Comparative study of the active sites in zeolites by different probe molecules

Dondur, V.; Rakić, Mina; Damjanovic, S Ljiljana; Auroux, A.

doi:10.2298/jsc0503457d

Cited by 21 publications

(12 citation statements)

References 40 publications

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“…The maximum temperature desorption peak was used to characterize the strength of acidity according to the classification. The NaY5.1, NH 4 Y5.1, NH 4 Y5.2, HY5.2, and HY30 samples showed NH 3 TPD profiles consistent with those reported in the literature [32]. The NH 4 Y5.1 zeolite has the highest total acidity in the two defined regions.…”

Section: Temperature Programmed Desorption (Tpd)supporting

confidence: 86%

Nanoporosity of MCM-41 Materials and Y-Zeolites Created by Deposition of Tournefortia hirsutissima L. Plant Extract

Hernández

Portillo

et al. 2017

Journal of Nanomaterials

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Hybrid materials based on MCM-41 silica and Y-zeolites with a variable Si/Al ratio and an appropriate countercationic composition were prepared by impregnating inorganic substrates with an organic extract. The organic phase was previously characterized by GC-MS and IRTF, while XRD, SEM, TEM, N 2 -physisorption, and TPD of NH 3 were used to analyze the selected inorganic supports. The effect of size-and shape-selectivity was manifested in MCM-41 and Y-zeolites. Texture results confirm that the extract containing relatively large branched organic molecules is deposited in the internal voids of MCM-41 material and on the outer area of Yzeolites. In the case of Y-zeolites, the results demonstrate the effect of the SiO 2 /Al 2 O 3 molar ratio and countercations on the textural properties of the samples.

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Section: Temperature Programmed Desorption (Tpd)supporting

confidence: 86%

Nanoporosity of MCM-41 Materials and Y-Zeolites Created by Deposition of Tournefortia hirsutissima L. Plant Extract

Hernández

Portillo

et al. 2017

Journal of Nanomaterials

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“…The figure demonstrates that the predictions are significantly different between two force fields. A comparison with the literature data demonstrates that the prediction with the new force field agrees well with the experimental measurements [18] . The Catlow-Faux force field failed to describe the interaction between ammonia molecules and zeolite correctly; the ammonia leaves the zeolite surface too easily.…”

Section: Ammonia Adsorption In Zeolitesupporting

confidence: 77%

Prediction of adsorption of small molecules in porous materials based on ab initio force field method

Liu

Jia

Sun

2008

Sci. China Ser. B-Chem.

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Computational prediction of adsorption of small molecules in porous materials has great impact on the basic and applied research in chemical engineering and material sciences. In this work, we report an approach based on grand canonical ensemble Monte Carlo (GCMC) simulations and ab initio force fields. We calculated the adsorption curves of ammonia in ZSM-5 zeolite and hydrogen in MOF-5 (a metal-organic-framework material). The predictions agree well with experimental data. Because the predictions are based on the first principle force fields, this approach can be used for the adsorption prediction of new molecules or materials without experimental data as guidance.Porous materials, adsorption, ab initio force field, Grand Canonical ensemble Monte Carlo Adsorption of gaseous or liquid small molecules in porous materials has great potentials in wide-spread applications. For example, zeolites, a group of crystalline silicon/alumina oxides with nano-scale porous structures, have been widely used in the fine chemical and oil industries [1][2][3] for their capabilities of ion-exchange, catalysis, and adsorption; Metal organic frameworks (MOFs), a new type of materials with extremely large surfaces and controllable pore sizes, have been explored for the hydrogen storage purpose with great interest [4][5][6][7] . The adsorption of small molecules in porous materials is extremely important for the application of these materials. In zeolites, the pore structures, capabilities of adsorption of reactants and acidities play significant roles in determining their catalytic properties. For MOFs, the ability of adsorbing hydrogen molecules on their surfaces directly reflects their capacity of hydrogen storage. Therefore, to study the adsorption of small molecules in porous materials is of great interest.Significant progress has been made in studying adsorption of small molecules in porous materials using experimental methods. Researchers have gained substantial knowledge of the chemical and physical properties of porous materials using techniques such as the BET isotherms measurement and Temperature-Programmed Desorption (TPD). However, due to inherent limitations of experimental measurements, it is difficult to reveal the mechanism of small molecules on the surfaces at the microscopic level, where the theoretical or computational approaches can be very valuable. In recent years, with the fast development of quantum chemistry and molecular modeling methods, computational chemistry methods have been widely used in studying the adsorption of small molecules in porous materials. The advantage of the computational approach is that it can provide more precise description of the behavior of guest molecules in the porous materials, explain the experimental observed phenomena and perhaps predict the adsorption under different conditions. Among various computational approaches, the grand canonical ensemble Monte Carlo (GCMC) method is capable for predicting the phase equilibrium of gas molecules and the adsorbent directly.Underlying th...

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“…Indeed, a large variety of probe molecules such as NH3, pyridine, amines, H2O, N2O, etc. has been studied [106][107][108]. The results are plotted as the adsorption enthalpy as a function of the coverage.…”

Section: Zeolites' Acidity Assessment By Probe Moleculesmentioning

confidence: 99%

Analysis and control of acid sites in zeolites

Palčić

Valtchev

2020

Applied Catalysis A: General

107

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The exceptional catalytic performance of zeolites is due to the presence of active sites in a shape-selective environment, i.e., in micropores with molecular dimensions. The present review provides a comprehensive analysis of active sites in zeolite frameworks. It is focused on the active sites generated by the Al incorporation in the framework. The inclusion of other heteroatoms in the zeolite framework is also addressed. After the introduction of zeolite-type materials and a discussion of the structure-properties relationship in zeolites the central part of the review is devoted to i) the analytical methods and their complementarity for the evaluation of the number, strength, and position of active sites and ii) the in situ and post-synthesis methods of acid sites assessment and control. The data presented herein provide guidelines for making zeolite materials by design in terms of acidity.

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Comparative study of the active sites in zeolites by different probe molecules

Cited by 21 publications

References 40 publications

Nanoporosity of MCM-41 Materials and Y-Zeolites Created by Deposition of Tournefortia hirsutissima L. Plant Extract

Nanoporosity of MCM-41 Materials and Y-Zeolites Created by Deposition of Tournefortia hirsutissima L. Plant Extract

Prediction of adsorption of small molecules in porous materials based on ab initio force field method

Analysis and control of acid sites in zeolites

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