Synthesis of FAU and EMT-type zeolites using structure-directing agents specifically designed by molecular modelling

Dhainaut, Jérémy; Daou, T. Jean; Chappaz, Alban; Bats, Nicolas; Harbuzaru, Bogdan; Lapisardi, G.; Chaumeil, Hélène; Defoin, Albert; Rouleau, Loı̈c; Patarin, Joël

doi:10.1016/j.micromeso.2013.03.006

Cited by 37 publications

(24 citation statements)

References 31 publications

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“…In addition to this, the platelets appear to have a uniform thickness as opposed to flattened edges as was seen in sample 1. The thickening of the platelets with reduced 18C6 suggests promoted growth along the [001] direction.Dhainaut et al[26] also observed thickening of the hexagonal platelets. When 1,4-di(azo-18-crown-6 ether)-butane (AC6-4) was used as OSDA to crystallise…”

mentioning

confidence: 90%

Systematic approaches towards template-free synthesis of EMT-type zeolites

Nearchou

Raithby

Sartbaeva

2018

Microporous and Mesoporous Materials

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Presently it is understood that 18-crown-6 ether is necessary as an organic template to synthesise pure and well crystalline EMT-type zeolites. This is problematic for optimisation of organic-free synthesis of zeolites. We report a new method to synthesise pure zeolite EMC-2 using a lower amount of 18-crown-6 ether than previously reported. At these low 18-crown-6 ether concentrations, FAU-type zeolites were not seen to co-crystallise. We observe that the crystallinity of the EMT-type zeolite is proportional to the amount of 18-crown-6 ether added in the synthesis. The as-synthesised zeolites were characterised using X-ray powder diffraction, scanning electron microscopy and solid state nuclear magnetic resonance. These findings are a crucial step towards understanding template roles and designing syntheses for zeolites without the use of toxic organic templates.

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mentioning

confidence: 90%

Systematic approaches towards template-free synthesis of EMT-type zeolites

Nearchou

Raithby

Sartbaeva

2018

Microporous and Mesoporous Materials

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“…EMT-type zeolite, EMC-2, for example is an extremely effective industrial catalyst for the alkylation of isobutane with 2-butene (Stocker et al, 1996;Rosenbach & Mota, 2005). A major ambition for the field is the development of 'designer' zeolites with tailored geometry for new catalytic applications, by the appropriate choice of synthesis conditions and organic structure-directing agents (oSDAs) whose shape is intended to template the specific pore geometry of the desired framework (Dhainaut et al, 2013). Efforts to predict hypothetical tetrahedral frameworks as candidate structures have led to an embarrassment of riches; for example, the symmetry constrained inter-site bonding search (SCIBS) and energy minimization approach of Treacy and Foster has generated a database that now exceeds 5 million types (Foster et al, 2005;Treacy et al, 2004).…”

Section: The Flexibility Window In Zeolitesmentioning

confidence: 99%

Intrinsic flexibility of porous materials; theory, modelling and the flexibility window of the EMT zeolite framework

Fletcher

Wells

Leung

et al. 2015

Acta Crystallogr Sect B

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Framework materials have structures containing strongly bonded polyhedral groups of atoms connected through their vertices. Typically the energy cost for variations of the inter-polyhedral geometry is much less than the cost of distortions of the polyhedra themselves -as in the case of silicates, where the geometry of the SiO 4 tetrahedral group is much more strongly constrained than the Si-O-Si bridging angle. As a result, framework materials frequently display intrinsic flexibility, and their dynamic and static properties are strongly influenced by low-energy collective motions of the polyhedra. Insight into these motions can be obtained in reciprocal space through the 'rigid unit mode' (RUM) model, and in real-space through template-based geometric simulations. We briefly review the framework flexibility phenomena in energy-relevant materials, including ionic conductors, perovskites and zeolites. In particular we examine the 'flexibility window' phenomenon in zeolites and present novel results on the flexibility window of the EMT framework, which shed light on the role of structure-directing agents. Our key finding is that the crown ether, despite its steric bulk, does not limit the geometric flexibility of the framework.

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“…There are many literature data documenting the synthesis of zeolite using both processes requiring organic compounds as structure-directing agents [ 1 , 2 , 3 , 4 , 5 ] and template-free synthesis with aluminate and silicate solutions [ 5 , 6 , 7 , 8 , 9 , 10 , 11 ]. However, all these processes have been performed through various methods, among which hydrothermal treatment [ 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 ] and ultrasonic irradiation [ 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 ] have been widely used.…”

Section: Introductionmentioning

confidence: 99%

Influence of Synthesis Method on LTA Time-Dependent Stability

2018

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Time-stability of LTA zeolite formed by hydrothermal method with or without the action of ultrasonic irradiation was investigated by X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM). The results show that 6 months after the synthesis by hydrothermal process with continuous sonication, LTA evolves into a more stable sodalite, whereas no differences are detected 12 months after LTA synthesis by conventional pre-fused hydrothermal process. These data confirm that using the two approaches, different mechanisms control both zeolite crystallization and time-stability of the newly-formed mineral at solid state. The results are particularly important in the light of the synthetic zeolite application.

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Synthesis of FAU and EMT-type zeolites using structure-directing agents specifically designed by molecular modelling

Cited by 37 publications

References 31 publications

Systematic approaches towards template-free synthesis of EMT-type zeolites

Systematic approaches towards template-free synthesis of EMT-type zeolites

Intrinsic flexibility of porous materials; theory, modelling and the flexibility window of the EMT zeolite framework

Influence of Synthesis Method on LTA Time-Dependent Stability

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