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less than 10%. Lower acid strength of active sites in (Ga)UTL is the
main reason for achieving around 50% of selectivity to xylenes.
In contrast, zeolite Beta shows again TMB conversions close to
thermodynamic values. Slightly higher conversions than thermo-
dynamic limits are due to the consecutive reaction of primary
products as well as some dealkylation of TMB (Fig. 10B).
indicate that isomorphously substituted extra-large pore zeolites
can be sufficiently active and even more selective catalysts for some
aromatic hydrocarbon transformations.
Acknowledgements
In the case of toluene alkylation (Fig. 10C), toluene conver-
sions over (Al)UTL and BEA are close to thermodynamic values
and selectivities to cymenes (primary products) are usually higher
The authors thank the Czech Science Foundation (Project No.
P106/12/0189) for financial support. J. Cˇ . appreciates very much the
Micromeritics Grant Program supporting his research activities.
◦
than 80%. The exceptions are at 250 C for zeolites (Al)UTL and BEA
(
short T-O-S values) when the toluene conversion is also influenced
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Please cite this article in press as: N. Zˇ ilková, et al., Transformation of aromatic hydrocarbons over isomorphously substituted UTL: Comparison