A Rational Approach to the Ionothermal Synthesis of an AlPO₄ Molecular Sieve with an LTA‐Type Framework

Abstract

Structurally sound: The synthesis of AlPO4‐LTA zeolite in ionic liquids employs 1‐benzyl‐3‐methylimidazolium, tetramethylammonium, and fluoride ions for structuring α cages, sodalite cages, and cubes (see picture; C gray, N blue, O red, Al and P purple, F green). Selective removal of 1‐benzyl‐3‐methylimidazolium ions results in a stable AlPO4‐LTA molecular sieve. The α cages of AlPO4‐LTA framework can be evacuated while maintaining structural integrity.

Co‐Structure‐Directing Effect in Ionothermal Synthesis of Extra‐Large‐Pore Aluminophosphate Zeotype with −CLO Topology

“…Half of the d4r units are not fully connected with two terminal hydroxy groups in each unit, which extend into the 20-ring openings. [27][28][29][30][31] Tian and co-workers found that the addition of organic amines to 1-butyl-3-methyl imidazolium IL could affect the kineticso ft he crystallization process, resulting in the formation of aluminophosphate zeotypes with AEL, AFI, and LTA topologies, depending on the concentration of organic amines. Although the germanium silicate analogue was prepared by using the diisopropylethylmethyl ammonium cation as the SDA, the gallium phosphate analoguew as first synthesized by using quinuclidinea st he SDA and alternativelyp repared by means of an ionothermal methodw ith the ionic liquid (IL) 1ethyl-3-methylimidazolium bromide ([EMIM]Br) as both solvent and SDA.…”

Ionothermal Synthesis of Molecular Sieves

“…The in situ XRD patterns of DNL-1 show that no significant loss of crystallinity occurs until the temperature reaches approximately 950 °C. Moreover, the ordered crystalline structure of DNL-1 can remain after calcination at 850 °C and subsequent exposure at room temperature with 60 % humidity for 6 d. 1-Benzyl-3-methylimidazolium chloride Al + P (None) [70] (continued) Choline chloride-2-imidazolidone Co + P (None) [55] Choline chloride-2-imidazolidone Zn + P (None) [83] (continued) Only the formally published results are included. In some cases, the products contain more than one crystalline phase…”

“…Based on Rietveld refinement and NMR spectroscopy, Fayad et al suggested that the structure-directing agents 1-benzyl-3-methylimidazolium cations, tetramethylammonium cations and fluoride anions fill in the lta cages, sod cages and d4r units of AlPO-LTA respectively ( Fig. 2.10) [70]. In the structure of DNL-1, it was found that 1,6-hexanediamine molecules prefer to fill in the lta cages with random orientation, while EMIm cations present in both the lta cages and the empty space at the intersection of the 20-membered ring channels [106].…”

“…Structure analysis of the ionothermally synthesized AlPO-LTA [70] and DNL-1 [81,106] shows an interesting cooperating mode of multiple structure-directing agents with significantly different shapes and sizes. Based on Rietveld refinement and NMR spectroscopy, Fayad et al suggested that the structure-directing agents 1-benzyl-3-methylimidazolium cations, tetramethylammonium cations and fluoride anions fill in the lta cages, sod cages and d4r units of AlPO-LTA respectively ( Fig.…”

Synthesis and characterization of DNL-6, a new silicoaluminophosphate molecular sieve with the RHO framework

“…However, rational design of novel materials with targeted properties (structure, composition, morphology, etc.) still remains a challenge, although some evident progress has been made by several research teams [4][5][6][7].…”