In situ 27Al NMR kinetic investigation of zeolite A crystallization

Miladinović, Zoran; Zakrzewska, Joanna; Kovačević, Branimir T.; Miladinović, Jelena

doi:10.1016/j.micromeso.2014.04.022

Cited by 20 publications

(13 citation statements)

References 54 publications

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“…However, it is difficult to apply if the length of the induction period t 0 , is not clear. 9,22 In the curve-fitting method, the right side of Equation (1) is expanded, By plotting experimental values of [-ln(1-α)] 1/n vs. t for various n values, the values of n and k that give a plot with the most linearity are adopted. This method has been widely used for the analysis of kinetic parameters, 23,24 because n and k can be directly obtained from the heating time t, and crystallinity α, without consideration of t 0. .…”

Section: Analysis Of Zeolite Beta Crystallization By Kinetic Analysismentioning

confidence: 99%

Kinetic analysis of crystallization of zeolite beta synthesized by direct heating

et al. 2020

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To quantitatively investigate the initial crystallization of zeolite beta synthesized by direct heating, the extent of the reaction was precisely evaluated by X-ray diffraction measurements and Rietveld structural refinement, and a kinetic analysis of crystallization was performed using the Avrami-Erofe'ev equation. The activation energy for crystallization was lower than that for hydrothermal synthesis. Reaction and synthesis time curves revealed that the initial zeolite beta crystallization consisted of three stages. The first was an induction period with nucleation by the generation of building units and the formation of an initial coordinated structure. The second stage was crystal growth by a diffusion-controlled reaction, and the third stage involved slowing down of crystallization by the limitation of dehydrocondensation. These stages could be analyzed by calculation of the rate constant and Avrami exponent for each stage.

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Section: Analysis Of Zeolite Beta Crystallization By Kinetic Analysismentioning

confidence: 99%

Kinetic analysis of crystallization of zeolite beta synthesized by direct heating

et al. 2020

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“…After deconvolution by the Gaussian / Lorentzian model of Dominique Massiot's software (DMFIT), this resonance, decomposed into two resonances at isotropic chemical shift values at 61.5 and 64.4 ppm, is assigned to the aluminum of the tetrahedral units. Several authors have shown that resonances detected in the range of chemical shifts 59-61 ppm are assigned to the tetra-coordinated 27 Al atoms of zeolites NaA and NaP (Glid et al, 2017, Kulshreshtha et al, 2013, Xiao et al, 2017, Albert et al, 1998, Nery et al, 2003, Meftah et al, 2017, Miladinović et al, 2014, but with a slightly lower chemical shift for NaP ( about 1 ppm) to that of NaA (Wartel et al, 2018, Zubowa et al, 2008, Frost and Vassallo, 1996. The chemical shift at 61.5 ppm can be attributed to the tetra-coordinated 27 Al atoms of the zeolites NaP since the X-ray showed the presence of zeolite phase P. On this spectrum, we notice the absence of peaks between 0 and 10 ppm probably due to an absence of extra-lattice aluminum or a problem of limit of detection.…”

Section: X-ray Diffractionmentioning

confidence: 99%

Zeolitization of kaolin from M'Batra village (Cote d’Ivoire) by NaOH and Na2O.SiO2 treatment

2019

Aust. J. Basic & Appl. Sci

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Kaolin has been used as an alternative cheap raw material for the synthesis of zeolite NaY. The objective of this study is to synthesize a zeolite NaY from a natural clay (kaolin) from M'Batra. Two steps are involved in the reaction: (1) dehydroxylation of kaolin at 550°C to form an amorphous material called metakaolin; (2) hydrothermal treatment of metakaolin with aqueous alkali to form the zeolite. SEM, BJH and BET techniques were used respectively to study the morphology, pore size distribution and adsorption-desorption isotherms of N2 at 77 K. Structural and compositional studies were conducted using X-ray fluorescence (XRF), solid-state nuclear magnetic resonance of 27 Al and 29 Si. XRF analysis showed an increase in the Si/Al ratio of 1.91 to 2.95 compared to natural clay. The SEM of the zeolite NaY gave a homogeneous and porous material. The specific surface area of the zeolite NaY increased by 5.03 times compared to the natural clay. The XRD of the zeolite NaY showed a well crystallized material. The MAS NMR spectrum of 27 Al revealed a single Al environment. In conclusion, the results of the different characterizations show us that the material obtained by modification of the natural clay (kaolin) of M'Batra has a zeolithic structure.

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“…The simultaneous changes in intensity and shape of both NMR lines are indicative of depletion of [Al(OH) 4 ] − ions from the liquid phase and the building up of a Al(OSi) 4 tetrahedral network at the surface of zeolite crystal particles [30]. Both alkalinity and dilution effects have been investigated on various gels with wide molar composition range.…”

Section: Examples Of In Situ Nmr Studies On Crystallization Of Micmentioning

confidence: 99%

“…The same system, i.e., zeolite A, has also been subjected to in situ NMR study using conventional liquid state NMR. Miladinovic et al used 10 mm Quartz tubes to study suspension (dilute gel) precursors for zeolite A at relatively mild temperatures not exceeding 80 °C [ 30 , 57 ]. With this method, they identified signatures for species in both liquid and solid phases that they can monitor simultaneously during the synthesis course ( Figure 5 ).…”

Section: Examples Of In Situ Nmr Studies On Crystallization Of Micmentioning

confidence: 99%

“…To verify such postulated mechanisms, kinetic investigation of the crystallization process represents one of the most effective experimental approaches [ 29 , 30 , 31 ]. These methods became more asserted through in situ approach, enabling sufficient number of experimental data required for precise kinetics and thermodynamics analyses [ 32 ].…”

Section: Introductionmentioning

confidence: 99%

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Nuclear Magnetic Resonance Spectroscopy for In Situ Monitoring of Porous Materials Formation under Hydrothermal Conditions

Haouas

2018

Materials

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The employment of nuclear magnetic resonance (NMR) spectroscopy for studying crystalline porous materials formation is reviewed in the context of the development of in situ methodologies for the observation of the real synthesis medium, with the aim of unraveling the nucleation and growth processes mechanism. Both liquid and solid state NMR techniques are considered to probe the local environment at molecular level of the precursor species either soluble in the liquid phase or present in the reactive gel. Because the mass transport between the liquid and solid components of the heterogeneous system plays a key role in the synthesis course, the two methods provide unique insights and are complementary. Recent technological advances for hydrothermal conditions NMR are detailed and their applications to zeolite and related materials crystallization are illustrated. Achievements in the field are exemplified with some representative studies of relevance to zeolites, aluminophosphate zeotypes, and metal-organic frameworks.

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In situ 27Al NMR kinetic investigation of zeolite A crystallization

Cited by 20 publications

References 54 publications

Kinetic analysis of crystallization of zeolite beta synthesized by direct heating

Kinetic analysis of crystallization of zeolite beta synthesized by direct heating

Zeolitization of kaolin from M'Batra village (Cote d’Ivoire) by NaOH and Na2O.SiO2 treatment

Nuclear Magnetic Resonance Spectroscopy for In Situ Monitoring of Porous Materials Formation under Hydrothermal Conditions

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