Master Plot Method Research Articles

Effect ofCaSt2/ESOthermal stabilizers on the preparation, thermal stability, and thermal stability mechanism of self‐made vinylidene chloride‐methyl acrylate copolymer resin film

AbstractThe effects of heat stabilizer systems on the thermal stability and processability of self‐made vinylidene chloride‐methyl acrylate copolymer (PVDC‐MA) film were investigated via accelerated aging test, Congo red test, FTIR, DMA, and TG‐FTIR. These results displayed that CaSt2/ESO performed excellently in synergistic inhibition of PVDC‐MA thermal degradation. Especially, when the mass ratio of CaSt2/ESO was 1.5:1.5, the static thermal stability time of PVDC‐MA was increased from 14.5 to 46.5 min. The kinetic calculation results also verified this point. Compared with pure PVDC‐MA, the average apparent activation energy (Ēa) of thermal degradation reaction of PVDC‐MA stabilized by CaSt2/ESO enhanced from 144.1 to 169.7 kJ mol−1(α0 ≤ 0.1), indicating that the thermal stability of PVDC‐MA in the initial thermal degradation stage was dramatically improved by CaSt2/ESO. Moreover, the mechanism of the effect of CaSt2/ESO on PVDC‐MA in the initial thermal degradation stage was further explored by the generalized master plot methods. The kinetic analysis result suggested that under the synergistic effect of CaSt2/ESO, the mechanism model followed by the degradation of PVDC‐MA changed essentially (the three‐dimensional diffusion thermal degradation mechanism transformed into two‐dimensional diffusion).

Non-isothermal solid-state synthesis kinetics of the tetragonal barium titanate

The solid-state synthesis kinetics of the barium titanate is investigated through thermogravimetry analysis (TGA), and derivative thermogravimetry (DTG). The XRD results confirmed the formation of pure tetragonal BaTiO3 after thermal analysis. The thermodynamic parameters (ΔH,ΔS,ΔG) are calculated for all possible reactions involved during the formation of BaTiO3. The thermodynamic analysis predicted the formation of intermediate compounds (BaO, Ba2TiO4). The thermal kinetic analysis is also performed by using the deconvolution kinetic method. The thermal profile is convoluted in three peaks and the kinetic triplets are calculated. The activation energy is calculated by using the iso-conversional KAS kinetic model based on the Straink approximation. The order of the average activation energy is Peak III (225.81 ​kJ/mol) ​> ​Peak II (223.88 ​kJ/mol) ​> ​Peak I (197.67 ​kJ/mol). The reaction mechanism and pre-exponential are identified by the integral master plot method. The F1, R2 and A4 reaction mechanisms dominated the reaction occurring in peak I, peak II and peak III, respectively.

Insights into the thermal decomposition of organometallic compound ferrocene carboxaldehyde as precursor for hematite nanoparticles synthesis

Abstract The paper deals with the thermal decomposition of organometallic compound ferrocene carboxaldehyde [(C5H4CHO)Fe(C5H5)] in oxidative atmosphere, which leads to pure hematite nanoparticles, studied with non-isothermal thermogravimetry (TG) protocol. Deconvolution method with Fraser-Suzuki fit function is adopted to resolve the complex multistep TG profiles into six different reaction steps. Step-wise reaction kinetic parameters (activation energy, reaction mechanism function, reaction rate) are estimated based on the mathematical analysis of the multi-heating rate TG data primarily following model-free (integral isoconversional) approach and using master-plot method. The estimated kinetic parameters are utilised to reconstruct the conversion plots which successfully resemble the experimentally observed ones. A plausible reaction process leading to hematite on thermal decomposition of ferrocene carboxaldehyde as the end product is discussed. A comparative discussion on the thermal decomposition of two ferrocene derivatives have been made. The novelty of the present work lies in successful deconvolution of complex TG profiles and hence obtaining the step-wise reaction kinetic parameters demonstrating different reaction mechanisms involved in the thermal synthesis of hematite nanoparticles starting from ferrocene carboxaldehyde which have no prior reporting. Further, a satisfactory agreement between the reconstructed and experimental decomposition profiles establishes the correctness of the applied modelling approach as well as the methodology adopted.

Investigating transformation kinetics of yttrium hydroxide to yttrium oxide

The transformation kinetics involved during the formation of yttrium oxide through thermal dehydration of yttrium hydroxide was studied through differential thermal analysis (DTA) at multiple heating rates (1, 5, 7, 10 °C/min) in air. The yttrium hydroxide dehydrates in two steps to form yttrium oxide. The intermediate compound, i.e., YOOH was formed at 350 °C. The phase formation was confirmed through XRD and Le-Bail profile matching. FESEM confirms the dehydration of yttrium hydroxide and a rod-shaped microstructure was observed. An increase in temperature resulted in shrinkage of the rods. The kinetic triplets (activation energy, pre-exponential factor and reaction mechanism) were estimated for both the steps. The Straink method was used to evaluate activation energy, whereas the reaction mechanism was identified through the integral master plot method. The activation energy was 219.6 kJ/mol and 431.3 kJ/mol for step I and II of dehydration, respectively. Step I was dominated by the A2 reaction mechanism, while the F1 reaction mechanism was found in step II of yttrium hydroxide dehydration.

Effects of CaO-Fe2O3-Fe3(PO4)2 in sewage sludge on combustion characteristics and kinetics of coal slime

The co-combustion of sewage sludge (SS) and coal slime (CS) is a promising approach to realize the harmless disposal of these two solid wastes. Aiming at the effects of the minerals in SS on CS combustion during the co-combustion, the combustion characteristics and kinetics of CS under the action of CaO, Fe2O3, and Fe3(PO4)2 were investigated by a thermogravimetric analyzer. The effects of the single and the composite minerals on CS combustion were quantified, and the synergistic or inhibitory effects between the minerals were also analyzed. Furthermore, Flynn-Wall-Ozawa (FWO) method and the master plots method were used to calculate the combustion kinetics. The results revealed that the catalysis of the minerals in SS was an important factor for the interaction between SS and CS during the co-combustion. For the single minerals, Fe2O3 exhibited the best catalytic effect, which reduced the ignition temperature (Ti) and burnout temperature (Tb) by 8.2 °C and 42.2 °C, respectively, and increased the comprehensive combustion characteristic index (S) by 10.7%. For the composite minerals, Fe2O3 and CaO synergistically catalyzed CS combustion through a cascade chain catalytic mechanism, resulting in a 15.9% increase in S compared with CS combustion alone. However, the interaction between Fe2O3 and Fe3(PO4)2 at high temperatures produced dense products that inhibit the burnout process. The kinetic results showed that the minerals in SS led to a decrease in the apparent activation energy of CS during the combustion stage of the fixed carbon, and the order of decreasing degree was Fe2O3 + CaO > Fe2O3 > Fe2O3 + CaO + Fe3(PO4)2. In addition, the combustion of CS was a multi-step kinetic process, and the mechanism function changed from f(α)= (1-α)4 to f(α)= (1-α) as the combustion progressed. The composite mineral Fe2O3 + CaO participated in the combustion reaction of fixed carbon in CS, changing the reaction mechanism from F1 to F1.3.

Investigation on prospective bioenergy from pyrolysis of butia seed waste using TGA-FTIR: Assessment of kinetic triplet, thermodynamic parameters and evolved volatiles

The pyrolysis of butia seed waste (BSW) was investigated under a thermogravimetric scale at multiples heating rates (5–40 °C min−1) in a nitrogen atmosphere. First, the pyrolysis behavior of BSW was deconvoluted into four independent reactions using the Asym2Sig fitting function. The kinetic triplets (activation energies, pre-exponential factors, and reaction models) were acquired using four isoconversional methods, the compensation effect method and the master plot method. The kinetic parameters estimated were in the range of 111.5–190.9 kJ mol−1 for the average activation energy and 1.55 × 1010–2.89 × 1014 min−1 for the pre-exponential factor. According to the master plot method, the pyrolysis of BSW is described by the summative effect of geometrical contraction and n-order reaction mechanisms. A multi-component kinetic approach was suitable for capturing the complexity involved in the pyrolysis of BSW, with a coefficient of determination (R2) > 0.95 and quality of fit (QOF) > 93%. Pyrolytic conversion of BSW into biofuels is characterized by an endothermic nature (ΔH > 0) and low reactivity (ΔS < 0). The volatile products evolved from the pyrolytic decomposition of BSW were characterized using the integrated TGA-FTIR system, which confirmed the presence of high-energy compounds (aromatics) and useful chemicals (aldehyde, ketone, esters, ether, and alcohols).

Pyrolysis of anaerobic digested residues in the presence of catalyst-sorbent bifunctional material: Pyrolysis characteristics, kinetics and evolved gas analysis

We investigated the potential application of anaerobically digested residues for generating bioenergy in the presence of alkali bifunctional material, sodium zirconate (Na2ZrO3, NZ) using a thermogravimetric analyzer connected to a mass spectrometer. Isoconversional kinetic models, compensation effect and master-plots method were used on data obtained under multiple heating rates (10, 15 and 20 °C min−1) to calculate the activation energy (Eα) and pre-exponential value (A) and reaction mechanism. The average Eα for blend samples C-DSW (NZ mixed with digested municipal solid waste (DSW)), and C-DSM (NZ mixed with digested swine manure (DSM)) were 172.24 and 171.63 kJ mol−1, which were much lower when compared to plain samples, DSW (202.51 kJ mol−1) and DSM (215.22 kJ mol−1). The total gas yields increased by 19.5 and 17.1% for NZ blended samples C-DSW and C-DSM, respectively. In addition, the hydrogen yields also increased by 79 and 44% for C-DSW and C-DSM, respectively.

Evaluating the bioenergy potential of cupuassu shell through pyrolysis kinetics, thermodynamic parameters of activation, and evolved gas analysis with TG/FTIR technique

This research aimed to investigate the physicochemical properties and the pyrolysis performance of cupuassu shell (Theobroma grandiflorum) under a thermogravimetric scale. The pyrolysis experiments were carried out using a pure nitrogen atmosphere and at five heating rates (5, 10, 20, 30, and 40 K min−1). The pyrolysis kinetic triplet was calculated from the DTG thermograms using the isoconversional methods of Friedman, Flynn–Wall–Ozawa, Kissinger–Akahira–Sunose, and Starink combined with the compensation effect and master plots methods. TGA analyses revealed that cupuassu shell pyrolysis follows a devolatilization process of two steps: (1) represented by the two-dimensional diffusion-reaction model (D2), with average activation energies within 102.9–107.5 kJ mol−1, and (2) represented by the fourth-order reaction model (F4) with average activation energies within 176.7–243.0 kJ mol−1. Still, the pre-exponential factor value for the first kinetic stage (1.64×108 min−1) was lower than that of the second kinetic stage (3.19×1010 min−1). As verified, the kinetic triplets efficiently derived the global kinetic expression of cupuassu shell pyrolysis, reproducing reliable data on conversion rates. The evaluation of thermodynamic parameters of activation showed that cupuassu shell is viable biomass for pyrolysis applications, with values of ΔH≠ > 0, ΔG≠ > 0, and ΔS≠ < 0. The TGA-FTIR analysis showed that the evolved pyrolysis products were dominated by alcohols, aldehydes, ketones, organic acids, and aromatic/aliphatic hydrocarbons, supporting the utility of cupuassu shell as a potential source for bio-based chemicals production. In summary, the insights of this study validate the cupuassu shell as a prospective feedstock for producing bioenergy and bio-based chemicals, also bringing useful information for engineering purposes in the design or simulation of large-scale pyrolysis reactors.

Pyrolysis kinetics of [4-(hydroxymethyl)phenoxymethyl]polystyrene (Wang) resin using master-plot method and distributed reactivity model

Pyrolysis kinetics of [4-(hydroxymethyl)phenoxymethyl]polystyrene (Wang) resin using master-plot method and distributed reactivity model

Degradation mechanism and oxidation kinetics of C60 fullerene

Despite a great deal of research on the basic properties of C60 to the present, no detailed and comprehensive reports are available concerning its degradation mechanism and oxidation kinetics. However, a deeper understanding of the oxidation mechanism of the most common fullerene broadens the horizons of potential applications, especially at high temperatures. Therefore, this study attempted to investigate the fullerene oxidation process using kinetic analysis under non-isothermal conditions. Initially, the powder was structurally and morphologically characterized accurately via XRD, Raman spectroscopy, FESEM, and TEM analyses. This was followed by simultaneous thermal analysis (STA) (i.e., TG and DSC) at four different heating rates (2.5, 5, 10, and 15 °C min−1) in airflow, and kinetic analysis was subsequently conducted to evaluate the thermal oxidation of C60. The activation energy as evaluated by model-free methods turned out to be almost invariant within the specified range of reaction fraction (α). Model-fitting methods were also employed to identify the oxidation mechanism involved, from which emerged two models (i.e., R3 (g(α) = 1-(1-α)1/3) and F1 (g(α) = −ln(1-α))) as possible reaction mechanisms. However, further investigation using the Z(α) master plot method revealed that the kinetic model R3, a phase-boundary process, is the controlling mechanism of C60 oxidation with E ≈ 96 kJ mol−1 and lnA ≈ 9.1 min−1. Further examinations were conducted in the neutral atmosphere, and the partial oxidation process based on TEM and FESEM images revealed that oxygen and heat applied during the process play a central role in the deagglomeration of C60 particles and the consequent oxidation. In fact, considering the spherical morphology and the agglomerates present in the C60 powder, the contracting sphere kinetic model (R3) was found to capture the oxidation process due to attacks by the oxygen molecules at the interface of C60 powder agglomerates.

Pyrolysis of sulfuric acid-treated chrome-tanned leather wastes: Kinetics, mechanism and evolved gas analysis

Management and safe disposal of chrome-tanned leather wastes generated in leather industry are of great importance due to their potential health risks and environmental hazards. Herein, an integrated strategy was proposed for disposing of chrome-tanned leather scrap (CTLS). This method involves the separation of chromium salts from CTLS with sulfuric acid for recycling purpose, followed by pyrolysis of the acid-treated CTLS in an inert atmosphere. SEM/EDX analysis was employed to characterize the changes in composition and morphology of CTLS after acid treatment. CO2 and H2O are main pyrolysis gases of CTLS, while the acid treatment increases the relative content of aliphatic hydrocarbons and NH3 in evolved gases. The pyrolysis characteristics and kinetics of the acid-treated CTLS were investigated by thermogravimetric analysis (TGA) at three different heating rates. After 3 and 6 days of acid treatment, the average activation energy of CTLS (450.9 kJ/mol) obtained from the Flynn-Wall-Ozawa method decreased to 369.6 and 351.0 kJ/mol, respectively. It is assumed that the CTLS consists of two pseudocomponents: low-crosslinked collagen (LCol) and highly-crosslinked collagen (HCol). Using the generalized master plots method, random nucleation and nuclei growth model (An model) was found to be the most probable kinetic model for the pyrolysis process of LCol and HCol. The kinetic exponent for pseudocomponent pyrolysis varied between 3.00 and 3.90, and the pre-exponential factor ranged from 5.83 × 1012 to 2.93 × 1013 min−1. The results of the present study provide an alternative route and useful information for recycling and disposing of chrome-containing leather wastes.

Influence of water on thermo-oxidative behavior and kinetic triplets of shale oil during combustion

The oxidation reactions between oxygen and shale oil directly affect the feasibility and performance of air injection. In this work, the influence of water on thermo-oxidative behavior of shale oil was studied using high-pressure differential scanning calorimetry (HP-DSC). Subsequently, the kinetic triplets for shale oil oxidation in the absence and presence of water were determined using Friedman and Ozawa-Flynn-Wall (OFW) models as well as one advanced integral master plots method. The HP-DSC results showed that at 5 MPa, the shale oil was vulnerable to obviously higher heat release at the low-temperature oxidation (LTO) region compared to the high-temperature oxidation (HTO) region, resulting in shortening the oxidative induction time and achieving in-situ upgrading of shale oil. Water delayed the initial heat release due to the fact that heat release yielded by LTO compensated the heat adsorption yielded by evaporation of water and light hydrocarbons. Additionally, the heat release was reduced with the elevated water saturation as a result of the reduction in exothermic rates and intensified evaporation of water and light hydrocarbons. The higher energy was needed to trigger off the LTO reactions while increasing water saturation from 10% to 20%. Therefore, it was believed that the presence of water extended the oxidative induction time, thereby hindering the smooth and rapid transition from the LTO to HTO stages. Water changed the reactivity of each oxidation stage for shale oil, resulting in higher energy required for the initial LTO reactions and lower energy required for the subsequent oxidation reactions. The water saturation range of 10% to 15% could accelerate the occurrence of high-temperature combustion most effectively, demonstrated by values of activation energy for the conversion greater than 0.6. The appropriate oxidation reaction models for shale oil alone and water saturations of 10%, 15%, and 20% were determined to be D2, F1, F3, and R3, respectively. The determination of kinetic triplets assisted in building the reaction schemes for modelling the air injection process of shale oil reservoirs.

Co-pyrolysis of lignocellulosic biomass and plastics: A comprehensive study on pyrolysis kinetics and characteristics

Co-pyrolysis of biomass with plastics is an interesting research trend in improving both the yield and quality of oil products toward taking advantage of flexible material resources and sustainable fuel development. This study investigated the kinetic behaviors using thermogravimetric analysis and pyrolysis characterization for the co-pyrolysis of biomass (bamboo and oak wood) with plastics (polypropylene [PP] and polystyrene [PS]) in a fixed-bed reactor. The kinetic triplet for feedstocks was determined using the isoconversional method, compensation effect, and master plot method. The addition of 20 wt% plastics into biomass decreased the activation energy, with the most distinct positive synergistic effect for the bamboo/PS blend. In addition, the effect of co-pyrolysis temperature and biomass/plastic ratio on pyrolysis characteristics was investigated. Through biomass pyrolysis and biomass/plastic co-pyrolysis, the positive changes in distributions and physical-chemical properties of the products (i.e., char, oil, and gas) were observed using various analytical methods. Especially in the case of biomass/PS blends, the synergistic effect of co-pyrolysis was shown due to the difference in the actual and theoretical yields of the products. The liquid yields of the co-pyrolysis were 50.95, 50.17, 55.15, and 56.16 wt% for bamboo/PP, bamboo/PS, oak wood/PP, and oak wood/PS, respectively. The highest HHV of 28.22 MJ/kg was obtained for oil derived from the co-pyrolysis of bamboo/PS. Furthermore, co-pyrolysis chars have high HHVs in the range of 30.73–32.41 MJ/kg, suggesting that they can be used as solid fuels.

Investigation on co-combustion of coal gasification fine ash and raw coal blends: Thermal conversion, gas pollutant emission and kinetic analyses

Coal gasification fine ash (CGFA) is produced in huge quantities, has high carbon content and fine particle characteristics, and is environmentally polluting and energy wasting. Co-combustion of CGFA and raw coal (RC) is a way to recover CGFA energy. The aim of this work is to investigate the effects of thermal conversion, synergistic behaviour, kinetics, thermodynamics and gas release behaviour (especially of polluting gases) during the co-combustion of CGFA in air atmosphere. The results showed that the addition of RC to CGFA reduced the activation energy of the mixture and improved the combustion performance and combustion stability of CGFA, and the combustion performance of the mixture with 30% CGFA was comparable to that of Yangquan anthracite. A significant synergistic interaction between CGFA and RC occurred during the co-combustion process, and this interaction inhibited the formation of gaseous pollutants, especially reducing the formation of gaseous emissions (NH3, NO, NO2 and SO2). Average activation energy was described using four iso-conversion and integral master plots methods. The co-combustion for CGFA and RC were best described by the reaction order and random nucleation mechanisms. Our results contribute to developing the new strategies of energy with the CGFA combustion.

Thermal stability and non‐isothermal kinetics of poly(ethyl cyanoacrylate) nanofibers

AbstractA thermogravimetric study of poly(ethyl cyanoacrylate) nanofibers was carried out at five heating rates with a linear increase in the temperature in a nitrogen atmosphere. The data provided by the thermogravimetric study were used to evaluate the kinetics of the degradation process using three isoconversional methods. Considering that the kinetic parameters of the process depend on the reaction mechanism, various approaches were applied in order to determine the most probable mechanism function. In this respect, the mechanism of thermal degradation of poly(ethyl cyanoacrylate) is a phase boundary reaction with cylindrical symmetry (F0.5 function) as demonstrated by the z(α) master plots method, iso‐temperature method and isoconversional method. On their basis, the values of the kinetic triplet (Ea, A and the shape of the most appropriate f(α) function) of the process were obtained, and subsequently the thermodynamic functions of the activated complex formation were calculated. The thermal stability of the polymer was predicted according to the integral procedure decomposition temperature. © 2022 Society of Chemical Industry.

Studies of physicochemical properties, kinetic behaviour, and thermal degradation profile of waste bio-crude derived from slow pyrolysis in a nitrogen atmosphere

The present study is focused on the physicochemical characterization and thermal degradation studies of waste bio-crude. The study of bio-crude kinetics was executed in a thermogravimetric analyzer (TGA), using Kissinger-Akahira-Sunose (KAS), Ozawa-Flynn-Wall (OFW), Friedman (FM), Starink (ST), Cots-Redfern model (CR), and master plot method. Detailed characterization of the bio-crude was carried out by using elemental analysis, examining ash content, viscosity, cold properties, heating value, moisture content, FTIR, GC–MS, and acidity. The results of the physicochemical investigations of bio-crude revealed significant carbon content (67.70%), higher heating value (26.12 MJ kg−1), lower moisture (0.09%), and ash content (1.57%). The kinetic results underscore multi-step reactions and apparent activation energy that increases with progressive conversion. FTIR study established the occurrence of water, alkenes, acids, aromatics, and oxygenated products, whereas the GC–MS study confirmed higher hydrocarbon (14.20%) and lower oxygenated product in BO-1 compared to BO-2.

Bioenergy potential analysis of Brazil nut biomass residues through pyrolysis: Gas emission, kinetics, and thermodynamic parameters

The kinetics of the pyrolysis of Brazil nut residues (Bertholletia excelsa), in this case, shells (BNS) and husks (BNH), were investigated via a thermogravimetric analysis in an inert atmosphere. The Flynn–Wall–Ozawa, Kissinger-Akahira-Sunose, Starink and Vyazovkin isoconversional models were used to estimate kinetic and thermodynamic parameters. The mean activation energy values ranged from 135.59 to 138.51 kJ/mol for the shells and from 151.94 to 153.92 kJ/mol for the husks in the active pyrolysis region. High values of the pre-exponential factor (>108 s−1) indicated the presence of complex reactions for both samples, which was confirmed in the analysis of the reaction mechanism using the master-plot method, through the multiple types of behavior during the variation of the conversion levels. Thermodynamic parameters, such as the enthalpy change, Gibbs free energy change and entropy change, characterized a nonspontaneous endothermic process, with little energy required. TG-MS analyses revealed less harmful gas emission behavior for the environment compared to fossil fuels. The results of the study, with an emphasis on its satisfactory higher heating value (13.8 and 14.6 MJ/kg), showed that Brazil nut residues, an Amazon Forest waste, have great potential in pyrolysis applications for the generation of renewable energy, which can contribute to forest preservation through the development of the circular bioeconomy.

Effect of torrefaction temperature on spent coffee grounds thermal behaviour and kinetics

The paper aimed to investigate the influence of the torrefaction temperature (210, 235, 260 °C) on the kinetic and thermodynamic parameters, as well as the reaction mechanism during combustion of spent coffee grounds (SCGs). Non-isothermal thermogravimetric experiments were carried out at four heating rates, namely, 5, 7, 10, and 15 °C/min. Thermogravimetric (TG) and differential thermogravimetric (DTG) results showed torrefaction temperature firstly increases and then decreases the combustion reactivity, reaching the best value for the sample SCGs-235. Starink, Kissinger-Akahira-Sunose (KAS) and Ozawa-Flynn-Wall (OFW) iso-conversional models, master plots method and the compensation effect method were used to calculate the combustion kinetic triplet of the samples. The activation energy of the samples decreased with torrefaction temperature increasing, from 199.76 kJ/mol to 168.91 kJ/mol (with the Starink model). All the combustions were best explained by a reaction order model whose order decreased with the elevated torrefaction temperature and the heating rate of the combustion process. Using kinetic parameters obtained from the Starink method, thermodynamic parameters (enthalpy, Gibbs free energy, and entropy) were also determined, showing that SCGs seemed to be more suitable for the torrefaction at 235–260 °C. The study findings can provide practical information for modelling and designing combustion reactors for clean biofuel production from SCGs.

Combustion and pyrolysis kinetics of Australian lignite coal and validation by artificial neural networks

Lignite (AL), with a calorific value of 5.9 MJ/kg is the most abundant low-rank coal used widely in power generation. AL's combustion and pyrolysis characteristics were investigated to provide scientific findings using thermogravimetric analysis under non-isothermal conditions. Methods utilized in the kinetic investigation included Vyazovkin, Flynn-Ozawa-Wall (FOW), Kissinger-Akahira-Sunose (KAS), Freidman, Doyle, Arrhenius, Freeman-Caroll, and Sharp-Wentworth. Multiple heating rate methods delivered the activation energy (Ea) as 194–211 kJ/mol (combustion) and 450–470 kJ/mol (pyrolysis). Combustion process followed two dimensional diffusional reaction (2D), volume contracting (R3) solid-state reaction mechanism models and pyrolysis followed volume contracting (R3) as determined by CR (Coats-Redfern), KC (Kennedy-Clark) methods. Master Plot method validated the mechanisms and concluded that it is of deaccelerating type. Improper combustion at a higher heating rate (50 °C/min) was indicated with an increase in burnout Tb, ignition Ti, peak Tp temperatures. Combustion indices (CHCI, IG, IB) reported highest values of 4.99 E−10 mg2 min−2 OC−3, 4.19E-05 mg2 min−3, 2.65 mg2 min−4 at lowest heating rates. AL's analytical thermal degradation behavior results were validated using artificial neural networks with best-fit models NNA 7,8. The research study offers a useful guide for spontaneous AL combustion and pyrolysis prediction on site.

Potential of macauba endocarp (Acrocomia aculeate) for bioenergy production: Multi-component kinetic study and estimation of thermodynamic parameters of activation

This work provides the first insights on the bioenergy potential of macauba endocarp (Acrocomia aculeate) based on the pyrolysis kinetics and thermodynamic parameters of activation. The kinetic triplet was obtained from non-isothermal thermogravimetric data by using four isoconversional methods, kinetic compensation effect, and master-plots method. The pyrolysis behavior of macauba endocarp was modeled with three independent parallel reactions, describing the devolatilization of pseudo-hemicellulose, pseudo-cellulose and pseudo-lignin, with average activation energies of 90.2 − 99.5, 113.6 − 123.9 and 153.0 − 167.3 kJ mol−1, respectively. Based on the pre-exponential factors, the devolatilization of both pseudo-hemicellulose and pseudo-cellulose occurred through surface reactions (≤ 109 min−1), while pseudo-lignin devolatilized through a simpler chemistry reaction (> 109 min−1). The master-plots method results showed that the devolatilization of pseudo-hemicellulose and pseudo-cellulose followed R-type models, while the devolatilization of pseudo-lignin followed an F-type model. The thermodynamic analysis indicated that macauba endocarp is a viable feedstock for bioenergy production. The summative kinetic expression proposed from the kinetic results was able to reproduce and predict with excellence the experimental behavior of macauba endocarp pyrolysis (R2 > 0.99 and Fit > 95.50%). This work's insights provide a new reference for future applications of macauba endocarp as an attractive and environmentally friendly alternative for bioenergy production.