Kinetic analysis of the thermal decomposition of cellulose: The main step of mass loss

Atmosphere is one of the most significant factors in the thermal decomposition of biomass. In domestic or industrial biomass boilers, ambient oxygen concentration varies through time, which means that the reaction will change from pyrolysis to combustion. In this way, to analyze and compare each thermochemical conversion process, a simple analytical method, the non-isothermal thermogravimetric analysis, is carried out under oxidative (air) and non-oxidative (argon) environments at 10 °C/min and as a function of different flow rates (2 to 150 mL/min). Additionally, this work was complemented by a kinetic analysis considering a first-order reaction to each conversion stage and using the Coats–Redfern method. The effect of the atmosphere on the thermal decomposition behavior was evident. It was observed that the thermal decomposition of pine wood particles varied from three to two stages when the oxidative or inert atmosphere was applied. The presence of oxygen changes the mass loss curve mainly at high temperature, around 350 °C, where char reacts with oxygen. The maximum mass loss rate from experiments with the oxidative atmosphere is 15% higher than in an inert atmosphere, the average char combustion rate is approximately 5 times higher and the heat released reaches levels 3.44 times higher than in an inert atmosphere. Ignition and combustion indexes were also defined, and results revealed that particles are ignited faster under oxidative atmosphere and that, on average, the combustion index is 1.7 times higher, which reinforces the more vigorous way that the samples are burned and how char is burned out faster in the experiments with air. Regarding the kinetics analysis, higher activation energies, and consequently, lower reactivity was obtained under the oxidative atmosphere for the second stage (~125 kJ/mol) and under the inert atmosphere for the third thermal conversion stage (~190 kJ/mol).

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The Kinetic Analysis of Thermal Decomposition of PMMA/MMT Nanocomposites

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.353-358.1366 ◽

2007 ◽

Vol 353-358 ◽

pp. 1366-1369 ◽

Cited By ~ 1

Author(s):

Kui Chen ◽

Rui Chen Yang ◽

S.W. Cheng

Keyword(s):

Activation Energy ◽

Thermal Stability ◽

Thermal Decomposition ◽

Methyl Methacrylate ◽

Mass Loss ◽

Apparent Activation Energy ◽

Kinetic Analysis ◽

Decomposition Kinetics ◽

Ozawa Equation ◽

Thermal Stability Of

The thermal decomposition kinetics and thermal stability of poly (methyl methacrylate) (PMMA) and PMMA/ montmorillonite (MMT) nanocomposites containing 4 wt% MMT were researched by thermogravimetry (TG). The results show that, because of the barrier behavior of exfoliated MMT layer, the temperature of thermal decomposition of PMMA/ MMT nanocomposites is improved by about 10 °C, and thermal stability is improved by about double. The apparent activation energy of decomposition, calculated by Ozawa equation, of nanocomposites is higher than that of PMMA before 27 % mass loss.

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Thermal decomposition of tris(O-ethyldithiocarbonato)-antimony(III)—a single-source precursor for antimony sulfide thin films

Journal of Thermal Analysis and Calorimetry ◽

10.1007/s10973-021-10885-1 ◽

2021 ◽

Author(s):

Jako S. Eensalu ◽

Kaia Tõnsuaadu ◽

Jasper Adamson ◽

Ilona Oja Acik ◽

Malle Krunks

Keyword(s):

Thin Films ◽

Thermal Decomposition ◽

Mass Loss ◽

Solid Phase ◽

Evolved Gas Analysis ◽

Gas Analysis ◽

Thermal Decomposition Mechanism ◽

Product Analysis ◽

Gaseous Species ◽

Single Source Precursor

AbstractThermal decomposition of tris(O-ethyldithiocarbonato)-antimony(III) (1), a precursor for Sb2S3 thin films synthesized from an acidified aqueous solution of SbCl3 and KS2COCH2CH3, was monitored by simultaneous thermogravimetry, differential thermal analysis and evolved gas analysis via mass spectroscopy (TG/DTA-EGA-MS) measurements in dynamic Ar, and synthetic air atmospheres. 1 was identified by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR) measurements, and quantified by NMR and elemental analysis. Solid intermediates and final decomposition products of 1 prepared in both atmospheres were determined by X-ray diffraction (XRD), Raman spectroscopy, and FTIR. 1 is a complex compound, where Sb is coordinated by three ethyldithiocarbonate ligands via the S atoms. The thermal degradation of 1 in Ar consists of three mass loss steps, and four mass loss steps in synthetic air. The total mass losses are 100% at 800 °C in Ar, and 66.8% at 600 °C in synthetic air, where the final product is Sb2O4. 1 melts at 85 °C, and decomposes at 90–170 °C into mainly Sb2S3, as confirmed by Raman, and an impurity phase consisting mostly of CSO 2 2− ligands. The solid-phase mineralizes fully at ≈240 °C, which permits Sb2S3 to crystallize at around 250 °C in both atmospheres. The gaseous species evolved include CS2, C2H5OH, CO, CO2, COS, H2O, SO2, and minor quantities of C2H5SH, (C2H5)2S, (C2H5)2O, and (S2COCH2CH3)2. The thermal decomposition mechanism of 1 is described with chemical reactions based on EGA-MS and solid intermediate decomposition product analysis.

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Kinetic Analysis of the Thermal Decomposition of Iron(III) Phosphates: Fe(NH3)2PO4 and Fe(ND3)2PO4

International Journal of Molecular Sciences ◽

10.3390/ijms21030781 ◽

2020 ◽

Vol 21 (3) ◽

pp. 781

Author(s):

Isabel Iglesias ◽

José A. Huidobro ◽

Belén F. Alfonso ◽

Camino Trobajo ◽

Aránzazu Espina ◽

...

Keyword(s):

Thermal Decomposition ◽

Kinetic Analysis ◽

Room Temperature ◽

Isoconversional Methods ◽

Iron Phosphate ◽

Dihydrogen Phosphate ◽

Monoclinic System ◽

Space Group ◽

X Ray ◽

Group A

The hydrothermal synthesis and both the chemical and structural characterization of a diamin iron phosphate are reported. A new synthetic route, by using n-butylammonium dihydrogen phosphate as a precursor, leads to the largest crystals described thus far for this compound. Its crystal structure is determined from single-crystal X-ray diffraction data. It crystallizes in the orthorhombic system (Pnma space group, a = 10.1116(2) Å, b = 6.3652(1) Å, c = 7.5691(1) Å, Z = 4) at room temperature and, below 220 K, changes towards the monoclinic system P21/n, space group. The in situ powder X-ray thermo-diffraction monitoring for the compound, between room temperature and 1100 K, is also included. Thermal analysis shows that the solid is stable up to ca. 440 K. The kinetic analysis of thermal decomposition (hydrogenated and deuterated forms) is performed by using the isoconversional methods of Vyazovkin and a modified version of Friedman. Similar values for the kinetic parameters are achieved by both methods and they are checked by comparing experimental and calculated conversion curves.

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Thermal decomposition kinetics. XIII. Effect of sample mass on the thermal decomposition kinetics of CaC2O4 · H2O from isothermal mass-loss data

Thermochimica Acta ◽

10.1016/0040-6031(84)80014-3 ◽

1984 ◽

Vol 74 (1-3) ◽

pp. 143-150 ◽

Cited By ~ 24

Author(s):

K.N. Ninan

Keyword(s):

Thermal Decomposition ◽

Mass Loss ◽

Decomposition Kinetics ◽

Thermal Decomposition Kinetics ◽

Sample Mass ◽

Loss Data ◽

Kinetics Of ◽

Isothermal Mass

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Kinetic Analysis of Overlapping Multistep Thermal Decomposition of 2,6-Diamino-3,5-dinitropyrazine-1-oxide (LLM-105)

The Journal of Physical Chemistry C ◽

10.1021/acs.jpcc.8b07817 ◽

2018 ◽

Vol 122 (45) ◽

pp. 25999-26006 ◽

Cited By ~ 4

Author(s):

Qian Yu ◽

Yu Liu ◽

Heliang Sui ◽

Jie Sun ◽

Jinshan Li

Keyword(s):

Thermal Decomposition ◽

Kinetic Analysis

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Study of thermal behavior of phytic acid

Brazilian Journal of Pharmaceutical Sciences ◽

10.1590/s1984-82502013000200009 ◽

2013 ◽

Vol 49 (2) ◽

pp. 275-283 ◽

Cited By ~ 28

Author(s):

André Luis Máximo Daneluti ◽

Jivaldo do Rosário Matos

Keyword(s):

Thermal Decomposition ◽

Thermal Behavior ◽

Mass Loss ◽

Kinetic Study ◽

Phytic Acid ◽

Absorption Spectroscopy ◽

Elemental Analysis ◽

Reaction Order ◽

Dehydration Process ◽

Thermogravimetric Method

Phytic acid is a natural compound widely used as depigmenting agent in galenic cosmetic emulsions. However, we have observed experimentally that phytic acid, when heated to 150 ºC for around one hour, shows evidence of thermal decomposition. Few studies investigating this substance alone with regard to its stability are available in the literature. This fact prompted the present study to characterize this species and its thermal behavior using thermal analysis (TG/DTG and DSC) and to associate the results of these techniques with those obtained by elemental analysis (EA) and absorption spectroscopy in the infrared region. The TG/DTG and DSC curves allowed evaluation of the thermal behavior of the sample of phytic acid and enabled use of the non-isothermal thermogravimetric method to study the kinetics of the three main mass-loss events: dehydration I, dehydration II and thermal decomposition. The combination of infrared absorption spectroscopy and elemental analysis techniques allowed evaluation of the intermediate products of the thermal decomposition of phytic acid. The infrared spectra of samples taken during the heating process revealed a reduction in the intensity of the absorption band related to O-H stretching as a result of the dehydration process. Furthermore, elemental analysis results showed an increase in the carbon content and a decrease in the hydrogen content at temperatures of 95, 150, 263 and 380 °C. Visually, darkening of the material was observed at 150 °C, indicating that the thermal decomposition of the material started at this temperature. At a temperature of 380 °C, thermal decomposition progressed, leading to a decrease in carbon and hydrogen. The results of thermogravimetry coupled with those of elemental analysis allow us to conclude that there was agreement between the percentages of phytic acid found in aqueous solution. The kinetic study by the non-isothermal thermogravimetric method showed that the dehydration process occurred in two stages. Dehydration step I promoted a process of vaporization of water (reaction order of zero), whereas dehydration step II showed an order of reaction equal to five. This change in reaction order was attributed to loss of chemically bonded water molecules of phytic acid or to the presence of volatile substances. Finally, the thermal decomposition step revealed an order of reaction equal to one. It was not possible to perform the kinetic study for other stages of mass loss.

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Flammability and Thermal Kinetic Analysis of UiO-66-Based PMMA Polymer Composites

Polymers ◽

10.3390/polym13234113 ◽

2021 ◽

Vol 13 (23) ◽

pp. 4113

Author(s):

Ruiqing Shen ◽

Tian-Hao Yan ◽

Rong Ma ◽

Elizabeth Joseph ◽

Yufeng Quan ◽

...

Keyword(s):

Thermal Decomposition ◽

Mass Loss ◽

Polymer Composites ◽

Flame Retardants ◽

Loss Rate ◽

Mass Loss Rate ◽

Protective Layer ◽

Average Mass ◽

Microscale Combustion Calorimeter ◽

Combustion Calorimeter

Metal–organic frameworks (MOFs) are emerging as novel flame retardants for polymers, which, typically, can improve their thermal stability and flame retardancy. However, there is a lack of specific studies on the thermal decomposition kinetics of MOF-based polymer composites, although it is known that they are important for the modeling of flaming ignition, burning, and flame spread over them. The thermal decomposition mechanisms of poly (methyl methacrylate) (PMMA) have been well investigated, which makes PMMA an ideal polymer to evaluate how fillers affect its decomposition process and kinetics. Thus, in this study, UiO-66, a common type of MOF, was embedded into PMMA to form a composite. Based on the results from the microscale combustion calorimeter, the values of the apparent activation energy of PMMA/UiO-66 composites were calculated and compared against those of neat PMMA. Furthermore, under cone calorimeter tests, UiO-66, at only 1.5 wt%, can reduce the maximum burning intensity and average mass loss rate of PMMA by 14.3% and 12.4%, respectively. By combining UiO-66 and SiO2 to form a composite, it can contribute to forming a more compact protective layer, which shows a synergistic effect on reducing the maximum burning intensity and average mass loss rate of PMMA by 22.0% and 14.7%, respectively.

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