TG MS Research Articles

Gasification of pyrolysis chars from sewage sludge

Gasification of char derived from sewage sludge was studied by using the TG–MS system. Experiments were carried out at different temperatures and steam concentrations. The temperatures of 700–900°C were necessary to complete the conversion in reasonable time. Three reaction rate models for gas–solid reaction were applied to describe the effect of char conversion on the reaction rate. In comparison to the shrinking core model for reaction-controlled regime and random pore distribution models, simple pseudo-homogeneous first-order kinetics was found to be the best for predicting the rate of char steam gasification. Kinetic parameters estimated from the experimental data are in accordance with the literature for lignocellulosic char gasification and are the first ones published for sewage sludge char gasification.

Reproducibility of preparation of cellulose-based cryogels characterised by TG–MS

A TG–MS analysis was applied to reveal the reproducibility of preparation of cellulose-based cryogels. The cellulose materials were obtained by dissolution of cellulose in melted Ca(SCN)2, followed by gelation and regeneration in an ethanol bath and dried by lyophilisation. The whole preparation process was repeated 14 times. The pyrolysis of the prepared samples was investigated by TG–MS. A number of parameters were determined from the obtained TG, DSC and MS curves and statistically analysed. TG and MS data together with estimated reactions which occurred during sample decomposition enable the calculation of the composition of cryogels and pyrolysed material. An unexpected amount of calcium thiocyanate was found in cellulose cryogels (about 31 %) and after pyrolysis, a high content of calcium oxide (about 58 %) as a product of calcium thiocyanate decomposition was calculated for the final material. The total yield of carbon from cellulose decomposition was about 12 %. From the obtained data, it could be concluded that the preparation of cellulose cryogels is well reproducible if the amounts of the initial substances are kept constant.

Comprehensive characterization of thermal decomposition of sewage sludge by TG–MS

Based on results of sewage sludge pyrolysis performed in a thermo-balance coupled with mass spectrometer (TG-MS) and elemental analysis of the substrate and solid residue a new integrated approach for quantification of yields and composition of the products was proposed. The TG-MS measurement enables to obtain the yield of oil and tars. Additionally employing the elemental analysis an approximate composition of liquid product can be also calculated. To obtain more detailed information on the mechanism of pyrolysis deconvolutions of DTG curve and profiles of evolved product into eight groups of reaction occurring at different temperature regions were performed. The proposed method can be also used for studying gas–solid reactions where CO, CO2, H2 and H2O are the main gaseous components (e.g. catalyst reduction, water–gas shift reaction etc.).

Synthesis and characterization of dimeric and square-shaped dicarboxylate-bridged dimolybdenum(II) coordination compounds

The reaction of 1equivalent of the dimolybdenum(II) complex [Mo2(NCCH3)10][BF4]4 (1) with tetrabromoterephthalic acid (0.5equiv.) in acetonitrile or propionitrile affords the dimeric dicarboxylate-bridged complexes [(CH3CN)8Mo2(OOC-C6Br4-COO)Mo2(NCCH3)8][BF4]6 (2) and [(CH3CH2CN)8Mo2(OOC-C6Br4-COO)Mo2(NCCH2CH3)8][BF4]6 (3), respectively. The molecular square [(CH3CN)6Mo2(OOC-C4H2S-COO)]4[BF4]8 (4) can be isolated by reacting [Mo2(NCCH3)10][BF4]4 (1) (1equiv.) with 2,5-thiophenedicarboxylic acid (1equiv.) in acetonitrile. The isolated coordination compounds 2–4 are characterized by NMR spectroscopy (1H, 11B, 13C{1H}, 19F), IR spectroscopy, elemental analysis, TG–MS measurements and UV–Vis spectroscopy. The molecular structures of compounds 2 and 4 are determined by X-ray single crystal diffraction.

Preparation and characterization of activated carbon from reedy grass leaves by chemical activation with H3PO4

Activated carbons were produced from reedy grass leaves by chemical activation with H3PO4 in N2 atmosphere and their characteristics were investigated. The effects of activation temperature and time were examined. Adsorption capacity was demonstrated with BET and iodine number. Micropore volume and pore size distribution of activated carbons were characterized by N2 adsorption isotherms. The surface area and iodine number of the activated carbons produced at 500°C for 2h were 1474m2/g and 1128mg/g, respectively. Thermal decomposition of pure reedy grass leaves and H3PO4-impregnated reedy grass leaves have been investigated with thermogravimetric/mass spectroscopy (TG–MS) technique. It was found that the temperature and intensity of maximum evolution of H2O and CO2 of H3PO4-impregnated reedy grass leaves were lower than that of pure reedy grass leaves. This implies that H3PO4 as an activating reagent changed the thermal degradation of the reedy grass leaves, stabilized the cellulose structure, leading to a subsequent change in the evolution of porosity. The results of X-ray photoelectron spectroscopy and Fourier-infrared spectroscopy analysis indicate that the produced activated carbons have rich functional groups on surface.

Using TG–FTIR and TG–MS to study thermal degradation of metal hypophosphites

Three typical metal hypophosphite flame retardants La(H2PO2)3·H2O (LHP), Ce(H2PO2)3·H2O (CHP), and Al(H2PO2)3 (AHP) were synthesized and characterized by Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction, scanning electron microscopy, thermogravimetric analysis (TG), derivative thermogravimetric analysis, and differential thermal analysis. The thermal degradation products from the synthesized metal hypophosphites were also investigated using thermogravimetry coupled with Fourier transform infrared spectroscopy (TG–FTIR) and thermogravimetry coupled with mass spectrometry (TG–MS). The synthesized metal hypophosphites were also used as flame retardants for poly (1,4-butylene terephthalate) (PBT), and the combustion properties of flame-retarded PBT were evaluated using the limiting oxygen index and UL-94 tests. The results showed that the metal hypophosphites LHP, CHP, and AHP can be used as effective flame retardants for PBT, and these compounds can be obtained through a simple precipitation method. TG–FTIR and TG–MS results showed that the degradation process of AHP involves two steps, corresponding to the removal PH3 reaction and the further dehydration reaction of the hydrogen phosphate aluminum. While LHP and CHP have three degradation steps, the additional step is due to that LHP and CHP which will loss the crystal water at lower temperature.

Synthesis and thermal decomposition of new compound containing Bi(III) complex and 4-toluenesulfonate

An investigation of the interaction of Bi(III) with an aqueous solution of p-toluenesulfonic acid at 70°C is performed. As a result, a new composition [Bi6O6(OH)3](C7H7SO3)3 is precipitated. Thе product synthesized is characterised by various methods: elemental analysis, FTIR, DTA, TG–MS, and powder X-ray diffraction. The symmetry – orthorhombic F222 space group, and unit cell parameters: a=9.8056Å, b=17.1970Å and c=39.256Å are determined. Based on the experimental results, X-ray diffraction indexation, as well as thermal decomposition products of the compound are suggested.

TG–MS analysis of thermal behavior and gaseous emissions during co-combustion of straw with municipal sewage sludge

The thermal behavior and gas product distribution during combustion of straw (wheat straw, corn stalks, and cotton stalks), municipal sewage sludge (MSS), and their blends were investigated by thermogravimetry–mass spectroscopy. The experiments were conducted with various blending ratios and temperatures ranging from 323 to 1,173 K. Addition of MSS decreased the combustion performance of the straw. The reactions between wheat straw and corn stalks with MSS proceeded more easily than that of cotton stalks. Significant interactions were observed between the straw and MSS at the char combustion stage. Gaseous species (CO2, SO2, NH3, HCN, and NO) were mainly produced at temperatures of 523–873 K at which most of the mass loss occurred. Higher MSS proportions in the blends resulted in lower emissions peaks for CO2, NH3, HCN, and NO except for SO2. To ensure combustion performance and mitigate problematic gaseous emissions, the proportion of MSS added to the blends should be <30 mass%.

Partial coal pyrolysis and its implication to enhance coalbed methane recovery, Part I: An experimental investigation

This paper examines the feasibility of combining a process known as enhanced methane recovery with partial coal pyrolysis to improve the petrophysics of coal seams and ultimately extract higher methane yields with accompanying pyrolysis gases. Partial pyrolysis for coal gas generation changes the pore and fracture structure, which in turn affect the permeability. A series of laboratory experiments on three coal rank samples monitored the changes in pore structure and permeability accompanying coal pyrolysis. Thermogravimetry–mass spectrometry (TG–MS) analysis evaluated mass loss and product composition. The pore and fracture structure evolution was determined by a combination of mercury intrusion porosimetry (MIP), scanning electron microscope (SEM) and methane adsorption capacity measurements on heat-treated coal blocks of ∼100g. The pore volume and methane adsorption capacity of LRC specimen (0.56% Ro,m) with 10°C/min and a hold time of 30min experienced slight changes during the heating process from 25°C to 400°C, but when heated from 400°C to 800°C, the pore volume in the LRC specimen greatly increased and the mercury-determined total porosity went from 36% at 400°C to 43% at 800°C. The permeability of the specimens at the temperature range of 300–400°C increased exponentially with temperature due to the generated pore–fracture system. The sample LRC (800°C) with the highest mercury-determined pore volume possessed the lowest methane capacity (19.45cm3/g) due to the maximum adsorption volume of pyrolyzed coal obtained from the Langmuir model was related not only to the pore structure but also to the extent of graphitization. Therefore, they may have significant implications for enhanced coalbed methane (CBM) recovery.

Synthesis of Highly Dispersed Ruthenium Nanoparticles Supported on Activated Carbon via Supercritical Fluid Deposition

Highly dispersed ruthenium (Ru) nanoparticles supported on activated carbon (AC) were controllably synthesized by supercritical fluid deposition (SFD). The Ru nanoparticles prepared by SFD presented a smaller mean particle size than particles prepared by the ethanol impregnation method. The effects of temperature, pressure, and Ru loading on catalyst preparation were systematically investigated. As any one of above parameters increased, Ru mean particle sizes always decreased first and then increased. The smallest mean particle size (1.6 nm) was obtained at Ru loading of 2%, 45 °C, and 10 MPa. On the scale of Ru mean particle size from 1.6 to 3.9 nm, the catalysts with smaller Ru mean particle size presented higher catalytic activity. The interactions between the Ru precursor and AC were characterized by TG–MS, TPR, and FTIR spectroscopy. The results obtained have revealed the reduction of the carbonyl (C═O) in Ru precursors after depositing on AC with the aid of SCCO2.

Novel ethylenediamine-gallium phosphate containing 6-fold coordinated gallium atoms with unusual four equatorial Ga–N bonds

A novel ethylenediamine-gallium phosphate, formulated as Ga(H2NCH2CH2NH2)2PO4·2H2O, was synthesized under hydrothermal conditions. The crystal structure, including hydrogen positions, was determined using single-crystal X-ray diffraction data (monoclinic, a=9.4886(3)Å, b=6.0374(2)Å, c=10.2874(3)Å, and β=104.226(3)°, space group Pc) and the bulk was characterized by chemical (Ga–P–C–H–N) and thermal analysis (TG–MS and DSC), including activation energy data of its thermo-oxidative degradation, powder X-ray diffraction (PXRD), solid-state nuclear magnetic resonance (SS-NMR) measurements, and transmission electron microscopy (TEM, SAED/NBD, and STEM BF-EDX). The crystal structure is built up of infinite zig-zag chains running along the c-axis, formed by vertex-shared {PO4} and {GaO2N4} polyhedra. The new compound is characterized by unusual four equatorial Ga–N bonds coming from two nonequivalent ethylenediamine molecules and exhibits strong blue emission at 430nm (λex=350nm) in the solid state at room temperature.

Organic xerogels based on condensation of different m-substituted phenols with formaldehyde

Four samples of organic xerogels have been prepared by polycondensation of different m-substituted phenols (3-aminophenol, m-cresol, phenol and resorcinol) with formaldehyde and subsequent drying. From the set of tested solvents, n-butanol has been chosen as the most suitable one. The reactivity of the m-substituted phenols was ascertained in the order phenol < m-cresol < resorcinol < 3-aminophenol. Phenol and m-cresol did not completely react with formaldehyde during polycondensation reactions. The used type of m-substituted phenol strongly influenced the properties of the final material (the appearance of the organic xerogels, the values of densities and shrinkage after drying, the amount of humidity released during drying and the carbon yield after pyrolysis). The pyrolytic process has been evaluated by TG–MS as three-step process. The first step was characterised as volatile substances loss (n-butanol and water) and mostly CO2 evolution, the second step as evolution of the rest volatiles and the beginning of the carbonisation processes, whilst during the third step merely carbonisation reactions occurred. On the basis of all considered results, 3-aminophenol has been evaluated as the most appropriate precursor for carbon xerogel preparation. It is cheap and the most reactive; it exhibited the lowest values of density, shrinkage and humidity content as well as relatively high carbon yield.

Thermal stabilities and decomposition mechanism of amino- and hydroxyl-functionalized ionic liquids

Thermal stabilities and thermal decomposition mechanisms of amino-functionalized ionic liquid (IL) 1-aminoethyl-3-methylimidazolium bromide ([C2NH2MIM][Br]) and hydroxyl-functionalized IL 1-hydropropyl-3-methylimidazolium chloride ([C3OHMIM][Cl]) were investigated by thermogravimetric analysis (TGA), TG–mass spectroscopy (TG–MS), density functional theory (DFT), and nuclear magnetic resonance (NMR) spectrum. Results show that the [C2NH2MIM][Br] and [C3OHMIM][Cl] are stable up to 200 °C and 220 °C, respectively. Also, DFT calculation indicates that the thermal decomposition mechanisms of [C2NH2MIM][Br] and [C3OHMIM][Cl] are complicated, while bimolecular nucleophilic substitution (SN2) is the main reaction mechanism. TG–MS and NMR spectra further prove the mechanisms.

Evolved gas analysis of coal-derived pyrite/marcasite

The products evolved during the thermal decomposition of the coal-derived pyrite/marcasite were studied using simultaneous thermogravimetry coupled with Fourier-transform infrared spectroscopy and mass spectrometry (TG-FTIR–MS) technique. The main gases and volatile products released during the thermal decomposition of the coal-derived pyrite/marcasite are water (H2O), carbon dioxide (CO2), and sulfur dioxide (SO2). The results showed that the evolved products obtained were mainly divided into two processes: (1) the main evolved product H2O is mainly released at below 300 °C; (2) under the temperature of 450–650 °C, the main evolved products are SO2 and small amount of CO2. It is worth mentioning that SO3 was not observed as a product as no peak was observed in the m/z = 80 curve. The chemical substance SO2 is present as the main gaseous product in the thermal decomposition for the sample. The coal-derived pyrite/marcasite is different from mineral pyrite in thermal decomposition temperature. The mass spectrometric analysis results are in good agreement with the infrared spectroscopic analysis of the evolved gases. These results give the evidence on the thermal decomposition products and make all explanations have the sufficient evidence. Therefore, TG–MS–IR is a powerful tool for the investigation of gas evolution from the thermal decomposition of materials.

Activation energy in the thermal decomposition of MgH2 powders by coupled TG–MS measurements

The catalytic effect of SnO2 doping on the hydrogen thermal desorption of MgH2 was investigated by coupled thermogravimetric–mass spectrometric (TG–MS) analyses, among a set of samples prepared with different SnO2/MgH2 molar ratios. A small release of water and carbon dioxide was detected at temperatures preceding to the reductive thermal decomposition of MgH2 yielding molecular hydrogen. While TG and DTA data collected at different heating rate provided an apparent activation energy for the entire thermal process, appropriate ion-current signals from the MS-data were used to obtain the activation energies of the single chemical reactions yielding the formation of H2O, CO2, and H2. The most common equations derived from model-free isoconversion methods (Kissinger–Akahira–Sunose; Flynn–Wall–Ozawa; Starink) were used by processing temperatures referred to the different kinds of signals (TG-, DTG-, DTA-, TIC-, molecular-ion IC-curves) for isoconversion points corresponding to the maximum rate of transformation. Temperature and activation energy values were used to compare the kinetic behavior of MgH2 powder with the best performance of a doped sample, prepared by high energy grinding of SnO2/MgH2 mixture. Doped-MgH2 samples prepared with SnO2 mass ratio of 0.2 showed the best kinetic thermal decomposition behavior, with respect to the pristine MgH2 powder: a decreasing of the main thermal decomposition event of ca. 51–57 °C associated to a coherent decreasing of ca. 20 % (ca. 30 kJ mol−1) of its activation energy value.

Activation energy in the thermal decomposition of MgH2 powders by coupled TG–MS measurements

Activation energy in the thermal decomposition of MgH2 powders by coupled TG–MS measurements

Intumescent Flame Retardancy and Thermal Degradation of Epoxy Resin Filled with Ammonium Polyphosphate Using Thermogravimetric Analysis–Fourier Transform Infrared Spectroscopy and Thermogravimetric Analysis–Mass Spectrometry

The flammability of epoxy resin (EP) and its composite with ammonium polyphosphate (EPAPP) was investigated with limiting oxygen index (LOI), UL 94, and cone calorimeter tests. A systematic and comparative evaluation of the thermal degradation of EP and EPAPP has been investigated using thermogravimetry coupled with Fourier transform infrared spectroscopy (TG–FTIR) and thermogravimetry coupled with mass spectrometry (TG–MS). The results showed that the flame retardant of ammonium polyphosphate (APP) can constitute an intumescent flame retardant (IFR) system with EP, and APP can effectively improve the LOI of EP; with 6 wt% addition level of APP, EPAPP can pass UL 94 V 0 test. The cone calorimeter test results showed that the flame retardancy and smoke suppression of EP were significantly improved by APP, and toxic gas products such as carbon monoxide and carbon dioxide obviously decreased. Thermogravimetry–Fourier transform infrared spectroscopy and TG–MS results showed that the degradation process of EP produces large amounts of gas products and mainly containing of water, carbon dioxide, methane, benzene and its derivatives, as well as phenol and its derivatives. Compared to EP, the kinds of decomposition products of EPAPP sample were not changed significantly, except that more ammonia gas was generated. For the EPAPP sample, the products of water, benzene, and phenol increased, whereas the carbon dioxide and the flammable hydrocarbon fragments CxHy decreased significantly during the decomposition.

Synthesis and thermal behaviors of 1,8-dihydroxy-4,5-dinitroanthraquinone barium salt

A novel energetic green combustion catalyst, 1,8-dihydroxy-4,5-dinitroanthraquinone barium salt (DHDNEBa), was firstly synthesized by the process of metathesis reaction with a yield of 95.7%, and its structure and thermal behavior were characterized by IR, elemental analysis, thermogravimetry analysis (TGA) and differential scanning calorimetry (DSC). The thermal decomposition kinetics and mechanism were studied by means of different heating rate DSC, thermolysis in situ rapid-scan FTIR and simultaneous TG–MS technology. The results show that the apparent activation energy and pre-exponential factor of the exothermic decomposition reaction of DHDNEBa obtained by Kissinger's method are 177.3kJmol−1 and 1013.5s−1. The entropy (ΔS≠), enthalpy (ΔH≠) and free energy of activation (ΔG≠) of the first step thermal decomposition are found to be 8.16Jmol−1K−1, 168.0kJmol−1 and 163.4kJmol−1, respectively. The self-accelerating decomposition temperature (TSADT) and critical temperature of thermal explosion (Tb) are 555.0 and 570.2K. The decomposition reaction process of DHDNEBa begins with four-molecule combined water lost in the DHDNEBa structure. The gaseous products such as H2O, CO, CO2 and NO are detected from decomposition of DHDNEBa at 606K. The residue is mainly composed of BaO and some carbon black. The above-mentioned information on thermal behavior is quite useful for analyzing and evaluating the stability and thermal safety of DHDNEBa.

Copper carboxylate with different carbon chain lengths as metal–organic decomposition ink

The copper carboxylates with different carbon chain length (glycolate, lactate and oleate) were used to prepare the metal–organic decomposition ink. TG–MS showed that copper carboxylates underwent a two-step thermal decomposition for the conversion to elemental copper, and the organic residues after decomposition is relevant with the carbon chain length. Conductive copper films were obtained by drop coating of a copper carboxylate solution onto a glass slide followed by sintering at different temperatures. Copper carboxylates with shorter carbon chain give better conductive films. Both copper glycolate and copper lactate films begin to show conductivity after sintered at 150 °C for 60 min under nitrogen. The resistivity of the copper features with 2 μm thickness of copper glycolate and copper lactate was 23.0 ± 2 and 44.0 ± 6 μΩ cm after sintering at 250 °C for 60 min under nitrogen, respectively, with the former being about 7.4 % of the conductivity of bulk copper. X-ray photoelectron spectroscopy results showed slight surface oxidation in the sintered copper feature from these copper carboxylates. Although the conductivity of the obtained copper film needs to be improved further, the method shows some advantages over the copper nanoparticles ink, such as avoiding tedious synthesis and protection of nanoparticles, low cost, etc.

TG–MS–FTIR (evolved gas analysis) of kaolinite–urea intercalation complex

The products evolved during the thermal decomposition of kaolinite–urea intercalation complex were studied by using TG–FTIR–MS technique. The main gases and volatile products released during the thermal decomposition of kaolinite–urea intercalation complex are ammonia (NH3), water (H2O), cyanic acid (HNCO), carbon dioxide (CO2), nitric acid (HNO3), and biuret ((H2NCO)2NH). The results showed that the evolved products obtained were mainly divided into two processes: (1) the main evolved products CO2, H2O, NH3, HNCO are mainly released at the temperature between 200 and 450 °C with a maximum at 355 °C; (2) up to 600 °C, the main evolved products are H2O and CO2 with a maximum at 575 °C. It is concluded that the thermal decomposition of the kaolinite–urea intercalation complex includes two stages: (a) thermal decomposition of urea in the intercalation complex takes place in four steps up to 450 °C; (b) the dehydroxylation of kaolinite and thermal decomposition of residual urea occurs between 500 and 600 °C with a maximum at 575 °C. The mass spectrometric analysis results are in good agreement with the infrared spectroscopic analysis of the evolved gases. These results give the evidence on the thermal decomposition products and make all explanation have the sufficient evidence. Therefore, TG–MS–IR is a powerful tool for the investigation of gas evolution from the thermal decomposition of materials and its intercalation complexes.