Kissinger Equation Research Articles

An assessment of the mechanically alloyed equiatomic FeCoNiMnSi high entropy amorphous alloy for non-isothermal crystallization kinetics and magnetocaloric refrigeration application

We studied an equiatomic FeCoNiMnSi high entropy amorphous alloy successfully processed via mechanical alloying technique. The structural, magnetic, and magnetocaloric characteristics of the resulting materials were examined using X-ray diffraction, field emission scanning electron microscopy, high-resolution transmission electron microscopy, and a vibrating sample magnetometer. The structural analysis showed a prominent amorphous phase formation as the milling time increases from t = 0–35h of mechanical alloying. The differential scanning calorimetry was employed to investigate the non-isothermal crystallization kinetics of the 35-h milled sample. The results revealed that the milled powder consists of a single exothermic peak with its apparent activation energy (Eg, Ex, Ep) being determined using the Kissinger, Ozawa, and Augis-Bennett equations. The findings exhibit Ex > Ep > Eg, representing that nucleation is more complicated than the growth mechanism during the crystallization process. Meanwhile, under non-isothermal conditions, the Kissinger-Akahira-Sunose, Friedman, and Flynn-Wall-Ozawa models were calculated using the local activation energies that agree with the apparent activation energy. Furthermore, the Johson-Mehl-Avrami-Kolmogorov exponent (n) and Avrami-Ozawa combined [F(T)] models exhibit high-dimensional nucleation and growth with an increasing nucleation rate enabled by lowering the local activation energies as a function of degree of conversion with respect to temperature. In magnetic measurements, a feasible mathematical model was proposed as a novel strategy for predicting the value of saturation magnetization as a milling time function. The model has an exceptional predictive capability, confirmed by fitting other research outcomes. Finally, the proposed system also delivers the best magnetocaloric properties with a maximum magnetic entropy change of 3.70 Jkg−1 K−1 at 150 K curie temperature and a refrigeration capacity of 252.86 J/kg with 1000 Oe applied magnetic field.

Preparation, characterization and thermal properties of nitrographene coated aluminum powder

AbstractAluminum powder is commonly used as a metal fuel additive in composite solid propellants. However, its tendency to agglomerate during combustion can lead to two‐phase flow losses, negatively impacting its energy performance. To address this issue and enhance the combustion performance of aluminum powder, nitrated graphene oxide (NGO) was developed to improve aluminum dispersion and optimize its energy characteristics. Various analytical techniques were employed to examine its properties, including Fourier‐transform infrared spectroscopy (FT‐IR), scanning electron microscopy (SEM), X‐ray photoelectron spectroscopy (XPS), elemental analysis (EA), differential scanning calorimetry (DSC), and thermogravimetric analysis (TG). Al/NGO composite was prepared using a solution‐assisted method in N, N‐dimethylformamide (DMF) and characterized by SEM, XPS and X‐ray diffraction (XRD). The ignition characteristics and heat of combustion of Al/NGO powder were measured using a laser igniter and an oxygen bomb calorimetry. The appropriate mass ratios of NGO coating had positive effects on the ignition and combustion of Al. Specially, 4 % NGO coating reduced Al ignition energy by 46.5 % and increased the Al combustion efficiency by 22.0 %. Moreover, the catalytic effect of Al/NGO on the thermal decomposition of ammonium perchlorate (AP) was investigated using differential thermal analysis (DTA). Results showed that two‐stage pyrolysis paths of AP tended to merge into a single pyrolysis process when Al/NGO4 % was added. The most favorable catalytic effect on AP′s thermal decomposition process was produced with the addition of 10 % Al/NGO4 %, reducing the activation energy by Kissinger equation for high‐temperature decomposition to 107.7 kJ mol−1. These findings may provide valuable insight for enhancing the performance of aluminum powder in energetic materials through NGO modification.

Kinetics of crystallization and soft magnetic properties of Co72Fe8B10Si10 amorphous alloys

Co72Fe8B10Si10 amorphous alloy was prepared in an Ar atmosphere using a single roller rapid quenching technique at a wheel speed of 25 m/s. The prepared ribbons were annealed for 1 h at temperatures ranging from 473 to 773 K. X-ray diffractometer was used to observe the microstructure transformation. Field emission scanning electron micrographs exhibit mosaic type structures that become more prominent with increasing annealing temperature. Energy dispersive X-ray spectroscopy was also utilized to observe the concentrations of elements. The Kissinger and Ozawa equations were utilized to determine the amorphous alloy's crystallization activation energy. The two methods revealed consistent findings in their calculations. At 473 K, the obtained maximum real initial permeability (μ′max) is 376 which remains unchanged up to 10 kHz, whereas for 573 K, μ′max is noted to be 361 to 100 kHz. Other magnetic parameters such as loss factor, quality factor, and relative quality factor were also investigated for the Co72Fe8B10Si10 amorphous alloy to elucidate its suitability in such materials based devices.

Composition design and crystallization behavior of Zr–Cu–Ni–Al bulk metallic glasses

The Zr–Cu–Ni–Al system was explored in this study, and seven new compositions of Zr-based bulk metallic glasses (BMGs) were designed by combining different proportions of binary eutectic phases Zr38Cu62, Zr76Ni24 and Zr51Al49, and rod-like shape samples were prepared with different diameters using the copper mold casting method. Modifying the proportion coefficient of these eutectic units, the width of the supercooled liquid region was increased from 79 to 95 K, and the thermal stability of the prepared metallic glass was improved. Differential scanning calorimetry was used to investigate the non-isothermal and isothermal crystallization behavior of the prepared samples. Noticeably, there was a small low-temperature exothermic peak before the glass transition temperature Tg in the non-isothermal crystallization process, which was related to the structural relaxation. The crystallization transition activation energy fitted by the Kissinger equation had the same variation trend as that obtained by the Arrhenius equation. Among the four metallic glasses studied, the glassy phase of Zr55·5Cu23·25Ni9Al12.25 was more stable, showing higher glass transition activation energy and longer incubation time. In addition, the isothermal crystallization processes of four metallic glasses were studied according to the Johnson-Mehl-Avrami (JMA) model. The calculated average Avrami exponents were >2.5, indicating that the nucleation rate increased during the isothermal crystallization process.

Parameter estimation of epoxy resin cure kinetics by dynamics DSC data

AbstractThis study focused on determining the curing kinetic parameters of amine‐epoxy resin by performing dynamic DSC tests. The Kissinger and Crane equations were used to determine the activation energy, the pre‐exponential factor, and the reaction order as kinetic parameters for curing. The Ozawa equation was also used to determine the activation energy that changes at different levels of cure during the reaction. The average activation energy obtained by the Ozawa method was compared with the Kissinger activation energy. In addition, the T‐β extrapolation method was used to determine the optimum curing temperature. The kinetic parameters obtained from the Kissinger and Crane equations were used in the nth‐order kinetic model to predict the degree of cure at a given time and temperature. The linear regression fitting method was used in Minitab software to determine the curing parameters. The results were evaluated based on the fitting parameters. This study provides a theoretical basis for the curing mechanisms of epoxy matrix fiber composites used in the manufacture of wind turbine blades.

Construction of [P4442]2[IDA]/Zirconium Metal‐Organic Framework (UiO‐66) for Curing with Epoxy Resin

AbstractCuring agents for epoxy resin (EP) are one of the most important branches in the polymer materials field due to their enormous potential in many fields, but constructing them in a well‐controlled curing temperature remains challenging. Herein, a novel curing agent is constructed by the zirconium metal‐organic framework (UiO‐66) and [P4442]2[IDA] through an impregnation method. [P4442]2[IDA]@UiO‐66 is utilized as a functional nanofiller and curing agent to construct the [P4442]2[IDA]@UiO‐66/EP nanocomposites. The chemical structures of [P4442]2[IDA]@UiO‐66 were investigated by XRD, SEM, DSC, and TG characterizations. The various [P4442]2[IDA]@UiO‐66 with different loading amounts of [P4442]2[IDA] were used to investigate the curing behaviors of the EP‐51. The DSC results confirm that the curing temperature of the [P4442]2[IDA]@UiO‐66/EP is higher than that of [P4442]2[IDA]/EP. In addition, the kinetic parameters and the activation energy of the curing reaction were acquired according to the fitting of Kissinger equation and Ozawa equation. The drying time of [P4442]2[IDA]@UiO‐66/EP system at 40 °C was enhanced 17 times compare to that of [P4442]2[IDA]/EP system. This study opens new avenues for the rational design of EP nanocomposites by employing ionic liquids@MOFs composite materials as curing agent for wide engineering applications.

Hydrogen isotope effect on thermodynamic and kinetic properties of Pd based ternary alloys: Pd–Ag-M (M = Au, Zr)

Owing to the importance of hydrogen and its isotopes in energy sector, the present study investigates thermodynamic and kinetic hydrogen isotope effects on desorption reaction of newly synthesized Pd-based ternary alloy-hydrides/deuterides viz., Pd0.89Ag0.05M0.06 (M = Au, Zr)–H/D. Alloys were prepared by arc melting method followed by characterization using PXRD, SEM, TXRF and EDX techniques. The effect of hydrogen isotopes on thermodynamics of H2/D2 desorption reaction was investigated by generating pressure-temperature isotherms (PCIs) at various temperatures using a Sieverts' type volumetric apparatus. The PCT diagram of alloys depicts a single plateau which confirms desorption to be a one-step process. Both alloy systems display a normal isotope effect as indicated by higher plateau pressure for deuterides as compared to hydrides. The enthalpy and entropy changes for the desorption reactions were calculated using Van't Hoff equation. The separation factor derived from PCT data indicates that Pd0.89Ag0.05Au0.06 alloy has a significantly high separation factor as compared to other Pd based alloys reported in the literature. To get more insight into this behavior, non-isothermal kinetic analysis of H2/D2 desorption based on Differential Scanning Calorimeter (DSC) data acquired at four different heating rates was conducted and activation energies of desorption were calculated by invoking Kissinger's equation. The activation energies of alloys were found to be lower than that of palladium which explains the high separation factor of alloys as compared to Pd. The desired combination of higher separation factor and lower activation energy makes Pd0.89Ag0.05Au0.06 alloy a promising material for practical application in the separation of hydrogen isotopes via self-displacement gas chromatography (SDGC).

Crystallization Behavior of Copolyesters Containing Sulfonates.

The polar sulfonate groups in cationic dyeable polyester (CDP) lead to complex crystallization behavior, affecting CDP production's stability. In this study, cationic dyeable polyesters (CDP) with different sulfonate group contents were prepared via one-step feeding of sodium isophthalic acid-5-sulfonate (SIPA), terephthalic acid (PTA), and ethylene glycol (EG). The non-isothermal crystallization behavior of these copolyesters was analyzed by differential scanning calorimetry (DSC). Results show that the crystallization temperature of the sample shifts to lower values with the increase in SIPA content. The relaxation behavior of the molecular chain is enhanced due to the ionic aggregation effect of sulfonate groups in CDP. Therefore, at low cooling rates (2.5 °C/min and 5 °C/min), some molecular chain segments in CDP are still too late to orderly stack into the lattice, forming metastable crystals, and melting double peaks appear on the melting curve after crystallization. When the cooling rate increases (10-20 °C/min), the limited region of sulfonate aggregation in CDP increases, resulting in more random chain segments, and a cold crystallization peak appears on the melting curve after crystallization. The non-isothermal crystallization behavior of all samples was fitted and analyzed by the Jeziorny equation, Ozawa equation, and Mo equation. The results indicate that the nucleation density and nucleation growth rate of CDP decrease with the increase in SIPA content. Meanwhile, analysis of the Kissinger equation reveals that the activation energy of non-isothermal crystallization decreases gradually with the increase in SIPA content, and the addition of SIPA makes CDP crystallization more difficult.

Cure Kinetics and Thermal Decomposition Behavior of Novel Phenylacetylene-Capped Polyimide Resins.

Based on a novel phenylacetylene capped polyimide (PI) with unique high-temperature resistance, its curing kinetics and thermal decomposition behavior were investigated. The curing mechanism and kinetics were studied by differential scanning calorimetry (DSC), and the activation energy (Ea) and pre-exponential factor (A) of the curing reaction were calculated based on the Kissinger equation, Ozawa equation, and Crane equation. According to the curve of conversion rate changing with temperature, the relationship between the dynamic reaction Ea and conversion rate (α) was calculated by the Friedman equation, Starink equation, and Ozawa-Flynn-Wall (O-F-W) equation, and the reaction Ea in different stages was compared with the results of molecular dynamics. Thermogravimetric analysis (TGA) and a scanning electron microscope (SEM) were used to analyze the thermal decomposition behavior of PI resins before and after curing. Temperatures at 5% and 20% mass loss (T5%, T20%), peak decomposition temperature (Tmax), residual carbon rate (RW), and integral process decomposition temperature (IPDT) were used to compare the thermal stability of PI resins and cured PI resins. The results display that the cured PI has excellent thermal stability. The Ea of the thermal decomposition reaction was calculated by the Coats-Redfern method, and the thermal decomposition behavior was analyzed. The thermal decomposition reaction of PI resins at different temperatures was simulated by molecular dynamics, the initial thermal decomposition reaction was studied, and the pyrolysis mechanism was analyzed more comprehensively and intuitively.

Examining The Phase Formation of Aging and Shallow Cryogenic Process Applied to Aluminum Alloys with Thermal Analysis

In this study, cryogenic treatment was applied to the 7*** series alloy, which is one of the aluminum alloys frequently used in the aviation and space industry, after the retrogression and re-aging process, and the phase formations were examined by thermal analysis. First of all, solution heat treatment was applied at 480 °C for 2 hours and water was given. After quenching, artificial aging heat treatment was applied at 120 °C for 24 hours. To start the RRA (retrogression and re-aging) heat treatment, after artificial aging, retrogression was performed at 200 °C for 10 minutes and quenched. Then, re-aging was performed at 120 °C for 24 hours and the aging process was completed. After the RRA heat treatment, cryogenic treatment was applied for 2 hours at -40 °C, -80 °C respectively. The heat treated samples were analyzed with a differential thermal analyzer and the transformations of GP, η′ and η phases were found. Since the η′ phase is known as the strength-increasing phase in the structure, the activation energies of each sample were calculated using the Augis-Bennet and Kissinger equations. The results showed that the activation energy of the sample treated with -40 cryogenic treatment was 50% less than the sample without cryogenic treatment. This situation proved with the Arrhenius equation that the formation of the η′ phase would be easier.

Study on the Pyrolysis Characteristics of Tobacco Stems Under Different Steam Explosion Pressures

Thermal weight loss behavior of tobacco stems is the key to studying the chemical properties of tobacco stalks. In this research, four steam explosion pressure gradients with three heating rates were investigated for the pyrolysis characteristics of tobacco stems. Three methods were employed to analyze pyrolysis reaction kinetics. The results showed that pyrolysis of tobacco stems consists of three phases: dehydration, degradation, and carbonization. The influence of steam explosion pressure on the thermal stability of tobacco stems was as follows: 0.5 MPa > 0.2 MPa > 0.8 MPa > block sample > 1.1 MPa. The pyrolysis of tobacco stems followed the first-order reaction kinetics equation, and the pyrolysis experiments fit the Kissinger equation, Tang equation, and Hu-Gao-Zhang equation well. The experimental results provide a reference for research on the subject of pyrolysis of tobacco stems.

Insights into the structure sustainable evolution and crystallization kinetics of amorphous Mg60Ni30La10 alloy

Nanocrystalline materials have wide potential applications due to the special properties, which can be easily prepared by nanocrystallization of the amorphous alloys. In this work, phase transformations of the melt-spun amorphous Mg60Ni30La10 alloy were characterized by in-situ XRD and TEM. The results showed that during crystallization Mg2Ni first formed from the amorphous matrix followed by LaMg3, LaMg2Ni and LaMgNi4. The phase transformation was completed rapidly, with nucleation progressing more prominently than grain growth. Nucleation and grain growth during crystallization were discussed according to Avrami index n(α) based on Kissinger equation. In addition, the classic Miedema theory was introduced to estimate the crystallization temperature and the nucleation frequency. Nucleation behaviors are closely related to the phase structures formed during the amorphous crystallization from the view of thermodynamics. This work provided a preliminary basis for controlling the evolution of amorphous/nanocrystalline structure of alloys.

All-Nitrogen Energetic Material Cubic Gauche Polynitrogen: Plasma Synthesis and Thermal Performance.

Numerous theoretical calculations have demonstrated that polynitrogen with an extending polymeric network is an ultrahigh-energy all-nitrogen material. Typical samples, such as cubic gauche polynitrogen (cg-N), have been synthesized, but the thermal performance of polynitrogen has not been unambiguously determined. Herein, macroscopic samples of polynitrogen were synthesized utilizing a coated substrate, and their thermal decomposition behavior was investigated. Polynitrogen with carbon nanotubes was produced using a plasma-enhanced chemical vapor deposition method and characterized using infrared, Raman, X-ray diffraction X-ray photoelectron spectroscopy and transmission electron microscope. The results showed that the structure of the deposited polynitrogen was consistent with that of cg-N and the amount of deposition product obtained with coated substrates increased significantly. Differential scanning calorimetry (DSC) at various heating rates and TG-DSC-FTIR-MS analyses were performed. The thermal decomposition temperature of cg-N was determined to be 429 °C. The apparent activation energy (Ea) of cg-N calculated by the Kissinger and Ozawa equations was 84.7 kJ/mol and 91.9 kJ/mol, respectively, with a pre-exponential constant (lnAk) of 12.8 min-1. In this study, cg-N was demonstrated to be an all-nitrogen material with good thermal stability and application potential to high-energy-density materials.

Non-isothermal curing kinetics of soybean oil-based resins: Effect of initiator and reactive diluent

Soybean oil has been utilized as a raw material to develop biobased polymer to replace petroleum-based counterparts due to its abundance, renewability, and molecular designability. Acrylated epoxidized soybean oil (AESO) is a commercially available product and has been used in coatings, plasticizers, and composites. The curing of AESO resins normally refers to the free-radical polymerization of CC bonds, which is closely related to the types of initiators and reactive diluents (RDs). In this work, the processing parameters and curing kinetic mechanism of AESO resins were investigated based on the extrapolation method, Kissinger, Crane, and Friedman equations, and the influences of initiators and RDs on the curing of the resins were explored. Results indicated that the types of initiators significantly affected the processability and curing kinetics of AESO resins, and the curing temperatures and reaction activation energy of the resins were strongly associated with the decomposition temperature and activation energy of the initiators. The number of CC bonds and molecular structure of RDs considerably influence the curing characteristics of the resins. The addition of RDs endowed the reaction more complexity, and the activation energy significantly depended on the level of CC conversion.

Preferential formation of the stereocomplex crystals of poly(L‐lactide) and poly(D‐lactide) blend by epoxidized soybean oil under nonisothermal crystallization

AbstractFormation of stereocomplex crystals (SCs) in enantiomeric poly(L‐lactide) (PLLA) and poly(D‐lactide) (PDLA) blends is an effective way to improve the heat resistance and mechanical performance of polylactide (PLA) products. However, obtaining PLAs with high stereocomplex content is not straightforward as the homocrystal and SCs occur simultaneously and compete with one another. In this work, various amounts of epoxidized soybean oil (SO) or SO at 3%–20% by weight were added to equal amounts of the stereoisomers (PLLA/PDLA; 50/50). From differential scanning calorimetry, it was found that epoxidized SO increased the crystallization temperature, facilitated the SC crystallization, and suppressed the homecrystal formation, whereas SO did not affect the crystallization behavior for the racemic blends. Moreover, epoxidized SO reduced the glass transition temperature, cold crystallization temperature, and melting temperature of the racemic blends. We examined how epoxidized SO affected the crystallization of PLLA/PDLA at cooling rates from 2 to 20°C/min. We discovered that epoxidized SO still encouraged SC crystallization. The activation energy, calculated from Takhor and Kissinger equations, indicated that adding 5 wt% epoxidized SO effectively promoted the crystallization and facilitated the SC formation of the PLLA/PDLA blend.

Characterization of enalapril maleate: An approach using thermoanalytical, thermokinetic and spectroscopic techniques

Enalapril maleate is a widely used drug for the treatment of cardiovascular diseases. Its mechanism of action is to inhibit the angiotensin-converting enzyme selectively. Therefore, it is metabolized to enalaprilat by liver cells. The thermal behavior of enalapril maleate was investigated by simultaneous thermogravimetry and differential scanning calorimetry (TG-DSC), and evolved gas analysis by simultaneous thermogravimetry and differential scanning calorimetry coupled infrared spectroscopy (TG-DSC-FTIR). The results provided information on thermal stability, purity, thermal decomposition steps, and the main products formed in the heating. The enalapril maleate was found to be stable up to 148 ?C. Above this temperature causes thermal degradation of the substance, which occurs in two stages in an inert atmosphere (N2) and three stages in an oxidizing atmosphere (air). Through the TG-DSC-FTIR the released gases were identified as maleic anhydride as a thermal decomposition intermediate. DSC analysis showed that the material obtained 99.5% purity, which indicates high purity. Employing both the Kissinger and Friedman equations, alongside Model Fitting methods, the study reveals key insights. The Kissinger method unveils an apparent activation energy of 47.07?15.45 kJ mol?? for the complete thermal breakdown, a finding corroborated by the Friedman method. Model Fitting methods, the article applies them, yielding an apparent activation energy of 55.70?3.4 kJ mol?? with a three-dimensional diffusion thermal degradation model.

Thermal Stability of Electrodeposited Fe-55wt%Ni Alloy and Effect of Low-Temperature Heat Treatment on Magnetic Properties

Electrodeposited nanocrystalline soft magnetic materials have emerged as one of the hottest research topics in the field of magnetic materials due to they are easy to implement in miniaturization, lightweight, and energy-saving of electronic devices. The thermal stability and grain growth process of electrodeposited Fe-55wt%Ni alloy were investigated. Results indicated that the grain growth was rapid at a temperature of about 678 K, while the exothermic peak appeared in DSC with an exothermic heat of about 12 ± 1 J g−1. The activation energy for grain growth was obtained through the optimized Kissinger equation and isothermal kinetics calculations, and the growth mechanism was evaluated based on the calculation results. Below 678 K, the activation energy required for grain growth was low, which implied the growth mechanism was the rearrangement of atoms at the grain boundary; Above 678 K, the growth mechanism was grain boundary diffusion. After the low-temperature heat treatment, the coercivity (H c) decreased and the saturation magnetization (M s) increased slightly, which was attributed to the reduction of internal stress and the ultra-fine nanocrystalline structure. The optimal heat treatment process was 573 K heat treatment for 5 h, where M s and H c of 160 emu g−1 and below 1 Oe, respectively.

Effect of sigma (σ) phase precipitation on the recrystallization kinetics of AISI 904L superaustenitic stainless steel

Microstructural evolutions, σ-phase precipitation, and recrystallization kinetics of cold-rolled AISI 904L stainless steel during annealing were studied in the present work. The microstructure and hardness evolution were different in the temperature ranges of T < 950 °C (with σ-phase precipitation) and T ≥ 950 °C. The former range was associated with the fall of hardness due to recrystallization softening, followed by hardening due to the concurrent σ-phase precipitation; while the latter range was associated with the continuous fall of hardness. Using the Johnson–Mehl–Avrami–Kolmogorov (JMAK) analysis, the recrystallization activation energy in these ranges were respectively determined as 325 and 257 kJ/mol, where the higher activation energy in the former range was correlated to the retardation effect of the σ-phase. Via applying the Kissinger's equation to the differential scanning calorimetry (DSC) results, the activation energy of ∼332 kJ/mol was obtained, which was consistent with the precipitation of the σ-phase.

Phase transformation kinetics of high-carbon steel during continuous heating

Effects of heating temperature, heating rate, and holding time on the austenitization process of near-eutectoid high-carbon steel have been investigated. The dilatometric tests were carried out at different heating rates of 1–100 °C/Sec. The Ac1 and Ac3 critical temperatures, the volume fractions of the parent and produced austenite phases, and consequently, the coefficient of the Johnson–Mehl–Avrami–Kolmogorov (JMAK) equation were obtained from dilatometric diagrams. The activation energy for the transformation was estimated using the Kissinger equation. The optical microscope was used for the microstructural characterization of samples austenitized at different temperatures and durations. The grain growth kinetics of austenite during processing was also characterized. Cellular Automata simulation was used to investigate the nucleation and growth of austenite from the initial full pearlitic structure. Based on the results, the activation energy of 242.6 kJ/mol at low heating rates (1 °C/Sec to 12 °C/Sec) and 436.94 kJ/mol at high heating rates (25 °C/Sec to 100 °C/Sec) were obtained, which indicated the different phase transformation mechanisms. This was attributed to the presence of boron, which postpones nucleation at grain boundaries and helps to activate the shear mechanism at high heating rates. Finally, a continuous heating transformation (CHT) diagram was drawn, which is an indispensable tool to consider the effect of heating rate on the austenitization process and austenite grain size.

Thermo-catalytic decomposition of walnut shells waste over cobalt doped cerium oxide: Impact of catalyst on kinetic parameters and composition of bio-oil

This research work is aimed at investigating the pyrolysis of walnut shells mixed with cobalt doped cerium oxide and non-catalytic pyrolysis of walnut shells. The pyrolysis experiments were performed in a locally designed pyrolysis chamber. The oils from catalytic and non-catalytic pyrolysis were characterized with GC–MS. It was found that in case of catalytic pyrolysis, the bio-oil obtained has several short-chain compounds as compared to bio-oil obtained through non-catalytic pyrolysis. Thermogravimetric analysis was conducted to assess the kinetics of pyrolysis of biomass both with and without catalyst. The kinetic parameters were determined using Kissinger equation. The activation energy (Ea) values for the decomposition of hemicelluloses, cellulose, and lignin were found as 167.72, 181.35, and 191.22 kJ mol−1 for non-catalytic pyrolysis and 107.48, 121.79, and 137.57 kJ mol−1 for catalytic pyrolysis. Moreover, the optimumtemperature of pyrolysis was effectively reduced to 410 °C employing a catalyst, as opposed to the maximum temperature of 430 °C in the case of non-catalytic pyrolysis. Keeping in view the reduction in activation energy and improvement in quality of oil from catalyzed reaction in presence of cobalt doped cerium oxide, it can be concluded that the findings of this study can contribute to the development of a process for sustainable utilization of walnut shells as energy source.