Super-ions of sodium cations with hydrated hydroxide anions: inorganic structure-directing agents in zeolite synthesis

Asselman, Karel; Pellens, Nick; Radhakrishnan, Sambhu; Chandran, C. Vinod; Martens, Johan A.; Taulèlle, Francis; Verstraelen, Toon; Hellström, Matti; Breynaert, Eric; Kirschhock, Christine

doi:10.1039/d1mh00733e

Cited by 19 publications

(41 citation statements)

References 36 publications

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“…In analogy, concentrated NaOH mixtures wherein hydroxysodalite crystallizes ( Figure 2 ), a clear correspondence exists between the coordination assemblies of sodium clusters in the synthesis liquid and within the sodalite cages after crystallization. 4 Therefore, it can be suggested that zeolite polymorphism is, similar to zeolite composition, a direct result of the chemical state of the synthesis liquid prior to nucleation.…”

Section: Discussionmentioning

confidence: 99%

“… 4 This complexity explains why even small variations of composition and conditions may turn synthesis to vastly different products. 4 − 8 Besides the framework topology, zeolite properties are determined by their composition, 9 characterized for aluminosilicate zeolites by the Si/Al ratio and extra-framework species. Lechert and co-workers 10 − 13 were first to empirically establish quantitative correlations between zeolite aluminum content and alkalinity of the liquid phase.…”

Section: Introductionmentioning

confidence: 99%

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Ion-Pairs in Aluminosilicate-Alkali Synthesis Liquids Determine the Aluminum Content and Topology of Crystallizing Zeolites

et al. 2022

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Using hydrated silicate ionic liquids, phase selection and framework silicon-to-aluminum ratio during inorganic zeolite synthesis were studied as a function of batch composition. Consisting of homogeneous single phasic liquids, this synthesis concept allows careful control of crystallization parameters and evaluation of yield and sample homogeneity. Ternary phase diagrams were constructed for syntheses at 90 °C for 1 week. The results reveal a cation-dependent continuous relation between batch stoichiometry and framework aluminum content, valid across the phase boundaries of all different zeolites formed in the system. The framework aluminum content directly correlates to the type of alkali cation and gradually changes with batch alkalinity and dilution. This suggests that the observed zeolites form through a solution-mediated mechanism involving the concerted assembly of soluble cation-oligomer ion pairs. Phase selection is a consequence of the stability for a particular framework at the given aluminum content and alkali type.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Ion-Pairs in Aluminosilicate-Alkali Synthesis Liquids Determine the Aluminum Content and Topology of Crystallizing Zeolites

et al. 2022

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“…Such an arrangement is reminiscent of the dense polyhedral networks in concentrated sodium hydroxide liquids. 55 , 56 …”

Section: Discussionmentioning

confidence: 99%

Nucleation of Porous Crystals from Ion-Paired Prenucleation Clusters

et al. 2022

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Current nucleation models propose manifold options for the formation of crystalline materials. Exploring and distinguishing between different crystallization pathways on the molecular level however remain a challenge, especially for complex porous materials. These usually consist of large unit cells with an ordered framework and pore components and often nucleate in complex, multiphasic synthesis media, restricting in-depth characterization. This work shows how aluminosilicate speciation during crystallization can be documented in detail in monophasic hydrated silicate ionic liquids (HSILs). The observations reveal that zeolites can form via supramolecular organization of ion-paired prenucleation clusters, consisting of aluminosilicate anions, ion-paired to alkali cations, and imply that zeolite crystallization from HSILs can be described within the spectrum of modern nucleation theory.

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“…The symmetry and full structural models, including Al as well as anion ordering, were determined using NMR crystallography. Combining X-ray diffraction with Rietveld refinement and advanced solid-state NMR in a NMR crystallography approach, [22] diffraction enables to selectively derive the structure and periodicity of the crystalline parts of a sample. NMR reveals local structural information on all phases present and exploits advanced experiments and filtering schemes, to highlight specific parts in the sample or selectively investigate well defined interactions between atoms.…”

Section: Introductionmentioning

confidence: 99%

NMR Crystallography Reveals Carbonate Induced Al‐Ordering in ZnAl Layered Double Hydroxide

Radhakrishnan

Lauwers

Chandran

et al. 2021

Chemistry A European J

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Super-ions of sodium cations with hydrated hydroxide anions: inorganic structure-directing agents in zeolite synthesis

Abstract: In inorganic zeolite formation, a direct correspondence between liquid state species in the synthesis and the supramolecular decoration of the pores in the as-made final zeolite has never been reported....

Cited by 19 publications

References 36 publications

Ion-Pairs in Aluminosilicate-Alkali Synthesis Liquids Determine the Aluminum Content and Topology of Crystallizing Zeolites

Ion-Pairs in Aluminosilicate-Alkali Synthesis Liquids Determine the Aluminum Content and Topology of Crystallizing Zeolites

Nucleation of Porous Crystals from Ion-Paired Prenucleation Clusters

NMR Crystallography Reveals Carbonate Induced Al‐Ordering in ZnAl Layered Double Hydroxide

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