Dry gel conversion synthesis of shape controlled MFI type zeolite materials

Goergen, Simone; Saada, Mohamed Ali; Soulard, Michel; Rouleau, Loı̈c; Patarin, Joël

doi:10.1007/s10934-009-9333-0

Cited by 8 publications

(5 citation statements)

References 20 publications

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“…The XRD peaks in the pattern from these crystals are quite narrow; which shows that these crystals are large in accordance with SEM observations. However, it should be pointed out that these “large” crystals still are much smaller than previously reported for MFI zeolite grown using fluoride as mineralizing agent. − These “large” crystals are much smaller, probably since the concentration of silica in the synthesis mixture was higher than usual and the synthesis temperature was lower than usual in the present work. The (water + ethanol)/silica ratio in the synthesis mixture used in the present work was 12, while this ratio typically is between 30 and 80 in previously reported works. ,, Also, the synthesis was carried out at a temperature of 60 °C, while the temperature normally is between 120 and 200 °C. ,,, In the synthesis mixture used for preparation of the SCTPAF sample, ethanol was replaced by an equimolar amount of water and colloidal crystals were formed.…”

Section: Results and Discussionmentioning

confidence: 89%

Colloidal Defect-Free Silicalite-1 Single Crystals: Preparation, Structure Characterization, Adsorption, and Separation Properties for Alcohol/Water Mixtures

Zhou¹,

Mouzon²,

Farzaneh³

et al. 2015

Langmuir

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In this work, colloidal silicalite-1 single crystals are for the first time synthesized using fluoride as mineralizing agent at near neutral pH. SEM, TEM, DLS, XRD, solid-state (29)Si MAS NMR, and adsorption/desorption experiments using nitrogen, water, n-butanol, and ethanol as adsorbates were used to characterize the crystals. The single crystals have a platelike habit with a length of less than 170 nm and an aspect ratio (length/width) of about 1.2, and the thickness of the crystals is less than 40 nm. Compared with silicalite-1 crystals grown using hydroxide as mineralizing agent, the amount of structural defects in the lattice is significantly reduced and the hydrophobicity is increased. Membrane separation and adsorption results show that the synthesized defect-free crystals present high selectivity to alcohols from alcohol/water mixtures. The n-butanol/water adsorption selectivities were ca. 165 and 14 for the defect-free crystals and a reference sample containing defects, respectively, illustrating the improvement in n-butanol/water selectivity by eliminating the polar silanol defects.

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Section: Results and Discussionmentioning

confidence: 89%

Colloidal Defect-Free Silicalite-1 Single Crystals: Preparation, Structure Characterization, Adsorption, and Separation Properties for Alcohol/Water Mixtures

Zhou¹,

Mouzon²,

Farzaneh³

et al. 2015

Langmuir

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“…Several procedures have been developed for the shape control of zeolites: systematic variation of composition, pH, temperature, aging time and synthesis time; [10][11][12][13] use of inorganic cations; 14 templating using alkylammonium polycations; 15,16 use of different silicon precursors; 2,4,17 use of different alcohol additives and varying the water content and the Na 2 O/SiO 2 / Al 2 O 3 ratio as in the synthesis of large mordenite crystals. 7 Moreover, amorphous silica fibers coming from asbestos waste have been transformed by a dry gel conversion (DGC)-type synthesis into MFI-type zeolite fibers, 18 and MFI-type nanosheets have been made by using a diquaternary ammonium-type surfactant, long reaction time and a Na + -free silica source. 19,20 In a previous report 21 we followed the BMD method to crystallize silicalite-1 millimeter-sized crystals with a size of up to 3 mm.…”

Section: Introductionmentioning

confidence: 99%

Insight into the synthesis and characterization of zeolite millimeter-sized crystals

et al. 2012

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The effect of time, composition and structure-directing agents on the synthesis of silicalite-1 and octadecasil zeolite millimeter-sized crystals has been studied. Crystals up to about 3 mm size range were obtained and special attention was paid to their aspect ratio, thermal behavior, monocrystallinity and textural properties by means of electronic and optical microscopy, powder and single-crystal X-ray diffraction (XRD), thermogravimetry and Ar adsorption. For the silicalite-1 crystals obtained after 34 days of hydrothermal synthesis, more than one thousand specimens from two repeated batches were measured along a, b and c axes. Reproducibility was thus assessed simultaneously with a statistical analysis to obtain cumulative and differential distributions of crystal dimensions. Single-crystal XRD evidenced a high degree of monocrystallinity, while thermal analyses suggested that crystals with sizes above 125 mm have serious difficulties in activation, giving rise to high external specific surface area values upon Ar adsorption.

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“…Therefore, hierarchically macro-meso-microporous materials are expected to further enhance the mass transport and thus maximize the benefits of hierarchy in some catalyzed reactions 31 32 33 34 35 . As a type of unique morphology of material, zeolite fiber has attracted growing interest for a wide range of new applications in adsorption, optics, and chemical sensors 36 37 38 , etc. Specifically in catalysis, compared with the conventional zeolite powders, the structured zeolite fibers could provide fast diffusion and low pressure drop while maintaining the intrinsic high performance of zeolite 39 40 41 .…”

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confidence: 99%

Hierarchical Macro-meso-microporous ZSM-5 Zeolite Hollow Fibers With Highly Efficient Catalytic Cracking Capability

Liu

Jiang

Liu

et al. 2014

Sci Rep

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Zeolite fibers have attracted growing interest for a range of new applications because of their structural particularity while maintaining the intrinsic performances of the building blocks of zeolites. The fabrication of uniform zeolite fibers with tunable hierarchical porosity and further exploration of their catalytic potential are of great importance. Here, we present a versatile and facile method for the fabrication of hierarchical ZSM-5 zeolite fibers with macro-meso-microporosity by coaxial electrospinning. Due to the synergistic integration of the suitable acidity and the hierarchical porosity, high yield of propylene and excellent anti-coking stability were demonstrated on the as-prepared ZSM-5 hollow fibers in the catalytic cracking reaction of iso-butane. This work may also provide good model catalysts with uniform wall thickness and tunable porosity for studying a series of important catalytic reactions.

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Dry gel conversion synthesis of shape controlled MFI type zeolite materials

Cited by 8 publications

References 20 publications

Colloidal Defect-Free Silicalite-1 Single Crystals: Preparation, Structure Characterization, Adsorption, and Separation Properties for Alcohol/Water Mixtures

Colloidal Defect-Free Silicalite-1 Single Crystals: Preparation, Structure Characterization, Adsorption, and Separation Properties for Alcohol/Water Mixtures

Insight into the synthesis and characterization of zeolite millimeter-sized crystals

Hierarchical Macro-meso-microporous ZSM-5 Zeolite Hollow Fibers With Highly Efficient Catalytic Cracking Capability

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