ИСТИНА

Zeolites are crystalline porous aluminosilicates. They are widely used as catalysts in industrial processes of petrochemistry, fine organic synthesis and biomass processing. Aluminum atoms can be located in the zeolite crystal lattice in nonequivalent crystallographic positions (T-positions) and they are associated with catalytic acid sites. There are 9 such positions in BEA zeolite. Depending on the location, the acid sites may have different catalytic activity. Therefore, the purpose of this work was to determine the distribution of aluminum over crystallographic positions by the high-quality 27 Al MAS NMR method in BEA zeolites synthesized in different media. The samples studied are denoted as following: BEA-X-Y, where X = 50, 200 or 250 (SiO2/Al2O3 ratio), Y = F (fluoride medium) or OH (alkaline medium). BEA-X-OH samples were supplied by Zeolyst company, BEA-X-F samples were synthesized by us.