Kinetics guided synthesis and performance of monodisperse zeolite LTA microspheres

Miao, Kanghua; Gao, Jinqiang; Zhang, Jian; Dong, Lei; Jia, Qiang; Wang, Rui-Qiang; Yu, Liwei; Wang, Shuangwei; Hong, Mei; Yang, Shihe

doi:10.1016/j.micromeso.2021.111194

Cited by 4 publications

(5 citation statements)

References 32 publications

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“…Although porous silica microspheres for fast chromatographic separation are rapidly developing with several kinds successfully prepared [20], converting them into corresponding zeolite microspheres has been, so far, unsuccessful. Our previous study [17], unfortunately, found a threshold silica microsphere diameter that limits the shape-reserving transformation into microspherical assemblies of NaA zeolite at around 3 µm. Under the previously selected crystallization conditions, larger cubic crystals with embedded macropores were obtained from porous silica microspheres smaller than 3 µm because the external gel network crystallization dominates below this threshold size value.…”

Section: Synthesis Of Downsized Sub-2-µm 4a Microspheresmentioning

confidence: 85%

“…They are also highly porous with a BET surface area of 263 m 2 /g and an average mesopore size of 8 nm. Although our previous SAC method [17] could afford zeolite spheres with a sizepreserved 0.5 mm diameter, their surface contained dents (Figure 5a). This suggests dominant local silica dissolution at the dent sites, unmatched by gel network formation.…”

Section: Synthesis Of Enlarged Sub-millimeter 4a Spheresmentioning

confidence: 92%

“…Spherical particles allow a smooth flow and are preferred for moving beds and packed columns [10]. In a previous study [17], we developed a shape-preserving steam-assisted crystallization (SAC) technique that transformed aluminum and sodium source-impregnated mesoporous silica microspheres into monodisperse zeolite LTA microspheres. The discovered control point for the shape preservation of mother spheres is balancing silica dissolution and zeolite nucleation.…”

Section: Introductionmentioning

confidence: 99%

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Spherical Binderless 4A/5A Zeolite Assemblies: Synthesis, Characterization, and Adsorbent Applications

Li,

Wang,

Gao

et al. 2024

Molecules

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Zeolite microspheres have been successfully applied in commercial-scale separators such as oxygen concentrators. However, further enhancement of their applications is hampered by the post-synthetic shaping process that formulates the zeolite powder into packing-sized spherical bodies with various binders leading to active site blockage and suboptimal performance. Herein, binderless zeolite microspheres with a tunable broad size range from 2 µm to 500 µm have been developed with high crystallinity, sphericity over 92%, monodispersity with a coefficient of variation (CV) less than 5%, and hierarchical pore architecture. Combining precursor impregnation and steam-assisted crystallization (SAC), mesoporous silica microspheres with a wide size range could be successfully transformed into zeolite. For preserved size and spherical morphology, a judicious selection of the synthesis conditions is crucial to ensure a pure phase, high crystallinity, and hierarchical architecture. For the sub-2-µm zeolite microsphere, low-temperature prolonged aging was important so as to suppress external zeolization that led to a large, single macroporous crystal. For the large 500 µm sphere, ultrasound pretreatment and vacuum impregnation were crucial and facilitated spatially uniform gel matrix dispersion and homogenous crystallization. The obtained zeolite 5A microspheres exhibited excellent air separation performance, while the 4A microspheres displayed ammonium removal capabilities. This work provides a general strategy to overcome the existing limitations in fabricating binder-free technical bodies of zeolites for various applications.

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Section: Synthesis Of Downsized Sub-2-µm 4a Microspheresmentioning

confidence: 85%

Section: Synthesis Of Enlarged Sub-millimeter 4a Spheresmentioning

confidence: 92%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Spherical Binderless 4A/5A Zeolite Assemblies: Synthesis, Characterization, and Adsorbent Applications

Li,

Wang,

Gao

et al. 2024

Molecules

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“…Commercial mesoporous silica microspheres were used as hard templates to synthesize zeolitic spheres for air separation. [56] Hao et al synthesized hierarchical mesoporous silica (NKM-5) using the polyelectrolyte surfactant templating method. [57] The mesoporous silica was used to load ceria and platinum NPs to increase catalytic surface area for combustion applications.…”

Section: Incorporated Isolated Metal Atomsmentioning

confidence: 99%

A comprehensive review on the synthesis techniques of porous materials for gas separation and catalysis

et al. 2022

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Intrinsic structural characteristics of porous materials have found significant applications in selective separation of gases and heterogeneous catalysis. While using porous materials for gas separation and catalysis, some of the challenging issues are the strength of catalytic sites, hydrothermal stability, crystalline order of solids, and selectivity. Researchers' ability to engineer the synthesis strategies rationally can help overcome technological challenges. In recent years, breakthroughs in porous materials are focused on developing different chemistries to control the pore architecture. This review focuses on recent advances made in synthesis strategies of porous materials and their impact on gas separation and catalysis applications. A significant part of this review is devoted to various synthesis methods, such as various types of templating methods, molecular layer deposition, sol-gel technique, and polymerization methods. Improvement in various catalytic reactions and gas separations due to different functionalization methods is also summarized. Lastly, we have discussed the applications of porous materials in the form of adsorbents and membranes in commercial processes. We hope that this review will serve as a quick reference for beginners who want to synthesize porous materials with control of pore structure.

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“…Many researchers have studied the hydrothermal synthesis of LTA zeolites, employing various techniques, such as using tetramethylammonium cations (TMA + ) as an organic structure-directing agent (OSDA), , adding fluoride anions, , or employing the charge-density mismatch (CDM) approach with two types of OSDAs, which resulted in the successful synthesis of highly crystalline LTA zeolites with various Si/Al ratios (1–∞). The crystallization mechanism and roles of OSDAs and fluoride anions have been investigated. − …”

Section: Introductionmentioning

confidence: 99%

Accelerated Crystallization of LTA Zeolite Using a Combination of High-Silica FAU Zeolite with Low Crystallinity and Additional Al Sources

Yoshida

Sada

Sano

et al. 2023

Crystal Growth & Design

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Synthesis methods and crystallization mechanisms of LTA zeolites have been studied by various approaches such as using alkali metal hydroxides, organic structure-directing agent cations, or fluoride anions, so that the understanding of the crystallization pathway is one of particular interest. As a fundamental research, we succeeded in synthesizing a highly crystalline LTA zeolite by combining dealuminated FAU with low crystallinity and an additional aluminum source (Al(OH) 3 ). The crystallization rate of the LTA zeolite was higher than that from conventional colloidal silica (Ludox HS-40) and Al(OH) 3 . In addition, there was a large difference in the particle size distribution of the as-made LTA zeolites. Furthermore, when using dealuminated FAU and Al(OH) 3 , Al-rich aluminosilicate species with four-ring structures were observed in the initial induction period, after which the gradual incorporation of TMA + cations into sod cages of the LTA zeolite was found. Based on the obtained results, a crystallization scheme for LTA zeolites synthesized using zeolitic sources of dealuminated FAU as starting materials is proposed, which deepens the understanding of the crystallization pathway of LTA zeolite.

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Kinetics guided synthesis and performance of monodisperse zeolite LTA microspheres

Cited by 4 publications

References 32 publications

Spherical Binderless 4A/5A Zeolite Assemblies: Synthesis, Characterization, and Adsorbent Applications

Spherical Binderless 4A/5A Zeolite Assemblies: Synthesis, Characterization, and Adsorbent Applications

A comprehensive review on the synthesis techniques of porous materials for gas separation and catalysis

Accelerated Crystallization of LTA Zeolite Using a Combination of High-Silica FAU Zeolite with Low Crystallinity and Additional Al Sources

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