Reassessment of zeolite and molecular sieve framework infrared vibrations

Journal Article · Wed Oct 01 00:00:00 EDT 1986 · J. Catal.; (United States)

DOI:https://doi.org/10.1016/0021-9517(86)90286-1· OSTI ID:5648106

Szostak, R; Thomas, T L

To develop the infrared spectroscopy technique for molecular sieve characterization, the authors have utilized the known substitution of gallium for aluminum into the tetrahedral sites of the faujasite structure to identify and assign the infrared active framework vibrations. All materials described in this study were confirmed to be highly crystalline and free of extraneous matter. The framework vibration modes examined appear between 600 and 1200 cm/sup -1/ in the infrared spectrum and have been attributed to the symmetric (600-900 cm/sup -1/) and asymmetric (900-122 cm/sup -1/) stretching vibrations of the T-O bonds. The previously assigned vibrational contribution to these bands for the faujasite materials was of the stretching vibrations O-T-O within the framework structure. The T atom indicates the inability of IR to discriminate between the two similar mass elements, aluminum and silicon. Since the T atom occupies the central position within this harmonic oscillator, the substitution of a heavier element such as gallium for the aluminum would be expected to shift the asymmetric but not the symmetric vibrations. However, if the oscillator contributing to these bands is due to the Si-O-T symmetric and asymmetric stretches (with T now denoting the elements aluminum, silicon or gallium) then both vibrations would shift when the heavier element, gallium, is substituted for aluminum. This has been previously suggested in studies of layered and clay materials. By examining the infrared symmetric stretching vibration region for the gallosilicate analogs of the zeolites type X and Y, the two possible vibrational group contributions would be distinguishable. Results are discussed. 12 references.

• Research Organization: Georgia Institute of Technology, Atlanta
• OSTI ID: 5648106
• Journal Information: J. Catal.; (United States), Vol. 101:2
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
MOLECULAR SIEVES
INFRARED SPECTRA
VIBRATIONAL STATES
ZEOLITES
ALUMINIUM
CRYSTAL STRUCTURE
DATA ANALYSIS
GALLIUM
MATERIAL SUBSTITUTION
SILICON
ADSORBENTS
ELEMENTS
ENERGY LEVELS
EXCITED STATES
INORGANIC ION EXCHANGERS
ION EXCHANGE MATERIALS
MATERIALS
METALS
MINERALS
SEMIMETALS
SPECTRA
400201* - Chemical & Physicochemical Properties