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Journal ArticleDOI

The determination of activation energy from linear heating rate experiments: a comparison of the accuracy of isoconversion methods

04 Sep 2003-Thermochimica Acta (Elsevier)-Vol. 404, Iss: 1, pp 163-176
TL;DR: In this article, a classification of model-free isoconversion methods for the calculation of activation energies of thermally activated reactions is proposed, by deriving expressions for the main sources of error which includes the inaccuracy in reaction rate measurement, approximations for the temperature integral and inaccuracies in determination of temperature for equivalent fraction transformed.
About: This article is published in Thermochimica Acta.The article was published on 2003-09-04 and is currently open access. It has received 1393 citations till now.
Citations
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Journal ArticleDOI
TL;DR: In this article, the authors have developed recommendations for reliable evaluation of kinetic parameters (the activation energy, the preexponential factor, and the reaction model) from the data obtained by means of thermal analysis methods such as TGA, differential scanning calorimetry (DSC), and differential thermal analysis (DTA).

4,112 citations


Cites background from "The determination of activation ene..."

  • ...Many of these approximations give rise to linear equations of the general form [17]:...

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  • ...This is especially importantwhen choosing betweennumerous integral model-fitting methods whose accuracy in evaluating lnAi and Ei depends largely on the accuracy of the approximation of the temperature integral [17,49,50]....

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  • ...As shown by Starink [17], somewhat more accurate estimates of E ̨ are accomplished when setting B=1....

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  • ..., DSC and DTA), significant inaccuracy in the rate values can be introduced due to the difficulty of determining the baseline [17]....

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Journal ArticleDOI
TL;DR: A broad review of the state-of-the-art biomass pyrolysis research can be found in this article, where three major components (cellulose, hemicellulose and lignin) are discussed in detail.

1,613 citations

Journal ArticleDOI
TL;DR: A critical review of kinetic models and mathematical approximations currently employed in solid state thermal analysis is provided and analysis of thermal decomposition data obtained from two agricultural residues, nutshells and sugarcane bagasse reveals the inherent difficulty and risks involved in modeling heterogeneous reaction systems.

976 citations

Journal ArticleDOI
TL;DR: A variance in the activation energy with conversion was observed when the KAS and OFW models were employed, which reveals that the pyrolysis of cardoon progresses through more complex and multi-step kinetics.

435 citations


Cites methods from "The determination of activation ene..."

  • ...By introducing the approximation (Starink, 2003; Sbirrazzuoli et al., 1999 Starink, 2007; Doyle, 1965)....

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Journal ArticleDOI
TL;DR: The present recommendations provide guidance on kinetic analysis of multi-step processes as measured by thermal analysis methods such as thermogravimetry and differential scanning calorimetry.

395 citations

References
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Journal ArticleDOI
01 Jan 1964-Nature
TL;DR: In this article, a thermocouple is used to measure the sample temperature in a Stanton HT-D thermobalance, the bead of which is positioned in or near the sample, depending on crucible design.
Abstract: THE use of thermogravimetric data to evaluate kinetic parameters of solid-state reactions involving weight loss (or gain) has been investigated by a number of workers1–4. Freeman and Carroll2 have stated some of the advantages of this method over conventional isothermal studies. To these reasons may be added the advantage of using one single sample for investigation. However, the importance of procedural details, such as crucible geometry, heating rate, pre-history of sample, and particle size, on the parameters has yet to be fully investigated. It is also necessary to ensure accurate temperature measurement, both for precision and also to detect any departure from a linear heating rate due to endo- or exo-thermic reactions. (The effect of these may be largely eliminated by the use of small samples.) In our present work (using a Stanton HT–D thermobalance) the sample temperature is measured directly by means of a thermocouple the bead of which is positioned in or near the sample, depending on crucible design, the wires of which run down a twin-bore rise rod. The connexion between the end of the thermocouple wires on the balance arm and the terminal block is made by 0.001 in. platinum and platinum/rhodium wires5. It has been shown that these wires do not affect the performance of the balance but act merely as a subsidiary damping. From the terminal block compensated cable leads to the cold junction and a potentiometric arrangement for direct measurement of the thermocouple output.

5,770 citations

Journal ArticleDOI
TL;DR: In this article, the temperature at which the maximum deflection is observed varies with heating rate for certain types of reactions, and an expression can be derived relating this variation with the kinetics of the reaction.
Abstract: In differential thermal analysis, the temperature at which the maximum deflection is observed varies with heating rate for certain types of reactions. An expression can be derived relating this variation with the kinetics of the reaction. By making a number of differential thermal patterns at different heating rates, the kinetic constants can be obtained directly from the differential thermal data. Measurements of the variation of peak temperature with heating rate have been made for several minerals of the kaolin group, the values of the kinetic constants determined, and these values compared with corresponding values obtained for both the same samples and similar material by conventional isothermal techniques. Some factors affecting the results are discussed. The method of differential thermal analysis (DTA) has been universally accepted by mineralogical laboratories as a rapid and convenient means for recording the thermal effects that occur as a sample is heated. Changes in heat content of the active sample are indicated by deflections shown by a line representing the differential temperature. It is conventional to represent an endothermic effect by a negative deflection and an exothermic effect by a positive deflection. The deflections, whether positive or negative, are called peaks.

3,138 citations

Journal ArticleDOI
TL;DR: In this article, a technique was devised for obtaining rate laws and kinetic parameters which describe the thermal degradation of plastics from TGA data, based on the inter-comparison of experiments which were performed at different linear rates of heating.
Abstract: A technique was devised for obtaining rate laws and kinetic parameters which describe the thermal degradation of plastics from TGA data. The method is based on the inter-comparison of experiments which were performed at different linear rates of heating. By this method it is possible to determine the activation energy of certain professes without knowing the form of the kinetic equation. This technique was applied to fiberglass-reinforced CTL 91-LD phenolic resin, where the rate law - (1/we)(dw/dt) = 1018e−55,000/RT [(w - wf)/w0,]5, nr.−1, was found to apply to a major part of the degradation. The equation was successfully tested by several techniques, including a comparison with constant temperature data that were available in the literature. The activation energy was thought to be correct within 10 kcal.

3,002 citations