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
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.