Variation Of Activation Energy Research Articles

Comprehensive Understanding of the Heavy Oil Combustion Process: Reaction Behavior, Kinetic Triplet, and Mechanism Implication.

In this work, thermo-oxidative behavior, kinetic triplet, and free radical mechanism of ultraheavy oil during an in situ combustion (ISC) process were systematically surveyed via multiple thermal analysis techniques (TG/DTG/DSC/PDSC), model-free methods, and related mathematical simulation. First, specific mass loss, exothermic intensity, and corresponding temperature intervals were respectively determined in low-/high-temperature oxidation (LTO/HTO) regions. In addition, the comparison of atmospheric/pressurized differential scanning calorimetry (DSC/PDSC) experiments indicated that the pressurized conditions could obviously strengthen the oxidation progress with more heat emission. Then two model-free methods were contrastively employed for PDSC data to calculate LTO and HTO activation energy variations with the conversion rate. Moreover, the acceleratory rate model for LTO and the Sestak-Berggren model for HTO were accordingly picked as the most probable mechanism functions, which were later used to determine the simulated curves. Then, the simulations of α-T and dα/dT-T curves were respectively attained using Friedman equation in MATLAB software and contrasted with experimental data to validate the accuracy of the yielded kinetic triplet and forecast the combustion behavior. Further, the evolution pathways of the underlying oxidation mechanism was illustrated. This study updates the understanding of the nonisothermal combustion process, contributing to the subsequent numerical simulation and feasible investigation for in situ combustion implementation to enhance heavy oil recovery.

A modification to the Friedman and Ortega isoconversional methods for evaluation of the activation energy as a function of conversion and temperature

The Friedman and Ortega isoconversional methods typically apply linear regression to the isoconversional kinetic data for calculation of activation energy solely as a function of extent of conversion. However, in complex reactions, activation energy depends on both conversion and temperature. Our modification involves quadratic curve fitting instead of linear regression, resulting in the determination of activation energy as a function of conversion and temperature. The new technique enables the calculation of the temperature dependence of activation energy for different heating rates, making it a valuable addition to isoconversional analysis. The conventional and modified approaches were utilized on the isoconversional kinetic data concerning polyethylene thermal degradation. The results provided a more detailed representation of the variations in activation energy when nonlinear regression was used.

Estimating shelf life and degradation mechanisms of nitrile butadiene rubber for viscoelastic dampers

This study investigates the shelf life of nitrile butadiene rubber (NBR) based on age and temperature factors. Natural aging of nitrile butadiene rubber samples is performed under laboratory conditions for 2 years, followed by thermogravimetric analysis to evaluate Arrhenius parameters. Toop’s equation is used to predict shelf life at 5% conversion rate. Model-free kinetic methods, including Ozawa-Flynn-Wall (OFW), Kissinger-Akahira-Sunose (KAS), and Kissinger, estimate shelf life at different temperatures for both virgin and naturally aged nitrile butadiene rubber. Results show close correlation between KAS and Kissinger methods, with slight variations in activation energy impacting shelf life. Fourier-transform infrared spectroscopy (FTIR) tests assess functional group changes with age. Virgin nitrile butadiene rubber activation energy: OFW-73.33 kJ/mol, KAS-68.43 kJ/mol. Aged nitrile butadiene rubber activation energy: OFW-72.57 kJ/mol, KAS-67.88 kJ/mol. Shelf life at 40°C: Virgin nitrile butadiene rubber - OFW-111.29 years, KAS-26.31 years. Aged nitrile butadiene rubber - OFW-89.01 years, KAS-22.37 years. These findings provide valuable insights for predicting and assessing nitrile butadiene rubber viscoelastic damper performance in engineering applications.

High-throughput determination of the interdiffusion coefficients and atomic mobilities in bcc Ti–Fe–V alloys

A comprehensive understanding of diffusion kinetics of the Ti–Fe–V system is crucial for elucidating the solidification process in high-strength titanium alloys. In this paper, ten sets of diffusion couples within bcc Ti–Fe–V alloys that underwent annealing at temperatures of 1273K, 1323K, and 1373K were prepared. Composition-distance curves were determined using the electron probe microstructure analysis technique. Atomic mobility parameters and interdiffusion coefficients were obtained using the numerical inverse method with the assistance of HitDIC software. It should be noted that the atomic mobility parameters for Ti–Fe and Ti–V were reoptimized using the most up-to-date thermodynamic descriptions. This approach enables the acquisition of comprehensive data regarding the temperature-composition relationship in diffusion. D˜FeFeTi exhibits a markedly greater value compared to D˜VVTi. Both D˜FeFeTi and D˜VVTi demonstrate an increase with the increase of temperature. Furthermore, the Arrhenius equation can be applied to solve for the variation in frequency factors and activation energies concerning temperature and composition.

SYNTHESIS AND DIELECTRIC CHARACTERIZATION OF MnO ADDED ZnO-TeO2-B2O3 GLASSES

Using the conventional melt-quench technique, a glass system of specific composition 20ZnO- (28-x) Te2O3-52B2O3: x mol% MnO where 'x' varies from 0.5 to 2.0 was synthesized. All the prepared glass samples were examined for their solid-state behavior by XRD and SEM those confirm the non-crystalline state. In this work, three important dielectric properties were experimentally measured across 1 to 100 kHz frequency and room temperature to 200oC range. These parameters show an increasing trend with dopant which confirms the growing degree of disorder due to trivalent manganese ions that acted as modifiers with large concentrations. However, the reasons for variation in activation energy including other dielectric parameters are discussed in detail through the oxidation states of manganese ions and their structural changes.

The influence of B doping on phase formation and microstructural evolution in NHL during solid-state reactions

Natural Hydraulic Lime (NHL), was synthesized by doping B2O3 into calcium carbonate and silica aerogel. By introducing varying levels of B3+ ion doping (0/1/5/10/15/20/25 mol%), a range of NHL compositions were successfully prepared, thereby enabling regulation of the NHL phase composition. Furthermore, through the doping of 25 mol% B3+ ions, in-depth investigations employing XRD, SEM, and FT-IR were conducted to explore phase transitions and ion migration during NHL calcination at different temperatures. Thermal analysis kinetics studies further revealed the variation of activation energies for CaCO3 decomposition and C2S crystallization with changing levels of B3+ ion doping. The introduction of B ions was observed to stabilize the α’ phase of dicalcium silicate (C2S) and moderately enhance the reactivity of calcium oxide (CaO). B3+ ions significantly influenced the crystallization mechanism of C2S, shifting it from a diffusion-controlled process to a heterogeneous nucleation process. The application of the Kissinger and Flynn-Wall-Ozawa (FWO) methods assisted in elucidating the underlying reasons for these differences. Both approaches demonstrated a substantial decrease in activation energy, signifying the pronounced influence of B doping on the sintering regime and phase transition mechanism of NHL. In summary, the precise modulation of NHL phase composition and sintering regime was achieved through B doping. These findings not only deepen our understanding of the mechanistic role of B3+ ions in NHL preparation and application but also offer robust guidance for the production process of NHL.

Synthesis, optical characteristics and thermal stability of Mn4+-doped Na3GaF6 red-emitting phosphor for high-performance warm WLED

Nowadays, Mn4+-activated fluoride red phosphors with high color purity, strong zero phonon line emission and relatively short decay time are crucial for improving the optical performance of WLED and emerging applications. In this work, a series of red-emitting Mn4+-activated fluoride phosphors in consideration of the non-equivalent substitution of Mn4+ for Ga3+ in the Na3GaF6 host are synthesized via the coprecipitation method at room temperature. The use of different reaction solvents successfully regulates the morphology, size and luminescence intensity of the phosphor. Under blue light excitation, Na3GaF6:Mn4+ sample shows a bright narrow-band red emission with exceptional correlated color temperature (4029 K). Moreover, the emission of strong zero phonon line induces the outstanding color purity of red light (93%). In addition, the critical concentration of Mn4+ is determined to be 0.04 and the concentration quenching mechanism is also systematically discussed. Noticeably, when Na3GaF6:Mn4+ phosphor achieves maximum fluorescence emission, its fluorescence lifetime value is only 3.48 ms. Additionally, the theoretical calculated results demonstrate that Na3GaF6 host can provide strong crystal field strength for Mn4+, and the Racah parameters (B and C) and nephelauxetic ratio (β1) are used to evaluate the nephelauxetic effect of Mn4+, which is compared with other types of Mn4+-activated phosphors. The activation energy, chromaticity shift and chromaticity coordinate variation are systematically calculated to analyze the thermal stability of Na3GaF6:Mn4+ red phosphor. Meanwhile, by employing the as-prepared phosphor Na3GaF6:Mn4+ as a red component, a high-performance warm WLED shows a full spectrum emission, and the corresponding cold white light emission is also transformed into the warm white light emission (CCT = 4224 K, Ra = 89.1 and LE = 111.72 lm/W). Moreover, under high driving current, such WLED exhibits stable output light efficiency. These results suggest that Na3GaF6:Mn4+ as red phosphor has a stupendous potential for warm WLED in indoor lighting.

Complex dielectric and impedance analysis in Dy1-XPrXMnO3 compounds: Partial substitution effects

Synthesis and characterization of single phasic Dy1-xPrxMnO3 (DPMO) ceramic samples through solid-state reaction (SSR) method are reported in present study. XRD analysis confirmed the structural formation of DPMO and revealed lattice changes induced by Pr substitution that affect JT-distortion and tilting of MnO6 octahedra. Fine-grained microstructures with a micrometre-sized grain size were observed using FESEM images, which increased with increasing Pr concentration. The variation of activation energy in DPMO was found to be induced by modification in Mn–O bond distances. The dielectric behaviour of DPMO was significantly enhanced, which was explained using the UDR model fitting. Impedance analysis confirmed the existence of non-Debye type relaxation and negligible electronic polarization mechanisms in all DPMO samples. With the increase in temperature, a reduction in the magnitude of Z' was observed, indicating a decrease in the resistance of contributing electroactive components such as grains, grain boundaries, and electrode interfaces. Electric modulus studies revealed the existence of grain and grain boundary relaxation processes throughout the studied frequency and temperature range in DPMO compounds. Overall, the study provides deep insights into the effect of Pr substitution on the structural, electrical, and dielectric properties of DPMO and highlights the potential of DPMO for future electronic and energy device applications.

The exploration of pyrolysis characteristics, kinetics and product distribution of Bermuda grass via TG, Py-PIMS and Shuffled Complex Evolution

The pyrolysis behaviors of biomass play an important role in understanding energy utilization. The pyrolysis characteristics, kinetics and product distribution of Bermuda grass were investigated based on thermogravimetric (TG), pyrolysis with photoionization mass spectrometry (Py-PIMS) and Shuffled Complex Evolution algorithm (SCE). The temperature range for weight loss is 450–850 K and the pyrolysis process can be classified into two regions based on the variation of activation energy, with conversion rates of 0.10–0.40 (Region Ⅰ) and 0.40–0.75 (Region Ⅱ). According to the Flynn-Wall-Ozawa (FWO) and Kissinger-Akahria-Sunose (KAS) methods, the mean activation energy values for Region Ⅰ are 126.70 kJ/mol and 124.20 kJ/mol, respectively. while the values for Region Ⅱ are 161.70 kJ/mol and 159.90 kJ/mol, respectively. Then, a three-component parallel reaction model based on the SCE algorithm was proposed and the pyrolysis kinetic parameters were optimized. The results showed the predicted values using the optimized kinetic parameters are well agreeable with experimental data, which shows that the optimized kinetic parameters and the three-component parallel reaction model may be applicable to the Bermuda grass pyrolysis. Moreover, the Py-PIMS results confirmed that the fast pyrolysis products of Bermuda grass included furan derivatives, ketones, cyclopentanones, phenols, aromatic hydrocarbons, acids and esters.

Innovative Morphology Control Method: Modulating Metal Ratios in NixCoP@NF for Hydrogen Evolution Reaction

AbstractThe use of non‐precious metal materials for catalyzing the hydrogen evolution reaction (HER) holds significant importance for the widespread application of new energy technologies. In this study, we prepare a novel foam nickel (NF) supported NixCoP (NixCoP@NF) nanocrystal through a one‐pot hydrothermal method and high‐temperature phosphorization, involving a straightforward process. Innovatively, we achieve morphology control of NixCoP@NF by altering the Ni : Co ratio to maximize its active surface area. The resulting ′petal‐like′ Ni0.5CoP@NF nanostructure exhibits high activity and long‐term durability in an alkaline medium (1 M KOH), with an overpotential of 58 mV at a current density of 10 mA ⋅ cm−2, a Tafel slope of 60.82 mV ⋅ dec−1, and demonstrates lower impedance compared to most non‐precious metal HER electrocatalysts. Furthermore, the variation in activation energy (Ea) reflects the thermodynamic advantages during the electrolysis process. This work offers a new approach for the development of simple and cost‐effective HER catalysts.

Kinetic and thermodynamic study of pyrolysis of the hydrolyzed residue of rice straw and husk by subcritical water process using thermogravimetric analysis

AbstractThe use of hydrolyzed rice straw (HRS) and hydrolyzed rice husk (HRH) as feedstock for pyrolysis was evaluated through kinetic and thermodynamic studies. HRS and HRH were obtained from subcritical water hydrolysis (SWH) at different temperatures (180, 220, and 260°C). The Coats‐Redfern method was used to analyze the thermal behavior through thermogravimetry (TG) and derivative thermogravimetry (DTG) curves. TG profiles showed higher decomposition in the range of 250–400°C, especially for rice straw (RS) and HRS (80 wt %). The pyrolysis curves were well predicted by a first‐order reaction model. The kinetic analysis showed a variation in activation energy (EA) between 24.3 to 41.3 kJ mol−1 and 40.4 to 54.7 kJ mol−1 for RS/HRS and rice husk (RH)/HRH, respectively. The enthalpy (ΔH), Gibbs free energy (ΔG), and entropy (ΔS) varied from 25.9 to 39.6 kJ mol−1, 35.4 to 69.6 kJ mol−1, and −64.1 to −6.7 J mol−1 K−1, respectively, for RS/HRS, and 35 to 49.8 kJ mol−1, 43.2 to 79.3 kJ mol−1, and −53.5 to −10.2 J mol−1 K−1, respectively, for RH/HRH. These results showed that the pyrolysis reactivity using HRS is higher than HRH, which indicates the pyrolysis of HRS is more advantageous than HRH.

Solid phase synthesis of alkoxyl tin and the role of alkyl for Multi-stage thermal decomposition of polyvinyl chloride

To prepare an innovative thermal stabilizer for polyvinyl chloride (PVC), the micro-nano powders of alkoxyl tin (RxOSn) were synthesized via a solid phase reaction at room temperature, using the surfactant sodium benzene sulfonate (SBS) as a catalyst. Theoretical calculation of deprotonation reaction energy of monobasic alcohol and tin chloride was performed with the framework of DFT, and their structures were characterized by XRD, SEM, FT-IR, XPS, and its surface wetting performance was carried out by contact angle (CA). Meanwhile, the multi-stage thermal stability of PVC with 10% RxOSn sample, and the role of alkyl groups (Rx, x = 2 ∼ 5) in the RxOSn/PVC were investigated. The results show that the RxOSn samples exhibit a microstructure akin to the rutile of SnO2. Multi-stage kinetic studies of exothermic reactions has confirmed that the alkoxyl wetting performance of stabilizers becomes a determining factor, while the variation in activation energy (Ea) values seems to be mainly influenced by the Rx alkyl groups in the RxOSn samples. Besides, the differences in the lattice parameter a of RxOSn were validated to have a certain impact on the stabilizing effect of PVC, and the Ea of PVC degradation is closely related to the relative value of exposed crystal surfaces (D(110)/D(101)). This series of materials is easily synthesized and can effectively enhance the thermal stability of PVC, offering a wide range of potential applications.

Oxidation behaviors of Hongqian heavy crude oil characterized by TG-DSC-FTIR-MS within full temperature regions

To better understand in-situ combustion (ISC) theory and reveal the oxidation behavior and mechanism of Hongqian (HQ) heavy crude oil, the thermo-oxidative characteristics and kinetics of HQ heavy oil were studied under air conditions using TG-DSC-FTIR-MS technique. According to the TG/DTG-DSC curves, the oxidation reactions of HQ heavy oil can be divided into low temperature oxidation (LTO), fuel deposition (FD) and high temperature combustion (HTC) stages. The reaction mechanism for each reaction interval was comprehensively analyzed by online FTIR and MS analysis. In FTIR spectra, H2O, hydrocarbon, CO2, CO, –COOH, and aromatic ring were observed during the oxidation process, which are used to explain the occurrence of the possible decomposition/isomerization of hydroperoxides in the later stage of LTO and the important role of light hydrocarbons evaporation, thermal oxidative cracking and polycondensation for coke formation at FD stage, coke combustion at HTC stage, as well as the possible hysteresis of dehydrogenation and aromatization at FD and HTC stages. The strong variation of activation energy with conversion degree confirms the complex oxidation reactions. MS analysis of H2, CH4, H2O, CO, O2, and CO2 produced during oxidation process helps to verify these reaction mechanisms; and provide more information about the in-situ H2 generation and the conditions where H2 generation may occur as well as the generation of CO and its possible reaction mechanism in LTO reactions. These obtained data aid in a deeper insight into crude oil oxidation mechanism and provide reference for establishing accurate reaction scheme and reaction kinetic model for the precise simulation of ISC processes.

Zirconia Incorporated Aluminum Phosphate Molecular Sieves as Efficient Microporous Nano Catalysts for the Selective Dehydration of Methanol into Dimethyl Ether

Annually, a growing demand was noted for replacing petroleum fuels with second-generation eco-friendly fuels like dimethyl ether (DME). Methanol dehydration into DME process has been considered as one of the potential pathways for the manufacture of a clean fuel. However, stable, and active catalyst is exceedingly requisite for generation of DME particularly at reasonably low temperature. In the current study, zirconia incorporated AlPO4 tridymite microporous molecular sieve catalysts were fabricated by a hydrothermal method in the presence of triethylamine (TEA) as a structure directing agent. The catalysts were characterized by X-ray diffraction (XRD), energy dispersive X-ray (EDX), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and N2-sorption assessments. Catalysts’ acidity was estimated by decomposition of isopropanol, pyridine and dimethyl pyridine chemisorption, and pyridine-TPD. Results revealed that catalysts surfaces composed acid sites of Brønsted nature and of weak and medium strengths. Activity results showed that 1 wt% H2SO4 modified zirconia incorporated AlPO4-TRI catalyst calcined at 400 °C presented the best activity with a conversion of 89% and a 100% selectivity into DME at 250 °C. The significant catalytic activity is well-connected to the variation in BET-surface area, acidity, and activation energy of methanol dehydration. The catalysts offered long-term stability for 120 h and could be regenerated with almost the same activity and selectivity.Graphical

Evaluation of the non-isothermal crystallization kinetics of the (Zr55Cu30Al10Ni5)99Nb1 bulk metallic glass

Non-isothermal crystallization kinetics of (Zr55Cu30Al10Ni5)99Nb1 bulk metallic glass (BMG) was studied by differential thermal analysis and differential scanning calorimetry. The crystallization pathway was changed by increasing the heating rate. The apparent activation energy at characteristic temperatures was calculated using Kissinger method. Local activation energy variations by crystallized volume fraction (α) (a.u. Ec(α)) was extracted using Ozawa-Flynn-Wall (OFW) method. Crystallization reaction function (f(α)) at different heating rates was extracted by means of Šesták-Berggren (SB) model.

Pyrolysis of post-methanated distillery effluent (PMDE) solid waste: Thermogravimetric degradation, kinetic and thermodynamic study with a circular bioeconomy approach

Post-methanated distillery effluent (PMDE) is a harmful dark brown to black color distillery effluent and is often released in open pond systems after anaerobic digestion by molasses-based distilleries. Due to the high standards imposed by Environmental Protection Acts, various methods of treating effluent were explored. However, pyrolysis showed excellent potential to treat it and recover energy. Hence, the present study explores the viability of producing energy from PMDE solid waste through pyrolysis. The reaction was performed at 900 °C with 20 °C min −1 heating rate in a fixed bed reactor, resulting in 36.12 wt% condensable volatiles, 22.6 wt% non-condensable gases, and 41.28 wt% solid biochar. The gas chromatographic (GC) analysis of the non-condensable gas revealed the presence of CO (17.83 vol%), H2 (8.10 vol%), and CH4 (4.30 vol%) in significant amounts, and C2H4, C2H6, C3H8, and C4H10 in minor quantities. Biochar obtained from the process has a microscopic surface area of 62.13 m2 g−1. A kinetic and thermodynamic study was performed using isoconversional methods to understand the reaction mechanism. Kinetic analysis showed the activation energy of PMDE solid waste pyrolysis to vary from 120 kJ mol −1 to 180 kJ mol −1 as conversion increases, and thermodynamic parameters (ΔH, ΔS, and ΔG) show the explanation for variation in activation energy. Additionally, the bio-circular economic approach of PMDE solid waste was presented.

Dual dynamic bonds approach for polyurethane recycling and self-healing of emulsified asphalt

To recycle polyurethane and extend the service life of polyurethane-modified emulsified asphalt, this study developed novel perspectives for a lower carbon-footprint and cleaner preparation of recyclable polyurethane (RWPU) and its modified emulsified asphalt (RPUA-x) by using self-emulsification and dual dynamic bonds. Particle dispersion and zeta potential tests reflected that the emulsions of RWPU and RPUA-x existed excellent dispersion and storage stability. Microscopic and thermal analyses indicated that RWPU possessed dynamic bonds and maintained thermal stability below 250 °C as anticipated. Concurrently, RWPU provided RPUA-x with a strong physical cross-linking network, and a homogeneous phase was observed in RPUA-x after drying. Self-healing and mechanical evaluation results revealed that the regeneration efficiencies of RWPU were 72.3 % (stress) and 100 % (strain), respectively, and the stress-strain healing efficiency of RPUA-x was >73 %. The energy dissipation performance and plastic damage principle of RWPU were investigated using cyclic tensile loading. The multiple self-healing mechanisms of RPUA-x were revealed through microexamination. Furthermore, the viscoelasticity of RPUA-x and variations in flow activation energy were determined based on Arrhenius fitting from dynamic shear rheometer tests. In conclusion, disulfide bonds and hydrogen bonds endow RWPU with remarkable regenerative properties and grant RPUA-x with both asphalt diffusion self-healing and dynamic reversible self-healing capabilities.

Thermo-kinetic analysis of pyrolysis of thermally pre-treated sewage sludge from the food industry

Due to the specific characteristics of sewage sludge from the food industry, including its high fat content, its treatment is quite complex. Therefore, in this study, the effect of the pre-treatment processes torrefaction (T) and hydrothermal carbonization (HTC) on the pyrolysis of industrial sewage sludge (SS) from the vegetable oil industry was investigated by thermogravimetric analysis. Kinetic and thermodynamic analysis was performed using the Kissinger-Akahira-Sunose (KAS), Flynn-Wall-Ozawa (FWO), and Friedman (FRI) iso-conversional kinetic models. In addition, the influence of water replacement by whey in the hydrothermal carbonization process was investigated on the subsequent pyrolysis kinetics.The activation energy (Eα) values for pyrolysis of industrial sewage sludge ranged from 49 to 372 kJ/mol. Pre-treatment (torrefaction, hydrothermal carbonization) of sewage sludge increases the activation energy significantly: the Eα values for torrefied (T-SS) and hydrothermally treated (HTC-SS) samples ranged from 177 to 689 kJ/mol and from 161 to 486 kJ/mol, respectively. The variations in activation energy and the generally lower activation energies for the HTC-SSW sample (158–445 kJ/mol) indicate that the use of whey in the HTC process affects the hydrochar properties and subsequent pyrolysis kinetics significantly. According to the results, the pre-treatment of the samples is reflected in better thermochemical properties and stability of the treated samples, as well as in the thermodynamic parameters of pyrolysis, since the pre-treated samples (especially the torrefied sample, T-SS) exhibited higher entropies and enthalpies and lower Gibbs free energies.

Study on the Bath Smelting Reduction Reaction and Mechanism of Iron Ore: A Review

Against the background of low global carbonization, blast furnace ironmaking technology with coking puts huge amounts of pressure on the global steel industry to save energy and reduce emissions due to its high pollution levels and high energy consumption. Bath smelting reduction technology is globally favored and studied by metallurgists as a non-blast furnace ironmaking technology that directly reduces iron ore into liquid metal without using coke as the raw material. The smelting reduction reaction of iron ore, which is the core reaction of the process, is greatly significant to its productivity and energy saving. Therefore, this paper focuses on the behavior and mechanism of iron ore’s smelting reduction. This work focuses on three key aspects of smelting reduction, namely, the thermal decomposition characteristics of iron ore during the smelting reduction, the smelting reduction mechanism of iron-ore particles, and the smelting reduction mechanism of FeO-bearing slag. The experimental study methods, reaction mechanisms, influencing factors, and kinetic behavior of the three are highlighted. In this work, the reaction mechanism of thermal iron-ore decomposition, iron-ore particle smelting reduction, and FeO-bearing slag smelting reduction on the three reactions were observed, providing a theoretical basis for how to select and optimize raw materials for the bath smelting reduction process. Moreover, the kinetic study clarifies the limiting steps of the reactions and provides guidance for an improvement in the reaction rate. However, certain blank points in previous studies need to be further explored, such as the differences in the research results of same factor, the large variation in reaction activation energy, and the coupling mechanism and inter-relatedness of the three key aspects’ reactions with each other.

Temperature Distribution and Thermal Criticality of Kinetics Exothermic Reactant in Concentric Cylinders Subject to Various Boundary Conditions

A study of the high-heat distribution of reacting species with approximation kinetics is essential in practical applications, for example, chemical synthesis, explosion safety and propulsion denotatives. As such, the temperature distribution and thermal criticality of an exothermic kinetics species in a concentric cylinder is the focus of this study. The chemistry of the pre-exponential factor, termination step, initiation rate and branch chain of the combustible reactant is investigated to study the system’s critical behaviour. The temperature is assumed not to be large; as such, the consumption of reactant species is ignored. A partition weighted residual semi-analytical approximate solution to heat propagation under boundary conditions, thermal ignition and branch chain for varying activation energies and chemical kinetics is discussed. The solution validation criteria for the approximate semi-analytical method and numerical method are established. This study ascertained the impact of boundary conditions on the explosion, and the effect of certain parameter changes on the heat distribution and thermal criticality was shown to be significant. Hence, the outcomes offer an understanding into the homogeneous species behaviour in a cylindrical geometry.