A top-down methodology for ultrafast tuning of nanosized zeolites

Liu, Zhendong; Nomura, Naoki; Nishioka, Daisuke; Hotta, Yuusuke; Matsuo, Tetsuji; Oshima, Kazunori; Yanaba, Yutaka; Yoshikawa, Takeshi; Ohara, Koji; Kohara, Shinji; Takewaki, Takahiko; Okubo, Tatsuya; Wakihara, Toru

doi:10.1039/c5cc04542h

Cited by 52 publications

(22 citation statements)

References 33 publications

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“…However, the sole presence of relatively small micropores in SSZ‐13 zeolites strongly inhibits the diffusion of reactants and products, especially for bulky molecules. One strategy to overcome this drawback is to decrease the size of zeolite crystals, which can offer a shorter diffusion path as well as more exposed active sites on the external surface . However, the difficult manipulation of nanosized zeolite particles is a pending obstacle in practical applications .…”

Section: Introductionmentioning

confidence: 99%

Template‐Free Synthesis of Hierarchical SSZ‐13 Microspheres with High MTO Catalytic Activity

Bing

Tian

Wang

et al. 2018

Chemistry A European J

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Hierarchical SSZ-13 microspheres, with abundant mesoporous channels, have been successfully synthesized by addition of calcined SSZ-13 crystals in the starting gel in the absence of any organic templates. This strategy not only remarkably reduces the production cost and environmental pollution, but also significantly decreases the crystallization time as well as evidently reducing the zeolite crystal sizes in many cases. The synthesized sample was characterized by XRD, BET, ICP, SEM, TEM, TG, and NH -TPD, which indicates that the organic template free synthesized SSZ-13 exhibits high crystallinity, textural properties, and acidity. Moreover, the synthesized hierarchical SSZ-13 catalyst shows outstanding performance in the methanol-to-olefin (MTO) reaction, with slightly higher ethylene plus propylene selectivity and prolonged catalyst lifetime as compared to the templated SSZ-13 catalyst.

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Section: Introductionmentioning

confidence: 99%

Template‐Free Synthesis of Hierarchical SSZ‐13 Microspheres with High MTO Catalytic Activity

Bing

Tian

Wang

et al. 2018

Chemistry A European J

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“…Here, we report on the preparation of very small and well‐defined, colloidal nanocrystals using straightforward conventional methods in fluoride media. Approaches for synthesis of nanosized zeolite can be classified into two distinct categories: 1) bottom‐up, by engineering of the crystallization process, such as controlling the kinetics of nucleation versus crystal growth, introducing organic additives or confined‐space synthesis; 2) top‐down, that is, post‐treatment using mechanical force to break large zeolite crystals into nanosized units, the disadvantages of this method, like partial amorphization and broader particle size distribution, can be remedied by recrystallization . Here, we adopted the two approaches and successfully synthesized 10 nm thick pure silica MFI crystals through the bottom‐up approach and 100 nm pure silica CHA crystals by the top‐down approach.…”

Section: Figurementioning

confidence: 99%

Facile Preparation of Hydrophobic Colloidal MFI and CHA Crystals and Oriented Ultrathin Films

Zhou

Hedlund

2018

Angewandte Chemie

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We report novel routes for synthesis of defect-free, hydrophobic and monodispersed 10 nm (5 unit cells) thick MFI crystals and 100 nm CHA crystals.T he crystals are obtained in high yield and displayv ery high 1-butanol adsorption from aqueous solution. These crystals are assembled in monolayers for the growth of ultrathin and uniformly oriented films with thicknesses of 36 nm and 330 nm, respectively,u sing as ynthesis gel in the form of ap owder.T his method is very simple and may open up for industrial preparation of materials with improved performances.Increasing efforts have been devoted to synthesizing zeolites with enhanced accessibility to their micropores. [1,2] The particle size reduction of zeolites to the nanometer scale leads to significant changes in properties such as increased external surface areas and decreased diffusion path lengths and the possibility to use for preparation of ultrathin films. However,t he synthesis of nanosized zeolites in hydroxide media brings less desired properties of silanol groups as surface defects.The synthesis of zeolites in fluoride media was developed to alleviate these problems by preparing silanolfree zeolites.H owever,t he zeolite crystals harvested in fluoride media usually have as ize of several micrometers. Consequently,t here is an eed to produce silanol-free zeolite crystals with nanometer size.Here,wereport on the preparation of very small and welldefined, colloidal nanocrystals using straightforward conventional methods in fluoride media. Approaches for synthesis of nanosized zeolite can be classified into two distinct categories:1 )b ottom-up,b ye ngineering of the crystallization process,s uch as controlling the kinetics of nucleation versus crystal growth, [3,4] introducing organic additives [5] or confinedspace synthesis; [6] 2) top-down, that is,p ost-treatment using mechanical force to break large zeolite crystals into nanosized units,t he disadvantages of this method, like partial amorphization and broader particle size distribution, can be remedied by recrystallization. [7,8] Here,weadopted the two approaches and successfully synthesized 10 nm thick pure silica MFI crystals through the bottom-up approach and 100 nm pure silica CHA crystals by the top-down approach. Them ono-dispersed and silanol-free crystals prepared in the present work are the smallest ever reported.The10nmthick MFI crystals are comparable to the 5nm (2.5 unit cells) thick nanosheets produced by seeded growth in hydroxide (OH À )m edia with an on-commercially available template. [9] Our defect-free,h ydrophobic MFI crystals produced in fluoride medium displays very high adsorption capacity of 1-butanol (0.13 gg À1 zeolite) from aw ater solution, equal to the equilibrium adsorption ability estimated by Monte Carlo simulations. [10] The1 00 nm CHA crystal shows very high 1-butanol adsorption (0.18 gg À1 zeolite) from aqueous solution, which is two times higher than the reported adsorption of micrometer sized Si-CHA crystals from vaporphase. [11] Furthermore,t he MFI crystals are o...

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“…Thus, in this case, seed crystals after the milling worked as the source of units. It is known that zeolites after a mechanochemi‐cal treatment have defects that accelerate recrystallization of zeolites . Therefore, in our synthesis method, units of zeolite could be formed by the ball milling and uniformly dis‐persed in the aluminosilicate composite, which would contrib‐ute to the crystallization of ZSM‐5.…”

Section: Figurementioning

confidence: 99%

Solvent- and OSDA-Free Synthesis of ZSM-5 Assisted by Mechanochemical and Vapor Treatments

et al. 2017

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Various synthesis methods of zeolites have been established. Hydrothermal synthesis method with organic structure directing agent (OSDA) has been widely applied in zeolite synthesis. However, this method has some big problems in terms of industrial and environmental aspects: OSDA is expensive and thermally decomposed OSDA produces air pollution; and the yield of zeolite crystals per reactor volume is low due to the presence of solvent. We hence synthesized ZSM‐5 (MFI‐type zeolite) in the absence of both solvent and OSDA to overcome these problems. Briefly, the starting materials including silica powder, sodium aluminate, sodium hydroxide and a small amount of seed crystals (ZSM‐5) were mixed together and grinded using a ball mill. Then the milled powder was crystallized under a steam atmosphere by varying crystallization time. We found that an MFI phase started to appear after 12 h and the formation of pure ZSM‐5 crystals was completed after 24 h. Our method provides a simpler and efficient process of zeolite synthesis in an environment‐friendly manner than those of any conventional solvent methods, which will promise to promote mass production of a variety of zeolites.

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A top-down methodology for ultrafast tuning of nanosized zeolites

Cited by 52 publications

References 33 publications

Template‐Free Synthesis of Hierarchical SSZ‐13 Microspheres with High MTO Catalytic Activity

Template‐Free Synthesis of Hierarchical SSZ‐13 Microspheres with High MTO Catalytic Activity

Facile Preparation of Hydrophobic Colloidal MFI and CHA Crystals and Oriented Ultrathin Films

Solvent- and OSDA-Free Synthesis of ZSM-5 Assisted by Mechanochemical and Vapor Treatments

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