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Sun, H. Q.; Wang, Jianguo; Jin-xian, HU; Zhou, Ji

doi:10.1023/a:1019086310123

Cited by 7 publications

(5 citation statements)

References 17 publications

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“…For instance, a general trend is that higher temperatures increase the rate of crystal growth relative to nucleation, leading to fewer (but larger) crystals . Intermediate synthesis temperatures or systems that utilize a two-stage process have been shown to generate products with properties (e.g., crystal size) between those of high- and low-temperature syntheses. − Cundy and Cox proposed an explanation for these observations by considering the mechanistic differences between zeolite nucleation and growth, assuming that the former is proportional to a flux of species and the latter is a balance between dissolution and attachment, with each being influenced differently by temperature. Based on activation energies, it has also been suggested that crystal growth rates are determined by surface kinetics, which can be affected by ion size and mobility of aluminosilicates and SDAs .…”

Section: Zeolite Crystal Growthmentioning

confidence: 99%

The Current Understanding of Mechanistic Pathways in Zeolite Crystallization

Mallette,

Shilpa,

Rimer

2024

Chem. Rev.

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Zeolite catalysts and adsorbents have been an integral part of many commercial processes and are projected to play a significant role in emerging technologies to address the changing energy and environmental landscapes. The ability to rationally design zeolites with tailored properties relies on a fundamental understanding of crystallization pathways to strategically manipulate processes of nucleation and growth. The complexity of zeolite growth media engenders a diversity of crystallization mechanisms that can manifest at different synthesis stages. In this review, we discuss the current understanding of classical and nonclassical pathways associated with the formation of (alumino)silicate zeolites. We begin with a brief overview of zeolite history and seminal advancements, followed by a comprehensive discussion of different classes of zeolite precursors with respect to their methods of assembly and physicochemical properties. The following two sections provide detailed discussions of nucleation and growth pathways wherein we emphasize general trends and highlight specific observations for select zeolite framework types. We then close with conclusions and future outlook to summarize key hypotheses, current knowledge gaps, and potential opportunities to guide zeolite synthesis toward a more exact science.

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Section: Zeolite Crystal Growthmentioning

confidence: 99%

The Current Understanding of Mechanistic Pathways in Zeolite Crystallization

Mallette,

Shilpa,

Rimer

2024

Chem. Rev.

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“…Sun et al (2000) came to similar conclusions synthesizing [Fe]-MFI via a two-stage strategy. The lower temperature (393 K) resulted in a much higher number of crystals and thus ultimately smaller sizes after completing growth at 443 K: ±300 nm instead of ±4000 nm in the case of a single stage at 443 K …”

Section: Changing the Physical Environmentmentioning

confidence: 99%

“…167 Sun et al ( 2000) came to similar conclusions synthesizing [Fe]-MFI via a two-stage strategy. The lower temperature (393 K) resulted in a much higher number of crystals and thus ultimately smaller sizes after completing growth at 443 K: ±300 nm instead of ±4000 nm in the case of a single stage at 443 K. 168 In line with these MFI findings in the presence of OSDA, Sang et al (2006) reported the synthesis of a NaY (FAU), typically without OSDA, comparing a conventional hydrothermal synthesis and a non-isothermal route. A two-stage temperature program (24 h at 313 K followed by 48 h at 333 K) was applied to the precursor mixture.…”

Section: ■ Changing the Physical Environmentmentioning

confidence: 99%

Zeolite Synthesis under Nonconventional Conditions: Reagents, Reactors, andModi Operandi

Deneyer

Devos

et al. 2020

Chem. Mater.

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A myriad of tetrahedral molecular sieve frameworks, often siliceous, can be calculated in silico. Only a tiny fraction (<0.1%) of these can be synthesized on purpose. Only a small fraction of these available frameworks, mostly those composed of only Si and Al as T-atoms, i.e. true zeolites, are used commercially. A gap thus exists between what should be possible (thermodynamically) and what can be produced (kinetically) and used in real life. Even if a synthesis is successful (in industry or academia), flexibility with regard to synthesis parameters -in terms of time, amount of unit operations, OSDA-efficiency, etc. -as well as the obtained material properties -in terms of Si/Al ratio, Al-distribution, T-atom variety, crystal size, etc. -remains limited. These limitations are not surprising since conventional zeolite syntheses, i.e. hydrothermal synthesis in batch from amorphous or soluble Si-and Al-sources, have limited degrees of freedom (DOF). Typically, the type of ingredients, their ratios, a constant temperature, synthesis time and the absence or presence of agitation are varied. In order to take new steps towards more cost-competitive syntheses, and more importantly, zeolites with a greater flexibility in terms of structural properties, this review highlights all DOFs that can be introduced in addition to or on top of the conventional way of synthesis. By doing this, a distinction is made between non-conventional DOFs that influence the chemistry of the system (e.g. interzeolite conversion, charge density mismatch approach, ionothermal or free-radical assisted synthesis) and non-conventional DOFs that influence the physical environment (e.g. ultrasounds, alternative energy via microwaves or continuous set-ups). The review concludes with learnings, practical insights and future opportunities. In other words: which zeolite synthesis strategies really make a difference and which ones are just tweaking around the edges?

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“…的两步法可以制备 ZSM-5 小晶体颗粒. Sun 等 [25] 报道了采用两步法可以合成具有 300 nm 均一尺寸的 Fe-ZSM-5 沸石分子筛. Li 等 [26] 研究了两步法中的线性生长速率以及最终收率问题.…”

Section: 在有机模板剂存在下利用低温成核高温晶化unclassified

“…Small crystals can be acquired by a temperature-varying two-step method (lower temperature for nucleation and higher temperature for crystal growth) in templated systems. For example, Sun et al [25] synthesized small crystal Fe-ZSM-5 with a uniform crystallite size of about 300 nm using this method. Li et al [26] investigated the linear growth rate and final yield of silicalite using the two-step temperature-varying process.…”

Section: English Textmentioning

confidence: 99%