INTERACTION OF METHANOL WITH OH GROUPS OF ZEOLITES - COMPARISON OF THEORY AND EXPERIMENT

Citation
D. Nachtigallova et L. Kubelkova, INTERACTION OF METHANOL WITH OH GROUPS OF ZEOLITES - COMPARISON OF THEORY AND EXPERIMENT, Nuovo cimento della Societa italiana di fisica. D, Condensed matter,atomic, molecular and chemical physics, biophysics, 19(11), 1997, pp. 1735-1742
Citations number
17
Categorie Soggetti
Physics
ISSN journal
03926737
Volume
19
Issue
11
Year of publication
1997
Pages
1735 - 1742
Database
ISI
SICI code
0392-6737(1997)19:11<1735:IOMWOG>2.0.ZU;2-R
Abstract
The nature of methanol interact;ion complexes with bridging hydroxyls of zeolites is studied experimentally and theoretically. Results of ca lculations using HF, DFT, and MP2 methods on a large H2OH-Si-O-SiH2-OH -AlH2-O-SiH2OH are compared with experimental studies, particularly H- 1 broad line and FTIR fragment spectroscopies on H-mordenite and H-ZSM -5. Both experimental and theoretical studies predict the hydrogen-bon ded complex of methanol with zeolites. Two local minima of the hydroge n-bonded complex with a different orientation of methanol are found on the potential energy surface. In both structures, two active sites of zeolite are separated by one skeletal oxygen. The calculated adsorpti on enthalpies of both structures fall into the interval of measured ad sorption heats. The calculated vibrational OH frequencies are in reaso nable agreement with the experimentally measured frequencies. The calc ulations are also performed on a larger fragment which includes 4-oxyg en ring and a part of the zeolite channel. The results obtained with t his fragment are similar to those obtained with smaller fragments.