Direct hydrothermal synthesis and stabilization of high-silica mordenite (Si∶Al = 25) using tetraethylammonium and fluoride ions

Sasaki, Hirokazu; Oumi, Yasunori; Itabashi, Keiji; Lu, Baowang; Teranishi, Toshiharu; Sano, Tsuneji

doi:10.1039/b212519f

Cited by 36 publications

(15 citation statements)

References 17 publications

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“…Different signals were grouped from 17°2theta to 68°2 theta where the most intense signal located at 30.9°2theta was referred to mordenite (JCPDS: O60239). This highest signal remained for any temperatures (25-700°C); however, the intensity was decreasing above 700°C until mineral disappearance at 900°C [16]. Similar behavior was noted for heulandite (JCPDS: 210131), it disappeared at 600°C due to structure collapses above 500°C [17,18].…”

Section: Results and Conclusionsupporting

confidence: 61%

Photo-Fenton Degradation of RB5 Dye in Aqueous Solution Using Fe Supported on Mexican Natural Zeolite

Domenzain-Gonzalez

Castro-Arellano

Galicia‐Luna

et al. 2019

International Journal of Photoenergy

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A Mexican natural zeolite (MNZ) was impregnated with Fe at concentrations of 5 and 10 mg FeCl3/g MNZ (MNZ/Fe) in order to study the photo-Fenton degradation of Reactive Black 5 (RB5) dye. Two samples were prepared and calcined at 550 and 700°C for each concentration. These samples were also characterized by the following techniques: X-ray diffraction (XRD) to determine crystalline phases of mineral, X-ray photoelectron spectroscopy (XPS) to observe the elemental composition of the material where the main element was Fe as Fe2p, Mössbauer to establish the phases in the material which were magnetite (Fe3O4), fayalite, and chlorite, Raman to corroborate that magnetite clusters in natural material were presented, and transmission electron microscopy (TEM) by which magnetite nanoparticles were observe on zeolite surface. Afterwards, the catalytic degradation of RB5 dye was performed by photo-Fenton process using a 2.2 W lamp as a radiation source. Four initial concentrations of RB5 dye ((RB5)0) were evaluated which ranged from 40 to 100 mg/L. Then, the evaluation reaction was carried out by UV-Vis spectroscopy to know the change in RB5 concentration and chemical oxygen demand (COD) removal to determine the organic carbon. The best results on the photo-Fenton degradation was 91% discoloration and 68.5% chemical oxygen demand removal based on an initial concentration RB50=100 mg/L and 10 mg MNZ/Fe (700°C of calcined temperature) at MNZ/Fe=0.05 g/L catalyst dose in aqueous solution, H2O2=3 g/L, pH=2.5, and 180 minutes of reaction time. Subsequently, variations on (RB5)0, pH, (H2O2), and (MNZ/Fe) were assessed in order to optimize the process by keeping 10 MNZ/Fe. The optimal RB5 dye degradation was achieved at RB50=100 mg/L in the presence of MNZ/Fe=0.2 g/L, H2O2=3 g/L and pH=2.5 where the highest discoloration and chemical oxygen demand removal were 93 and 70.5 at 180 min. Finally, the kinetic reaction was evaluated as a pseudo-first-order kinetics with an apparent rate constant (kapp) of 0.0225 min-1 at latest conditions.

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Section: Results and Conclusionsupporting

confidence: 61%

Photo-Fenton Degradation of RB5 Dye in Aqueous Solution Using Fe Supported on Mexican Natural Zeolite

Domenzain-Gonzalez

Castro-Arellano

Galicia‐Luna

et al. 2019

International Journal of Photoenergy

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“…Tetraethylammonium (TEA + ), a common OSDA, is among the simplest quaternary ammonium molecules, and its pore‐filling role is evident from the number of frameworks it is known to form: AEI, AFI, BEA, CHA, LTA, MFI, MOR, and UFI . TEA + is known to exist in two distinct conformations, designated as tt.tt and tg.tg , which can be easily distinguished using Raman spectroscopy, highlighted in Figure .…”

Section: Figurementioning

confidence: 90%

Template–Framework Interactions in Tetraethylammonium‐Directed Zeolite Synthesis

Schmidt

Deem

et al. 2016

Angewandte Chemie

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Zeolites,having widespread applications in chemical industries,are often synthesized using organic templates.These can be cost-prohibitive,motivating investigations into their role in promoting crystallization. Herein, the relationship between framework structure,c hemical composition, synthesis conditions and the conformation of the occluded, economical template tetraethylammonium (TEA + )has been systematically examined by experimental and computational means.T he results show two distinct regimes of occluded conformer tendencies:1 )Inf rameworks with al arge stabilization energy difference,o nly as ingle conformer was found (BEA, LTAa nd MFI). 2) In the frameworks with small stabilization energy differences (AEI, AFI, CHA and MOR), less than the interconversion of TEA + in solution, aheteroatom-dependent (Al, B, Co,M n, Ti,Z n) distribution of conformers was observed. These findings demonstrate that host-guest chemistry principles,i ncluding electrostatic interactions and coordination chemistry,are as important as ideal pore-filling.Microporous materials (MMs) are crystalline solids that contain pores of less than 2nm, and find applications ranging from separations and ion exchange to catalysis (zeolites are aluminosilicate MMs).[1, 2] Although over 230 frameworks are known, economic considerations,o fw hich the cost of the organic templates,r eferred to as organic structure-directing agents (OSDAs), dominate,m ean only ah andful are commercial, even though others could offer superior performance in agiven application. [3][4][5] This has inspired investigations into the complex processes governing the crystallization of MMs, with the goal of supplanting the use of expensive organics.

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“…We have studied the direct hydrothermal synthesis of high-silica MOR zeolite by various methods. Very recently, the highly crystalline MOR zeolite with a bulk Si/Al ratio of ≈ 30 was successfully prepared using both tetraethylammonium hydroxide as a structure-directing agent and NaF as a fluoride source, when Al(NO 3 ) 3 was employed as an aluminum source [22,23]. The addition of seed crystals or NH 4 NO 3 as a mineralizer was also found to be very effective for direct synthesis of high-silica MOR zeolite [24,25].…”

Section: Introductionmentioning

confidence: 99%

Aluminum distribution in high-silica mordenite

Kanai

Oumi

et al. 2006

J Porous Mater

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The Al distribution in high-silica MOR zeolites with various Si/Al ratios was investigated by FT-IR spectroscopy in the presence of CD 3 CN probe molecules and benzene adsorption. Two adsorption bands assigned to CN stretching vibration were observed at 2280-2295 and ≈ 2315 cm-1 , which are due to interaction of CN with acidic 1 hydroxyl groups in the main channels and the side pockets of H-MOR zeolite, respectively. The relative intensity of the peak at 2315 cm-1 increased with an increase in the Si/Al ratio, indicating that the proportion of Al atoms in the main channels relatively decreased with the Si/Al ratio. This was confirmed from the linear relationship between the number of benzene molecules adsorbed in a unit cell and the number of Al atoms in the main channels. In addition, this was also suggested from the computer simulation result that Al atoms are preferentially sitting in the T 3 site.

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Direct hydrothermal synthesis and stabilization of high-silica mordenite (Si∶Al = 25) using tetraethylammonium and fluoride ions

Cited by 36 publications

References 17 publications

Photo-Fenton Degradation of RB5 Dye in Aqueous Solution Using Fe Supported on Mexican Natural Zeolite

Photo-Fenton Degradation of RB5 Dye in Aqueous Solution Using Fe Supported on Mexican Natural Zeolite

Template–Framework Interactions in Tetraethylammonium‐Directed Zeolite Synthesis

Aluminum distribution in high-silica mordenite

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