Study Of Thermal Decomposition Research Articles

Thermal decomposition study of 1,3-dioxolane as a representative of battery solvent

As industrial compounds and organic solvent, 1,3-dioxolane (C3H6O2) is used in lithium-ion batteries arousing extensive interest. The pyrolysis of C3H6O2 at 150 torr pressure was conducted in the temperature range of 743-1013K. In order to quantify the major products, experimental measurements of the photoionization cross-section (PICS) and photoionization efficiency (PIE) for C3H6O2 were carried out by using synchrotron radiation photoionization mass spectrometry (SR-PIMS). Twenty-three intermediates were detected in pyrolysis of C3H6O2 including the newly observed ketene, acetaldehyde, ethenol, ethanol, dimethyl ether, diacetylene and 2-propen-1-ol which played important roles in developing mechanism. The H-abstraction of C3H6O2 by H, CH3 and OH radicals were studied via high level ab initio calculations. EStokTP code was used to find and calculate optimal geometries, vibration frequencies and intrinsic reaction coordinate (IRC) at the theory level of M06-2X/6-311+G(d,p). Conventional transition state theory (TST) was used and Rice-Ramsperger-Kassel-Marcus/Master Equation (RRKM/ME) was solved to obtain rate coefficients. For H-abstraction by H and CH3, the rates are increasing versus temperature, and rates of H-abstraction by OH show different tendency. These rate parameters were used to update the model of C3H6O2, which could well predict the ignition delay times (IDTs) in shock tube and oxidation data in jet stirred reactor (JSR) from literature. For the pyrolysis, H-abstraction reactions by H, CH3 and OH and unimolecular reactions contribute to solvent decay. Detailed pathways of C3H6O2 decomposition were also given and analyzed through this experiment and previous literature. The findings, including the experimental data and the calculations will assist to better understand pyrolysis characteristics of C3H6O2 as well.

Thermal decomposition study of 4-methyloxybenzyl-glycoside by TG/DTA and on-line pyrolysis-photoionization mass spectrometry

A flavor precursor of 4-methyloxybenzyl-2, 3, 4, 6-tetra-O-acetyl-β-d-glucopyranoside (MBGL) was synthesized via a modified Koenigs–Knorr reaction. The thermal decomposition behaviour and pyrolysis intermediate products of the glycoside were studied by simultaneous thermogravimetric/differential thermal analysis (TG/DTA) and synchrotron vacuum ultraviolet (VUV) photoionization mass spectrometry (PIMS). TG/DTA results showed that the largest mass loss rate appeared at a Tp of 246.7 °C. PIMS was used to identify the pyrolysis products of MBGL at 300 °C, 500 °C and 700 °C, respectively. The experimental apparatus had some advantages in real-time analysis and fewer secondary reactions. Some important pyrolysis intermediates, such as the ions of the 4-methyloxybenzyl group at m/z 121 and the glycone moiety at m/z 347, were detected by PIMS. The results indicate that the MBGL was probably showed a different pyrolysis way compared with the other glycosides. This work reports a useful application of synchrotron VUV PIMS in a thermal decomposition study of glycoside flavor precursors.

Studies of thermal decomposition of poly(vinyl chloride) composition with cadmium yellow and stearic acid

The article presents research on the thermal decomposition of individual ingredients and compositions that are physical mixtures of emulsion poly(vinyl chloride) (PVC), cadmium yellow, and stearic acid. The results of the tests were TG, DTA, and DTG graphs. From their course, the initial decomposition temperatures, maximum decomposition rate, and final temperatures were determined, and changes in the mass of samples and the values of thermal effects were calculated. The influence of pigment and stearic acid on the thermal decomposition of PVC was investigated. Cadmium yellow, modified in an alkaline medium and containing hydroxyl groups, was also used for the tests. It was found that the presence of both pigment and stearic acid had a retarding effect on the initiation of thermal decomposition of PVC. The addition of CdS modified in an alkaline environment had a more or less similar effect on the initial decomposition temperature of PVC. Depending on the composition of the polymer and the value of the final temperature, different values of thermal effects and the amount of products formed were indicated.

Thermal decomposition study of carbon fiber-reinforced polyphenylene sulfide at high heating rates met under fire exposure

Thermal decomposition study of carbon fiber-reinforced polyphenylene sulfide at high heating rates met under fire exposure

Co (II), Ni (II), and Cu (II) ternary complexes with 2,6‐pyridinedicarboxylic acid: Thermal decomposition, DNA interaction, and biological activity studies

Three novel ternary complexes [MII (PDA)(o‐phen)(H2O)] (MII = CoII, NiII, and CuII) were synthesized using 2,6‐pyridinedicarboxylicacid as a primary ligand and 1,10‐phenanthroline(o‐phen) as the auxiliary ligand and analyzed by FT‐IR, mass, UV–Vis, thermogravimetry analysis, and conductivity measurement data. Based on electronic spectral measurements, all three of the metal complexes were found to have octahedral stereochemistry. The way metal complexes interact with ct‐DNA was studied using various methods including absorption spectroscopy, fluorescence spectroscopy, and viscosity measurements. UV–Vis absorption technique has been used to explore the binding characteristics of M (II) complexes with ct‐DNA. The complexes bind to DNA via groove mode of binding, according to the spectral data. The salt‐dependent binding of ternary metal complexes to ct‐DNA has been studied by UV–Vis spectrophotometric titration experiment. Furthermore, gel electrophoresis is used to examine how the metal complexes interacted with the pBR322 DNA. The outcomes showed that these compounds can function as efficient DNA cleaving agents. Studies on the complexes' in vitro antibacterial activity demonstrated their importance and good antimicrobial activity at three distinct concentrations (50, 75, and 100 g/mL).

Nanoarchitectonics of CdFe2O4 nanoparticles with different morphologies synthesized using a thermal decomposition approach and studies of their peroxidase-like activity

In the current study, morphologically different CdFe2O4 nanoparticles (NPs) have been synthesized by a facile thermal decomposition approach using Cd–Fe glycolates as precursors.

Synthesis of ZnO–Ag Nanocomposites by Thermal Decomposition Method and Studies on their Antibacterial Activity Against E. coli and S. aureus

Synthesis of ZnO–Ag Nanocomposites by Thermal Decomposition Method and Studies on their Antibacterial Activity Against E. coli and S. aureus

Thermal Processing of Solid Vegetable Waste by Slow Conductive Pyrolysis

Pilot plants were developed to analyze heat and mass exchanges during the thermal decomposition of ligninocellulose. Methods of experimental research to determine the properties of thermal decomposition products were presented. Studies of thermal decomposition of plant raw materials for classical and high-temperature modes of slow pyrolysis were carried out. The pore structure of the obtained carbonate samples was studied. Optimal modes of slow conductive pyrolysis of vegetable raw materials were proposed. The paper presents the variant of industrial pyrolysis of plant waste into activated carbon.

Study of Thermal Decomposition of Layered Double-Magnesium Aluminum Hydroxide

Study of Thermal Decomposition of Layered Double-Magnesium Aluminum Hydroxide

Study of thermal decomposition of microalgae biomass pretreated by acetylation for biofuel production

Study of thermal decomposition of microalgae biomass pretreated by acetylation for biofuel production

The “Periodic Table” of 1-methylbenzotriazole: Zinc(II) Complexes

In an attempt to fill in the empty Zn position in the “Periodic Table” of 1-methylbenzotriazole (Mebta), reactions between Zn(II) sources and this ligand were carried out. The detailed synthetic studies provided access to complexes [ZnX2(Mebta)2] (X = Cl, 1; X = Br, 3; X = I, 4), (MebtaH)2[ZnCl4] (2), tet-[Zn(NO3)2(Mebta)2] (5), oct-[Zn(NO3)2(Mebta)2] (6), and [Zn(Mebta)4](Y)2 [Y = ClO4, 7; Y = PF6, 8]. Solid-state thermal decomposition of 2 leads to 1 in quantitative yield. The structures of 3, 4, 5, 6, and 7 were determined by single-crystal crystallography. The structures of the remaining complexes were proposed based on spectroscopic evidence. In all compounds, Mebta behaves as monodentate ligand using the nitrogen of the position 3 as donor. Complexes 1–4, 7, and 8 are tetrahedral. Complexes 5 and 6 are isostoichiometric and their preparation in pure forms depends on the reaction conditions; in the former the ZnII atom has a tetrahedral geometry, whereas in the latter the metal ion is octahedral. This case of rare isomerism arises from the monodentate (in 5) vs. bidentate (in 6) coordination of the nitrato groups. Extensive π–π stacking interactions and non-classical H bonds build interesting 3D architectures in the structurally characterized complexes. The compounds were characterized by IR, far-IR, and Raman spectroscopies in the solid state, and the data were interpreted in terms of the structures (known or proposed) of the complexes and the coordination modes of the organic and inorganic ligands involved. The solid-state structures of the complexes are not retained in solution, as proven by NMR (1H, 13C[1H]) spectroscopy and molar conductivity data. The thermal decomposition study of 1 and 3 leads to stable intermediates with 1:1 stoichiometry, i.e., ZnX2(Mebta). Based on far-IR spectra, polymeric tetrahedral structures are possible with simultaneous presence of terminal and bridging X− groups. Liquid-phase ab initio (MP2) and gas-phase DFT calculations, performed on Mebta and the nitrato complexes, respectively, shed light on the tendency of Mebta for N3-coordination, and the existence and relative stabilities of 5 and 6.

Experimental and theoretical studies on the kinetics of thermal decomposition and decomposition mechanism of CF3I in oxidizing environments

CF3I, as a novel “Halon” replacement fire-extinguishing agent, has the characteristics of low fire-extinguishing concentration, high efficiency, and safety. However, there are still some gaps in its thermal decomposition studies when it is released into the high-temperature fire, so the thermal decomposition of CF3I in oxidizing environments was studied to simulate its diffusive decomposition. The decomposition of CF3I was demonstrated to be accelerated by O2 through experiments in the temperature range of 100°C-800°C in air and N2 atmosphere. The effects of initial concentration, temperature, and residence time on the decomposition rate of CF3I and decomposition characteristics were investigated by tube furnace simulation. The kinetics of thermal decomposition was calculated using the Arrhenius equation in which activation energy Ea is 15.18 kJ/mol and pre-exponential factor (A) is 13.87s−1. Additionally, the thermal decomposition products were examined by GC-MS and FTIR. The experimental results showed that the pyrolysis gas products were mainly CF4, C2F6, and CF2O. Using quantum chemistry and density flooding theory (DFT) calculations, it was concluded that the main decomposition pathway was the reaction of CF3I with singlet oxygen. The reaction pathway of the thermal decomposition of CF3I under a high-temperature fire oxidation environment was proposed based on the products.

Analysis of methane pyrolysis experiments at high pressure using available reactor models

Most batch reactor methane thermal decomposition (MTD) studies have focused on sub-atmospheric pressures. In this study, MTD experiments were performed between 892 K and 1292 K and 4 atm inside a quasi-isothermal quartz batch reactor at residence times ranging from 0 to 300 s. At a given temperature, elevated pressure resulted in higher methane conversion compared with the sub-atmospheric conditions. A zero-dimensional, closed, isochoric, homogeneous gas-phase model was used to compare numerical predictions from available reaction mechanisms in literature to experimental data. It was found that most models accurately predict conversion at low pressure and high temperature and at high pressure and high temperature, but did not accurately predict methane, hydrogen, and intermediate species mole fractions at 4 atm and either 892 K or 1093 K. A reaction path analysis showed the reactions responsible for the delay in hydrogen formation at elevated pressure are 2CH3(+M)⟺ C2H6, C2H6 ＋ CH3⟺ C2H5 ＋ CH4, C2H6 ＋ H ⟺ C2H5 ＋ H2 and C2H5(+M)⟺ C2H4 ＋ H, where M is the collision partner. A gas-phase model accounting for the solid carbon shows that the observed discrepancy is not due to the unavailability of the carbon formation model but to slower reaction kinetics, especially at lower temperatures. The experimental data presented can be used to obtain a methane pyrolysis reaction mechanism suitable for high pressure conditions.

Influence of Titanium Dioxide Grain Size on Phasic Composition and Lysozyme Adsorption of Hydroxyapatite and Titanium Dioxide Composite Powders—A Thermal Decomposition Study by XRD and SEM Analysis

AbstractBiomedical applications make high demands on the development of novel bioactive materials, which are often based on functionalized calcium phosphates (CaPs). In this study, pure nanoscaled hydroxyapatite (HAp) and modified HAp with titanium dioxide (TiO2) with both nano‐ and microparticles are successfully synthesized from the reactants calcium hydroxide and orthophosphoric acid in a wet chemistry reaction. The obtained powders are sintered in a temperature range of 750 °C–1400 °C to study their thermal decomposition behavior. The phase composition and the surface morphology are characterized using X‐ray diffraction, scanning electron microscopy, and energy dispersive X‐ray spectroscopy with element mapping. Lysozyme adsorption experiments reveal significantly higher adsorption on the samples modified with nanoparticles. Sintered samples modified with both TiO2particle sizes show HAp decomposition to β‐tricalcium phosphate (β‐TCP) as well as the formation of perovskite (CaTiO3) in different portions depending on the TiO2particle size. TiO2nanoparticles support anatase to rutile transformation at lower temperatures than TiO2microparticles. The results show that the examined HAp/TiO2composites may serve as a starter material for tailormade biomaterials with specific composition by variation of the sintering temperature and the TiO2particle size.

Experimental and kinetic study of N2O thermal decomposition in pressurized oxy-combustion

Pressurized oxy-combustion is regarded as a promising carbon capture technology for mitigating global warming. In addition, N2O is a significant greenhouse gas in pressurized oxy-combustion at moderate temperatures, with a Global Warming Potential 310 times that of CO2. It is important to study the formation and control of N2O in pressurized oxy-combustion. In this paper, the effects of CO2 atmosphere, pressure, temperature, residence time, and O2 concentration on N2O decomposition were investigated in a pressurized plug flow reactor. The results show that CO2 atmosphere significantly promotes N2O decomposition compared to N2 atmosphere. Increasing temperature accelerates the decomposition of N2O, with 1023–1223 K being the main decomposition temperature range. The decomposition efficiency of N2O increases with increasing pressure, while its increase becomes slow at above 5 bar. N2O decomposition efficiency in CO2 atmosphere decreases slightly as O2 concentration increases. The experimental results were compared to the kinetic modeling results calculated using GRI3.0 and GLA2018 mechanism, respectively. The modeling results show that GRI3.0 mechanism accurately predicts the decomposition of N2O at 1 bar while overestimates the decomposition at elevated pressures, while GLA2018 mechanism significantly underestimates the decomposition at all tested pressures. Further Rate-of-production analysis shows that the main reaction of N2O decomposition is N2O(+M) = N2 + O + M, which becomes the dominant reaction especially at elevated pressures. An enhanced third-body efficiency of 3 for CO2 was incorporated into the reaction N2O(+M) = N2 + O(+M) in GLA2018, which could predict the decomposition of N2O at elevated pressure accurately. The above results indicate that the decomposition of N2O is significantly enhanced in pressurized oxy-combustion.

Thermal decomposition study of ammonium nitrate in the presence of nickel‑zinc ferrite additive

Thermal decomposition study of ammonium nitrate in the presence of nickel‑zinc ferrite additive

Evaporation and thermal decomposition of 1-ethyl-3-methylimidazolium chloride

The use of ionic liquids (IL) at elevated temperatures has revealed interest in the study of evaporation and thermal decomposition (thermolysis) processes that determine the thermal stability of IL. In this work the evaporation of 1-ethyl-3-methyl-imidazolium chloride ([EtMIm][Cl]), which is accompanied by the significant thermal decomposition, was studied by the Knudsen cell mass spectrometry. The composition of gas phase over [EtMIm][Cl] and its change in time were established in the temperature range of 403–449 K. The saturated vapor pressures, vaporization enthalpy and rate constants of thermolysis reactions were determined. The equilibrium and rate constants for gas-phase thermolysis reactions of [EtMIm][Cl] were calculated by the quantum chemical methods. Based on the results of experiments and calculations, the processes responsible for mass loss – thermolysis and evaporation – were quantitatively described.

Thermal decomposition characteristics and study of the reaction kinetics of tea-waste

This study aimed to investigate waste-tea’s pyrolysis kinetics and thermodynamics to assess its potential for thermochemical processes. In this study, three primary samples of tea-waste are prepared for investigation: raw, torrefied at 200 °C, and torrefied at 600 °C. Under a nitrogen environment, thermogravimetric analyses (TGA) were conducted at seven heating rates (10, 15, 20, 25, 30, 35, and 40 °C/min) to investigate the effect of heating rates on the kinetic parameters at temperatures ranging from 27 to 1000 °C. Using seven heating rates was beneficial to take advantage of multiple heating rates techniques alongside single heating rate techniques. These heating rates were combined, forming four heating rate groups (HRG). The pyrolysis kinetic parameters are determined using two model-fit-methods, direct Arrhenius and Coats-Redfern methods, and two model-free methods, Flynn-Wall-Ozawa (FWO) and Kissinger-Akahira-Sunose (KAS) methods. Thermodynamic data comprising ΔH, ΔG, and ΔS are addressed. The X-ray fluorescence (XRF) and Fourier transform infrared (FTIR) spectrum are used to assess the presence of natural minerals in tea-waste. The results indicated that the tea-waste material has the potential to produce syngas. The torrefaction process at 600 °C shows a 53% increase in the energy content compared to the raw biomass. The Coats-Redfern is shown to be more reliable than the direct Arrhenius method. The activation energy (Ea) witnesses rising with the heating rate (β) from Ea = 55.27 kJ mol−1 at β = 10 °C min−1 to 60.04 kJ mol−1 at β = 40 °C min−1 for raw tea-waste using Coats-Redfern method. For model-free approaches, the minimum activation energy values of the raw tea-waste samples are 82 kJ/mol for FWO and 78 kJ/mol for KAS, whereas the peak values are 420 kJ/mol for KAS and 411 kJ/mol for FWO. A comparison of the effect of heating rate groups for FWO method in raw material case indicated that HRG1 has the maximum activation energy average value. The resulting values of HRG1, HRG2, HRG3, and HRG4 were 269 kJ/mol, 145 kJ/mol, 174 kJ/mol, and 202 kJ/mol, respectively.

Kinetics modeling & comparative examine on thermal degradation of alkali treated Crotalaria juncea fiber using model fitting method

This study aims at investigating pyrolysis kinetics of untreated and alkali-treated Crotalaria juncea (sunnhemp) fiber by widely used model fitting Coats-Redfern method using TGA data. A kinetics study of thermal decomposition has been done for both untreated and treated fiber with the help of TGA using a single heating rate of 10 °C/min. This analysis shows that treated sunnhemp fibers have variable activation energy based on the different models chosen. The estimated activation energy is in the range of 30.0–76.6 kJ mol−1 for the untreated sample & for the treated sample it is in the range of 34.58–67.12 kJ mol−1. Here the two phases have been selected as per temperature ranges in which inherent component decomposes during pyrolysis. In each phase, kinetics and thermodynamic parameters (ΔS, ΔH & ΔG) are also estimated. FTIR study of both samples confirms the concentration change of elements present in fiber due to the chemical treatment performed.

Kinetic modelling of mixed plastic waste pyrolysis

The study of plastic waste thermal decomposition and kinetics is a crucial step for optimal reactor design and the scale-up of pyrolysis technologies for chemical recycling. Kinetic parameters of individual and mixed plastic waste samples that resemble the main components of plastic waste streams (polyolefins and polyesters) were determined in this study using thermogravimetric analysis. Strong dependencies of activation energy on conversion were found for the mixtures, indicating that the process occurs in multiple steps and there are strong interactions between plastic components, lowering their activation energy during the decomposition. PP and LDPE decomposed via two separate steps whereas others decomposed via a single step process. For plastic mixtures, three dominant partially overlapping steps were identified. Kinetic deconvolution analysis improved model accuracy of mixtures and enabled the study of kinetic contributions and behaviour of individual steps. The models were then applied to predict experimental data at various heating conditions and plastic compositions.