Controlling Nucleation Pathways in Zeolite Crystallization: Seeding Conceptual Methodologies for Advanced Materials Design

Abstract

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.

Bio‐fuels production through waste tires pyrolytic oil upgrading over Ni‐W/zeolite composites derived from blast furnace slag

“…The uniformity of the presented zeolite structures can be attributed to the high purity of utilized silica (leached from BFS) and the long hydrothermal treatment time. Impurities in siliceous source limits the nucleation of zeolite and cause imperfect lattice shapes as reported in 36,37 . Generally, it can be said that the SEM interpretations for both ZA and ZX are strongly aligned with the XRD results in terms of their purity and crystallinity.…”

“…Impurities in siliceous source limits the nucleation of zeolite and cause imperfect lattice shapes as reported in. 36,37 Generally, it can be said that the SEM interpretations for both ZA and ZX are strongly aligned with the XRD results in terms of their purity and crystallinity.…”

Protozeolite‐Seeded Synthesis of Single‐Crystalline Hierarchical Zeolites with Facet‐Shaped Mesopores and Their Catalytic Application in Methanol‐to‐Propylene Conversion

“…[4,19,29,30] Notably, the seed-assisted synthesis method has gained considerable interest because of its accelerated crystallization rate, less usage of organic-structure directing agents (OSDAs), and the ability to create zeolite particles with nanosize and/or mesopores via adjustable crystallization behaviour. [31][32][33][34][35][36] The hierarchical zeolites synthesized by this method are often polycrystalline aggregates formed by the aggregation of small crystallites. [34,37,38] Thus, the resultant zeolite crystals are fragile under thermal/hydrothermal conditions and these small particles generally undergo further agglomeration during the catalysis process.…”

“…Besides, the crystalline framework of zeolites is often damaged and a large number of defects and/or some amorphous regions are generated near the mesopore edges after removing these templates [4, 19, 29, 30] . Notably, the seed‐assisted synthesis method has gained considerable interest because of its accelerated crystallization rate, less usage of organic‐structure directing agents (OSDAs), and the ability to create zeolite particles with nanosize and/or mesopores via adjustable crystallization behaviour [31–36] . The hierarchical zeolites synthesized by this method are often polycrystalline aggregates formed by the aggregation of small crystallites [34, 37, 38] .…”

Manipulation of amorphous precursors to enhance zeolite nucleation

“…The multitude of (alumino)silicate species makes it challenging to identify a single growth unit, thereby negating the use of supersaturation as a reliable metric for predicting crystallization. 25 Moreover, growth units can potentially evolve in their speciation and concentration throughout zeolite synthesis, [26][27][28][29] which allows for multiple crystallization pathways to occur simultaneously (e.g. both classical and nonclassical mechanisms).…”