Mechanistic principles of nanoparticle evolution to zeolite crystals

Davis, Tracy M.; Drews, Timothy O.; Ramanan, Harikrishnan; He, Chuan; Dong, Junfeng; Schnablegger, Heimo; Katsoulakis, Markos A.; Kokkoli, Efrosini; McCormick, Alon V.; Penn, R. Lee; Tsapatsis, Michael

doi:10.1038/nmat1636

Cited by 434 publications

(664 citation statements)

References 37 publications

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“…S9) after aging, the inorganic-organic species may mainly come from the tetrapropylammonium-containing silicates (21). Meanwhile, it is worth noting that the particle size of the solid intermediates became larger with the aging period, which is consistent with previous reports (25,26). These results indicate that the short-range order might have started to form during the aging stage, which creates an environment favorable for the immediate crystal growth under high temperatures, resulting in the synthesis on the order of seconds.…”

Section: Significancesupporting

confidence: 89%

Continuous flow synthesis of ZSM-5 zeolite on the order of seconds

Liu

Okabe

Anand

et al. 2016

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

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The hydrothermal synthesis of zeolites carried out in batch reactors takes a time so long (typically, on the order of days) that the crystallization of zeolites has long been believed to be very slow in nature. We herein present a synthetic process for ZSM-5, an industrially important zeolite, on the order of seconds in a continuous flow reactor using pressurized hot water as a heating medium. Direct mixing of a well-tuned precursor (90°C) with the pressurized water preheated to extremely high temperature (370°C) in the millimeter-sized continuous flow reactor resulted in immediate heating to high temperatures (240-300°C); consequently, the crystallization of ZSM-5 in a seed-free system proceeded to completion within tens of or even several seconds. These results indicate that the crystallization of zeolites can complete in a period on the order of seconds. The subtle design combining a continuous flow reactor with pressurized hot water can greatly facilitate the mass production of zeolites in the future. Z eolites have typically been synthesized via hydrothermal treatment, a process designed to artificially mimic the geological formation conditions of natural zeolites (1, 2). Depending on the targeted framework and composition, several hours to days (or even several weeks) are required to complete the synthesis of a crystalline product (3). As a great improvement over the hundreds or thousands of years required for the formation of natural zeolites, artificial synthesis on the order of days allows us more opportunities to obtain zeolites with tunable properties (4, 5). Nevertheless, the hydrothermal synthesis of zeolites has remained a time-consuming process. Long periods of hydrothermal treatment, for one thing, cause a burden on both energy efficiency and operational costs. Furthermore, pressure-tight vessels used for the hydrothermal treatment as well as harsh conditions therein make mechanistic studies using in situ techniques difficult to perform (6, 7). The complexity of crystallization, in turn, hinders the attempts at shortening the synthesis period. This dilemma explains to some extent the reason behind the long-held belief that crystallization of zeolites is extremely slow in nature.The other major hurdle for the widespread application of zeolites is the difficulty in mass production. Batchwise synthesis using autoclaves is convenient for basic laboratory investigations but poses several challenges--in terms of economic efficiency, quality control, and operation flexibility--when large-scale manufacturing is considered (8). In contrast, continuous flow process has proved to be beneficial in the production of various chemicals (9, 10). Due to the time-consuming hydrothermal treatment used for the synthesis of zeolites, however, making a direct switch from batchwise synthesis to continuous flow manufacturing is not easy. To realize continuous flow production, shortening the synthesis period is therefore an issue of the highest priority. Recently, we have developed an ultrafast route to synthesize indust...

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Section: Significancesupporting

confidence: 89%

Continuous flow synthesis of ZSM-5 zeolite on the order of seconds

Liu

Okabe

Anand

et al. 2016

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

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“…Mineral systems may crystallize through an amorphous precursor at sufficiently high supersaturation (5,20,46,(66)(67)(68)(69), but the mechanism of the transition is unclear for most systems. For calcium carbonate formed abiotically from aqueous solution, the ACC precursor phase is initially hydrated (64,66).…”

Section: Amorphous Phasesmentioning

confidence: 99%

Crystallization by particle attachment in synthetic, biogenic, and geologic environments

Yoreo

Gilbert

Sommerdijk

et al. 2015

Science

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1,672

1,637

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Field and laboratory observations show that crystals commonly form by the addition and attachment of particles that range from multi-ion complexes to fully formed nanoparticles. The particles involved in these nonclassical pathways to crystallization are diverse, in contrast to classical models that consider only the addition of monomeric chemical species. We review progress toward understanding crystal growth by particle-attachment processes and show that multiple pathways result from the interplay of free-energy landscapes and reaction dynamics. Much remains unknown about the fundamental aspects, particularly the relationships between solution structure, interfacial forces, and particle motion. Developing a predictive description that connects molecular details to ensemble behavior will require revisiting long-standing interpretations of crystal formation in synthetic systems, biominerals, and patterns of mineralization in natural environments.

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“…1 However, the self-assembly steps by which such important materials form are still not well understood and thus the synthesis of new topologies is still something of a hit and miss process. [2][3][4] Understanding the critical stages in microporous materials crystallisation is then clearly the first step towards realising the possibility of rational microporous materials design for specific purposes e.g. tailoring a material's properties for a specific catalytic reaction.…”

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confidence: 99%

Monitoring the coordination of aluminium during microporous oxide crystallisation by in situ soft X-ray absorption spectroscopy

et al. 2006

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An in situ cell, which is capable of obtaining time resolved soft X-ray data (200 eV , E , 3000 eV) under hydrothermal conditions has been developed and used to study the selfassembly processes occurring during microporous aluminophosphate crystallization.Many of the useful physical properties associated with zeotypes, such as ion-exchange capacity, molecular sieving and shape selectivity, originate from the presence of nanometre-sized channels and/or cages within their structure. Although they occur within the Earth's crust, a large demand on their usage has triggered major research efforts on the preparation of synthetic analogues of these minerals, the alteration of their properties by manipulation of their framework and the synthesis of new topologies altogether. 1 However, the self-assembly steps by which such important materials form are still not well understood and thus the synthesis of new topologies is still something of a hit and miss process. [2][3][4] Understanding the critical stages in microporous materials crystallisation is then clearly the first step towards realising the possibility of rational microporous materials design for specific purposes e.g. tailoring a material's properties for a specific catalytic reaction.Time-resolved in situ experiments using a variety of analytical techniques have been performed in an attempt to obtain such information. [2][3][4] The majority of these studies have concentrated on using scattering techniques to follow these processes since they are sensitive to structural ordering in the system. However, since selfassembly processes involve the ordering of atomic or molecular species, spectroscopic techniques can also yield important insight since they are more sensitive. For example, it has been possible to follow the behaviour of a small amount of a hetero-atom (an example being transition metal ions, which can be considered as a 'probe' species) to obtain information on these self-assembly processes. [5][6][7] However, such information can be considered at best indirect and is only possible to observe with hetero-atoms, which give a strong spectroscopic signature and which do not influence the phase formation processes unduly. It is far more useful therefore to follow the crystallisation behaviour of the major structural elements, although this is more difficult to achieve since their spectroscopic signatures are often comparatively weak or less detailed than the corresponding transition metal ion-substituted systems. Perhaps, the most relevant technique to obtain such molecular insight into the assembly processes under hydrothermal conditions is NMR, since it is particularly sensitive to changes in the local structure of the zeolite/zeotype atomic species. Indeed, it has been successfully employed to obtain detailed information regarding the formation of microporous systems. [8][9][10] However, the interpretation of NMR data is not always straightforward due to quadrupolar effects or line broadening as a result of interactions with paramagnetic species, such a...

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Mechanistic principles of nanoparticle evolution to zeolite crystals

Cited by 434 publications

References 37 publications

Continuous flow synthesis of ZSM-5 zeolite on the order of seconds

Continuous flow synthesis of ZSM-5 zeolite on the order of seconds

Crystallization by particle attachment in synthetic, biogenic, and geologic environments

Monitoring the coordination of aluminium during microporous oxide crystallisation by in situ soft X-ray absorption spectroscopy

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