Thermogravimetric Analysis Experiments Research Articles

Experimental analysis of the effect of natural fibers and SiC filler on the thermal behavior of green biocomposites

AbstractThe present work deals with the thermal behavior investigation of new biocomposite materials intended to be used for process engineering applications. Particular attention is given to the thermal degradation of such materials. Thermal characterization at different scales is performed using thermogravimetric analysis (TGA) and cone calorimeter experiments. The main purpose is to compare the thermal behavior of new bamboo‐based and banana‐based Green Biocomposites (GBCs). An intumescent fire retardant (IFR) coating, which is a mixture of APP and boric acid was applied on the GBC sample surface to study the flame retardancy. The GBC samples was first manufactured using a vacuum resin transfer molding. TGA results showed that bamboo‐based (BM‐GBC) and banana‐based (Bn‐GBC) materials exhibits similar thermal degradation pattern. While cone calorimeter experiments revealed that BM‐GBC outperforms than Bn‐GBC. The IFR coating improved the flame retardancy of both GBCs by reducing the heat release rate as well as a noticeable reduction in terms of smoke emission. Finally, to improve the thermal stability of Bn‐GBC material, SiC powder is added as a filler. The IFR coating and SiC powder addition promotes considerably the thermal behavior of Bn‐GBC materials.

A molecularly imprinted polymer monolithic column with dual template and bifunctional monomers for selective extraction and simultaneous determination of eight phenolics from polycarbonate cups

A molecularly imprinted polymer (MIP) monolithic column was prepared in situ in a pipette tip using phenol and bisphenol A as dual templates, 4-vinyl pyridine and β-cyclodextrin as bifunctional monomers. It was used for the selective and simultaneous solid phase extraction of eight phenolics, including phenol, m-cresol, p-tert-butylphenol, bisphenol A, bisphenol B, bisphenol E, bisphenol Z, and bisphenol AP. The MIP monolithic column was characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis and nitrogen adsorption experiment. The results of selective adsorption experiments showed that the MIP monolithic column can selective recognize the phenolics and have excellent adsorption property. The imprinting factor for bisphenol A can be as high as 4.31, and the maximum adsorption capacity for bisphenol Z can reach 201.66 mg g−1. Under the optimal extraction conditions, a selective and simultaneous extraction and determination method for eight phenolics was established based on the MIP monolithic column and high-performance liquid chromatography with ultraviolet detection. The linear ranges (LRs) of the eight phenolics were 0.5–200 μg L−1, the limits of quantification (LOQs) and detection (LODs) were 0.5–2.0 μg L−1 and 0.15–0.67 μg L−1. The method was applied to detect the migration quantity of the eight phenolics from polycarbonate cups and had satisfactory recovery. The method has the advantages of simple synthesis, short extraction time, as well as good repeatability and reproducibility, which provides a sensitive and reliable strategy for extracting and detecting phenolics from food contact material.

Evolution hydrothermal aging resistance mechanism study of zirconium and manganese doped CeO2 catalysts in soot catalytic combustion based on low Miller indices crystal surface effect

The thermogravimetric analysis (TGA) experiments were carried out to reveal the mechanism of Zr and Mn doping on catalytic activity of CeO2 catalyst both fresh and after hydrothermal aging, and the lattice morphology and valence changes were characterized by means of Brunauer–Emmett–Teller (BET) method, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and H2-temperature programmed reduction (H2-TPR). Density functional theory (DFT) and molecular thermodynamics calculations were applied to investigate the change in catalytic activity, crystal surface energy and crystal morphology caused by hydrothermal aging. The maximum reaction rate temperature of fresh Mn/CeO2 (389 °C) is similar to that of CeO2 (371 °C) and lower than that of Zr/CeO2 (447 °C), but the catalytic performance of CeO2 decreases more severely after hydrothermal aging. The catalyst crystals show different degrees of crystal surface migration after hydrothermal aging, which leads to the reduction of Ce3+/Ce4+ ratio and the active sites shift. DFT calculations indicate that the doping of Zr and Mn reduces the surface energy of the low Miller indices surface and increases the oxygen vacancy formation energy, leading to better thermal stability and lower catalytic activity. The Zr and Mn doping also changes the adsorption energy and Gibbs free energy of H2O, which dominates the migration of (1 1 1) to (1 1 0) and (1 0 0) in the vapor environment. The crystal surface migration mechanism of CeO2 catalysts doped with Zr and Mn induced by H2O molecules at high temperature obtained in this study can provide a valuable addition to the regeneration of CeO2 catalysts in the after-treatment systems of diesel engines.

Effect of fire-retardant coating on bamboo and banana-based biocomposites: A comparative study thermogravimetric analysis and cone calorimeter tests

In this work, a thermal behaviour comparison of a new bamboo-based and banana-based Green Bio-Composites (GBC) is conducted using thermogravimetric analysis (TGA) and cone-calorimeter experiments. An Intumescent Fire-Retardant (IFR) coating (a mixture of Exolit IFR36 and boric acid) has been applied on the investigated GBC materials in order to explore the flammability resistance of such GBCs. Vacuum Bag Resin Transfer Moulding (VBRTM) technique has been used to manufacture the samples. TGA test have been conducted under oxidative atmosphere with three different heating rates while cone calorimeter tests have been performed with a horizontally exposure on the top surface of the sample. The outcomes of TGA revealed that Bamboo-based (BM-GBC) and Banana-based (Bn-GBC) materials exhibited similar thermal degradation patterns. However, BM-GBC outperformed Bn-based in the cone calorimetry analysis, this is proven by the fire reaction parameters as well as the higher char residue. In addition, IFR coating improved the flame retardancy of both GBCs, reduced the Peak Heat Release Rate (PHRR) by approximately 40–50% and smoke production (SEA) by 26%. SEM and EDS analysis of char residue were performed to deeply investigate the effectiveness of the IFR as a protecting layer.

Evolution hydrothermal aging mechanism for Ag/CeO2 catalysts in regeneration of catalytic diesel particulate filter with DFT calculation.

In order to avoid the high cost of existing precious metal catalyst like Pt, Ag/CeO2 was the most promising catalysts for mobile source soot emission control technologies, but there was a clear trade-off between hydrothermal aging resistance and catalytic oxidation performance hindered the application of this catalyst. In order to reveal the hydrothermal aging mechanism of Ag/CeO2 catalysts, the TGA (thermogravimetric analysis) experiments were investigated to reveal the mechanism of Ag modification on catalytic activity of CeO2 catalyst between fresh and hydrothermal aging and were also characterized with the related characterization experiments to in-depth research the lattice morphology and valence changes. The degradation mechanism of Ag/CeO2 catalysts in vapor with high-temperature was also explained and demonstrated based on density functional and molecular thermodynamics theories. The experimental and simulation data showed that the catalytic activity of soot combustion within Ag/CeO2 decreased more significantly after hydrothermal aging than CeO2 due to the less agglomerated, which caused by the decreased in OII/OI and Ce3+/Ce4+ compared with CeO2. As shown in density function theory (DFT) calculation, the decreased surface energy and the increased oxygen vacancy formation energy of the low Mille index surface after Ag modification led to the instability structure and the high catalytic activity. Ag modification also increased the adsorption energy and Gibbs free energy of H2O on the low Miller index surface compared to CeO2, indicating that the desorption temperature of H2O molecules in (1 1 0) and (1 0 0) was higher than (1 1 1) in CeO2 and Ag/CeO2, which led to the migration of (1 1 1) crystal surfaces to (1 1 0) and (1 0 0) in the vapor environment. These conclusions can provide a valuable addition to the regenerative application of Ce-based catalysts in diesel exhaust aftertreatment system the aerial pollution.

Combustion characteristics and kinetic analysis of co-combustion of desulfurized dust and pulverized coal

ABSTRACT With the rapid development of desulfurization process, how to efficiently utilize sintered desulfurized dust in the desulfurization process has always been a problem faced by a steel industry. In this paper, the physicochemical properties of Kubasi anthracite coal (RU), Shangwan bituminous coal (SW), and desulfurized dust (TL) were systematically studied by means of X-ray fluorescence spectrophotometer, scanning electron microscopy, and Raman spectroscopy. In addition, the combustion characteristics and mechanisms of anthracite, bituminous, and desulfurized dust mixtures were investigated by thermogravimetric analysis experiments. The results show that the particle size of TL is finer, the degree of graphitization of RU is higher, the combustibility of SW is better than that of RU, and the effects of TL addition on the combustion performance of RU and SW are different. The calculated results of combustion kinetics are in good agreement with the experimental results. With the addition of TL from 3 to 7 wt%, the activation energy of SW decreased from 44.00 to 37.30 kJ/mol. The results provide a theoretical basis for adding desulfurized dust to the blast furnace in the future.

Demonstrating an altered metal oxidation reaction mechanism correlated with variations in surface energy

Thermal processing of powder media such as annealing and quenching alters particle surface properties and can influence the powder's reactivity. In this study, thermogravimetric analysis (TGA) was performed with micro-sized (4 µm characteristic particle diameter) aluminum (Al) powder. Two powders were examined, namely, untreated Al (UN Al), i.e., procured from the manufacturer, compared with thermally processed Al by annealing and quenching (i.e., called super-quenched aluminum, SQ Al). TGA experiments were designed to compare the rate of oxidation of both materials. A new data processing technique was introduced that allows for a direct demonstration of altered reactivity by comparing the sample behavior during heating and cooling. The approach analyzes a normalized derivate drop of mass gain data throughout a programmed heating and cooling cycle depending on particle exposure time to oxygen at select temperatures. Results clearly confirm a difference between SQ Al and UN Al at temperatures around 600 °C, i.e., just below the Al melting temperature. The powders were also characterized using inverse gas chromatography (iGC) that showed a substantially higher surface energy of UN Al. Based on the experimental results, there is a correlation between Al reactivity and particle surface energy that substantiates recent observations of two different modes of Al particle combustion. Particle surface energy can be controlled to affect the mechanism for metal oxidation thereby affecting the rate of metal combustion.

CO2 gasification of dry quenching dust ash catalyzed in situ by soot

It's imperative to reduce the CO2 emissions in iron and steel manufacturing and improve the reaction rate of the CO2 gasification of dry quenching dust ash (DQDA). In this study, a new technology is proposed in which the CO2 gasification of DQDA is catalyzed by high-temperature soot (HS) in the high-temperature flue gas of a converter. In the experiments, a composite catalyst (FeO: Fe2O3 = 5:2) was used to stimulate the main Components of HS. The influence of the main components of HS (FeO, Fe2O3) on DQDA gasification with CO2 was evaluated by thermodynamic simulation calculation (FactSage 6.1), thermo-gravimetric analysis, and drop-tube furnace experiments at high temperatures. In addition, the catalytic efficiency was quantitatively evaluated by the α and β values, LHVs, and kinetic analyses using homogeneous and shrinking-core models. The results indicated that the HS has significant catalytic effects on the CO2 gasification of DQDA, and exhibited differing characteristics. The catalytic efficiency increased with temperature. At 1200 °C, the consumption of CO2 was increased from 24.13% without a catalyst to 30.76% with the HS composite catalysts. As a result, Fe, FeO, and Fe3C were the most common solid products catalyzed by HS. Experiments proved the new technology's practicality.

Reactive behaviors and mechanisms of cellulose in chemical looping combustions with iron-based oxygen carriers: An experimental combined with ReaxFF MD study

Biomass energy is one of the important and feasible renewable energy resources. Chemical looping combustion (CLC) can meet the requirements of efficient CO2 capture with low energy consumption. The combination of the two factors is intuitive and important for realizing carbon neutral energy processing and conversion. Cellulose is the component with the highest content in biomass. However, there is still a lack of clear understanding of the thermal conversion behavior and microscopic reaction mechanism of cellulose in CLC. In this work, the behaviors and mechanisms of cellulose in CLC with iron-based OCs were studied systematically based on the comprehensive technics of thermo-gravimetric analysis (TGA) experiments, kinetic models and molecular dynamic simulations. The reaction behaviors, kinetic mechanism, and complex reactive networks of cellulose under complex environmental interface conditions of CLC were revealed. Three different stages were revealed for thermal weight loss and reaction behavior of cellulose in CLC via TGA. The effects of different conversion rates and reaction stages on activation energy during CLC were described based on two model-free integration methods. The dynamic evolution of the CLC process was discussed by ReaxFF MD (reactive force field molecular dynamics) simulations. A complex reaction network of cellulose depolymerization and CO2 release in CLC was obtained.

Simple biphenyl derived porous aromatic frameworks with attractive xenon/krypton separation

Porous Aromatic Frameworks (PAFs) with ultramicropores have emerged as a significant contributor to the gas separation field. However, there is a lack of efficient and cost-effective methods for the practical application of PAFs. In this study, we successfully synthesized QS-PAFs economically using Friedel-Crafts arylation of biphenyl derivatives. The QS-PAFs were analyzed using nuclear magnetic resonance spectroscopy, Fourier transform infrared spectrum, thermogravimetric analysis, and N2 adsorption experiment. We found that the QS-PAFs have comparable pore size, considerable surface areas, and good stabilities. The results demonstrated their high gas uptake capacities for Xe and attractive selectivity for Xe/Kr separation.

Succinonitrile-Polymer Composite Electrolytes for Li-Ion Solid-State Batteries-The Influence of Polymer Additives on Thermomechanical and Electrochemical Properties.

A plastic crystalline electrolyte (PCE) consisting of 0.4 mol/L lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) in succinonitrile (SN) was blended with poly(ethylene oxide) (PEO), poly(vinylpyrrolidone) (PVP), poly(ethylene carbonate) (PEC), and polyacrylonitrile (PAN). The influences of the regarding polymers on thermomechanical properties of the PCE were studied systematically, utilizing differential scanning calorimetry, thermogravimetric analysis, and oscillation experiments. Depending on the chosen polymer, the melting temperature and overall crystallinity of the PCE were increased. For PCEs containing PEO and PVP, overall crystallinity was enhanced the most resulting in lamellae-like superstructures, identified by light microscopy images. Furthermore, the onset for the sublimation process of SN was shifted to higher temperatures, and the mechanical strength was increased by the presence of some polymers, with exception of PEC. Electrochemical characterization, including electrochemical impedance spectroscopy and linear sweep voltammetry, revealed ionic conductivities of 10-4 S/cm at room temperature for PCE with PAN and extended electrochemical stability windows of ≥4.5 V vs lithiated graphite for PCE with PEO. By correlating the thermomechanical and electrochemical properties, some structure-property relationships were drawn, pointing out great potential for specific tailoring of PCEs by polymer additives. The synergistic effect of increasing both, mechanical stability and ionic conductivity, made the PCE + PAN composition especially attractive for a possible application in batteries.

Variation of the mass susceptibility of sandstone after high-temperature heating

Burnt rocks usually exhibit magnetic enhancement, which can be used to detect the spontaneous combustion zone of a coal fire or locate the resources in burnt rocks. To elucidate the mechanisms underlying magnetic enhancement, sandstone is heated to high temperatures between 100 and 1200°C. The mass susceptibility of the sandstone is measured after cooling, and the magnetic characteristics are explained based on the changes in colour and porosity, thermogravimetric and differential thermal analysis experiments and the observation of thin sections of rocks and scanning electron microscopy images. The findings are as follows: (1) the magnetic susceptibility of sandstone increases rapidly by two orders of magnitude as the temperature rises above 800°C. (2) The oxidation of iron ions and the formation of magnetite enhance the magnetic susceptibility of sandstone. The formation of magnetite at 800°C significantly enhances the magnetic susceptibility. (3) The highest temperature experienced by a burnt rock can be evaluated by analysing the different responses of the susceptibility of sandstone to temperature. Furthermore, it is possible to use the magnetic anomaly of the burnt rock to locate it and develop and utilise the beneficial resources in the burnt rock.

Intensive carbon combustion in sintering packed bed via steam spraying: An experimental study on carbon monoxide emission reduction.

Improving the combustion efficiency of solid fuels is important for reducing carbon monoxide emissions in the iron ore sintering process. In this paper, the surface steam spraying technology is introduced in the sintering process based on the auxiliary combustion effect of steam on coke, and its potential to reduce carbon monoxide emissions is demonstrated. Thermogravimetric analysis experiments of coke breeze in air and air-steam mixed atmosphere are carried out, and the results show that the introduction of steam can reduce the concentration of carbon monoxide in the exhaust gas from 183×10-6 to 78×10-6. At the same time, the mechanisms of carbon monoxide emission reduction by surface steam spraying technology are analyzed from the thermodynamic and kinetic perspectives. Then, a series of laboratory-scale sintering pot tests are carried out under no spraying operation, interval spraying operation, and continuous spraying operation. The results indicate that both interval and continuous spraying operations can reduce carbon monoxide emissions. The optimal mode of steam spraying under the present experimental conditions is continuously spraying for 13 min at a volume rate of 0.053 m3/min. Compared with no spraying, the average carbon monoxide concentration in the exhaust gas is reduced from 7565×10-6 to 6231×10-6, and total carbon monoxide emissions for per ton sinter are reduced from 13.46 m3/t to 9.51 m3/t.

Studies of caprolactam and cyclic oligomer content, molecular weight, and thermal properties during melt post-polycondensation of polycaprolactam in the film state

In industrial application of polycaprolactam, the content of caprolactam monomer and oligomers, as well as their average molecular weight are the key factors. In this work, a liquid-chromatography/time-of-flight mass spectrometry (LC-TOF-MS) method and an advanced polymer chromatography/multi-angle laser light scattering/refractive index detector (APC-MALLS-RID) hyphenated technique have been developed as a quantitative analysis method for monomer and cyclic oligomers, and a means of determining the molecular weight of polycaprolactam. The melt post-polycondensation reaction characteristics of polycaprolactam films and the variation in monomers and cyclic oligomers (C2–C7) content have been systematically investigated. The results showed excellent repeatability and stability of quantitative test results on monomers and cyclic oligomers in polycaprolactam. The content of monomers and cyclic oligomers in the polycaprolactam decreased from 10.21% to 1.52% at 260 °C and 50 Pa for 60 min, and the average molecular weight increased from 1.53×104 g/mol to 2.36×104 g/mol. Additionally, the results of differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) experiments showed that the thermal stability and crystallization properties of polycaprolactam were improved after the film melt post-polycondensation reaction. Thus, this melt post-polycondensation method can realize the efficient removal of monomers and cyclic oligomers (compared with the traditional hot water extraction method) and afford high-quality polycaprolactam with high average molecular weight.

Thermal decomposition of vegetative fuels and the impact of measured variations on simulations of wildfire spread

This manuscript presents new measurement data from milligram-scale thermal decomposition experiments – thermogravimetric analysis (TGA) and microscale combustion calorimetry (MCC) – conducted on stems and leaves (i.e., needles) of six plant species commonly found across the United States. For each fuel, measurement data from TGA experiments was analyzed to determine effective thermal decomposition mechanisms and the associated kinetics of their constituent reactions. Results of this model calibration were compared to standard (i.e., ‘generalized’) approaches to obtain kinetic parameters available in the literature. MCC experiments were repeated under identical experimental conditions to determine the heats of complete combustion of all gaseous volatiles produced by these vegetative fuels and to validate the decomposition mechanisms and species char yields determined from TGA data. Through a coupled analysis of TGA and MCC measurement data, an estimate of the heats of combustion of the gaseous volatiles produced by individual reaction steps in the fuel’s decomposition was also made. Between different fuels, distinct differences were measured in the onset temperature of decomposition, the temperature range of decomposition, the number of apparent reactions, and the peak measured mass loss and heat release rates (as well as the temperatures at which they occur). To analyze the impact of these variations on predictions of wildfire behavior, a modeling study was then conducted in which simulations of wildland fire experiments were repeated using the thermal decomposition mechanisms and heats of combustion determined for each of the fuel species tested in this work. Model-predicted fire spread rate in these simulations varied between 0.34 m s−1 and 0.80 m s−1 demonstrating a notable dependence (up to a factor of 2x) on measured variations in thermal decomposition mechanism and a second-order dependence on the use of either reaction-step-specific or single (global) heats of combustion.

Thermal desorption mechanism of n-dodecane on unsaturated clay: Experimental study and molecular dynamics simulation

Thermal desorption technology can effectively remediate fuels-contaminated clayey soil. However, the microscopic mechanism for the contaminant desorption on clay is still unclear, especially with the existence of water on clay surfaces. In this study, a combination method including TGA experiments, multi-phase and multi-component kinetic models, and MD simulation was proposed to reveal the thermal desorption mechanism of n-dodecane in unsaturated clay. Results showed that the thermal desorption behavior of the free nonaqueous phase liquid (NAPL) and the adsorbed phase of n-dodecane or water could be identified by the multi-phase and multi-component kinetic models based on the desorption process rate obtained by thermogravimetric analysis (TGA) experiments. The activation energy of the NAPL phase (49–69.9 kJ/mol) was lower than the adsorbed phase (90 kJ/mol). The activation energy of the NAPL phase had the same linear relationship with its mass on kaolinite and montmorillonite, while adsorbed phase only existed on the kaolinite surface. MD simulation showed that water demonstrated competitive adsorption with n-dodecane on montmorillonite surfaces and prevented the formation of the adsorbed phase while having little influence on the n-dodecane adsorption on kaolinite surface, which agrees well with the kinetic analysis of the TGA experiments. With the combination of macroscopic experimental analysis and microscopic molecular simulation, it can be concluded that the mass of the NAPL phase limited the desorption behavior, while the interaction between the clay mineral surface and n-dodecane was the key factor that dominated the thermal desorption behavior of the adsorbed phase. The presented results provide new insight into the desorption mechanism of hydrocarbon on clay minerals, which is of significance for the design of thermal desorption remediation.

Efficient reduction of NOx emissions from waste double-base propellant in co-pyrolysis with pine sawdust

Co-pyrolysis technology containing biomass offers remarkable advantages in reducing NOx emissions economically and efficiently. In this work, it was innovatively introduced to solve the problem of excessive NOx emission during the incineration of waste energetic materials (EMs). The kinetics and NOx emission characteristics of waste double-base propellant (DP), pine sawdust (PS), and their mixtures with different ratios during pyrolysis were investigated by thermogravimetric analysis and fixed-bed experiments. The results showed that there was a significant interaction between DP and PS. Kinetic analysis by Friedman and Kissinger-Akahira-Sunose (KAS) methods demonstrated that the average activation energies of the mixtures with different ratios were smaller than that of DP, indicating that the addition of PS improved the reactivity of co-pyrolysis. In addition, the fixed-bed experiment determined that the lowest NOx emission was achieved during DP pyrolysis alone at 900 ℃. Co-pyrolysis at this temperature was found to have synergistic effects of reduced NOx emissions for different ratios of mixtures. The best synergistic effect was achieved at the mixing ratio of 60 wt% DP and 40 wt% PS, resulting in a 72.11 % reduction in actual NOx emissions compared to the expected value. This study provides a new direction and powerful data support for the clean, efficient and economic treatment of waste EMs, especially for practical engineering strategies.

Activation energies and evolved gas analysis for Argonne premium coals

ABSTRACT A set of eight coals from the premium Argonne coal sample program were studied using thermogravimetric and evolved gas analysis. Gaseous combustion products were analyzed using an FTIR spectrometer and a chemiluminescence analyzer. Additionally, modulated thermogravimetric experiments were carried out to determine activation energies associated with the combustion of each sample. The exhaust from the thermogravimetric analyzer was directed to the gas analyzers for detecting and quantifying CO, CO2, and NO. Evolved gas analysis was conducted at a ramp rate of 5°C for CO, CO2 evolution, and 20°C per minute for nitric oxide evolution, with the furnace temperature varying between 20°C–750°C. Modulated thermogravimetric analysis experiments were carried out in the same temperature range. The temperature was increased at a rate of 2°C per minute for the modulated experiments. Each test had a superposed temperature modulation with amplitude ±5°C and a period of 200 seconds. The experiments provide valuable information on the combustion kinetics and emission characteristics of selected American coals.

Inverse modelling of pyrolization kinetics with ensemble learning methods

To simulate fire spread, especially the pyrolysis process – the thermal decomposition of a solid material – must be predicted. Yet, needed material dependent reaction kinetic parameters cannot be directly measured. Common methods infer them from small scale tests with inverse modelling approaches, which are computationally costly. Here, a novel machine learning based approach utilising extremely randomized trees (ERT) is presented and evaluated. It aims to derive these parameters almost instantly due to an inverse pre-trained surrogate model. The approach consists of an ERT classifier, a non-linear least squares optimiser and an ERT regressor. A thorough hyperparameter study was conducted. The model is evaluated with a synthetic thermogravimetric analysis (TGA) dataset. Calculated from an Arrhenius model, it contains data for more than 18⋅106 synthetic materials consisting of up to three components. The method is also applied on real experimental data, here polymethyl methacrylate (PMMA), gained from the Measurement and Computation of Fire Phenomena (MacFP) working group. Evaluation of the model demonstrated that it can instantly predict reaction kinetic parameters from TGA experiments for synthetic and real materials. Systematic analysis showed an overall R2 score of 0.77 for the complete model predictions. The code and datasets are published as open access.

Hydrothermal aging mechanism of K/CeO2 catalyst in soot catalytic combustion based on the Ostwald ripening mechanism

The thermogravimetric analysis (TGA) experiment of CeO2 and K/CeO2 catalysts prepared with the incipient wetness impregnation method was carried out for the soot catalytic combustion at different K loadings before and after hydrothermal aging. The structure, morphology, and catalytic activity of CeO2 and K/CeO2 catalysts were thoroughly investigated with the means of N2 adsorption/desorption, XRD, XPS, and H2-TPR. The density functional theory (DFT) operation was applied to explain the mechanism of the decrease in catalytic activity of CeO2 and K/CeO2 catalysts after hydrothermal aging. TGA showed that the Tmax of the hydrothermal aging K/CeO2 catalyst was 505 °C, which was higher than CeO2 at 473 °C. After hydrothermal aging, CeO2 catalysts were less agglomerated than K/CeO2, and the ratio of Ce3+/Ce4+ decreases, but the mobile oxygen OII/OI ratio in the lattice were increased compared to CeO2 catalysts. DFT calculations showed that K doping significantly increases the surface energy and decreases the oxygen vacancy formation energy of (1 1 1), (2 0 0), (2 2 0), and (3 1 1) crystal planes, leading to enhanced catalytic combustion performance of the K/CeO2 catalyst soot based on the Mars-Van Krevelen mechanism. Furthermore, K doping decreased the adsorption energy of H2O and the energy barrier of K atoms diffusing near the surface of K/CeO2 catalyst crystals from 5.92 eV to 2.46 eV, which resulted in the loss of the active center number because of migration and coalescence (sintering) caused by crystal plane instability based on the Ostwald ripening mechanism.