Parameters Of Thermal Decomposition Research Articles

Kinetic model of thermal decomposition of nitric acid solutions of hydrazine nitrate

The kinetic parameters of thermal decomposition of an aqueous solution containing 0.029 mass fractions of hydrazine nitrate and 0.44 mass fractions of nitric acid have been determined: onset temperature and specific thermal effect of exothermic reactions, activation energy, pre-exponential factor, reaction rate and order. Based on the data obtained, a mathematical model of thermal decomposition of nitric acid solutions of hydrazine nitrate has been proposed. It has been found that thermolysis of the solution has a multi-stage nature and can be described by a system of 5 equations of 1st and 2nd order. A comparison of two approaches to creating a mathematical model has been carried out: based on adiabatic calorimetry and differential scanning calorimetry data.

Kinetic parameters of thermal decomposition of biofuels and its oil-containing composites

The kinetic features of the decomposition of fuel pellets formed from birch phloem and its composites with the addition of oil-containing waste (OCW) were studied by methods of thermogravimetric analysis carried out in various atmospheric conditions. The characteristic temperature ranges of thermal decomposition of the materials from which pellets are formed were identified, the rates of mass loss and activation energy at the main stages of thermal decomposition were evaluated, and the combustion indices of composite compositions were determined to identify the possibility of using such compositions as alternative fuels. By evaluation of activation energies for each stage of sample decomposition, the limiting influence of certain stages on the process of thermal destruction was established.

Investigation of the Thermokinetic and Thermodynamic Parameters of Biodiesel and Associated Oil from Palm Kernel Oil During Thermal Degradation

ABSTRACT This study investigates the kinetic and thermodynamic parameters of the thermal degradation of biodiesel produced from low-grade palm kernel oil. In this work, biodiesel was produced through a two-step transesterification from a palm kernel oil having a free fatty acid content of 5.7%. The first step uses 25% methanol (wt% of palm kernel oil) and 1% sulfuric acid (wt% of palm kernel oil) to reduce the free fatty acids content to 0.3% within 30 min reaction time. In the second step, a methanol-to-oil molar ratio of 6:1 and 0.6% (wt% of palm kernel oil) of KOH yielded a palm kernel oil conversion of 96.96% after 30 min reaction time. The palm kernel biodiesel was analyzed using Fourier Transform Infrared spectroscopy, gas Chromatography tandem mass spectrometry, nuclear magnetic resonance spectroscopy (1H and13C), and thermogravimetric analysis. The thermal stability of palm kernel biodiesel was assessed through the kinetic and thermodynamic parameters of biodiesel thermal decomposition using isoconversional techniques. The Flynn-Wall-Ozawa, Kissinger-Akariha-Sunose, and Starink models were used to evaluate the kinetic parameters, while the Coats and Redfern technique was used to forecast the most probable mechanism of the palm kernel biodiesel thermal degradation. The average activation energies of 108.60 kJ mol−1, 107.75 kJ mol−1 and 95.77 kJ mol−1 using the Flynn-Wall-Ozawa, Kissinger-Akahira-Sunose, and Starink methods, respectively. FWO method best described palm kernel oil and biodiesel decomposition, with the highest R2 values of 0.94 for the oil and 0.93 for biodiesel The results obtained from the thermodynamic study (ΔH = 218.48 kJ.mol−1, ΔG = 200.05 kJ.mol−1 and ΔS = 27.10 J.mol−1.K−1) revealed that the biodiesel thermal degradation was an endothermic, non-spontaneous process governed by a three-dimensional diffusion reaction mechanism.

Effect of curative in hydroxyl-terminated polybutadiene-based binder system on characteristic properties and kinetics of polymer-based energetic composite

ABSTRACT A series of polymer-based energetic composites (PEC) comprising 90% (by wt.) of crystalline octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) filler and 10% (by wt.) of hydroxyl-terminated polybutadiene (HTPB)-based binder system cured with different curing agents were prepared by cast cured technique. The effects of HTPB-based binder cured with different curing agents on the characteristic properties were investigated through different analytical and instrument techniques. The chemical stability was studied through vacuum stability tester apparatus at 100°C for 40 h. The results show that all energetic composites are chemically stable and compatible with each other. The results indicate that there is considerable variation in the impact and friction sensitivity with varying of the curing agents in the HTPB-based binder system. Thermogravimetric (TG) and differential scanning calorimetry measurements show that the thermal stability does not depend on the curing agents used. The detonation study outcomes show that the detonation performance of the composites is quite different, depending on the types of the curing agents used. The kinetic parameters for thermal decomposition were studied through the TGA methods at multiple heating rates by using the kinetic Ozawa, Kissinger, and Kissinger–Akahira–Sunose (KAS) methods. The PEC/TDI, PEC/IPDI, PEC/MDI, and PEC/TMDI samples showed average activation energies of 236.5, 208.7, 192.8, and 250.3 kJ/mol, respectively. These values are consistent and comparable to those obtained from other kinetic methods. However, the activation energy varies with varying the curing agent used in HTPB-based binder system.

Thermodynamics and energy properties of the lowest eutectic mixture of TNBA/MTNP

In light of the challenges posed by the low density, diminished energy levels, and shrinkage holes in the loading arise of the current cast-cured explosive liquid vehicle, TNT, the investigation of low-melting eutectic materials as potential substitutes for TNT has emerged as a focal point of research. By employing the solvent-nonsolvent method, the lowest eutectic mixture of TNBA(2,4,6-trinitro-3-bromoanisole)/MTNP(1-methyl-3,4,5-trinitropyrazole) was synthesized, distinguished by a moderate melting point and markedly elevated energy levels as compared to TNT. Comprehensive SEM, EDS, IR, XRD, and XPS analyses were conducted on the lowest eutectic mixture, substantiating the absence of any chemical interaction between TNBA and MTNP and affirming their exceptional compatibility. Moreover, an exploration into the thermal decomposition behavior and mechanism of the lowest eutectic mixture was undertaken, its mechanical sensitivity was tested, and its detonation performance was evaluated by EXPLO-5 software. The thermal decomposition parameters of the lowest eutectic mixture closely paralleled those of the precursor materials, with the thermal decomposition kinetics model function being identified as the Jander function. The impact sensitivity of the lowest eutectic was 48.1 cm and the friction sensitivity was 12%. Furthermore, the density of the lowest eutectic mixture surpassed 1.8 g/cm3, and its detonation velocity approached 8000 m/s, markedly surpassing the explosive performance of TNT.

Kinetic Parameters of Thermal Decomposition of Biofuels and Its Oil-Containing Composites

Kinetic Parameters of Thermal Decomposition of Biofuels and Its Oil-Containing Composites

Investigating the catalytic effect of nanoferrites additives on the thermal decomposition of ammonium perchlorate and burning rate modification of the composite solid propellants

The co-precipitation method was used to synthesize nanosize copper ferrite (CuF) and cobalt-copper-nickel ferrite (CoCuNiF). Physico-chemical characterization of material was done using powder X-ray diffraction, Raman, UV–Vis, and atomic force microscopy (AFM). The effect of 1 % by mass additives on the thermal decomposition and kinetics parameters of ammonium perchlorate (AP) was investigated using non-isothermal isoconversional methods such as Flynn wall Ozawa (FWO), Kissinger Akahira Sunose (KAS), and Starink. The burning rate enhancement and ignition delay study were also investigated. The catalysts can decrease the activation energy of AP by 48 % along with increasing the burning rate of the corresponding composite materials. Both the catalysts can be successfully used for enhancing the burning performance of propellants and hence can be used for rocket and missile propulsions.

Microstructural and thermal properties of coal measure sandstone subjected to high temperatures

To study the microscopic structure, thermal and mechanical properties of sandstones under the influence of temperature, coal measure sandstones from Southwest China are adopted as the research object to carry out high-temperature tests at 25 °C–1000 °C. The microscopic images of sandstone after thermal treatment are obtained by means of polarizing microscopy and scanning electron microscopy (SEM). Based on thermogravimetric (TG) analysis and differential scanning calorimetric (DSC) analysis, the model function of coal measure sandstone is explored through thermal analysis kinetics (TAK) theory, and the kinetic parameters of thermal decomposition and the thermal decomposition reaction rate of rock are studied. Through the uniaxial compression experiments, the stress‒strain curves and strength characteristics of sandstone under the influence of temperature are obtained. The results show that the temperature has a significant effect on the microstructure, mineral composition and mechanical properties of sandstone. In particular, when the temperature exceeds 400 °C, the thermal fracture phenomenon of rock is obvious, the activity of activated molecules is significantly enhanced, and the kinetic phenomenon of the thermal decomposition reaction of rock appears rapidly. The mechanical properties of rock are weakened under the influence of rock thermal fracture and mineral thermal decomposition. These research results can provide a reference for the analysis of surrounding rock stability and the control of disasters caused by thermal damage in areas such as underground coal gasification (UCG) channels and rock masses subjected to mine fires.

A study on the preparation of V2O5 from NH4V3O8 based on thermal decomposition including the thermal decomposition temperature effect, mechanism and kinetics

This study extensively investigated the thermal decomposition process of NH4V3O8, examining how varying temperatures affect the physicochemical properties of the products, as well as exploring the mechanism and kinetics of the process. Through XRD and SEM analysis, the study identified the phase compositions, crystal structures, and micromorphology of the thermal decomposition products. It also systematically investigated the effects of temperature on particle size and specific surface area, identified the lowest thermal decomposition temperature, and proposed the reaction equations. Additionally, by employing FT-IR analysis and DFT calculation, the study revealed the molecular-level thermal decomposition mechanism of NH4V3O8. Finally, the study calculated the kinetic parameters of NH4V3O8 thermal decomposition using the Kissinger and Kissinger-Crane methods and established the rate equation. These findings not only provide practical guidance but also serve as theoretical references for the thermal decomposition of other metal ammonium salts.

Kinetic of Oil Sludge Thermolysis Process in Presence of Nickel, Cobalt and Iron-Supported Microsilicate

Abstract The article is devoted to the experimental determination of thermokinetic parameters of oil sludge thermal degradation using the model-free Ozawa-Flynn-Wall method in the presence of a nanocatalyst (nickel, cobalt and iron-supported microsilicate) by calculating Arrhenius kinetic parameters (activation energy and pre-exponential factor). The phase composition of the reflex microsilicate was established – 4.12; 2.51 Å – SiO2, nickel-supported microsilicate reflexes: 2.09; 1.48 Å – NiO, reflexes: 4.25 Å – SiO2 and acid numbers of microsilicate – 64 μmol/g of prepared nanocatalysts. Using the method of Brunauer, Emmett and Teller, the specific surface area of the microsilicate was established – 18.3 ± 0.3 m2/g, the microsilicate with nickel applied – 20.9 ± 0.2 m2/g and the adsorption isotherm of the prepared nanocatalysts (microsilicate with nickel, cobalt and iron). Thermokinetic parameters of thermal decomposition of oil sludge without a catalyst and with a catalyst at an increment of 0.9 are 99.0 and 93.3 kJ/mol nickel-supported microsilicate, 51.9 kJ/mol cobalt-supported microsilicate, 111.3 kJ/mol iron-supported microsilicate and non-metal-supported microsilicate 173.7 kJ/mol, respectively. The study of the kinetic parameters of pyrolysis of oil sludge using various catalysts makes it possible to assess their influence on the process of decomposition of organic components. The results of the experiments showed that the use of catalysts significantly affects the destruction of oil sludge. Dynamic thermal analysis at different heating rates studied the dynamics of oil sludge decomposition. The study of the effect of catalysts on the kinetic parameters of oil sludge pyrolysis is an important step in the development of new methods for the disposal of petroleum products and the reduction of their negative impact on the environment. The obtained experimental data on thermal degradation kinetics of oil sludge will find application in designing a reactor for the process of destructive hydrogenation of heavy hydrocarbon raw materials.

A study on the preparation of Cr2O3 from (NH4)2Cr2O7 based on thermal decomposition including the thermal decomposition temperature effect, mechanism and kinetics

In this study, the thermal decomposition process of (NH4)2Cr2O7, including the effect of thermal decomposition temperature on the physicochemical properties of products, thermal decomposition mechanism, and kinetics, was studied in detail. The phase compositions, crystal structures, and micromorphology of thermal decomposition products were determined based on XRD and SEM analysis. The effect of thermal decomposition temperature on particle size, specific surface area, and chromaticity was investigated systematically. The lowest thermal decomposition temperature was determined, and the reaction equations were conjectured. The thermal decomposition mechanism of (NH4)2Cr2O7 was further revealed at the molecular level using FT-IR analysis and DFT calculation. At last, Kissinger and Kissinger-Crane methods calculated the kinetic parameters of (NH4)2Cr2O7 thermal decomposition, and the rate equation was established.

Enhancing risk/safety management of HAN-based liquid propellant as a green space propulsion fuel: A study of its hazardous characteristics

The knowledge of hazard classification of hydroxylammonium nitrate (HAN)-based liquid propellant is an essential subject in prevention of safe and transportation accidents. To improve hazard classification of the propellant, various tests were conducted on both material sample and packaged sample. Differential scanning calorimeter was utilized to study thermal decomposition parameters, resulting in the determination of high values for both thermal decomposition and explosion temperatures. Koenen and EIDS gap tests were used to evaluate the heat response under high confinement and the sensitivity of shock, respectively. The results indicated that the propellant was insensitive to shock wave, with a limiting diameter of 3.0 mm. The external fire test was conducted to elucidate the explosion characteristics of the packaged propellant. Pictorial information and temperature data were recorded using high-speed camera and infrared imager. The results revealed that a mass explosion occurred during the fire process. The combination of the perforated witness screen, long-range metallic projections and high-value heat flux led to the classification of the packaged HAN-based liquid propellant as Class 1.1 C, more stringent than the traditional Class 1.3 C. The study is expected to offer valuable insights for the safety of development, preservation, and conveyance of HAN-based liquid propellant.

Технология извлечения полезных компонентов из горючих сланцев месторождения Актау

This paper describes technologies for processing of oil shales and determines parameters of thermal decomposition without oxygen access (pyrolysis) and hydrometallurgical methods for extracting useful components. The following methods are presented: leaching to extract valuable components into a sulfuric acid solution, and selective extraction to ion-exchange resins by sorption of valuable components of vanadium and molybdenum. The presented methods are not implemented on an industrial scale, since there is no oil shale processing in the Republic. Perspective technological schemes of oil shale ash processing are analyzed. The process involves the addition of sodium chloride to the process of thermal decomposition without access to oxygen (pyrolysis). The resulting ash is leached in vats with sulfuric acid 160 g/l, at room temperature, T : W = 1 : 5, duration 60 minutes. The resulting metal-bearing sulfuric acid solution is filtered and sent to sorption and precipitation. Extraction of vanadium and molybdenum into solution is more than 60–70 %. It should be noted that with an increase in the consumption of sulfuric acid over 160 g/l, the concentration of metals in the productive solution does not increase. The ion-exchange resins of the English company PUROLITE were used to extract metals from the productive solutions of leaching of oil shale ash from the Aktau deposit: for the extraction of molybdenum — A-100 Mo grade, and vanadium — A-109 grade.

A comparison between two kinetic models for the pyrolysis and gasification of woody wastes under a carbon dioxide atmosphere

A pine forest residue, a pine wood industrial waste and their mixture were pyrolyzed and subsequently gasified under a carbon dioxide atmosphere up to 1000 °C in a thermal analysis system. Thermal decomposition parameters, such as reactivity, reaction rate and syngas yield, were determined and the influence of CaO catalyst was examined. Two kinetic models, independent parallel reactions model (IPR) and distributed activation energy model (DAEM), were developed in Matlab® code for the kinetic analysis of the processes. Three first order reactions were found to accurately describe the pyrolysis process by both models, with deviation values between 1.3 % and 2.9 %. Activation energy values varied between 26 kJ/mol and 201 kJ/mol. One pseudo-component was necessary to describe successfully the gasification process by application of both models, with deviation values 2.4–6.5 %. Activation energy values ranged between 192 kJ/mol and 345 kJ.mol. The IPR model was found to be more practical to employ.

Synthesis, Thermogravimetric Analysis, and Kinetic Study of Poly-N-Isopropylacrylamide with Varied Initiator Content.

The thermal decomposition and kinetic parameters of four polymers, PN-1, PN-05, PN-01, and PN-005, were determined by thermogravimetry (TGA/DTG) under non-isothermal conditions. N-isopropylacrylamide (NIPA)-based polymers were synthesized by the surfactant-free precipitation polymerization (SFPP) with different concentrations of the anionic initiator potassium persulphate (KPS). Thermogravimetric experiments were carried out in the temperature range of 25-700 °C at four heating rates, 5, 10, 15, and 20 °C min-1, under a nitrogen atmosphere. Poly NIPA (PNIPA) showed three stages of mass loss during the degradation process. The thermal stability of the test material was determined. Activation energy values were estimated using Ozawa, Kissinger, Flynn-Wall-Ozawa (FWO), Kissinger-Akahira-Sunose (KAS), and Friedman (FD) methods.

Coupling effect on the thermal hazard assessment of hazardous chemical materials via calorimetric technologies and simulation approaches

The coupling effect of heat absorption and release exists in the thermal decomposition of a few chemical materials. However, the impact of the above coupling on thermal hazard assessment is not considered in the literature studies. In this work, nitroguanidine (NQ) and 1,3,5-trinitro-1,3,5-triazine (RDX) are selected as representative materials to explore the influence of the coupling effect on the thermal hazard assessment of chemical materials. The linear heating experiments of NQ and RDX are carried out by a microcalorimeter and synchronous thermal analyser. The thermal decomposition curves are decoupled by advanced thermokinetics software. The thermal decomposition and kinetic parameters before and after decoupling are calculated. The results of TG experiment show that both NQ and RDX began to lose mass during the endothermic stage. The endothermic melting and exothermic decomposition of NQ and RDX are coupled within this stage. The coupling effect has different degrees of influence on its initial decomposition temperature and safety parameters. Compared with the parameters in the coupling state, the initial decomposition temperature and adiabatic induction period after decoupling decrease. The self-accelerating decomposition temperature increases, and internal thermal runaway time decreases. In the thermal hazard assessment of chemical materials with coupling effects, the calculated parameters after decoupling should be taken as an important safety index.

Synthesis, Characterization, Thermal Behavior and Biological Properties of Zn (II) Schiff Base Complexes

In this research, N, N`-bis ((E)-3-(4-dimethylamine) phenyl allylidene)-phenylen-1,2-diamine as a bidentate Schiff base ligand, was synthesized in ethanol and purified and then was identified by physical and spectral methods. Using this ligand, compounds with the general formula of ZnLX2 in which X is Clˉ, Brˉ, Iˉ, N3ˉ, SCNˉ and/or NO3ˉ. Different techniques such as FT-IR, UV-Vis, 1H-NMR, thermal analysis (TG, DTA, DTG), melting point and molar conductivity were used for characterization of the coordination compounds. The IR spectrum of the ligand shows the group (C=N) vibration frequency at 1604 cm-1 as main peak. However, the relevant frequency changed after complex formation which indicates coordination of the Schiff base ligand to the Zn metal ion. The data obtained from the UV-Vis spectra and the 1H-NMR of the ligand and its coordination compounds confirm their synthesis. Ultimately thermal behavior of the ligand and its metal compounds in the temperature range of 20-900˚C was studied and their decomposition steps were evaluated along with some thermo-kinetic parameters of thermal decomposition of the complexes in each decomposition step.

Studies on Ablative Performance of Silicone Low-Density Ablative Material

In the present studies, silicon based low-density ablative material has been studied for its ablative performance to protect flight hardware from temperature raises due to aerodynamic forces for a longer duration. The oxyacetylene flame test estimates ablative properties at 100–120 W/m2 heat flux. The time duration for the flame test is taken 200 s. The material shows low mass and linear ablation rate with high ablative effectiveness. The degradation kinetics of silicon ablator is studied by Thermo Gravimetric Analysis (TGA) method. Non-isothermal TGA is performed in the temperature range of 30 °C to 900 °C at various heating rates, viz. 5, 10, 15, and 20 °C/ min. Knowledge of the kinetic parameters of thermal decomposition is used to predict the degradation kinetics of the material at high heating rates, which the ablator faces during aerospace applications. During ablation, the silicone ablative material consists of a virgin zone, reaction zone, and char zone. These are explained by kinetic parameters determined with the help of free software called Kinetic Calculation.

Catalytic performance of nano-sized cobalt copper ferrite on thermal decomposition of ammonium nitrate

Ammonium nitrate (AN) is being explored as a high energetic oxidizer in propellants. The utilization of pure AN in propellants suffers from a low burning rate. To improve the burning rate, it is important to improve the thermal decomposition characteristics of AN to fasten its thermal decomposition. The effect of CoCuFe2O4 additive was explored to improve the thermos-kinetic parameters of AN's thermal decomposition. Coprecipitation was used to synthesize nanocrystalline CoCuFe2O4. The thermodynamic and kinetic parameters of decomposition of AN: CoCuFe2O4 were investigated using TG-DSC-DTA analysis at 5, 10, and 15 °C min−1. The thermodynamic and kinetic studies suggest that the thermal decomposition of AN+CoCuFe2O4 was more favorable than AN. The decomposition of AN+CoCuFe2O4 occurs at a lower 10 °C lower temperature with ∼44 % decrement in the activation energy and decreased pre-exponential factor. The faster decomposition at a lower temperature was obtained for AN+CoCuFe2O4 composition. Nano-sized particles with efficient optical and polarizable properties made this ferrite material easily separable and eco-friendly for the preparation of a chemical propulsion system based on AN. The AN+CoCuFe2O4 propulsion mixture can be utilized in place of pure AN for better thermal performance in a propellant system.•CoCuFe2O4 was able to influence the thermal decomposition parameters of ammonium nitrate (AN).•AN+CoCuFe2O4 decomposes at lower activation energy with a faster decomposition than pure AN.•Thermodynamics suggest favorable decomposition of AN+CoCuFe2O4 than pure AN.

A new flame retardant and its effect on the asphalt mixture

To alleviate the problem of decomposition products of organic flame retardants with toxic, inorganic flame retardants were used to prepare flame retardant modified asphalt (FRA), but the traditional inorganic flame retardants have a significant flame retardancy only with a high dosage, and too high dosage would bring serious adverse effects on the pavement performance of asphalt mixture. For this, to avoid the side effects of inorganic flame retardants, a compound flame retardant was developed by orthogonal experiment method to alleviate the problem of high dosage of inorganic flame retardants, and to have a relatively significant flame retardancy. The flame retardancy was studied by conventional performance test, separation test, rotational viscosity (RV) test, dynamic shear rheology (DSR) test, limiting oxygen index (LOI) test, thermogravimetry (TG) test, pavement performance test, and combustion test. The results show that with the addition of self-developed flame retardant (WZRJ-I), the PI of FRA was increased by 23.4∼40.4 % compared with virgin asphalt, the LOI was increased by 24.7∼46 %, the rutting factor was increased by 12.6∼27.9 %, the thermal decomposition parameters were significantly improved at all stages, the burning time was reduced by 39 s∼53 s, the mass loss was reduced by 11.9∼15.4 %, which indicated that the addition of WZRJ-I was conducive to improve the flame retardancy and high temperature performance. Finally, the prediction equation model of combustion performance index and burning time of asphalt mixture was established, and the effect of burning time on the residual pavement performance of asphalt mixture was quantitatively analyzed.