On the accuracy and precision of estimation of the activation energy of non-isothermal decomposition of a solid

Leyko, J.; Maciejewski, Marek; Szuniewicz, R.

doi:10.1007/bf01914018

Cited by 18 publications

(3 citation statements)

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“…8 A differential method developed by Anderson and Friedman. 9 In this method the experimental data must be differentiated for the kinetic determinations and the experiments were performed at different heating rates. For experimental data that are grouped with respect to the values a j of the conversion degree, taken from thermal curves recorded at different heating rates, equation (1) assumes the following form…”

Section: Introductionmentioning

confidence: 99%

Overall kinetic study of non-isothermal decomposition of calcium carbonate

Ioannou¹,

Zoumpoulakis²,

Halikia³

et al. 2009

Mineral Processing and Extractive Metallurgy

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The present paper is a comparative study of six different non-isothermal methods of kinetic analysis for the determination of the mechanism of the thermal decomposition of CaCO 3 from thermogravimetric experiments. The whole experiment was carried out in a thermogravimetric analyser with nitrogen atmosphere up to 1100uC and at five different heating rates, i.e. 5, 10, 20, 30 and 40 K min 21 . Applying each of these methods, the kinetic parameters of the reaction are evaluated and an assessment is made for the kinetic model that best represents the mechanism of the decomposition. The mean value of the activation energy under continuous flow of nitrogen is E5176?32176?4 kJ mol 21 . The value of the pre-exponential factor is ln (A mean /s 21 )513?7 according to model dependent methods and the phase boundary controlled reaction of cylindrical geometry is the kinetic model, which describes best the calcium carbonate decomposition. List of symbolsA pre-exponential factor, s 21 A li pre-exponential factor at different kinetic models l and at different heating rates i, s 21 A a pre-exponential factor at specific conversion degree a, s 21 E activation energy, kJ mol 21 E j activation energy at the conversion degree a j E li activation energy at different kinetic models l and at different heating rates i, kJ mol 21 E a activation energy at specific conversion degree a, kJ mol 21 f(a) representative function of the actual reaction mechanism g(a) integrated form of f(a) K ni kinetic constant R universal gas constant, kJ mol 21 K 21 t time, s T temperature, K T o initial temperature, K T ij temperature where i denotes the sequential thermal curve, j the reading of da/dt and T at a time when a5a j , K T a temperature at specific conversion degree a, K T a i or q temperature at specific conversion degree a and at different heating rates i,q where q5iz1, K a degree of conversion b heating rate, K mol 21 b i different heating rates i, K mol 21 b i or q different heating rates i,j where q5iz1, K mol 21

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Section: Introductionmentioning

confidence: 99%

Overall kinetic study of non-isothermal decomposition of calcium carbonate

Ioannou¹,

Zoumpoulakis²,

Halikia³

et al. 2009

Mineral Processing and Extractive Metallurgy

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“…Determination of the activation energy vs. weight loss [2] By expressing the conversion degree in the kinetic Eq. (9) …”

Section: Determination Of the Kinetic Model Parameters And Structurementioning

confidence: 99%

Determination of the kinetic parameters of the multi-stage thermal decomposition of solids under non-isothermal conditions by the non-linear estimation approach

Leyko¹,

Maciejewski

Szuniewicz³

1979

Journal of Thermal Analysis

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The activation energy of decomposition of alurniniurn hydroxide vs. weight loss was estimated from thermogravirnetric data collected over a wide range of heating rates, without resorting to the model of the reaction mechanism.These activation energy values were subsequently used to distinguish individual dehydration stages and to determine the best models of the reaction kinetics for these stages.Finally, the overall decomposition model was formulated, and its parameters were determined by the non-linear estimation approach.Owing to the development of numerical, computer-based identification method, derivation of a model for the multi-stage thermal decomposition of a solid has become a greatly simplified task [1 ]. However, a suitable procedure for processing of experimental data to obtain the most information possible on the individual decomposition stages remains of significance. Such a procedure should help to establish a preliminary model structure and determine the activation energy values for the individual stages.Here, a method is advanced for determining the activation energy and the model structure for the individual thermal decomposition stages, and for develoifing a kinetic model of overall decomposition that would most accurately account for the, experimental data over a wide range of experimental conditions. TheoreticalIn the multi-stage thermal decomposition of a solid under increasing temperature it often happens that the successive stages of the process overlap rather than proceed separately.Depending on the decomposition mechanism involved, the chemical reactions corresponding to the individual stages can occur either consecutively or simultaneously.

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“…The data for heating rates of 2.3, 7.4 and 14.8 deg/min were taken from the literature [7] and those for the heating rate of 10 deg/min have been obtained by means of a Derivatograph Q 1500 D, Paulik-Paulik-Erdey type.…”

Section: Introductionmentioning

confidence: 99%

A comparison of some integral methods

Popescu¹,

Segal

Oprea

1992

Journal of Thermal Analysis

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The integral methods proposed to compute the kinetic pararoeters of heterogeneous reactions under non-isothermal conditions are usually worked byY~he help of the least squares method and the obtained correlation coefficient is taken as a criterion to choose the best integral method.An analysis of several experimental data by mean of three different integral methods was performed by us and the results pointed out that this criterion, by itself, is not enough to provide reliable information on the kinetic parameters.It appears, thus, that the use of an integral method or another is a simple matter of researcher's choice.

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On the accuracy and precision of estimation of the activation energy of non-isothermal decomposition of a solid

Cited by 18 publications

References 5 publications

Overall kinetic study of non-isothermal decomposition of calcium carbonate

Overall kinetic study of non-isothermal decomposition of calcium carbonate

Determination of the kinetic parameters of the multi-stage thermal decomposition of solids under non-isothermal conditions by the non-linear estimation approach

A comparison of some integral methods

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