Activation Energy Of Decomposition Research Articles

Insight into the thermal decomposition properties of potassium perchlorate (KClO4)-based molecular perovskite

Studying thermal decomposition properties of the perchlorate-based molecular perovskite energetic materials is essential to facilitate the potential applications. In this work, thermal decomposition properties of potassium perchlorate (KClO4)-based molecular perovskite were investigated. Potassium perchlorate -based molecular perovskite (H2dabco)[K(ClO4)3] were prepared by the one-pot reaction of KClO4, HClO4 and triethylenediamine (dabco). The samples were characterized. The results show that (H2dabco)[K(ClO4)3] has ternary organic-inorganic perovskite crystal structures. The thermal decomposition results demonstrated that molecular perovskite (H2dabco)[K(ClO4)3] has a lower decomposition temperature (383.6 °C) and a higher heat release (2815 J g−1) than 607.7 °C and 313 J g−1 of the monocomponent KClO4, respectively. The activation energy of thermal decomposition of (H2dabco)[K(ClO4)3] had been reduced appreciably from 191.2 kJ mol−1 to 177.7 kJ mol−1. A synergistic catalysis thermal decomposition mechanism based on unique molecular perovskite structure was proposed. This work offers a novel understanding for thermal decomposition of the molecular perovskite energetic materials.

Thermal decomposition and combustion performance of high-energy ammonium perchlorate-based molecular perovskite

The development of high-energy ammonium perchlorate (NH4ClO4, AP)-based energetic materials is of great significance for promoting their potential applications. In this study, AP-based molecular perovskite energetic materials (H2dabco)[NH4(ClO4)3] were prepared via molecular assembly strategy with the facile one-pot reaction of AP, HClO4 and triethylenediamine (dabco). The as-obtained sample was characterized by X-ray diffraction (XRD) and Fourier transform infrared (FT-IR). The thermal decomposition and combustion performance was investigated by thermo-gravimetric/differential scanning calorimeter (TG-DSC), high speed photography and three-dimensional FT-IR. The results showed that combined with the oxidizer perchlorate and fuel dabco at the molecular level, ternary molecular perovskite (H2dabco)[NH4(ClO4)3] possessed a more stable thermal decomposition temperature (385.0 °C) than the monocomponent AP and the heat release is also as high as 3421 J g−1. The thermal decomposition activation energy (181.070 kJ mol−1) of thermal decomposition of (H2dabco)[NH4(ClO4)3] had been expectably reduced from the activation energy (200.259 kJ mol−1) of high-temperature decomposition stage of AP, despite of low-temperature decomposition stage. The synergistic catalysis thermal decomposition mechanism based on the molecular perovskite structures was proposed. And the combustion performance demonstrated molecular perovskite (H2dabco)[NH4(ClO4)3] had a high energy-releasing efficiency. This work provides a proof-of-principle concept for the design and fabrication of high-performance solid propellants based on molecular perovskite (H2dabco)[NH4(ClO4)3].

Thermogravimetric Kinetics of Catalytic and Non-Catalytic Pyrolytic Conversion of Palm Kernel Shell with Acid-Treated Coal Bottom Ash

The catalytic and non-catalytic pyrolytic conversion kinetics of palm kernel shell (PKS) with untreated (as received) and H2SO4-treated coal bottom ash as catalyst were investigated in this study. Flynn-Wall-Ozawa (FWO) and distributed activation energy model (DAEM) isoconversional kinetic models were exploited to evaluate the kinetic parameters. The study was conducted using thermogravimetric analysis at 10, 20, 30, and 50 °C/min heating rates. The activation energy (Ea) and pre-exponential factor (A) for non-catalytic PKS decomposition for DAEM ranged from 74.39 to 217.05 kJ/mol and 4.77E+01 to 1.99E+14 s−1 at different conversions while for the untreated ash, the ranges were 103.84–402.53 kJ/mol and 7.35E+03–1.04E+29 s−1. In the decomposition with treated ash, Ea and A were 81.79–191.07 kJ/mol and 1.61E+02–1.20E+12 s−1 for 7 wt% ash and 74.41–137.35 kJ/mol and 4.91E+03–4.53E+08 s−1. Values of Ea and A obtained for FWO followed the same pattern and are in close agreement with that obtained using DAEM. The use of 10 wt% acid-treated ash reduced the activation energy compared with the non-catalytic process by about 33.05% while the untreated ash increased the activation energy. The kinetic parameters were determined satisfactorily using the first-order reaction mechanism.

Exploration of the thermal decomposition of zinc oxalate by experimental and computational methods

Zinc oxalate dihydrate has been synthesized by precipitation method and characterized by FT-IR, XRD and SEM-EDAX. The kinetics of dehydration and decomposition were studied by non-isothermal DSC technique in the N2 atmosphere at different heating rates: 4, 6, 8 and 10 K min−1. The product of thermal decomposition, ZnO has been characterized by UV, TEM, SEM-EDAX and XRD and found that the particles are in nanometer range. The activation energy for thermal dehydration and decomposition was calculated by various isoconversional methods. Furthermore, structure and reactivity of zinc oxalate have also been investigated using B3LYP/631+g (d, p) level of theory with the help of Gaussian 09W software. The theoretical investigation indicates that most probably the compound decomposes to ZnO along with the evolution of CO2 and CO.

Phosphorus Schiff base ligand and its complexes: Experimental and theoretical investigations

A phosphorus‐containing Schiff base was prepared from bis{3‐[2‐(4‐amino‐1,5‐dimethyl‐2‐phenylpyrazol‐3‐ylideneamino)ethyl]indol‐1‐ylmethyl}phosphinic acid and paraformaldehyde as a novel antibacterial compound. The reaction of the Schiff base ligand with VO(IV), Ni(II), Co(II), Cu(II), Zn(II), Cd(II), Hg(II), Pd(II) and Pt(IV) led to binuclear species of metal complexes, depending on the ratio of metal ion and ligand. The ligand and its complexes were investigated using elemental analysis, Fourier transform infrared, 1H NMR, 13C NMR, UV–visible and mass spectra, thermogravimetric analysis, conductivity measurements and thermal analysis. The results showed that the Schiff base behaves as a tetradentate ligand; moreover, on the basis of conductance results, of all the prepared complexes are non‐electrolytes, excepting the Pt(IV) complex. The metal complexes were found to be formed with a metal‐to‐ligand ratio of 2:1, except for the Pt(IV) complex with a ratio of 1:1. The activation thermodynamic parameters (ΔE*, ΔH*, ΔS*, ΔG* and K) and the activation energy of thermal decomposition were determined from thermogravimetric analysis using the Coats–Redfern method. The biological activities of the metal complexes were screened against the growth of bacteria and fungi in vitro to assess the antimicrobial potential and study the toxicity of the compounds. The prepared compounds have noteworthy antimicrobial properties.

Synergistic Effects of Furfural and Sulfuric Acid on the Decomposition of Levulinic Acid

The decomposition of levulinic acid (LA) is a critical factor limiting the yield of LA produced by biomass hydrolysis. In this study, the effects of influencing factors, especially furfural, on the decomposition of LA were investigated. Results show that furfural, as a hemicellulose hydrolysis product, led to an increase in LA decomposition; 25.3% of LA decomposed when furfural concentration was 0.3 mol/L at 200 °C. Furthermore, sulfuric acid, as a hydrolysis catalyst, was found to have a synergistic effect with furfural on LA decomposition, giving a maximum promotion of 9.86% on LA decomposition compared with the effect of acid or furfural alone. A kinetic model of LA decomposition considering the synergistic effect of furfural and acid concentration was established, and the activation energy of LA decomposition was found to be 34.46 kJ/mol.

Effect of tensile action on retrogradation of thermoplastic cassava starch/nanosilica composite

Thermoplastic cassava starch (TPS)/nanosilica (SiO2) composite was prepared by melt mixing, and the effect of tensile action (stress) on the structures and properties of TPS/SiO2 composite during the retrogradation stages was investigated. Differential scanning calorimetry (DSC) analysis indicated that the retrogradation enthalpy of TPS/SiO2 composite with the tensile action was higher than that of the composite without the tensile action after short retrogradation time. Thermogravimetric analysis (TG) displayed that the decomposition temperature and activation energy of thermal degradation of the composite under the tensile action were higher than those of composites without the tensile action. The contact angle and tensile strength of TPS/SiO2 composite with the tension action became larger after the tension stress was applied during the short retrogradation time. From the Fourier transform infrared (FTIR) spectroscopy results, the stretching vibration of the hydroxyl group enhanced with the increase in retrogradation time. According to the polarized light microscopy (PLM) analysis, the composite samples showed Maltese cross-pattern, and it became blurred after the tensile stress was exerted on the samples. With the increase in retrogradation time, the inter-planner spacing decreased and crystal size of TPS/SiO2 composite increased. The tensile action could weaken the A-type and promote the formation of the V-type crystalline structure. The scanning electron microscopy (SEM) results showed that the fracture surface of composite sample without the tensile action was smooth, and the granular structure of starch could not be clearly seen, however, the fracture surface of composite under the tensile action was rough, and the granular structure of starch was clear.

Highly efficient decomposition of toluene using a high-temperature plasma-catalysis reactor

Plasma-catalysis technologies (PCTs) have the potential to control the emissions of volatile organic compounds, although their low-energy efficiency is a bottleneck for their practical applications. A plasma-catalyst reactor filled with a CeO2/γ-Al2O3 catalyst was developed to decompose toluene with a high-energy efficiency enhanced by the elevating reaction temperature. When the reaction temperature was raised from 50 °C to 250 °C, toluene conversion dramatically increased from 45.3% to 95.5% and the energy efficiency increased from 53.5 g/kWh to 113.0 g/kWh. Conversely, the toluene conversion using a thermal catalysis technology (TCT) exhibited a maximum of 16.7%. The activation energy of toluene decomposition using PCTs is 14.0 kJ/mol, which is far lower than those of toluene decomposition using TCTs, which implies that toluene decomposition using PCT differs from that using TCT. The experimental results revealed that the Ce3+/Ce4+ ratio decreased and Oads/Olatt ratio increased after the 40-h evaluation experiment, suggesting that CeO2 promoted the formation of the reactive oxygen species that is beneficial for toluene decomposition.

Compatibility study of theophylline with excipients using thermogravimetry supported by kinetic analysis

Thermogravimetry was applied to a compatibility study between theophylline and excipients such as glicocol, glucose, sorbitol, sucrose, cellulose and arabic gum. The technique is extremely useful in studies involving non-isothermal kinetic with a Flynn and Wall model. Based on the thermogravimetric data obtained, the activation energy (Ea) of decomposition for theophylline, excipients and their binary mixtures was determined using four different heating rates. With an increase in heating rate, the decomposition of samples under study was shifted to higher temperatures in conjunction with an increase in the rate of mass loss. The activation energy of theophylline decreased with an increase in conversion degree. It is valid to assume that the values of Ea of theophylline mixtures with glicocol and cellulose are similar to the Ea values of theophylline alone. Hence, it may be assumed that glicocol and cellulose are compatible with theophylline, findings confirmed by DSC, FTIR and PXRD. The results obtained show that kinetic parameters calculated using a thermogravimetric curve can be employed to improve TG interpretation and to predict more accurately the compatibility/incompatibility of theophylline with excipients.

Synthesis, characterization and thermokinetic analysis of the novel sugar based styrene co-polymer

Abstract A new α-chloralose (1,2-O-(R)-trichloroethylidene-α-D-glucofuranose)-based copolymer of styrene (PSVTEG) (2) was synthesized from vinyl (hydroxyl) furan monomer (1) and styrene by a conventional free radical polymerization reaction. The thermal decomposition kinetics of polymer were investigated by means of thermogravimetric analysis in dynamic nitrogen atmosphere at different heating rates. The apparent activation energy for the main stage thermal decomposition of the copolymer PSVTEG (2) was calculated using the Flynn-Wall-Ozawa and found to be 159.0±3 kj/mol. In addition, the activation energy value was calculated according to Coats-Redfern method and found to be compatible with the obtained result. The thermogram of the glycopolymer (PSVTEG) (2) has two decomposition stages and the calculated activation energy indicated that the main degradation stage is a nonspontaneous process (integral form 1/(1−α)2 for F3).

Effect of weight percentage of B4C reinforcement on physical and mechanical properties of polyamide 6/polystyrene composites

ABSTRACT Blends of polyamide 6/polystyrene (PA6/PS) (50/50 wt./wt. %) were loaded with different concentrations of boron carbide (B4C), (0, 5, 10, 15, 20 and 30 wt./wt. %) separately for EMI shielding. The effects of different weight fractions of fillers on thermal, electrical, as well as, mechanical behavior of the prepared composites were investigated. Thermal stability and hardness (shore D) of composites are studied. Addition of B4C enhances thermal stability of the prepared composites which attributed to the increase in physical and chemical cross-linking points, also to the interactions between the filler and polymer blend. Confirmation of thermal stability was done by determining the activation energy (E a) for the thermal decomposition of all composites. Characterization of the prepared composites was done using SEM. With B4C-loaded PA6/PS blend composites, samples of 2 mm thick, SE values of 5–36 dB were achieved, satisfying the requirement for common commercial applications.

Tert-Butanol intervention enables chemoselective conversion of xylose to furfuryl alcohol over heteropolyacids

tert-Butanol protection enables the chemoselective production of furfuryl alcohol directly from xylose over heteropolyacids using formic acid as a hydrogen honor.

Пиролиз обработанной огнезащитными составами древесины погонажных изделий

New opportunities are opening up today to study the nature and mechanisms of processes occurring in wood when exposed to temperatures. The study of the thermal behavior of untreated and treated with fire retardant compounds of wood of different species using synchronous thermal analysis in an inert and oxidizing atmosphere. The apparent activation energies of decomposition of the samples and the rate of heat release are calculated. An idea of the effect of the studied flame retardant compounds is obtained. Coke residues after pyrolysis were examined using a scanning electron microscope. It was found that the surface structure of the coke residue accurately repeats the pattern of biological macrostructures of wood and is unique for each species, and the elements that make up the impregnation remain on the wood surface.

Characterization of kerogen content and activation energy of decomposition using machine learning technologies in combination with numerical simulations of formation heating

Reliable estimation of organic matter characteristics is essential in source and reservoir rocks evaluation. Their measurement is generally based on well logging and experiments after core sampling. In this study, we present a different approach from these methods to evaluate the characteristics of organic matter, which is based on the numerical simulations in combination with machine learning technologies.Formation heating processes of organic-rich shales and in-situ pyrolysis of kerogen are numerically simulated, where the time-series data of heater temperature are monitored. Here, we consider the whole organic matter composed with kerogen. The monitored heater temperature data are used as an input of inverse modeling by Artificial Neural Network (ANN) and Support Vector Machines (SVM) to figure out the characteristics of kerogen. Heater temperature acts as an indicator of type and maturity of kerogen, since it is affected by the bulk thermal conductivity of formation, which is a function of dynamically changing rock-and-pore composition by kerogen decomposition.We simulate the processes of electrical heating of 300 different formations, containing either one of Type 1, 2, or 3 kerogen with various amounts and activation energies. ANN method is employed to generate a data-driven model to estimate the unknown kerogen content and activation energy using heater temperature as an input data. SVM method, which categorizes dataset into the multiple classes by using hyperplanes, is applied to classify the dataset of heater temperature into different types of kerogens. Developed ANN and SVM models show great performances in the inversion and classification.The suggested characterization method provides a simple tool of estimating reactivity and type of kerogens. It will be used as a proxy for the inverse modeling of geochemical characterization of organic matter coupled with forward numerical simulations, by reducing the number of simulation runs required in the traditional inverse modeling.

Nanochromates MCr2O4 (M = Co, Ni, Cu, Zn): Preparation, Characterization, and Catalytic Activity on the Thermal Decomposition of Fine AP and CL-20.

The chromate nanoparticles such as CoCr2O4, NiCr2O4, CuCr2O4, and ZnCr2O4 were prepared by a modified sol–gel method. The structural and morphological properties of the chromate nanoparticles were characterized by X-ray diffraction (XRD) and a scanning electron microscope (SEM). The catalytic effects of chromates on the thermal decomposition of fine ammonium perchlorate (FAP) and hexanitrohexaazaisowurtzitane (CL-20) were studied by the TG-DTG measurements. Results show that the addition of CoCr2O4, NiCr2O4, CuCr2O4, and ZnCr2O4 nanoparticles makes the activation energies for the thermal decomposition of FAP decrease by 93.9, 94.0, 83.1, and 67.0 kJ·mol–1, and the thermal decomposition temperatures decrease by 45.0, 24.9, 57.7, and 38.8 K respectively. On the other hand, a similar trend exists in the case of the thermal decomposition of CL-20. Therefore, the addition of nanochromates shows high catalytic efficiency on the thermal decomposition of both FAP and CL-20 components, which would be beneficial to promote the burning rate of propellants containing FAP and CL-20 components.

Study on Blending of Wall Material of the Nonel Tube by CSW/PE-g-MAH.

In order to improve the strength and resistance of ordinary nonel tubes, calcium sulfate whiskers (CSW, treated with silane coupling agent) and maleic anhydride grafted polyethylene (PE-g-MAH) are used to control the wall material of the nonel tube that the blending of the low-density polyethylene was enhanced. The effects of mass fraction of CSW or PE-g-MAH on the tensile properties, interfacial structure, melting and crystallization characteristics, and thermal decomposition behavior of the composite system were studied, and the thermal decomposition kinetics were calculated. The results show that, relative to pure LDPE, the strength of LDPE/CSW (85/15) is increased by 7.58%, and the strength of LDPE/CSW/PE-g-MAH (84/15/1) is increased by 7.58%. The addition of CSW or PE-g-MAH has gradually changed the fracture mode of the LDPE matrix. Thermal analysis shows that CSW can reduce the crystallinity of LDPE. The melting and crystallization characteristics of LDPE/CSW/PE-g-MAH composites have little effect, but the thermal decomposition stability is improved. The kinetic analysis showed that the reaction order (n) was around 1, CSW could improve LDPE/CSW thermal decomposition activation energy, and PE-g-MAH increased the thermal decomposition activation energy of LDPE/CSW/PE-g-MAH.

Effects of Nanosized Metals and Metal Oxides on the Thermal Behaviors of Insensitive High Energetic Compound ICM-102

In this paper, the composites of a newly insensitive high explosive 2,4,6-triamino-5-nitropyrimidine-1,3-dioxide (ICM-102) with nanosized metals (Al, Co, Mg, Si, Ti, and Zr) and nanosized metal oxides (CuO and Fe2O3) have been prepared and investigated in terms of thermal reactivity. The catalytic effects on the thermal decomposition of ICM-102 composites have been investigated by TGA-DSC technique. Among all the composites, ICM-102/Co shows the minimum residue rate of 1.57 wt % and ICM-102/Si shows the maximum heat release of 1001.9 J g–1. The kinetic parameters for the catalytic decomposition of ICM-102 have been obtained. The activation energy (Ea) of ICM-102 decomposition is within 197.9–212.0 kJ mol–1. Compared with ICM-102, the Ea of ICM-102/Si decomposition was decreased by about 90 kJ mol–1. The decomposition gaseous products of ICM-102 and its composites have been analyzed by the TG-MS technique. It has been shown that the main gaseous products are H2O, C2H4, C3, and C2N or C3H2. The ICM-102 deco...

Physicochemical characterizations, antimicrobial activity and non-isothermal decomposition kinetics of Cinnamomum cassia essential oils

ABSTRACTThe extraction of essential oils from Cinnamomum cassia bark and leaf was carried out by hydrodistillation (HD) and microwave-assisted hydrodistillation (MAHD). Chemical compositions of volatile compounds were determined by GC/MS, 1H-NMR and infrared spectroscopy analysis. The dominant constituents found in the essential oils were aromatic compounds (> 90%) including (E)-cinnamaldehyde (CAL) and (E)-cinnamyl acetate (CAC) as the major components. The thermogravimetry (TG) method was used to study thermal stability and volatilization of the oils at room temperature. The bark essential oils exhibited inhibitory effects against a bacterial strain, S. aureus and a yeast strain, S. cerevisiae at MIC value 200 µg/mL. The decomposition kinetic of the essential oils was studied via the isoconversional kinetic models using the TG data. Two the isoconversional models, Flynn–Wall–Ozawa (FWO) and Kissinger–Akahira–Sunose (KAS) were used to determine activation energies (Ea) for decomposition of the essential oils.

Synthesis, thermal stability and kinetic decomposition of triblock copolymer polypropylene glycol–poly glycidyl nitrate–polypropylene glycol (PPG–PGN–PPG)

An energetic triblock copolymer PPG–PGN–PPG (Mn = 1886 g mol−1) was synthesized for the first time by cationic ring-opening polymerization of propylene oxide with low molecular weight poly glycidyl nitrate (PGN) (Mn = 1061 g mol−1) as a macroinitiator, in the presence of boron trifluoride etherate (BF3·OEt2) as the catalyst. The product obtained in high yield was characterized by FTIR, gel permeation chromatography and 1H and 13C NMR spectroscopy. The thermal properties of the triblock copolymer were characterized by differential scanning calorimeter (DSC). The result approved that the glass transition temperature of the triblock copolymer (Tg = − 58 °C) is lower than PGN (Tg = − 35 °C); also, it was more stable than that of PGN. The effect of heating rates (10, 20, 30 and 40 °C min−1) on the decomposition of the copolymer was evaluated. The decomposition temperature of this compound increased as the heating rate increased. The kinetic parameters such as activation energy and frequency factor for the thermal decomposition of the triblock copolymer were obtained from the DSC and DTG data by non-isothermal methods proposed by the ASTM E696, Flynn–Wall–Ozawa (FWO) and Kissinger methods. The values by the FWO method are in good agreement with ASTM and Kissinger methods.

An assessment of how distance and diesel oxidation catalyst will impact thermal decomposition behaviors of particles

Decomposition mass loss and pyrolysis products analyses of particles sampled at various locations along the tailpipe of a Euro-IV diesel engine were performed using a thermogravimetry in conjunction with Fourier transformation infrared spectrometry-mass spectrum. Diesel particles were collected at the same location with and without diesel oxidation catalyst (DOC) mounted on the test engine separately. The three poles in thermal gravity-differential thermal gravity images suggested that the decomposition process of diesel particles could be divided into three stages which correspond to the decompositions of lower boiling substances, higher boiling substances and soot respectively. It is noticed that no matter whether DOC was mounted or not, the further the particles were sampled away from the engine block, the lower the peak temperatures and the heavier the mass losses within the first two stages, which indicated that the soluble organic fraction in the particle samples increased and therefore lowering the activation energy of thermal decomposition. Hydroxyl, ammonia, CxHy fragments, benzene, toluene, and phenol were found to be the primary products of particle decomposition, which didn't change with the location of particle sample point. The employment of DOC increased the activation energy for particle oxidation and resulted in a higher peak temperature and lower mass loss within the first-stage. Moreover, the CO stretching bands of aldehyde and ketone at 1771 cm−1 was only detected without a DOC, while the NO2 peak at 1634 cm−1 was solely noticed with the presence of DOC. Compared to the first-stage pyrolysis products, more polycyclic aromatic hydrocarbons and less CxHy fragments were seen in the second-stage.