The non-isothermal kinetic analysis of the thermal decomposition of kaolinite by thermogravimetric analysis

Ptáček, Petr; Kubátová, Dana; Havlica, Jaromír; Brandštetr, Jiří; Šoukal, František; Opravil, Tomáš

doi:10.1016/j.powtec.2010.08.004

Cited by 94 publications

(39 citation statements)

References 26 publications

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“…The overall activation energy and frequency factor were 242 kJ mol -1 and 2.21 9 10 8 s -1 , respectively. Kinetic calculations with the results of TG experiments performed with heating rates in the range from 1 to 40°C min -1 gave the overall activation energy and frequency factor to 227 ± 1 kJ mol -1 and (9.4 ± 0.3) 9 10 9 s -1 [13], respectively, which were very similar to these obtained from EGA results [12].…”

Section: Introductionsupporting

confidence: 79%

Heating rate effect on the thermal behavior of some clays and their blends with oil shale ash additives

Kaljuvee

Štubňa

Húlan

et al. 2016

J Therm Anal Calorim

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The heating rate effect on the thermal behavior of clays from Arumetsa and Kunda deposits (Estonia) and an illitic clay from Füzérradvány (Hungary) was studied. Experiments were carried out under dynamic heating condition up to 1050°C at the heating rates of 1.25, 2.5, 5 and 10°C min -1 in a stream of gas mixture containing 79 % of Ar and 21 % of O 2 with Setaram Labsys 1600 analyzer. Two different ashes were used as additives: the electrostatic precipitator ash from the first field and the cyclone ash formed, respectively, at circulating fluidized bed combustion (temperatures 750-830°C) and pulverized firing (temperatures 1200-1400°C) of Estonian oil shale at Estonian Power Plant. For calculation of kinetic parameters, the TG data were processed by the differential isoconversional Friedman method. The results of thermal analysis and the variation of the value of activation energy E along the reaction progress a indicated the complex character of decomposition of clays and their blends with Estonian oil shale ashes, and the certain differences in thermal behavior of different clays depending on their origin.

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Section: Introductionsupporting

confidence: 79%

Heating rate effect on the thermal behavior of some clays and their blends with oil shale ash additives

Kaljuvee

Štubňa

Húlan

et al. 2016

J Therm Anal Calorim

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“…Table lists the values of R 2 obtained over interval 0.25 ≤ x ≤ 0.75. The results in bold are marking the most probable kinetic mechanism [13].…”

Section: Discussionmentioning

confidence: 99%

Mechanism and Kinetic Parameters of the Thermal Decomposition of Gibbsite Al(OH)₃ by Thermogravimetric Analysis

et al. 2017

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In this study, the mechanism and the kinetic parameters of the thermal decomposition of gibbsite Al(OH)3 were studied by differential thermogravimetry technique under non-isothermal conditions, between room temperature and 1200 K at heating rates of 5, 10, 15 and 20The obtained differential thermogravimetry curves show clearly three distinct peaks. The first peak is due to the partial dehydroxylation of gibbsite. Among the 32 types of differential equations of non-isothermal kinetics, we have found that the most suitable mechanism is (A 3/2 :2/3 ) also called Avrami-Erofeev equation of order 2/3. The values of the activation energy EA and of the pre-exponential factor K are 157 kJ mol −1 and 7.58 × 10 15 s −1 , respectively. The second peak corresponds to the decomposition of gibbsite to boehmite. Decomposition is controlled by the rate of second-order reaction (F2: g(x) = (1 − x) −1 − 1), under the applied conditions. The activation energy EA and pre-exponential factor K correspond to 243 kJ mol −1 and 3.73 × 10 22 s −1 , respectively. The third peak is due to transformation of boehmite to alumina. However the mechanism for such transformation is better described by the 3/2 rate order reaction (F 3/2 : g(x) = (1 − x) −1/2 − 1). In addition, the values of EA and K were determined to be around 296 kJ mol −1 and 1.82 × 10 19 s −1 , respectively. The results of differential thermogravimetry were supplemented by the differential thermal analysis. X-ray powder diffraction analysis was carried out for samples of gibbsite treated at different temperatures between 200 and 1200• C in 200• C steps.

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“…This value is close to 1.5, which suggests, that the crystallization process of meta-kaolinite should be controlled by diffusion growth [14]. The dimensionality of crystal growth m, calculated from the slope of the function ln(v n /T 2 p ) = f (1/T p ), according to Matusita (Eq.…”

Section: Resultsmentioning

confidence: 60%

“…From the ratio of times for two fixed degrees of transformation, the morphology of the crystal growth can be obtained [13,14]. A suitable representative index is the ratio of times for 75% and 25% transformation.…”

Section: Resultsmentioning

confidence: 99%

Thermal Decomposition Kinetics of Algerian Tamazarte Kaolin by Differential Thermal Analysis (DTA)

et al. 2017

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In the present study, the kinetics of meta-kaolinite (Al2O3·2SiO2) formation from Algerian Tamazarte kaolin was investigated by using differential thermal analysis. The differential thermal analysis and the thermogravimetric experiments were carried out on samples between room temperature and 1400• C, at heating rates from 10 to 40• C min −1 . X-ray diffraction was used to identify the phases present in the samples. The activation energies measured by differential thermal analysis from isothermal and non-isothermal treatments using Johnson-MehlAvrami methods with Ligero approximation and using Kissinger-Akahira-Sunose methods were around 145 and 159 kJ/mol, respectively. The Avrami parameter n which indicates the growth morphology parameters were found to be almost equal to 1.60, using non-isothermal treatments, and equal to 1.47 using isothermal treatments. The numerical factor which depends on the dimensionality of crystal growth was 1.60 obtained using Matusita et al. equation. The frequency factor calculated using the isothermal treatment is equal to 1.173 × 10 7 s −1 . Analysis of the results have shown that bulk nucleation was dominant during kaolinite transformation, followed by three-dimensional growth of meta-kaolinite with polyhedron-like morphology, controlled by diffusion from a constant number of nuclei.

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The non-isothermal kinetic analysis of the thermal decomposition of kaolinite by thermogravimetric analysis

Cited by 94 publications

References 26 publications

Heating rate effect on the thermal behavior of some clays and their blends with oil shale ash additives

Heating rate effect on the thermal behavior of some clays and their blends with oil shale ash additives

Mechanism and Kinetic Parameters of the Thermal Decomposition of Gibbsite Al(OH)₃ by Thermogravimetric Analysis

Thermal Decomposition Kinetics of Algerian Tamazarte Kaolin by Differential Thermal Analysis (DTA)

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The non-isothermal kinetic analysis of the thermal decomposition of kaolinite by thermogravimetric analysis

Cited by 94 publications

References 26 publications

Heating rate effect on the thermal behavior of some clays and their blends with oil shale ash additives

Heating rate effect on the thermal behavior of some clays and their blends with oil shale ash additives

Mechanism and Kinetic Parameters of the Thermal Decomposition of Gibbsite Al(OH)3 by Thermogravimetric Analysis

Thermal Decomposition Kinetics of Algerian Tamazarte Kaolin by Differential Thermal Analysis (DTA)

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Mechanism and Kinetic Parameters of the Thermal Decomposition of Gibbsite Al(OH)₃ by Thermogravimetric Analysis