scholarly journals Kinetic analysis of the pyrolysis of apricot stone and its main components via distributed activation energy mode

BioResources ◽  
2020 ◽  
Vol 15 (1) ◽  
pp. 1187-1204
Author(s):  
Huanhuan Ma ◽  
Yimeng Zhang ◽  
Liangcai Wang ◽  
Zhengxiang Zhu ◽  
Yu Chen ◽  
...  
Keyword(s):  
Activation Energy ◽  
Energy Distribution ◽  
Apparent Activation Energy ◽  
Early Stage ◽  
Conversion Degree ◽  
Heating Rates ◽  
Continuous Increase ◽  
Thermogravimetric Analyzer ◽  
Energy Mode ◽  
Main Components

The kinetics of pyrolysis of apricot stone and its main components, i.e., lignin, cellulose, and hemicellulose, were investigated via distributed activation energy mode. Experiments were done in a thermogravimetric analyzer at heating rates of 10, 20, 30, and 40 K·min-1 under nitrogen. The activation energy distribution peaks for the apricot stone, lignin, cellulose, and hemicellulose were centered at 246, 318, 364, and 170 kJ·mol-1, respectively. The activation energy distribution for the apricot stone slightly changed; lignin exhibited the widest distribution; and cellulose exhibited the highest activation energy at a conversion degree (α) of less than 0.75. At low pyrolysis temperatures (400 K to 600 K), the pyrolysis of hemicellulose was the main pyrolysis reaction. The apparent activation energy for the apricot stone mainly depended on the pyrolysis of hemicellulose and a small amount of lignin, and the activation energy was low in the early stage of pyrolysis. With the continuous increase in the pyrolysis temperatures (600 K to 660 K), the thermal weight loss of cellulose and lignin was intense. The apparent activation energy for the apricot stone mainly resulted from the pyrolysis of cellulose and lignin, and a higher activation energy was observed in the later stage of pyrolysis.

scholarly journals Thermally stimulated oxygen desorption in Sr2FeMoO6-δ

2018 ◽  
Vol 4 (1) ◽  
pp. 1-5 ◽  
Author(s):  
Nikolay A. Kalanda
Keyword(s):  
Activation Energy ◽  
Oxygen Diffusion ◽  
Gas Flow ◽  
Oxygen Vacancies ◽  
Early Stage ◽  
Diffusion Activation Energy ◽  
Energy Calculation ◽  
Heating Rates ◽  
Oxygen Desorption ◽  
Diffusion Activation

Polycrystalline Sr2FeMoO6-δ specimens have been obtained by solid state synthesis from partially reduced SrFeO2,52 and SrMoO4 precursors. It has been shown that during oxygen desorption from the Sr2FeMoO6-δ compound in polythermal mode in a 5%H2/Ar gas flow at different heating rates, the oxygen index 6-δ depends on the heating rate and does not achieve saturation at T = 1420 K. Oxygen diffusion activation energy calculation using the Merzhanov method has shown that at an early stage of oxygen desorption from the Sr2FeMoO6-δ compound the oxygen diffusion activation energy is the lowest Еа = 76.7 kJ/mole at δ = 0.005. With an increase in the concentration of oxygen vacancies, the oxygen diffusion activation energy grows to Еа = 156.3 kJ/mole at δ = 0.06. It has been found that the dδ/dt = f (Т) and dδ/dt = f (δ) functions have a typical break which allows one to divide oxygen desorption in two process stages. It is hypothesized that an increase in the concentration of oxygen vacancies Vo•• leads to their mutual interaction followed by ordering in the Fe/Mo-01 crystallographic planes with the formation of various types of associations.

A Kinetic Study of Wetland Plant Suaeda salsa L. Pyrolysis Using Thermogravimetric Analyzer

2013 ◽  
Vol 848 ◽  
pp. 126-130
Author(s):  
Hua Xiao Yan ◽  
Hui Zhao ◽  
Qi Liu ◽  
Yan Xiang Ai ◽  
Yan Zhang ◽  
...  
Keyword(s):  
Activation Energy ◽  
Three Dimensional ◽  
Nitrogen Atmosphere ◽  
Suaeda Salsa ◽  
Good Prospect ◽  
Heating Rates ◽  
Thermogravimetric Analyzer ◽  
Exponential Factors ◽  
Pyrolysis Feedstock ◽  
Diffusion Function

The Suaeda salsa L. has been discovered to be a great potential as a new kind of renewable energy. The pyrolytic characteristics and kinetics of S. salsa were investigated at heating rates of 5, 10, 20, 30°C/min under nitrogen atmosphere respectively. The most probable mechanism function was deduced using Popescu method, which is a three-dimensional diffusion function (), and n=-2/3. Activation energy and pre-exponential factors were studied through the FWO, KAS and Popescu methods. The results showed that the activation energy increase as the pyrolysis process and three stages were observed in the TG-DTG curves of S.salsa. The results showed that S.salsa as a pyrolysis feedstock has a great potential and a good prospect in bio-oil production.

scholarly journals Thermally stimulated oxygen desorption in Sr2FeMoO6-δ

2019 ◽  
Vol 21 (1) ◽  
pp. 48-53
Author(s):  
N. A. Kalanda
Keyword(s):  
Activation Energy ◽  
Oxygen Diffusion ◽  
Gas Flow ◽  
Oxygen Vacancies ◽  
Early Stage ◽  
Diffusion Activation Energy ◽  
Energy Calculation ◽  
Heating Rates ◽  
Oxygen Desorption ◽  
Diffusion Activation

Polycrystalline Sr2FeMoO6-δ specimens have been obtained by solid state synthesis from partially reduced SrFeO2.52 and SrMoO4 precursors. It has been shown that during oxygen desorption from the Sr2FeMoO6-δ compound in polythermal mode in a 5%H2/Ar gas flow at different heating rates, the oxygen index 6–δ depends on the heating rate and does not achieve saturation at T = 1420 K. Oxygen diffusion activation energy calculation using the Merzhanov method has shown that at an early stage of oxygen desorption from the Sr2FeMoO6-δ compound the oxygen diffusion activation energy is the lowest Еа = 76.7 kJ/mole at δ = 0.005. With an increase in the concentration of oxygen vacancies, the oxygen diffusion activation energy grows to Еа = 156.3 kJ/mole at δ = 0.06. It has been found that the dδ/dt = f(Т) AND dδ/dt = f(δ) functions have a typical break which allows one to divide oxygen desorption in two process stages. It is hypothesized that an increase in the concentration of oxygen vacancies V ·· leads to their mutual interaction followed by ordering in the Fe/Mo–O1 crystallographic planes with the formation of various types of associations.

scholarly journals Thermodynamic model and kinetic compensation effect of oil sludge pyrolysis based on thermogravimetric analysis

2020 ◽  
pp. 350-350
Author(s):  
Hui Liu ◽  
Chenglang Xiang ◽  
Jie Mu ◽  
Jieyu Yao ◽  
Dong Ye ◽  
...  
Keyword(s):  
Activation Energy ◽  
Apparent Activation Energy ◽  
Compensation Effect ◽  
Thermodynamic Characteristics ◽  
Oil Sludge ◽  
High Heating Rate ◽  
Thermodynamic Models ◽  
Heating Rates ◽  
Kinetic Compensation Effect ◽  
Exponential Factor

Oil sludge (OS) is an organic solid waste in the petrochemical industry and improper treatment of OS will cause environmental pollution. Pyrolysis is an effective way to realize its resource reuse. In order to understand the pyrolysis behavior and thermodynamic characteristics of OS, four OS samples from storage tanks were used as the research object, and pyrolysis experiments were carried out at heating rates of 5, 10, and 15?/min under a nitrogen atmosphere. The kinetic parameters of pyrolysis of OS are calculated by three equal conversion methods (Friedman method (FR), Flynn-Wall-Ozawa method (FWO) and Distributed activation energy model (DAEM)), and the most possible thermodynamic models for the main pyrolysis phase were analyzed and discussed by introducing the Malek method. The results show: High heating rate can promote the pyrolysis of OS; In the pyrolysis stage, the apparent activation energy increases with the increase of the conversion rate. The apparent activation energy calculated by the FR method is more reliable. The average apparent activation energies of the four OS are 221.23, 84.71, 94.67 and 116.56 kJ/mol, respectively. The apparent activation energy and the pre-exponential factor are positively correlated, indicating that there is a kinetic compensation effect in the pyrolysis process. The thermodynamic models of the four OS samples are all three-dimensional diffusion models, but their integral functions are different. The research results can provide theoretical support for the industrialization, harmlessness and resource utilization of OS pyrolysis.

Pyrolysis Characteristics of Rice Husk Using TG-DTG Analysis

2013 ◽  
Vol 291-294 ◽  
pp. 351-354
Author(s):  
Qing Wang ◽  
Chun Xia Jia ◽  
Hong Peng Liu
Keyword(s):  
Activation Energy ◽  
Rice Husk ◽  
Frequency Factor ◽  
Weight Loss Curve ◽  
Heating Rates ◽  
Pyrolysis Characteristics ◽  
Thermogravimetric Analyzer ◽  
Purge Gas ◽  
Arrhenius Plot Method ◽  
Pyrolysis Kinetic

The rice husk from China has been non-isothermally pyrolysed on thermogravimetric analyzer(TGA). The analyses were performed at different heating rates (20, 40, 60, 80, 100°C/min) up to 900°C with nitrogen as purge gas. The weight loss curve showed that the main pyrolysis of rice husk took place in the range of 200~500°C. On the basis of experiment data, a pyrolysis kinetic model was proposed. The kinetic parameters of activation energy(E) and frequency factor(A) were obtained by the Direct Arrhenius Plot Method. There was no clear relationship between activation energy and heating rate.

scholarly journals Pyrolysis kinetics and thermal decomposition behavior of polycarbonate - a TGA-FTIR study

2014 ◽  
Vol 18 (3) ◽  
pp. 833-842 ◽  
Author(s):  
Esin Apaydin-Varol ◽  
Sevgi Polat ◽  
Ayse Putun
Keyword(s):  
Activation Energy ◽  
Fourier Transform ◽  
Reaction Order ◽  
Fourier Transform Infrared ◽  
Pyrolysis Kinetics ◽  
Heating Rates ◽  
Exponential Factor ◽  
Thermogravimetric Analyzer ◽  
Fourier Transform Infrared Spectrometer ◽  
Infrared Spectrometer

This study covers the thermal degradation of polycarbonate by means of Thermogravimetric Analyzer coupled with Fourier transform infrared spectrometer (TGA-FTIR). Thermogravimetric analysis of polycarbonate was carried out at four different heating rates of 5, 10, 15, and 20?C per minute from 25?C to 1000?C under nitrogen atmosphere. The results indicated that polycarbonate was decomposed in the temperature range of 425-600?C. The kinetic parameters, such as activation energy, pre-exponential factor and reaction order were determined using five different kinetic models; namely Coast-Redfern, Friedman, Kissinger, Flynn-Wall-Ozawa (FWO), and Kissinger-Akahira-Sunose (KAS). Overall decomposition reaction order was determined by Coats-Redfern method as 1.5. Average activation energy was calculated as 150.42, 230.76, 216.97, and 218.56 kJ/mol by using Kissinger, Friedman, FWO, and KAS models, respectively. Furthermore, the main gases released during the pyrolysis of polycarbonate were determined as CO2, CH4, CO, H2O, and other lower molecular weight hydrocarbons such as aldehydes, ketones and carbonyls by using thermogravimetric analyzer coupled with Fourier transform infrared spectrometer.

Decomposition Kinetics of Switchgrass: Estimating Activation Energy

2014 ◽  
Vol 881-883 ◽  
pp. 726-733
Author(s):  
Gui Ying Xu ◽  
Jiang Bo Wang ◽  
Ling Ping Guo ◽  
Guo Gang Sun
Keyword(s):  
Activation Energy ◽  
Thermal Decomposition ◽  
Apparent Activation Energy ◽  
High Purity ◽  
Isoconversional Methods ◽  
Decomposition Kinetics ◽  
Heating Rates ◽  
Model Free ◽  
Chemical Utilization ◽  
Kinetics Of

TG analysis was used to investigate the thermal decomposition of switchgrass, which is a potential gasification feedstock. 10 mg switchgrass sample with the particles between 0.45 and 0.70 mm was linearly heated to 873 K at heating rates of 10, 20, 30 K/min, respectively, under high-purity nitrogen. The Kissinger method and three isoconversional methods including Friedman, Flynn-wall-Ozawa, Vyazovkin and Lenikeocink methods were used to estimate the apparent activation energy of switchgrass. With the three isoconversional methods, it can be concluded that the activation energy increases with increasing conversion. The four model free methods reveal activation energies in the range of 70-460 kJ/mol. These activation energy values provide the basic data for the thermo-chemical utilization of the switchgrass.

Pyrolysis Characteristics of Oil Sands

2012 ◽  
Vol 614-615 ◽  
pp. 111-114 ◽  
Author(s):  
Chun Xia Jia ◽  
Qing Wang ◽  
Xin Yu Zhang ◽  
Yin Wang
Keyword(s):  
Activation Energy ◽  
Oil Sands ◽  
Frequency Factor ◽  
Weight Loss Curve ◽  
Oil Sand ◽  
Heating Rates ◽  
Pyrolysis Characteristics ◽  
Thermogravimetric Analyzer ◽  
Purge Gas ◽  
Pyrolysis Kinetic

Three oil sand samples from Indonesia have been non-isothermally pyrolysed on thermogravimetric analyzer (TGA). The analyses were performed at different heating rates (5, 15 and 25oC/min) up to 850oC with nitrogen as purge gas. The weight loss curve shows that the main pyrolysis of oil sand takes place in the range of 200~600oC. On the basis of experimental data, a pyrolysis kinetic model was proposed. The kinetic parameters of activation energy (E) and frequency factor (A) were obtained by Integral Method. There is no clear relationship between activation energy and heating rate.

scholarly journals Comparison of the dehydration kinetics of solid state compounds of 2-methoxybenzylidenepyruvate with some divalent metal ions

2010 ◽  
Vol 35 (1) ◽  
pp. 7-18
Author(s):  
M. Kobelnik ◽  
C. A. Ribeiro ◽  
D. S. Dias ◽  
G. A. Bernabé ◽  
M. S. Crespi
Keyword(s):  
Activation Energy ◽  
Solid State ◽  
Nitrogen Atmosphere ◽  
Divalent Metal ◽  
Point Of View ◽  
Conversion Degree ◽  
Divalent Metal Ions ◽  
Heating Rates ◽  
Exponential Factor ◽  
Kinetics Of

Divalent metal complexes of ligand 2-methoxybenzylidenepyruvate with Fe, Co, Ni, Cu and Zn as well as sodium salt were synthesized and investigated in the solid state. TG curves of these compounds were obtained with masses sample of 1 and 5mg under nitrogen atmosphere. Different heating rates were used to characterize and study these compounds from the kinetic point of view. The activation energy and pre-exponential factor were obtained applying the Wall-Flynn-Ozawa method to the TG curves. The obtained data were evaluated and the values of activation energy (Ea / kJ mol-1) was plotted in function of the conversion degree (α). The results show that due to mass sample, different activation energies were obtained. The results are discussed mainly taking into account the linear dependence between the activation energy and the pre exponential factor, where was verified the effect of kinetic compensation (KCE) and possible linear relations between the dehydrations steps of these compounds.

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