Non-isothermal Thermogravimetric Analysis Research Articles

Thermal Decomposition and Combustion Analysis of Malaysian Peat Soil Samples Using Coats Redfern Model-free Method

This research investigates the thermal decomposition behaviour of Malaysian peat soil through thermogravimetric analysis at varying heating rates. The study aims to analyse the thermal kinetics of decomposition for distinct peat soil types under inert and oxidative atmospheres while considering the role of available oxygen. The investigation encompasses virgin and agricultural peat, employing a non-isothermal thermogravimetric analysis technique to evaluate thermal decomposition characteristics and compute kinetic parameters using the Coats Redfern model-free approach. The pyrolysis profiles reveal three primary stages: moisture evaporation (30–180°C), organic component decomposition (200–500°C), and mineral decomposition (600–800°C). Virgin peat experiences a 43% mass loss during pyrolysis, while agricultural peat shows a 46% mass loss, emphasising insights into thermal behaviour and consistent decomposition patterns across peat types. Combustion profiles exhibit three main stages: dehydration (30–180°C), oxidative pyrolysis transforming organic matter into volatiles and char (200–300°C), and subsequent char oxidation (300–500°C). The study determines average activation energy trends, measuring 14.87 kJ/mol for virgin peat and 5.37 kJ/mol for agricultural peat under an inert atmosphere, and 28.89 kJ/mol for virgin peat and 36.66 kJ/mol for agricultural peat under an oxidative atmosphere. The research introduces an innovative two-step reaction model elucidating peat thermal decomposition kinetics (excluding dehydration), including a discussion on the impact of oxygen availability on kinetic parameters. These findings essential peat fire smouldering modelling, contributing to peat combustion behaviour for effective strategies to reduce peat fire risks.

Thermal Decomposition Kinetics of Clinochlore at High Temperature and Its Implications

Abstract The dehydration kinetics of clinochlore were performed using a non-isothermal thermogravimetric analysis under a dynamic nitrogen atmosphere at ambient pressure. Clinochlore, with a grain size of 5–10 μm, was analyzed using heating rates of 2, 5, 10, 20, and 40 K/min at temperatures of up to 1260 K. Thermogravimetric data of clinochlore at different heating rates were modeled using the Kissinger method, Flynn-Wall-Ozawa method, and Coats-Redfern method. The dehydration of clinochlore is ascribed to the decomposition of brucite and talc layers. The dehydration temperature of the brucite layer is 730–920 K, which corresponds to a two-dimensional phase boundary model (R2) with an activation energy of 214.94 ± 7.79 kJ/mol and a pre-exponential factor of 12.52 ± 0.62 min−1. The dehydration temperature of the talc-like layer is 960–1140 K, which follows a two-dimensional diffusion model with an apparent activation energy of 419.49 ± 23.62 kJ/mol and a pre-exponential factor of 19.97 ± 1.76 min−1. Combined with the parameters obtained in this study, the fast dehydration of clinochlore can trigger earthquakes in the subduction zone.

The Structure-Function Relationship of Branched Polyethylenimine Impregnated over Mesoporous Carbon Aerogels: An In-Depth Thermogravimetric Insight.

We present a comprehensive thermogravimetric analysis (TGA) of polyethylenimine (PEI)-impregnated resorcinol-formaldehyde (RF) aerogels. While numerous studies focus on PEI-impregnated SBA, RF materials have been less examined, despite their interest and specificities. As most articles on PEI-impregnated porous materials follow typical experimental methods defined for SBA, particularities of RF-PEI materials could remain unheeded. The design of nonisothermal TGA protocols, completed with nitrogen isotherms, based on the systematic filling of the matrix delivers a fundamental understanding of the relationship between the structure and function. This study demonstrates (i) the competition between the matrix and PEI for CO2-physisorption (φ) and CO2-chemisorption (χ), (ii) the hysteresis ([Formula: see text]) of CO2 capture at low temperature attributed to the kinetic (K) hindrance of CO2 diffusion (D) through PEI film/plugs limiting the chemisorption, and (iii) the thermodynamic (θ) equilibrium limiting the capture at high temperature. At variance with SBA-PEI materials, the first layers of PEI in RF are readily available for CO2 capture given that this matrix does not covalently bind PEI as SBA. A facile method allows the discrimination between physi- and chemisorption, exhibiting how the former decreases with PEI coverage. The CO2 capture hysteresis, while seldom introduced or discussed, underlines that the commonly accepted operating temperature of the "maximum capture" is based on an incomplete experiment. Through isotherm adsorption analysis, we correlate the evolution of this maximum to the morphological distribution of PEI. This contribution highlights the specificities of RF-PEI and the advantages of our TGA protocol in understanding the structure/function relationship of this kind of material by avoiding the typical direct applications of SBA-specific protocols. The method is straightforward, does not need large-scale facilities, and is applicable to other materials. Its easiness and rapidness are suited to high-volume studies, befitting for the comprehensive evaluation of interacting factors such as the matrix's nature, pore size, and PEI weight.

Thermo-kinetic Study of Genetically Different Carbon-Source Materials.

A nonisothermal thermogravimetric analysis (TGA) technique was applied to determine the devolatilization kinetic parameters of completely different genesis samples of four groups: coal, biomass, lignite, and petcoke. The physical and chemical characteristics were determined using the proximate and ultimate analysis and the ash composition profile using the X-ray fluorescence method. Heating rates of 10, 15, and 20 °C/min were used in the temperature range of 25-1000 °C during the slow pyrolysis under an inert gas atmosphere. A widely used and proposed first-order Coats-Redfern kinetic model was applied, which showed the highest values of activation energies (Ea) for the petcoke sample from 57.17 to 67.58 kJ/mol at three different heating rates, while the lignite sample represented the lowest Ea values between 12.84 and 16.03 kJ/mol. The thermo-kinetic behavior was explained based on the catalytic effect of the ash composition profile, morphology, and structure of the substances determined using different analytical techniques. For the TGA process, the application of scanning electron microscopy, Fourier-transform infrared spectroscopy, etc., for the physiochemical analysis of the four genetically different carbon-source materials represented the novelty of the present work.

Interphase in polymer-based nanocomposites: Polyoctenamer – Single-walled carbon nanotubes

A detailed and critical analysis of the non-isothermal thermogravimetric analysis of polyoctenamer-single wall carbon nanotube, is presented. The thermogravimetric data were obtained under an inert atmosphere (nitrogen) on polyoctenamer- single wall carbon nanotube nanocomposites loaded by different amounts of nanofiller (up to 10 % wt. single wall carbon nanotube), at various heating rates ranging from 5 to 40 °C/minute.The research focuses on the identification of the polymer-nanofiller interphase, including the detailed dissemination between the interface and interphase. The manuscript aims at the information that can be extracted from the recorded thermograms as well as from the derivatives of the thermograms with respect to the temperature. The detailed analysis of the temperature at which x% of the mass is volatilized, TX%, and of the residual mass fraction at high temperatures (850 °C and 950 °C) provide qualitative support for the presence of interphase.The research demonstrated that the derivatives of the thermograms versus temperature have a better resolution than “standard” thermograms. The derivative of the thermograms provides qualitative information about the formation of an interphase. A model for the degradation of the nanocomposites is proposed by assuming that the dependence of the inflection temperature on the composition of the nanocomposite obeys a Fox-like dependence, where the bulk polymer and the polymer trapped within the interphase are considered as a blend of two miscible polymers.

Kinetics of maize cob and bean straw pyrolysis and combustion

Kinetic studies are important for the design and optimisation of thermochemical processes. This study involved analysis of the pyrolysis and combustion behaviour of the agricultural residues (bean straw and maize cob) by non-isothermal thermogravimetric analysis. Increasing the heating rate from 10 to 40 K min−1 during both combustion and pyrolysis increased the degradation rate of both feedstocks and the gaseous yields of H2O, CO and CO2. The activation energies determined by the Flynn-Wall-Ozawa and Kissinger-Akahira-Sunose methods varied which reveals that the pyrolysis and combustion of these agricultural residues are complex processes involving multiple reactions. The average activation energy of maize cob and bean straw were 214.15 and 252.09 kJ mol−1 for pyrolysis and 202.26 and 165.64 kJ mol−1 for combustion, respectively. The order of reaction ranged between 9.0-10.3 and 6.3–13.3 for both feedstocks in combustion and inert environments, respectively. Modelled data is important to enable the optimisation of reactor design for pyrolysis and combustion for energy generation from agricultural residues.

Assessment of the Influence of Saffron Pollen and Saffron Pollen/Rutin Microcapsules on Thermal and Oxidative Stability of Edible Oil: Thermogravimetric Study

Nowadays, the demand to find natural systems as antioxidants or additives applicable in the food industry without any manipulation or surface engineering is increasing. Accordingly, this study aimed to find a potential natural, eco-friendly, low-cost, and safe antioxidant. Therefore, saffron pollen (SP) and rutin (Ru) were chosen as two potential antioxidants, and their antioxidant activity in sunflower oil (SO) was evaluated by nonisothermal thermogravimetric analysis (TGA/DTA). tert-Butylhydroquinone (TBHQ) was used as an already-proven antioxidant and positive control. The antioxidant activity of rutin-loaded saffron pollen microcapsules was also evaluated. According to the TGA results, SP enhanced the oxidative stability of SO compared to TBHQ. In contrast, its thermal stability was significantly lower than that of TBHQ and Ru. Based on the results of the mass increase in TGA, the antioxidant effect of SP was significantly higher than Ru. These prove that SP can function as a natural antioxidant system in edible oil.

Physicochemical Characterization and Chemical Reactivity of Biochar from Pyrolysis of Dried Distiller’s Grains with Solubles (DDGs)

ABSTRACT Biomass utilization has attracted great attention for decades, and the dried distiller’s grains with solubles (DDGs) is an important source which is the by-product of brewing industries, as fermented from raw biomass such as rice, wheat and sorghum. Currently, there are a few studies on the kinetics and thermodynamics of distiller’s grains biomass. Therefore, the physicochemical characterization, kinetic and thermodynamic analyses of DDGs and DDGs-biochar were studied. The characterization results confirmed that DDGs had high volatile matter (81.6%) and higher heating value (21.3 MJ kg−1). The pyrolysis kinetics of DDGs and DDGs-biochar at four heating rates of 5, 10, 20 and 40 K min−1 were investigated by non-isothermal thermogravimetric analysis. The isoconversional method such as Kissinger-Akahira-Sunose (KAS), analysis showed that the effective activation energy varied with the change in the conversion rates. For DDGs, it was 122–159 kJ mol−1 (α: 0.1–0.2), 160 ± 6.20 kJ mol−1 (α: 0.20–0.75) and 179–194 kJ mol−1 (α > 0.75), corresponded to thermal decomposition of hemicellulose, cellulose and part of lignin, and remaining lignin respectively; as to combustion of DDGs-biochar, it was 152 to 60.1 kJ mol−1 (α: 0.1–0.9) indicated that some of the more complicated structures in DDGs had been carbonized, making as-obtained biochar easier to burn owing to the lower activation energy. The changes in enthalpy, Gibbs free energy and entropy of DDGs and DDGs-biochar were calculated, and the results were helpful to evaluate the conversion efficiency and technical feasibility of DDGs pyrolysis and DDGs-biochar combustion processes.

Kinetics of combustion of lignocellulosic biomass: recent research and critical issues

Predicting biomass combustion at temperatures of practical interest requires kinetic expression robust and reliable over a large temperature range.The present work examines experimental works on combustion kinetics of lignocellulosic biomass published since 2015 and reports the experimental methods used and the kinetic parameters obtained therein. The most common experimental strategy, used in 39 referenced works, was non-isothermal thermogravimetric analysis, yet the kinetic parameters obtained varied by order of magnitude.The large variability of the kinetic parameters found in literature cannot be only explained by the feedstock heterogeneity or the different data analysis methods. One possible and apparently neglected source of error lies in the fact lignocellulosic biomasses are complex materials, constituted by different components, thus thermogravimetric curves are the resultant of multiple and partly overlapping stages of mass loss. Kinetic analysis in this case easily generates errors. Another criticality that the work wants to emphasize is the fact that biomass pyrolyses, burns and even thermally anneals throughout a TGA experiment. These progressive structural changes are a further problem for application of conventional kinetic analysis methods.Altogether, it can be concluded that it is difficult to obtain from conventional TGA analysis reliable kinetic expressions of biomass combustion to be used for boilers modelling. For complex materials like biomass, it is recommended to adopt expert-case sensitive approaches. As an example, the case of walnut shells combustion is presented. For this material, four components with different combustion reactivity have been identified and simplified single rate kinetics are proposed according to the temperature interval of interest.

Mechanistic investigation of pyrolysis kinetics of water hyacinth for biofuel employing isoconversional method

The current study employs non-isothermal thermogravimetric analysis to analyze the thermal degradation behavior of water hyacinth (WH), with the primary goal of determining the kinetic triplet. The pyrolysis of water hyacinth achieved approximately 80% thermal degradation during three phases of breakdown at temperatures ranging from 30 to 900 °C. The activation energy of feedstock breakdown was calculated using four different model-free approaches i.e., Flynn-Wall- Ozawa (FWO), Starink, Friedman, and Kissinger- Akahira-Sunose (KAS), with mean values ranging from 251.33 to 298.48 kJ/mol inside the conversion band of 0.15–0.75. The Master plot results depicted that for conversion (α) ≤ 0.5, the biomass degradation followed a two-dimensional process of diffusion. For α ≥ 0.5, the response, however, is adequately described by growth processes and nucleation. The values of excitation energy estimated using isoconversional techniques were also utilized to determine various thermodynamic parameters. From the thermodynamic study, the mean value of ΔH was 293.66 kJ/mol, suggesting that the generation of activated complex is simpler since the potential energy barrier is lower. A high ΔS value indicates increased reactivity and less time required to synthesize the activated compound. In conclusion, the characterization and kinetic analyses of biomass reveal their potential as pyrolysis feedstock.

Studies on Ablative Performance of Silicone Low-Density Ablative Material

In the present studies, silicon based low-density ablative material has been studied for its ablative performance to protect flight hardware from temperature raises due to aerodynamic forces for a longer duration. The oxyacetylene flame test estimates ablative properties at 100–120 W/m2 heat flux. The time duration for the flame test is taken 200 s. The material shows low mass and linear ablation rate with high ablative effectiveness. The degradation kinetics of silicon ablator is studied by Thermo Gravimetric Analysis (TGA) method. Non-isothermal TGA is performed in the temperature range of 30 °C to 900 °C at various heating rates, viz. 5, 10, 15, and 20 °C/ min. Knowledge of the kinetic parameters of thermal decomposition is used to predict the degradation kinetics of the material at high heating rates, which the ablator faces during aerospace applications. During ablation, the silicone ablative material consists of a virgin zone, reaction zone, and char zone. These are explained by kinetic parameters determined with the help of free software called Kinetic Calculation.

Predicting Pyrolysis of a Wide Variety of Petroleum Coke Using an Independent Parallel Reaction Model and a Backpropagation Neural Network

In this work, the pyrolysis behavior and gaseous products of petroleum coke were investigated by nonisothermal thermogravimetric analysis (TGA) and thermogravimetry-mass spectrometry (TG-MS). Then, the pyrolysis kinetics of six kinds of petroleum coke (Fushun (FS), Fuyu (FY), Wuhan (WH), Zhenhai (ZH), Qilu (QL), and Shijiazhuang (SJZ)) were determined by an independent parallel reaction (IPR) model, and the kinetic parameters (activation energy and preexponential factor) were obtained. In addition, an efficient backpropagation neural network (BPNN) was developed to predict the thermal data of six kinds of petroleum coke. The BPNN-predicted thermal data were used to calculate the kinetic parameters based on the IPR model, and the results were compared with the ones calculated using experimental data. The results showed that the pyrolysis process of six kinds of petroleum coke was divided into three stages, of which stage II (250-900 °C) had the significant mass loss, corresponding to the devolatilization of petroleum coke. MS fragmented ion intensity analysis indicated that the main pyrolysis products were methane CH x (m/z = 13, 14, 15, and 16), aliphatic hydrocarbon C3H5, H2, CO, CO2, and H2O. The thermal data predicted by the IPR, BPNN, and BPNN-IPR (BPNN combined with IPR) models were in good agreement with the experimental data. Most importantly, it was concluded that the BPNN-predicted data can be further applied to calculate the kinetic parameters using the IPR kinetic model.

Intrinsic combustion kinetics of rapid-pyrolysis Zhundong coal char

Driven by the demand for accurate intrinsic kinetics for the prediction of the combustion rate of purely fired Zhundong coal (ZDC) in a slag tapping boiler, the surface activation function (SAF) and intrinsic kinetic parameters of two types of rapid-pyrolysis ZDC chars were revealed via the isothermal and nonisothermal thermogravimetric analysis methods. The isothermal kinetic results show that the activation energy (E), reaction order and SAF of these two chars were the same, at 146 kJ/mol, 0.78 and X0.44 (1 – X)−0.48, respectively. Therefore, the difference in the intrinsic reaction rate between these two chars was caused only by the different pre-exponential factors, which are mainly influenced by the specific surface area and catalytic elements in char ash. Nonisothermal kinetic parameters were obtained via the isothermal model-fitting method (ISOM), thereby using the isothermal SAF to fit the nonisothermal data at different heating rates (βs). The results indicate that the E values of the two chars were 148.95 ± 3.12 kJ/mol and 146.16 ± 1.66 kJ/mol, indicating that β has little influence on E. These measured values are consistent with the isothermal E values, so the ISOM is suitable for the determination of the nonisothermal kinetics of rapid-pyrolysis char combustion.

A novel model to predict the pyrolysis process with preciseness and conciseness: Complementation-Distributed Activation Energy Model (C-DAEM)

In this paper, a novel Complementation-Distributed Activation Energy Model (C-DAEM) has been proposed. The model considered the complementation effect between the frequency factor and the activation energy in the form of a mathematical exponential linearity instead of a constant value of frequency factor in traditional model. To further exhibit the performance of C-DAEM, another DAEM model was chosen to make a contrast, considering the changeable frequency factor with temperature. Two types of coals and biomasses were investigated by non-isothermal thermogravimetric analysis, where the reaction kinetic parameters were achieved by applying three different DAEM models. Thermogravimetric experiments were conducted at five heating rates for each fuel: 5 K/min, 10 K/min, 20 K/min for data fitting and 30 K/min, 40 K/min for model validation. The results indicate that all DAEM models have the ability to describe the pyrolysis process and the C-DAEM model better conforms experimental results compared with traditional DAEM/T-DAEM models. For example, the C-DAEM model has the lowest values of object function (O.F. = 0.0241) and relative root mean square error (RRMSE = 3.53 %) and highest value of coefficient of determination (R2=0.9978) for Shenmu bituminous coal (SMBC), indicating that the C-DAEM model has the characteristic of well-behaved pyrolysis prediction for various fuels under different heating rates. Meanwhile, the clever presumption about the relationship between frequency factor and activation energy, instead of the existing excessive hypotheses, brings the opportunity for C-DAEM model to be combined with CFD simulation, which provides useful insight for the design of industrial pyrolysis reactor.

On the specific heat and mass loss of thermochemical transition

Poly(vinyl alcohol) PVA is a synthetic polymer used in a variety of applications and exhibits unusual thermal behavior. In this work, differential scanning calorimetry (DSC), isothermal and non-isothermal thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), optical microscopy, viscometry and kinetic modeling were used to study the thermal behavior of PVA for providing further insights about the thermochemical transition. It is shown that the value of specific heat of thermochemical transition is comparable to theoretical values derived from chemical bond dissociation energy values. Activation energy's contribution to the specific heat of thermochemical transition seems to be low. Contradictions among the conclusions from various analytical techniques, regarding the glass transition of PVA, are discussed and interpreted. Settlement of these contradictions leads to the conclusion that like PVA's melting point, its glass transition is also a thermochemical transition but with no detectable mass loss.

Thermal dissociation kinetics of solid ammonium carbonate for use in NH3-SCR systems

Selective catalytic reduction (SCR) systems using solid ammonia carriers like carbamates, carbonates, etc., have gained interest in the recent past for NOx abatement from compression ignition engines. Solid ammonia carriers have successfully demonstrated their use in SCR systems. In this experimental study, the thermal dissociation study of ammonium carbonate is made using nonisothermal thermogravimetric analysis. Ammonium carbonate is subjected to three heating rates, emptyset of 2, 4, and 8 K/min. The corresponding highest rates of reaction are obtained at temperatures (T_{p}) of 96, 118, and 128 °C, respectively. At these points, the mass of the samples has been reduced to 1/3rd of the initial mass. From the Arrhenius plots, the average activation energy obtained is 77.39 kJ/mol which is 15% higher than that of ammonium carbamate. An expression for T_{p} as a function of activation energy, emptyset, and order of the reaction is developed using kinetic model. The model can predict the temperatures at which the reaction rates are maximum for a given heating rate.

Research on the co-combustion characteristics and kinetics of agricultural waste hydrochar and anthracite

The study aims to discover the co-combustion reaction mechanism of agricultural waste hydrochar and anthracite and to clarify the main influencing factors of the co-combustion reaction of the mixture. At the same time, it also provides a theoretical basis for revealing the optimal ratio of biomass hydrochar in the mixture and the application of biomass hydrochar in steel plants. Biomass hydrochar and anthracite were systematically investigated by physicochemical property analysis and non-isothermal thermogravimetric analysis. The results show that biomass hydrochar has better combustion performance due to the lower graphitization order and larger specific surface area, while the combustion performance of anthracite is relatively poor. The addition of biomass hydrochar can improve the combustion performance of anthracite. There is an obvious synergy in the co-combustion process due to the differences in the volatile content and graphitization degree of different samples. Two kinetic equations, Kissinger–Akahira–Sunose (KAS) and Flynn–Wall–Ozawa (FWO), are used to perform kinetic fitting on the combustion reaction of the mixture, but the fitting effect of the FWO equation is better than that of the KAS equation. The FWO kinetic fitting results indicate the optimum addition amount of 60% hydrochar with the smallest activation energy (118.95 kJ/mol). The research on the co-combustion of biomass hydrochar and anthracite is vital, contributing to the formation of biomass resource industrial applications.

Hydrolytic, thermal and radiation stability of modified urea-formaldehyde composites: Influence of montmorillonite particle size

Urea-formaldehyde (UF) composites with a formaldehyde/urea (FA/U) ratio = 0.8 and different particle sizes of montmorillonite (MMT), namely UF/KSF and UF/K10 were synthesized. The hydrolytic stability of modified UF composites was determined by measuring the content of the liberated formaldehyde of modified UF composites after acid hydrolysis. The synthesized modified UF composites were irradiated (50 kGy) and the effect of γ–irradiation was evaluated on the basis of these thermal behaviors. The thermal behavior was studied by non-isothermal thermo-gravimetric analysis (TG), differential thermo-gravimetry (DTG), and differential thermal analysis (DTA) supported by data from Fourier transform infrared spectroscopy (FTIR). The minimum percentages of free (0.4%) and liberated (1.2%) formaldehyde were obtained in the UF/KSF composite. The modified UF/KSF composite shows better radiation resistance than the modified UF/K10 composite. The shift of temperature values for the selected mass losses (T5%) to higher temperatures indicates an increase in the thermal stability of the UF/K10 composite after γ–irradiation. γ–irradiation causes a decrease in the absorption intensity of bands in the FTIR spectrum of a modified UF/KSF composite and an increase in the absorption intensity of bands in the FTIR spectrum of a modified UF/K10 composite.

TGA and elemental analysis of type II kerogen from the Bakken supported by HRTEM

In this study, non-isothermal thermogravimetric analysis was conducted on three samples taken from the Bakken Formation at one heating rate (10 °C/min). Based on the TGA thermograms, various intervals of weight loss were identified. The differences in weight loss, peak positions, and shapes of the samples’ thermograms were attributed to the variations in the composition (quantities of silicates and clay minerals), TOC content, and thermal maturity of the kerogen. Moreover, it was observed that the sample with the highest thermal maturity had the highest number of aromatic rings in its structure. XRD analysis demonstrated that the sample with the lowest silicate concentration and the highest clay mineral content lost the most weight during TGA analysis. Furthermore, CHNS elemental analysis indicated that samples with higher thermal maturity levels have higher amounts of C and H elements and lower content of N and S heteroatoms. Ultimately, our results were corroborated by HRTEM (High Resolution Transmission Electron Microscopy) analysis of p-kerogens, thus confirming the abundance of aromatic rings in the samples and delineating the relationship between aromaticity and thermal maturity.

Effect of torrefaction on thermal oxidative degradation kinetics of lignite using multi-distributed activation energy model

Torrefaction treatment is a promising method for lignite upgrading. However, its effect on the combustion characteristics has not been fully evaluated. In this study, the combustion characteristics of lignite and its upgrading samples by torrefaction were studied via non-isothermal thermogravimetric analysis. Results show that increasing the torrefication temperature decreases the volatile content while increasing the fixed-carbon in the fuels. The mole ratios of both H/C and O/C in the samples decreases as the torrefaction temperature increases. Torrefaction treatment significantly improves the combustion performance of lignite with a higher reactivity index S, and the optimum torrefaction temperature was determined to be 200 °C. The upgrading lignite by torrefaction at 200 °C has the lowest temperatures of Tf and Tp as well as the maximum corresponding DTG value. Furthermore, the results of three-parallel-DAEM model analysis results show that the activation energies corresponding to the three peaks are 176.1 kJ/mol, 186.5 kJ/mol and 221.7 kJ/mol, respectively, and that increasing torrefaction temperature had no significant effects on activation energies. With the torrefaction temperature increasing, the first standard deviation decreased while the third standard deviation increased.