M. Hunger et al., METHYL TERTIARY-BUTYL ETHER SYNTHESIS ON ZEOLITE HBETA INVESTIGATED BY IN-SITU MAS NMR-SPECTROSCOPY UNDER CONTINUOUS-FLOW CONDITIONS, MICROPOROUS AND MESOPOROUS MATERIALS, 22(1-3), 1998, pp. 357-367
In situ MAS NMR spectroscopy was applied to investigate the synthesis
of methyl tertiary-butyl ether (MTBE) over zeolite HBeta (n(Si)/n(Al)
= 15.8) under continuous-flow conditions. Preliminary catalytic tests
with on-line gas chromatographic analysis of the reaction products rev
ealed an activity of zeolite HBeta in the MTBE synthesis comparable wi
th that of Amberlyst-15. By exposing the calcined zeolite, filled into
an MAS NMR rotor, to a flow of nitrogen gas loaded with methanol and
isobutene, the interaction of these reactant molecules with the zeolit
e OH groups and the dimerization and oligomerization of isobutene were
studied. C-13 MAS NMR spectroscopy performed during the conversion of
a methanol/isobutene mixture over zeolite HBeta yielded signals at 77
ppm to 90 ppm due to secondary and tertiary carbon atoms of alkoxy co
mplexes formed at the zeolite framework. (C) 1998 Elsevier Science B.V
. All rights reserved.