Towards the elucidation of the mechanisms of synthesis of zeolites

Zeolites are the principal solid catalysts in the chemical industry and are also widely used as adsorbents and detergent builders. Their remarkable topological diversity - 255 realized polymorphs to date, with over 300,000 more proposed - enables highly tunable shape-selective catalysis and adsorption. However, this same diversity underlies a longstanding challenge: how to direct the synthesis toward one desired polymorph among the many that can form under similar conditions. Organic molecules (structure-directing agents, SDAs), such as tetraalkylammonium ions, are traditionally used to stabilize specific pore architectures, but even the same SDA can yield different zeolite frameworks when parameters like temperature, silica-to-organic ratio, or water content are changed. This complexity reveals that the precise molecular mechanisms by which SDAs guide the assembly of silicates into particular zeolite polymorphs remain poorly understood.

In this presentation, I will discuss our recent molecular simulation work aimed at uncovering the stage at which zeolitic order emerges in the synthesis mixture, and the roles of nucleation and growth in steering the formation of distinct polymorphs. By integrating computational insights with experimental characterization and emerging machine-learning approaches, we seek to clarify how organic cations and silicates interact at the molecular level to form the diverse range of zeolite frameworks. This mechanistic understanding is key to designing new zeolites for catalysis and separations, allowing us to harness their structural diversity in a more predictive and targeted manner.

Speaker: Valeria Molinero, University of Utah