Thermal Decomposition Process Research Articles

Pengaruh Suhu dan Waktu Pirolisis terhadap Karakteristik Arang dari Tempurung Kelapa

The increased production of coconut has increased by the shell produced, even though this coconut shell has lignin content of 33.30% so it has the potential to be converted into charcoal through the pyrolysis process. Pyrolysis is a thermal decomposition process that occurs without air or with little air to convert biomass into charcoal. Coconut shell charcoal can be used for coal co-firing in developing new and renewable energy. This study aimed to obtain the best pyrolysis temperature and time in the manufacture of high-calorific value coconut shell charcoal in accordance with SNI 06-4369-1996. Coconut shell pyrolysis was carried out at temperatures of 350 °C, 450 °C and 550 °C and pyrolysis times of 2 hours, 3 hours and 4 hours. The results showed that charcoal with the highest calorific value was produced at a temperature of 450 °C and a pyrolysis time of 3 hours. The resulting charcoal had calorific value of 7,750.96 cal/g, yield of 30.10%, and contained 2.75% water, 2.70% ash and 9.50% volatile matter.

Kinetics of the oxidative aging of phthalonitrile resins and their effects on the mechanical properties of thermosets

The process of thermal oxidation decomposition of phthalonitrile resins which had been post-cured at various temperatures (603 K, 623 K and 648 K) was studied using dynamic and isothermal measurement modes. It was shown that the degradation process is a complex branched four-stage process. We have concluded that the first stage is an nth order reaction with autocatalysis. The second stage is described with the expanded Prout-Tompkins equation which corresponds to an autocatalytic solid-state reaction caused by the formation of imperfections at the reaction surface. The third and fourth stages are also reactions of the nth order. The phthalonitrile resin post-cured at 603 K exhibited better thermal stability than the resins post-cured at 623 K and 648 K based on the activation energies of the 1st stage – 132 kJ/mol, 104 kJ/mol, and 106 kJ/mol respectively. These data were confirmed by comparable experimental activation energy values (111 kJ/mol, 87 kJ/mol, 86 kJ/mol respectively) and changes in mass loss and flexural strength values determined during long-term thermal aging in the temperature range of 553–623 K. It was shown that the phthalonitrile resin post-cured at 603 K with the initial flexural strength of 107 MPa is suitable for long-term application at temperatures up to 573 K.

In Situ Detecting Thermal Stability of Solid Electrolyte Interphase (SEI).

Solid electrolyte interphase (SEI) plays an important role in regulating the interfacial ion transfer and safety of Lithium-ion batteries (LIBs). It is unstable and readily decomposed releasing much heat and gases and thus triggering thermal runaway. Herein, in situ heating X-ray photoelectron spectroscopy is applied to uncover the inherent thermal decomposition process of the SEI. The evolution of the composition, nanostructure, and the released gases are further probed by cryogenic transmission electron microscopy, and gas chromatography. The results show that the organic components of SEI are readily decomposed even at room temperature, releasing some flammable gases (e.g., H2 , CO, C2 H4 , etc.). The residual SEI after heat treatment is rich in inorganic components (e.g., Li2 O, LiF, and Li2 CO3 ), provides a nanostructure model for a beneficial SEI with enhanced stability. This work deepens the understanding of SEI intrinsic thermal stability, reveals its underlying relationship with the thermal runaway of LIBs, and enlightens to enhance the safety of LIBs by achieving inorganics-rich SEI.

Pyrolysis and Oxidative Thermal Decomposition Investigations of Tennis Ball Rubber Wastes through Kinetic and Thermodynamic Evaluations

Thermal decomposition of tennis ball rubber (TBR) wastes in nitrogen and air has been studied through thermogravimetric analysis. The samples were thermally decomposed from room temperature to 950 K at heating rates of 3 to 20 K/min with a purging flow of 30 cm3/min. The degradation features and specific temperatures for two purging gases are thus compared according to the nonisothermal results. Kinetic analyses of two thermal decomposition processes have been isoconversionally performed using differential or integral methods. The activation energy as a function of mass conversion has been thus obtained over the entire decomposition range, varying from 116.7 to 723.3 kJ/mol for pyrolysis and 98.2 to 383.6 kJ/mol for oxidative thermal decomposition. The iterative Flynn-Wall-Ozawa method combined with the linear compensation effect relationship has been proposed for determining the pre-exponential factor and reaction mechanism function, resulting in chemical order reaction models of f(α) = (1 - α)5.7 and f(α) = (1 - α)5.8 for describing pyrolysis and the oxidative thermal degradation of TBR wastes, respectively. With these kinetic parameters, very satisfactory matching against experimental data has been obtained for both gases. Additionally, the thermodynamic parameters, such as the changes of entropy, enthalpy and Gibbs free energy, over the whole thermal degradation processes have also been evaluated.

Synergistic flame retardant effect of a new N-P flame retardant on poplar wood density board

A new and efficient flame retardant consisting of Ammonium tris (2-hydroxyethyl) isocyanurate triphosphate (ATITP) was prepared by a solvent-free synthesis method for improving the flame retardancy of poplar wood density boards. The flame retardant mechanism was probed, and the mechanism of capturing combustion radicals, synergistically promoting charring and inhibiting heat was summarized. The density board treated with 20% ATITP had an ultimate oxygen index (LOI) of was up to 65.1%. In the experiment of cone calorimetry (CONE), the total heat release (THR) of flame retardant density board was reduced by 73.9% compared with the pure density board sample, while the heat release rate (HRR), CO and CO2 production were significantly reduced. In addition, the analysis with a thermogravimetric infrared coupler (TG-FTIR) and thermal cracking gas mass spectrometer (Py-GC–MS) revealed that the flame retardant exerted a gas-phase and condensed-phase flame retardant during the thermal decomposition process to alter the thermal cracking pathway of wood powder. It was demonstrated that the poplar density board treated with ATITP has good flame retardancy, which provides a simple and efficient method for flame retardant density board for building materials.

Synthesis of mesoporous silica and chitosan-coated magnetite nanoparticles for heavy metal adsorption from wastewater

The use of magnetic nano-sized adsorbents for the removal of heavy metals from water possesses significant potential in water remediation sector. The goal of this study was to develop economically feasible magnetite nanoparticles with an appropriate surface functionalization that will simultaneously provide adsorption efficiency, hydrophilicity, and recyclability without compromising magnetic properties. Magnetite nanoparticles (MNPs) were produced via the thermal decomposition process of iron oleate precursor due to monodispersity provided by this method. The particles were coated with mesoporous silica layers by utilizing cetyltrimethylammonium bromide (CTAB) as the surfactant. The coated particles were subjected to chitosan coating by stirring in chitosan solution. The success of the coating process was confirmed by performing Fourier-transform infrared spectroscopy (FTIR) analysis between each step. The particles were used as an adsorbent in heavy metal salts solutions of known concentrations. The adsorption study was conducted with varying contact time and initial concentration and the data was analyzed for fitting to pseudo 1st order and pseudo 2nd order kinetic models, and the Langmuir and Freundlich isotherm models to determine the adsorption characteristics. The kinetic model and isotherm fitting indicted that the adsorption occurred by monolayer chemical adsorption. The developed adsorbent exhibited a satisfactory adsorption capacity of 150.33 mg/g and 126.26 mg/g for Pb2+ and Cd2+ respectively which is a good indication for further exploration and analysis.

Pyrolytic characteristics, kinetics, thermodynamics, volatile products and chemical reactions of micron polypropylene infiltrated with kerosene

The pyrolysis of polymers infiltrated with combustible liquids is one common behavior in the fire accidents resulted by the leakage and overflow of combustible liquids over polymers. The present study may provide a theoretical basis and guidance for the prediction of fire development, the selection or design of fire detection and the design of ventilation and fire extinguishing systems. In the present study, the thermal decomposition behaviors, kinetics, thermodynamics, volatiles and chemical reactions of micron polypropylene (typical polymer) infiltrated with kerosene (typical combustible liquid) are investigated. It is concluded that the thermal decomposition process of micron PP with kerosene can be divided into two stages, and all stages can be considered as one-step reaction. As the kerosene content increases, the average and peak reaction rates of the first stage increase, while they decrease for the second stage and the whole process. As the heating rate increases, the average and peak reaction rates of the whole process decrease. In addition, increasing the heating rate or kerosene content may result in better combustion performance compared with that of pure PP. The calculated average activation energy, pre-exponential factor and global reaction model of the second stage can well predict the thermal decomposition behaviors of this stage. Thermodynamic analysis shows that the thermal decomposition of micron PP with kerosene is an endothermic and non-spontaneous reaction. The main volatile products contain olefins, alkynes, alkanes, hydrogen, carbon dioxide, carbon monoxide and aromatic compounds. The possible chemical reactions generating the above-mentioned products are deduced.

From PET Bottles Waste to N-Doped Graphene as Sustainable Electrocatalyst Support for Direct Liquid Fuel Cells

Direct liquid fuel cells represent one of the most rapidly emerging energy conversion devices. The main challenge in developing fuel cell devices is finding low-cost and highly active catalysts. In this work, PET bottle waste was transformed into nitrogen-doped graphene (NG) as valuable catalyst support. NG was prepared by a one-pot thermal decomposition process of mineral water waste bottles with urea at 800 °C. Then, NG/Pt electrocatalysts with Pt loadings as low as 0.9 wt.% and 1.8 wt.% were prepared via a simple reduction method in aqueous solution at room temperature. The physical and electrochemical properties of the NG/Pt electrocatalysts are characterized and evaluated for application in direct borohydride peroxide fuel cells (DBPFCs). The results show that NG/Pt catalysts display catalytic activity for borohydride oxidation reaction, particularly the NG/Pt_1, with a number of exchanged electrons of 2.7. Using NG/Pt composite in fuel cells is anticipated to lower prices and boost the usage of electrochemical energy devices. A DBPFC fuel cell using NG/Pt_1 catalyst (1.8 wt.% Pt) in the anode achieved a power density of 75 mW cm−2 at 45 °C. The exceptional performance and economic viability become even more evident when expressed as mass-specific power density, reaching a value as high as 15.8 W mgPt−1.

Comprehensive study on the thermal decomposition process of waste tobacco leaves and stems to investigate their bioenergy potential: Kinetic, thermodynamic, and biochar analysis

This work focuses on understanding the thermal decomposition process of tobacco wastes collected from cigarette factories, further evaluating the potential as bioenergy feedstocks. Thermogravimetric analysis was performed on waste tobacco leaves and stems under air and inert atmosphere. The calculated average activation energy of tobacco leaves is 173.11–173.91 kJ mol−1 (air) and 151.32–151.52 kJ mol−1 (N2), while it is 183.28–185.63 kJ mol−1 (air) and 168.50–168.81 kJ mol−1 (N2) for stems. Combined with kinetic and thermodynamic results, waste tobacco can be considered as a potential bio-feedstock energy source. In addition, the microstructure and structural property of residual biochar after pyrolysis were investigated, which has high carbon content, large specific surface area with abundant porosity, indicating the application potential in catalysis, adsorption, energy storage fields. The work aims to pursue the full re-utilization of tobacco residues from cigarette factories, achieving the effect of recycling and turning waste into treasure.

Study on the Thermal Decomposition of D-4OH PFPE Lubricant by Reactive Molecular Dynamic Simulation for HAMR

Heat-assisted magnetic recording (HAMR) is one of the ways of ultrahigh density storage technology. The pulsed laser in the HAMR head heats the nano-region of the disk to Curie temperature. The laser heating causes the decomposition of the PFPE lubricant, which indirectly leads to the failure of head-disk interface (HDI). The reactive molecular dynamics (MDs) simulations are performed to research the thermal decomposition of single and multiple D-4OH lubricants. The effect of three different heating rates on the thermal decomposition process of a single D-4OH lubricant is investigated. The decomposition processes of single and multi-D-4OH molecular chains are the same: the functional end groups degrade first and then the main chain. These results are useful for the optimization of PFPE lubricants for HAMR disks.

Growth of FeOCl nanoparticles via thermal decomposition under reduced pressure and rotation

Iron oxychloride as a catalyst or electrode material has been attracted attention in recent years. In this paper, the growth and agglomeration of FeOCl nanoparticles, which were synthesized by thermal decomposition method, have been studies systematically. The crystallized FeOCl was formed and agglomerated at a low temperature (140 ℃) under reduced pressure and rotation. The FeOCl crystal grew preferentially along the (010) crystal plane during a sustained thermal decomposition process, thus FeOCl nanosheets with a strip-shaped morphology were formed. With increasing reaction temperature, the size of the synthetized nanoparticles decreased but the agglomeration phenomenon became more prominent. Benefiting from the small nanosheet structure, the FeOCl-220-1 h cathode shows a maximum discharge capacity of 182 mAh g−1. However, after 15 cycles, a dramatic capacity decay was observed due to the pulverization of the agglomerated particles.

A new strategy to prepare magnetoceramics by bulk pyrolysis of Fe-containing polyamide precursors

In this work, a new strategy was developed to prepare magnetoceramics through a bulk pyrolysis of novel Fe-containing polyamide preceramic precursors at low pyrolysis temperature. A series of novel polyamides with different chemical structures were synthesized by bulk Michael addition and polycondensation, and their structures were characterized. Polymer precursors (PPs) were prepared by direct melt blending polyamides and FeCl3, and polymer-derived ceramics (PDCs) were prepared via the pyrolysis of PPs. The polyamide structure with pendant pyridine groups in repeating units makes the Fe complexes uniformly dispersed in matrix. The relationship between magnetoceramic compositions and PP structures was investigated by TGA, XPS, XRD, FE-SEM, FE-TEM and VSM characterizations. Different chemical structures and Fe catalysis effect lead to different thermal decomposition processes of PPs. Increasing crystal-Fe content in PDCs contributes to higher magnetic properties. The morphology of crystal phases in PDCs relies on the structures of PPs and pyrolysis temperature. Different pyrolysis temperatures and chemical structures of PPs bring about different Fe crystal phases and carbon crystal state of nanosheets or nanofiber bundles.

Theoretically Revealing the Response of Intermolecular Vibration Energy Transfer and Decomposition Process of the DNTF System to Electric Fields Using Two-Dimensional Infrared Spectra.

The external electric field (E-field), which is an important stimulus, can change the decomposition mechanism and sensitivity of energetic materials. As a result, understanding the response of energetic materials to external E-fields is critical for their safe use. Motivated by recent experiments and theories, the two-dimensional infrared (2D IR) spectra of 3,4-bis (3-nitrofurazan-4-yl) furoxan (DNTF), which has a high energy, a low melting point, and comprehensive properties, were theoretically investigated. Cross-peaks were observed in 2D IR spectra under different E-fields, which demonstrated an intermolecular vibration energy transfer; the furazan ring vibration was found to play an important role in the analysis of vibration energy distribution and was extended over several DNTF molecules. Measurements of the non-covalent interactions, with the support of the 2D IR spectra, indicated that there were obvious non-covalent interactions among different DNTF molecules, which resulted from the conjugation of the furoxan ring and the furazan ring; the direction of the E-field also had a significant influence on the strength of the weak interactions. Furthermore, the calculation of the Laplacian bond order, which characterized the C-NO2 bonds as trigger bonds, predicted that the E-fields could change the thermal decomposition process of DNTF while the positive E-field facilitates the breakdown of the C-NO2 in DNTFⅣ molecules. Our work provides new insights into the relationship between the E-field and the intermolecular vibration energy transfer and decomposition mechanism of the DNTF system.

Hematite: A Good Catalyst for the Thermal Decomposition of Energetic Materials and the Application in Nano-Thermite

Metal oxides (MOs) are of great importance in catalysts, sensor, capacitor and water treatment. Nano-sized MOs have attracted much more attention because of the unique properties, such as surface effect, small size effect and quantum size effect, etc. Hematite, an especially important additive as combustion catalysts, can greatly speed up the thermal decomposition process of energetic materials (EMs) and enhance the combustion performance of propellants. This review concludes the catalytic effect of hematite with different morphology on some EMs such as ammonium perchlorate (AP), cyclotrimethylenetrinitramine (RDX), cyclotetramethylenete-tranitramine (HMX), etc. The method for enhancing the catalytic effect on EMs using hematite-based materials such as perovskite and spinel ferrite materials, making composites with different carbon materials and assembling super-thermite is concluded and their catalytic effects on EMs is also discussed. Therefore, the provided information is helpful for the design, preparation and application of catalysts for EMs.

Polylactic acid flame‐retardant composite preparation and investigation of flame‐retardant characteristics

AbstractPolylactic acid (PLA) is a new type of biodegradable material with good mechanical properties, and is widely used in many fields. However, as PLA is highly flammable, it is necessary to conduct flame‐retardant modification research on PLA. Phosphorus heterophilic flame retardants are low smoke, non‐toxic and have high flame‐retardant efficiency, and also have broad application prospects. In this study, a phosphazene flame retardant, 9,10‐dihydro‐9‐oxa‐10‐phosphazene‐10‐yl‐hydroxy‐phenol (abbreviated as DOPO‐PHBA), was synthesized. The PLA/ECE/DOPO‐PHBA flame‐retardant composites were prepared by adding DOPO‐PHBA and epoxy chain extender (ECE) into PLA. Thermal, mechanical, and flame‐retardant properties, as well as microscopic morphology of the PLA flame‐retardant composites were characterized and analyzed, and the flame‐retardant mechanism was discussed. Results show that when the flame‐retardant DOPO‐PHBA is added at 5 wt%, the PLA composites can reach the V‐0 level of combustion, and the corresponding LOI value is 30.0% at this time, and the LOI value increases from 22.5% to 33.6% with the increase of the flame‐retardant content. In addition, PLA composites still have good mechanical properties, and the cone heat, carbon residue and the thermal decomposition process shows that the flame‐retardant causes a two‐phase flame‐retardant mechanism on PLA with the gas and condensed phases acting in synergy. High flame retardancy is mainly attributed to free radical quenching, gas dilution, and the thermal barrier caused by the carbon layer. This work provides a simple and scalable method for the preparation of high‐performance flame‐retardant PLA materials.

Influence of Surface-Modified Montmorillonite Clays on the Properties of Elastomeric Thin Layer Nanocomposites

In recent years, polyurethane nanocomposites have attracted more attention due to the massive demand for materials with increasingly exceptional mechanical, optical, electrical, and thermal properties. As nanofillers have a high surface area, the interaction between the nanofiller and the polymer matrix is an essential issue for these materials. The main aim of this study is to validate the impact of the montmorillonite nanofiller (MMT) surface structure on the properties of polyurethane thin-film nanocomposites. Despite the interest in polyurethane-montmorillonite clay nanocomposites, only a few studies have explored the impact of montmorillonite surface modification on polyurethane's material properties. For this reason, four types of polyurethane nanocomposites with up to 3% content of MMT were manufactured using the prepolymer method. The impact of montmorillonites on nanocomposites properties was tested by thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), contact angle measurement, X-ray diffraction (XRD), and optical coherence tomography (OCT). The results showed that chemical and physical interactions between the polymer matrix and functional groups on the montmorillonite surface have a considerable impact on the final properties of the materials. It was noticed that the addition of MMT changed the thermal decomposition process, increased T2% by at least 14 °C, changed the hydrophilicity of the materials, and increased the glass transition temperature. These findings have underlined the importance of montmorillonite surface structure and interactions between nanocomposite phases for the final properties of nanocomposites.

Construction of 3DOM Fe2O3/CuO heterojunction nanomaterials for enhanced AP decomposition

The construction of ordered pore structure and heterostructure interface is considered as an effective strategy to optimize the activity and stability of nano catalysts. Herein, we have elaborately fabricated the p-n heterostructure nanocatalysts of three-dimensionally ordered macroporous (3DOM) Fe2O3-supported 2D copper oxide nanofilm using a simple impregnation method, abbreviated as 3DOM-Fe2O3/CuO. The prepared 3DOM Fe2O3/CuO shows interconnected and ordered macroporous channels, which provide considerable catalytic active sites and enrich the reactive oxygen concentration at the Fe2O3-CuO heterostructure interface. By adjusting the copper source concentration, 2D copper oxide nanofilm with varied thicknesses was introduced to readily regulate the morphology of the catalyst and the atom composition or electronic structure of the interface. When evaluated as a catalyst for ammonium perchlorate (AP) decomposition reaction, 3DOM-Fe2O3/CuO-3 testified the most satisfactory catalytic activity, reducing the high temperature decomposition peak of AP decreased by 105.27 °C and the decomposition activation energy (Ea) by 50 %. Based on the experimental results of this study and related theoretical researches, the following mechanisms are proposed: in the thermal decomposition process of AP, the generation of active oxygen is not only related to the active oxygen mechanism, but also may be related to the NO2-assisted mechanism.

Kinetic Study of Pyrolysis of Coniferous Bark Wood and Modified Fir Bark Wood

We report on the kinetics of pyrolysis of bark wood of four coniferous tree species: fir (Abies sibirica), larch (Larix sibirica), spruce (Picea obovata), and cedar (Pinus sibirica) denoted as FB, LB, SB, and CB, respectively. Thermogravimetry (TG) and differential scanning calorimetry (DSC) methods were used to study the influence of KCl and K3PO4 compounds on the process of thermal decomposition of fir bark and determine the main thermal effects accompanying this process. As a result of the studies carried out, it was found that KCl additives practically do not affect the decomposition of hemicelluloses, but they shift the maximum decomposition of the cellulose peak in the direction of decreasing temperature to 340.9 °C compared to untreated bark (357.5 °C). K3PO4 promotes the simultaneous decomposition of hemicelluloses and cellulose in the temperature range with a maximum of 277.8 °C. In both cases, the additions of KCl and K3PO4 reduce the maximum rate of weight loss, which leads to a higher yield of carbon residues: the yield of char from the original fir bark is 28.2%, in the presence of K3PO4 and KCl it is 52.6 and 65.0%, respectively. Using the thermogravimetric analysis in the inert atmosphere, the reaction mechanism has been established within the Criado model. It is shown that the LB, SB, and CB thermal decomposition can be described by a two-dimensional diffusion reaction (D2) in a wide range (up to 0.5) of conversion values followed by the reactions with orders of three (R3). The thermal decomposition of the FB occurs somewhat differently. The diffusion mechanism (D2) of the FB thermal decomposition continues until a conversion value of 0.6. As the temperature increases, the degradation of the FB sample tends to R3. It has been found by the thermogravimetric analysis that the higher cellulose content prevents the degradation of wood. The bark wood pyrolysis activation energy has been calculated within the Coats–Redfern and Arrhenius models. The activation energies obtained within these models agree well and can be used to understand the complexity of biomass decomposition.

Simulation of thermal decomposition of γ′-Fe4N using molecular dynamics method

α″-Fe16N2 is a promising environmentally friendly rare-earth-free permanent magnet material with ultra-high saturation magnetization. Recent research has demonstrated experimentally through a thermally quenching treatment using γ′ phase Fe4N as a precursor to synthesize α″-Fe16N2 in bulk format. In this research using Molecular Dynamics (MD) simulation, we investigated the γ′-Fe4N phase thermal decomposition process and the potential phase transition from face center cubic (fcc)-phase to body center tetragonal (bct)-phase. As nitrogen concentration is higher in γ′-Fe4N (5.9 wt. %) than that in α′-Fe8N or α″-Fe16N2 (3 wt. %), Nitrogen bond formation through atom diffusion is studied with a “Nitrogen-rich” grain boundary (GB) model to find out whether lower-Nitrogen content bct Fe–N solid solution can be formed. Modified Embedded Atom Method (MEAM) interatomic potential of Fe–N system is applied. Post-processing including Nitrogen bond mapping/tracking is also performed for the thermostat-controlled heating and quenching simulation process. We also applied virtual XRD computation to characterize the material crystallographic texture before and after the thermal treatment.

Thermal Decomposition Process Analysis of Jarosite Residue

In this work, a mineralogical study and thermal decomposition analysis of jarosite residue sample from a zinc plant were carried out. The mineralogical analysis showed that the jarosite residue is mainly composed of four components, including jarosites, sulfates–hydroxides, sulfides and spinel. The distribution of relevant metallic elements in these components was characterized using a sequential extraction process. The X-ray diffraction results showed that AFe3(OH)6(SO4)2 and ZnFe2O4 are the main components of the jarosite residue sample. The thermal decomposition mechanisms of ammoniojarosite and sodium jarosite were studied by TG-DSC (Thermogravimetric analysis–differential scanning calorimetry). The thermal decomposition process and the corresponding mechanism of the jarosite residue were analyzed. The jarosite thermal decomposition process includes the removal of crystal water, dihydroxylation and deammoniation, desulfonation of component jarosite and desulfonation of component zinc sulfate.