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1633460 
Journal Article 
The role of the zeolite channel architecture and acidity on the activity and selectivity in aromatic transformations: The effect of zeolite cages in SSZ-35 zeolite 
Zilkova, N; Bejblova, M; Gil, B; Zones, SI; Burton, AW; Chen, C; Musilova-Pavlackova, Z; Kosova, G; Cejka, J 
2009 
Yes 
Journal of Catalysis
ISSN: 0021-9517
EISSN: 1090-2694 
266 
1 
79-91 
English 
WOS:000269326800010 
A series of zeolites differing in the channel architecture and acidity was investigated in toluene disproportionation, together with toluene and p-xylene alkylation with isopropyl alcohol. Zeolites with one- to three-dimensional 10-ring and 12-ring channels with and without cages, and those having 12-12-10 and 12-10-10-ring channel systems were studied. It was shown that general relationship of increasing zeolite activity with increasing pore diameter and pore connectivity is not valid as the size of some 12-ring channels (Beta, MCM-68) is comparable with 10-ring channels (ZSM-5, SSZ-35). In addition, the presence of cages in the structure of SSZ-35 and MCM-58 attributes the unusual catalytic behavior of these zeolites. SSZ-35 and MCM-58 zeolites behave in both toluene reactions such as three-dimensional large-pore zeolites. Subtle differences between zeolites of similar pore sizes and dimensionality can be usually explained based on the differences in the acidity of the individual zeolites. In p-xylene alkylation SSZ-35 exhibited high conversion with the highest selectivity to 1-isopropyl-2,5-dimethyl benzene and a low rate of deactivation. The presence of 18-ring cages in the channels of 10-ring zeolite SSZ-35 (STF) gives rise to an unusual catalytic behavior of this zeolite by comparison to other 10-ring zeolites. SSZ-35, possessing channels of 0.54 x 0.57 nm in diameter, exhibits catalytic activity in transformation of aromatic hydrocarbons that is similar to large-pore zeolites. 18-Ring cages enable the formation of relatively bulkier transition states while the diffusion of the product molecules out of the 10-ring channel system is not slowed down due to 10-ring windows. In addition, the channel system of SSZ-35 prevents the formation of coke precursors. (C) 2009 Elsevier Inc. All rights reserved. 
Zeolite architecture; Cage effect; Acidity; Alkylation; Disproportionation; SSZ-33; SSZ-35; MCM-58; MCM-68