Simple organic structure directing agents for synthesizing nanocrystalline zeolites.

The synthesis of the ZSM-5 and beta zeolites in their nanosized form has been achieved by using simple alkyl-substituted mono-cationic cyclic ammonium cations as OSDA molecules. The particular combination of a cyclic fragment and a short linear alkyl-chain group (preferentially C) within the monocationic OSDA molecules allows directing the crystallization of nanosized zeolites with excellent solid yields (above 90%). Interestingly, the formation of the nanosized ZSM-5 and beta zeolites mostly depends on the size and nature of the cyclic fragment of the OSDA molecule, resulting in all cases in nanocrystalline solids with homogeneous distributions of particle sizes (∼10-25 nm) and controlled Si/Al molar ratios (∼15-30).

High-silica nanocrystalline Beta zeolites: efficient synthesis and catalytic application.

An efficient synthesis methodology to obtain homogeneous nanosized high-silica Beta zeolites (∼10-20 nm) with high solid yields (above 95%) using simple alkyl-substituted flexible dicationic OSDAs is described. These dicationic OSDAs allow the synthesis of nanosized Beta zeolites with different Si/Al ratios (15-30) in alkaline and fluoride media, resulting in nanocrystalline materials with different physico-chemical properties. These nanosized Beta zeolites show better catalytic behavior towards the industrially-relevant alkylation of benzene with propylene to obtain cumene compared with other commercially available nanosized Beta zeolites.

Direct Dual-Template Synthesis of MWW Zeolite Monolayers.

A two-dimensional zeolite with the topology of MWW sheets has been obtained by direct synthesis with a combination of two organic structure-directing agents. The resultant material consists of approximately 70% single and double layers and displays a well-structured external surface area of about 300 m(2) g(-1). The delaminated zeolite prepared by means of this single-step synthetic route has a high delamination degree, and the structural integrity of the MWW layers is well preserved.