In situ atomic force microscopy of zeolite A dissolution

Meza, L. Itzel; Anderson, Michael W.; Slater, Ben; Agger, Jonathan R.

doi:10.1039/b804857f

Cited by 34 publications

(6 citation statements)

References 34 publications

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“…This mechanism is common in classical crystallization, but has never been observed in situ for zeolites. Other groups have inferred this mode of growth using ex situ microscopy images 37 , 38 of LTA surfaces removed from saturated solutions and from in situ dissolution studies 39 in undersaturated media; however, such approaches are incapable of fully resolving the mechanisms of layer nucleation and spreading. On the contrary, we report time-resolved images in Fig.…”

Section: Resultsmentioning

confidence: 99%

Transient modes of zeolite surface growth from 3D gel-like islands to 2D single layers

2018

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Zeolite crystallization occurs by multifaceted processes involving molecule attachment and nonclassical pathways governed by the addition of amorphous precursors. Here, we use scanning probe microscopy to monitor zeolite LTA crystallization in situ with a spatiotemporal resolution that captures dynamic processes in real time. We report a distinctive pathway involving the formation of gel-like islands from supersaturated solutions comprised of (alumino)silicate molecules. Three-dimensional assembly and evolution of these islands constitutes a unique mode of growth that differs from classical theories. Time-resolved imaging also reveals that growth can occur by (nearly) oriented attachment. At later stages of crystallization, a progressive transition to lower supersaturation shifts growth to a layered mechanism involving two-dimensional nucleation and spreading of layers. Here, we show that LTA crystallization occurs by multiple pathways, thereby reconciling putative hypotheses of growth mechanisms while also highlighting new modes of nonclassical crystallization that may prove relevant to other zeolites and related materials.

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Section: Resultsmentioning

confidence: 99%

Transient modes of zeolite surface growth from 3D gel-like islands to 2D single layers

2018

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“…Though being recognized as one of the rate-limiting mechanisms of overall uptake and release, surface resistance has so far remained beyond direct experimental assessment and observation. This situation is changing with the development of microscopic techniques capable of atomistic resolution [22,36]. The detection and exploration of microstructural details, which might provide support for our model thus appears to be a promising project for future studies.…”

mentioning

confidence: 94%

“…The model assumes total blockage of the vast majority of the pore entrances, with only a few pores directly accessible from the outside. Several examples suggesting almost complete blockage of pores over an entire crystal plane can be found in the literature [21,22].…”

mentioning

confidence: 99%

Correlating Surface Permeability with Intracrystalline Diffusivity in Nanoporous Solids

Heinke

Kärger

2011

Phys. Rev. Lett.

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The rates of uptake and release of guest molecules in nanoporous solids are often strongly influenced or even controlled by transport resistances at the external surface ("surface barriers") rather than by intraparticle diffusion, which was assumed to be rate controlling in many of the earlier kinetic studies. By correlating the surface resistance with the intracrystalline diffusivity, we develop here a microkinetic model which closely reproduces the experimentally observed results for short-chain alkanes in Zn(tbip), a member of the novel metal-organic framework family of nanoporous materials. It seems likely that this mechanism, which is shown to provide a rational explanation of the commonly observed discrepancies between "macro" and "micro" measurements of intracrystalline diffusion, may be fairly general.

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“…When assuming the attachment of reactive plasma species on zeolite A, it seems that the preferred binding sites are on {111} surfaces. To the best of our knowledge, there is no direct report of the density of hydroxyl groups on {111} and {100} surfaces, while disputes remain regarding the surface terminations. − Therefore, we estimated the hydroxyl density for (100) and (111) surfaces following the cleavage strategy of a previous publication where the most stable positions for both surfaces were calculated . Surprisingly, The calculated density for the (100) surface is 5.63 OH groups nm –2 , much higher than that of the (111) surface (i.e., 2.44 OH groups nm –2 , Figure S5).…”

Section: Resultsmentioning

confidence: 87%

Molecular Modification of Zeolites with Cold Atmospheric-Pressure Plasma Jet: A Green and Facile Strategy

Batur

Duan

Jiang³

et al. 2023

Chem. Mater.

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Widespread applications of zeolites demand the optimization of crystal size and morphology. Crystal growth modifiers (CGMs) have been proved effective for zeolite rational design, but the additional chemicals raise environmental and safety concerns. Herein, the industry-ready technique of cold atmospheric-pressure plasma jet (CAPPJ) was employed to induce reactive plasma species as green and eco-friendly CGMs. The synthesis mixtures of three aluminosilicate zeolites with assorted Si/Al ratios (SAR), channel dimensionalities, and pore apertures (i.e., MFI, LTA, and LTL framework types) were first subjected to Ar-CAPPJ treatment for up to 30 min during the aging period. Apparent size and shape modifications were successfully achieved for the resulting crystals with the emergence of rounded surfaces implying surface roughening at the molecular level. For the silicoaluminophosphate SAPO-34 (CHA type), the introduction of plasma CGMs was found to propel a phase transformation, promoting the crystallization of SAPO-18 (AEI type) impurity with reduced framework density. Experimental observations seem to suggest that the classical model of CGMs attaching to selected crystal surfaces is less likely to happen. Whereas, the investigation of zeolite L dispersions revealed enhanced concentrations and altered physicochemical properties of soluble species and amorphous precursors, alluding to the potential functional mechanism (s) of plasma CGMs. As a plausible technique to generate green and versatile CGMs, the impacts of CAPPJ on zeolite crystallization are systematically investigated for the first time, promoting the understanding of classical and nonclassical crystallization phenomena during zeolite synthesis.

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In situ atomic force microscopy of zeolite A dissolution

Cited by 34 publications

References 34 publications

Transient modes of zeolite surface growth from 3D gel-like islands to 2D single layers

Transient modes of zeolite surface growth from 3D gel-like islands to 2D single layers

Correlating Surface Permeability with Intracrystalline Diffusivity in Nanoporous Solids

Molecular Modification of Zeolites with Cold Atmospheric-Pressure Plasma Jet: A Green and Facile Strategy

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