Adsorbed states of CO on dispersed metals: A high-resolution solid-state NMR study

Journal Article · Wed Mar 22 23:00:00 EST 1989 · Journal of Physical Chemistry; (USA)

DOI:https://doi.org/10.1021/j100343a067· OSTI ID:5113487

Duncan, T M ^[1]; Zilm, K W; Hamilton, D M ^[2]; Root, T W ^[3]

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1. AT and T Bell Labs., Murray Hill, NJ (USA)
2. Yale Univ., New Haven, CT (USA)
3. Univ. of Wisconsin, Madison (USA)

CO adsorbs on oxide-supported transition metals in three forms: linear- and bridge-bonded states on metal clusters and multicarbonyls on isolated single metal atoms. Recent broad-line {sup 13}C nuclear magnetic resonance (NMR) studies of adsorbed CO have demonstrated the ability to provide quantitative site distributions, descriptions of the adsorbate bonding and geometry, models for adsorbate motions, and metal particle geometries. This study reports the high-resolution {sup 13}C NMR spectra of CO adsorbed on silica-supported Rh and Ru obtained by magic-angle sample spinning, which corroborate the broad-line measurements and provide additional information. The salient features derived from the high-resolution spectra are the isotropic chemical shifts and chemical heterogeneity of the adsorbate states. The isotropic shifts support the results for linearly bonded CO and multicarbonyls extracted from broad-line spectra and allow refinement of the principal shielding components for these two species. The low heterogeneity for these sites indicates the metal particles contribute negligible susceptibility broadening, which suggests that on these highly dispersed samples the metal aggregates are two-dimensional, raftlike structures. Finally, comparison to the broad-line spectra reveals possible caveats of magic-angle spinning spectra of adsorbates: the apparent absence of components with large site heterogeneity, the inability to resolve components clearly differentiated in broad-line spectra, and site distributions inconsistent with volumetric uptake data.

• OSTI ID: 5113487
• Journal Information: Journal of Physical Chemistry; (USA), Journal Name: Journal of Physical Chemistry; (USA) Vol. 93:6; ISSN 0022-3654; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
CARBON 13
CARBON COMPOUNDS
CARBON ISOTOPES
CARBON MONOXIDE
CARBON OXIDES
CHALCOGENIDES
DATA
DISTRIBUTION
ELEMENTS
EVEN-ODD NUCLEI
EXPERIMENTAL DATA
INFORMATION
ISOTOPES
LIGHT NUCLEI
MAGNETIC RESONANCE
METALS
MINERALS
NMR SPECTRA
NUCLEAR MAGNETIC RESONANCE
NUCLEI
NUMERICAL DATA
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
PLATINUM METALS
RESONANCE
RHODIUM
RUTHENIUM
SILICA
SILICON COMPOUNDS
SILICON OXIDES
SORPTIVE PROPERTIES
SPATIAL DISTRIBUTION
SPECTRA
STABLE ISOTOPES
STRUCTURAL CHEMICAL ANALYSIS
SURFACE PROPERTIES
TRANSITION ELEMENTS