Choline-mediated synthesis of zeolite ERS-7 <i>via</i> an excess fluoride approach

Bae, Juna; Hong, Suk Bong

doi:10.1039/c8cc06106h

Cited by 4 publications

(7 citation statements)

References 20 publications

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“…FER is calculated to be the preferred zeolite phase with a synthesis energy of −1.008 eV/TO 2 followed closely by RUT ( E syn = −0.999 eV/TO 2 ). This is in accordance with the experimental study of Bae et al where FER and RUT are the synthesis products at lower fluoride concentrations when SDA4 is utilized in aluminosilicate media, with FER being the main product (Table ). In fact, Lee et al also stated that RUT was always obtained as an impurity using SDA4 with a very small amount of Na + present.…”

Section: Resultsmentioning

confidence: 99%

“…Since this information is not present in the experiments reported in Table , we do not have, currently, enough information to try to explain why the calculated synthesis energy of ESV is higher than that of AST in the aluminosilicate composition (Table ). Nevertheless, the experiments at HF/SDA = 1.0 indicate (Table 1 of ref ) that AST was obtained at Si/Al = 20, hence hinting that this phase could also be obtained at HF/SDA = 1.5 and Si/Al ca. 9, according to our prediction.…”

Section: Resultsmentioning

confidence: 99%

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The Directing Role of Aluminum in the Synthesis of PST-21 (PWO), PST-22 (PWW), and ERS-7 (ESV) Zeolites

Altundal,

Sastre

2023

J. Phys. Chem. C

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Zeolites are a diverse class of crystalline microporous materials of, mainly, aluminosilicate chemical composition. Organic structure-directing agents (OSDAs) are generally utilized in zeolite synthesis to drive the outcome to a specific zeolite phase. In addition to OSDA, the presence and content of aluminum in the gel play a role in driving the synthesis under specific conditions. The structure-directing role of aluminum as well as fluoride in zeolite synthesis was explored through the analysis of three recently synthesized aluminosilicate zeolites, PST-21 (PWO), PST-22 (PWW), and ERS-7 (ESV), using a force field simulation approach. An updated and recently proposed method based on the calculation of “synthesis energy” is used to predict the stability of zeolites at pure-silica and aluminosilicate gel compositions, also able to include fluoride anions as well as OSDAs, and hence largely general. The results are not only demonstrating that the calculated structures with lowest “synthesis energy” correspond to those experimentally obtained under “standard” (meaning HF/SDA = 1) synthesis conditions but also that new structures obtained under the recently introduced “excess fluoride approach” are those which follow with energy slightly larger than the lowest, as calculated from the list of competing zeolites. With this method, we were able to rationalize the structure-directing effect of aluminum, in the presence of fluoride and OSDAs, in the synthesis of zeolites.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

The Directing Role of Aluminum in the Synthesis of PST-21 (PWO), PST-22 (PWW), and ERS-7 (ESV) Zeolites

Altundal,

Sastre

2023

J. Phys. Chem. C

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“…40,[74][75][76] The excess fluoride approach (HF/OSDA = 2) also allowed them to synthesize a high-silica (Si/ Al = 14) version of zeolite ERS-7 (ESV) using choline (Ch + ) ions. 77 Considering the unit cell composition and multinuclear MAS NMR results, they suggested that some F À anions paired with Ch + located within large 17-hedral ([4 6 5 4 6 5 8 2 ]) picnicbasket-shaped cages make the resulting zeolite more siliceous.…”

Section: Fluoride Anions As An Inorganic Synthesis Parametermentioning

confidence: 99%

Synthesis strategies to control the Al distribution in zeolites: thermodynamic and kinetic aspects

Bae

Dusselier

2023

Chem. Commun.

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“…Despite its simplicity, choline, when used together with various alkali and/or alkaline earth metal cations, can direct the synthesis of more than 10 different zeolite structures, many of which are different from those crystallized in the presence of TMA + or TEA + . We recently synthesized a high-silica (Si/Al = 14) version of zeolite ERS-7 (ESV) using this OSDA in excess fluoride conditions (HF/OSDA = 2.0) . Given that choline gave other phases like ferrierite when HF/OSDA ≤ 1.0, the excess fluoride approach may be a valuable tool to obtain zeolites with known framework structures but new compositions.…”

Section: Excess Fluoride Approachmentioning

confidence: 99%

“…37 We recently synthesized a high-silica (Si/Al = 14) version of zeolite ERS-7 (ESV) using this OSDA in excess fluoride conditions (HF/OSDA = 2.0). 38 Given that choline gave other phases like ferrierite when HF/OSDA ≤ 1.0, the excess fluoride approach may be a valuable tool to obtain zeolites with known framework structures but new compositions. We also note that, like as-made PST-21 and PST-22, the F − content in our high-silica ERS-7, although synthesized in the presence of a large concentration of this anion, is not so high.…”

Section: High-silica Ers-7mentioning

confidence: 99%

Rediscovery of the Importance of Inorganic Synthesis Parameters in the Search for New Zeolites

Shin

Hong

2019

Acc. Chem. Res.

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Conspectus Zeolites and related crystalline microporous materials with cavities and channels of molecular dimensions are of major importance for applications ranging from ion-exchange to adsorption and to catalysis. Because their unique shape-selective properties are closely related to the size, shape, and dimensionality of the intracrystalline channels and cavities, much interest has been devoted to the discovery of novel zeolitic materials over the last several decades. As a result, a dramatic expansion in the structural domain of crystalline microporous materials, as well as in their compositional range, has been achieved. This is largely due to the development of innovative synthetic strategies, for example, organic structure-directing agent (OSDA) design, introduction of heteroatoms like Ge in OSDA-mediated zeolite synthesis, topotactic transformation of two-dimensional layered zeolite precursors, assembly−disassembly−organization−reassembly method, etc. However, although many of these methodologies are quite successful in finding unprecedented zeolite structures, the resulting materials tend to be (hydro)thermally unstable and are often commercially impractical from a manufacturing perspective because of the high cost of the OSDA and/or heteroatom employed. Therefore, we focused on inorganic synthesis parameters as the key phase selectivity factor that has received relatively little attention in the search for new industrially relevant zeolites. This Account describes our recent efforts to find previously undiscovered aluminosilicate zeolites by boosting the roles of inorganic structure-directing agents (ISDAs) in the presence of OSDAs. They include the multiple inorganic cation and excess fluoride approaches, which aim to promote a synergistic cooperation between ISDAs and/or OSDAs and thus to hold a rational design concept, although the latter is not friendly to the practical zeolite manufacturing process due to the toxicity of fluoride. Using these two approaches, we were able to synthesize not only the second generation (PST-29) and four higher generations (PST-20 (RHO-G5), PST-25 (RHO-G6), PST-26 (RHO-G7), and PST-28 (RHO-G8)) of the RHO family of embedded isoreticular zeolites but also three other novel zeolite structures (EU-12, PST-21, and PST-22). We also explored the synthesis of a number of heteroatom-containing aluminophosphate (AlPO4) molecular sieves with different framework structures and unusually high framework charge density through the cooperative structure direction of alkali metal and small OSDA cations or under wholly inorganic conditions. Although we need to clarify the nature and extent of interactions between the inorganic cations and framework components in synthesis mixtures, we believe that our synthetic concepts, shedding new light on the importance of inorganic synthesis parameters, will open a door for achieving many other novel zeolite structures and compositions.

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Choline-mediated synthesis of zeolite ERS-7 via an excess fluoride approach

Cited by 4 publications

References 20 publications

The Directing Role of Aluminum in the Synthesis of PST-21 (PWO), PST-22 (PWW), and ERS-7 (ESV) Zeolites

The Directing Role of Aluminum in the Synthesis of PST-21 (PWO), PST-22 (PWW), and ERS-7 (ESV) Zeolites

Synthesis strategies to control the Al distribution in zeolites: thermodynamic and kinetic aspects

Rediscovery of the Importance of Inorganic Synthesis Parameters in the Search for New Zeolites

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