Flynn-Wall-Ozawa Research Articles

Pyrolysis behavior of sewage sludge coexisted with microplastics: Kinetics, mechanism, and product characteristics

Microplastics can accumulate in the excess sludge from wastewater treatment plants through domestic wastewater. This study investigated the co-pyrolysis behavior of sewage sludge coexisting with two types of microplastics (polyethylene (PE) and polylactic acid (PLA)) and found a superior comprehensive pyrolysis performance. By calculating the difference between theoretical and experimental weight loss during the pyrolysis process, it was found that the incorporation of microplastics PE and PLA created a synergistic effect at 270°C–450 °C, which was confirmed through the Malek method analysis from a pyrolysis mechanism perspective that it could increase the random nuclei on each particle, that is, enhance the heterogeneous diffusion of volatiles. The average activation energy was reduced by 84.99 kJ/mol, as determined using three isoconversional methods: Flynn-Wall-Ozawa (FWO), Kissinger-Akahira-Sunose (KAS), and Starink. Regarding the products, the aforementioned synergistic effect led to a reduction in char retention and larger specific surface area of the biochar, while the quantities of gaseous products and bio-oil escalated. Through a thermogravimetric analyzer and Fourier transform infrared spectroscopy (TG-FTIR), an increase in aromatic hydrocarbons, alkanes, aldehydes, ethers, and esters in the gaseous products were detected. Pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) revealed an increase in hydrocarbons, esters, and alcohols in the bio-oil, and acids and aldehydes decreased, overall enhancing the quality of the bio-oil. This study elucidated that pyrolysis completely transformed microplastics in sludge, thus eliminating environmental risks and provided a theoretical reference for understanding the pyrolysis behavior of sludge containing microplastics.

Effect of fullerene (C70) on the structural, morphological optical and thermal properties of poly(butyl methacrylate) (PBMA)

Poly(butyl methacrylate) (PBMA)/Fullerene (C70) nanocomposites were successfully prepared by solvent removal method and characterized by different techniques. Structural characterization showed an interaction between PBMA and C70 nanofiller. Morphological features showed that C70 was homogeneously distributed in the PBMA matrix. Optical analysis confirmed the formation of nanocomposites with wavelength shift in PBMA/C70 nanocomposites compared to pure PBMA. Photoluminescence spectra showed that the emission bands of PBMA/C70 nanocomposites shifted from blue to red and the presence of new emission spectra in the red region. The data obtained from thermal analysis showed that the Tg of the nanocomposites increased by about 10 °C compared to pure PBMA and the maximum decomposition temperatures improved by about 65–70 °C, confirming the increased thermal stability. The data obtained from thermogravimetric analyses performed at different heating rates were analyzed by Kissinger-Akahira-Sunose (KAS) and Flynn-Wall-Ozawa (FWO) equations to calculate the activation energy values. According to the regression coefficient values, the experimental results were in good agreement with the FWO method (R2 PBMA=0.937 and R2 PBMA/C70 (5 wt%)=0.953). The activation energy of PBMA and fullerene doped nanocomposite were calculated as 48 kJ/mol and 104 kJ/mol, respectively and the results showed that the Ea value of nanocomposite was higher than PBMA.

Machine learning based prediction and iso-conversional assessment of oxidatively torrefied spent coffee grounds pyrolysis

This research focused on developing a predictive model for mass loss during the pyrolysis of oxidatively torrefied spent coffee grounds (SCG) using machine learning techniques. Four algorithms were employed: artificial neural networks (ANN), k-nearest neighbors (k-NN), random forest (RF), and decision tree (DT), with the RF model demonstrating superior performance (R2 > 0.9981, RMSE <1.346) for both training and testing sets. The pyrolysis behavior, kinetics, and thermodynamics of SCG were also investigated using thermogravimetric analysis (TGA) under an inert atmosphere at different heating rates. Higher heating rates in TGA cause Tpeak values to shift to higher temperatures with increased DTGpeak values, while also resulting in lower Tonset and higher Toffset. Kinetic analysis, using the Flynn-Wall-Ozawa (FWO) method, was identified as the most suitable approach for determining activation energy (Ea), with values ranging from 192.66 to 288.13 kJ mol−1, indicating differences in energy requirements for pyrolysis across samples. Thermodynamic analysis further revealed that both raw SCG and oxidatively torrefied SCG pyrolysis were endothermic reactions. These findings contribute valuable insights into the optimization of biomass conversion technologies, highlighting the potential of machine learning in improving predictive accuracy and efficiency in thermal behavior modeling. This research advances sustainable bioenergy production by promoting the use of SCG, an abundant waste material, as a renewable feedstock in pyrolysis-based processes.

Kinetic analysis of coal oxidative pyrolysis before and after immersion effect

The oxidative pyrolysis kinetics of coal before and after immersion effect was studied by thermogravimetric experiments. Non-isothermal thermogravimetric analysis data were analyzed at four heating rates of 5, 10, 20 and 30 K/min. Furthermore, temperature-programmed experiments and Fourier-transform infrared (FTIR) spectroscopy were employed to understand the oxidation activity and chemical structure of raw coal and soaked coal. After coal immersion effect, the increase in the content of active functional groups, the increase in the concentration of gaseous products, and the decrease in crossing point temperature during oxidation process all indicate that soaked coal is easier to oxidize and spontaneously combust. Lastly, four model-free methods such as Flynn-Wall-Ozawa (FWO), Kissinger-Akahira-Sunose (KAS), Friedman and Kissinger methods are employed to calculate the activation energy (Eα). Kinetic analysis reveals that Eα value obtained by the former three methods significantly depends on the conversion of coal oxidative pyrolysis process, and the average Eα value of soaked coal obtained by four methods is lower than that of raw coal. For the kinetic analysis of coal oxygen adsorption and combustion stages, it is more reliable to adopt the FWO and KAS methods in turn. This research helps to better understand the mechanism of enhanced oxidation activity of soaked coal and optimizes the calculation method of kinetic parameters in different oxidation stages of coal.

Experimental Study on the Thermal Behavior Characteristics of the Oxidative Spontaneous Combustion Process of Fischer–Tropsch Wax Residue

Coal-to-liquid technology is a key technology to ensuring national energy security, with the Fischer–Tropsch synthesis process at its core. However, in actual production, Fischer–Tropsch wax residue exhibits the characteristics of spontaneous combustion due to heat accumulation, posing a fire hazard when exposed to air for extended periods. This significantly threatens the safe production operations of coal-to-liquid chemical enterprises. This study primarily focuses on the experimental investigation of the oxidative spontaneous combustion process of three typical types of wax residues produced during Fischer–Tropsch synthesis. Differential Scanning Calorimetry (DSC) was used to test the thermal flow curves of the three wax residue samples. Kinetic analysis was performed using the Kissinger–Akahira–Sunose (KAS) and Flynn–Wall–Ozawa (FWO) methods to calculate their apparent activation energy. This study analyzed the thermal behavior characteristics, exothermic properties, and kinetic parameters of three typical wax residue samples, exploring the ease of reaction between wax residues and oxygen and their tendency for spontaneous combustion. The results indicate that Wax Residue 1 is rich in low-carbon chain alkanes and olefins, Wax Residue 2 contains relatively fewer low-carbon chain alkanes and olefins, while Wax Residue 3 primarily consists of high-carbon chain alkanes and olefins. This leads to different thermal behavior characteristics among the three typical wax residue samples, with Wax Residue 1 having the lowest heat release and average apparent activation energy and Wax Residue 3 having the highest heat release and average apparent activation energy. These findings suggest that Wax Residue 1 has a higher tendency for spontaneous combustion. This research provides a scientific basis for the safety management of the coal chemical industry, and further exploration into the storage and handling methods of wax residues could reduce fire risks in the future.

Comparison of the pyrolysis behavior of PC, ABS and PC/ABS

Three types of plastics—polycarbonate (PC), acrylonitrile-butadiene-styrene (ABS), and PC/ABS blend—were studied in this work. Kinetic analyses were performed using the Flynn-Wall-Ozawa (FWO) and Kissinger–Akahira–Sunose (KAS) methods. The evolved volatiles during the pyrolysis of each material were analyzed, and the pyrolysis behavior was proposed using in-situ tools such as thermogravimetric analyzer-Fourier transform infrared spectroscopic (TG-FTIR) and gas chromatographic separation and mass spectrometry detection (Py-GC/MS). The three samples were also pyrolysed in a fixed bed reactor to elucidate the impact of secondary reaction. For PC, the activation energy increases as the reaction progresses. PC primarily generated CO2 and oxygenated compounds. For ABS, the activation energy experienced a slight decrease once the depolymerization reaction initiates, while a reversed trend can be observed at higher conversion rates. ABS pyrolysis mainly produced nitrogen-containing compounds and mono-aromatics. In the case of PC/ABS blend, a distinctive two-stage decomposition mechanism was observed. The interaction between PC and ABS in the blend promoted the formation of N/O-containing compounds. Additionally, this interaction enhanced the production of lighter phenols at the expense of bisphenol A, while ABS was not affected markedly. Stronger re-condensation and cracking reactions in the fixed bed system, facilitated the formation of poly-aromatics and lighter phenols (p-cresol and 4-ethylphenol) at the expense of bisphenol A during the pyrolysis of PC. In contrast, styrene from ABS decomposition was weakly affected by the secondary reaction. The intensified secondary reactions occurring the sample bed of the fixed bed experiments can also enhance the interaction between volatiles from ABS and PC, forming more heterocyclic N-compounds.

Bioenergy potential from Ecuadorian lignocellulosic biomass: Physicochemical characterization, thermal analysis and pyrolysis kinetics

Lignocellulosic biomass offers a sustainable and renewable method for producing high-quality fuels and value-added chemicals. In this study, residues from peach palm (top, inner sheath, and meristem), sugarcane (top), and pineapple (mother plant) were characterized based on their physicochemical properties and thermal degradation behavior to estimate their bioenergy potential. The biomass residue kinetic constraints were analyzed using three isoconversional models: the Flynn–Wall–Ozawa (FWO), Kissinger–Akahira–Sunose (KAS), and differential Friedman (DF) models. Physicochemical characterization showed the peach palm top's notably high cellulose content of 35.71 ± 0.47 % wt. Calorific values of the residues ranged from 13.73 ± 0.08 to 16.91 ± 0.90 MJ kg−1. X-ray diffraction analysis indicated the carbonaceous and crystalline nature of the biomass residues. Mean activation energy values ranged from 105.02 to 370.10 kJ mol−1 for KAS, 111.50–360.99 kJ mol−1 for FWO, and 108.60–360.27 kJ mol−1 for DF. Finally, thermodynamic analysis revealed the endothermic nature of the pyrolysis process across the entire conversion range for the samples. Overall, these samples demonstrate major potential as feedstock for biorefineries and the development of Ecuador's circular economy.

Insights into catalytic co-pyrolysis of spent coffee grounds and high density polyethylene (HDPE) using acid mine drainage (AMD) treated sludge based catalyst: Analysis of kinetics, mechanism and thermodynamic properties

The present study aims to investigate the catalytic effect of acid mine drainage (AMD) treated sludge based catalyst on the co-pyrolysis of spent coffee grounds and HDPE. The sludge was generated during the treatment of AMD using eggshell and hydrogen peroxide. Theromogravimetric analysis of pyrolysis of spent coffee grounds (SC), HDPE (High density polyethylene), blend of spent coffee grounds and HDPE (SC+HDPE) in the ratio of 1:1, and blended feedstock with sludge derived catalyst (SC+HDPE_AMDC) (1:1 wt. ratio) was conducted at various heating rates of 10 °C/min, 20 °C/min, 30 °C/min and 40 °C/min respectively. Iso-conversional models such as Ozawa Flynn Wall (OFW), Kissinger Akahira Sunose (KAS), Friedman, and Starink were utilized for the determination of activation energy (Ea) of the process. The results showed that using AMD treated sludge based catalyst to the pyrolysis process, enhances its overall efficacy by lowering the activation energy (Ea) (OFW- Ea: 209.11 to 177.14 KJ/mol, KAS-Ea: 208.30 to 173.06 KJ/mol, Friedman- Ea:210.54 to 176.28 KJ/mol, and Starink- Ea:208.60 to 173.44 KJ/mol). Criado's z-master plot (CZMP) method was utilized to analyze the mechanism of the reaction. The pre-exponential factor and thermodynamic parameters were also evaluated. It is concluded that the incorporation of sludge based catalyst (AMDC) lowered enthalpy and randomness of system. Catalytic co-pyrolysis requires less energy, making it more environmental friendly choice for the sustainable processing of biomass and plastics. The present investigation will aid in the design, optimization and scalability.

Holistic approach for sequential transesterification and pyrolysis of microalgal biomass: Kinetic and thermodynamic analysis of pyrolysis using model-free and model-based approaches

Due to the renewability and sustainability, biofuels derived from algae are considered as competitive substitutes for fossil fuels. Present study investigated a holistic approach for sequential transesterification and pyrolysis of microalgal biomass, i.e. Chlorella minutissima. This study explores the complete utilization of algal biomass through sequential chemical (transesterification) and thermochemical (pyrolysis) processes. First, the lipids were extracted and converted to eco-friendly biodiesel using catalytic route. Then lipid-extracted microalgae were pyrolyzed via thermogravimetric analyzer at four heating rates, namely 5, 10, 20 and 30 °C/min. The model-free isoconversional Kissinger-Akahira-Sunose (KAS), Flynn-Wall-Ozawa (FWO), and Vyazovkin models were used to analyze the kinetics and thermodynamics of algal pyrolysis. The activation energy obtained for the pyrolysis of Chlorella minutissima utilizing KAS, FWO and Vyazovkin were 146.78, 148.86, 147.11 kJ/mol, respectively. Positive ΔH values from KAS, FWO, and Vyazovkin show an endothermic nature of the process. The mean ΔH was found to be 142.81, 143.97, and 142.82 kJ/mol, while the ΔG was 151.9, 152.20, and 161.40 kJ/mol, respectively for KAS, FWO, and Vyazovkin approaches, at 10 °C/min heating rate. Importantly, this study also revealed that the phase interfacial model was the most appropriate model to represent the degradation process using Coats-Redfern method at 5 oC

Study on organic carbon in medium-low mature shale oil reservoirs rich in type II kerogen: Oxidation behavior, thermal effect, and kinetics

In-situ combustion technology (ISC) was a potential technology for efficient development of medium–low maturity shale oil reservoirs. Clarifying the exothermic behavior of organic carbon oxidation will be beneficial for better control of ISC processes. In this work, the organic carbon composition, type II kerogen and residual oil, were separated and extracted from the shale samples of typical medium–low maturity shale oil reservoirs in the Ordos Basin, China. The synchronous thermal analyzer and mass spectrometry (STA-MS), Fourier transform infrared spectroscopy (FTIR), and ROCK-EVAL VI were used to study the products, heat release, and functional group changes of type II kerogen, residual oil, and shale during the oxidation process. The results indicated that the oxidation heat release of shale mainly came from the oxidation reaction between its residual oil and type II kerogen, but the oxidation heat release range of shale was relatively lagging compared to the single residual oil or type II kerogen affected by rock debris. Secondly, under atmospheric pressure, the type II kerogen experiences obviously higher heat release than residual oil and heavy oil, indicating its superior potential of in-situ heat release. In addition, the major productions that CO, H2O, SO2, and CO2 were quantitatively characterized, with CO2 having the highest production of 882.25 mg/g. Furthermore, combined with the molecular weight, an oxidation reaction equation of type II kerogen was constructed. Finally, the oxidation kinetics parameters of type II kerogen, residual oil, and shale were determined using Friedman and Ozawa-Flynn-Wall (OFW) models. It was found that the activation energy of shale was higher than II kerogen and residual in low temperature oxidation (LTO) and fuel deposition (FD) stages. This may be due to the joint reaction between kerogen and residual oil, thus exacerbating the challenge of shale in-situ ignition. However, due to the catalytic effect of rock debris, the activation energy of shale was lower than LTO in high temperature oxidation (HTO) stage, indicating that once fuel deposition was completed, organic carbon will undergo stable combustion. This study has theoretical guidance for the numerical simulation research of ISC development technology of maturity-low shale oil reservoirs.

Thermal degradation of capsaicin and dihydrocapsaicin: Mechanism and hazards of volatile products

Food safety issues have become unprecedentedly notable. To ensure the safe use of capsaicin (CAP) and dihydrocapsaicin (DHCAP) in the food sector, their thermal degradation characteristics was examined for the first time through thermogravimetric analysis (TGA) and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) analysis. The second major phase occurred within the temperature range of 265–425 ℃, leading to substantial weight reductions of 96.13 % for CAP and 92.76 % for DHCAP. Thermodynamic parameters, calculated using the Flynn–Wall–Ozawa (FWO), Kissinger–Akahira–Sunose (KAS), and Coats–Redfern (C–R) methods, indicated that the thermal decomposition of both CAP and DHCAP was non-spontaneous and followed an F1 mechanism (−ln(1−α)). The pyrolysis of CAP and DHCAP released several volatile compounds, including CAP, DHCAP, Z-9-octadecenamide, octadecanamide, 9-decenenitrile, nonanenitrile, and 8-methylnonanoic acid. These compounds may pose certain toxicological risks and potential hazards to human health. The pyrolytic pathways for CAP and DHCAP are likely to involve the cleavage of alkyl C-N and/or amide bonds, as well as processes of deamidation and demethylation. Therefore, it is prudent to avoid heating food containing CAP and DHCAP above 265 ℃ during culinary preparation.

Co‐Pyrolysis and Pyrolysis of Corn‐Cob Biomass and Waste Plastic: Comprehensive Study Based on Kinetic and Thermodynamic Approach

AbstractThis study focuses on the utilization of agro‐residual corn‐cob biomass, waste plastic and the combination of both for pyrolysis reaction using thermal analysis. Circular bioeconomy is assured by closing all the resource materials loops through co‐pyrolysis process. The conversion profiles of corn cob pyrolysis at various heating rates reveal a three‐stage decomposition process, and plastic waste exhibits single stage degradation. Due to the interaction between the blended materials, additional degradation peaks arise during the co‐pyrolysis of waste plastic (PET bottles) and biomass (corn cobs). The apparent activation energy fluctuates in the range of 120–260 kJ/mol with the conversion, according to Flynn‐Wall‐Ozawa (FWO) and Kissinger‐Akahira‐Sunose (KAS) kinetic methods. Notably, for co‐pyrolysis the apparent activation energy is lower (168 kJ/mol using FWO) than the individual biomass (179 kJ/mol using FWO) and plastic (175 kJ/mol using FWO), suggesting a positive synergistic effect during charring. The liquid crude and char product analysis from corn cob pyorlysis through FTIR and XRD confirms the application of the products in energy and chemical processes. The results obtained in this study can be utilized for co‐pyrolysis reactor analysis specifically using waste plastic bottles that are accumulating in the environment.

Pyrolysis kinetics of waste ryegrass under nitrogen and air atmosphere

To investigate the pyrolysis reaction of ryegrass, we conducted a simultaneous thermal analysis using thermogravimetric(TG) analyzers. This involved obtaining data through Thermogravimetry (TG), Derivative Thermogravimetry (DTG), and Differential thermal analysis (DTA) techniques. The experiments were conducted under dynamic nitrogen and air atmospheres at different heating rates. The kinetic parameters of ryegrass pyrolysis were determined using the Kissinger method, the Flynn-Wall-Ozawa (FWO) peak conversion rate approximate equivalence method, the Flynn-Wall-Ozawa (FWO) equal conversion rate method, and the Škvára-Šesták (S–S) method. It provides a theoretical basis for the reuse of ryegrass resources. The findings indicated that the pyrolysis temperature of ryegrass increased with the accelerated rate of temperature increase in both atmospheres. The average weight loss rate of pyrolysis of ryegrass in the air atmosphere (92.27 %) is higher than that compared to that in a nitrogen atmosphere (86.11 %). Additionally, the temperature required for complete decomposition is lower in the former case. The FWO peak conversion rate approximation equivalence approach and the FWO equal conversion rate method do not apply to the solution of the pyrolysis activation energy of ryegrass. The pyrolysis activation energy for the two decomposition stages, as calculated by the Kissinger method, is 165.73 and 185.86 kJ/mol−1 in the air atmosphere, and 219.99 and 277.02 kJ/mol−1 in a nitrogen atmosphere, respectively. The activation energy and mechanism function of ryegrass pyrolysis calculated by using the S–S method are as follows: [−ln(1−α)]2, 119.79, 104.31, 95.75, and 91.93 kJ/mol−1 in air atmosphere, (1−α)−1, 176.64, 67.89, 61.15, and 54.25 kJ/mol−1 in nitrogen atmosphere, respectively. The activation energy of ryegrass pyrolysis, as determined by both the Kissinger method and S–S method, was found to be higher under an air atmosphere compared to a nitrogen atmosphere.

Pyrolysis of high-density polyethylene: Degradation behaviors, kinetics, and product characteristics

Pyrolysis is a promising technology for converting plastic waste into valuable raw materials while offering a potential solution to the global plastic pollution crisis. In this study, the thermal pyrolysis of high-density polyethylene (HDPE) is investigated in a drop tube reactor under nearly isothermal conditions. The impact of reaction temperature and gas/volatile residence time on carbon conversion and product distribution is examined across a range of 500–900 °C and 3.6–32.2 s, respectively. Non-condensable gas products detected by online mass spectrometry are H2, CH4, C2H4, C2H6, C3H6, and C3H8. At elevated temperatures and prolonged residence time, H2 yield reaches as high as 8.6 wt% of the initial HDPE mass due to intensified cracking reactions of C2–C3 hydrocarbons and long-chain aliphatic compounds. Consequently, pyrolysis tars consist mainly of polycyclic aromatic hydrocarbons (PAHs) with 5–7 rings, accompanied by visible coke deposition within the reactor. HDPE decomposition to volatiles is an endothermic process and it is complete at a temperature between 492 °C and 525 °C, depending on the heating rate employed, from non-isothermal thermogravimetric analysis and differential scanning calorimetry (TGA-DSC) measurements. The thermal degradation of HDPE pellets follows the two-dimensional nucleation growth model for conversion levels up to 0.8 with an apparent activation energy of 259–270 kJ/mol and a pre-exponential factor of 4.83 × 1017–1.37 × 1019 min−1, determined from various isoconversional methods such as Flynn-Wall-Ozawa (FWO), Kissinger-Akahira-Sunose (KAS), and Starink, along with Criado's master plots. These findings provide valuable insights into optimizing process parameters and refining reactor design for pyrolysis, which can be integrated with gasification and reforming processes to enhance hydrogen production on a larger scale.

Pyrolysis behavior of densified refuse-derived fuels (d-RDFs) via TGA: Investigating the impact of densification degree on thermal kinetics and thermodynamics

The conversion of municipal solid waste (MSW) into its energy-rich fraction, known as refuse derived fuel (RDF), addresses both MSW management and energy demand. RDF comprises a diverse blend of various non-hazardous waste streams, making it challenging to predict physical properties and chemical compositions. However, densification can help overcome these challenges. This work aims to explore the effect of densification degree on kinetic and thermodynamic parameters during the degradation of densified refuse-derived fuels (d-RDFs) in inert atmosphere. Herein, three d-RDFs samples obtained with varying degree of densification and die temperatures ranging from 55 °C to 118 °C, as well as a mixed fines (MF) sample produced during the pelletization process, were analyzed. Pyrolysis potential of d-RDFs and MF were determined using thermogravimetric analysis in the temperature range from 30 to 800 °C, at multiple heating rates of 5, 10, and 20 K min−1. The effect of the degree of densification on physical characteristics, and kinetic and thermodynamic parameters of d-RDF was investigated. Apparent activation energy (Eα) was estimated employing Friedman (FR), Kissinger-Akahera-Sunnose (KAS), and Flynn-Wall-Ozawa (FWO) methods. Derived Eα values were used to determine the pre-exponential factor (Aα) using the Kissinger method. Experimental results revealed that the durability of d-RDFs increased from 79.26 % to 98.73 % as the densification degree increased from II to IX. Furthermore, the Eα values exhibited a decreasing trend in the first peaks of the DTG profiles, while an opposite trend was observed in the second peaks of DTG curves. However, with an increase in the degree of densification, the mean values of Eα decreased by 5–10 % for all methods. The Aα values, assessed using the FR method, surpassed the critical value of (109 s−1) for all samples. However, with the KAS and FWO methods, these values fell below (109 s−1) within the conversion range of 0.05–0.25. Thermodynamic parameters confirmed the endothermicity of the thermal degradation process.

Investigation of Combustion and NO/SO2 Emission Characteristics during the Co-Combustion Process of Torrefied Biomass and Lignite.

This paper investigates the combustion characteristics and pollutant emission patterns of the mixed combustion of lignite (L) and torrefied pine wood (TPW) under different blending ratios. Isothermal combustion experiments were conducted in a fixed bed reaction system at 800 °C, and pollutant emission concentrations were measured using a flue gas analyzer. Using scanning electron microscopy (SEM) and BET (nitrogen adsorption) experiments, it was found that torrefied pine wood (TPW) has a larger specific surface area and a more developed pore structure, which can facilitate more complete combustion of the sample. The results of the non-isothermal thermogravimetric analysis show that with the TPW blending ratio increase, the entire combustion process advances, and the ignition temperature, maximum peak temperature, and burnout temperature all show a decreasing trend. The kinetic equations of the combustion reaction process of mixed gas were calculated by Flynn-Wall-Ozawa (FWO) and Kissinger-Akahira-Sunose (KAS) kinetic equations. The results show that the blending of TPW reduces the activation energy of the combustion reaction of the mixed fuel. When the TPW blending ratio is 80%, the activation energy values of the mixed fuel are the lowest at 111.32 kJ/mol and 104.87 kJ/mol. The abundant alkali metal ions and porous structure in TPW reduce the conversion rates of N and S elements in the fuel to NO and SO2, thus reducing the pollutant emissions from the mixed fuel.

Thermal stability and decomposition kinetics of polybenzoxazine and oligomeric polyhedral octaphenyl silsesquioxane nanocomposites

AbstractIn this study, the impact of octaphenyl polyhedral oligomeric silsesquioxane (POSS) on the thermal stability of polybenzoxazine resin at 1, 3, and 5 wt% POSS loading through dynamic thermogravimetric analysis (TGA) at heating rates of 10, 20, 30 and 40°C min−1 was investigated. Besides, the decomposition kinetics of polybenzoxazine resin (PBZ) and various nanocomposites were studied using Kissinger, Friedman, Flynn‐Wall‐Ozawa (FWO) and Coats‐Redfern (CR) models and also, the activation energies of samples were calculated. At first, benzoxazine monomer was synthesized and then nanocomposites were prepared via solution mixing method. The qualitative dispersion of nanoparticles in benzoxazine resin was examined through the utilization of scanning electron microscopy and x‐ray diffraction experiments. The results showed that the addition of nanoparticles improved the thermal stability of PBZ resin specially at 1 wt% POSS loading and at higher POSS content the thermal stability of the resin decreased. As determined by TGA, the char yield of resin was enhanced by 2.6% upon the addition of 1 wt% nanoparticles. In addition, in 1 weight percent of nanoparticles, as the heating rate rose from 10 to 40°C min−1, the Integral Program Decomposition Temperature (IPDT) has increased by about 260°C, and this increase is about 183°C compared to the resin, and also elevating the heating rate, Td (5%) and Td (10%) weight loss of samples shifted to higher temperatures. The degradation mechanism of the resin and nanocomposites was evaluated through Kissinger, Friedman, FWO and CR models. The results displayed that the addition of 1 wt% nanoparticles increased the activation energy (Ea) values of the nanocomposites compared to that of neat resin and above this filler content, the Ea values decreased. The findings derived from the FWO model indicated that the inclusion of a 1 wt% filler raised the Ea values of the first and second stages of PBZ resin decomposition from 136–200 and 151–214 kJ mol−1 to 148–210 and 180–228 kJ mol−1, respectively.

Co-pyrolysis of phenolic printed circuit boards with CaO and Ca(OH)2 mixture in a fluidized bed reactor: Optimization of the operating conditions and the kinetic analysis

In a previous study (Haghi et al., 2023), we demonstrated that co-pyrolysis of paper-laminated phenolic PCB (FR2-PCB) with a mixture of CaO and Ca(OH)2 in a fluidized bed reactor results in the simultaneous enhancement of the production of the pyrolysis oil and a significant decrease in its halide content. To advance the utilization of a blend of CaO and Ca(OH)2 for scaling up the pyrolysis of FR2-PCB beyond laboratory-scale pyrolyzers, especially in fluidized bed reactors renowned for their effectiveness in large-scale pyrolysis of polymeric materials, the optimal operating conditions, as well as the kinetic parameters in the presence of CaO and Ca(OH)2 should be explored. To this end, this study focuses on optimizing the temperature (T), retention time (t), and PCB-to-additive ratio (FR2/A) as the parameters controlling the co-pyrolysis of paper-laminated phenolic PCB (FR2-PCB) with a 50:50 mixture of CaO and Ca(OH)2 in a fluidized bed reactor. According to the results of the experiments designed based on the response surface methodology, the maximum recovery of pyrolysis oil (40.6 %) was obtained at T = 620 °C, t = 22 min, and FR2/A= 5.4 g/g. Additional tests were carried out to explore the impact of CaO+Ca(OH)2 concentration on the halogen content of the pyrolysis products. Furthermore, the thermogravimetric analysis (TGA) was performed to investigate the influence of the tested additives on the pyrolysis behavior and the kinetic characteristics of FR2-PCB. By employing three iso-conversional model-free approaches, i.e., the Kissinger-Akahira-Sunose (KAS), Flynn-Wall-Ozawa (FWO), and Starink integral methods, it was found that adding CaO+Ca(OH)2 to FR2-PCB can reduce the activation energy of the pyrolysis reactions by 20 %.

Non‐isothermal Thermogravimetric Analysis of Peltophorum pterocarpum and Evaluation of Kinetic Triplet

AbstractThe primary focus of the twenty‐first century has been on developing new and cleaner fuels from renewable sources. The increasing availability of renewable energy sources in environment, such as lignocellulosic biomass derived from agricultural and forest residues, has created a plethora of opportunities for biofuel production. For this purpose, the search for appropriate waste biomass source and the design of suitable reactors are very essential, where the latter requires the knowledge of kinetic triplets. These requirements paved the way to the novelty of the present work as a selection of a rarely used biomass source, that is, Peltophorum pterocarpum, and its non‐isothermal thermogravimetric analysis for the evaluation of kinetic triplet of the process. The range of temperature is 298–1173 K attained at heating rates of 10–55 K min−1. Kinetics were estimated using differential Friedman method (DFM), distributed activation energy method (DAEM), Ozawa–Flynn–Wall (OFW), Kissinger–Akahira–Sunose (KAS), and Starink (STK) models. Mean activation energy (kJ mol−1) and pre‐exponential factor (min−1) of pyrolysis process by five models were 183.68 and 1.24 × 1017 for DAEM, 194.28 and 3.08 × 1021 for DFM, 183.68 and 4.40 × 1016 for KAS, 184.12 and 2.12 × 1014 for OFW, and 183.93 and 3.56 × 1016 for STK. Average values of changes in Gibbs free energy, enthalpy, and entropy by five models are 174 kJ mol−1, 178 kJ mol−1, and 0.007 kJ mol−1 K−1, respectively. Criado's master plots revealed distinct reaction pathways during the process for different conversion levels.

Pyrolysis of multilayered plastic packets to hydrocarbon fuel feedstock: Thermal degradation behaviour, kinetics and thermodynamic analysis, and semi-batch studies

This study examines the kinetics and batch pyrolysis behavior of multilayered waste milk packets to optimize their conversion into valuable products. Using thermogravimetric analysis at heating rates of 5, 10, 15, and 20 °C/min and employing the model fitting and model-free methods such as the Kissinger-Akahira-Sunose (KAS), Flynn-Wall-Ozawa (FWO), and Kissinger methods, the process was found to follow an F1 order-based mechanism with an activation energy of 304 kJ/mol and a pre-exponential factor of 2.60 × 1012 min.−1 The maximum weight loss (97.2 %) occurs at 5 °C/min. The average changes in free energy, enthalpy, and entropy are 814.939 kJ/mol, 135.698 kJ/mol, and −903.846 × 10−3 kJK−1mol−1 respectively. At 450 °C, the maximum pyrolytic oil yield reaches 66.92 %, with FTIR analysis confirming the presence of diverse hydrocarbon components such as alkanes, alkenes, cycloalkanes, aromatic hydrocarbons etc. in the oil. Kinetic triplet and thermodynamic parameter data, alongside physical and chemical analyses, suggest that the pyrolytic oil from multilayered waste milk packets could serve as a superior substitute for petrochemical fuel oil.