Solid-state [sup 1]H MAS NMR characterization of [gamma]-alumina and modified [gamma]-aluminas

Journal Article · Fri Jul 01 04:00:00 EDT 1994 · Journal of Catalysis; (United States)

DOI:https://doi.org/10.1006/jcat.1994.1187· OSTI ID:6798876

DeCanio, E C; Edwards, J C ^[1]; Bruno, J W ^[2]

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1. Texaco Research and Development Department, Beacon, NY (United States)
2. Wesleyan Univ., Middletown, CT (United States)

[gamma]-alumina is used extensively as a catalyst support material. [sup 1]H single pulse MAS and CPMG T[sub 2]/CSA-filter NMR experiments have been performed in order to characterize the hydroxyl structure of [gamma]-alumina, as well as fluoride- and phosphate-modified [gamma]-alumina materials. The authors have shown that problems associated with the strong homonuclear dipole-dipole interactions between protons of neighboring OH groups can be overcome by isotopic dilution of the alumina surface protons by deuterium exchange. Partially deuterated [gamma]-alumina yields resonances at around -0.3, 0.3, 1.5, 2.4, 4.0, 5.0, 6.5, 7.1, and 7.8 ppm. CPMG T[sub 2]/CSA-filter NMR experiments performed on alumina calcined at 700[degrees]C show that five different types of hydroxyl groups are present. CPMG T[sub 2]/CSA-filter NMR of deuterated F/Al[sub 2]O[sub 3] produces a resonance at 11.5 ppm in addition to a range of resonances between -0.2 and 7 ppm. NMR data for calcined P/Al[sub 2]O[sub 3] and P-Mo(12)/Al[sub 2]O[sub 3] (wt% P = 0.0-10.0) show that polymeric orthophosphates produce a resonance at 3.4 ppm, while the monomeric orthophosphate species gives rise to a resonance at 1.2 ppm. 41 refs., 6 figs.

• OSTI ID: 6798876
• Journal Information: Journal of Catalysis; (United States), Journal Name: Journal of Catalysis; (United States) Vol. 148:1; ISSN 0021-9517; ISSN JCTLA5
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CATALYST SUPPORTS
CHALCOGENIDES
DEUTERIUM COMPOUNDS
HYDROGEN COMPOUNDS
ISOTOPIC EXCHANGE
MAGNETIC RESONANCE
MOLYBDENUM COMPOUNDS
NUCLEAR MAGNETIC RESONANCE
OXIDES
OXYGEN COMPOUNDS
PHOSPHORUS COMPOUNDS
REFRACTORY METAL COMPOUNDS
RESONANCE
TRANSITION ELEMENT COMPOUNDS