Modeling spontaneous formation of precursor nanoparticles in clear-solution zeo...

• Author(s): Miguel Ângelo da Silva Jorge ; Scott Auerbach ; Peter Monson
• Date: 2005
• Persistent ID: http://hdl.handle.net/10216/49951
• Origin: Repositório Aberto da Universidade do Porto
• Subject(s): Ciências Físicas; Química; Química molecular
• Document Type: Article
• Language: English

Description

We present a lattice model describing the formation of silica nanoparticles in the early stages of the clear-solution templated synthesis of silicalite-1 zeolite. Silica condensation/hydrolysis is modeled by a nearest-neighbor attraction, while the electrostatics are represented by an orientation-dependent, short-range interaction. Using this simplified model, we show excellent qualitative agreement with published experimental observations. The nanoparticles are identified as a metastable state, stabilized by electrostatic interactions between the negatively charged silica surface and a layer of organic cations. Nanoparticle size is controlled mainly by the solution pH, through nanoparticle surface charge. The size and concentration of the charge-balancing cation are found to have a negligible effect on nanoparticle size. Increasing the temperature allows for further particle growth by Ostwald ripening. We suggest that this mechanism may play a role in the growth of zeolite crystals.