Synthesis of Zeolite Omega by the Magadiite Conversion Method and Insight into the Changes of Medium-Range Structure during Crystallization

Lv, Tianming; Zhang, Shoulei; Feng, Zhe Chuan; Wang, Fushi; Zhang, Shaoqing; Zheng, Jiqi; Liu, Xin; Meng, Changgong; Wang, Yu

doi:10.1021/acs.cgd.7b00571

Cited by 19 publications

(15 citation statements)

References 43 publications

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“…The magadiite exhibited a theoretical high cation exchange capacity (CEC) of nearly 200 meq/100 g [ 4 ], resulting in good ion exchange properties as a host for many organic and inorganic cations [ 5 , 6 , 7 , 8 , 9 , 10 , 11 ]. Magadiite was used as a silica precursor to prepare some new microporous zeolite materials with unique structures and properties using small organic templates [ 12 , 13 ]. The acidic properties of the magadiite could be enhanced by the insertion of other cations into the layered silicate, achieved during the synthesis by adding the cations precursors to the mixture of the silica source and NaOH.…”

Section: Introductionmentioning

confidence: 99%

Application of Organo-Magadiites for the Removal of Eosin Dye from Aqueous Solutions: Thermal Treatment and Regeneration

et al. 2018

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Na-magadiite exchanged with cetyl-trimethylammonium cations provided organophilic silicate materials that allowed for the effective removal of the acidic dye “eosin”. The organic cations were intercalated into the interlayer spacing of the layered silicate via an exchange reaction between the organic cations from their bromide salt and the solid Na-magadiite at room temperature. Different techniques were used to characterize the effect of the initial concentration of the surfactant on the structure of the organo-magadiites. The C, H, and N analysis indicated that a maximum of organic cations of 0.97 mmol/g was achieved and was accompanied by an expansion of the basal spacing of 3.08 nm, with a tilted angle of 59° to the silicate layers. The conformation of the organic surfactants was probed using solid-state 13C, finding mainly the trans conformation similar to that of the starting cetyl trimethylammonium bromide salt (C16TMABr). Thermal gravimetric analysis was carried out to study the thermal stability of the resulting organo-magadiites. The intercalated surfactants started to decompose at 200 °C, with a mass loss percentage of 8% to 25%, depending on the initial loading of the surfactant, and was accompanied by a decrease of the basal spacing from 3.16 nm to 2.51 nm, as deduced from the in situ X-ray diffraction studies. At temperatures below 220 °C, an expansion of the basal spacing from 3.15 to 3.34 nm occurred. These materials were used as a removal agent for the anionic dye eosin. The maximum amount of the dye removed was related to the organic cation content and to the initial concentration of eosin, with an improvement from 2.5 mg/g to 80.65 mg/g. This value decreased when the organo-magadiite was preheated at temperatures above 200 °C. The regeneration tests indicated that an 85% removal efficiency was maintained after six cycles of use for the organo-magadiite using Ci of 200 mg/L.

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Section: Introductionmentioning

confidence: 99%

Application of Organo-Magadiites for the Removal of Eosin Dye from Aqueous Solutions: Thermal Treatment and Regeneration

et al. 2018

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“…4(C) shows the solid-state 27 Al NMR spectrum of the as-synthesized and calcined MAZ-180 samples comprising two obvious signals at ~60 and ~55 ppm, which can be assigned to the two T-sites in the MAZ framework [34]. In addition, we cannot observe a signal at 0 ppm associated with the extra framework of the Al species in the zeolite framework [35]. Figs.…”

Section: Resultsmentioning

confidence: 92%

Design of fast crystallization of nanosized zeolite omega crystals at higher temperatures

Zhang

Yang

et al. 2019

Chinese Journal of Catalysis

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Fast crystallization of nanosized zeolite crystals is a very popular process used for practical zeolite catalyst applications. Herein, we report a designer crystallization process for nanosized zeolite omega crystals based on the relationship between the crystallization time and temperature in the Arrhenius equation. Compared to the conventional hydrothermal synthesis of zeolite omega (72 h at room temperature and 240 h at 100 C, MAZ-100), the crystallization of zeolite omega presented in this work only requires a very short time interval (5 h at 180 C, MAZ-180). Physicochemical characterizations, including XRD, SEM, N2 sorption isotherms, and 27 Al MAS NMR show that the product of zeolite omega (MAZ-180) has good crystallinity and uniform nanocrystals. More importantly, after the loading of Pt nanoparticles (0.5 wt%), the Pt/H-MAZ-180 catalyst exhibits higher isomer selectivity and lower cracking selectivity than those of the Pt/H-MAZ-100 catalyst in the hydroisomerization of n-dodecane. These results suggest the potential applications of these omega nanocrystals as supporting catalyst compounds in industrial processes.

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“…Preparation of Zeolite Omega Seed Crystals. Omega seeds used in this work were prepared from the hydrothermal transformation of magadiite in the presence of tetramethylammonium bromide (TMABr) as we have reported: 15 with a chemical composition of 20 SiO 2 :Al 2 O 3 :3.6 Na 2 O:180 H 2 O:0.96 TMABr, pure zeolite omega can be synthesized from a suspension after hydrothermal heating at 100 °C for 72 h. After centrifugation and washing with deionized water until neutrality, the final solid product was dried at 50 °C overnight. The obtained zeolite omega samples were calcined at 550 °C for 10 h to get rid of TMA + in their channels before being used as seeds.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

“…According to our previous reports, a glycerol−water system was suitable for the synthesis of pure zeolite omega by the conversion of magadiite, 14 and TMA + can also drive the preparation of zeolite omega from magadiite conversion under hydrothermal conditions. 15 Simultaneously, to get better insights into the conversion mechanism, the changes of a medium-range structure in the conversion course were discussed in detail to rationalize the conversion process. 14−16 However, the conventional hydrothermal synthesis method has obvious the following disadvantages: (1) the use of water solvent leads to the consumption of partial aluminosilicate nutrients, which leads to low-efficiency synthesis.…”

Section: ■ Introductionmentioning

confidence: 99%

Solid-State and Organic Template-Free Synthesis of Zeolite Omega by Conversion of Magadiite in the Presence of Seed Crystals and Investigation of Conversion Mechanism

Zhang

Feng

et al. 2020

Ind. Eng. Chem. Res.

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In this work, we developed a sustainable synthesis of zeolite omega via the conversion of magadiite under solid-state and organic template-free conditions. The conversion behavior and mechanism were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy, Raman spectroscopy, and 27 Al magic-angle spinning nuclear magnetic resonance (MAS NMR) in detail. It can be found that most of the 5Rs and part of 6Rs in magadiite were maintained as mediumrange structures to participate in the formation of zeolite omega; additive seed crystals underwent destruction due to collapse of the four-membered rings and five-membered rings in the MAZ framework, while the remaining six-membered rings from seed crystals acted as the secondary crystal nucleus to provide direction function; Al species preferred to enter T2 positions, which are located in the sixmembered rings in zeolite omega. In addition, the influences of synthesis parameters were discussed in detail.

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Synthesis of Zeolite Omega by the Magadiite Conversion Method and Insight into the Changes of Medium-Range Structure during Crystallization

Cited by 19 publications

References 43 publications

Application of Organo-Magadiites for the Removal of Eosin Dye from Aqueous Solutions: Thermal Treatment and Regeneration

Application of Organo-Magadiites for the Removal of Eosin Dye from Aqueous Solutions: Thermal Treatment and Regeneration

Design of fast crystallization of nanosized zeolite omega crystals at higher temperatures

Solid-State and Organic Template-Free Synthesis of Zeolite Omega by Conversion of Magadiite in the Presence of Seed Crystals and Investigation of Conversion Mechanism

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