Solid-state magic-angle spinning /sup 27/Al NMR used to study alumina support and surface compound structure of catalysts
/sup 27/Al NMR can, in principle, be very useful for following the tetrahedral/octahedral ratio in alumina supports as a function of thermal treatment as has been demonstrated previously. Even with magic-angle spinning of highly crystalline ..cap alpha..-alumina (corundum), the NMR linewidth of /sup 27/Al is quite broad. This would lead one to surmise that it would not be feasible to observe the formation of surface compounds of the alumina support or active catalytic phases since the NMR signal of the surface phase would be masked by the bulk if the two phases were of comparable linewidth and chemical shift. What the authors demonstrate in this communication is that the surface and bulk phases of alumina need not have the same linewidth and, depending on the surface compounds formed, may have substantial chemical shifts relative to bulk Al/sup 3 +/. In the case of a NiMoP/Al/sub 2/O/sub 3/ hydrodesulfurization catalyst, at least, Al/sup 3 +/-containing surface phases are formed during calcination which can easily be distinguished from the bulk ..gamma..-Al/sub 2/O/sub 3/ support. 27 references.
- Research Organization:
- Yale Univ., New Haven, CT (USA)
- DOE Contract Number:
- AC02-81ER10829
- OSTI ID:
- 5353269
- Journal Information:
- J. Catal.; (United States), Vol. 97:1
- Country of Publication:
- United States
- Language:
- English
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ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
02 PETROLEUM
CATALYST SUPPORTS
SURFACE PROPERTIES
CATALYSTS
ALUMINIUM 27
ALUMINIUM OXIDES
CHEMICAL SHIFT
DESULFURIZATION
HYDROGENATION
LINE WIDTHS
MOLYBDENUM
NICKEL
NMR SPECTRA
NUCLEAR MAGNETIC RESONANCE
PHOSPHORUS
ALUMINIUM COMPOUNDS
ALUMINIUM ISOTOPES
CHALCOGENIDES
CHEMICAL REACTIONS
ELEMENTS
ISOTOPES
LIGHT NUCLEI
MAGNETIC RESONANCE
METALS
NONMETALS
NUCLEI
ODD-EVEN NUCLEI
OXIDES
OXYGEN COMPOUNDS
RESONANCE
SPECTRA
STABLE ISOTOPES
TRANSITION ELEMENTS
400201* - Chemical & Physicochemical Properties
020400 - Petroleum- Processing