Physico-Chemical nanomaterials science
Hierarchical zeolites as perspective catalysts for acid-base and redox reactions
Kurmach M.M., Konysheva K.M., Shvets O.V.
L.V. Pisarzhevsky Institute of Physical Chemistry of the NAS of Ukraine,.  Prospect Nauki 31, Kyiv-03028, Ukraine
E-mail: mazinator3710@ukr.net

Hierarchical zeolites are efficient catalysts for many redox and acid base process including bulk substrates due to their developed external surface and, consequently, high fraction of active sites available for bulk molecules. Here we presented the results of hierarchical zeolites catalytic properties investigations.
Hierarchical zeolite nanosheets (BEA, MTW and MOR), nanorods (MTW and MOR) and nanosponges (BEA and MTW) 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 Bronsted acid sites concentrations (ratio BLC) and catalytic properties of resulting material. Ga- and B-containing hierarchical zeolites due to high fraction of weak BAS provide high selectivity in 2-bromoindanone dehydration (selectivity >96%, complete conversion), while Al-containing zeolite are less selective. Meanwhile, Al-containing zeolites with high concentration of strong BAS are active in acetal production (including bulk di-butoxybutane), coumarine synthesis by Pechmann reaction. Ni-dopped Al-MFI and MOR nanosheets provide high selectivity by di-branched products in hexane isomerization. 
Ti-, Sn-, Zr-containing hierarchical zeolites possessed a high concentration of LAS at the negligible small concentration of BAS and make them perspective catalyst for a number of a process. For example, due significant LAS concentration Ti-, Sn- and Zr-containing MTW, BEA and MFI zeolites provide high catalytic activity in ethyl lactate transformation (EL) into lactide (EL conversion up to 47% with selectivity 41%) and anis aldehyde transformation into 4-methoxybenzyl-sec-butyl ether (conversion of aldehyde up to 84%). Cu-dopped Zr-MTW are effective catalysts for Lebedev process (production of 1,3-butadiene from ethanol) with 81% conversion and 61% selectivity by target products.