Luminescence and IR characterization of acid sites on alumina

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

DOI:https://doi.org/10.1006/jcat.1994.1086· OSTI ID:7197571

Shen, Yan-Fei; Suib, S L ^[1]; Deeba, M; Koermer, G S ^[2]

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1. Univ. of Connecticut, Storrs, CT (United States)
2. Engelhard Corporation, Menlo Park, NJ (United States)

Luminescence and infrared (IR) spectroscopies of pyridine and ammonia adsorption have been used to measure acidities of [gamma]-alumina. Neither luminescence nor IR spectra of pyridine adsorption show an Bronsted acidity on [gamma]-alumina pretreated to 400[degrees]C. However, luminescence emission data reveal four weak OH bands even when pretreatment is done at 600[degrees]C. Pyridine and subsequent water adsorption yield six luminescence emission bands. A red shift of the pyridine emission band is found when pretreatment or desorption temperature is increased. IR spectra of ammonia on alumina pretreated at 400[degrees]C show three deformation bands at 1452, 1465, and 1485 cm[sup [minus]1]. The first band is also observed together with a band at 1554 cm[sup [minus]1] even for pretreatment at 950[degrees]C, and it corresponds to NH[sup +][sub 4] formed from dissociative adsorption of ammonia, while the other two bands are assigned to ammonia adsorbed on Bronsted acid sites. These two bands disappear along with the appearance of a new band at 1429 cm[sup [minus]1], when deuterated alumina is pretreated at 400[degrees]C and subsequently subjected to ammonia. This new band at 1429 cm[sup [minus]1] is due to NH[sub 3]D[sup +] formed from ammonia adsorbed on acidic OD sites. Consequently, ammonia IR results demonstrate the existence of Bronsted acid sites on alumina pretreated at 400[degrees]C. 38 refs., 9 figs., 2 tabs.

• OSTI ID: 7197571
• Journal Information: Journal of Catalysis; (United States), Journal Name: Journal of Catalysis; (United States) Vol. 146:2; 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
ABSORPTION SPECTROSCOPY
ADSORPTION
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
AMMONIA
AZINES
BROENSTED ACIDS
CHALCOGENIDES
DEUTERIUM COMPOUNDS
EMISSION SPECTROSCOPY
HETEROCYCLIC COMPOUNDS
HYDRIDES
HYDROGEN COMPOUNDS
INORGANIC ACIDS
NITROGEN COMPOUNDS
NITROGEN HYDRIDES
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PYRIDINE
PYRIDINES
SORPTION
SORPTIVE PROPERTIES
SPECTROSCOPY
SURFACE PROPERTIES