One-dimensional intergrowths in two-dimensional zeolite nanosheets and their effect on ultra-selective transport

Kumar, Prashant; Kim, Dae Woo; Rangnekar, Neel; Xu, Hao; Fetisov, Evgenii O.; Ghosh, Supriya; Zhang, Han; Xiao, Qiang; Shete, Meera; Siepmann, J. Ilja; Dumitrică, Traian; McCool, Benjamin A.; Tsapatsis, Michael; Mkhoyan, K. Andre

doi:10.1038/s41563-019-0581-3

Cited by 108 publications

(109 citation statements)

References 52 publications

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“…Simultaneously, the relative significance of surface barriers for the overall process is seen to increase with decreasing particle sizes since the time constant (and, correspondingly, the associated resistance) scales only linearly rather than with the square of the particle size. Permeances of, e.g., zeolite membranes must therefore be expected to be increasingly controlled by surface effects rather than by their intracrystalline diffusivities with decreasing thickness (Caro and Kärger 2020;Kumar et al 2020). Teixeira et al (2013) nicely demonstrates this behavior by evidencing, in ZLC diffusion measurements with cyclohexane in silicalite, transition from internal diffusion control with large crystals to surface resistance control for small crystals.…”

Section: Surface Barriersmentioning

confidence: 88%

Diffusion in nanopores: inspecting the grounds

2020

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This paper provides a general overview of the phenomenon of guest diffusion in nanoporous materials. It introduces the different types of diffusion measurement that can be performed under both equilibrium and non-equilibrium conditions in either single- or multicomponent systems. In the technological application of nanoporous materials for mass separation and catalytic conversion diffusion often has a significant impact on the overall rate of the process and is quite commonly rate controlling. Diffusion enhancement is therefore often a major goal in the manufacture of catalysts and adsorbents.

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Section: Surface Barriersmentioning

confidence: 88%

Diffusion in nanopores: inspecting the grounds

2020

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“…There are some recent prominent papers to synthesize porous nanosheets and to arrange them as membrane stack as shown in Fig. 3b, zeolite nanosheets (Kumar et al 2020), and MOF nanosheets (Rodenas et al 2015 andPeng et al 2014). The perspectives of such membrane structure have been recently highlighted recently (Caro and Kärger 2020).…”

Section: Diffusion Studies On Mixed Matrix Membranes (Mmms)mentioning

confidence: 99%

Diffusion coefficients in nanoporous solids derived from membrane permeation measurements

Caro

2020

Adsorption

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Based on the molecular understanding of the interplay of diffusion and adsorption, new membrane materials can be developed and the operational conditions of gas separation membranes can be optimized. Therefore, numerous diffusion and adsorption studies are conducted to optimize membrane materials. However, in an opposite way, transport or Fickian diffusion coefficients DT can be derived from membrane permeation studies with surprising accuracy. From measuring the gas transport through nanoporous supported thin-layer membranes or through mixed matrix membranes with nanoporous fillers in a polymer matrix, the transport diffusion coefficients DT of gases in novel nanoporous materials such as zeolites, MOFs, COFs… can be estimated.

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“…With the implementation of spherical aberration (C s ) correctors coupled with more and better electron detectors, lateral resolution is significantly improved for such beam sensitive materials.V ery recently,P rashant et al [23] have succeeded in the synthesis of very well controlled MFI nanosheets with al ateral area of 200 nm 200 nm and uniform thickness of only 3.2 nm along the b-axis.T he authors found that one to few unit cells intergrowths of MEL domains were inserted along the a-axis in the MFI framework and extended along the c-axis.B ased on ultrahigh resolution C s -corrected STEM data using an annular dark field detector (ADF), they identified the planar modulation distribution of these MEL domains,a nd showed that af raction of nanosheets have as ignificant amount of MEL content ( % 25 %b yv olume) while the majority of nanosheets are purely MFI.T his work combined traditional SAED patterns collection and analysis with state-of-art EM observations,i mage treatment and data analysis (Figure 11). In here,anintergrowth of a MEL band was observed between the two MFI domains,which are in mirror relation to each other through the MEL band perpendicular to the a-axis (Figure 11 a).…”

Section: New Advancesmentioning

confidence: 99%

Electron Microscopy Studies of Local Structural Modulations in Zeolite Crystals

Zhang

Mayoral

et al. 2020

Angewandte Chemie

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Zeolites are widely used in catalysis, gas separation, ion exchange, etc. due to their superior physicochemical properties, which are closely related to specific features of their framework structures. Although more than two hundred different framework types have been recognized, it is of great interest to explore from a crystallographic perspective, the atomic positions, surface terminations, pore connectivity and structural defects that deviate from the ideal framework structures, namely local structural modulation. In this article, we review different types of local modulations in zeolite frameworks using various techniques, especially electron microscopy (EM). The most recent advances in resolving structural information at the atomic level with aberration corrected EM are also presented, commencing a new era of gaining atomic structural information, not only for all tetrahedral atoms including point vacancies in framework but also for extra‐framework cations and surface terminations.

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One-dimensional intergrowths in two-dimensional zeolite nanosheets and their effect on ultra-selective transport

Cited by 108 publications

References 52 publications

Diffusion in nanopores: inspecting the grounds

Diffusion in nanopores: inspecting the grounds

Diffusion coefficients in nanoporous solids derived from membrane permeation measurements

Electron Microscopy Studies of Local Structural Modulations in Zeolite Crystals

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