A powerful structure-directing agent for the synthesis of nanosized Al- and high-silica zeolite Beta in alkaline medium

Abstract

Purely siliceous and Al-containing nano-zeolite Beta (BEA) crystals were synthesized using 4,4′-trimethylenebis( N-methyl, N-benzyl-piperidinium) cations as structure-directing agent (SDA). The influence of the synthesis parameters (synthesis time and temperature, heating source) as well as the chemical composition of the precursor gel on the nature of the product and its particle size was investigated. Purely siliceous nano-zeolite Beta with a particle size of around 140 nm and single domains of around 30 nm in size was synthesized with a high level of reproducibility and stabilized in colloidal suspension. Aluminium-containing Beta zeolite (Al-BEA) crystals were prepared either under conventional hydrothermal treatment or under microwave irradiation. Stable colloidal suspensions of Al-BEA particles with a size of 200 nm were obtained, consisting of single domains in the range of 5–15 nm, depending on the nature of the heating mode.