15N solid-state NMR characterization of ammonia adsorption environments in 3A zeolite molecular sieves

G. P. Holland, Brian Cherry, T. M. Alam

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

The quantitative analysis of ammonia binding sites in 3A zeolite molecular sieves using solid-state 15N MAS NMR spectroscopy is reported. By utilizing 15N-enriched ammonia ( 15NH 3) gas, the different adsorption/binding sites within the zeolite were characterized as a function of NH 3 loading. Using 15N MAS NMR, multiple sites were resolved that have distinct cross-polarization dynamics, relaxation, and chemical shift behavior. A combination of 15N/ 23Na and 15N/ 27Al TRAPDOR NMR methods was used to demonstrate significant dipolar coupling between adsorbed ammonia molecules and both Na cations and Al framework species in the zeolite cage. An estimate of the 23Na- 15N and 27A1- 15N distance was obtained from simulation of the TRAPDOR results. Two-dimensional 1H → 15N CP-MAS NMR exchange spectroscopy was implemented to probe dynamics between the two primary adsorbed ammonia environments. In the 3A zeolite, the observed exchange process between the ammonia sites does not display a significant temperature dependence, indicating a spin-diffusion mechanism.

Original languageEnglish (US)
Pages (from-to)16420-16426
Number of pages7
JournalJournal of Physical Chemistry B
Volume108
Issue number42
DOIs
StatePublished - Oct 21 2004
Externally publishedYes

Fingerprint

Zeolites
Molecular sieves
absorbents
Ammonia
Adsorption
ammonia
Nuclear magnetic resonance
solid state
nuclear magnetic resonance
adsorption
Binding sites
Magnetic Resonance Spectroscopy
Binding Sites
shift
cross polarization
Chemical shift
spectroscopy
quantitative analysis
Nuclear magnetic resonance spectroscopy
chemical equilibrium

ASJC Scopus subject areas

  • Surfaces, Coatings and Films
  • Physical and Theoretical Chemistry
  • Materials Chemistry

Cite this

15N solid-state NMR characterization of ammonia adsorption environments in 3A zeolite molecular sieves. / Holland, G. P.; Cherry, Brian; Alam, T. M.

In: Journal of Physical Chemistry B, Vol. 108, No. 42, 21.10.2004, p. 16420-16426.

Research output: Contribution to journalArticle

Holland, G. P. ; Cherry, Brian ; Alam, T. M. / 15N solid-state NMR characterization of ammonia adsorption environments in 3A zeolite molecular sieves. In: Journal of Physical Chemistry B. 2004 ; Vol. 108, No. 42. pp. 16420-16426.
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