Predicting New Zeolites: A Combination of Thermodynamic and Kinetic Factors

Zeolites are a special class of inorganic compounds which potentially possess an infinite variety of different structures that are energetically very close to each other. Although the databases of hypothetical zeolite frameworks, which are thermodynamically close to the ground state, contain hundreds of thousands of entries, the number of experimentally obtained frameworks (currently 235) is essentially smaller. We discuss kinetic factors, which should be taken into account along with the thermodynamic ones to explain such great inconsistency and predict more thoroughly new robust zeolite frameworks. In addition to the thermodynamic factors, which determine energetically favorable structures, we consider structural parameters that provide the easiest ways of the structure assemblage. Exploring the existing zeolites, we derive geometrical and topological criteria that should be obeyed when the framework is being formed in the reaction gel. Resting upon these criteria, we extract from the databases of hypothetical zeolite frameworks those frameworks which are the most prospective for synthesis. We discuss also the problem of the purposeful sampling of proper organic structure directing agents and propose a list of them for a target synthesis of the selected hypothetical frameworks.