Physico-Chemical nanomaterials science
Hierarchical zeolites as efficient catalysts for substituted 4-bromo-2,3-dihydro-1H-inden-1-ols dehydration
Kurmach M.M.1, Konysheva K.M.1, Lozovytska O.I.1, Babiy S.B.2, Shvets O.V1, Fetiukhin V.M.2
1 L.V. Pisarzhevsky Institute of Physical Chemistry of the NAS of Ukraine,.  Prospect Nauki 31, Kyiv-03028, Ukraine
E-mail: mazinator3710@ukr.net
2I.F.lab LTD, 
Murmanska str 5, Kyiv-02660, Ukraine

Substituted indenes are used as ligands for new type stereoselective catalysts for polymerization of α-olefines. Typical method for their production is dehydration of 4-bromo-2,3-dihydro-1H-inden-1-ol and its derivatives on different acid catalyst.  Process is complicated by such undesirable reactions such as formation of dimers and bromine elimination. Hierarchical zeolites are promising catalysts for a variety of catalytic process including bulk substrates due to their developed external surface and, consequently, high concentration of active sites available for them. It was expected that due to high developed external and reduced diffusion limitations surface hierarchical zeolites could provide high selectivity for their dehydration.
B-, Ga- and Al-containing hierarchical zeolites were obtained using different Gemini-type surfactants as structure-directing agents (SDA). Significant decrease in particle size allow to increase values of external surface area and mesopore volume values of which achieved up to 700 m2·g–1 and 1,4 cm3·g–1, consequently. Zeolites possessed a high concentration of Brønsted (BAS) and Lewis acid sites (LAS) (50 – 400 µmole·g–1) available for bulk molecules, fraction of which is achieved 85%. 
Type and concentration of elements incorporated into zeolite crystalline framework determines ratio of Lewis and Brønsted acid sites concentrations (ratio BLC) and their strength. Ga- and B-containing hierarchical zeolites due to high fraction of weak and medium BAS provide high selectivity in 4-bromo-2,3-dihydro-1H-inden-1-ol dehydration (selectivity >96%, complete conversion), while Al-BEA and Al-MTW were more selective for 4-bromo-2-methyl-2,3-dihydro-1H-inden-1-ol dehydration. Al-MOR and Al-MFI possessed by high activity but low selectivity due to high fraction of strong BAS.