Main Pyrolysis Stage Research Articles

Characterization and optimization of waste Cucurbita maxima moschata lashes for biomass composite applications

In this paper, 5 % sodium hydroxide solution, mixed 20 % acetic acid and 5 % sodium chlorite solution, and 5 % silane coupling agent solution were successively used to soak the waste pumpkin (Cucurbita maxima moschata) lashes. Subsequently, FTIR, XRD, thermogravimetric analysis and other experimental methods were used to comprehensively characterize the properties of the discarded pumpkin lashes. On this basis, this work prepared cement mortar specimens with unadulterated pumpkin lashes, adulterated raw pumpkin lashes, and adulterated modified pumpkin lashes, and their residual mechanical properties were investigated after exposure to elevated temperatures. The experimental results indicate that the chemical modification utilized in this paper can increase the cellulose content of pumpkin lashes as well as reduce the proportion of amorphous components, and thus, improve the tensile strength, crystallinity index, grain size, thermal stability, and surface roughness of the samples. Meanwhile, the chemical treatment process can effectively reduce the water absorption and density of pumpkin lashes. The calculation outcomes of our thermal kinetics study showed that the apparent activation energies corresponding to the main pyrolysis stage of the treated pumpkin lashes were significantly enhanced. The one-dimensional diffusion model and the second-order model could better characterize the pyrolytic mechanism of the raw pumpkin lashes, while the mechanism was closer to the third-order model because of the chemical modification. Finally, the addition of chemically modified pumpkin lashes reduced the mass loss rate of cement mortar specimens at elevated temperatures while clearly increasing the residual strength of the specimens at 300 and 400 °C compared to those with referential pumpkin lashes.

Co-pyrolysis of animal manure and plastic waste study using TG-FTIR analysis

In this paper, the co-pyrolysis of blends of animal manure (AM) and high-density polyethylene (HDPE) waste was investigated using micro-thermal analysis techniques. Thermogravimetry coupled with Fourier-transform infrared spectroscopy was used to study the process kinetics and potential synergistic effects during co-pyrolysis. Dynamic co-pyrolysis experiments of animal manure (AM) and polyethylene (PE) blends in proportions of (90:10 %) and (80:20 %) were conducted at heating rates of 5, 10, 15, and 20 °C/min under an N2 atmosphere. The process was analyzed and compared to the results obtained in the pyrolysis of pure components. AM and PE co-pyrolysis exhibited a synergic effect on the pyrolysis process, leading to a favorable change in the CPI pyrolysis initiation index. This was observed in the FTIR, shifting maximum devolatilization peaks by 14 °C towards lower temperatures and a lower activation energy of the main pyrolysis stage, with a decrease from 341.49±4.65 kJ/mol to 273.04±6.93 kJ/mol after the addition of 20 wt% PE to the blend. During co-pyrolysis, the main compounds observed in the FTIR absorption spectra were CO2, CO, CH4, NH3, and aromatic hydrocarbons from AM pyrolysis. Additionally, there was an increase in CH4 and short-chain hydrocarbons due to the PE pyrolysis.

A TGA-FTIR study on the pyrolysis of oil-based drilling cuttings and the influence of its solids on pyrolysis characteristics

During the drilling process in oil and gas fields, rock cuttings and other solid impurities are returned to the wellhead along with oil-based drilling fluids, forming oil-based drill cuttings. Organic pollutants in oil-based drill cuttings can be removed through pyrolysis. Although there has been some research on the pyrolysis of oil-based drilling cuttings, there is little analysis of the impact of rock-solid impurities in oil-based drill cuttings on the pyrolysis of organic components. Therefore, in this study, thermogravimetry coupled with infrared spectroscopy was used to analyze the pyrolysis characteristics of oil-based drill cuttings, exploring the major volatile components at different pyrolysis temperatures. Meanwhile, the oil and solids in oil-based drilling cuttings were separated by Soxhlet extraction, and the influence of solids on pyrolysis characteristics was studied. The results showed that the average pyrolysis activation energy and pre-exponential factor of the main pyrolysis stage of oil-based drill cuttings obtained by the FWO method were 50.6 KJ/mol and 3.951×104 s−1, respectively, while those of the separated residual oil were 84.7 KJ/mol and 2.905×109 s−1, respectively. This indicates that solids in oil-based drilling cuttings is increasing the mass loss rate during pyrolysis. The difference in pyrolysis kinetics between oil-based drilling cuttings and residual oil indicates that the solid in oil-based rock cuttings provides a surface for the reaction, which provides a reaction site for the decomposition of hydrocarbons to produce lighter volatile hydrocarbons. Additionally, the results of infrared spectroscopy indicated that the volatile products of the pyrolysis of oil-based drilling cuttings include CH4, CO, CO2, H2O, aldehydes, organic acids, etc. CH4 is the main product of the first weight loss stage, mainly released between 150°C and 200°C. With the increase in temperature, the concentrations of H2O, CO2, aldehydes, and organic acids gradually increased. At 600°C, the maximum concentration of CO2 release occurred, and the release of CO2 was the main reason for the third-stage weight loss in the pyrolysis of oil-based drilling cuttings

Insights into pyrolysis of ginger via TG-FTIR and Py-GC/MS analyses: Thermochemical behaviors, kinetics, evolved gas, and products

One of the key leverages for lessening the heavy reliance on fossil fuels is the conversion of non-food biomass into bioenergy and high value-added products. This study aimed to quantify the bioenergetic, emission, and biochar performances of ginger (Zb) pyrolysis. The main pyrolysis stage of Zb occurred in the range of 127–540 °C, releasing gaseous products, primarily CO2, in significant quantities between 200–600 °C. The dominant pyrolysis products were CO functional groups, accounting for 52.18–62.68% of the total. As the temperature rose, the primary pyrolysis products transitioned from ketones to benzene and its derivatives. Through the application of three model-free and three model-fitting methods, the most suitable mechanism identified for the main pyrolysis stage (0.2 < conversion degree < 0.7) was the three-dimensional diffusion (spherically symmetric) function, serving as an internal diffusion mechanism. Results of this study provide impactful and actionable insights into control over the generation of bioenergy potential, gas emissions, and value-added products via the Zb pyrolysis.

Unraveling the thermal decomposition and conversion mechanisms of silica aerogel-infused cork cells

Recently, a novel lightweight cork with enhanced thermal stability has been prepared using a respiratory impregnation method. In this paper, the thermal stability and decomposition of two kinds of cork CS-P (Quercus suber) and CV-P (Quercus variabilis B1) and corks that infused silica aerogel in cells CSS-P (Quercus suber) and CSV-P (Quercus variabilis B1) were systematically studied, and their decomposition mechanisms were proposed. The results showed that the decomposition was inhibited at 200 °C, and the pyrolysis was significantly inhibited at the main pyrolysis stage (400 °C). Interestingly, the evolved gaseous products and their evolution models have also changed. Specifically, CO2 and aldehyde emissions were significantly reduced in the main pyrolysis stage, reducing environmental pollution. Silica aerogel filler plays a catalytic role in the pyrolysis process, thus increasing the output of some value-added products (such as aromatics), which is suitable as the appropriate raw material or source of olefins to produce aliphatic rich pyrolysis biofuels. In general, the yield of biochar and bio-oil can be adjusted under low environmental pollution by loading silica aerogel and adjusting pyrolysis temperature. Corks that infused silica aerogel in cells may be a promising raw material for the production of biochar and biofuel through pyrolysis and contribute to the environmental and economic sustainability of the cork production industry.

Investigation of dust ignition sensitivity and co-pyrolysis properties of biomass and plastic waste during resource utilization

This study investigated the sensitivity of dust to ignition and the co-pyrolysis properties of biomass-plastic composites (BPCs) during resource utilization process. A model of co-pyrolysis process for four BPCs was developed using a BP neural network algorithm. The addition of polyethylene increased the biomass powder's tendency to pyrolyze. In the main pyrolysis stage, the lignin and polyethylene fractions significantly impact the synergistic effect more than the other fractions. Corn stalk/polyethylene and rice husk/polyethylene are synergistic during the pyrolysis process making these BPC products relatively promising for utilization. However, more attention should be paid to the dust explosion hazard posed by the BPCs. PE increases the ignition sensitivity of the biomass powder. Compared to other BPCs, minimum ignition temperature (420 °C) and minimum ignition energy (21 mJ) values for rice husk/polyethylene composites are the lowest. The volatile fraction of biomass content is one of the most influential factors affecting the ignition sensitivity of BPCs.

Insights into Pyrolysis Kinetics, Thermodynamics, and the Reaction Mechanism of Wheat Straw for Its Resource Utilization

To realize the energy recovery of wheat straw, the pyrolysis behavior of wheat straw was studied at three heating rates (10, 20, and 30 K/min) based on thermogravimetric analysis (TG–DTG). Kinetics and thermodynamics were analyzed using Flynn–Wall–Ozawa (FWO) and Kissinger–Akahira–Sunose (KAS) model-free methods, and the reaction mechanism was determined using the Coats–Redfern (CR) model-fitting method. The results show that there are three weightlessness stages in the pyrolysis process, of which the second stage was the main weightlessness stage and two distinct peaks of weightlessness were observed in this stage. With increasing heating rate, the main pyrolytic weightlessness peaks of the DTG curve shift to the high-temperature side. The pyrolysis activation energies calculated by the FWO and KAS methods are 165.17–440.02 kJ/mol and 163.72–452.07 kJ/mol, and the pre-exponential factors vary in the range of 2.58 × 1012–7.45 × 1036 s−1 and 1.91 × 1012–8.66 × 1037 s−1, respectively. The thermodynamic parameters indicate that wheat straw has favorable conditions for product formation and it is a promising feedstock. Its pyrolysis reaction was nonspontaneous and the energy output is stable. CR method analysis shows that the A1/3 random nucleation model is the most suitable mechanism to characterize the pyrolysis process and random nucleation may be in charge of the main pyrolysis stage. This study can provide a theoretical basis for the thermochemical conversion and utilization of wheat straw.

Thermal Decomposition Processes in Relation to the Type of Organic Matter, Mineral and Maceral Composition of Menilite Shales

The aim of the research presented in this article was to analyse the processes of source-rock decomposition, including kinetic parameters of pyrolysis, in relation to the type of the organic matter and its maturity. The examined source rocks were Menilite shales from several units within the Flysch Carpathians (Poland). The samples were analysed with use of thermal methods, including Rock-Eval and thermogravimetry coupled with an FTIR detector. Kinetic parameters were determined with use of the model-free integral isoconversion method Kissinger–Akahira–Sunose. The observed gas evolution from the source rocks indicates two stages of organic matter decomposition for some samples. The main stage of pyrolysis takes place in the temperature range from 300 to 500 °C, while the secondary—cracking—takes place in the temperature range from 500 to 650 °C. Using FTIR, we detected vibrations derived from N-H groups, which provide information on the presence of nitrogen in the organic matter, and indicate a low maturity level. C=C stretching vibrations of aromatic hydrocarbons prove a higher maturity of organic matter. The Menilite source rocks have different activation energies, which are related to different organic and mineral compositions. The maturity of organic matter does not have a decisive influence on the kinetic parameters. A high share of carbonates in the rock increases the value of the apparent activation energy. The high share of bituminite within maceral components reduces the value of activation energy.

The structural evolution characteristics for high volatile bituminous coal by in-situ heating in electronical microscope

In order to visually investigate the aromatic layer arrangement and structural evolution characteristics, high volatile bituminous coal was selected and investigated by in-situ high-resolution transmission electron microscopy (HRTEM) and thermogravimetry coupled with mass spectrometry (TG-MS). HRTEM was applied to quantify the size and arrangement of aromatic layers (such as length, curvature, orientation, d002 and Lc) during in-situ heating from room temperature (RT) to 1000 ℃, thereby revealing aromatic structural evolution characteristics. TG-MS was employed to identify gaseous release characteristics from RT to 900 ℃·H2O, CO2, CH4, C3H6, benzene and H2 were monitored and measured in this study. Based on the HRTEM experimental results, it was found that with temperature increasing, the distributions of aromatic layers changed from disordered to well-aligned and then to disordered again. Among them, the naphthalene structure, the smallest aromatic layer structure identified in the HRTEM image formed by the condensation of two benzene rings, presents the most obvious variation. In addition, the relationship between aromatic structural evolution and gaseous generation was also discussed in this work. The results showed that the structural evolution of high volatile bituminous coal was complex and closely related to the gaseous generation characteristics. At the temperature of RT∼300 ℃, the decomposing of oxygen-containing functional groups caused an increase in the content of naphthalene, the layers became shorter but more disordered, d002 decreased significantly while Lc increased. Up to 400 ℃, the layers were extended and parallel, the d002 decreased and La increased, while Lc remained almost stable, demonstrating that the polymerization of smaller layers formed in the previous stage was the main reaction in this stage. 400–600 ℃ was the main pyrolysis stage with large amounts of volatile matter generated, new active sites were thus formed and reconnected, causing the growth of aromatics and improvement of the order degree. At 600 ℃∼700 ℃, the content of naphthalene increased again, which may possibly due to the decomposition of methylene-bridge bond connected between aromatic rings, accompanied by the release of CH4 and benzene. Then the layers arrangement reached the most order and the perfect crystallite structure began to be formed gradually up to 800 ℃, which is owing to the polycondensation between the aromatics accompanied with the release of H2. As the temperature rise to 1000 ℃, the value of Lc showed a significant increase and the d002 remained a slight decrease, indicating the improving of the stacking degree, however, the formation of new naphthalene through the aromatization of aliphatic rings caused the naphthalene content increase and La reduce significantly.

Comparative Study on Pyrolysis Kinetics Behavior and High-Temperature Fast Pyrolysis Product Analysis of Coastal Zone and Land Biomasses.

The pyrolysis characteristics of land biomass (corn stalks (Cs), pine sawdust (Ps)) and coastal zone biomass (Jerusalem artichoke stalks (JAs) and reed (Re)) were investigated based on thermogravimetric analysis (TGA) and products’ analysis. The kinetic parameters were obtained by three isoconversional methods (Friedman, KAS, and FWO) and one model-fitting method (DAEM). The simultaneous effect of high temperature (700–900 °C) and high heating rate (1000 °C/s) on the pyrolysis product simulating the typical conditions of a fluidized bed gasifier was studied. TGA showed that high heating rates deepen the thermal cracking process of biomass. Compared with the land biomass, the initial decomposition temperature (Ti) of the coastal biomass is reduced significantly owing to its higher proportion of hemicellulose. These methods agree with the trends shown by the activation energy (Ea) distribution calculated, with fluctuations between 160 and 350 kJ/mol. The mean value activation energies of Re and JAs were higher than those of Cs and Ps between 10% and 90% conversion. The DAEM model showed that Cs and JAs have a good linear relationship between ln A and Eα during the main pyrolysis stage, while Ps and Re are relatively weaker. The kinetic compensation effect was evident for Cs and JAs during the main thermal cracking stage. Py-GC-MS results confirmed that phenols, hydrocarbons, PAHs, and oxygen heterocycle compounds were strongly present in the released volatile products. High-temperature fast pyrolysis of JAs produced a larger amount of PAH compounds than from Cs, Ps, and Re. A larger amount of hydrocarbons and phenols was generated from high-temperature fast pyrolysis of Ps. Some oxygen-containing volatiles are easily converted into aromatic products with higher stability under high temperature.

Study on the Differences of Chemical Structures and Pyrolysis Characteristics between the Jurassic and Carboniferous Coking Coals.

Using Jurassic coking coals and Carboniferous coking coals as raw materials, carbonization experiments were carried out on the cokes produced by them in a self-made furnace in a laboratory-scale coking furnace, finding that the coke quality of the Jurassic fat coals and coking coals was obviously inferior to that of the Carboniferous coking coals of the same brand. In this study, the reasons for this phenomenon were studied by elemental analysis, Fourier transform infrared spectroscopy analysis, and thermogravimetric analysis of experimental coal samples and by combining the differences in chemical structures of experimental coal samples with pyrolysis characteristic parameters. It was found that the key factor affecting the quality of cokes made from the Jurassic fat coals, coking coals, and highly volatile coking coals was that the coals contained too many oxygen-containing functional groups, which were decomposed into reactive oxygen species in the main pyrolysis stage of coal. These reactive oxygen species would consume too much free-moving hydrogen and then trigger a large number of condensation and cross-linking reactions, resulting in poor plastic mass and coke quality.

Thermal and kinetic analyzing of pyrolysis and combustion of self-heating biomass particles

As a renewable fuel, the application of biomass fuel gets more and more attention. Fire and explosion are the main safety problems in the biomass fuel storage process. The characteristic parameters and kinetic analysis of pyrolysis and combustion are significant to guide the safe storage of biomass fuel. In this work, the thermogravimetric analysis (TGA) was used to obtain the pyrolysis and combustion characteristics of corn straw powder, poplar wood chip and rice husk in nitrogen and air, respectively. The Thermogravimetry-Differential Thermogravimetric (TG-DTG) profile shows that the pyrolysis process of these biomass includes three stages of drying, pyrolysis and carbonization, while the combustion process includes three stages of drying, devolatilization and coke combustion. The main reaction stage of biomass pyrolysis and combustion are roughly between 170∼400 °C and 180∼530 °C, respectively. With the increase of the heating rate, TG and DTG profiles shifts to the high temperature side. Furthermore, the kinetic analysis was performed by using Kissinger-Akahira-Sunose (KAS), Flynn-Wall-Ozawa (FWO), Friedman, and Coats-Redfern (CR) methods, based on the thermogravimetric experimental data. The activation energy of biomass pyrolysis is shown to be between 70∼100 kJ/mol. For the activation energy of biomass combustion, the calculated value from isoconversional methods is between 140∼180 kJ/mol. The calculated value from CR method is between 80∼150 kJ/mol, and the activation energy of the coke combustion stage is greater than that of the devolatilization stage. Finally, the auto-ignition experiment of biomass particles was designed and conducted, indicating that the corn straw powder is more prone to spontaneous combustion, followed by rice husk and poplar wood chip, which corresponds to the results of activation energy. And the fire hazard of the biomass particles was analyzed according to the characteristic parameters. This work provides fundamental data to promote the development of storage techniques and facilitate the safe production of biomass particles.

Thermodynamic mechanism evaluate the feasibility of oil shale pyrolysis by topochemical heat

Topochemical heat in-situ pyrolysis of oil shale is achieved by injecting high temperature nitrogen to promote oil shale pyrolysis and release heat, and then injecting air to trigger oil shale combustion in the early stage of oil shale pyrolysis, and then by injecting normal temperature air continuously to promote local oxidation of oil shale in the later stage. In order to verify the oil and gas recovery by topochemical heat method, Jilin University has chosen Fuyu City, Jilin Province, to carry out pilot project of oil shale in-situ pyrolysis by topochemical heat method. Besides, in order to infer the spontaneity, feasibility and difficulty of continuous pyrolysis of oil shale based on topochemical heat, this paper, the mechanism of solid-state pyrolysis and the thermodynamic analysis of transition state of oil shale in Fuyu area are discussed. Because the second stage of oil shale pyrolysis is the main stage of oil production. Therefore, the characteristics of Gibbs free energy, free enthalpy and free entropy of transition state in the main oil production stage of oil shale pyrolysis are obtained by calculation. The results show that in situ pyrolysis of oil shale topochemical heat can be carried out spontaneously and continuously, and the release characteristics of volatiles during pyrolysis of oil shale are described.

Effect of potassium on the pyrolysis of biomass components: Pyrolysis behaviors, product distribution and kinetic characteristics

Potassium is an inorganic mineral element in biomass and has a significant catalytic effect on biomass pyrolysis. In this work, the effect of potassium on the pyrolysis of biomass components (cellulose, xylan and lignin) was investigated with the help of thermogravimetric analyzer coupled to fourier transform infrared spectrometer (TG-FTIR) and pyrolysis–gas chromatography coupled to mass spectrometry (Py-GC/MS). The results showed that potassium accelerated the start of the main pyrolysis stage of the biomass components, reduced the weight loss rate for cellulose and lignin, and increased the weight loss rate for xylan. On the other hand, potassium presented a promotion effect on the formation of char for cellulose but a suppression effect for lignin. In addition, an increasing potassium content promoted the release of volatile products for xylan. Product distribution analysis found that potassium promoted the scission of glycosidic bonds and the decomposition of glucose units, resulting in a sharp yield decrease of carbohydrates and a yield increase of furans, aldehydes and ketones. In addition, an increased production of CO2 was obtained, indicating that potassium favors the cleavage and reforming of carboxyl (COOH) and carbonyl (CO) groups. Furthermore, the effect of potassium on the pyrolysis of cellulose and xylan was stronger than that on lignin pyrolysis. The effect on the pyrolysis reaction also resulted in a higher activation energy for the decomposition of biomass components, especially at high temperature intervals. Moreover, the higher the content of potassium added, the greater the increase was in the activation energy.

Microwave-assisted catalytic pyrolysis of apple wood to produce biochar: Co-pyrolysis behavior, pyrolysis kinetics analysis and evaluation of microbial carriers

This studyinvestigated the behavior and kinetics of co-pyrolysis of apple wood (AW)with H3PO4and K3PO4as catalysts under microwaveto prepare biochar as microbialabsorbent. The kinetic studies indicate that the co-pyrolysis of AW withH3PO4orK3PO4can effectively improve the pyrolysis efficiencyand enhance the biocharcharacteristicsby reducing ofthe activation energy of the pyrolysis reaction. The kinetic parameters indicate that the activation energy of the mixturesin the main pyrolysis stage is lower than that of a single AW, whichmeanthat the co-pyrolysis of AW withH3PO4orK3PO4shows excellent synergy. Biochar characterization showed that the yield of biochar reachedthe highest58.6% whenthe ratio(H3PO4/AW) is0.5. The adsorption results show that the bacteria SL-44 can be effectively loaded on the surface of the biochar, and the adsorption process is combined with Langmuir model and process can proceed spontaneously.

Thermal decomposed behavior and kinetic study for untreated and flame retardant treated regenerated cellulose fibers using thermogravimetric analysis

In the present work, pyrolysis kinetic mechanism was studied for regenerated cellulosic fiber (RCF) and composite RCF containing silicon/nitrogen flame retardants. Limited oxygen index and microscale combustion calorimeter tests show that the loading of nitrogen/silicon into the RCF enhanced flame retardancy. The kinetic triplets of the two kinds of samples were determined by applying iso-conversional methods and integral master plots approach. Compared to the untreated RCF, flame retardant (FR) treated RCF shows enhanced activation energy due to the physical barrier layer due to dehydration of silicate and charring effect resulting from organic–inorganic interaction. Exponential nucleation model can be successful in describing experimental results for RCF in higher conversion degree (0.4–0.9). Simultaneously, the degradation process of FR treated RCF in the main pyrolysis stage (0.2–0.7) is consistent with kinetics of nuclei growth and could be described by one-step reaction whose rate presented an Avrami–Erofeev-type model (n = 2.38).

Kinetic Analysis of the Thermal Decomposition of Lowland and High-Moor Peats

The thermal decomposition of two types of peat from the Vladimir oblast of Russia in an inert atmosphere of argon was studied for the first time with the combined use of thermogravimetry, Fourier transform IR spectroscopy, and kinetic analysis. The majority of gaseous products (CO2, CO, and CH4) were released at the main stage of pyrolysis at a decomposition temperature of 150–540°C, which was accompanied by the greatest weight loss. As a result of thermal decomposition, the predominant portion of the organic matter of peat passed into a gas phase. The Ozava–Flynn–Wall integral isoconversion method and the Criado method were used to calculate the kinetic parameters of the thermal decomposition of peat and to determine the mechanism of decomposition, respectively. The activation energies of peat varied in a range of 54–271 kJ/mol, and heat transfer occurred through three-dimensional diffusion.

Effects of apparent activation energy in pyrolytic carbonization on the synthesis of MOFs-carbon involving thermal analysis kinetics and decomposition mechanism

Pyrolysis process of metal-organic frameworks (MOFs) was analyzed by thermal analysis kinetics for the study of the synthesis of MOFs-based carbon materials with high adsorption performance. The process was studied based on the thermogravimetric mass spectrometry (TG-MS), through which the gas products of the pyrolysis process were detected. The HKUST-1 and MIL-101 were prepared by solvothermal method and characterized by XRD, BET, SEM and TEM. The characterization results showed that HKUST-1 and MIL-101 have been successfully prepared with cubic octahedral morphology and specific surface areas up to 1477.50 m2/g and 2239.88 m2/g, respectively. The data of TG-DTG showed that the pyrolysis of HKUST-1 and MIL-101 could be divided into three stages and seven stages, respectively. The kinetic triplets of different pyrolysis stages were calculated by iso-conversional methods, and the gas products decomposed were analyzed, through which the pyrolysis mechanism of MOFs was inferred. The first pyrolysis stages of HKUST-1 and MIL-101 were both dehydration stages, the E values of both were less than 100 kJ/mol, and the pyrolysis mechanism of both two materials at this stage were the chemical reaction mechanism. The average apparent activation energy of the main pyrolysis carbonization stages of both was about 180 kJ/mol, and both followed the random nucleation and subsequent growth mechanism, indicating that there were some uniformities between the two materials in the main pyrolysis stage. The main gas products in this stage were CO, CO2 and benzene. The apparent activation energy of the final deep carbonization stage were 564.36 and 387.60 kJ/mol, respectively, and mechanisms followed were chemical reactions and three-dimensional diffusion mechanisms, meaning that there were some differences between the two materials in the deepening stage.

Thermogravimetric Analysis and Pyrolysis Kinetics of Tannery Wastes in an Inert Atmosphere

Industrial wastes generated from tanneries contain large quantities of water-insoluble proteins, which may be used for the production of composite materials, renewable chemicals and energy. In this work, the pyrolysis kinetics of powdered sheep fur wastes (SFW) was studied by thermogravimetry (TG) at different heating rates from room temperature to 600°C in nitrogen atmosphere. TG results revealed that there are three stages in this process. The overall apparent activation energy (E) in the main pyrolysis stage was determined to be 275.6 kJ mol-1 by modified Kissinger-Akahira-Sunose (MKAS) method. Because the pyrolysis of SFW could not be described by a single-step reaction, the experimental DTG curve of SFW was deconvoluted into three individual peaks followed by reconstruction of TG curves corresponding to three pseudo components. The average values of E obtained for these pseudo components are 234.7 kJ mol-1, 176.4 kJ mol-1, and 186.2 kJ mol-1, respectively. Generalized master-plots method indicated that the SFW pyrolysis may follow the random nucleation and growth mechanism (Avrami-Erofeev model). Reaction model functions f(?) for these pseudo components could be expressed as: f(?)=3.1(1-?)[-ln(1-?)]0.67; f(?)=3.6(1-?)[-ln(1-?)]0.72, and f(?)=3.9(1-?)[-ln(1-?)]0.74, respectively. These results may provide insight for further studies as well as for future application of pyrolysis technology for tannery wastes.

Comparative study on pyrolysis characteristics and kinetics of oleaginous yeast and algae

The pyrolysis processes of oleaginous yeast and algae were studied and compared using a non-isothermal thermogravimetric analyzer at heating rates of 10–50 °C/min, and the most probable mechanism function and kinetic analyses of the main stage of pyrolysis were carried out by the Popuse method, Starink method, and Fridemen method. The main pyrolysis stage of the samples could be described by the Jander equation and Z–L–T equation and the activation energy of the three biomass was 108–117, 107–121 and 93–108 kJ/mol, respectively. For the three kinds of biomass, the DTG curves were divided based on the four pseudo-components by performing Gaussian fitting which are carbohydrates, proteins, lipids, others, and the weight coefficients of them could be identified. The activation energy of each pseudo-component was obtained in the range of 58.36–140.44 kJ/mol by the Kissinger method. The four-pseudo-component model based on Gaussian fitting provides effective data for the design of oleaginous yeast and algae thermal decomposition systems and the kinetic analysis of the pyrolysis process.