Nucleation and Crystal Growth Features of EMT-Type Zeolite Synthesized from an Organic-Template-Free System

Ng, Eng-Poh; Goupil, Jean‐Michel; Vicente, Aurélie; Fernandéz, Christian; Retoux, R.; Valtchev, Valentin; Mintova, Svetlana

doi:10.1021/cm3035455

Cited by 69 publications

(42 citation statements)

References 36 publications

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“…[10][11][12] These suspended primary nanoparticles measuring 1-2 nm have been characterized using 29 Si NMR and scattering techniques such as SAXS and DLS. 17,18 This achievement was in full accordance with the predicted phase diagram. 13,14 Recently, this work was extended to precursor clear solutions containing different organic SDAs by integrating SAXS, DLS and NMR in a unied characterisation scheme.…”

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confidence: 87%

Nucleation in complex multi-component and multi-phase systems: general discussion

Price¹,

Rimez²,

Sun³

et al. 2015

Faraday Discuss.

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Kenneth Harris opened a general discussion of the paper by Herma Cuppen: It is well established from solid-state NMR and other techniques that the NH 3 + group in crystalline amino acids undergoes rapid rotation about the C-NH 3 + bond. Is the phase transition between the b and a phases of DL-norleucine associated with any signicant discontinuity in the rate of this motion, and/or the temperature dependence of the rate of this motion? Furthermore, is there any evidence for disorder (dynamic or static) of the alkyl chain of the norleucine molecules in the a and b phases, and if so, does the nature of this disorder change signicantly at the phase transition?Herma Cuppen answered: Rotation barriers about the C-NH 3 + bond depend on the motive of the hydrogen bonding network in the crystalline phases. For DLnorleucine this motive stays intact during the transition, and I therefore do not expect a large difference for the two phases. The changes occur where the aliphatic chains interact. In a previous study, 1 we determined the rotation barrier of the methyl group by means of molecular dynamics simulations for both phases. We found them to be identical, and to be in agreement with experimental values for DL-norvaline 2 and DL-norleucine. 3 We did not nd any correlation between internal movement of the molecules and the onset of the transition. 1. J. A. van den Ende and H. M. Cuppen, Cryst. Growth Des., 2014, 14, 3343.This journal is

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confidence: 87%

Nucleation in complex multi-component and multi-phase systems: general discussion

Price¹,

Rimez²,

Sun³

et al. 2015

Faraday Discuss.

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“…In organic free precursor suspension small isolated gel particles are formed after slow mixing, which decreases noncontrolled polymerization of aluminosilicate species. 26 The use of TMA and TEA as co-structure directing agents in EMT synthesis did not result in substantial physicochemical changes in the products. Only traces of organic cations were found in the crystalline phase.…”

Section: ■ Results and Discussionmentioning

confidence: 98%

Control of Na-EMT Zeolite Synthesis by Organic Additives

Georgieva

Vicente

Fernandéz

et al. 2015

Crystal Growth & Design

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Organic additives were used to control the formation of EMT-type zeolite in a sodium-rich initial system. Triethanolamine was employed as a nucleation suppression agent able to complex the aluminum during the synthesis of the EMT-type zeolite. The commonly used tetramethylammonium (TMA) chloride and tetraethylammonium (TEA) chloride as structure directing agents in zeolite synthesis were also employed in this study. The triethanolamine has the most pronounced effect on the crystal growth process of the EMT-type zeolite. The use of triethanolamine resulted in the formation of large crystals (100 nm) with the framework composition different from the counterpart obtained in the organic-free system. Therefore, the function of triethanolamine is attributed to the immobilization of Al in the initial gel and thus partial suppression of zeolite nucleation. The immobilization of a part of Al resulted in the EMT zeolite crystals with a higher Si/Al ratio (1.4). In contrast, the TMA and TEA organic additives have a limited impact on the physicochemical properties of the EMT crystals, the latter being a consequence of large presence of Na in the system. The bulky TMA and TEA ions prevent the aluminosilicate precursor species from agglomeration and formation of dense gels and thus resulting in the crystallization of nanosized EMT zeolite crystals (10−20 nm). ■ INTRODUCTIONZeolites are commonly synthesized from aluminosilicate hydrogels under hydrothermal conditions in the presence of a mineralizing agent (OH − , F − ) and inorganic and/or organic structure-directing agent (SDA), which predetermines to some extent the framework type formed. 1,2 Typically, organic molecules employed as structure-directing agents (SDAs) are trapped in zeolite micropore space and have to be eliminated by combustion or chemical treatment in order to open zeolite porosity. Besides playing a template function and thus determining the micropore space, the SDA agents stabilize the zeolite framework 3 and often control zeolite crystal morphology. 4 Extensive use of SDAs in zeolite synthesis resulted in the discovery of many different framework types. 5 The use of organic SDAs also has certain drawbacks such as (i) high cost of final product, (ii) generation of environmentally undesirable gases due to high temperature combustion of the template, 6 (iii) formation of defects in the zeolite framework during post synthesis treatment, and (iv) even decomposition of zeolite during template elimination. 7 Organic compounds have also been applied in the synthesis of zeolite crystals in order to control the nucleation process and thus to influence the particle size. According to Charnell, 8 the addition of 2,2′,2″-nitrilotriethanol (triethanolamine or TrEA) to zeolite A synthesis gels leads to growth of larger crystals. He proposed that the observed increase in the size of the crystals is due to the "stabilizing and buffering" effect of the TrEA. Recent studies have also confirmed these observations. 9−12 Compared to other organic additives, TrEA can extend the...

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“…Data in Figure correspond to syntheses at a fixed temperature (100 °C), heating time (7 days), and water content; however, it is well‐known that changes in these parameters, among others, can significantly alter the kinetic phase diagram ,. For instance, lower temperatures (<100 °C) favor FAU formation, whereas ANA or cancrinite (CAN) preferentially form at higher temperatures (>100 °C) .…”

Section: Resultsmentioning

confidence: 99%

Synthesis Strategies for Ultrastable Zeolite GIS Polymorphs as Sorbents for Selective Separations

Oleksiak

Ghorbanpour

Conato

et al. 2016

Chemistry A European J

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What is the most significant result of this study? In this study,w ed iscovered that subtle differences in crystal poly-morph structure can have ap rofound influence on material properties. The remarkable aspect of the two polymorphs in this particular study-GIS types P1 and P2-is the fact that their topology is nearly identical, yet as light rotation in the framework along with the replacement of one aluminum atom in the unit cell with as ili-con atom is sufficient to change the thermal stability of the material by more than af actor of two. This unexpected result could potentially impact the design of zeolites for ah ost of applications requiring (hydro)thermally robust isostructures. What was the inspiration for this cover design? When designing the cover,w ew anted to accomplish two objectives. The first was to highlight the hierarchical nature of our col-laborative research that spanned multiple length scales:t hat is, from macroscopic adsorption studies and microscopic materials characterization to atomistic modeling. The cover image highlights bulk sorbents that can be used for separations, am icroscopic image of az eolite crystal framework, and an individual pore operating as as ize-exclusion sieve. As econd aspect that we wanted to emphasize was the relevance of our findings to applications in the energy and chemicals industries. In our study,w eu sed ac ommer-cially viable approach to prepare GIS-type zeolites. To this end, their performance as selective sorbents may prove beneficial for expanding this work beyond the benchtop to be of practical use in industrial separations or adsorption technologies. What other topics are you working on at the moment? The research programs of the three principal investigators-Grabow,M otkuri, and Rimer-all fall under the general umbrella of nanoporous materials. Each of us studies zeolites, but for different applications-Grabow and Rimer focus on catalysis, whereas Mot-kuri, in addition to zeolites, is also interested on metal-organic frameworks for their sorption/separation applications. We are continuing to investigate aw ide range of open framework materials for these applications. An underlying theme of our work is the elu-cidation of structure-performance relationships, and the design of novel pathways to generate new/improved materials in pursuit of advancing these fields of research beyond current state-of-the-art technologies. Invited for the cover of this issue are the groups of R. K. Motkuri and J. D. Rimer at the Pacific Northwest National Laboratory and University of Houston, respectively.T he image depicts bulk sorbents that can be used for separations, am icroscopic image of az eolite crystal framework,a nd an individualp ore operating as as ize-exclusion sieve. Read the full text of the ar

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Nucleation and Crystal Growth Features of EMT-Type Zeolite Synthesized from an Organic-Template-Free System

Cited by 69 publications

References 36 publications

Nucleation in complex multi-component and multi-phase systems: general discussion

Nucleation in complex multi-component and multi-phase systems: general discussion

Control of Na-EMT Zeolite Synthesis by Organic Additives

Synthesis Strategies for Ultrastable Zeolite GIS Polymorphs as Sorbents for Selective Separations

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