The mathematical incorrectness of the integral isoconversional methods in case of variable activation energy and the consequences

Šimon, Peter; Thomas, Paul; Dubaj, Tibor; Cibulková, Zuzana; Peller, András; Veverka, Miroslav

doi:10.1007/s10973-013-3459-7

Cited by 70 publications

(33 citation statements)

References 21 publications

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“…Actually, the physical meaning of apparent activation energy remains somewhat ill-defined, thus no conclusions could be drawn. The emphasis is to estimate the modeled physical quantities [34]. The conversion rate of pine sawdust was 0.05-0.8 at apparent activation energy of 134-190 kJ mol -1 , which was consistent with previous reports [35].…”

Section: Pyrolysis Kineticssupporting

confidence: 88%

Co-pyrolysis behaviors and kinetics of sewage sludge and pine sawdust blends under non-isothermal conditions

Zhu

Chen

Xiao

et al. 2014

J Therm Anal Calorim

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Mixing of sewage sludge with classical biomass, such as pine sawdust, can compensate the weaknesses of one fuel by another. The pyrolytic characteristics of sewage sludge (SS), pine sawdust (PS), and their blends were investigated under nitrogen atmosphere by dynamic thermogravimetric analysis at three heating rates of 10, 20, and 30 K min -1 . Three thermal stages (dehydration, devolatilization, further carbonization) were identified during the pyrolysis of single materials, as well as the blends. Blending of PS with SS can improve the devolatilizaion properties of SS, whereas the initial decomposition temperature increases with the increase in proportion of PS. It has been found that the pyrolytic characteristics of the blends can be estimated from those of parent fuels, suggesting that no significant synergistic effect existed during thermal degradation of PS/SS blends. The dependence of apparent activation energy on conversion obtained by Friedman method and distributed activation energy model (DAEM) revealed that the blends can be considered as multistage process. The results indicated that the DAEM can provide reasonable fits to the experimental data.

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Section: Pyrolysis Kineticssupporting

confidence: 88%

Co-pyrolysis behaviors and kinetics of sewage sludge and pine sawdust blends under non-isothermal conditions

Zhu

Chen

Xiao

et al. 2014

J Therm Anal Calorim

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“…[7] The kinetic parameters of complex condensed-phase processes only rarely bear a simple physical or mechanistic meaning. [10] The problems with conversion-dependent kinetic parameters are addressed by the application of incremental isoconversional methods. In such a case, the aforementioned smoothing of the E(a) dependence is of low practical importance.…”

Section: Introductionmentioning

confidence: 99%

An incremental isoconversional method for kinetic analysis based on the orthogonal distance regression

2014

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The parameters obtained from a kinetic analysis of thermoanalytical data often exhibit a conversion-dependent behavior. A novel incremental isoconversional method able to deal with this phenomenon is proposed. The kinetic model is directly fitted to the experimental data using nonlinear orthogonal least squares procedure. The data are processed without transformations, so their error distribution is preserved. As the objective function is based on a maximum likelihood approach, reliable uncertainties of the parameters can be estimated. In contrast to other methods, the activation energy and the pre-exponential factor are treated as equally important kinetic parameters and are estimated simultaneously. Validity of the method is verified on simulated data, including a dataset with local nonlinearity in the temperature variation. A practical application on the nonisothermal cold crystallization of polyethylene terephthalate is presented.

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“…Well-known recommendations for performing kinetic computations on thermal analysis data [27,28] were used; new studies on non-isothermal kinetics were taken into account [29,30].…”

Section: Kinetic Analysis Under Non-isothermal Conditionsmentioning

confidence: 99%

Reactivity in combustion process for expanded graphites: influence of dimensional effect

Логвиненко¹,

Makotchenko²,

Федоров³

2016

Nanosystems: Phys. Chem. Math.

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Thermal stability in combustion reaction for natural graphite, graphene and several expanded graphite phases were studied; the kinetic parameters of the oxidation reaction were calculated for two samples. Natural graphite (crystalline particles 200 -300 µm) has the maximum stability (E 1 = 201 ± 2 kJ/mol, lg A 1 = 7.1 ± 0.1), while multilayer graphene is the most reactive (E 2 = 120 ± 1 kJ mol −1 , lg A 2 = 4.3 ± 0.10). The different sample grain sizes and their different structures result in different thermal stabilities: both in the reaction zones location (i.e. in the topochemical equation forms), and in the kinetic parameters' values.

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The mathematical incorrectness of the integral isoconversional methods in case of variable activation energy and the consequences

Cited by 70 publications

References 21 publications

Co-pyrolysis behaviors and kinetics of sewage sludge and pine sawdust blends under non-isothermal conditions

Co-pyrolysis behaviors and kinetics of sewage sludge and pine sawdust blends under non-isothermal conditions

An incremental isoconversional method for kinetic analysis based on the orthogonal distance regression

Reactivity in combustion process for expanded graphites: influence of dimensional effect

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