A powerful structure-directing agent for the synthesis of nanosized Al- and high-silica zeolite Beta in alkaline medium

MFI-type zeolite is a crystalline microporous aluminosilicate with an intersecting two-dimensional pore structure and well-defined windows of approximately 0.55 nm. It generally crystallizes in high silica to alumina ratios, leading to a rather hydrophobic character. This makes it an attractive adsorbent for removing organic pollutants from wastewater. However, separating the conventional powdery-zeolites from the media after treatment is difficult because they require considerable time to settle. They also trigger filter clogging. In this work, high silica MFI-type zeolite, namely, silicalite-1, was synthesized on the surfaces of hollow glass microspheres to develop a floating adsorbent with high hydrophobicity. Tetraethylorthosilicate and tetrapropylammonium hydroxide were used as the additional silica source and structure directing agent, respectively. The crystallization of silicalite-1 on hollow glass microspheres was performed using hydrothermal synthesis at 180 °C or 150 °C for 40 h using a precursor sol with a molar composition of 3SiO2:1TPA:14EtOH:286H2O. The surface coverage and crystallinity of the as-prepared samples were optimized, and the floatability and adsorption performance of the optimized sample were investigated. Well-covered microspheres were obtained when hydrothermal synthesis was conducted at 180 °C using 0.5 g of hollow glass microspheres and 15 g of a precursor sol adjusted to pH 12.5. The balance between the dissolution rate of the hollow glass microspheres and the crystallization rate of silicalite-1 appeared to be the key factor in the successful synthesis.

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Syntheses of high-silica zeolites in urea/choline chloride deep eutectic solvent

Canadian Journal of Chemistry ◽

10.1139/cjc-2016-0115 ◽

2016 ◽

Vol 94 (6) ◽

pp. 533-540 ◽

Cited By ~ 6

Author(s):

Zheng Sonia Lin ◽

Yining Huang

Keyword(s):

Choline Chloride ◽

Deep Eutectic Solvent ◽

Reaction Times ◽

Ammonium Ion ◽

Structure Directing Agent ◽

Nmr Spectrum ◽

Local Ordering ◽

High Silica ◽

High Silica Zeolites ◽

Urea Decomposition

This paper presents the first example of high-silica and siliceous zeolite synthesis in the urea/choline chloride mixture as a deep eutectic solvent (DES) using F– as the mineralizing agent. A urea/choline chloride mixture was previously used as solvent to prepare AlPO4-based microporous materials SIZ-2 and AlPO-CJ2. However, generating these materials depends on the formation of ammonium ion as a structure-directing agent (SDA) that is the side product of urea decomposition. In the present study, we show that several highly siliceous zeolites with targeted topologies (MFI, BEA, MEL, and MTN) can be purposely synthesized by adding SDAs of choice rather than relying on solvent decomposition. The Si atoms in zeolite Beta synthesized in a urea/choline chloride mixture exhibit exceptionally high local ordering as shown in a 29Si MAS NMR spectrum. The synthesis of ZSM-11 using eutectic solvents or ionic liquid has not been reported. The major challenge in ZSM-11 synthesis is the intergrown structure formed with ZSM-5 due to the high similarity in their topologies. The present work shows that preparation of pure ZSM-11 can be achieved in urea/choline chloride DES using either DPHMII or DECDMPI as SDA. Using a urea/choline chloride mixture rather than alcohol-based traditional nonaqueous solvents is the key for the success of preparing phase-pure ZSM-11 free of any MFI intergrowths. This is because some alcohols can serve as SDA for MFI. The use of urea/choline chloride based DES eliminates the potential templateing effect of solvent for MFI formation. For MTN zeolite, morphology may be controlled in urea/choline chloride by choosing different SDAs. The disadvantage of this system is the long reaction times.

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Synthesis of high-silica ZSM-5 with seeds in the presence of ethanol and amine

Cerâmica ◽

10.1590/0366-69132019653752705 ◽

2019 ◽

Vol 65 (375) ◽

pp. 378-387

Author(s):

T. R. D. Mendonça ◽

J. R. Santos ◽

L. R. A. Sarmento ◽

D. C. M. Silva ◽

O. M. S. Cysneiros ◽

...

Keyword(s):

Crystallite Size ◽

Organic Compounds ◽

Nitrogen Adsorption ◽

Structure Directing Agent ◽

X Ray ◽

Synthesis Conditions ◽

Combined Use ◽

Cracking Reaction ◽

High Silica ◽

Alternative Structure

Abstract The possibility of crystallization of ZSM-5 with high Si/Al ratio was evaluated through the combined use of crystallization seeds and organic compounds that are not conventional directing agents for ZSM-5 (ethanol, methylamine, ethylamine, propylamine, butylamine, isopropylamine and diethylamine) in order to find a less toxic and costly route of synthesis. In addition, the influence of the stirring during the crystallization step on the properties of the ZSM-5 obtained in these synthesis conditions was verified. The obtained zeolites were analyzed by X-ray diffractometry in order to understand the effects of the templates. The analyses of NH3-TPD, nitrogen adsorption, SEM, and TG/DTA were performed for the samples with better crystallinity. The procedure was successfully employed for the synthesis of MFI samples using propylamine as an alternative structure-directing agent. Its mean crystallite size ranged from 23 to 24 nm and was efficient in the cracking reaction of n-hexane.

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Hydrothermal synthesis of high silica zeolite Y using tetraethylammonium hydroxide as a structure-directing agent

Chemical Communications ◽

10.1039/c6cc06786g ◽

2016 ◽

Vol 52 (86) ◽

pp. 12765-12768 ◽

Cited By ~ 14

Author(s):

Dawei He ◽

Danhua Yuan ◽

Zhijia Song ◽

Yansi Tong ◽

Yaqi Wu ◽

...

Keyword(s):

Thermal Stability ◽

Hydrothermal Synthesis ◽

Zeolite Y ◽

Hydrothermal Stability ◽

Structure Directing Agent ◽

Tetraethylammonium Hydroxide ◽

High Silica

Zeolite Y with a SiO2/Al2O3 ratio of 7.76 and outstanding thermal stability and hydrothermal stability is synthesized using TEAOH as an SDA.

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Polytype distributions in low-defect zeolite beta crystals synthesized without an organic structure-directing agent

Microporous and Mesoporous Materials ◽

10.1016/j.micromeso.2015.12.022 ◽

2016 ◽

Vol 225 ◽

pp. 210-215 ◽

Cited By ~ 11

Author(s):

Yukichi Sasaki ◽

Yoko Yoshida ◽

Craig A.J. Fisher ◽

Takuji Ikeda ◽

Keiji Itabashi ◽

...

Keyword(s):

Zeolite Beta ◽

Structure Directing Agent ◽

Organic Structure

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Eco-friendly synthesis of high silica zeolite Y with choline as green and innocent structure-directing agent

Chinese Journal of Catalysis ◽

10.1016/s1872-2067(18)63167-5 ◽

2019 ◽

Vol 40 (1) ◽

pp. 52-59 ◽

Cited By ~ 2

Author(s):

Dawei He ◽

Danhua Yuan ◽

Zhijia Song ◽

Yunpeng Xu ◽

Zhongmin Liu

Keyword(s):

Zeolite Y ◽

Structure Directing Agent ◽

High Silica

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Synthesis of Dense High-Silica Zeolite Beta Membranes with Controllable Orientation for n-Butanol Recovery from Dilute Aqueous Solution

Crystal Growth & Design ◽

10.1021/acs.cgd.8b01862 ◽

2019 ◽

Vol 19 (6) ◽

pp. 3166-3171 ◽

Cited By ~ 3

Author(s):

Yun Li ◽

Ning Ma ◽

Xiufeng Liu ◽

Baoquan Zhang

Keyword(s):

Aqueous Solution ◽

Zeolite Beta ◽

Dilute Aqueous Solution ◽

Butanol Recovery ◽

High Silica

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Structural and High Resolution Studies Of B-Zeolite Catalysts Using TEM and Fourier Transform Processing Techniques

MRS Proceedings ◽

10.1557/proc-111-161 ◽

1987 ◽

Vol 111 ◽

Author(s):

Miguel Jóse-Yacamán ◽

J. G. Pérez-Ramírez ◽

D. R. Acosta ◽

J. P. Gilson ◽

G. C. Edwards

Keyword(s):

Fourier Transform ◽

High Resolution ◽

Zeolite Beta ◽

Zeolite Catalysts ◽

Shale Oil ◽

Organic Template ◽

Tetraethylammonium Hydroxide ◽

High Silica ◽

Selective Adsorbent ◽

Processing Techniques

Zeolite Beta, synthesized in 1967 (1), is the first example of a large pore, high silica zeolite (SiO2O3 > 20) prepared in the presence of an organic template (Tetraethylammonium Hydroxide). Zeolite NU-2, whose synthesis has been reported in 1982 (2) seems to be related to the zeolite Beta. Although Zeolite Beta has been claimed as useful catalyst in hydrocracking (3), cracking (4), dewaxing (5), hydrotreating (6), shale oil (7) and Fisher-Tropsh products (B) conversions and as a selective adsorbent in the separation of alkylaromatics (9); this zeolite has not been extensively characterized in the open literature.

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When two bad data sets are better than one

Acta Crystallographica Section A Foundations and Advances ◽

10.1107/s2053273314098143 ◽

2014 ◽

Vol 70 (a1) ◽

pp. C185-C185

Author(s):

Stef Smeets ◽

Lynne McCusker ◽

Christian Baerlocher ◽

Dan Xie ◽

Stacey Zones ◽

...

Keyword(s):

Rietveld Refinement ◽

Poor Quality ◽

Data Sets ◽

Red Cell ◽

Structure Directing Agent ◽

Cell Parameters ◽

Combining Data ◽

Unit Cells ◽

High Silica ◽

High Degree

High-resolution synchrotron X-ray powder diffraction (SXPD) data alone are sometimes not enough to solve the structure of a complex polycrystalline material. Such was the case for the high-silica zeolites SSZ-61 and SSZ-87, where combining data from different sources, in particular XPD and electron microscopy, was vital to success. For SSZ-61, the SXPD data feature broad peaks and a resolution of ca. 1.2 Å. Although the pattern could be indexed, structure determination failed both with the charge flipping routine in SUPERFLIP [1] and with the zeolite-specific program FOCUS [2]. The unit cell parameters and HRTEM images indicated a relationship with ZSM-12 (MTW) and SSZ-59 (SFN), so several models derived from these two frameworks were built. Eventually, after considering Si-29 MAS NMR data and the size of the organic structure directing agent (SDA), a framework model that fits all the data emerged. To complete the structure, the SDA was included as a rigid-body, and its location and orientation optimized using simulated annealing. Subsequent Rietveld refinement confirmed the structure. In contrast to SSZ-61, the SXPD pattern for SSZ-87 was quite good, and it could be indexed with a C-centered cell. However, structure solution failed, probably because of the very high degree of reflection overlap (93%). Therefore, rotation electron diffraction (RED) data [3] were collected, but they proved to be of low resolution and poor quality. Only 2 of the 7 data sets could be indexed, and these had different unit cells. Neither fit the XPD pattern directly. The problem was traced to large errors in the RED cell parameters, and eventually one RED cell could be transformed to one similar to the SXPD cell. The RED data with this cell was only 15% complete up to a resolution of 1.22 Å. Even so, the structure could be solved using a recently developed version of FOCUS that works with ED data. The SDA was found as for SSZ-61, and the structure then confirmed by Rietveld refinement.

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