Quantum chemical molecular models of oxides. 2. Methanol adsorption on silica and zeolites

Journal Article · Thu Mar 05 04:00:00 EST 1992 · Journal of Physical Chemistry

DOI:https://doi.org/10.1021/j100184a040· OSTI ID:255264

Pelmenschikov, A G; Morosi, G; Gamba, A ^[1]

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1. Universita` di Milano (Italy)

Quantum chemical molecular models are used to interpret the IR spectra of methoxy species formed in methanol adsorption on silica and zeolites. The calculations are carried out by the ab initio SCF MO method with 3-21G basis set, using a scaling procedure to correct the ab initio C-H stretching frequencies. Comparison of the calculated and observed frequencies shows that at low coverage of silica the structure is the most relevant among the physically adsorbed methanol species, while at high coverages the physically adsorbed methanol tends to form cyclic hydrogen-bonded polymers with the O{sub 3}SiOH group participation. Assignment of the C-H stretching bands at 2980 and at 2870 cm{sup {minus}1} to the methoxy group {r_arrow}SiO(CH{sub 3}) {hor_ellipsis}Al {l_arrow} in zeolites, suggested in the literature, is in large disagreement with the predicted vibrational frequencies for this structure. The authors suggest that these bands belong to strongly physically adsorbed methanol, stabilized on the bridging OH groups by two hydrogen bonds. 41 refs., 5 figs., 7 tabs.

• Sponsoring Organization: USDOE
• OSTI ID: 255264
• Journal Information: Journal of Physical Chemistry, Journal Name: Journal of Physical Chemistry Journal Issue: 5 Vol. 96; ISSN JPCHAX; ISSN 0022-3654
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
40 CHEMISTRY
ABSORPTION SPECTROSCOPY
ADSORPTION
MATHEMATICAL MODELS
METHANOL
SILICA
SORPTIVE PROPERTIES
VIBRATIONAL STATES
ZEOLITES