structure of this complicated material, including features that do not exhibit long-range order. With these insights, the novel catalytic behavior of SSZ-70 can be better understood and opportunities for enhancement recognized.

Place, publisher, year, edition, pages
2017. Vol. 139, no 46, p. 16803-16812
National Category
Chemical Sciences
Identifiers
URN: urn:nbn:se:su:diva-150900DOI: 10.1021/jacs.7b08810ISI: 000416496400053PubMedID: 29068208OAI: oai:DiVA.org:su-150900DiVA, id: diva2:1171645
Available from: 2018-01-08 Created: 2018-01-08 Last updated: 2022-02-28Bibliographically approved

Open Access in DiVA

No full text in DiVA

Other links

Publisher's full textPubMed

Authority records

Smeets, StefWan, WeiZou, XiaodongChmelka, Bradley F.

Search in DiVA

By author/editor
Smeets, StefWan, WeiZou, XiaodongChmelka, Bradley F.
By organisation
Department of Materials and Environmental Chemistry (MMK)
In the same journal
Journal of the American Chemical Society
Chemical Sciences

Search outside of DiVA

GoogleGoogle Scholar

doi
pubmed
urn-nbn

Altmetric score

doi
pubmed
urn-nbn
Total: 28 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf