Pyrolysis Kinetic Parameters Research Articles

Energy Utilization of Building Insulation Waste Expanded Polystyrene: Pyrolysis Kinetic Estimation by a New Comprehensive Method.

Expanded polystyrene (EPS) has excellent thermal insulation properties and is widely applied in building energy conservation. However, these thermal insulation materials have caused numerous fires because of flammability. Pyrolysis is necessary to support combustion, and more attention should be paid to the pyrolysis characteristics of EPS. Moreover, pyrolysis is considered to be an effective method for recycling solid waste. Pyrolysis kinetics of EPS were analyzed by thermogravimetric experiments, both in nitrogen and air atmospheres. A new method was proposed to couple the Flynn–Wall–Ozawa model-free method and the model-fitting method called the Coats–Redfern as well as the particle swarm optimization (PSO) global algorithm to establish reaction mechanisms and their corresponding kinetic parameters. It was found that the pyrolysis temperature of EPS was concentrated at 525–800 K. The activation energy of EPS in nitrogen was about 163 kJ/mol, which was higher than that in air (109.63 kJ/mol). Furthermore, coupled with Coats–Redfern method, reaction functions g(α) = 1 − (1 − α)3 and g(α) = 1 − (1 − α)1/4 should be responsible for nitrogen and air reactions, respectively. The PSO algorithm was applied to compute detailed pyrolysis kinetic parameters. Kinetic parameters could be used in further large-scale fire simulation and provide guidance for reactor design.

Investigating Waste Plastic Pyrolysis Kinetic Parameters by Genetic Algorithm Coupled with Thermogravimetric Analysis

Pyrolysis of waste plastic (WP) is a promising method to solve the plastic pollution issue. WP is mainly composed of polyethylene (PE). Moreover, the products of waste polyethylene (WPE) pyrolysis could serve as high quality fuels and the feedstocks of petrochemicals. Therefore, it is essential to investigate the WPE and WP pyrolysis process. This study evaluates pure PE, WPE and WP pyrolysis kinetic parameters by the use of genetic algorithm (GA) and isoconversional methods coupled with thermogravimetric analysis (TGA), respectively. Additionally, three representative reaction models, i.e. reaction-order, extended Prout–Tompkins and Sestak–Berggren models, are investigated for obtaining the most suitable model, which could describe the PE, WPE and WP pyrolysis process more accurately. Consequently, the reaction-order model turns out to be the optimal method for appropriately describing PE, WPE and WP pyrolysis processes. Hence, the pyrolysis parameters optimized by GA are proven to be accurate and reliable, in comparison of calculated values of activation energy by isoconversional methods and experimental data. Moreover, it might be applicable of GA coupled with TGA with reaction-order model to the future industrial WPE and WP pyrolysis circumstances that have variable heating rates.

Evaluation of models to predict the influence of chemical pretreatment on the peels of Nephelium lappaceum L. based on pyrolysis kinetic parameters obtained using a combined Fraser-Suzuki function and Friedman’s isoconversional method

In the present work, two chemometric strategies were evaluated to assess the influence of the chemical pretreatment: a Kohonen self-organizing map neural network and a Support Vector Machine Learning algorithm. Kohonen ANN was able to predict the influence of chemical treatment mainly on pseudo-component lignin, since cellulose and hemicellulose have similar structures; presenting a topological error of 0.044 and a quantification error of 0.193, while the Vector Supporting Machine (SVM) algorithm was able to predict the classes with accuracy of 0.956, area under the ROC curve (AUC) of 0.992 and F1 score of 0.956, proving to be a more effective strategy in predicting the influence of the chemical treatment on the rambutan shells based on the kinetic parameters. It was also observed an increase in the activation energy for the cellulose pretreated with sodium hydroxide and with phosphoric acid, mainly due to the partial conversion of type I cellulose into type II cellulose, ranging from 152 to 155 kJ/mol versus 124 kJ/mol for the untreated sample. The thermal decomposition mechanism did not change significantly, being estimated as pseudo-zero order, using the Master-Plot method. TG-FTIR analysis reveals that the main gases emitted during pyrolysis are CO2, H2O and CO, being the carbon dioxide-related band an indicator of the influence of the chemical treatment. This analysis also reveals the release of sulfur compounds from the sample treated with sulfuric acid, indicating that the environmental point of view of this sample shows no viability as use as pyrolysis feedstock.

Automated fitting of thermogravimetric analysis data

SummaryA novel methodology has been developed for extracting pyrolysis kinetic parameters from thermogravimetric analysis (TGA) data. The development of this methodology is motivated by a need to automate the determination of material properties for use in fire models. The algorithm with which the methodology is implemented is described. Aside from being fully automated, the resultant script has the advantage of being efficient—a full set of kinetic parameters is provided in less than 1 second. The script is verified against manufactured TGA data for one and two reaction mechanisms and the effects of reaction peak width and the distance between reaction peaks is examined. Validation is accomplished by applying the script to TGA data for Nylon 6,6, a flexible polyurethane foam, and polyvinyl chloride. The resultant kinetic parameters are tabulated, and plots of the actual and predicted TGA data show that the algorithm is quite effective for one, two, and three reaction mechanisms.

Thermogravimetric analysis and reaction kinetics of lignocellulosic biomass pyrolysis

The elucidation of the biomass pyrolysis characteristics will provide valuable guidance for the design of pyrolysis devices. The pyrolysis kinetics characteristics of lignocellulosic biomass were studied by thermogravimetric analysis, and the main influencing factors, including biomass particle size, heating rate, and metal ion, were investigated. With a decrease in the particle size of rice straw and pine sawdust, the initial and final pyrolysis temperatures and the temperature of the maximum weight loss ratio decreased. Opposite results were obtained for Phoenix tree leaves. Furthermore, the initial release temperature of volatile matter and the temperature corresponding to the peak of the derivative thermogravimetric curves increased with an increase in heating rate. Moreover, the pyrolysis activity of rice straw decreased significantly after deashing but increased with the addition of potassium. The pyrolysis kinetics parameters were calculated by the Coats–Redfern, Doyle, and the distributed activation energy model (DAEM) methods. The apparent activation energy of pyrolysis was the lowest, varying between 30 and 70 kJ/mol, according to the fitting results of the Coats–Redfern method. The apparent activation energies calculated by the DAEM and Doyle methods are similar, and are 67.6, 245.8, and 271.8 kJ/mol for rice straw, pine sawdust and Phoenix tree leaves, respectively.

Evaluation on isothermal pyrolysis characteristics of typical technical solid wastes

Isothermal pyrolysis characteristics of typical technical solid wastes (polyethylene, paper towel and textiles, and their mixture with a blending ratio of 4:1:1) were carried out in a fixed bed between 475 °C and 550 °C. The influence of the temperature on the pyrolysis index, kinetic parameters and products of the samples was addressed. The interaction between the three individuals during their co-pyrolysis was identified. As the temperature was from 475 °C to 550 °C, the pyrolysis index of the polyethylene increased by about 78 times, while that for paper towel and textiles only increased by about 1 and 6 times, respectively. Solid residues from the mixture pyrolysis were about 11.6 % wt. More alkanes and alkenes were in liquid products of the mixture. The shrinking core model would represent well the mixture pyrolysis. The pre-exponential factor of polyethylene was much higher than other two individuals. There was a significant synergistic effect detected for mixture during the co-pyrolysis. The pyrolysis of mixture was dominated by a third order reaction mechanism. This study can provide basic data for the thermal treatment of solid waste in nuclear power plants.

Grindability, thermogravimetric characteristics, and kinetics analysis of semi‐biochar from coarse wood pyrolyzed in a fluidized bed

AbstractFor the utilization of leftover materials from furniture factory, a two‐step pyrolysis, an initial treatment at mild temperature followed by a fast pyrolysis step, in a fluidized bed reactor was proposed in this study. The grindability of semi‐biochar samples after the mild temperature pyrolysis was studied. The fast pyrolysis characteristics and kinetics parameters of the semi‐biochar samples were also investigated by thermogravimetric analysis. Results showed that an improvement in the grindability characteristics was observed. The grinding of semi‐biochars that do not completely devolatilize mainly produces a mixture of fine particles and small fragments, whereas the semi‐biochars that completely devolatilize have good grinding characteristic, and the main ground products are short and round particles. Most differential thermogravimetric (DTG) curves of the semi‐biochar samples presented two peaks and four common stages. With increase of the temperature or residence time in mild temperature treatment process, the decomposition intensity of hemicellulose and cellulose in grinding residues decreased gradually, while the decomposition intensity of lignin changed little. Peak DTG value ranging from 4%/min to 6%/min can be adopted to estimate the optimal operation condition for mild temperature pyrolysis. Three‐dimensional diffusion model can accurately describe the fast pyrolysis of semi‐biochar.

Assessment of the thermal pyrolysis characteristics and kinetic parameters of spent coffee waste: a TGA-MS study

ABSTRACT The present study aimed to investigate the pyrolysis characteristics and kinetics of spent coffee waste (SCW) at different heating rates (5–40 °C/min) at a temperature ranging from 30 to 800°C in a thermogravimetric analyzer (TGA). First, the physicochemical properties of the SCW were characterized using X-ray diffraction, Fourier transform infrared spectrometry, scanning electron microscopy, and elemental analysis. Then, the thermal decomposition kinetic profiles were modeled using the Coats–Redfern, Flynn–Wall–Ozawa (FWO), Kissinger–Akahira–Sunose (KAS), and Starink models. All the tested models provided accurate fits of the thermogravimetric analysis data with acceptably high R 2 values. The mean activation energy of the coffee waste was 101.8, 96.7, and 97.1 kJ/mol for the FWO, KAS, and Starink models, respectively. Finally, the evolved gases detected during the decomposition by TGA coupled with a mass spectrometer (MS) primarily consisted of water, methane, and carbon dioxide.

Термическая переработка древесных отходов

Describes the processes of thermal conversion of soft– and hardwood waste to obtain gaseous, liquid and solid products. During the initial stage of the work, the thermogravimetric study of initial samples of birch and pine sawdust was performed in the temperature range from 35 to 1000 °C. On the basis of the thermal analysis data obtained, a method of pyrolysis process of wood waste in the temperature range of 400–500 °C in an inert environment was developed. As a result of experiments on pyrolysis of wood waste, the dependence of the conversion of selected samples into final products, the properties of the resulting gaseous and solid carbon-containing products depending on the conditions of the process, the size of the fraction and the type of wood were obtained. It was found that the optimal temperature of the pyrolysis process in the studied range of system parameters is 450 °C, and the particle size of wood waste is 1–2 mm. Data on the molecular mass distribution of volatile pyrolysis products and kinetic parameters of the pyrolysis process were obtained. The activation energies of the pyrolysis process for pine and birch sawdust samples were 119.3 and 128.2, respectively. The specific surface area of the initial samples of birch and pine wood waste was 9.3 and 8.5 m2/g, respectively. The specific surface area of coal pyrolysis residues for hardwoods increased by 2.4 times and for conifers by 2.1 times, respectively, and assumed values of 22.3 and 17.9 m2/g. Therefore, the coal residues of pyrolysis of wood waste can potentially be used as raw materials for the production of activated carbons and carbon sorbents of various applications.

Kinetics of pyrolysis and gasification of cotton stalk in the central parts of India

The paper presents a detailed study on both, pyrolysis and gasification of cotton stalk, investigated using Thermo-gravimetric Analyser (TGA) and a fixed bed reactor. The pyrolysis experiments are conducted at different heating rates over a range 5–30 K/min in an inert medium. Pyrolysis reactions are observed to be dependent on the operating condition and chemical composition confirmed by FTIR analysis. Gas evolution kinetics during pyrolysis process and tar formation are also studied in a specially designed fixed bed reactor. CO2-char gasification experiments are conducted at different temperatures over a range of 973–1123 K. The char gasification reaction is observed to be dependent on char surface area and inorganic content of biomass. The kinetic parameters for pyrolysis are estimated using model-free/model-fitting methods such as Kissinger-Akahira-Sunose (KAS), Flynn-Wall-Ozawa (FWO), Coats-Redfern (CR), Single Reaction Model (SRM), and Distributed Activation Energy Model (DAEM). The kinetic parameters for CO2 gasification are estimated using Random Pore Model (RPM) and Modified RPM.

Influence of torrefaction pretreatment on corncobs: A study on fundamental characteristics, thermal behavior, and kinetic

The effects of torrefaction pretreatment on corncobs properties and its pyrolysis kinetic parameters were investigated in this study. Proximate and ultimate analyses indicated that torrefaction increased the H/Ceff ratio and higher heating value of corncobs, and reduced its oxygen content. Although the mass yield was also reduced, the corresponding energy yield was relatively higher. The crystallinity index of biomass showed a first upward and then downward trend with the torrefaction temperature. Kinetic parameters obtained from three models indicated that both the activation energy and the pre-exponential factor increased with the elevated torrefaction temperature and it's better to calculate the activation energy by the OFW method and to use the KAS and DAEM methods to calculate the pre-exponential factor. In addition, it was found that the optimum pretreatment temperature of corncobs was 240 °C.

Reactive molecular dynamics simulation on thermal decomposition of n-heptane and methylcyclohexane initiated by nitroethane

Normal alkanes and cycloalkanes are important components of endothermic hydrocarbon fuels. The present work conducts the reactive molecular dynamics (RMD) simulations based on reactive force field to compare the thermal cracking of n-heptane and methylcyclohexane (MCH) with the same carbon atom number initiated by nitroethane, focusing on initial decomposition temperature, intermediates and product distribution, and the related kinetics. From the RMD simulations, we find nitroethane can accelerate both n-heptane and MCH decompositions, since the C–NO2 bond rupture of nitroethane can proceed at relatively lower temperatures to produce the reactive radicals compared to the C–C bond cleavage of n-heptane and MCH to start the free radical chain reactions, but the promoting effect becomes weaker after it reaches a certain level with temperature. Reasonable Arrhenius parameters estimated from RMD simulations based on first-order kinetic analysis compare well with experimental results. The observed difference of pyrolysis behaviors and kinetic parameters between n-heptane and MCH can be ascribed to their molecular structure, coinciding with experimental observations. In the presence of nitroethane, reductions of initial temperature and activation energy for n-heptane decomposition are larger than those for MCH decomposition. More alkenes are observed in n-heptane decomposition compared to MCH decomposition. Due to the endothermic capacities of fuel being sensitive to the yields of alkenes, more heat could be absorbed by the n-heptane decomposition. These results indicate that RMD simulations can provide important insights at the atomistic level on the difference of decomposition behaviors between normal alkanes and cycloalkanes initiated by nitroethane under supercritical conditions.

Characteristics of Corn Stover Components Pyrolysis at Low Temperature Based on Detergent Fibers.

In order to study the effect of biomass components on the low temperature (30–400°C) pyrolysis, the thermogravimetric analysis (TGA) of corn stover (CS) and its three detergent fibers (extracted by Van Soest method) were studied, and the model compounds of cellulose, hemicellulose and lignin were also tested as comparison. The results shows the low temperature pyrolysis index (P) is significantly different (PADL < Plignin < PCS < PNDF−CS < Pxylan < PADF−CS < Pcellulose). Klason-lignin has stronger thermal stability and decomposes more difficult than alkali lignin. The original cross-linked structure and interaction of the three components inhibited volatiles releasing, especially significant below 300°C. The synergistic effect between cellulose and lignin promoted devolatilization and decreased the initial temperature of cellulose decomposition. At last, the low temperature pyrolysis kinetics parameters (apparent activation energy and pre-exponential factor) of CS and its detergent fibers were calculated via the Coats-Redfern methods. This study can provide a theoretical basis for optimization of process conditions and industrial application of low temperature pyrolysis for lignocellulosic biomass.

Parametrization of a Modified Friedman Kinetic Method to Assess Vine Wood Pyrolysis Using Thermogravimetric Analysis

Common kinetic parameters were obtained for leached and non-leached samples of vine wood biomass. Both samples were considered to have different proportions of cellulose, hemicellulose, and lignin compositions as a result of the leaching process. The two samples were analyzed in terms of pyrolysis kinetic parameters using non-isothermal thermogravimetric analysis. Furthermore, the classic Friedman isoconversional method, a deconvolution procedure using the Fraser–Suzuki function, and a modified Friedman method from a previous study on the delay in conversion degree were satisfactorily applied. The observed difference when the deconvolution technique was applied suggests that the classic Friedman method is not adequate for studying the pyrolysis of individual vine wood biomass components. However, this issue was solved by studying the delay in conversion degree of both biomasses and calculating the kinetic parameters using the resulting information. This procedure was found to be useful for studying and comparing the kinetics of heterogeneous biomasses and has a sound scientific explanation, making this research a basis for future similar studies.

Pyrolysis kinetic study of waste milk packets using thermogravimetric analysis and product characterization

This work deals with the study of kinetic evaluation and pyrolysis of waste milk packets (polyethylene) for oil production. Thermogravimetric analysis (TGA) of waste milk packets was conducted in an inert atmosphere with heating rates of 5, 10 and 20 °C min−1 to analyse its thermal degradation behaviour. Pyrolysis kinetic parameters consist of activation energy and pre-exponentiation factor, and thermodynamic parameters include changes in Gibb’s free energy, enthalpy and entropy which were computed by Kissinger–Akahira–Sunose (KAS), Ozawa–Flynn–Wall (OFW) and Coats–Redfern methods using TGA data. The mean value of activation energy for pyrolysis of waste milk packets computed by KAS and OFW methods was 175.36 and 177.94 kJ mol−1, respectively, and the pre-exponential factors were found to be in the range of 1.37 × 1013–1.54 × 1014 min−1. Thermal pyrolysis of waste milk packets was performed in a semi-batch pyrolysis reactor. The maximum yield of oil was obtained as 45 wt% at pyrolysis temperature of 500 °C. The oil was analysed by ultimate analysis, Fourier transform infrared spectroscopy (FTIR) and gas chromatography–mass spectrometry (GC–MS). Chemical compounds present in oil were mainly paraffins, naphthenes and olefins with carbon number range of C9–C18. The boiling point of oil was found in the range of 63–360 °C.

Slow pyrolysis characteristics of bamboo subfamily evaluated through kinetics and evolved gases analysis

The objective of this study is to investigate the pyrolysis and kinetic characteristics of three varieties of the bamboo subfamily via thermogravimetry/Fourier transform infrared spectrometry (TG-FTIR) coupling technologies. The pyrolysis process can be divided into three stages of dehydration, volatilization, and carbonization. TG-FTIR analysis revealed that evolved gas is constituted by CO2, CO, CH4, H2O, NO, NO2, formic acid, HCN, and CO functional groups as major pyrolysis products. The kinetic parameters of pyrolysis were calculated using model-free methods of distributed activation energy (DAEM). With an increase in conversion, the activation energy of each bamboo subfamily exhibited distinct variations. The average values of activation energy for moso bamboo, bambusa multiplex, and black bamboo determined by DAEM were 201.59, 220.49, and 224.47 kJ/mol, respectively. Results of thermodynamic and kinetic analysis indicate that the bamboo subfamily shows great potential as an alternative fuel by pyrolysis.

Pyrolysis characteristics and kinetic analysis of rice husk

In this work, the thermo-gravimetric and differential thermo-gravimetric curves of rice husk at different heating rates (20, 40, 60, 80 and 100 °C min−1) were obtained using a thermo-gravimetric analyzer under nitrogen atmosphere. The pyrolysis characteristics of rice husk were analyzed. The fitted Gaussian function peaks showed that the pyrolysis mass loss of rice husk can be characterized by three independent reactions. The devolatilization index D was calculated, and the effect of different experimental statuses on the pyrolysis of rice husk was discussed. The kinetic parameters of rice husk were calculated using iso-conversional models and distributed activation energy models (DAEMs). The kinetic parameters obtained by differential Friedman method and integral Ozawa method were found to be 224.85 kJ mol−1 and 220.06 kJ mol−1, respectively. The apparent activation energies for pyrolysis were not fixed value and continuously fluctuated with the increase in conversion rate. The kinetic parameters, obtained using the Kissinger method, were relatively simple and could not represent the variation trends of variables. Six different probability density functions for DAEMs were used to compute the pyrolysis kinetic parameters. The energy compensation effect existed between the activation energy and the frequency factors. It can be concluded from a comprehensive F test and the amount criterion test (Akaike information criterion test) that the Weibull model is more appropriate to study the pyrolysis of rice husk. Finally, the apparent activation energy, calculated using the Weibull model, was calculated to be 131.97 kJ mol−1, whereas the reaction order was 3.2.

Pyrolysis and gasification of macroalgae Enteromorpha prolifera under a CO2 atmosphere using the thermogravimetry–Fourier transform infrared spectroscopy technique

Non-isothermal pyrolysis and gasification of Enteromorpha prolifera (also known as Ulva prolifera) under a CO2 atmosphere were investigated by thermogravimetry analysis. The gaseous products were measured online with Fourier transform infrared spectroscopy coupled with thermogravimetry. The kinetic parameters of pyrolysis and gasification reactions were obtained using the Coats–Redfern method. The experimental results showed that Enteromorpha prolifera had two derivative thermogravimetry peaks centered at 240 and 800°C, indicating the pyrolysis of organics and gasification of char, respectively. Carboxylic acids, ethers, and alcohols were the dominating condensable products generated from pyrolysis between 230 and 300°C. H2O, CH4, and aliphatic hydrocarbons were also formed in this temperature range, and they were also continuously released at higher temperatures, indicating further polymerization of the freshly generated pyrolytic char. CO was mainly produced between 700 and 900°C, and its yield was much higher than that of the pyrolytic gaseous products. The Ginstling equation (the D4 model) proved to be the most probable mechanism function for both the pyrolysis and gasification stages, with activation energies of 138.30 and 93.43 kJ mol−1, respectively.

Investigation of biochar production potential and pyrolysis kinetics characteristics of microalgal biomass

In the present work, the effect of pyrolysis conditions on biochar yield obtained from Chlorella vulgaris was examined statistically and the pyrolysis kinetics was determined using a thermogravimetric analyzer. For the production of biochar from microalgae, pyrolysis was carried out at the temperatures of 300, 500, and 700 °C, with the heating rates of 5, 15, and 25 °C/min, retention time of 0, 15, and 30 min, and nitrogen flow rate of 100 ml/min. For the examination of pyrolysis kinetic parameters, dried microalga was heated up to 900 °C at four different heating values of 5, 10, 25, and 50 °C/min at a constant nitrogen flow rate of 40 ml/min. Optimum pyrolysis conditions and the most suitable pyrolysis kinetic model were determined for Chlorella vulgaris. According to the obtained results, it was seen that Chlorella vulgaris could be easily evaluated in thermal conversion processes. Also, these results provide valuable information for optimization of biochar production, and modeling and designing of new pyrolysis systems using microalgal biomass.

A further study of pyrolysis of carbon fibre-epoxy composite from hydrogen tank: Search optimization for kinetic parameters via a Shuffled Complex Evolution.

The study of hydrogen fuel cell vehicles is currently one of the popular research topics. However, a vital issue for hydrogen fuel cell vehicles is the hydrogen tank safety when hydrogen tank catch fires. In this paper, the carbon fibre-epoxy composite from hydrogen tank was investigated by thermogravimetric analysis. Thermogravimetric experiments were carried out at three heating rates (20, 30 and 40 K/min) in a nitrogen atmosphere. A two-step parallel reaction scheme was developed for the decomposition of the carbon-fibre epoxy composite based on the K-K method and previous studies. The kinetic reaction scheme was coupled to Shuffled Complex Evolution (SCE) method to obtain optimized kinetic parameters. The predicted values using the optimized kinetic parameters show a good agreement with the experimental data, which shows the potential promising application of the reaction scheme and optimized kinetic parameters of the carbon-fibre epoxy composite.