Predicting New Zeolites: A Combination of Thermodynamic and Kinetic Factors

Abstract

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.

Necessity of Heteroatoms for Realizing Hypothetical Aluminophosphate Zeolites: A High-Throughput Computational Approach

“…To accelerate the discovery of new zeolitic materials, millions of hypothetical zeolite structures have been predicted via various computational methods. − Furthermore, many structure evaluation criteria have been proposed to predict the feasibility of the hypothetical structures. − However, their experimental realization still requires a priori knowledge on whether heteroatoms in addition to Al and P sources are necessary to be introduced into the synthetic system. Previous studies concerning the prediction of whether heteroatoms are necessary for specific AlPO structures are based on the substitution of Al atoms in pure AlPOs by heteroatoms.…”

Ranking the Synthesizability of Hypothetical Zeolites with the Sorting Hat

“…Restricting the range of correlations or discarding all angular information leads to degradation of classification performance, indicating that the structural features that distinguish real and hypothetical zeolites involve angular correlations and patterns in the relative positions of second and third neighbor atoms -i.e., at length scales beyond the typical indicators that have been hypothesized in previous studies [11][12][13][14][15][16][17][18].…”

“…Which hypothetical zeolites are most likely synthesizable, and in which chemical composition? Previous attempts to answer these questions [11][12][13][14][15][16][17][18] have relied on intuitive guesses for structural descriptors such as rings and angles, which provide incomplete [19] and thus biased results. In the present work, we answer all these questions via rigorous data science methods combining unsupervised and supervised machine learning, [20] along with the generalized convex hull (GCH) description of thermodynamic stability, [21] yielding a new and powerful approach for sorting real [22] and hypothetical [2][3][4][5] zeolites, as well as finding promising zeolite candidates and suggesting likely chemical compositions for them.…”

Vapour-phase-transport rearrangement technique for the synthesis of new zeolites

“…Zeolites are crystalline porous materials used for many applications, including gas separation and catalysis 1–3 . Although millions of thermodynamically stable structures have been predicted under ambient conditions, until now, the zeolite community has only recognised ~250 different zeolite topologies 4 . Such discrepancy between the numbers of proposed zeolite topologies and those produced via traditional hydrothermal approaches has prompted the development of alternative strategies for zeolite synthesis.…”