A core objective of synthesizing zeolites for widespread applications is to produce materials with properties and corresponding performances that exceed conventional counterparts. This places an impetus on elucidating and controlling processes of crystallization where one of the most critical design criteria is the ability to prepare zeolite crystals with ultrasmall dimensions to mitigate the deleterious effects of mass transport limitations. At the most fundamental level, this requires a comprehensive understanding of nucleation to address this ubiquitous materials gap. This Perspective highlights recent methodologies to alter zeolite nucleation by using seed-assisted protocols and the exploitation of interzeolite transformations to design advanced materials. Introduction of crystalline seeds in complex growth media used to synthesize zeolites can have wide-ranging effects on the physicochemical properties of the final product. Here we discuss the diverse pathways of zeolite nucleation, recent breakthroughs in seed-assisted syntheses of nanosized and hierarchical materials, and shortcomings for developing generalized guidelines to predict synthesis outcomes. We offer a critical analysis of state-of-the-art approaches to tailor zeolite crystallization wherein we conceptualize whether parallels between network theory and zeolite synthesis can be instrumental for translating key findings of individual discoveries across a broader set of zeolite crystal structures and/or synthesis conditions.

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The preparation of metastable zeolites is often restricted to a limited range of synthesis conditions, which is exemplified in commercial syntheses lacking organics to stabilize the crystal structure. In the absence of an organic structure-directing agent, interzeolite transformation is a common phenomenon that can lead to undesirable products or impurities. Many studies have investigated the substitution of Si and Al in zeolite frameworks with alternative elements (heteroatoms) as a means of tailoring the properties of zeolites; however, relatively few studies have systematically explored the impact of heteroatoms on interzeolite transformations and their concomitant effects on zeolite crystallization. In this study, we examine methods to prepare isostructures of faujasite (FAU), which is one of the most commercially relevant zeolites and also a thermodynamically metastable structure. A survey of multivalent elements revealed that zinc is capable of stabilizing FAU at high temperatures and inhibiting its frequent transformation to zeolite gismondine (GIS). Using combined experimental and computational studies, we show that zinc alters the chemical nature of growth mixtures by sequestering silicates. Zinc heteroatoms incorporate in the FAU framework with a loading-dependent coordination. Our collective findings provide an improved understanding of driving forces for the FAU-to-GIS interzeolite transformation where we observe that heteroatoms (e.g., zinc) can stabilize zeolite FAU over a broad range of synthesis conditions. Given the growing interest in heteroatom-substituted zeolites, this approach to preparing zinc-containing FAU may prove applicable to a broader range of zeolite structures.

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The mechanisms of many zeolitic processes, including nucleation and interzeolite transformation are not fully understood owing to complex growth mixtures that obfuscate in situ monitoring of molecular events. In this...