Flynn-Wall-Ozawa Research Articles

Property Prediction of Ag-Filled Isotropic Conductive Adhesive through the Analysis of Its Curing and Decomposition Kinetics

In this study, various thermal analyses were carried out on a self-developed and commerce-oriented Ag-filled isotropic conductive adhesive (ICA) and its unfilled matrix resin through which glass transition temperature (Tg) and thermal endurance could be quantitatively predicted. An autocatalyzed kinetic model was used to describe the curing reaction, which was proven to be in good consistency with the experimental data. The activation energies for the curing reaction of the ICA and the matrix resin were determined to be 68.1 kJ/mol and 72.9 kJ/mol, respectively, which means that the reaction of the ICA was easier to occur than its unfilled matrix resin. As a result, the time–temperature profile could be calculated for any Tg requested based on the kinetic model of curing and the DiBenedetto equation. Further, the thermal decomposition stability of the ICA and its unfilled matrix resin were also studied. The activation energies for the thermal decomposition of the ICA and the matrix resin were calculated to be 134.1 kJ/mol and 152.7 kJ/mol, respectively, using the Ozawa–Flynn–Wall method, which means that the decomposition of ICA was easier to occur. The service life of the resin system at a specific temperature could therefore be calculated with their activation energy. The addition of micro-scale Ag flakes did not change the curing and decomposition mechanisms by much.

Co-pyrolysis of coal slime and cattle manure by TG–FTIR–MS and artificial neural network modeling: Pyrolysis behavior, kinetics, gas emission characteristics

In this study, Thermogravimetric-Mass spectrometry-Fourier transform infrared spectrometry (TG-MS-FTIR) were used to study the co-pyrolysis behavior and gaseous products of coal slime (CS) and cattle manure (CM). By establishing different artificial neural network (ANN) prediction models, it was found that MLP13 model is the best prediction model. It was determined that the pyrolysis process of CM and CS can be divided into three stages, of which the second stage has the largest mass loss. Due to the different mixing ratio, there will be synergistic interaction or inhibitory effect during co-pyrolysis of CM and CS. Adding CM to CS will improve the pyrolysis performance of CS. The Kissinger-Akahira-Sunose (KAS) and Flynn-Wall-Ozawa (FWO) methods were used to calculate the activation energy. The activation energy was the lowest when the mixing ratio is CM:CS = 7:3, which was 195.377 kJ/mol (FWO) and 195.008 kJ/mol (KAS), respectively.

Pyrolysis of low-value waste switchgrass: Physicochemical characterization, kinetic investigation, and online characterization of hot pyrolysis vapours

The present study is dedicated to physicochemical characterization, kinetic, thermal degradation behaviors, and online characterization of vapour products through Py-GC–MS and TGA-FTIR. The feasibility study was attained via proximate, ultimate, fibre analysis, and extractive analysis, whereas Vyazovkin (VM), Ozawa-Flynn-Wall (OFW), Kissinger-Akahira-Sunose (KAS), Coats-Redfern (CR), and Distributed Activation Energy Model (DAEM) were employed for kinetics exploration. The feasibility study showed its tremendous ability to be used as pyrolysis feedstock. TGA-FTIR documented the maximum release of CO2 (26.22%), carbonyls (25.04%), and hydrocarbons (15.93%). Further, kinetic investigation of SWG documented an increased trend of activation energy against progressive conversion. The apparent average activation energy from KAS, OFW, DAEM, and VM was found to be 126.03, 137.54, 130.33, 134.26 kJ mol−1, respectively. Also, kinetics reaction mechanisms are exposed to the multi-nature of decomposition of biomass. Furthermore, the Py-GC–MS investigation established increased hydrocarbons (6.49–11.54%) and reduced oxygen-containing products (24.17–17.27%) with an increased temperature

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.

Investigation on oxygen-controlled sewage sludge carbonization with low temperature: from thermal behavior to three-phase product properties.

A comprehensive study was conducted on the characteristics of oxygen-controlled carbonization process of sewage sludge (SS) using thermogravimetric analysis and lab-scale carbonization experiment. Reaction temperature of SS carbonization was varied between 250 and 650°C in carrier gas with different O2 contents. The thermal process of SS in low oxygen could be divided into three stages: dehydration (below 160°C), devolatilization (160-380°C), stubborn volatile decomposition and fixed carbon combustion (380-600°C). Based on Kissinger-Akahira-Sunose (KAS) and Flynn-Wall-Ozawa (FWO) methods, the reaction activation energy (E) of SS carbonization process in 10% O2 was the lowest, with values of 98.50kJmol-1 (KAS) and 103.49kJmol-1 (FWO). The properties of the obtained char, tar, and gas products were analyzed by FTIR and GC-MS. With the increase of carbonization temperature, char yield decreased and gas yield increased. The highest yield of tar was 27.76% (N2) and 27.04% (10% O2) at 450°C. Low-oxygen atmosphere at the same temperature did not change the yield of char but increased the fixed carbon content and its aromaticity. Oxygen would participate in secondary cracking in tar and promote gas generation above 350°C. It was found that the presence of oxygen not only increased the concentration of H2, CO, and CH4 in gas product, but also improved the quality of tar in terms of high aromatic content and low nitrogen-containing compounds.

Synthesis and characterization of novel sulfonamide functionalized maleimide polymers: Conventional kinetic analysis, antimicrobial activity and dielectric properties

In this study, novel maleimide monomers, N-sulfamethoxazole maleimide(SMM), and N-sulfanilamide maleimide(SAM) were synthesized. Homopolymers of SMM and SAM were obtained by free radical polymerization method in 1,4-dioxane solvent at 65 °C. The structural characterizations of monomers and their homopolymers were carried out via FTIR, 1H- and 13C-NMR techniques. The glass transition temperature (Tg) of the polymers was determined using differential scanning calorimetry (DSC). Using the thermogravimetric analysis (TGA) method determined the thermal stability of the polymers. The thermal degradation activation energies (Ea) of the polymers were calculated by Kissinger, Flynn Wall Ozawa (FWO), and Kissinger-Akahira-Sunose (KAS) methods. The biological activities of compounds have been also studied on various bacteria and fungi. The weight average (Mw) and number average (Mn) molecular weights of the polymers were determined by gel permeation chromatography (GPC). Photochemical properties of polymers were investigated with ultraviolet (UV) and fourier transform infrared (FTIR) spectra. In addition, some physical constants of polymers such as density, solubility parameter, and viscosity were determined. Finally, the dielectric constant, dielectric loss factor and ac conductivity values ​​of the polymers were estimated in the frequency range of 100 Hz–20 kHz.

Thermogravimetric analysis kinetic study of Spirulina platensis residue pyrolysis

Bio-oil from microalgae pyrolysis has excellent potential to be developed as a renewable, sustainable, and environmentally friendly energy fuel. Using pyrolysis technology to use the solid waste from microalgae extraction of spirulina platensis as an energy source is a solution for pollution due to biomass extraction. The solid residue is known as Spirulina Platensis Residue (SPR). SPR pyrolysis will produce liquid fuel (bio-oil), gas, and biochar. This paper discusses the study of the pyrolysis kinetics of SPR with Thermogravimetric analysis (TGA) by flowing nitrogen, the settlement method using Kissinger - Akahira - Sunose (KAS) and Flynn -Wall - Ozawa (FWO). The samples were heated at a temperature ranging from 30°C to 1000°C with three different heating levels, namely 10, 30, and 50°C/min yang injected 20 mL/min Nitrogen (N2). The results obtained from the thermal decomposition process show three main stages, namely dehydration, active and passive pyrolysis. The activation energy (Ea) and the pre-exponential factor (A) obtained by the KAS method were around 42.241 kJ/mol, 51.290 kJ/mol, 54.556 kJ/mol, and 61.604 kJ/mol with conversion of 0.2%, 0.3%, 0.4%, while the estimation of activation energy from FWO 48.963 kJ/mol, 58.107 kJ/mol, 61.498 kJ/mol, and 68.457 kJ/mol with conversion of 0.2%, 0.3%, 0.4%, and 0.5% respectively. the kinetic parameter can be described by using this method. The experimental results show that the kinetic parameters obtained from the two methods are slightly different. However, the KAS and FWO methods are quite efficient in explaining the mechanism of the degradation reaction.

Catalytic pyrolysis of coconut oil with Ni/SBA-15 for the production of bio jet fuel.

Catalytic pyrolysis of vegetable oil is one of the potential routes to convert oil to drop-in biofuels, known as renewable hydrocarbons. In this paper, we explored catalytic pyrolysis of coconut oil using SBA-15 impregnated with Ni in proportions of 1% to 5% to produce sustainable aviation fuel. The catalysts were synthesized, calcined and then characterized by XRD, FTIR, SEM, and EDS. In order to better understand the behavior of this process, thermal and kinetic studies were carried out by thermogravimetry. The TG curves of vegetable oil with (10%) and without catalysts were obtained at heating rates of 5, 15 and 20 °C min−1, in the temperature range between 30 and 600 °C. The kinetic parameters were calculated by the Ozawa–Flynn–Wall (OFW) and Kissinger–Akahira–Sunose (KAS) methods. In the kinetic study, lower heat rates promoted higher conversions and the KAS model suits the process. The results calculated for the OC sample using the two kinetic models showed an increase in the Ea energy as the conversion progressed to a certain point. Catalytic pyrolysis experiments were performed in a one-stage tubular reactor at 500 °C with a catalyst loading of 10 wt% on the basis of mass of oil. The catalyst with 5% Ni showed greater presence of hydrocarbons and greater formation of water, indicating that the deoxygenation process occurred through decarbonylation. With this, the present study was successful in the development of methodologies for obtaining hydrocarbons with a composition close to that of drop-in fuels, compared to the process carried out with vegetable oil in the absence of catalysts.

Pyrolytic thermal degradation kinetics of pigeon pea stalk (Cajanus Cajan): Determination of kinetic and thermodynamic parameters

This article highlights the pyrolytic thermal degradation behavior of pigeon pea stalk (PPS) at different heating rates (β) ranging from 10 to 40 °C/min in inert nitrogenous atmosphere using the thermogravimetric analysis (TGA). Three isoconversional methods: Flynn-Wall-Ozawa (FWO), Kissinger-Akahira-Sunose (KAS) and Starink method were used to evaluate the kinetic parameters, including activation energy (Ea) and pre-exponential factor for range of conversion degree (α) 0.1 to 0.9. The highest average value of activation energy for PPS was found 126.24kJmol−1 for FWO method followed by Starink and KAS method as 122.59kJmol −1 and 116.23kJmol −1 respectively. Pre exponential factor (A) and thermodynamic parameters such as change in Gibbs free energy (G), enthalpy (ΔH) and entropy (ΔS) were computed and critically discussed. The average value of ΔH was found as 117.36, 110.95 and 120.97kJmol −1 for FWO, KAS and Starink method, respectively. Whereas, ΔG values were noticed very close to each other (ranges from 302 to 315kJmol −1) and average values of ΔS were − 181, −192 and −185Jmol−1K−1 for OFW, KAS and Starink method, respectively. The difference between average activation energy and value of ΔH was noticed imperceptible (∼5kJmol −1), which is a positive confirmation about the generation of green product from PPS requiring low energy potential. As summary PPS was found to have significant potential to be used as a feedstock for bioenergy production.

Study of thermal decomposition parameters of UHMWPE sheet

Thermal decomposition of UHMWPE (ultra-high molecular weight polyethylene) sheet is studied at 5 °C/min heating rate, utilizing TGA/DTA technique. The measurements are performed in the temperature region 50–500 °C, in the presence of nitrogen environment. The decomposition of UHMWPE shows four different stages. The present measurements are used to find various kinetic parameters like activation energy, pre- exponential and thermodynamic factors by adopting two different kinetic models (Flynn-Wall-Ozawa (FWO) and Coats and Redfern (CR)).

Thermogravimetric analysis on the characteristics of oxy-fuel co-combustion of sub-bituminous coal and semi-coke

The co-combustion of the low-rank coal with coal derived semi-coke is of great significance to solve the urgent problem of excessively produced semi-coke in China. In this research, the oxy-fuel co-combustion characteristics of Zhundong sub-bituminous coal with bituminous coal derived semi-coke are systematically investigated using thermogravimetric analysis. Compared with air combustion, oxy-fuel atmosphere increased the ignition and burnout temperature by 10 and 40 °C, respectively. Increasing the oxygen concentration to 30% strongly compensated for the slight reduction of the combustion parameters under oxy-fuel condition and much better co-combustion performance was obtained. Three iso-conversional methods, namely, Flynn-Wall-Ozawa (FWO), Kissinger-Akahira-Sunose (KAS) and Starink, were applied to estimate the activation energy, which can be divided into two stages during the co-combustion process. The average activation energy of sub-bituminous coal, the blend and semi-coke were 49.31, 50.82 and 59.00 kg/mol, respectively. Further, the pre-exponential factor and thermodynamic parameters of the enthalpy change, Gibbs free energy change and entropy change were calculated. Interaction indices were innovatively used for both kinetic-thermodynamic parameters and DTG values. An obvious interaction can be observed during the co-combustion process. The kinetic and thermodynamic results demonstrated that the 30% semi-coke ratio was beneficial to co-combustion. Meanwhile, X-ray fluorescence (XRF) and ash fusion analyses proved that the slagging tendency of sub-bituminous coal ash reduced by blending of semi-coke.

Carbothermal reduction of fayalite: Thermodynamic and non-isothermal kinetic analysis

The present paper investigated the thermodynamics and kinetics of carbothermal reduction of fayalite by non-isothermal method combining with thermogravimetric analyzer and applying the Flynn-Wall-Ozawa (FWO) and M?lek models. According to the thermodynamic analysis, the starting temperature of direct reduction reaction of fayalite was 806.79? in the standard state. The indirect reduction reaction could not take place in the standard state. While the volume percentage of CO was higher than 86 vol.% in nonstandard state, the indirect reduction could take place in the range of experimental temperature. Meanwhile, Boudouard reaction could promote the indirect reduction process. The kinetic analysis results showed that at the temperature below 1100?, the main reduction reaction was the direct reduction between fayalite and graphite. With the temperature increasing, the fayalite reacted with CO generated from the gasification of graphite. When the reduction rate increased from 0% to 50%, the activation energy of the reaction increased to 524.41 kJ/mol. Then, the activation energy decreased with the increase of reduction rate. The carbothermal reduction of fayalite was a multistep reaction. The controlling step in the initial stage was the gasification of graphite. As the reaction proceeded, the generated CO provided a good kinetics condition for the carbothermal reduction of fayalite, and the controlling step of the reaction was the nucleation and growth of the metallic iron.

Effect of Nickel Nanopowder on the Thermal Degradation of Coal Tar Distillate

Regularities of influence of nickel nanopowder on the thermal degradation of coal tar distillate were deter-mined using model-free Kissinger, Flynn-Wall-Ozawa and model-fitting Coats-Redfern methods. Coal tar distillate with a boiling point of <350 °C was obtained by simple distillation of primary coal tar from the Shubarkol deposit. Nickel nanopowder was used as a catalyst and was added to coal tar distillate in a quantity of 1 % of the mass of the distillate and then the process of thermal degradation of coal tar distillate was con-ducted at heating rates 5, 10 and 20 °C/min in an inert gas medium. Nickel powder was obtained by high-voltage discharge impact on the dc electrolysis. X-ray diffraction (XRD) analysis showed that the obtained nickel powder has face-centered cubic structure and the average crystallite size calculated by the Scherrer equation was ~ 34 nm. Calculations of activation energy were performed via processing of thermogravimetric data. The Kissinger method showed that the activation energy value decreases from 145.19 kJ/mol to 43.65 kJ/mol, by the Flynn-Wall-Ozawa (FWO) method the value decreases from 152.82 kJ/mol to 51.65 kJ/mol, and by the Coats-Redfern method the value decreases from 143.38 kJ/mol to 52.64 kJ/mol. Ap-plicability of these methods is ensured by the high values of correlation coefficients.

Kinetics of Thermolysis of a Low-Temperature Tar in the Presence of a Catalyzer Agent with Deposited Metals

The thermal decomposition of low-temperature coal tar (LTCT) obtained from the coals of Shubarkol Komir JSC of the Republic of Qazaqstan in the presence of nanocatalysts with metal oxides (iron, cobalt and nickel) supported on microsilicate was studied for the first time. Microsilicate acts as a carrier and catalyst. Microsil-icate is a product of the Karaganda silicon plant of “Tau-Ken.temir” LLP. The main chemical component of the original microsilicate is silicon oxide. The individual and chemical phase composition of the microsilicate was determined using X-ray spectral analysis. The particle size of the initial microsilicate and the mixture of microsilicate with metal oxide catalysts (nickel, cobalt, and iron) was determined using a nanosizer. Stages of thermal decomposition of LTCT and a mixture of LTCT with catalysts under conditions of programmed heat-ing up to 640 °С in a nitrogen atmosphere have been established. On the basis of thermogravimetric analysis, the kinetic parameters (activation energy, mass loss rate, and pre-exponential factor) of LTCT pyrolysis and mixture with added catalysts were determined. The modeless integral isoconversion Ozawa–Flynn–Wall method was used to determine the kinetic parameters. The values of the activation energy for the thermal de-struction of the LTCT in the absence and presence of the nanocatalyst ranged from 54.04 to 297.5 kJ/mol. A kinetic compensation effect was revealed, probably due to the multicomponent composition of the LTCT and the influence of added catalysts to the LTCT. The thermogravimetry method showed a high effect of the sup-ported catalysts on the thermal degradation of LTCT. This method was used to determine the values of the ac-tivation energy and the pre-exponential degradation factor for the LTCT and the mixture with catalysts at dif-ferent heating rates, which allows a detailed interpretation of the thermal analysis data. The obtained results of the kinetics of decomposition of LTCT can be used to create a database for mathematical modeling of the process of processing this type of raw material.

Gördes Lateritinin CO Atmosferinde İzotermal Olmayan İndirgenme Kinetiği

The growing demand for nickel metal and the depletion of high-grade sulfide ore reserves have turned the direction of industry towards laterites which are not desirable as the primary source due to their low Ni content and more energy-intensive processing. Thus, alternative routes are essential for effectively processing these ores while reducing the costs and greenhouse gas emissions. Solid-state reduction followed by magnetic separation is an attractive option for recovering the nickel in laterites. Hereby, this study analyzed the non-isothermal reduction kinetics of nickel laterite from Gördes (Manisa, Turkey) by CO at different heating rates of 20, 25, 30, 35, and 45 ºC/min. The activation energies were determined by Friedman (FR), Kissinger-Akahira-Sunose (KAS), and Flynn-Wall-Ozawa (FWO) methods, and the controlling mechanisms were determined by the Malek interpretation of the Sestak-Berggren Equation. The reduction process was divided into three stages which take place between "0 to 0.16", "0.16 to 0.45", and "0.45 to 0.7" reduction degrees respectively according to the kinetic analysis results. The first stage was determined to be interface reaction controlled (with "Ea" of 53 kJ/mol), while the second and third were determined to be mixed controlled (with "Ea" of 126 kJ/mol and 379 kJ/mol, respectively).

The preparation of novel core–shell suppressor and its suppression mechanism on coal dust explosion flame

To explore ways of further guaranteeing the production safety of coal processing, novel powder suppressors with core–shell structure were prepared through anti-solvent crystallization method by loading potassium oxalate (K) and ferric citrate (T) on treated waste molecular sieve. Flame propagation experiments were performed to investigate the effects of suppressors prepared under different conditions on coal dust flame propagation. The results showed that when K and T were added simultaneously at the loading of 30 wt%, the suppressor S@T-K showed best suppression performance. The pyrolysis-oxidation mechanism of coal dust with and without suppressor S@T-K was analyzed using Coats-Redfern (C-R) method. After the suppressor was added, the activation energy increased by 11.55 kJ/mol and 15.37 kJ/mol in the rapid and slow pyrolysis stages, respectively. The activation energy values of the coal sample with and without the suppressor under different conversion ratios were further calculated using Flynn-Wall-Ozawa (FWO) and Kissinger-Akahira-Sunose (KAS) methods. The average activation energy values during the rapid and slow pyrolysis stages both agree well with the C-R calculation, which verifies the appropriateness of using C-R method to identify the reaction mechanism. By combining the coal dust flame propagation behaviors with the pre- and post-explosion characterization results, it is proposed that waste molecular sieve composite powders with core–shell structure suppress flame propagation through the synergy of physical and chemical reactions.

Effect of torrefaction temperature on spent coffee grounds thermal behaviour and kinetics

The paper aimed to investigate the influence of the torrefaction temperature (210, 235, 260 °C) on the kinetic and thermodynamic parameters, as well as the reaction mechanism during combustion of spent coffee grounds (SCGs). Non-isothermal thermogravimetric experiments were carried out at four heating rates, namely, 5, 7, 10, and 15 °C/min. Thermogravimetric (TG) and differential thermogravimetric (DTG) results showed torrefaction temperature firstly increases and then decreases the combustion reactivity, reaching the best value for the sample SCGs-235. Starink, Kissinger-Akahira-Sunose (KAS) and Ozawa-Flynn-Wall (OFW) iso-conversional models, master plots method and the compensation effect method were used to calculate the combustion kinetic triplet of the samples. The activation energy of the samples decreased with torrefaction temperature increasing, from 199.76 kJ/mol to 168.91 kJ/mol (with the Starink model). All the combustions were best explained by a reaction order model whose order decreased with the elevated torrefaction temperature and the heating rate of the combustion process. Using kinetic parameters obtained from the Starink method, thermodynamic parameters (enthalpy, Gibbs free energy, and entropy) were also determined, showing that SCGs seemed to be more suitable for the torrefaction at 235–260 °C. The study findings can provide practical information for modelling and designing combustion reactors for clean biofuel production from SCGs.

Kinetic modelling for pyrolytic conversion of dedicated short rotation woody crop with predictions for isothermal, non-isothermal and stepwise heating regimes

Sesbania sesban, a promising short rotation woody crop, was first evaluated in order to assess its physicochemical attributes as a feedstock material in biochar manufacturing. Additionally, thermogravimetric analysis (TGA), performed at 0.5, 1, 4 and 8 °C.min−1, was utilised to conduct thermal analysis, with the results being used to analyse the feedstock's kinetic behaviour during thermal degradation in an inert environment. For the first time, advanced kinetics and technology solutions (AKTS) software was used to analyse the kinetic parameters of sesbania pyrolysis and make kinetic predictions under various thermal conditions. The apparent activation energy (Ea) was determined using Friedman's differential iso-conversional model, which is the primary kinetic modelling method utilised. Other traditional models, such as the integral Flynn-Wall-Ozawa (FWO) and ASTM-E698 methods, were employed for comparison purposes. The activation energy of 124.53 kJ.mol−1 was obtained using the ASTM-E698 technique, while the Ea value for the FWO method ranged from 50 to 200 kJ.mol−1. As it accurately reflects the dynamic nature of lignocellulosic biomass degradation, the differential iso-conversional technique is the most reliable and precise approach, with Ea values ranging from 20 to 205 kJ.mol−1. Predictions under isothermal, step-based and non-isothermal conditions were then constructed using the results computed through the differential iso-conversional model. This information can be used to improve production throughput in a variety of reactors. Additionally, the derived kinetic parameters can be used for process modelling.

Thermal degradation of calcium lactate pentahydrate using TGA/FTIR/MS: thermal kinetic and thermodynamics studies

ABSTRACT The objective of this study is to investigate the thermal degradation kinetics and thermodynamics of the calcium lactate pentahydrate (CLP) crystals by means of a thermogravimetric analyzer (TGA) at four different heating rates from 25°C to 1000°C in N2 atmosphere. First, the CLP crystals were precipitated at pH 6 and 25°C in a batch-type crystallizer and the obtained crystals were characterised by X-ray powder diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR). The XRD result showed that the calcium l-lactate pentahydrate (L-CLP) was the only crystalline phase produced. Then, the activation energy and pre-exponential factor of thermal degradation were determined based on the Coats–Redfern, Flynn–Wall–Ozawa (FWO), Kissinger–Akahira–Sunose (KAS), and Starink models. The degradation reaction order was determined as 1.5 by Coats-Redfern model. The average activation energy of the CLP was 34.7, 33.0, and 33.3 kJ/mol for the FWO, KAS, and Starink models, respectively. Thermodynamic parameters as changes in enthalpy, entropy and Gibbs free energy were calculated depending on the conversion degree. Finally, TGA in combination with FTIR and mass spectrometer (MS) was utilised to detect the evolved gases during the degradation of CLP. H2O and CO2 were identified as the main evolved products.

Effect of Pyrolysis Atmosphere on the Gasification of Waste Tire Char

The aim of the study is to assess the influence of the atmosphere during pyrolysis on the course of CO2 gasification of a tire waste char. Two approaches were used: the pyrolysis step was carried out in an inert atmosphere of argon (I) or in an atmosphere of carbon dioxide (II). The examinations were carried out in non-isothermal conditions using a Rubotherm DynTherm thermobalance in the temperature range of 20–1100 °C and three heating rates: 5, 10 and 15 K/min. Based on the results of the gasification examinations, the TG (Thermogravimetry) and DTG (Derivative Thermogravimetry) curves were developed and the kinetic parameters were calculated using the KAS (Kissinger-Akahira-Sunose) and FWO (Flynn-Wall-Ozawa) methods. Additionally, the CO2 gasification of tire chars reaction order (n), was evaluated, and the kinetic parameters were calculated with the use of Coats and Redfern method. Tire waste char obtained in an argon atmosphere was characterized by lower reactivity, which was reflected in shift of conversion and DTG curves to higher temperatures and higher mean values of activation energy. A variability of activation energy values with the progress of the reaction was observed. For char obtained in an argon atmosphere, the activation energy varied in the range of 191.1–277.2 kJ/mol and, for a char obtained in an atmosphere of CO2, in the range of 148.0–284.8 kJ/mol. The highest activation energy values were observed at the beginning of the gasification process and the lowest for the conversion degree 0.5–0.7.