Flynn Wall Ozawa Model Research Articles

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

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

Synthesis, characterization, and thermal pyrolysis mechanism of high temperature resistant phenolphthalein-based poly (arylene ether nitrile)

Phenolphthalein (PP) is usually used as a functional monomer to design novel high performance polymers with adjustable thermal, mechanical, and fluorescent properties. In this study, a soluble, amorphous, high temperature resistant PP-based poly (arylene ether nitrile) (PAEN) was synthesized and its corresponding thermal decomposition mechanism was reported via TGA/DTG, TGA/FTIR and TGA/MS analysis. PP-based PAEN showed a Tg of 250 °C a Tdmax of 503 °C and a char residue of 59.2 % at 800 °C, respectively. According to Kissinger and Flynn–Wall–Ozawa model, the activation energy of thermal pyrolysis was calculated as 225 ± 4 and 284 ± 17 kJ/mol respectively, higher than those of other poly arylene ethers. PP-based PAEN showed a three-stage thermal pyrolysis mechanism. Its initial degradation happened before 400 °C and liberated the inherent moisture. The latter backbone decomposition between 400 and 600 °C involved multiple routes mainly from the CO and CC cleavages of lactone ring, resulting in a Ph2CHPhOPh intermediate by releasing HCHO, HCOOH, CO2, H2O, CH4, C6H6, and C6H5OH. The third carbonization stage over 600 °C included the transformation from biphenyl linkages to aromatic graphite by dehydrogenation. This study not only gives a comprehensive understanding of the thermal pyrolysis behavior of PP-based PAEN, but also provides valuable references for the thermal behaviors of other PP-containing polymers.

The thermal behavior during the co-combustion of bituminous coal and oil palm trunk hydrochars

ABSTRACT Utilizing oil palm trunk (OPT) residue as a co-fuel in coal-fired plants offers an environmentally favorable solution to agricultural waste disposal and fossil fuel combustion impacts. This study investigates the potential of hydrochar from OPT (HTC-OPT) as a coal-like solid fuel for co-combustion. The combustion characteristics of coal, HTC-OPT, and their blends (10–50% HTC-OPT) were analyzed via thermogravimetric analysis with heating rates ranging from 10 to 30°C/min. The Flynn-Wall-Ozawa (FWO) and Kissinger-Akahira-Sunose (KAS) models were employed to explore co-combustion interactions and kinetic parameters. Results reveal enhanced combustion efficiency with HTC-OPT addition to coal. Higher HTC-OPT ratios correlate with increased maximum combustion rates, ignition and comprehensive combustibility indices, and decreased ignition and burnout temperatures. Additionally, blended fuels exhibit a proportionally synergistic co-combustion interaction. Both KAS and FWO models indicate similar trends in activation energies, with the lowest values (49.94 kJ/mol for KAS and 60.90 kJ/mol for FWO) at a 10% HTC-OPT ratio.

Thermal Degradation Studies of Poly(2-ethyl hexyl acrylate) in the Presence of Nematic Liquid Crystals.

The thermal degradation behavior of Poly(2-ethyl hexyl hcrylate) (Poly(2-EHA)), blended with a commercially available nematic liquid crystal (LC) mixture, was investigated by thermal gravimetric analysis (TGA). Different heating rates, ranging from 5 to 200 °C/min, were applied under an inert atmosphere. Based on the TGA results, activation energies (Eα) at different conversion rates (α) were determined using three integral isoconversion methods: Flynn-Wall-Ozawa (FWO), Tang, and Kissinger-Akahira-Sunose (KAS). It can be noticed that the global evolution of these activation energies was the same for the three models. The coefficient of determination R2 presented values generally higher than 0.97. Using these models, the Eα value for the LC remains constant at 64 kJ/mol for all conversions rates. For the polymer Poly(2-EHA), applying the Tang and FWO models, the activation energy presents a variation ranging from 80 kJ/mol, for conversion α = 0.1, to 170 kJ/mol, for α = 0.9. For the third model (KAS), this energy varies between 80 and 220 kJ/mol in the same range of α.

Insight into the thermodynamic and kinetic analysis of Tamarindus indica shell using thermogravimetric analysis

ABSTRACT The shells of Tamarindus indica could serve as a primary source of energy generation from biomass. This paper deals with non-isothermal thermogravimetric experiments conducted at heating rates of 5, 10, 15, and 20°C/min with temperatures ranging between 25°C and 700°C to evaluate the kinetic behavior and the thermodynamic properties of Tamarindus indica shell pyrolysis. Three iso-conversational models, Kissinger–Akahira–Sunose (KAS), Starink, and Flynn-Wall-Ozawa (FWO), were used to identify the activation energy (Ea), Enthalpy (ΔH), Entropy (ΔS), and Gibbs free energy (ΔG) of the Tamarindus indica shell biomass. The average activation energy when estimated using KAS, Starink, and FWO models was found to be 209.1, 209.3, and 207.5 kJ/mol with R2 values of 0.91, 0.91, and 0.92, respectively. The average ΔH, ΔS, and ΔG values using the KAS method were found to be 204.4 kJ/mol, 82.2 J/mol K, and 155.2 kJ/mol, respectively. The values of kinetic and thermodynamic triplets indicate that the reaction is non-spontaneous. The findings of this present study reveal that there is an opportunity for Tamarindus indica shells to be used as an alternative biomass fuel due to their eco-friendly nature and ideal properties.

Pyro–catalytic co–pyrolysis of Delonix regia and butyl rubber tube: Kinetic modelling and thermodynamic insights

The target of the proposed work was to compute the kinetic modelling (KM) and thermodynamic insights (TI) for the pyro-catalytic co-pyrolysis (PCCP) of Delonix regia (DR) and Butyl rubber tube (BRT). For PCCP of DR and BRT (1:1 co-feed), three different types of catalysts were utilized: zeolite (Na–Y), noble metal on activated carbon (10 wt % Pt/C), and metal oxide (1:1 wt % TiO2–ZnO) catalysts of loading between 30 and 10 wt %. For computing KM and TI, several iso-conversional models such as Friedman (FM), Flynn–Wall– Ozawa (FWO), Kissinger–Akahira–Sunose (KAS), Starink (STK), and Distributed Activation Energy Method (DAEM) were applied. At DR:BRT:Na-Y (1:1:10 wt %), the FWO model ascertained the lowest average values of activation energy Eα (kJ/mol) and pre-exponential factor A (s−1) as 180 and 5.95E+16, respectively whereas ΔH (kJ/mol) and ΔG (kJ/mol) as 175 and 180 for TI correspondingly.

Pyrolysis and kinetic behavior of neem seed biomass using thermogravimetric analysis for the production of renewable fuel

Abstract Renewable fuel is gaining more attention in the current energy crisis, and biomass is one of the potential sources of producing renewable fuel. The objective of the present research is to analyze the pyrolysis and kinetic behavior of neem seed biomass. Pyrolysis and kinetic behavior of neem seed were analyzed using thermogravimetric analysis (TGA) at different heating rates, viz. 5, 10, 15, and 20 K min−1. The kinetic study was conducted on the neem seed using various kinetic models such as Friedman, Kissinger, Flynn–Wall–Ozawa (FWO), and Kissinger–Akahira–Sunose (KAS). Thermodynamic analysis was carried out using the data extracted from the TGA curves. The results showed that the neem seed degraded in three stages, stage I: <100 °C, stage II: 100–550 °C, and stage III: >550 °C. A maximum mass loss of 73.14 % occurred at stage II owing to the loss of cellulose and hemicellulose. The activation energy determined by Friedman, KAS, and FWO models was 5.11–18.64, 10.62–57.41, and 13.77–61.51 kJ mol−1, respectively. Thermodynamic analysis revealed that the pyrolysis of neem seed was an endothermic and spontaneous process. Moreover, the previously reported average activation energy required for the pyrolysis of various seeds and shells was compared with the present study and concluded that the variation in activation energy of neem seed adheres to the outcomes reported earlier.

Gasification Characteristics and Kinetics of Lipid-Extracted Nannochloropsis gaditana

A thermal behavior study of lipid-extracted Nannochloropsis gaditana (LEA) was performed in a thermogravimetric analyzer. The study was performed by heating the sample under different heating rates (5, 10, and 15 °C/min) from room temperature to 1000 °C using N2 gas as the medium. This is crucial for thermal stability studies in a kinetic control regime. The following three stages of chemical decompositions were found: (1) moisture removal (2) devolatilization (3) fixed carbon decomposition; maximum decomposition was observed at the second stage. Activation energies of the LEA were studied using the Flynn–Wall–Ozawa model and Kissinger–Akahira–Sunose model. Main sample decomposition was observed from 100–700 °C during volatile matter evaporation. The thermal behavior study findings were used for the gasification of the sample with air to study the effect of varying reaction parameters on the compositions of the synthesis gas yield. Maximum H2 yield was found at 700 °C and 0.7 g, which were 51.2 mol% and 50.6 mol%, respectively. From the study, it was found that LEA is suitable to be used as feedstock in gasification for synthesis gas production.

Waste biomass valorisation of Bambusa vulgaris dust and Delonix regia pods: Characterization and kinetic study

The present study is focused to biomass-based exploration via physiochemical characterization of biomass waste Bambusa vulgaris dust (BD) and Delonix regia pods peels (DRP) for the enhancement of biofuels production using suitable methods. Physiochemical characteristics of the selected biomass wastes were determined using proximate and ultimate analysis, FTIR spectroscopy, elemental analysis, TGA (thermo-gravimetric analysis), and XRD (X-ray diffraction). Ultimate analysis result of BD showed good amount of lignin (18–27 %) and cellulose (48–72 %) present in it. Both BD and DRP biomasses showed the higher calorific value of ∼16 MJ/kg. Model free methods like Kissinger-Akahira-Sunose (KAS) and Flynn-Wall-Ozawa (FWO) were applied for the determination of kinetic parameters. The calculated average activation energy was 85.19 and 143.96 kJ/mol using KAS model and 84.82 and 143.32 kJ/mol using FWO model for BD and DRP biomass, respectively.

Co-pyrolysis of cashew nut, coconut shells, and rice husk waste: kinetic and thermodynamic investigations

ABSTRACT Co-pyrolysis of low ash content of coconut shell (CNS) and cashew nuts shells (CCS), and high ash content rice husk (RH) blends was performed using thermal gravimetric analysis (TGA). RH was blended with both CCS and CNS at 0, 30, 60, and 100% RH by mass. Results showed that CCS and CNS have low ash contents of 2.7 and 1.5%, respectively, while RH has high ash content of 26.7% on dry basis. TGA under nitrogen gas study was carried out at three heating rates of 10, 15, and 20 K/min. It was observed that the increase of CCS/CNS increased decomposition rates of blends. For example, RH increased from 6 to 7.7%/min when CNS was added. Furthermore, addition of low ash content leads to high decrease of maximum decomposition rates compared to high-high or low-low ash blends. Synergistic analysis has found out that a positive effect is observed when CNS/CCS is added to RH. The decrease of maximum decomposition temperature of 60–63°C compared to other studies of 10°C for all low and 40° for all high ashes is of great advantage. Flynn-Wall-Ozawa (FWO), Kissinger-Akahra-Sunose (KAS), and DAEM kinetic model analysis for 0.1 ≤ α ≤ 0.75 were used between 315 and 840°C. FWO model gave activation energy of 85, 70, and 75 kJ/mol, for RH, CNS, and CCS, respectively. Addition of low ash content biomass reduced activation energy of RH, activation energy of RH was reduced from 85 to 72 kJ/mol when CNS was added. RH requires high energy than the rest, example, RH needed 66.29 kJ/mol of energy compared to 51% of CNS and 56 kJ/mol for CCS. The entropy results were negative which implies a different orientation of molecules from origin samples properties. The Gibbs-free energies were positive and thus non-spontaneous process. Empirical models generated using SB model indicated that kinetics depends on reaction order and acceleration mechanism rather than diffusion and nuclei growth. Kinetically, the blending of high and low ash content biomass leads to high decrease of operating temperature and activation energy compared to low-low or high-high ash content blends. It has been recommended to further study on quality and quantity of product from such blends and the possibility of pre-treatment methods such as microwaves to improve pyrolysis of such blend.

Crystallization Kinetics of Hypo, Hyper and Eutectic Ni–Nb Glassy Alloys

This study presents the thermal and kinetic behavior of Ni58.5Nb41.5, Ni59.5Nb40.5, and Ni60.5Nb39.5 binary glassy alloys. The alloys ingots were obtained through an electric arc furnace and the ribbons using the melt-spinning technique at two different wheel speeds, 8 and 25 m/s. The non-isothermal study was carried out by means of Differential Scanning Calorimetry (DSC) at five different heating rates: 12.5, 15, 17.5, 20, and 22.5 K/min. X-ray Diffraction (XRD) analysis showed a fully glassy phase for all ribbons for all compositions. For both wheel speeds, the ribbons with higher Nb content were significantly thinner than those with less content. The activation energies were calculated from the Kissinger method, showing the tendency Ep1>Ex1>Eg, where Ep1, Ex and Eg denote the activation energies of first peak temperature, the first crystallization onset and glass transition, respectively. The Flynn–Wall–Ozawa model displayed a close correlation with heating rates, ribbon thicknesses, and composition. The Nb content enhanced the glassy stability since the activation energy required for crystallization increased at higher Nb concentrations.

Novel millet husk crop-residue based thermoplastic composites: Waste to value creation

The objective of the current research endeavor is to explore the potential of novel natural lignocellulosic crop-residue fibers (husk) extracted from the finger millet (Eleusine coracana) and barnyard millet (Echinochloa frumentaceae). The extracted finger millet husk (FMH) and barnyard millet husk (BMH) were characterized for their physical (extractive and density), chemical (X-ray photo spectroscopy and Fourier transform infrared spectroscopy), thermal (Thermo-gravimetric analysis), and morphological (X-ray diffraction and Scanning electron microscopy) behavior. The major objective was to explore their potential in the development of thermoplastic composites. Thermal kinetics of the fibers were studied with Flynn-Wall-Ozawa (FWO) and Kissinger-Akahira-Sunose (KAS) models. After fiber characterization, the composites were developed using injection molding process and characterized for mechanical, thermal, and morphological behavior. In the end, the flammability properties of the developed composites were investigated with Thermo-gravimetric analysis, UL-94 Horizontal burning, and Limiting Oxygen Index testing. Chemical constituent analysis reveals higher cellulosic and lower lignin content of FMH (cellulose; 38.01% and lignin; 16.25%) than BMH (cellulose; 34.5% and lignin; 21.31%). Thermal kinetics shows higher activation energy (Ea) for BMH (207.17 kJ/mol) than FMH (129.82 kJ/mol) as per the FWO model. BMH reinforced composites offer higher thermal stability and flame resistance than FMH reinforced composites, while FMH reinforced composites show higher mechanical properties than BMH reinforced composites. Overall, both husks show the potential to be used in developing thermoplastic composites.

Insights into the co–pyrolysis of olive stone, waste polyvinyl chloride and Spirulina microalgae blends through thermogravimetric analysis

Co-pyrolysis of binary and ternary blends composed of different biomass samples was analyzed based on thermogravimetric analysis (TGA). The study was carried out considering biomass samples from very different origins and uses, including Olive Stone (OS) as a representative of lignocellulosic biomass, waste Polyvinyl Chloride (PVC) as an example of a widely generated residue, and Spirulina microalgae (MA) as an archetype of a highly valuable biomass. The synergetic effects of mixing and combining these dissimilar biomass samples were evaluated. The obtained results were evaluated by four iso-conversional methods, namely Flynn-Wall-Ozawa (FWO), Kissinger-Akahira-Sunose (KAS), Starink (STK), and Modified-Friedman (M-F) to determine the activation energy and the pre-exponential factor of the process, whereas the order of reaction was calculated by Coats-Redfern model. By analyzing the correlation coefficient, the FWO model was found to better describe the thermogravimetric results for single, binary and ternary blends. The lowest and highest values of calculated activation energy correspond to OS and MA samples, obtaining values of 80.8 kJ/mol and 158.7 kJ/mol, respectively. Additionally, blending of OS, MA and PVC with a composition of 50%:25%:25% resulted in lower activation energy for ternary mixtures. The synergistic and inhibitive effects of the addition of the second and third components were also investigated according to the comparison of the experimental and theoretical mass evolutions. The results confirmed the existence of synergistic effect for the interaction between PVC-OS in the complete temperature range during the process, while the synergistic interaction between MA-OS and PVC-MA were observed above conversion values of 0.15 and 0.8, respectively. Furthermore, for all mass ratios of ternary blends, the interaction effect was inhibitive for low temperatures and then turned into synergistic for increasing temperatures.

Kinetic Analysis for the Catalytic Pyrolysis of Polypropylene over Low Cost Mineral Catalysts

A kinetic analysis of non-catalytic pyrolysis (NCP) and catalytic pyrolysis (CP) of polypropylene (PP) with different catalysts was performed using thermogravimetric analysis (TGA) and kinetic models. Three kinds of low-cost natural catalysts were used to maximize the cost-effectiveness of the process: natural zeolite (NZ), bentonite, olivine, and a mesoporous catalyst, Al-MCM-41. The decomposition temperature of PP and apparent activation energy (Ea) were obtained from the TGA results at multiple heating rates, and a model-free kinetic analysis was performed using the Flynn–Wall–Ozawa model. TGA indicated that the maximum decomposition temperature (Tmax) of the PP was shifted from 464 °C to 347 °C with Al-MCM-41 and 348 °C with bentonite, largely due to their strong acidity and large pore size. Although olivine had a large pore size, the Tmax of PP was only shifted to 456 °C, because of its low acidity. The differential TG (DTG) curve of PP over NZ revealed a two-step mechanism. The Tmax of the first peak on the DTG curve of PP with NZ was 376 °C due to the high acidity of NZ. On the other hand, that of the second peak was higher (474 °C) than the non-catalytic reaction. The Ea values at each conversion were also decreased when using the catalysts, except olivine. At <0.5 conversion, the Ea obtained from the CP of PP with NZ was lower than that with the other catalysts: Al-MCM-41, bentonite, and olivine, in that order. The Ea for the CP of PP with NZ increased more rapidly, to 193 kJ/mol at 0.9 conversion, than the other catalysts.

Simulation of the thermal degradation and curing kinetics of fly ash reinforced diglycidyl ether bisphenol A composite

Thermogravimetric Analysis (TGA) is concluding expanding applicability in determination of the thermal stability and degradation nature of materials. The present study investigates the thermal degradation behavior and the kinetics of degradation of epoxy mixed with varying percentages of 0, 2.5, 5, and 7.5 ​wt% fly ash. Thermal stability and degradation behavior of fly ash modified epoxy cast were determined by thermogravimetric analysis. The kinetic parameters of the EF composites were calculated by using Coats–Redfern, Broido and Horowitz–Metzger models under best-fit analysis and further proved by linear regression analysis. The kinetics of thermal degradation was calculated from data scanned at a heating rate of 10 ​°C/min. The obtained results reveal that kinetic parameters and thermal behavior of EF composites were improved with the reinforcement of fly ash. The cure kinetics of the varying content of fly ash reinforced epoxy cast were also studied by using a nonisothermal differential scanning calorimetric (DSC) technique at four different heating rates 5 ​°C/min, 10 ​°C/min, 15 ​°C/min and 20 ​°C/min. The curing kinetics of the EF composite was derived from the nonisothermal differential scanning calorimetry (DSC) data with the three Kissinger, Ozawa, and Flynn–Wall–Ozawa models, respectively.

RETRACTED ARTICLE: Thermal studies of biomass obtained from the seeds of Syzygium cumini and Cassia fistula L. and peel of Cassia fistula L. fruit

The potential of thermo-chemical performance of three biomass materials namely Syzygium cumini seeds (JP), Cassia fistula L. seed (AT), and Cassia fistula L. fruit peels (AP) has been investigated in detail in the present study. Thermo-gravimetric analysis (TGA) was conducted for pyrolysis kinetic parameters at various temperatures (heating rates). Five temperatures (10, 15, 20, 25, and 30 °C/min) and two model-free techniques (especially Flynn-Wall-Ozawa (FWO) and Kissinger-Akahira-Sunose (KAS)) were applied to evaluate the response. It was found that the respective average activation energies were 222.66, 200.82, and 224.57 kJ/mol for JP, AT, and AP, respectively, in the case of the FWO model, while the average activation energies 223.49, 201.19, and 227.43 kJ/mol were obtained by using the KAS model. The activation energy, enthalpy, and pre-exponential factor for the studied biomass materials are shown in the order of AP > JP > AT in both these models. Moreover, the highest values of pre-exponential factor were found for JP in FWO (1.27 × 1039) and KAS (1.81 × 1040) models. The active pyrolysis zone was also noticed in the temperature range of 175–600 °C, which represents the maximum weight loss range as well in the present study.

Investigation of Non-Isothermal Kinetics and Thermodynamic Parameters for the Pyrolysis of Different Date Palm Parts

Using the thermalgravimetric technique, we investigated the non-isothermal combustion kinetics of abundant and low-cost date palm wastes (leaflet, rachis, fibers, and their composite) as potential biomass energy sources. The kinetic and thermodynamic parameters were determined by Flynn–Wall–Ozawa (FWO), Kissinger–Akahila–Sunose (KAS), and Starink methods. Thermogravimetric analysis results showed a major peak for the degradation of volatiles between 127–138 °C with average percentage mass loss of 68.04 ± 1.5, 65.57 ± 0.6, 62.97 ± 5.5, and 59.26 ± 3.2, for rachis, composite, leaflet, and fibers, respectively. The FWO model showed the lowest activation energy, Eα, of 157 ± 25.6, 158 ± 25.7, 164 ± 40.1, and 169 ± 51.8 kJ mol−1 for the composite, rachis, leaflet, and fibers, respectively. The positive enthalpy values confirmed an endothermic pyrolysis reaction. For all models, a minimal difference of 4.40, 5.57, 6.55, and 7.51 kJ mol−1 between activation energy and enthalpy for rachis, fibers, composite, and leaflet ensued, respectively. The KAS model was best suited to describe chemical equilibrium with average ΔG values of 90.3 ± 28.8, 99.3 ± 34.9, 178.9 ± 27.3, and 186.5 ± 38.2 kJ mol−1 for rachis, fibers, composite, and leaflet, respectively. The reaction mechanism by the Malek and Popescu methods was ((g(α)=[−ln(1−α)]14) across the conversion range of 0.1–0.9 for all heating rates. The high energy content and volatile matter combined with low energy barriers make date palm waste a potential candidate in a biorefinery.

Coke combustion kinetics of spent Pt-Sn/Al2O3 catalysts in propane dehydrogenation

The kinetics of coke combustion was investigated by using a thermogravimetric analyzer (TGA) of coked catalysts which was used for propane dehydrogenation to determine the activation energy. Apart from the Pt/Al2O3 catalyst, four different Pt-Sn/Al2O3 catalysts were prepared by varying the Pt/Sn ratio from 3: 0.5 to 3: 3 by weight. The catalytic activity was measured by propane dehydrogenation at 620 °C. The reactant mixture consisting of C3H8 (30 ml/min) and H2 (30 ml/min) was fed into the reactor for 5 h. A thermogravimetric analyzer in the presence of air was used to determine the amount of coke deposited and calculate the kinetic parameters for coke combustion. Three non-isothermal models (Friedman, Flynn-Wall-Ozawa (FWO), and Kissinger-Akahira-Sunose) were used to determine the activation energy and the best model to fit the experimental data. The FWO model provided the best fit for 3Pt/Al2O3 and 3Pt-0.5Sn/Al2O3. The three models were equivalent for fitting the data for 3Pt-1Sn/Al2O3, 3Pt-2Sn/Al2O3, and 3Pt-3Sn/Al2O3. The activation energy increased with increasing Sn addition in the 3Pt/Al2O3 catalyst. Differences in the locations and the qualitative features of the cokes were suggested to interpret the results.

Artificial neural network approach for co-pyrolysis of Chlorella vulgaris and peanut shell binary mixtures using microalgae ash catalyst

Abstract The catalytic pyrolysis of pure microalgae (M), peanut shell wastes (PS) and their binary mixtures were analysed by introducing the microalgae ash (MA) as a catalyst. The pyrolysis processes were conducted at different heating rates from 10 K/min-100 K/min to observe their thermal degradation behaviour. Additionally, Artificial Neural Network (ANN) was applied by feeding the heating rates and temperatures to predict the weight loss of the samples. The kinetic and thermodynamic parameters were also determined through three different iso-conversional kinetic models: Friedman (FR), Kissinger-Akahira-Sunose (KAS) and Flynn-Wall-Ozawa (FWO). Based on the kinetic results, FWO model achieved the lowest deviation between the activation energies (Ea) from the experimental which aligned with the ANN predicted results. The finding also shows that the activation energy (Ea) of the catalytic pyrolysis of binary mixtures was lower than the pure M and PS (Experimental: 142.56 kJ/mol; ANN forecast: 131.37 kJ/mol).

Pyrolysis kinetics and reaction mechanism of the electrode materials during the spent LiCoO2 batteries recovery process

The spent lithium-ion batteries (LIBs) have potentially serious environmental hazards but contain various valuable metals. Pyrolysis has been preliminarily proven to be an efficient method to dispose spent LIBs and recycle valuable metals. However, the kinetics and reaction mechanism during this pyrolysis process still remain unclear. Therefore, in this study, the pyrolysis kinetics and reaction mechanism of a typical spent LIB (LiCoO2 battery) was investigated and revealed in depth. The results indicated that the reactions happened to the electrode materials (LiCoO2, C) were mainly in the range of 500−800 °C. Two iso-conversion methods (Kissinger–Akahira–Sunose model and Flynn–Wall–Ozawa model) could both well describe the pyrolysis process, and the corresponding activation energies obtained were 389.61 and 405.67 kJ/mol respectively. The physicochemical properties of the pyrolysis products were detailedly characterized to reveal the reaction mechanism. The pyrolysis reaction mechanism of the electrode materials was firstly proposed and divided into three stages: firstly, LiCoO2 was decomposed into CoO, O2 and Li2O; then Li2O reacted with CO2 to form Li2CO3; finally CoO was reduced and converted into Co. This study is expected to provide a comprehensive understanding of the pyrolysis kinetics and reaction mechanism during the spent LiCoO2 batteries recovery process.