Ultrafast Crystallization of AlPO₄-5 Molecular Sieve in a Deep Eutectic Solvent

Abstract

In the present work, ultrafast crystallization of AlPO 4 -5 molecular sieve was observed in a deep eutectic solvent (DES) composed of tetraethylammonium chloride (TEACl) and pentaerythritol (PE). Under conventional heating, the formation of AlPO 4 -5 can be as fast as a few minutes in the presence of F − at a reaction temperature as low as 150 °C. In the absence of F − , the nucleation of AlPO 4 -5 is delayed by approximately 30 min. Various characterization tools such as powder X-ray diffraction and ex situ or in situ multinuclear ( 1 H, 19 F, 14 N, 27 Al, 31 P, and 35 Cl) NMR were used to extract information on the structure of frozen DES, AlPO 4 -5 products, and solid and liquid phases of the reaction mixtures as a function of reaction time.Frozen DES is in a plastic phase at room temperature. An amorphous AlPOF phase appears to be an intermediate. Crystallization of AlPO 4 -5 without fluoride is also fast, but the nucleation is delayed by 30 min. The AlPO 4 -5 prepared in DES without fluoride has a crystal symmetry of P6cc, whereas crystallization in a fluoride medium produces AlPO 4 -5 with a lower crystal symmetry of Ccc2. This work demonstrates that in DES (TEACl and PE) AlPO 4 -based molecular sieves can be prepared within a very short time and at lower temperature and that the crystal symmetry of AlPO 4 -based molecular sieves can be controlled by addition of fluoride in this DES. The results also provide information that will assist researchers to gain a better understanding of how molecular sieves are formed in DES under ionothermal conditions.

Deep eutectic solvents for the preparation and post-synthetic modification of metal- and covalent organic frameworks

“…151 Those studies confirmed a peculiar crystal growth of MTN and MFI high-silica zeolites along with a higher local ordering around Si in DES with respect to conventional procedures. 150,151 In line with former studies dedicated to AlPOs synthesis by the groups of Morris 63,64 and Dong 105 and recently reinvestigated, 154 tetraalkylammonium halide/alcohol DESs acted as "smart" templates being able to produce either one metastable zeolite structure or shift towards another depending on the mineralizer nature, i.e. ; For OHanions.…”

“Removing Center”─An Effective Structure Design Strategy for Nonlinear Optical Crystals

“…After "removing center," the pore diameter becomes exponentially larger. So the "removing center" strategy can be used to explore macroporous materials, which can be used in the molecular sieve, 29 catalysis, 30 energy storage, 31 and so forth.…”

Insight in the Crystallization Kinetics of AlPO4-11 Molecular Sieve Using Di-Isopropylamine as Template

“…Several studies have been reported on the mechanism of crystallization of molecular sieves using dry gel and solid transformation method [12,13], synthesis of nanocrystal [14], ionothermal procedure [15] and membranes with distinctive porosities [16]. Recently, the synthesis of aluminophosphate using eutectic solvent [17] and non-hydrolytic sol-gel reactions [18] have been reported for preparation of high surface materials. However, many processes in hydrothermal crystallization are still not well understood.…”