Crystallization, stability and possible application of the molecular sieve cloverite

Fricke, R.; Zubowa, Heide-Lore; Richter, M.; Kosslick, H.

doi:10.1016/j.crci.2004.09.010

Cited by 10 publications

(6 citation statements)

References 27 publications

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“…The notable examples include Mu-n, [9][10][11] ULM-n, [12][13][14][15] MIL-n, 16,17 DIPYR-GaPO 18 and in particular, cloverite with extra large pores. [19][20][21][22][23] Synthesis of open-framework inorganic gallophosphates is similar to zeolites and aluminophosphates. Solid and liquid reagents together with an organic amine as a structure-directing agent (SDA) are combined with a solvent (usually water), yielding a reactive gel from which a gallophosphate crystallizes under hydrothermal conditions.…”

Section: Introductionmentioning

confidence: 99%

Characterization of the gel phases formed in the synthesis of microporous gallophosphate, cloverite

2010

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Section: Introductionmentioning

confidence: 99%

Characterization of the gel phases formed in the synthesis of microporous gallophosphate, cloverite

2010

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“…Finally, several phosphate‐based zeotypes with d4r cages have been synthesised in fluoride‐containing media, among them the extra‐large pore gallophosphate (GaPO) cloverite (−CLO) [35] and LTA‐type aluminophosphates (AlPOs) [36,37] . While practical applications of cloverite are severely limited due to its low stability, [38] AlPO 4 ‐LTA has been employed in membrane‐based separations [39] and in thermal energy storage [40,41] …”

Section: Introductionmentioning

confidence: 99%

Local Distortions in a Prototypical Zeolite Framework Containing Double Four‐Ring Cages: The Role of Framework Composition and Organic Guests**

Fischer

Freymann

2020

ChemPhysChem

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Cube‐like double four‐ring ( d4r ) cages are among the most frequent building units of zeolites and zeotypes. In materials synthesised in fluoride‐containing media, the fluoride anions are preferentially incorporated in these cages. In order to study the impact of framework composition and organic structure‐directing agents (OSDAs) on the possible occurrence of local distortions of fluoride‐containing d4r cages, density functional theory (DFT) calculations and DFT‐based molecular dynamics simulations were performed for AST‐type zeotypes, considering four different compositions (SiO 2 , GeO 2 , AlPO 4 , GaPO 4 ) and two different OSDA cations (tetramethylammonium [TMA] and quinuclidinium [QNU]). All systems except SiO 2 ‐AST show significant deformations, with a pyritohedron‐like distortion of the d4r cages occurring in GeO 2 ‐ and GaPO 4 ‐AST, and a displacement of the fluoride anions towards one of the corners of the cage in AlPO 4 ‐ and GaPO 4 ‐AST. While the distortions occur at random in TMA‐containing zeotypes, they exhibit a preferential orientation in systems that incorporate QNU cations. In addition to providing detailed understanding of the local structure of a complex host‐guest system on the picosecond timescale, this work indicates the possibility to stabilise ordered distortions through a judicious choice of the OSDA, which might enable a tuning of the material's properties.

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“…23,32 Finally, several phosphate-based zeotypes with d4r cages have been synthesised in fluoride-containing media, among them the extra-large pore gallophosphate (GaPO) cloverite (-CLO) 33 and LTA-type aluminophosphates (AlPOs). 34,35 While practical applications of cloverite are severely limited due to its low stability, 36 AlPO4-LTA has been employed in membrane-based separations 37 and in thermal energy storage. 38 X-ray diffraction investigations of as-synthesised samples prepared via the "fluoride route" have typically located the fluoride anions at, or close to, the centre of the d4r cage in all-silica zeolites like octadecasil, 9,39 ITQ-7, 40 ITQ-12, 11 and ITQ-13, 12 and in GeO2 zeotypes like ASU-7 (ASV), 41,42 ASU-9 (AST), [41][42][43] FOS-5 (BEC), 44 ITQ-21, 45 and IM-10 (UOZ).…”

Section: Introductionmentioning

confidence: 99%

Local Distortions in a Prototypical Zeolite Framework Containing Double Four-Ring Cages: The Role of Framework Composition and Organic Guests

Fischer¹,

Freymann²

2020

Preprint

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Cube-like double four-ring (d4r) cages are among the most frequent building units of zeolites and zeotypes. In materials synthesised in fluoride-containing media, the fluoride anions are preferentially incorporated in these cages. In order to study the impact of framework composition and organic structure-directing agents (OSDAs) on the possible occurrence of local distortions of fluoride-containing d4r cages, density functional theory (DFT) calculations and DFT-based molecular dynamics simulations were performed for AST-type zeotypes, considering four different compositions (SiO2, GeO2, AlPO4, GaPO4) and two different OSDA cations (tetramethylammonium [TMA] and quinuclidinium [QNU]). All systems except SiO2-AST show significant deformations, with a pyritohedron-like distortion of the d4r cages occurring in GeO2- and GaPO4-AST, and a displacement of the fluoride anions towards one of the corners of the cage in AlPO4- and GaPO4-AST. While the distortions occur at random in TMA-containing zeotypes, they exhibit a preferential orientation in systems that incorporate QNU cations. In addition to providing detailed understanding of the local structure of a complex host-guest system on the picosecond timescale, this work indicates the possibility to stabilise ordered distortions through a judicious choice of the OSDA, which might enable a tuning of the material’s properties.

show abstract

Crystallization, stability and possible application of the molecular sieve cloverite

Cited by 10 publications

References 27 publications

Characterization of the gel phases formed in the synthesis of microporous gallophosphate, cloverite

Characterization of the gel phases formed in the synthesis of microporous gallophosphate, cloverite

Local Distortions in a Prototypical Zeolite Framework Containing Double Four‐Ring Cages: The Role of Framework Composition and Organic Guests**

Local Distortions in a Prototypical Zeolite Framework Containing Double Four-Ring Cages: The Role of Framework Composition and Organic Guests

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