Precision of integral methods for the determination of the kinetic parameters

Cai, Junmeng; Liu, R. H.

doi:10.1007/s10973-007-8328-9

Cited by 14 publications

(4 citation statements)

References 18 publications

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“…A series expansion that is among the most accurate of the rational expressions − when truncated to first order is, …”

Section: Approachmentioning

confidence: 99%

Isokinetics

Lyon

2019

J. Phys. Chem. A

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The study of the rates of chemical reactions and their relationship to temperature began in the 19th century with empirical measurements of the time required to reach a particular reaction end point at a constant temperature. By the mid-20th century, the theory of reaction rates had advanced and instruments had been developed in which the temperature of the sample could be increased at a constant rate. These nonisothermal methods are now widely used to determine the kinetic parameters of reactions because of their convenience. In this paper, the mathematical relationship between measurements at constant temperature (isothermal) and constant heating rate (nonisothermal) is developed and it is shown that there is a point in the temperature history of a single-step reaction at which the isothermal and nonisothermal reaction rates are equal. This equal (iso) kinetic point occurs at a temperature early in the heating history of nonisothermal analyses at which the reaction rate begins to accelerate. The isokinetic temperature is the basis for a new method of nonisothermal kinetic analysis that provides a direct measurement of the Arrhenius frequency factor A and activation energy E a for the elementary step of a solid-state reaction without any assumptions about the relationship between these parameters (i.e., kinetic compensation) or the reaction mechanism.

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“…A series expansion that is among the most accurate of the rational expressions − when truncated to first order is, …”

Section: Approachmentioning

confidence: 99%

Isokinetics

Lyon

2019

J. Phys. Chem. A

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“… a Calculated according to eq , γ = E / R T 0 = 10.171, ζ = T / T 0 ≈ T α=0.5 / T 0 = 1.403. b Calculated according to eq 17 in ref , x = E / R T ≈ E / R T α=0.5 = 7.249. …”

Section: Resultsmentioning

confidence: 99%

“…Taking into account that the Coats and Redfern method is so extensively used and that there is some controversy about its precision, it would be of interest to estimate the precision of the Coats and Redfern method for the determination of the activation energy. Some researchers have performed some related studies. – In the papers of Pérez-Maqueda et al, , the systematic analysis of the relative error of the activation energy obtained from the modified Coats and Redfern approach has been carried out. Cai and Liu have analyzed the precision of the activation energy calculated by the Coats and Redfern method.…”

Section: Introductionmentioning

confidence: 99%

“…Some researchers have performed some related studies. – In the papers of Pérez-Maqueda et al, , the systematic analysis of the relative error of the activation energy obtained from the modified Coats and Redfern approach has been carried out. Cai and Liu have analyzed the precision of the activation energy calculated by the Coats and Redfern method. However, in their calculations, the low-temperature end of the temperature integral has been neglected.…”

Section: Introductionmentioning

confidence: 99%

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Precision of the Coats and Redfern Method for the Determination of the Activation Energy without Neglecting the Low-Temperature End of the Temperature Integral

Cai

2008

Energy Fuels

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The Coats and Redfern method for the determination of the activation energy has been extensively used in the kinetic analysis of thermal decomposition of coal and biomass. The relative errors involved in the apparent activation energy obtained from the Coats and Redfern method have been calculated by some researchers. However, in their calculations, the low-temperature end of the temperature integral was neglected. In this study, the precision of the Coats and Redfern method for the determination of the activation energy without neglecting the low-temperature end of the temperature integral has been obtained by means of some theoretical derivation and numerical calculations. The obtained results indicate that there is a significant influence of two dimensionless quantities γ ) E/RT 0 (a dimensionless activation energy, where E is the activation energy, R is the gas constant, and T 0 is the starting temperature of the reaction) and ζ ) T/T 0 (the normalized temperature, where T is the temperature) on the calculated activation energy values. Our results have been verified for simulated data as well as for the non-isothermal data of lignin pyrolysis.

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Non-isothermal kinetics in solids

Cai

Liu

2008

J Therm Anal Calorim

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Precision of integral methods for the determination of the kinetic parameters

Cited by 14 publications

References 18 publications

Isokinetics

Isokinetics

Precision of the Coats and Redfern Method for the Determination of the Activation Energy without Neglecting the Low-Temperature End of the Temperature Integral

Non-isothermal kinetics in solids

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