Kinetic Study and Thermal Decomposition Behavior of Lignite Coal

Abstract

A thermogravimetric analyzer was employed to investigate the thermal behavior and extract the kinetic parameters of Canadian lignite coal. The pyrolysis experiments were conducted in temperatures ranging from 298 K to 1173 K under inert atmosphere utilizing six different heating rates of 1, 6, 9, 12, 15, and 18 K min −1 , respectively. There are different techniques for analyzing the kinetics of solid-state reactions that can generally be classified into two categories: model-fitting and model-free methods. Historically, model-fitting methods are broadly used in solid-state kinetics and show an excellent fit to the experimental data but produce uncertain kinetic parameters especially for nonisothermal conditions. In this work, different model-free techniques such as the Kissinger method and the isoconversional methods of Ozawa, Kissinger-Akahira-Sunose, and Friedman are employed and compared in order to analyze nonisothermal kinetic data and investigate thermal behavior of a lignite coal. Experimental results showed that the activation energy values obtained by the isoconversional methods were in good agreement, but Friedman method was considered to be the best among the model-free methods to evaluate kinetic parameters for solid-state reactions. These results can provide useful information to predict kinetic model of coal pyrolysis and optimization of the process conditions.

Mechanism and kinetics of thermal degradation of insulating materials developed from cellulose fiber and fire retardants

“…However, the differential method of Friedman can eliminate this error. Thus, the Friedman method can be regarded as the best method to evaluate the kinetic parameters compared with other model-free methods such as KAS and FWO [31][32][33][34]. For SYIM and EGIM, the activation energy varied significantly at the higher degree of conversions, indicating the existence of a complex multi-step mechanism including parallel, competitive, and consecutive reactions and activation energies [35].…”

Thermal Characterisation Study of Two Disposable Diaper Brands

“…The final devolatilisation zone is observed where the fixed carbon and ash are released. According to Heydari et al (2015), the lower devolatilisation rates observed can attribute to further gasification and char released at elevated temperatures.…”

“…In this study, kinetic pyrolysis is applied to the two most dominant disposable diaper brands in South Africa (Huggies and Pampers) in order to assess their potential of waste-to-energy production. Pyrolysis involves the thermochemical treatment of samples in the absence of oxygen at elevated temperatures, and during this process, multiple reactions occur, (Apaydin-Varol et al, 2014, Heydari et al, 2015, Perera and Narayana, 2018. In addition, pyrolysis is also known for its production of pyro-gas, pyro-oil, and pyro-char (Heydari et al, 2015).…”

“…Pyrolysis involves the thermochemical treatment of samples in the absence of oxygen at elevated temperatures, and during this process, multiple reactions occur, (Apaydin-Varol et al, 2014, Heydari et al, 2015, Perera and Narayana, 2018. In addition, pyrolysis is also known for its production of pyro-gas, pyro-oil, and pyro-char (Heydari et al, 2015). Furthermore, Aboulkas et al (2010Aboulkas et al ( :1363 highlighted that, "the first step for a suitable design of any polymer reactor is knowledge of the kinetics."…”

Development and Particle Scale Modeling of Metal Oxide Oxygen Carriers in Chemical Looping Applications

“…By plotting ln(t) with respect to 1/T, the activation energy can be obtained for a given value of from the slope of the regression line if at least three isothermal temperatures are explored. The application of this approach provides a means of estimating the overall activation energy associated with the process [99].…”