Facile Synthesis of Hierarchical Nanosized Single‐Crystal Aluminophosphate Molecular Sieves from Highly Homogeneous and Concentrated Precursors

Tao, Shuo; Li, Xiaolei; Wang, Xiaoge; Wei, Ying; Jia, Ya; Ju, Jing; Cheng, Yuanhui; Wang, Huaisheng; Gong, Shuwen; Yao, Xueping; Gao, Haixu; Zhang, Cunyin; Zang, Qiqi; Tian, Zhijian

doi:10.1002/anie.201915144

Cited by 43 publications

(24 citation statements)

References 36 publications

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“…The embedded P407 was probably present at the gaps between the primary CyA nanoglasses as a result of entrapment by aggregation of the primary CyA nanoglasses. Aggregates of small amorphous particles have been observed in inorganic compounds and proteins. − Both the small particle size and the disordered packing of molecules in amorphous materials result in a high-energy state of the particle surface . Thus, the CyA nanoglasses in the present study had a high tendency of aggregation to minimize the surface free energy despite the presence of many P407 micelles.…”

Section: Resultsmentioning

confidence: 66%

Transition from Amorphous Cyclosporin A Nanoparticles to Size-Reduced Stable Nanocrystals in a Poloxamer 407 Solution

et al. 2021

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Amorphous drug nanoparticles usually exhibit low storage stability. A comprehensive understanding of the molecular states and physicochemical properties of the product is indispensable for designing stable formulations. In the present study, an amorphous cyclosporin A (CyA) nanosuspension with a mean particle size of approximately 370 nm was prepared by wet bead milling with poloxamer 407 (P407). Interestingly, the prepared amorphous CyA nanoparticles were transformed into uniform CyA nanocrystals with a reduced mean particle size of approximately 200 nm during storage at 25 °C. The CyA nanocrystals were stably maintained for at least 1 month. The particle morphologies and molecular structures of the CyA nanosuspensions before and after storage were thoroughly characterized by cryogenic transmission electron microscopy and magic-angle spinning nuclear magnetic resonance spectroscopy, respectively. They revealed that the freshly prepared amorphous CyA nanoparticles (∼370 nm) were secondary particles composed of aggregated primary particles with an estimated size of 50 nm. A portion of P407 was found to be entrapped at the gaps between the primary particles due to aggregation, while most of P407 was dissolved in the solution either adsorbing at the solid/liquid interface or forming polymeric micelles. The entrapped P407 is considered to play an important role in the destabilization of the amorphous CyA nanoparticles. The resultant CyA nanocrystals (∼200 nm) were uniform single crystals of Form 2 hydrate and showed corner-truncated bipyramidal features. Owing to the narrow particle size distribution of the CyA nanocrystals, the rate of Ostwald ripening was slow, giving long-term stability to the CyA nanocrystals. This study provides new insights into the destabilization mechanism of amorphous drug nanoparticles.

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Section: Resultsmentioning

confidence: 66%

Transition from Amorphous Cyclosporin A Nanoparticles to Size-Reduced Stable Nanocrystals in a Poloxamer 407 Solution

et al. 2021

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“…It should be noted that the sharp increase of adsorption amounts at p/p 0 >0.95 were due to the interparticle pores between 200–300 nm sized zeolites. The gentle slope at the range of p/p 0 = 0.4‐0.9 was attributed to the intraparticle mesopores . More importantly, the introduction of the mesopores did not decrease the microporous volume (Table S1).…”

Section: Figurementioning

confidence: 95%

A Single‐Crystalline Hierarchical Zeolite via an Oriented Co‐Growth of Nanocrystals Based on Synergy of Polyelectrolytes and Hetero‐Atoms

et al. 2020

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Hierarchical zeolites have attracted great attention due to the integration of mesopores and/or macropores into the microporous crystalline framework, which decreases the steric and diffusional limitations in the small-size micropores of zeolites. Among them, single-crystalline hierarchical zeolites are much desirable due to fewer crystalline defects, higher mechanical stability, and less blocking of the uniform direction of microporous channels, which show high catalytic performance in conventional industrially-important small-molecule reactions, and heavy-oil catalytic cracking, biomass catalytic conversion, polymer degradation, etc. Here, a novel one-pot kineticsdominated strategy was developed to synthesize titaniumcontaining single-crystalline hierarchical zeolites via synergy of polyelectrolytes and framework hetero-atoms by means of concentrating the starting precursor, restriction of the Oswald ripening to protect nano-crystals, as well as oriented attachment between nano-crystals. The resultant zeolite displayed a much higher catalytic performance in olefin epoxidation and cyclohexanone ammoximation than those of conventional pure-microporous zeolites.Zeolites are microporous crystalline solid materials with high surface area and high thermal/hydrothermal stability, which are widely used as solid catalysts in refining and petrochemical processes. [1] The intrinsic micropores (< 2.0 nm) at the level of molecular size gave zeolites remarkable catalytic properties over other catalysts, especially their unique shape-selectivity. [2] [a] Y.

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“…The concentration of the zeolite synthesis gels greatly influences the final morphologies of the product. − The concentrated reaction mixtures resulted in the generation of mesoporous aggregates of Beta zeolite nanocrystals, while the diluted ones led to isolated zeolite nanocrystals . Thus, the dry-gel conversion process, with a highly concentrated zeolite precursor for promoting nucleation, was found to be a useful way to construct a hierarchical structure aggregated by zeolite nanocrystals.…”

Section: Synthesismentioning

confidence: 99%

Hierarchically Structured Zeolites: From Design to Application

et al. 2020

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Hierarchical zeolites combine the intrinsic catalytic properties of microporous zeolites and the enhanced access and transport of the additional meso-and/or macroporous system. These materials are the most desirable catalysts and sorbents for industry and become a highly evolving field of important current interests. In addition to the enhanced mass transfer leading to high activity, selectivity, and cycle time, another essential merit of the hierarchical structure in zeolite materials is that it can significantly improve the utilization effectiveness of zeolite materials resulting in the minimum energy, time, and raw materials consumption. Substantial progress has been made in the synthesis, characterization, and application of hierarchical zeolites. Herein, we provide an overview of recent achievements in the field, highlighting the significant progress in the past decade on the development of novel and remarkable strategies to create an additional pore system in zeolites. The most innovative synthesis approaches are reviewed according to the principle, versatility, effectiveness, and degree of reality while establishing a firm link between the preparation route and the resultant hierarchical pore quality in zeolites. Zeolites with different hierarchically porous structures, i.e., micro-mesoporous structure, micromacroporous structure, and micro-meso-macroporous structure, are then analyzed in detail with concrete examples to illustrate their benefits and their fabrications. The significantly improved performances in catalytic, environmental, and biological applications resulting from enhanced mass transport properties are discussed through a series of representative cases. In the concluding part, we envision the emergence of "material-properties-by-quantitative and real rational design" based on the "generalized Murray's Law" that enables the predictable and controlled productions of bioinspired hierarchically structured zeolites. This Review is expected to attract important interests from catalysis, separation, environment, advanced materials, and chemical engineering fields as well as biomedicine for artificial organ and drug delivery systems.

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Facile Synthesis of Hierarchical Nanosized Single‐Crystal Aluminophosphate Molecular Sieves from Highly Homogeneous and Concentrated Precursors

Cited by 43 publications

References 36 publications

Transition from Amorphous Cyclosporin A Nanoparticles to Size-Reduced Stable Nanocrystals in a Poloxamer 407 Solution

Transition from Amorphous Cyclosporin A Nanoparticles to Size-Reduced Stable Nanocrystals in a Poloxamer 407 Solution

A Single‐Crystalline Hierarchical Zeolite via an Oriented Co‐Growth of Nanocrystals Based on Synergy of Polyelectrolytes and Hetero‐Atoms

Hierarchically Structured Zeolites: From Design to Application

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