sup 13 C NMR studies of CO adsorbed on supported rhodium catalysts: Effects of alkali promotion
Journal Article
·
· Journal of Catalysis; (United States)
OSTI ID:7253018
- Univ. of Wisconsin, Madison (United States)
Changes in the chemical properties of silica-supported Rh catalysts on potassium promotion are observed in the {sup 13}C NMR spectra of adsorbed CO. Catalysts prepared by incipient wetness with 2.5% Rh loading and Rh:K ratios of 1:0, 3:1, and 1:3 show relatively constant CO adsorption site character but have large changes in relative populations of linear, bridging, isolated dicarbonyl, and metal-bound CO. Back-bonded metal electrons on CO produce a Gaussian peak near 275 ppm and indicate a transition to metallic behavior of the underlying Rh at high promotion levels. Purely electrostatic effects are shown to be too small to cause the shifts reported for IR and NMR peak positions. Alkali promotion inhibits the breakup of Rh particles and formation of isolated dicarbonyl sites during CO adsorption, probably by the conversion of surface {minus}OH groups to {minus}OK groups.
- OSTI ID:
- 7253018
- Journal Information:
- Journal of Catalysis; (United States), Journal Name: Journal of Catalysis; (United States) Vol. 137:1; ISSN 0021-9517; ISSN JCTLA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
01 COAL, LIGNITE, AND PEAT
010408 -- Coal
Lignite
& Peat-- C1 Processes-- (1987-)
10 SYNTHETIC FUELS
100200 -- Synthetic Fuels-- Production-- (1990-)
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ADSORPTION
ALKALI METALS
CARBON 13
CARBON COMPOUNDS
CARBON ISOTOPES
CARBON MONOXIDE
CARBON OXIDES
CATALYST SUPPORTS
CATALYSTS
CATALYTIC EFFECTS
CHALCOGENIDES
CHEMICAL PREPARATION
CHEMICAL REACTIONS
ELEMENTS
EVEN-ODD NUCLEI
FISCHER-TROPSCH SYNTHESIS
ISOTOPES
LIGHT NUCLEI
MAGNETIC RESONANCE
METALS
NUCLEAR MAGNETIC RESONANCE
NUCLEI
OXIDES
OXYGEN COMPOUNDS
PLATINUM METALS
POTASSIUM
PROMOTERS
QUANTITY RATIO
RESONANCE
RHODIUM
SILICON COMPOUNDS
SILICON OXIDES
SORPTION
SORPTIVE PROPERTIES
STABLE ISOTOPES
SURFACE PROPERTIES
SYNTHESIS
TRANSITION ELEMENTS
010408 -- Coal
Lignite
& Peat-- C1 Processes-- (1987-)
10 SYNTHETIC FUELS
100200 -- Synthetic Fuels-- Production-- (1990-)
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ADSORPTION
ALKALI METALS
CARBON 13
CARBON COMPOUNDS
CARBON ISOTOPES
CARBON MONOXIDE
CARBON OXIDES
CATALYST SUPPORTS
CATALYSTS
CATALYTIC EFFECTS
CHALCOGENIDES
CHEMICAL PREPARATION
CHEMICAL REACTIONS
ELEMENTS
EVEN-ODD NUCLEI
FISCHER-TROPSCH SYNTHESIS
ISOTOPES
LIGHT NUCLEI
MAGNETIC RESONANCE
METALS
NUCLEAR MAGNETIC RESONANCE
NUCLEI
OXIDES
OXYGEN COMPOUNDS
PLATINUM METALS
POTASSIUM
PROMOTERS
QUANTITY RATIO
RESONANCE
RHODIUM
SILICON COMPOUNDS
SILICON OXIDES
SORPTION
SORPTIVE PROPERTIES
STABLE ISOTOPES
SURFACE PROPERTIES
SYNTHESIS
TRANSITION ELEMENTS