Nanosized beta-zeolites with tunable particle sizes: Synthesis by the dry gel conversion (DGC) method in the presence of surfactants, characterization and catalytic properties

Nanosized beta-zeolites were synthesized using the dry gel conversion (DGC) method with tetraethylammonium hydroxide (TEAOH) as a structure-directing agent (SDA) in the presence of the surfactants: cetyltrimethylammonium bromide (CTMABr), chloride (CrMACl) and hydroxide (CTMAOH). The presence of the surfactant in the synthesis gel creates a confined environment and controls the formation of nanosized beta-zeolites with SiO2/Al2O3 ratios of 25-200. The beta-zeolites have uniform particle sizes of 35-60 nm with large BET and external surface areas. The particle size of the beta-zeolites depends on the concentration and type of counter-anion of the surfactant used. The catalytic properties of nanosized beta-zeolites, mainly concerning the role of internal and external acid sites, were evaluated by the isomerization/cracking of hexane and phenol alkylation with 1-octene. (C) 2008 Elsevier Inc. All rights reserved.