Isoconversional Kinetic Analysis of Pyrolysis of Sugarcane Bagasse

2012 ◽  
Vol 727-728 ◽  
pp. 1830-1835 ◽  
Author(s):  
Kássia Graciele dos Santos ◽  
Ricardo A. Malagoni ◽  
Taisa S. Lira ◽  
Valéria V. Murata ◽  
Marcos A.S. Barrozo
Keyword(s):  
Activation Energy ◽  
Kinetic Study ◽  
Kinetic Analysis ◽  
Heating Rate ◽  
Sugarcane Bagasse ◽  
Isoconversional Methods ◽  
The Other ◽  
Isoconversional Kinetic Analysis

This paper presents a kinetic study of pyrolysis of sugarcane bagasse from dynamic thermogravimetric experiments (TG). The methods of Kissinger, Ozawa, Starink, Kissinger-Akahira-Sunose and Friedman were used to estimate the activation energy. These methods consider the temperature shifts with increase of heating rate for a given conversion in dynamic TG tests. The activation energy values obtained by the isoconversional methods were in a range 182.8 192.4 kJ·mol-1, values very close to the other biomasses presented by literature.

scholarly journals Advanced Isoconversional Kinetic Analysis for the Elucidation of Complex Reaction Mechanisms: A New Method for the Identification of Rate-Limiting Steps

Molecules ◽  
2019 ◽  
Vol 24 (9) ◽  
pp. 1683 ◽  
Author(s):  
Nicolas Sbirrazzuoli
Keyword(s):  
Activation Energy ◽  
Kinetic Analysis ◽  
Single Step ◽  
Thermoanalytical Techniques ◽  
Diffusion Controlled ◽  
Physical Transformation ◽  
Exponential Factors ◽  
Isoconversional Kinetic Analysis ◽  
The Individual ◽  
Rate Limiting

Two complex cure mechanisms were simulated. Isoconversional kinetic analysis was applied to the resulting data. The study highlighted correlations between the reaction rate, activation energy dependency, rate constants for the chemically controlled part of the reaction and the diffusion-controlled part, activation energy and pre-exponential factors of the individual steps and change in rate-limiting steps. It was shown how some parameters computed using Friedman’s method can help to identify change in the rate-limiting steps of the overall polymerization mechanism as measured by thermoanalytical techniques. It was concluded that the assumption of the validity of a single-step equation when restricted to a given α value holds for complex reactions. The method is not limited to chemical reactions, but can be applied to any complex chemical or physical transformation.

scholarly journals Activation Energies and Temperature Dependencies of the Rates of Crystallization and Melting of Polymers

Polymers ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1070 ◽  
Author(s):  
Sergey Vyazovkin
Keyword(s):  
Experimental Data ◽  
Phase Transition ◽  
Activation Energy ◽  
Temperature Dependence ◽  
Kinetic Analysis ◽  
Review Paper ◽  
Isoconversional Methods ◽  
Activation Energies ◽  
Phase Transition Kinetics ◽  
Kinetic Treatment

The objective of this review paper is to survey the phase transition kinetics with a focus on the temperature dependence of the rates of crystallization and melting, as well as on the activation energies of these processes obtained via the Arrhenius kinetic treatment, including the treatment by isoconversional methods. The literature is analyzed to track the development of the basic models and their underlying concepts. The review presents both theoretical and practical considerations regarding the kinetic analysis of crystallization and melting. Both processes are demonstrated to be kinetically complex, and this is revealed in the form of nonlinear Arrhenius plots and/or the variation of the activation energy with temperature. Principles which aid one to understand and interpret such results are discussed. An emphasis is also put on identifying proper computational methods and experimental data that can lead to meaningful kinetic interpretation.

scholarly journals Determining Preexponential Factor in Model-Free Kinetic Methods: How and Why?

Molecules ◽  
2021 ◽  
Vol 26 (11) ◽  
pp. 3077
Author(s):  
Sergey Vyazovkin
Keyword(s):  
Activation Energy ◽  
Kinetic Analysis ◽  
Rate Constant ◽  
Condensed Phase ◽  
Compensation Effect ◽  
Preexponential Factor ◽  
Isoconversional Methods ◽  
Activation Entropy ◽  
Model Free ◽  
Kinetics Of

The kinetics of thermally stimulated processes in the condensed phase is commonly analyzed by model-free techniques such as isoconversional methods. Oftentimes, this type of analysis is unjustifiably limited to probing the activation energy alone, whereas the preexponential factor remains unexplored. This article calls attention to the importance of determining the preexponential factor as an integral part of model-free kinetic analysis. The use of the compensation effect provides an efficient way of evaluating the preexponential factor for both single- and multi-step kinetics. Many effects observed experimentally as the reaction temperature shifts usually involve changes in both activation energy and preexponential factor and, thus, are better understood by combining both parameters into the rate constant. A technique for establishing the temperature dependence of the rate constant by utilizing the isoconversional values of the activation energy and preexponential factor is explained. It is stressed that that the experimental effects that involve changes in the preexponential factor can be traced to the activation entropy changes that may help in obtaining deeper insights into the process kinetics. The arguments are illustrated by experimental examples.

scholarly journals Thermal Decomposition Study of Ferrocene [(C5H5)2Fe]

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Ashis Bhattacharjee ◽  
Amlan Rooj ◽  
Debasis Roy ◽  
Madhusudan Roy
Keyword(s):  
Activation Energy ◽  
Thermal Decomposition ◽  
Heating Rate ◽  
Isoconversional Methods ◽  
Thermal Reaction ◽  
Single Step ◽  
Model Free ◽  
Probable Reaction ◽  
Single Heating ◽  
Made In

A single-step thermal decomposition of ferrocene [(C5H5)2Fe] using nonisothermal thermogravimetry (TG) has been studied using single- as well as multiple-heating rate programs. Both mechanistic and nonmechanistic methods have been used to analyze the TG data to estimate the kinetic parameters for the solid state reaction. Two different isoconversional methods (improved iterative method and model-free method) have been employed to analyze the TG results to find out whether the activation energy of the reaction depends on the extent of decomposition and to predict the most probable reaction mechanism of thermal decomposition as well. A comparison of the activation energy values for the single-step thermal reaction of ferrocene estimated by different methods has been made in this work. An appraisal on the applicability of single-heating rate data for the analysis of single-step thermal decompositions over the recommendations by the International Confederation for Thermal Analysis and Calorimetry (ICTAC) is made to look beyond the choice.

scholarly journals Leaching of Silver and Gold Contained in a Sedimentary Ore, Using Sodium Thiosulfate; A Preliminary Kinetic Study

Metals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 159 ◽  
Author(s):  
Edmundo Roldán-Contreras ◽  
Eleazar Salinas-Rodríguez ◽  
Juan Hernández-Ávila ◽  
Eduardo Cerecedo-Sáenz ◽  
Ventura Rodríguez-Lugo ◽  
...  
Keyword(s):  
Activation Energy ◽  
Kinetic Study ◽  
Low Temperatures ◽  
Chemical Control ◽  
Reaction Order ◽  
Sodium Thiosulfate ◽  
The Other ◽  
Gold Leaching ◽  
Leaching Process ◽  
Thiosulfate Concentration

Some sedimentary minerals have attractive contents of gold and silver, like a sedimentary exhalative ore available in the eastern of Hidalgo in Mexico. The gold and silver contained represent an interesting opportunity for processing by non-toxic and aggressive leaching reagents like thiosulfate. The preliminary kinetic study indicated that the leaching process was poorly affected by temperature and thiosulfate concentration. The reaction order was −0.61 for Ag, considering a thiosulfate concentration between 200–500 mol·m−3, while, for Au, it was −0.09 for a concentration range between 32–320 mol·m–3. By varying the pH 7–10, it was found that the reaction order was n = 5.03 for Ag, while, for Au, the value was n = 0.94, considering pH 9.5–11. The activation energy obtained during the silver leaching process was 3.15 kJ·mol−1 (298–328 K), which was indicative of a diffusive control of the process. On the other hand, during gold leaching, the activation energy obtained was of 36.44 kJ·mol−1, which was indicative that this process was mixed controlled process, first at low temperatures by diffusive control (298–313 K) and then by chemical control (318–323 K).

scholarly journals Kinetic analysis of co-combustion of microalgae spirulina platensis and synthetic waste through the fitting model

2018 ◽  
Vol 204 ◽  
pp. 00009 ◽  
Author(s):  
Sukarni Sukarni ◽  
Ardianto Prasetiyo ◽  
Sumarli Sumarli ◽  
Imam Muda Nauri ◽  
Avita Ayu Permanasari
Keyword(s):  
Activation Energy ◽  
Thermal Degradation ◽  
Kinetic Analysis ◽  
Heating Rate ◽  
Spirulina Platensis ◽  
Thermogravimetric Analyzer ◽  
Second Stage ◽  
Air Atmosphere ◽  
Three Stages ◽  
Fitting Model

Thermogravimetric analyzer had been occupied to investigate the behavior of co-combustion between microalgae Spirulina platensis and synthetic waste. The powder of microalgae and synthetic waste were mixed in the same ratio of 50/50. Around 10 mg of the sample was heated up in the chamber under air atmosphere flowrate of 100 ml/min at a heating rate of 10 °C/min. The results showed that the sample blend is undergoing thermal degradation in the three stages. The most massive reaction occurred in the second stage in which around 74% of the mass degraded and combusted. The activation energy in the main combustion reaction zone according to the method of Horowitz–Metzger was 57.77 kJ/mol.

Kinetic study of (Bi,Pb)2Sr2Ca2Cu3O10+x phase formation in KCl flux

2002 ◽  
Vol 17 (9) ◽  
pp. 2281-2285 ◽  
Author(s):  
Sergey Lee ◽  
Ayako Yamamoto ◽  
Setsuko Tajima
Keyword(s):  
Activation Energy ◽  
Phase Transformation ◽  
Kinetic Study ◽  
Kinetic Analysis ◽  
Phase Formation ◽  
Single Phase ◽  
Avrami Exponent ◽  
Whole Process ◽  
Kinetics Of

The kinetics of (Bi,Pb)2Sr2Ca2Cu3O10+x phase formation in KCl flux was studied, and kinetic analysis using the Avrami relation for isothermal phase transformation gave the Avrami exponent n = 2.5 at 855 °C for the whole process of (Bi,Pb)-2223 phase formation. The estimated value of the activation energy Ea = 150 kJ/mol for the formation of (Bi,Pb)-2223 phase at 845–855 °C is the lowest among the previously reported values. The low value of activation energy explains the fast formation of single-phase (Bi,Pb)-2223 powder in the KCl flux.

Kinetic Analysis of the Decomposition of Calcium Carbonate Using Danyang Limestone

2006 ◽  
Vol 510-511 ◽  
pp. 502-505 ◽  
Author(s):  
Sang Hwan Cho ◽  
Sung Min Joo ◽  
Jin Sang Cho ◽  
Young Hwan Yu ◽  
Ji Whan Ahn ◽  
...  
Keyword(s):  
Activation Energy ◽  
Calcium Carbonate ◽  
Kinetic Parameter ◽  
Kinetic Analysis ◽  
Heating Rate ◽  
Reaction Rate ◽  
Decomposition Temperature ◽  
Final Point ◽  
Maximum Reaction

Non-isothermal behaviors of calcium carbonate using Danyang limestone were investigated. It was attempted to provide non-isothermal data with a precision sufficient for the determination of reliable decomposition behaviors and for the estimation of accurate kinetic parameter. The decomposition temperature of calcium carbonate on the onset, peak and final point were measured. Reaction rate was decreased and maximum reaction temperature was increased with increasing heating rate. Activation energy of Danyang limestone was 45.14㎉/㏖ and 50.80㎉/ ㏖ by Kissinger method and Freeman method, respectively.

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