Water‐Induced Structural Dynamic Process in Molecular Sieves under Mild Hydrothermal Conditions: Ship‐in‐a‐Bottle Strategy for Acidity Identification and Catalyst Modification

Sun, Tantan; Xu, Shutao; Xiao, Dong; Liu, Zhiqiang; Li, Guangchao; Zheng, Anmin; Liu, Wenjuan; Xu, Zhaochao; Cao, Yi; Guo, Qiang; Wang, Nan; Wei, Yingxu; Liu, Zhongmin

doi:10.1002/ange.202009648

Cited by 10 publications

(16 citation statements)

References 59 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In order to investigate the origins and driving-force behind the unusual acetone type-II state, other SAPO zeolites (H-SAPO-18 and H-SAPO-35) were studied using similar methods. Similar results were also observed in the 13 C chemical shifts of 13 . S10b and S10d).…”

supporting

confidence: 87%

“…24 Therefore, we assigned the minor 225 ppm peak to 13 C-acetone adsorbed at LAS. The analysis of 2D 13 C-1 H hetero-nuclear correlation NMR spectra further supports our assignment as shown in Fig. 1d.…”

supporting

confidence: 86%

“…Using SSNMR and DFT calculations, Morris et al 11,12 con rmed that framework Al-O bonds in zeolites can be reversibly broken through the adsorption and desorption of water at room temperature. Very recently, Liu et al 13 observed the same phenomenon using SSNMR. All of these observations indicate that the BAS structure is not completely stable and possesses some unquenched reactivity.…”

mentioning

confidence: 55%

“…According to the previous literature, 21 the major peak at 217 ppm is attributed to 13 C-acetone adsorbed on BAS. However, the other 13 C resonance at 225 ppm persistently appears in repeated measurements but remained ambiguous. One may consider the signal at 225 ppm to be attributed to the acetone adsorbed on the stronger BAS, 22,23 and/or acetone adsorbed at surface defects.…”

mentioning

confidence: 99%

“…Figs. 2a-c show the 13 C CP MAS SSNMR spectrum of 13 Cmethanol adsorbed on H-SAPO-34, H-SAPO-18, and H-SAPO-35 zeolites, respectively at 298K. In contrast to acetone adsorption, in which two signals that corresponded to the two adsorption modes were deconvoluted, for methanol the Gaussian deconvolution clearly required three peaks at 50.4 ppm, 52.8 ppm and 56.4 ppm.…”

mentioning

confidence: 99%

See 4 more Smart Citations

Adsorbate-induced Active Site in Zeolite

Li¹,

Foo²,

Yi³

et al. 2020

Preprint

Self Cite

View full text Add to dashboard Cite

There has been a long debate on how and where active sites are created for molecular adsorption and catalysis in zeolites which underpin many important industrial applications. For example, Lewis acidic site (LAS) and basic site (LBS) are generally believed to be the extra-framework Al species and residue anion (OH−) species formed at fixed crystallographic positions on the zeolite structures after their synthesis. Here, direct experimental observation of adsorbate-induced active sites in silicoaluminophosphate (SAPO) zeolites is for the first time made, which contradicts the traditional view of the fixed active sites in zeolites. Evidence shows that induced Frustrated Lewis pair (three-coordinated framework Al as LAS and SiO(H) as LBS) can be transiently favored for heterolytic molecular binding/reactions of competitive polar adsorbates due to their ineffective orbitals overlap in the rigid framework. High resolution magic-angle spinning solid-state nuclear magnetic resonance (MAS-SSNMR), synchrotron X-ray diffraction (SXRD), neutron powder diffraction (NPD), in-situ Diffuse Reflectance Infrared Fourier Transform spectroscopy (in-situ DRIFT) and ab initio molecular dynamic (AIMD) demonstrate the presence of only one type of Bronsted acid site (BAS) in the H-SAPO-34, however, when exposed to polar adsorbates such as methanol, the methoxy moiety is shown to be directly coordinated to the framework Al (induced LAS) and the proton to the O(H)-Si (induced LBS) by the induced FLP. Our unprecedented finding opens up a new avenue to understanding of the dynamic establishment of active sites for adsorption or chemical reactions under molecular bombardments to zeolitic structures.

show abstract

supporting

confidence: 87%

supporting

confidence: 86%

mentioning

confidence: 55%

mentioning

confidence: 99%

mentioning

confidence: 99%

See 3 more Smart Citations

Adsorbate-induced Active Site in Zeolite

Li¹,

Foo²,

Yi³

et al. 2020

Preprint

Self Cite

View full text Add to dashboard Cite

show abstract

High‐Silica CHA Zeolite Membrane with Ultra‐High Selectivity and Irradiation Stability for Krypton/Xenon Separation

et al. 2021

View full text Add to dashboard Cite

Capture and storage of the long-lived 85 Kr is an efficient approach to mitigate the emission of volatile radionuclides from the spent nuclear fuel reprocessing facilities. However,itischallenging to separate krypton (Kr) from xenon (Xe) because of the chemical inertness and similar physical properties.H erein we prepared high-silica CHA zeolite membranes with ultra-high selectivity and irradiation stability for Kr/Xe separation. The suitable aperture sizea nd rigid framework endures the membrane as trong size-exclusion effect. The ultrahigh selectivity of 51-152 together with the Kr permeance of 0.7-1.3 10 À8 mol m À2 s À1 Pa À1 of high-silica CHA zeolite membranes far surpass the state-of-the-art polymeric membranes.T he membrane is among the most stable polycrystalline membranes for separation of humid Kr/ Xe mixtures.T ogether with the excellent irradiation stability, high-silica CHA zeolite membranes pave the way to separate radioactive Kr from Xe for anotable reduction of the volatile nuclear waste storage volume.

show abstract

Thermal Alteration in Adsorption Sites over SAPO‐34 Zeolite

Yoskamtorn

Chen

et al. 2022

Angewandte Chemie

Self Cite

View full text Add to dashboard Cite

Zeolites have found tremendous applications in the chemical industry. However, the dynamic nature of their active sites under the flow of adsorbate molecules for adsorption and catalysis is unclear, especially in operando conditions, which could be different from the as‐synthesized structures. In the present study, we report a structural transformation of the adsorptive active sites in SAPO‐34 zeolite by using acetone as a probe molecule under various temperatures. The combination of solid‐state nuclear magnetic resonance, in situ variable‐temperature synchrotron X‐ray diffraction, and in situ diffuse‐reflectance infrared Fourier‐transform spectroscopy allow a clear identification and quantification that the chemisorption of acetone can convert the classical Brønsted acid site adsorption mode to an induced Frustrated Lewis Pairs adsorption mode at increasing temperatures. Such facile conversion is also supported by the calculations of ab‐initio molecular‐dynamics simulations. This work sheds new light on the importance of the dynamic structural alteration of active sites in zeolites with adsorbates at elevated temperatures.

show abstract

Water‐Induced Structural Dynamic Process in Molecular Sieves under Mild Hydrothermal Conditions: Ship‐in‐a‐Bottle Strategy for Acidity Identification and Catalyst Modification

Cited by 10 publications

References 59 publications

Adsorbate-induced Active Site in Zeolite

Adsorbate-induced Active Site in Zeolite

High‐Silica CHA Zeolite Membrane with Ultra‐High Selectivity and Irradiation Stability for Krypton/Xenon Separation

Thermal Alteration in Adsorption Sites over SAPO‐34 Zeolite

Contact Info

Product

Resources

About