Thermal studies of low silica zeolites and their magnesium exchanged forms

Chandrasekhar, S.; Pramada, P. N.

doi:10.1016/s0272-8842(01)00075-x

Cited by 31 publications

(15 citation statements)

References 11 publications

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“…This interpretation is in agreement with Weidenthaler and Schmidt, 21 Trigueiro and coworkers, 22 and Chandrasekhar and Pramada. 23,24 These authors recorded a similar exothermic effect in the DTA curves of many different cation forms of zeolites A, X and Y and ascribed it to the thermal breakdown of their microporous structure.…”

Section: Discussionmentioning

confidence: 80%

A comparative study of the thermal transformations of Ba-exchanged zeolites A, X and LSX

Esposito

Ferone

Pansini

et al. 2004

Journal of the European Ceramic Society

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Section: Discussionmentioning

confidence: 80%

A comparative study of the thermal transformations of Ba-exchanged zeolites A, X and LSX

Esposito

Ferone

Pansini

et al. 2004

Journal of the European Ceramic Society

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“…Tetrahedral of silicon-oxygen (SiO 4 ) and aluminum-oxygen (AlO 4 ) units repeat themselves in the three-dimensional network [28]. In their structure connected spaces, water molecules [29] and exchangeable alkaline or alkaline-earth charges such as Na + , K + , Ca 2+ , and Mg 2+ situated in two-dimensional channels [30]. Present cations that bonded to aluminum by electrostatic force, are easily exchangeable with other metal cations to maintain the natural neutralization [31].…”

Section: Introduction mentioning

confidence: 99%

Zeolite usage as source of silica to produce cordierite in MgO–Al2O3–SiO2 system

Parlak

Demirkıran

2018

J Adv Ceram

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In this study, natural zeolite was used as source of silica to produce cordierite. MgO and Al 2 O 3 were added to zeolite to obtain the cordierite stoichiometry. Mixture of these raw materials was mechanically activated for different durations. The mechanically activated powder mixture was characterized using XRD, DSC, SEM, specific surface area, and particle size analyzer. The pycnometer method was used to measure the densities of mechanically activated powder mixtures. Mechanically activated for 60 min powder mixture was sintered at 1150-1350 ℃ for 1 h. The sintering behavior of the samples was determined by measuring the linear shrinkage, density, and apparent porosity. The phases in the sintered samples were identified by XRD. Cordierite and spinel phases were detected for sintered at a temperature higher than 1150 ℃ but corundum accompanied to cordierite and spinel at 1150 ℃. The microstructure of the samples was examined using both SEM and AFM. The sintering behavior and microstructural properties of the samples changed with an increase in the sintering temperature. As the apparent porosity increased with increasing sintering temperature, linear shrinkage and density values decreased. Density values were determined as 2.31-2.69 g/cm 3 depending on the temperature. The grains coarsened at higher temperature and the average grain size depending on the temperature was 1.34-1.96 μm. From the results optimum sintering temperature was determined as 1250 ℃. Dense material was produced at a temperature as low as 1250 ℃ using zeolite as raw material.

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“…e incorporation of alkali metal cations increases the basicity of oxygen atoms, which are present in the framework of the zeolite [14]. e most common methods used for the preparation of such zeolite systems are ion exchange [15] and impregnation [13].…”

Section: Introductionmentioning

confidence: 99%

Dealuminated Beta Zeolite Modified by Alkaline Earth Metals

Chałupka

Sadek

Valentin

et al. 2018

Journal of Chemistry

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Alkaline Earth metals (Mg, Sr, and Ca) were incorporated into the dealuminated mesoporous beta zeolite (DeAlBeta) by the two-step postsynthesis method. Physicochemical properties of both unmodified and alkaline Earth metal-modified DeAlBeta zeolite were characterized by XRD, DR UV-vis, FTIR, TPD of NH3 and CO2, NMR, and XPS. The dealumination of beta zeolite led to decrease of its acidity and basicity. The incorporation of alkaline Earth metals into the framework of dealuminated beta zeolite did not affect its structure. The modification of DeAlBeta with a small amount of alkaline Earth metals increases the number of acidic centers, which may be related to the formation of framework Mg (Ca or Sr) (II) Lewis acidic sites.

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Thermal studies of low silica zeolites and their magnesium exchanged forms

Cited by 31 publications

References 11 publications

A comparative study of the thermal transformations of Ba-exchanged zeolites A, X and LSX

A comparative study of the thermal transformations of Ba-exchanged zeolites A, X and LSX

Zeolite usage as source of silica to produce cordierite in MgO–Al2O3–SiO2 system

Dealuminated Beta Zeolite Modified by Alkaline Earth Metals

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