An Investigation of Molecular Templating in Amorphous Silicas by Cross-Polarization NMR Spectroscopy Metadata

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Title

  • Main Title An Investigation of Molecular Templating in Amorphous Silicas by Cross-Polarization NMR Spectroscopy

Creator

  • Author: Assink, R. A.
    Creator Type: Personal
  • Author: Brinker, C. J.
    Creator Type: Personal
  • Author: Click, C. A.
    Creator Type: Personal
  • Author: Naik, S. J.
    Creator Type: Personal

Contributor

  • Sponsor: United States. Department of Energy.
    Contributor Type: Organization
    Contributor Info: US Department of Energy (United States)

Publisher

  • Name: Sandia National Laboratories
    Place of Publication: Albuquerque, New Mexico
    Additional Info: Sandia National Labs., Albuquerque, NM, and Livermore, CA (United States)

Date

  • Creation: 1999-07-12

Language

  • English

Description

  • Content Description: The precise pore sizes defined by crystalline zeolite lattices have led to intensive research on zeolite membranes. Unfortunately zeolites have proven to be extremely difficult to prepare in a defect-free thin film form needed for membrane flux and selectivity. We introduce tetrapropylammonium (TPA), a structure-directing agent for zeolite ZSM-5, into a silica sol and exploit the development of high solvation stresses to create templated amorphous silicas with pore apertures comparable in size to those of ZSM-5. Silicon and carbon NMR experiments were performed to evaluate the efficacy of our templating approach. The {sup 29}Si NMR spectrum of the silica matrix was observed by an intermolecular cross-polarization experiment involving the {sup 1}H nuclei of TPA and the {sup 29}Si nuclei in the silica matrix. The efficiency of the cross-polarization interaction was used to investigate the degree to which the matrix formed a tight cage surrounding the template molecule. Bulk xerogels, prepared by gelation and slow drying of the corresponding sols, exhibited only weak interactions between the two sets of nuclei. Thin film xerogels, where drying stresses are greater, exhibited significantly increased interactions. Intramolecular cross-polarization experiments between the {sup 1}H and {sup 13}C nuclei of the template molecule demonstrated that much of the increased efficiency was a result of reduced rotational mobility of the TPA molecule.
  • Physical Description: 12 p.

Subject

  • Keyword: Zeolites
  • STI Subject Categories: 36 Materials Science
  • Keyword: Molecular Structure
  • Keyword: Nmr Spectra
  • Keyword: Pore Structure
  • Keyword: Structural Chemical Analysis
  • Keyword: Amorphous State
  • Keyword: Silica
  • Keyword: Nuclear Magnetic Resonance

Source

  • Journal Name: Journal of Physcial Chemistry; Other Information: Submitted to Journal of Physical Chemistry

Collection

  • Name: Office of Scientific & Technical Information Technical Reports
    Code: OSTI

Institution

  • Name: UNT Libraries Government Documents Department
    Code: UNTGD

Resource Type

  • Article

Format

  • Text

Identifier

  • Report No.: SAND99-1753J
  • Grant Number: AC04-94AL85000
  • Office of Scientific & Technical Information Report Number: 9019
  • Archival Resource Key: ark:/67531/metadc792441

Note

  • Display Note: OSTI as DE00009019
  • Display Note: Medium: P; Size: 12 pages
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