Thermogravimetry Mass Spectrometry Research Articles

Experimental study on the influence of water immersion on spontaneous combustion of anthracite with high concentrations of sulfur-bearing minerals

The influence of water immersion on the spontaneous combustion characteristics of anthracite with high concentrations of sulfur-bearing minerals was studied using simultaneous thermogravimetry–mass spectrometry (TG-MS), Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction. In addition, variations in the structural parameters, mass, heat release and gas evolution processes before and after water immersion were investigated. The results showed that the coal sample contained a large amount of pyrite (FeS2). After 45 days of immersion, the pyrite content in the coal decreased, and the infrared absorption peak of Si (Al)–O at 1116 cm−1 disappeared. The TG curves did not show a mass increase. Moreover, the initial reaction temperature of immersed coal was 39 °C lower than that of raw coal, and the heat release increased by 127.3 J g−1. The gas products in the samples varied mainly in quantity but not in species. MS and FTIR analyses revealed that SO2 was the main gas produced, and the maximum SO2 gas evolution temperatures of both coal samples were similar to the peak temperatures in the differential thermogravimetry and differential scanning calorimetry (DSC) curves. Furthermore, the infrared 3D spectrogram revealed that gas generated by immersed coal was detected at a lower temperature, the peak temperature occurred earlier, and the evolved intensity was stronger.

Effects of post-thermal treatments of ball-milled boron nitrides on solid base catalysis

Abstract Ball-milled hexagonal boron nitride was investigated as a solid base catalyst. The ball-milled boron nitrides were heated in a vacuum or air and used for Knoevenagel condensation. Measurements by X-ray diffraction, nitrogen adsorption, thermogravimetry-mass spectrometry, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy indicated that the heat treatment under vacuum hardly changed the physicochemical properties including crystal structure and surface composition whereas the heat treatment in air significantly altered the properties due to the formation of B2O3. The number of basic sites increased with the increase of the evacuation temperature. The boron nitrides after evacuation gave moderate product yield for Knoevenagel condensation of benzaldehyde with malononitrile at 40 °C. The boron nitrides after calcination showed different activity, dependent on the calcination temperature. The boron nitride after ball-milling, followed by calcination at 300 °C exhibited the highest activity. The catalytic activity was not directly related to the base amount and the surface areas, suggesting that acid-base bifunctionality plays an important role in Knoevenagel condensation using the ball-milled boron nitride catalysts.

Thermogravimetric Evolved Gas Analysis and Microscopic Elemental Mapping of the Solid Electrolyte Interphase on Silicon Incorporated in Free-Standing Porous Carbon Electrodes.

Free-standing electrodes, which are free from additives (binders and conductive agents) and even current collectors, are useful in terms of both application research and fundamental study. Here, we demonstrate the preparation of binder-free monolithic carbon electrodes embracing Si nanoparticles in their well-defined porous scaffolds via the one-pot sol-gel reaction followed by carbonization. The free-standing electrodes with a thickness of 150 μm work out as a high-areal-density anode for Li-ion batteries, delivering up to ca. 7 mA h cm-2. As the Si content increases, the capacity decay on cycling becomes pronounced, which is likely to associate with the fracturing and pulverization of Si nanoparticles even with the size smaller than 100 nm after long-term cycles. The thermogravimetry-mass spectrometry profile of the cycled electrode corroborates the successive electrolyte decomposition to grow solid electrolyte interphase (SEI) mainly composed of lithium alkylcarbonates, polymeric species, and LiF, rendering the electrode mass nearly double of its original state after 200 cycles. The elemental mapping analysis reveals that LiF is generated inhomogeneously in the monolithic electrodes unlike the other SEI components, resulting in the concentration gradient depending on the distance from a Li counter electrode.

Nitrogen‐doping microporous adsorbents prepared from palm kernel with excellent CO2 capture property

In post‐combustion CO2 capture, waste biomass is a favourable precursor to prepare porous carbons due to its low cost, renewability, and unique microstructures. This study presents a facile method for preparing N‐doping porous carbons. Palm kernel shell was selected as carbon precursor, and its inherent silica species acted as a natural template to form hierarchical pores. The obtained samples exhibit predominant characteristics with highly developed micropores and a high N content providing an important contribution to CO2 adsorption capacity, which can reach up to 5.29 and 2.30 mmol/g under 100 kPa at 25 and 60 °C, respectively. Moreover, the resultant porous carbons also exhibit excellent cycling stability after 20 cycles. Furthermore, the activation mechanism was investigated by the quantitative thermogravimetry‐mass spectrometry (TG‐MS) method.

Alumina nanoparticles as formaldehyde scavenger for urea-formaldehyde resin: Rheological and in-situ cure performance

Formaldehyde emission in the environment from thermosetting resins, like urea-formaldehyde (UF), is one of the most negative aspects of wood-based composite panels. UF resins with low or zero formaldehyde emission and keeping or improving their remarkable properties have been designed by different approaches, with special attention to organic and inorganic nanofillers. Although formaldehyde emission can be mitigated, controlling of rheology kinetics, curing and thermal stability are essential to avoid restrictions for practical applications. Here, we investigated the incorporation of small percentages of Al2O3 nanoparticles into UF resin regarding its rheology, thermodynamic mechanics, thermal kinetics and morphology. Changes on formaldehyde emission was determined by desiccator method and qualitatively illustrated by thermogravimetry-mass spectrometry analysis. The Al2O3 incorporation without significant agglomerations changed the viscosity of UF resin, presenting a shear thinning behavior, especially for higher quantity of nanoparticles. Likewise, analysis of thermodynamic mechanisms shows Al2O3 as an effective additive for UF resin without changing important curing parameters like vitrification point and gel temperature. Al2O3 nanoparticles are also effective to reduce the formaldehyde emission during the UF resin cure reactions at high temperatures and up to 14% in MDF composite panels at environmental temperatures.

Solid Polymer Electrolytes for Lithium Metal Battery via Thermally Induced Cationic Ring-Opening Polymerization (CROP) with an Insight into the Reaction Mechanism

We report the synthesis of solid polymer electrolytes (SPEs) using a thermally induced and a lithium salt catalyzed cationic ring-opening polymerization (CROP) technique. A synergistic approach using two salts such as lithium tetrafluoroborate-LiBF4 and lithium bis(trifluoromethane sulfonyl)imide-LiTFSI has assured a complete monomer to polymer conversion and fast reaction kinetics during the CROP process. The initiation mechanism of lithium salt-induced CROP is elucidated using molecular dynamic simulation, quantum chemical calculation, real-time FT-Raman spectroscopy, nuclear magnetic resonance spectroscopy, X-ray photoelectron spectroscopy, and thermogravimetry–mass spectrometry analysis techniques. The cross-linked 3D network of ethylene oxide based SPE is prepared without the use of any solvents or external catalysts. In particular, a mixture of poly(ethylene glycol) diglycidyl ether, LiBF4, and LiTFSI in appropriate proportions after a baking process produced a freestanding, flexible, and nontacky film. The synthesized SPEs exhibit low glass transition temperature (< −50 °C), high ionic conductivity (>0.1 mS cm–1), and excellent oxidation stability (>5.5 V vs Li/Li+). The SPE is polymerized directly onto a carbon-coated LiFePO4 cathode film and successfully cycled in a lithium metal battery configuration at 40 and 60 °C. As evidence, the SPE is galvanostatically cycled against a high-voltage LiNi1/3Mn1/3Co1/3O2 cathode, and the preliminary results indicated exciting characteristics in terms of specific capacity and Coulombic efficiency.

Insight into the catalytic thermal decomposition mechanism of ammonium perchlorate

Copper oxide (CuO) is an attractive burn rate modifier for composite solid propellant based on ammonium perchlorate (AP). However, the mechanism of catalytic decomposition of AP in the presence of CuO is still uncertain. Amount of gaseous products at various decomposition temperatures of AP in the presence and absence of CuO is lacking. Herein, a systematic study using thermogravimetry-mass spectroscopy (TG-MS) was carried out to evaluate the effect of CuO on AP decomposition mechanism. A novel hydrothermal method was reported for the preparation of nanosized copper oxide. The conversion of precursor Cu(NO3)2·3H2O to intermediate Cu2(NO3)(OH)3 was accomplished by in situ carbonization of small quantity of cotton fiber in the hydrothermal reaction chamber. pH of the reaction medium was controlled by utilizing the nitric acid in the reaction medium by in situ carbonization of cotton. This synthetic method aimed to minimize the shape-controlling agents and strong alkali for controlling the pH of the reaction medium for the preparation of catalyst grade CuO. Evolved gas analysis of AP decomposition products by TG-MS showed increased oxygen, chlorine and nitrogen evolution and decreased ammonia evolution in the presence of CuO, compared with that of AP without catalyst. This confirmed the enhanced interaction of ammonia and perchloric acid; the initial decomposition products of AP; and their further reaction in the presence of CuO. The change in composition of volatile products indicates change in mechanism of AP decomposition from proton transfer to electron transfer in the presence of CuO.

Acid mine drainage sludge as an alternative raw material for M-type hexaferrite preparation

Two types of dewatered acid mine drainage sludge were sampled from abandoned Japanese mines. The sludge shows great potential to be completely reused as alternative iron and calcium sources to synthesize M-type calcium substituted barium hexaferrite with addition of BaCO3 by solid-state reaction. The precursors and as-prepared samples were investigated by X-ray diffraction (XRD), field-emission scanning electron microscopy, and thermogravimetry–mass spectroscopy. The effect of sludge addition on phase formation and microstructure evolution during calcination was discussed in details. For sludge content up to 93.9 mass % with addition of 6.1 mass % BaCO3, M-type hexaferrite can be identified in the XRD patterns of as-prepared samples calcined at 1100, 1200, and 1300 °C. The impurities in the sludge, such as silicon, and aluminum, result in formation of secondary aluminosilicates phases; another impurity sulfur in the sludge may increase M-type hexaferrite formation temperature owing to barium or calcium sulfate formation in the precursor. The impurities also contribute to the difference in the microstructure for lower melting point. Possible applications of the sludge-derived hexaferrite products such as magnetic material or microwave absorber are suggested.

Elucidating the thermal degradation of carbazole‐containing platinum–polyyne polymers

ABSTRACTIn this article, we present the significant influence of the substitution pattern of carbazole on the thermal stability of carbazole‐containing platinum(II)–polyyne polymers. A series of the studies on the dynamic and isotherm conditions revealed a better thermal stability for the 3,6‐carbazole based platinum(II)–polyyne polymer (36CbzPtP), where alkynes were located at the p‐phenylene positions relative to the carbazole nitrogen atom, compared to that for the 2,7‐carbazole based counter polymer (27CbzPtP), where the alkynes were located at the m‐phenylene positions relative to the carbazole nitrogen atom. On the other hand, the thermogravimetry–mass spectrometry–Fourier transform infrared technique applied to the two polymers revealed the same degradation mechanism, which probably involved the thermal decomposition of triethyl phosphine moieties and which was followed by the CC scission of hexadecyl chains. The carbazole moieties eventually underwent degradation when the temperature exceeded 415 °C. Molecular modeling showed that polymer 27CbzPtP formed a linear structure, whereas polymer 36CbzPtP adopted a curved structures; this led to different packing modes of the polymer chains. This structural difference affected the efficiency of the initial degradation event of the triethyl phosphine groups. The curved structures of 36CbzPtP sterically protected the triethyl phosphine groups; this led to an increased thermal stability over that of 27CbzPtP. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47639.

Lithium Insertion Mechanism in Iron Fluoride Nanoparticles Prepared by Catalytic Decomposition of Fluoropolymer

Metal fluorides with high redox potential and capacity from strong metal–fluoride bond and conversion reaction make them promising cathodic materials. However, detailed lithium insertion and extraction mechanisms have not yet been clearly understood and explained. Here we report low-temperature synthesis of electrochemically active FeF3/FeF2 nanoparticles by catalytic decomposition of a fluoropolymer [perfluoropolyether (PFPE)] using a hydrated iron oxalate precursor both in air and in inert atmosphere. Freshly synthesized FeF3 nanoparticle delivered specific capacity above 210 mAh/g with decent cycling performance as a Li-ion battery cathode. Both in situ and ex situ characterization techniques were used to investigate the detailed PFPE decomposition and fluorination mechanisms leading to FeF3/FeF2 formation as well as the lithium insertion mechanism in a FeF3 cathode. Specifically, a detailed understanding was investigated using thermogravimetry–mass spectroscopy, X-ray diffraction, Fourier-transform in...

Poly(methyl methacrylate) nanocomposites involving aromatic diboronic acid

In this work, poly(methyl methacrylate), PMMA, composites involving various amounts of aromatic diboronic acid, BDBA, in the absence and presence of organically modified montmorillonite, Cloisite 30B, C30B, were prepared and characterized by X-ray diffraction, transmission electron microscopy, thermogravimetry, and direct pyrolysis mass spectrometry analyses. Morphologic analyses indicated homogenous dispersion of additives in PMMA matrix. Increase in thermal stability of PMMA was observed as the amount of BDBA incorporated into polymer matrix was increased. Strong evidences for interactions between the hydroxyl groups of diboronic acid and the ester groups of PMMA were detected. The increase in thermal stability was associated with these reactions producing also a cross-linked structure.

Thermal degradation of formamidinium based lead halide perovskites into sym-triazine and hydrogen cyanide observed by coupled thermogravimetry-mass spectrometry analysis

The thermal stability and decomposition products of formamidinium, a widely used organic cation in perovskite solar cell formulation, were investigated.

Thermal degradation study of vegetable tannins and vegetable tanned leathers

In this study, hydrolyzable tannins (commercial chestnut, valonea and tara extracts), condensed tannins (commercial quebracho and mimosa extracts) as well as calf leathers produced using these vegetable tanning agents were characterized by thermal decomposition methods using slow and high heating rates. Calf gelatin obtained by heating calf pelt in water at 70 °C was chosen as a reference material. Thermogravimetry/mass spectrometry (TG/MS) and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) experiments were performed on the tannin and leather samples. The evolution profiles of the decomposition products as well as the thermal stability of tannins and leathers were studied by TG/MS. A net difference was observed in the thermal behavior of hydrolyzable and condensed tannins. The condensed tannins produced the highest char yield, while the hydrolyzable tara extract released the most volatile products. The tannins of higher reactivity produced more stable leathers as it results from their higher decomposition temperature. The composition of both vegetable tanned leathers and vegetable tanning agents was characterized by the pyrolysis product distribution measured by Py-GC/MS method. Resorcinol and its methylated derivative (orcinol) were found to be a characteristic decomposition product for both condensed tannins, i.e. mimosa and quebracho. They were identified among the pyrolysis products of the mimosa and quebracho tanned leathers, as well.

Iron(III) β-diketonates: CVD precursors for iron oxide film formation

Complexes [Fe(β-diketonate)3] (β-diketonate = 2-acetylcyclopentanoate (3a), = 2-acetylcyclohexanoate (3b), = 4,4-dimethyl-1-phenyl pentanedionate (3c)) were synthesized by the reaction of FeCl3 with the respective β-diketones in presence of NaOH. The molecular structures of 3a and 3c in the solid state are discussed, confirming an octahedral coordination sphere at Fe(III) setup by the three bidentate-bonded β-diketonato ligands. Variation of the β-diketonato ligands allowed to influence the thermal behavior and vapor pressure of the complexes. TG-MS ( = Thermo Gravimetry-Mass Spectrometry) studies, exemplarily carried out on 3a, confirmed the release of the β-diketonate ligands. Complexes 3a–c were applied as MOCVD (=Metal-Organic Chemical Vapor Deposition) precursors for the deposition of Fe2O3 thin films on silicon substrates. It was found that with 3a,b, conformal and dense carbon-free γ- and α-Fe2O3 layers were produced at 450 °C, which was verified by scanning electron microscopy, energy dispersive X-ray spectroscopy and X-ray photon spectroscopy.

Chemical structure and gas products of different rank coals during pyrolysis

In this study, three coal samples (long flame coal/LFC, coking coal/CC, and anthracite/AC) from the same coal seam in Huaibei coalfield were simulated using in-situ Fourier transform infrared spectroscopy (FTIR) and thermogravimetry/mass spectrometry (TG/MS), respectively. The results show that with increasing coal rank, the Vdaf contents and atomic H/C and O/C ratio values of three coal samples decrease, but their calorific values increase. The absorption vibration peaks of main functional groups such as hydroxyl (–OH), aliphatic hydrocarbon (–CH2 and –CH3), aromatic hydrocarbon (C=C and CH), and oxygen-containing functional groups (C=O, C–O, and–COOH) can be observed in the infrared spectrum of three coal samples. Through the change curves of AI (Aromaticity index), CI (Condensed index of aromatic structure), and OMI (Organic maturity index) values with the final temperature of pyrolysis, there are differences in the main functional groups of three coal samples during the pyrolysis reaction. The initial temperature and the maximum mass loss rate temperature increase correspondingly as coal rank increases, but the mass loss difference and maximum mass loss rate decrease significantly. With the increase of coal rank, the initial temperature of small molecule gas (water (H2O), carbon dioxide (CO2), methane (CH4), and hydrogen (H2)) during coal pyrolysis is gradually higher. For each kind of small molecule gas, its maximum release can be affected by coal rank.

Study of co-pyrolysis of olive kernel with waste biomass using TGA/DTG/MS

The evolution of the pyrolysis products of olive kernel, a municipal solid waste fraction and a sewage sludge was analyzed qualitatively and quantitatively, using a properly developed and calibrated system of coupled thermogravimetry-mass spectrometry (TG/MS). The TG/MS profiles of the volatile products were also related to the pyrolysis thermograms, after their deconvolution which was performed using an independent parallel reaction kinetic model. The results from the co-pyrolysis of two mixtures of olive kernel with the municipal waste fraction and with sewage sludge at 7:3 mixing ratio revealed strong synergy effects on the production of CO up to 600 °C and the production of H2 at elevated temperatures. Other compounds were found to present slight synergistic (hydrocarbons up to C3, HCl, HCN) or additive behavior (CO2, H2O, NH3). No significant effect of co-pyrolysis on the anticipated quantities of char, tar and on the heating value of the pyrolysis gases of the mixtures was observed.

A novel route to the synthesis of H-ZSM-5-supported MoP and Ni2P phosphides

In this work, we report a novel synthesis of H-ZSM-5-supported MoP and Ni2P phosphides. The current approach uses a cinnamic strong alkali anion exchange resin (D201) as a reductant instead of H2 and employs an inert gas as a feed gas. The formation mechanism was proposed by thermogravimetry-mass spectrometry (TG-MS) and X-ray diffraction (XRD). D201 resin is carbonized to produce C and H2, and a small portion of Mo/Ni and POx species are firstly reduced by H2 and then the rest of the metal and POx species are reduced by C, to produce MoP/Ni2P on the H-ZSM-5, with the release of H2O, CO and CO2.

A review on thermal analyses of cyclodextrins and cyclodextrin complexes

Cyclodextrins are valuable natural or synthetically modified cyclic oligosaccharides that are widely used for ameliorating properties of biologically active compounds such as food additives and ingredients or medicinal compounds. They protect these compounds against light and oxidative degradation and provide host–guest supramolecular complexes having controlled release properties by molecular encapsulation, enhancing the water solubility and bioavailability. Among many characterization methods that are applicable in both solution and solid state, thermal techniques were widely used for analysis and stability evaluation of cyclodextrins and cyclodextrin complexes. This updated review deals with the use of thermal methods for analysis of cyclodextrins and cyclodextrin complexes. Classical and modern thermal techniques used for evaluation of inclusion compound formation were reviewed. Special attention was gave for thermogravimetry–differential thermogravimetry, differential thermal analysis, differential scanning calorimetry, hot stage microscopy, as well as for the more recent techniques thermogravimetry–mass spectrometry, gas chromatography-time-of-flight-mass spectrometry and isothermal titration calorimetry. In order to evaluate the cyclodextrin complexation capability by thermal methods, we grouped for the first time the guest compound as drugs by anatomical therapeutic chemical classification (ATC), as well as odorants, essential oils and vegetable extracts, antioxidants, fatty acids, oils, fatty acid-based derivatives, other organic, organometallic and inorganic compounds. The formation of cyclodextrin inclusion complexes was emphasized by disappearance of the signal corresponding to the melting or boiling points of the guest compound and the behavior of the hydration water molecules in the complex in comparison with the raw host and guest compounds. The thermal stability of the guest compound after cyclodextrin complexation was also discussed. It was emphasized that thermal methods are some of the most valuable techniques for analyzing cyclodextrin complexes and together with other methods can complete the information related to the host–guest molecular inclusion process and the specific properties of these cyclodextrin complexes.

Solvent-Assisted Stepwise Redox Approach To Generate Zeolite NaA-Supported K2O as Strong Base Catalyst for Michael Addition of Ethyl Acrylate with Ethanol.

Solid base catalysts featuring green, robustness, and high activity play an important role in the current fine-chemical and petrochemical industry. Normally, the generation of supported K2O by thermal decomposition of KNO3 requires high temperature, and this process can sometimes destroy the structure of supporting materials. We herein report a solvent-assisted stepwise redox (SASR) approach to generate zeolite NaA-supported K2O, which we call K2O/NaA, that function as the solid base catalyst for Michael addition reaction between ethanol and ethyl acrylate. The solvent-assisted redox decomposition process of KNO3 at elevated temperature was investigated by thermogravimetry–mass spectrometry. It reveals that after reducing a minor amount of KNO3 at 400 °C, the organic solvent decomposes to form carbon, which promotes the reduction of KNO3 to generate strong basicity on the zeolite NaA at 600 °C. The resulting material, K2O/NaA-S, exhibits improved catalytic activity in Michael addition reaction over other benchmark base catalysts that have been used in this reaction. This catalyst is durable for at least four catalytic cycles without apparent loss in activity. K2O/NaA-S exhibits larger reaction rate constant yet lower activation energy than K2O/NaA prepared by thermal decomposition method. The SASR approach described in this paper represents a new blueprint for the generation of the supported alkali oxide as the solid base catalyst.

Carbon-containing gaseous pollutants emission characteristics during municipal sewage sludge combustion and pyrolysis with TG-MS technique

In this study, the carbon-containing gaseous pollutants emission characteristics during municipal sewage sludge combustion and pyrolysis were investigated by using simultaneous thermogravimetry-mass spectrometry (TG-MS) method. The results indicated that the sewage sludge possesses different devolatilization characteristics in the terms of mass loss and gas evolution. The main decomposition of sewage sludge during the combustion process was divided into four stages, and only first three ones existed during sludge pyrolysis. The evolved carbon-containing gaseous products (CO2 and light hydrocarbons) emission behaviours during combustion and pyrolysis were different. This research provided basic data support and background knowledge for municipal sewage sludge thermal disposal and fuel gas treatment, which could help to control the gaseous pollutants during sewage sludge thermal treatment.