Kissinger Akahira Sunose Research Articles

Influence of Intrinsic Physicochemical Properties of Agroforestry Waste on Its Pyrolysis Characteristics and Behavior.

To obtain a comprehensive understanding of the qualitative and quantitative effects of the intrinsic properties of biomass on its pyrolysis characteristics and assess the behavior of agroforestry waste, thermogravimetric analyses of three representative agroforestry wastes, namely rape (Brassica campestris L.) straw (RS), apple (Malus domestica) tree branches (ATB), and pine (Pinus sp.) sawdust (PS), were carried out by pyrolysis under dynamic conditions (30 to 900 °C) at different heating rates of 5, 10, and 15 °C·min-1. Correlation analysis showed that intrinsic physicochemical properties play distinct roles in different stages of pyrolysis. The ash content was negatively correlated with the temperature range (R2) of the second stage (190-380 °C) of pyrolysis. The lignin content and the amount of pyrolysis residues (RSS) were positively correlated. Kinetic triplets, including the activation energy (Ea), pre-exponential factor (A), and reaction model [f(α)], were obtained using different methods, including the Flynn-Wall-Ozawa (FWO), Freidman, Kissinger-Akahira-Sunose (KAS), and Starink methods. The mean activation energy (Ea[mean]) for RS, ATB, and PS calculated by the different methods ranged from 167.15 to 195.58 kJ·mol-1, 195.37 to 234.95 kJ·mol-1, and 191.27-236.45 kJ·mol-1, respectively. Correlation analysis of the intrinsic physicochemical characteristics and kinetic factors of agroforestry waste showed that the minimum Ea (Ea[min]) was significantly positively correlated with heat capacity (C0) and negatively correlated with thermal diffusivity (D). The Ea[mean] and the maximum value of Ea (Ea[max]) significantly positively correlated with the sum content of cellulose and lignin, indicating that the contents of cellulose and lignin determines the energy required for the pyrolysis process of agroforestry waste. The mechanism of degradation involves the diffusion model (D1, D2, and D3), the growth model (A4), and the geometrical contraction model (R3). These results indicate that the pyrolysis of agroforestry waste is a complex process due to the heterogeneity of its intrinsic physicochemical properties.

Catalytic Pyrolysis of PET Polymer Using Nonisothermal Thermogravimetric Analysis Data: Kinetics and Artificial Neural Networks Studies.

This paper presents the catalytic pyrolysis of a constant-composition mixture of zeolite β and polyethylene terephthalate (PET) polymer by thermogravimetric analysis (TGA) at different heating rates (2, 5, 10, and 20 K/min). The thermograms showed only one main reaction and shifted to higher temperatures with increasing heating rate. In addition, at constant heating rate, they moved to lower temperatures of pure PET pyrolysis when a catalyst was added. Four isoconversional models, namely, Kissinger−Akahira−Sunose (KAS), Friedman, Flynn−Wall−Qzawa (FWO), and Starink, were applied to obtain the activation energy (Ea). Values of Ea acquired by these models were very close to each other with average value of Ea = 154.0 kJ/mol, which was much lower than that for pure PET pyrolysis. The Coats−Redfern and Criado methods were employed to set the most convenient solid-state reaction mechanism. These methods revealed that the experimental data matched those obtained by different mechanisms depending on the heating rate. Values of Ea obtained by these two models were within the average values of 157 kJ/mol. An artificial neural network (ANN) was utilized to predict the remaining weight fraction using two input variables (temperature and heating rate). The results proved that ANN could predict the experimental value very efficiently (R2 > 0.999) even with new data.

Pyrolysis Kinetic Study of Polylactic Acid

Polylactic acid (PLA) is a biodegradable polymer and is mainly used in the textile and food packaging fields. The aim of this work is to build knowledge on the kinetics of the pyrolysis of PLA with the help of thermogravimetric analysis (TGA) using four model-free methods, namely Friedman, Flynn-Wall-Qzawa (FWO), Kissinger-Akahira-Sunose (KAS), and Starink. Additionally, two model-fitting methods (the Coats-Redfern and Criado methods) were applied. TGA data at 5, 10, 20, and 30 K/min heating rates were collected. The obtained activation energies of the pyrolysis of PLA at different conversions by the model-free models were in good agreement and the average values were 97, 109, 104, and 104 kJ/mol for Friedman, FWO, KAS, and Starink, respectively. The Criado model was used together with the Coats-Redfern model to identify the most appropriate reaction mechanism. As per this work, the best controlling reaction mechanism of the PLA pyrolysis can be expressed by the geometrical contraction model (R2).

Impact of temperature severity on hydrothermal carbonization: Fuel properties, kinetic and thermodynamic parameters

The current study intended to explore the impact of hydrothermal carbonization temperature (180, 230, and 280 °C) on the fuel properties, kinetics, thermodynamics, and reaction mechanism of sunflower stalks (SS). Hydrochars obtained at different temperatures were pyrolyzed in a TGA (Thermogravimetric analyzer) at three distinct heating rates. The impact on functional groups, surface morphology, and crystallinity were examined based on the characterization methods such as FTIR, FE-SEM, and XRD. The kinetic parameters were estimated based on the isoconversional methods of Kissinger Akahira Sunose (KAS), Ozawa Flynn Wall (OFW), and Vyazovkin (VZK), whereas the reaction mechanism was deduced employing Z(α) master plot method. The mean value of activation energy obtained for the raw-SS, SS-180, SS-230, and SS-280 was (188.71, 189.06, and 176.4 kJ/mol), (165.6, 167.33, and 155.54 kJ/mol), (219.77, 218.78, and 206.83 kJ/mol), and (299.37, 296.6, and 281.02 kJ/mol) based on KAS, OFW, and VZK method, respectively. The findings of the current study can be used to develop and design pyrolysis reactors for clean biofuel generation from SS.

Production of Biodiesel by Transesterification of Pilot Plant Waste over Nickel (Ni)/Eggshell (CaO) Catalyst

The increment of pilot plant waste at UniKL MICET and eggshell waste cause disposal problems, such as the water and soil pollution, human health concerns, and disruption to aquatic ecosystems. Thus, to reduce the effect of disposal problem to the environment, pilot plant waste is converted into biodiesel, while eggshell is converted into catalyst in this study. This paper reports on the effect of catalyst preparation method and reaction temperature on biodiesel yield and quality. Transesterification process of pilot plant waste (olein and stearin) was conducted by using Ni/CaO (eggshell) catalyst from different preparation methods at different reaction temperatures (328 K, 333 K, 338 K and constant reaction time (5 hours), methanol-to-oil ratio (15:1), and weight of catalyst (8 wt%). The catalysts were synthesized via wet impregnation and sol–gel method and its physicochemical properties were subsequently characterized by TGA and FTIR analysis. Biodiesel analysis was done using GCMS and FTIR, while the physical properties (density, flash point, and kinematic viscosity) of biodiesel were measured according to ASTM D6751. Kissinger-Akahira-Sunose (KAS) kinetic model shows that the catalyst prepared by wet impregnation method has the lowest activation energy, which was 81.48 kJ mol–1. In addition, GCMS analysis shows that reaction temperature at 338 K produced the highest yield of biodiesel (88.26%). In conclusion, the best catalyst preparation method was wet impregnation method and the best reaction temperature was 338 K. In addition, the physical properties of the produced biodiesel corresponded to ASTM standard, thereby indicating high quality of biodiesel and can be used as petroleum-diesel substitute.

Decomposition behavior and kinetics of Beydili and Ihsangazi oil shale deposits (Turkiye) by TG-DTG-MS

This research mainly investigates the decomposition behavior and kinetics of Beydili and Ihsangazi oil shale deposits (Türkiye) by TG-DTG and MS techniques. In the initial stage of the research, geochemical and organic characterization (total organic carbon, rock-eval, fisher assay, x-ray fluorescence, etc.) of the oil shale samples were determined. TG-DTG-MS analyses of the oil shale samples were performed at three different heating rates in an air atmosphere. In all the oil shale samples studied, the TG-DTG curves indicated that the decomposition of oil shale samples followed two successive reaction stages in different temperature intervals, known as pyrolysis and mineral decomposition. In these two stages, reaction intervals, peak temperature, mass loss, derivative mass loss rate values, and gaseous constituent (MS analysis) of oil shale samples are all determined. At the same time, the different combustibility indices, such as the ignition index, combustion index, and reactivity of oil shale samples, are also determined. Also, for each reaction region, activation energy values were calculated using two different model-free methods known as Kissinger - Akahira – Sunose (KAS) and Ozawa - Flynn – Wall (OFW). In pyrolysis and mineral decomposition regions, the activation energy values varied between 73.9 and 186.4 kJ/mol and 103.3–297.1 kJ/mol.

Valorization of the biomass of Rhizoclonium hookeri through slow pyrolysis and its thermokinetic investigation for bioenergy potential

The macroalgae, Rhizoclonium hookeri has the ability to grow in fresh and wastewater rich in nutrients like phosphorus and nitrogen. Here we have performed the slow pyrolysis of dried R. hookeri at three different thermal rates of 5, 10 and 20 °C min−1 from 25 to 800 °C using the thermogravimetric technique to get the thermokinetics for its bioenergy value. Four different thermal degradation stages were considered to get the kinetic triplets from its pyrolysis. The activation energy was obtained for each stage of thermal decomposition utilizing four classical isoconversional methods (Friedman, Flynn–Wall–Ozawa, Kissinger–Akahira–Sunose, and Starink). The activation energies obtained through these isoconversional methods for the four valorization zones of R. hookeri were in the range of 151.15–192.62 kJ mol−1. The pre-exponential factor (A) showing the chemical nature of each reaction step was extracted from the kinetic compensation effect and has values in the range of 1.99 × 1020 to 2.63 × 1012 min−1. The thermodynamic parameters revealed the non-spontaneous, endothermic and complex nature of the pyrolysis process of Rhizoclonium biomass. The thermokinetic data showed that Rhizoclonium biomass has bioenergy potential like other macroalgae and is a suitable feedstock for the large-scale pyrolysis process. In conclusion, the outcomes from this study suggest the suitability of Rhizoclonium hookeri as a feedstock for producing bioenergy and is of great significance for designing large-scale equipment to pyrolyze this macroalgal specie.

Co-combustion of municipal solid waste and hydrochars under non-isothermal conditions: Thermal behaviors, gaseous emissions and kinetic analyses by TGA–FTIR

Co-combustion of municipal solid waste (MSW) with hydrochars was proposed as an effective way for both simultaneous treatments of MSW with biomass and energy recovery. In this work, thermogravimetric analyzer coupled with Fourier transform infrared spectrometer was employed to study the (co-)combustion, gaseous emissions and combustion kinetics characteristics of MSW, hydrochars and their blends. The addition of hydrochars to MSW leads to lower burnout temperatures and the shorter combustion time. Hydrochar prepared at 200 °C (SD200) has a better co-combustion performance than hydrochars prepared at 230 (SD230) and 260 °C (SD260) in term of ignition, burnout and comprehensive combustion characteristic index, hydrochar prepared at 260 °C has a better co-combustion evenness. The addition of hydrochar to MSW changed the gaseous products emission patterns of MSW and reduced the release of CO, HCN, NO and HCl. Kissinger-Akahira-Sunose (KAS) and Flynn–Wall–Ozawa (FWO) methods were used to estimate the activation energy of MSW, SD200 and their blends, the minimum average activation energy was observed when the SD200 blending ratio was 70%, which was 75.65 kJ mol−1 by KAS and 82.12 kJ mol−1 by FWO, respectively.

Pyrolytic kinetics, reaction mechanisms and gas emissions of waste automotive paint sludge via TG-FTIR and Py-GC/MS

The present study experimentally quantified the pyrolysis behaviors of waste solvent-based automotive paint sludge (OAPS) and water-based automotive paint sludge (WAPS) at four different heating rates using thermogravimetric-Fourier transform infrared (TG-FTIR) spectrometry and pyrolysis-gas chromatography-mass (Py-GC/MS) spectrometry analyses. Flynn-Wall-Ozawa (FWO) and Kissinger-Akahira-Sunose (KAS) methods combined with the master-plots method were employed to investigate the pyrolysis kinetics and reaction mechanisms of waste automotive paint sludge. Three reaction stages and three reaction peaks in stage 2 were distinguished for both OAPS and WAPS degradation. The average activation energy (Ea) estimates for OAPS (FWO: 179.09 kJ/mol; KAS: 168.28 kJ/mol) were slightly higher than WAPS (FWO: 175.90 kJ/mol; KAS: 164.80 kJ/mol) according to FWO and KAS methods. The main pyrolysis reaction mechanisms of both OAPS and WAPS closely matched with the order-based model corresponding to 3rd and 2nd order random nucleation on an individual particle. The evolved gas species of CH4, CO2, phenols, NH3, H2O, and CO from OAPS and WAPS pyrolysis were identified by TG-FTIR. According to Py-GC/MS, hydrocarbons (47.2%) and O-components (42.7%) were relatively large after OAPS and WAPS pyrolysis, respectively. Melamine was the most abundant N-component product after pyrolysis of OAPS (5.8%) and WAPS (4.8%).

Curing kinetics and mechanical properties of an underwater SiO2/epoxy adhesive

ABSTRACT In this study, an SiO2/epoxy adhesive that can be cured in a wet/water environment was prepared. Nonisothermal differential scanning calorimetry was used to evaluate the curing reaction of this adhesive. Kinetic parameters of the adhesive were obtained using the Kissinger, Ozawa, Flynn–Wall–Ozawa, and Kissinger–Akahira–Sunose methods. The results show that the isoconversional methods can well explain the curing behavior of SiO2/epoxy adhesive. Further, the tensile lap-shear strength of the prepared adhesive cured in air and water increased by 35.96% and 32.07% than pure epoxy adhesive, respectively. Although the presence of water molecules affects the bond strength of the SiO2/epoxy adhesive, its bond strength underwater was only 1.45 MPa lower than that in air. Compared to the pure epoxy resin, the tensile and flexural strength of SiO2/epoxy adhesive cured in air were 12.23%, 6.67% higher and those of the adhesive cured in water were 10.24% and 6.62% higher, respectively. Compared to the pure epoxy resin, the tensile and flexural modulus of SiO2/epoxy adhesive cured in air increased by 13.71%, 10.25% and those of the adhesive cured in water increased by 11.21% and 10.41%, respectively.

Co-pyrolysis of waste polyester enameled wires and polyvinyl chloride: Evolved products and pyrolysis mechanism analysis

Waste enameled copper wire is an important secondary source of copper and often recovered by removing their organic paint layer through pyrolysis. This research focused on studying co-pyrolysis behaviors of poly(ethylene terephthalate) (PET) paint of waste enameled wires, mixed with a small amount of polyvinyl chloride (PVC) which is part of electric wires or cables. The results indicated that mixing PVC with a mass fraction of 10% into enameled PET wire paint (EPET) would significantly affect pyrolysis products, especially the chlorinated compounds, as well as increase energy consumption of the pyrolysis process. TG-FTIR and Py-GC/MS analyses showed that the chlorinated organics were mainly generated in the second stage of pyrolysis. Chloroesters such as terephthalic acid, di(2-chloroethyl) ester were dominant over other chloroorganic compounds, and their formations were attributed to the addition reaction of aromatic vinyl esters with HCl which formed from PVC pyrolysis. It is also worth mentioning that the chemically active acid chlorides including propanoyl chloride and benzoyl chloride were detected in the products, and they were proposed to be formed from the HCl acidolysis of esters that produced from pyrolytic EPET. Besides pyrolysis products, energy consumption of pyrolysis process also was closely correlated to the interactions between pyrolytic PVC and EPET. The average co-pyrolysis activation energy was calculated by Kissinger-Akahira-Sunose (KAS) method and was about 15 kJ/mol higher than that of EPET. These should be consequences of reactions between HCl and EPET. Since PVC is the minority component in the pyrolysis mixture that HCl eliminated from the few PVC was mostly consumed by EPET to form chloroorganic compounds, which negatively influences EPET degradation.

Thermal degradation and thermal kinetic of SEBS block copolymer compatibilized PS/HDPE blends

The effect of styrene-ethylene/butylene-styrene block copolymer (SEBS) on the thermal degradation of polystyrene (PS)/high density polyethylene (HDPE) blends have been investigated. Polystyrene and (HDPE) are widely used thermoplastics, which have extensive application in everyday life. The main disadvantage of PS/PE systems is their poor miscibility which can be improved by adding compatibilizer. The blends were prepared by melt mixing in a twin screw extruder Haake Record 90. The behavior of the thermal degradation of PS/HDPE and PS/HDPE/SEBS blends has been investigated in inert nitrogen atmosphere by using thermogravimetric analysis (TGA) to obtain the degradation temperature and activation energy ( E a). The Ea for the PS/HDPE blends as well as for the PS/HDPE/SEBS blends was determined by the isoconversional Kissinger–Akahira–Sunose (KAS) method. The results indicated that the HDPE enhance thermal properties of the blends. The addition of SEBS in PS/HDPE blends increased the E a in all blends.

Investigation of combustion performance of tannery sewage sludge using thermokinetic analysis and prediction by artificial neural network

The disposal and the management of sewage sludge from tanneries is a challenging issue for the leather industries because of their adverse effect on the environment. In this study the detailed characterization and assessment using kinetic and thermodynamic parameters of the tannery sewage sludge in combustion environment was employed. Isoconversional model-free methods like Ozawa-Flynn-Wall (OFW), Friedman and Kissinger-Akahira-Sunose (KAS) were employed to investigate the kinetics and the thermodynamic parameters in the air environment. Activation energies (Ea) for the Friedman, KAS and OFW were reported. The DTG curves at the heating rate of 5, 10, 20 and 40 °C/min show the diversified conversions in three major stages. The Ea values for the model ranges are Friedman (148.96 kJ/mol-395.23 kJ/mol), KAS (169.65 kJ/mol-383.75 kJ/mol) and OFW (176.44 kJ/mol-377.85 kJ/mol). The average Ea for the Friedman is 226.04 kJ/mol while for KAS and OFW the average Ea is 230.71 kJ/mol and 230.11 kJ/mol. Moreover, the values of ΔH, ΔG, and ΔS were analysed. Furthermore, the frequency distribution by applying the DAEM model is investigated, and there are six pseudo-components involved in the frequency distribution for combustion. For the thermal degradation prediction of the sewage sludge from the tannery, an artificial neural network (ANN) of the MLP-3-7-1 model was used. This model shows that there is good agreement between the experimental and the predicted values. Overall, this study highlights the importance of the ANN for the prediction of combustion behaviour of biomass with more accuracy.

Effect of particle size on the kinetics of pure oxygen combustion of coke

Non-isothermal thermogravimetry technique was used to analyze three groups of coke samples (S-ZD, M-ZD, and L-ZD) of varying particle sizes. The effect of particle size on kinetic parameters was studied in a pure oxygen atmosphere. The ignition (Ti), peak (Tp), and burnout (Tf) temperatures and the flammability (C) and combustion characteristic (Sn) indexes were determined by varying the heating rate (β). The activation energy (Eα) was evaluated following the Flynn–Wall–Ozawa (FWO) and Kissinger–Akahira–Sunose (KAS) methods. Ti, Tp, Tf, C, and Sn correlated positively with the increase in β in a pure oxygen atmosphere. The order of ignition was L-ZD > M-ZD > S-ZD, and the Eα values for the S-ZD, M-ZD, and L-ZD samples were 98.49, 98.35, and 95.17 kJ·mol−1 (FWO) and 90.32, 90.92, and 89.25 kJ·mol−1 (KAS), respectively. Particle size exerted little effect on the kinetics of coke combustion.

Mechanisms of the Ammonium Sulfate Roasting of Spent Lithium-Ion Batteries.

Ammonium sulfate ((NH4)2SO4) assisted roasting has been proven to be an effective way to convert spent lithium-ion battery cathodes to water-soluble salts. Herein, thermogravimetric (TG) experiments are performed to analyze the mechanism of the sulfation conversion process. First, the reaction activation energies of the sulfate-assisted roasting are 88.87 and 95.27kJ mol-1, which are calculated by Kissinger-Akahira-Sunose (KAS) and Flynn-Wall-Ozawa (FWO) methods, respectively. Then, nucleation and growth are determined and verified as the sulfation reaction model by the Šatava-Šesták method. Finally, sub-reactions of the sulfation process are investigated and reaction controlling mechanisms are determined by the contribution of sub-reaction. Based on the thermogravimetric analysis, the phase boundary reaction is found to dominate in the initial step of the roasting process (α< 0.6) while the nucleation reaction controlls the following step (α> 0.6), agreeing well with changing trend of activation energy. Overall, thermogravimetric analysis is a general way to study the mechanism of the various roasting processes.

Thermal and electrical transport property study of direct vapour transport grown Cu2SnS3 single crystals

Copper tin sulphide (Cu2SnS3) (CTS) single crystals are grown by vapour transport technique of direct (DVT) type. The stoichiometric compositional analysis; Cu: 40.78 % (37.21 %), Sn: 31.09 % (34.35 %) and S: 28.13 % (28.15 %); showed the crystals to be slightly copper rich and tin deficient, bracket values are standard data. The X-ray diffraction showed the CTS to possess cubic unit structure having lattice parameter of 5.43 Å. The high resolution transmission electron microscopy substantiated the crystalline character. The thermal analysis are carried out by recording simultaneous thermogravimetric, differential thermogravimetric and differential thermal analysis curves. These analysis are done in inert atmosphere for three heating rates of 10, 15 and 20 K⋅min−1 in the range from ambient to 1023 K. The thermocurves are analyzed by two standard methods of Kissinger-Akahira-Sunose (KAS) and Flynn-Wall-Ozawa (FWO). The thermodynamic parameters like activation energy, changes of entropy, enthalphy and Gibbs free energy are determined using KAS and FWO methods. These determined thermodynamic parameters of as-grown CTS single crystals matches each other stating the validity of the analysis. Temperature variation of electrical transport properties like dc electrical resistivity (ρ) and Seebeck coefficient (S) are measured in the temperature range of 323 K to 473 K. The values of ‘ρ’ decreases with temperature, stating semiconducting nature of crystals. The observed ‘S’ values are found to be positive in entire temperature range, stating crystals to be of p-type semiconducting nature.

Effect of oxygen on thermal behaviors and kinetic characteristics of biomass during slow and flash pyrolysis processes

Pyrolysis is usually considered as the initial stage of solid fuel combustion and gasification, and the pyrolysis characteristics in oxidizing atmosphere greatly affect the ignition behavior, flame stability and product distribution. However, the effect of oxygen on thermal behaviors and kinetic characteristics of biomass pyrolysis was poorly understood and has been studied only based on thermogravimetric analysis (TGA). TGA has heat transfer limitations, resulting in a significant difference between the calculated kinetic results and actual ones. In this work, a bubbling fluidized bed with an on-line analysis system was developed to investigate the real-time gas releasing behaviors of biomass flash pyrolysis in inert and oxidizing atmospheres. The slow pyrolysis characteristics were investigated in TGA for comparison. The effects of oxygen on the kinetics of flash and slow pyrolysis were investigated by combining the distributed activation energy model (DAEM) isothermal model and non-isothermal models including Flynn-Wall-Ozawa (FWO), Kissinger-Akahira-Sunose (KAS) and Starink. Under slow heating conditions, the presence of oxygen led to a higher maximum pyrolysis rate in a smaller temperature interval, and the maximum pyrolysis rate shifted to the lower temperature. In oxidizing atmosphere, the pore volume and specific surface of char were about 4–5 times higher than that of the char prepared in inert atmosphere. The values of apparent activation energy (Ea) at the initial stage of pyrolysis reaction in oxidizing atmosphere were much higher than those in inert atmosphere. As the conversion rate reached 0.4–0.5, the presence of oxygen led to char gasification and combustion, as well as a considerable change in Ea values. In addition, the Ea values of biomass flash pyrolysis obtained by the fluidized bed were about 4–5 times smaller than those of slow pyrolysis obtained by TGA.

Thermogravimetric analysis and kinetic modeling of the co-pyrolysis of a bituminous coal and poplar wood

The co-pyrolysis of coal and biomass has proven to be a promising route to produce liquid and gaseous fuels as well as specific value-added chemicals while contributing to mitigating CO2 emissions. The interactions between the co-processed feedstocks, however, need to be elucidated to support the development of such a thermochemical conversion process. In this context, the present work covers the kinetic analysis of the co-pyrolysis of a bituminous coal with poplar wood. In this research, biomass was blended with coal at two different mass ratios (10% (mass) and 20% (mass)). Thermogravimetric analyses were carried out with pure and blended samples at four heating rates (5, 10, 15 and 30 °C·min−1). A direct comparison of experimental and theoretical results (based on a simple additivity rule) failed to yield a clear-cut conclusion regarding the existence of synergistic effects. Kinetic analyses have therefore been achieved using two model-free methods (the Ozawa–Flynn–Wall and Kissinger–Akahira–Sunose models) to estimate the rate constant parameters related to the pyrolysis process. A significant decrease of the activation energy has thus been observed when adding wood to coal (activation energies associated with the blend containing 20% (mass) of biomass being even lower than those estimated for pure wood at low conversion degrees). This trend was attributed to the possible presence of synergies whose related mechanisms are discussed. The rate constant parameters derived by means of the two tested models were finally used to simulate the evolution of the conversion degree of each sample as a function of the temperature, thus leading to a satisfying agreement between measured and simulated data.

Thermal decomposition characterization and kinetic parameters estimation for date palm wastes and their blends using TGA

TGA has been used to evaluate the thermal degradation profiles and kinetic parameters for the pyrolysis of date leaves, date seeds, and leaf stems and their blend at various heating rates (β) in N2. Using Kissinger–Akahira–Sunose (KAS), and Ozawa-Flynn-Wall (OFW), kinetic parameters like activation energy (E) and frequency factor (A) were estimated. The diffusion, reaction order, and power law models were used to estimate the frequency factors based on the (E) values obtained from the OFW and KAS approaches. Thermal degradation profiles showed two major loss processes: volatilization of cellulose, hemicelluloses, and lignin; and slow oxidation of the residual char. The findings demonstrated that as β increased, the TG profiles shifted to higher temperature ranges. The date palm's decomposition was not favourably reflected by the high (ΔGav) values obtained. The high (ΔSav) values obtained using OFW compared to KAS confirm these materials' high reactivity. The average activation energies (Eav) for the different parts of the date palm wastes ranged between 86 and 117 kJ/mole as predicted by the KAS method, while they were between 92 and 120 kJ/mole using the OFW method. The calculated frequency factor (A) values, evaluated by the KAS and the OFW methods, ranged between 0.0 and ∼ 0.8 × 1019min-1. The difference in (Eav) values between the KAS and OFW techniques is no greater than 8 kJ/mole. For the diffusion models of DSW, DL, and Blend, the best frequency distribution profiles are essentially normal, and the blend exhibits high frequency (A) values in a relatively constrained range of (α). That denotes quick and efficient pyrolysis. The pyrolysis index (CPI) significantly increased as β increased, indicating that pyrolysis was profitable at high heating rates. The volatile release index (Ddev) increases significantly with increasing (β) value, showing that volatiles was easier to release at a high heating rate.

Thermogravimetric Analysis and Kinetic Modeling of the AAEM-Catalyzed Pyrolysis of Woody Biomass.

This work analyzes the catalytic effects induced by alkali and alkaline earth metals (AAEMs) on pyrolysis kinetics. To this end, thermogravimetric analyses (TGA) were carried out with raw beech wood and samples impregnated with NaCl, KCl and MgCl2 at four heating rates (5, 10, 15 and 30 °C/min). Obtained results showed that AAEM compounds promote the decomposition of biomass by reducing the initial and peak pyrolysis temperatures. More specifically, the catalytic effect of the alkaline earth metal was shown to be stronger than that of alkali metals. To further interpret the obtained trends, a kinetic modeling of measured data was realized using two isoconversional methods (the Ozawa-Flynn-Wall (OFW) and Kissinger-Akahira-Sunose (KAS) models). With a view to identifying a suitable reaction model, model fitting and master plot methods were considered to be coupled with the isoconversional modeling approaches. The 3-D diffusion reaction model has been identified as being well suited to properly simulate the evolution of the conversion degree of each sample as a function of the temperature. Furthermore, the kinetic parameters derived from the present modeling work highlighted significant decreases of the activation energies when impregnating wood with AAEM chlorides, thus corroborating the existence of catalytic effects shifting the decomposition process to lower temperatures. A survey of the speculated pathways allowing to account for the impact of AAEMs on the thermal degradation of woody biomass is eventually proposed to better interpret the trends identified in this work.