Multinuclear solid-state NMR investigation of the chemisorption of ammonia on. gamma. -alumina

Journal Article · Wed Dec 24 04:00:00 EST 1986 · J. Am. Chem. Soc.; (United States)

DOI:https://doi.org/10.1021/ja00286a001· OSTI ID:6803486

Majors, P D; Raidy, T E; Ellis, P D

The surface preparation-dependent interactions of ammonia with ..gamma..-alumina were explored via solid-state /sup 15/N and /sup 2/H NMR spectroscopies. /sup 15/N experiments demonstrated an unresolved distribution of ammonia surface species. Wide-line /sup 2/H line shapes and T/sub 1/ experiments indicate the presence of three motionally distinct deuteron resonances associated with the ammonia adsorbate. An ammonia resonance indicative of rapid motion about the threefold symmetry axis was isolated for the more sparsely hydrated surfaces and has been identified as the Lewis complex resonance. T/sub 1/ experiments show for this site that motion about the threefold axis is diffusive. A second deuterium resonance has been identified as a surface hydroxyl species by comparison with D/sub 2/O on ..gamma..-alumina experiments. This resonance shows a direct proportion of intensity with surface hydroxyl concentration, demonstrating the exchange of Broensted hydrogens with ammonia hydrogen atoms. A third component of the deuterium line shapes has been associated with surface Broensted ammonium species and appears to be comprised of a distribution of motionally averaged species. The experimental line shapes were simulated, and the relative Lewis and Broensted site populations of ammonia were estimated.

• Research Organization: Univ. of South Carolina, Columbia
• OSTI ID: 6803486
• Journal Information: J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 108:26; ISSN JACSA
• Country of Publication: United States
• Language: English

Related Subjects

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ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
AMMONIA
BROENSTED ACIDS
CHALCOGENIDES
CHEMICAL REACTIONS
CHEMISORPTION
DATA
DEUTERIUM COMPOUNDS
DIFFUSION
EXPERIMENTAL DATA
HYDRIDES
HYDROGEN COMPOUNDS
HYDROGEN TRANSFER
INFORMATION
INORGANIC ACIDS
ISOTOPES
LEWIS ACIDS
LIGHT NUCLEI
MAGNETIC RESONANCE
NITROGEN 15
NITROGEN COMPOUNDS
NITROGEN HYDRIDES
NITROGEN ISOTOPES
NMR SPECTRA
NUCLEAR MAGNETIC RESONANCE
NUCLEI
NUMERICAL DATA
ODD-EVEN NUCLEI
OXIDES
OXYGEN COMPOUNDS
RESONANCE
SEPARATION PROCESSES
SORPTION
SORPTIVE PROPERTIES
SPECTRA
STABLE ISOTOPES
SURFACE PROPERTIES