In situ observation of homogeneous nucleation of nanosized zeolite A

Fan, Wei; O’Brien, Matthew G.; Ogura, Masaru; Sánchez‐Sánchez, Manuel; Martin, Christopher M.; Meneau, Florian; Kurumada, Ken-ichi; Sankar, Gopinathan; Okubo, Tatsuya

doi:10.1039/b510963a

Cited by 33 publications

(26 citation statements)

References 35 publications

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“…4 shows a clearer view of the scattering profile changes of the first two frames (log I(q) versus log q), before the onset of crystallisation. Unlike the report on zeolite A synthesis by Sankar et al, no marked features associated with the presence of clear primary units are visible in the SAXS scattering profile [15,19].…”

Section: Particles Size and The Guinier Regioncontrasting

confidence: 76%

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In situ synchrotron small-angle X-ray scattering study of MCM-41 crystallisation using Gemini surfactants

Gianotti¹,

Berlier²,

Costabello³

et al. 2007

Catalysis Today

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Section: Particles Size and The Guinier Regioncontrasting

confidence: 76%

“…Many research groups have shown that SAXS can be successfully employed to follow the crystallisation of ordered micro and mesoporous structures [14][15][16][17][18][19]. SAXS is a non-destructive method, does not require special sample preparation and permits the in situ reaction analysis.…”

Section: Introductionmentioning

confidence: 99%

In situ synchrotron small-angle X-ray scattering study of MCM-41 crystallisation using Gemini surfactants

Gianotti¹,

Berlier²,

Costabello³

et al. 2007

Catalysis Today

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“…3 ) are predominantly comprised of soluble monomers and/or small oligomers. Prior studies have shown that (alumino)silicate particles or sol gels in LTA growth solutions are sites for heterogeneous nucleation 24 , while homogeneous nucleation has been observed in solutions devoid of amorphous precursors 30 . The clear solutions used in this study differ from those of other zeolites, such as silicalite-1, which are predominantly suspensions of nanoparticles (1–6 nm) 31 – 33 that attach to crystal surfaces and undergo structural rearrangement to incorporate into the underlying crystal lattice 9 .…”

Section: Resultsmentioning

confidence: 99%

Transient modes of zeolite surface growth from 3D gel-like islands to 2D single layers

2018

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Zeolite crystallization occurs by multifaceted processes involving molecule attachment and nonclassical pathways governed by the addition of amorphous precursors. Here, we use scanning probe microscopy to monitor zeolite LTA crystallization in situ with a spatiotemporal resolution that captures dynamic processes in real time. We report a distinctive pathway involving the formation of gel-like islands from supersaturated solutions comprised of (alumino)silicate molecules. Three-dimensional assembly and evolution of these islands constitutes a unique mode of growth that differs from classical theories. Time-resolved imaging also reveals that growth can occur by (nearly) oriented attachment. At later stages of crystallization, a progressive transition to lower supersaturation shifts growth to a layered mechanism involving two-dimensional nucleation and spreading of layers. Here, we show that LTA crystallization occurs by multiple pathways, thereby reconciling putative hypotheses of growth mechanisms while also highlighting new modes of nonclassical crystallization that may prove relevant to other zeolites and related materials.

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“…During the early stages of zeolite synthesis, growth mixtures containing numerous amorphous precursors lead to crystallization by particle attachment, or CPA (4,22,25,26). As the synthesis nears completion, the consumption of precursors results in growth solutions containing mostly monomers where the predominant mode shifts to a classical mechanism; however, recent studies have shown that the use of organics as either structuredirecting agents (SDAs) (27)(28)(29) or zeolite growth modifiers (24,30) can selectively switch the mode of growth between CPA and monomer addition.…”

mentioning

confidence: 99%

In situ imaging of two-dimensional surface growth reveals the prevalence and role of defects in zeolite crystallization

Choudhary

Jain

Rimer

2020

Proc. Natl. Acad. Sci. U.S.A.

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Zeolite crystallization predominantly occurs by nonclassical pathways involving the attachment of complex (alumino)silicate precursors to crystal surfaces, yet recurrent images of fully crystalline materials with layered surfaces are evidence of classical growth by molecule attachment. Here we use in situ atomic force microscopy to monitor three distinct mechanisms of two-dimensional (2D) growth of zeolite A where we show that layer nucleation from surface defects is the most common pathway. Direct observation of defects was made possible by the identification of conditions promoting layered growth, which correlates to the use of sodium as an inorganic structure-directing agent, whereas its replacement with an organic results in a nonclassical mode of growth that obscures 2D layers and markedly slows the rate of crystallization. In situ measurements of layered growth reveal that undissolved silica nanoparticles in the synthesis medium can incorporate into advancing steps on crystal surfaces to generate defects (i.e., amorphous silica occlusions) that largely go undetected in literature. Nanoparticle occlusion in natural and synthetic crystals is a topic of wide-ranging interest owing to its relevance in fields spanning from biomineralization to the rational design of functional nanocomposites. In this study, we provide unprecedented insight into zeolite surface growth by molecule addition through time-resolved microscopy that directly captures the occlusion of silica nanoparticles and highlights the prevalent role of defects in zeolite crystallization.

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In situ observation of homogeneous nucleation of nanosized zeolite A

Cited by 33 publications

References 35 publications

In situ synchrotron small-angle X-ray scattering study of MCM-41 crystallisation using Gemini surfactants

In situ synchrotron small-angle X-ray scattering study of MCM-41 crystallisation using Gemini surfactants

Transient modes of zeolite surface growth from 3D gel-like islands to 2D single layers

In situ imaging of two-dimensional surface growth reveals the prevalence and role of defects in zeolite crystallization

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