Nanocomposites and nanomaterials

Zeolite nanocomposites with variable acid a basic properties – effective catalysts for fine chemical synthesis and industrial reaction
Shvets O.V., Kurmach M.M., Konysheva K.M.
Department of porous substances and materials, Institute of Physical Chemistry of the NAS of Ukraine. Prospect Nauki, 31, Kyiv-03028, Ukraine. 
E-mail: alexshvets@ukr.net

Hierarchical Al-, Ga- and B-silicate zeolites of structural types MOR, BEA, MFI and MTW with morphology of nanorods, nanosheets or approximate to spherical nanoparticles and different chemical composition are obtained [1]. For hierarchical zeolites with MOR, BEA, MFI and MTW topology by different methods it was found that the strength of Brønsted acid centers increases in the series BEA < MFI < MTW < MOR. The decrease in the average value of the strength of Brønsted acid centers (increase in pKa by 0.4 – 0.9) for zeolites with nanosheets morphology compared to isostructural analogues with nanorods (MOR) or nanoparticles (BEA) morphology [2].
Al-, Ga- and B-silicate hierarchical zeolites of structural types MOR, BEA, MFI and MTW with morphology of nanorods, nanolayers or nanoparticles, due to the presence of optimal strength of Brønsted acid centers are active and highly selective catalysts for dehydration in the mild conditions (yield of the target product 97 – 99%). Hierarchical zeolites of structural types MOR, BEA, MFI of different morphology with supported nickel nanoparticles show high selectivity in the process of hydroisomerization of linear hexane (~ 70% at 275 °C, and 20% for the most valuable product 2,2-dimethylbutane), which allows us to consider them as promising catalysts for this reaction. Formation of the basic centers in zeolite composites with different nature and structure allows obtaining effective catalysts for the Gewald reaction and cycloaddition reactions under carbon dioxide pressure. 
The role of the hierarchy of zeolite materials is manifested both  in increasing the accessibility of zeolite active centers on the surface of mesopores compared to traditional zeolites and in changing the strength of acid a basic centers located on the external surface, which changes the activity and selectivity of catalysts based on hierarchical zeolites in acid-base reactions.

1.	Shvets O.V., Konysheva K.M., Shamzhy M.V., et all. // Catalysis Today – 2019.- P. 115–122.
2.	Konysheva K.M., Yaremov P.S., Chernenko Zh.V., Filonenko S.M., Shvets O.V. // Theoret. Exper. Chem. – 2017.-53.-P. 410-415.