TG-FTIR Analysis Research Articles

Torrefaction of Rice Husk using TG-FTIR and its Effect on the Fuel Characteristics, Carbon, and Energy Yields

A torrefaction testing method using TG-FTIR is presented, ensuring accuracy of torrefaction temperature and time. Torrefaction experiments of rice husk were performed at different temperatures (200, 230, 260, and 290 °C) for 30 min. The effect of torrefaction on the fuel characteristics was studied. Yields of carbon and oxygen, as well as solid and energy, were also considered. TG-FTIR analysis showed that in the depolymerization stage of the torrefaction process, CO2 characteristic peaks appeared, while those of carbonyl compounds and aromatic hydrocarbons were weaker. In the devolatilization stage, the characteristic peaks of CO2 and H2O were significant. Meanwhile, carbonyl compounds, aromatic hydrocarbons, and phenols were gradually produced. After that, each absorption peak gradually became weaker. After torrefaction at 290 °C, more than 76.6% of energy was retained in torrefied rice husk, while the solid yield was only 65.6%. 1.8%~52.2% of oxygen in rice husk was released in the torrefaction temperature range of 200 °C to 290 °C. Torrefaction increased the heating value, reduced the oxygen content, and improved the storability, which indicates that torrefaction is an effective way to improve the properties of rice husk.

Roasting characteristics of specularite pellets with modified humic acid based (MHA) binder under different oxygen atmospheres

MHA (modified humic acid based) binder has been found as an effective substitution for bentonite in the pelletization of specularite concentrates. This study aimed to clarify the roasting behavior of specularite pellets with MHA binder under different oxygen atmospheres. The thermal behavior of the MHA binder was initially determined by TG-DSC, TG-FTIR and MRU gas analysis. The reducing gaseous products, such as CO and H2, affected the oxidation and consolidation of the specularite pellets with MHA binder due to the pyrolysis of organic matter in the MHA binder heated in air. The primary phase compositions of the specularite pellets with MHA binder roasted in N2 and 10% oxygen atmospheres were composed of hematite and magnetite, whereas there was only hematite in the pellet roasted in a 20% oxygen atmosphere. The images by optical microscopy and SEM further indicated that the oxygen content of the roasting atmosphere markedly influenced the microstructure feature of the specularite pellets with MHA binder.

The effect of metal oxide decorated graphene hybrids on the improved thermal stability and the reduced smoke toxicity in epoxy resins

Metal oxide decorated graphene hybrid materials, Co3O4–graphene and SnO2–graphene, were synthesized for improving the thermal stability and suppressing the smoke in combustion for epoxy resins. Incorporation of metal oxide/graphene hybrids leads to significant thermal stabilization: a 37 and 27 °C increment in the temperature of 5% mass loss is observed for SnO2–graphene/EP and Co3O4–graphene/EP, respectively, compared to that of pure EP. The barrier effect of graphene and the restricted mobility of the polymer chains by metal oxide are believed to be the crucial factor for improving the thermal stability. TG-FTIR analysis shows that the amount of organic volatiles of EP is significantly reduced and the toxic CO is suppressed after incorporating SnO2–graphene or Co3O4–graphene, impling the reduced fire hazards. The synergism between the catalysis effect of metal oxide and the adsorption effect of graphene is the possible mechanism for the smoke suppression.

Comparison of thermal behavior of natural and hot-washed sisal fibers based on their main components: Cellulose, xylan and lignin. TG-FTIR analysis of volatile products

Abstract This paper presents in a comprehensive way the thermal behavior of natural and hot-washed sisal fibers, based on the fundamental components of lignocellulosic materials: cellulose, xylan and lignin. The research highlights the influence exerted on the thermal stability of sisal fibers by other constituents such as non-cellulosic polysaccharides (NCP) and mineral matter. Thermal changes were investigated by thermal X-ray diffraction (TXRD), analyzing the crystallinity index (%Ic) of cellulosic samples, and by simultaneous thermogravimetric and differential thermal analysis coupled with Fourier-transformed infrared spectrometry (TG/DTA-FTIR), which allowed to examine the evolution of the main volatile compounds evolved during the degradation under inert and oxidizing atmospheres. The work demonstrates the potential of this technique to elucidate different steps during the thermal decomposition of sisal, providing extensible results to other lignocellulosic fibers, through the analysis of the evolution of CO 2 , CO, H 2 O, CH 4 , acetic acid, formic acid, methanol, formaldehyde and 2-butanone, and comparing it with the volatile products from pyrolysis of the biomass components. The hydroxyacetaldehyde detected during pyrolysis of sisal is indicative of an alternative route to that of levoglucosan, generated during cellulose pyrolysis. Hot-washing at 75 °C mostly extracts non-cellulosic components of low decomposition temperature, and reduces the range of temperature in which sisal decomposition occurs, causing a retard in the pyrolysis stage and increasing Tb NCP and Tb CEL , temperatures at the maximum mass loss rate of non-cellulosic polysaccharides and cellulose decompositions, respectively. However, enriching sisal fibers in cellulose produces a decrease of Tb CEL under an oxidizing atmosphere, and furthermore, a delay of the combustion process, displacing Tb COM to higher temperatures. The results and findings of the paper would help further understanding of thermal processes where Agave fibers are involved, as the decomposition of their composites.

Study on Volatile Evolution during the Eucalyptus Pyrolysis by Using TG-FTIR Analysis

In this study, thermogravimetric analysis coupled with Fourier transform infrared analysis (TG-FTIR) was used to studying the volatile evolution characteristic during the eucalyptus pyrolysis from South China. The thermogravimetric analysis results indicate that the pyrolysis of eucalyptus occurred in three main stages which are the moisture vaporization stage, the volatile matter release stage and the char decomposition stage. The major gases evolved during the pyrolysis process were identified to be H2O, CO, CO2, CH4. In addition, the effects of different heating rates on the emissions of these pyrolysis products have been studied.

TG-FTIR Measurement of CO2-H2O co-adsorption for CO2 air capture sorbent screening

Capturing atmospheric CO2 using solid sorbents is gaining interest. As ambient air normally contains much more (up to 100 times) water than CO2, a selective sorbent is desirable as co-adsorption will most likely occur. In this study, a convenient method based on an TG-FTIR analysis system is developed and used to characterize sorbents for their water and CO2 adsorption capacity when exposed to ambient air. The method allows to determine quantitatively the co-adsorbed amounts of CO2 and water from small sample sizes (10 mg range) and is expected to be a useful instrument in sorbent screening and evaluation

Characterization of thermally stable gamma alumina fibres biomimicking sisal

Mesoporous gamma alumina fibres of high surface area, stable up to 1000°C, were synthesized by bioreplica technique using sisal fibres as templates. Alumina formation during pyrolysis and calcination of fibres infiltrated with aluminium chloride solution has been studied, paying special attention to the interaction between the precursor and sisal fibres, using several experimental techniques such as ATR-FTIR, coupled TG-FTIR and thermo-XRD analysis. The morphology and microstructure of the resulting alumina fibres were characterized using SEM and TEM. The crystallographic analysis of the alumina sample performed by electron and X-ray diffraction suggests that fibres are constituted by η and γ-Al2O3 crystallites, whose chemical structure was confirmed by ATR-FTIR and Al27-MAS-NMR. The specific surface area and porosity of ceramic fibres were determined by N2 and CO2 adsorption–desorption measurements. Resulting alumina fibres retain high specific surface areas of 200 and 150m2/g even after calcination at 1000°C for 15h in dry air and for 4h in wet air, respectively.

Volatile Products Formed in the Thermal Decomposition of a Tobacco Substrate

The identification and quantification of volatile species formed in the thermal degradation of tobacco substrates was investigated by TG-FTIR analysis. A specific experimental methodology was developed to obtain quantitative data on key components of interest present in evolved gases during TG-FTIR runs in air and nitrogen at low heating rates. Multivariate deconvolution techniques were used to identify the contributions of the key components of interest to the overall FTIR spectra. Validation runs were carried out to test the limits of the TG-FTIR technique. Significant data were obtained for the quantitative characterization and the emission profiles of some key components of evolved gases, such as acetaldehyde, carbon dioxide, carbon monoxide, nicotine, and water. A different experimental strategy based on the use of a fixed bed reactor was applied to the characterization of glycerol evolved from the tobacco substrate, thus obtaining a complete figure of the main components of the evolved gases formed during the slow thermal decomposition of tobacco substrates in nitrogen and air.

Propeller-like heterotrinuclear CuII–LnIII–CuII compounds – Physicochemical properties

The new heterotrinuclear compounds [Cu2Ln(L)2(NO3)(H2O)2](NO3)2·3H2O (where Ln=Sm (1), Eu (2) and L=C19H18N2O4Br2 is the deprotonated form of N,N′-bis(5-bromo-3-methoxysalicylidene)propylene-1,3-diamine,) have been synthesized and characterized by FTIR, TG-FTIR, TG/DSC and single crystal X-ray analyses. The complexes of 1 and 2 are isostructural. In the trinuclear compounds two terminal copper(II) ions are coordinated by imino and phenolate oxygen atoms, whereas the central lanthanide(III) ion is bound to the phenolate and methoxy oxygen atoms of the Schiff base ligands. The first change in mass estimated from TG curve corresponds to the loss of water molecules. The decomposition of the Schiff base ligand starts above 200°C. The final decomposition solid products are CuO and Ln2CuO4. The TG-FTIR results show that the main gaseous products in whole decomposition process of complexes are water (H2O), carbon dioxide (CO2), carbon monoxide (CO), nitric oxides (NOx) and bromomethane (CH3Br).

TG–FTIR analysis of oxidation kinetics of some solid fuels under oxy-fuel conditions

A possible technology that can contribute reduction of carbon dioxide emission is oxy-fuel combustion of fossil fuels enabling to increase CO2 concentration in the exhaust gas by carrying out the combustion process with oxygen and replacing air nitrogen with recycling combustion products to obtain a capture-ready CO2 stream. The laboratory studies and pilot-scale experiments discussed during the last years have indicated that oxy-fuel combustion is a favorable option in retrofitting conventional coal firing. Estonian oil shale (OS) with its specific properties has never been studied as a fuel in oxy-fuel combustion, so, the aim of the present research was to compare thermo-oxidation of OS and some coal samples under air and oxy-fuel combustion conditions by means of thermal analysis methods. Experiments were carried out in Ar/O2 and CO2/O2 atmospheres with two oil shale and two coal samples under dynamic heating conditions. FTIR analysis was applied to characterize evolved gases and emission dynamics. Kinetic parameters of oxidation were calculated using a model-free kinetic analysis approach based on differential iso-conversional methods. Comparison of the oxidation characteristics of the samples was given in both atmospheres and it was shown that the oxidation process proceeds under oxy-fuel conditions by all studied fuels with lower activation energies, however, it can last longer as the same temperatures are compared.

Contributions to the thermal degradation mechanism under air atmosphere of PTFE by TG–FTIR analysis: Influence of the additive nature

The thermal behavior of polytetrafluoroethylene (PTFE) with glass fiber and bronze additives was studied in comparison with the synthetic PTFE under air atmosphere by applying for the first time the TG–FTIR technique. The study was performed within the 50–850°C temperature range by taking into account that this polymer is used in practice at various temperatures. The characteristic amounts from TG–DTG–DTA afforded the appreciation of the thermal stability and gave some information on the additive influence on the degradation mechanism which is entirely different from that found by us for the degradation under nitrogen atmosphere. The analysis of the gases evolved from thermal degradation brings useful information on the monomer (C2F4) obtaining in view of its recovery as well as on the influence of additives on the degradation mechanism and thus on the distribution of gaseous degradation products which was not enough studied yet. Based on the known polymerization initiator of C2F4 and on the results of the TG–FTIR analysis the most possible mechanism for the thermal degradation of synthetic and additive-containing PTFE in air atmosphere was advanced and compared with the degradation mechanism in nitrogen atmosphere.

Investigation of thermal decomposition of ascorbic acid by TG-FTIR and thermal kinetics analysis

The thermal behavior of dry solid ascorbic acid in nitrogen atmosphere in the temperature range of 25–800°C was investigated by TG-FTIR. During the thermal decomposition process, five evolved gaseous species, including H2O, CO2, CO, CH4 and HCOOH, were identified and monitored, in which HCOOH was detected for the first time. The results indicated that ascorbic acid began to decompose at 191°C. Its decomposition process consisted of three stages, and dehydration and decarboxylation to form furfural were the possible principal mechanism. The kinetic analysis for the first decomposition stage was also carried out by the isoconversional method and the master plots method. The results indicated that this process can be described by the model of 1st order reaction.

Effect of Drying Methods on the Structure and Thermal Decomposition Behavior of Ammonium Perchlorate/Graphene Composites

Graphene hydrogels were prepared by the sol-gel method,and then used to prepare ammonium perchlorate(AP)/graphene composites by the incorporation of AP.The composites were dried naturally in air,freeze-dried,or dried with supercritical CO_2.Scanning electron microscopy(SEM),elemental analyses(EA),and X-ray diffraction(XRD) were used to characterize the structure of the AP/graphene composites dried using different methods.Furthermore,the thermal decomposition behavior of the AP/graphene composites was investigated by differential scanning calorimetry(DSC) and thermogravimetric analysis/infrared spectroscopy(TG-FTIR).Drying method had an obvious influence on the morphology of the AP/graphene composites; only the AP/graphene composites dried with supercritical CO_2showed similar three-dimensional networks and porous structure to graphene aerogels.Elemental analyses revealed that the AP contents in the AP/graphene composites prepared by drying naturally,freeze-drying,and supercritical CO_2drying were 89.97%,92.41%,and 94.40%,respectively.XRD results showed that AP was dispersed homogeneously on the nanoscale in the AP/graphene composites dried with supercritical CO_2and the average particle diameter of AP was about 69 nm.DSC and TG-FTIR analyses indicated that graphene could promote the thermal decomposition of AP,particularly for the sample dried with supercritical CO_2.Independent of drying method,the low-temperature decomposition of the as-prepared AP/graphene composites was not observed and the high-temperature decomposition was accelerated.Compared to the other two drying methods,graphene in the AP/graphene composites dried with supercritical CO_2showed most obvious promoting effects.The high-temperature decomposition temperature of the AP/graphene composites dried with supercritical CO_2decreased by 83.7 °C compared with that of pure AP,and the total heat release reached 2110 J·g~(-1).Moreover,graphene also took part in the oxidation reactions with oxidizing products,which was confirmed by the generation of CO_2.

Study on the thermal behavior of casein under nitrogen and air atmosphere by means of the TG-FTIR technique

In the present paper the thermal behavior of casein is studied for the first time by the TG-FTIR technique. The casein is the main protein in milk being of a great interest due to its many uses in the cosmetic, food and pharmaceutical industries. Through the thermal stability study, the TG, DTG and DTA methods allowed the specification of the temperature range in which casein is thermally stable (0–176°C). Casein is totally degraded at 770.6°C in air without residue, and at 610°C in nitrogen atmosphere the resulted residue being 20% of the initial weight. Thermal degradation in air of casein shows two domains: an endothermic one (30–248°C) also present in nitrogen degradation, and an exothermic one (248–770.6°C). In nitrogen atmosphere all the degradation stages are endothermic. The TG-FTIR analysis shows that in 30–248°C temperature range, both in air and in nitrogen, the same gaseous species are eliminated and in the same order. In 248–770.6°C temperature range of the gaseous species evolved by the casein degradation in air is slightly different from that of the gaseous species resulted under nitrogen atmosphere. From the results of the TG-FTIR study we advanced the most probable overall mechanism of the casein thermal degradation both in air and in nitrogen atmosphere.

Silver-layered double hydroxides self-assemblies

New inorganic ensembles type layered double hydroxides enriched with silver ions were investigated in terms of thermal behavior and structural evolution by means of TG-FTIR analysis. The studies were focused on two classes of layered precursors, actually distinguished only by the nature of the divalent metal ions, in order to correlate the influence of the clay structure with the thermal behavior of the silver-anionic clay ensembles. The understanding of the thermal degradation mechanism, which is essential to advance the potential applications, requires supplementary characterization techniques such as XRD and FTIR analyses. The thermal analysis performed at three different heating rates revealed the three thermal degradation stages typical for LDHs structure, but different from sample to sample as a consequence of the different interactions between the clay layers and the interlayer anions. The interpretation of the 3D FTIR spectra of the gaseous species resulting in each stage of the thermal degradation process, by means of standard IR spectra, indicates CO2 and H2O as main evolved gasses. Moreover, the evolution curves of the gaseous species released by the thermal degradation in air of the studied anionic clays point out that the two gaseous components are eliminated into the temperature ranges corresponding to those given by TG–DTG. The comparative study of the silver-LDH ensembles from the perspective of the structural evolution during the controlled heating suggest a better response from the ensemble with structure consisting of magnesium as divalent cation in the clay network, meaning a better thermal stability.

LANTHANUM TITANATE NANOPARTICLES ER FLUIDS WITH HIGH PERFORMANCE

A new type of electrorheological (ER) fluid consisting of lanthanum titanate (LTO) nanoparticles is developed. The ER fluids were prepared by suspending LTO powder in silicone oil and the particles were fabricated by wet chemical method. This ER fluid shows excellent ER properties: The static yield stress reaches over 150 kPa under 5 kV/mm with linear dependence on the applied DC electric field, and the current density is below 10 μA/cm2. In order to investigate the affect factor on the ER behavior, the LTO powder were heated under different temperatures. The ER performances of two particles treated under different temperatures were compared and the composition changes for those particles were analyzed with TG-FTIR technique. It was found that the static yield stress of the suspensions fell from over 150 kPa to about 40 kPa and the current densities decreased prominently as the rise of the heating temperature. TG-FTIR analysis indicated that polar groups remained in the particles such as alkyl group, hydroxyl group and carbonyl group etc., contribute to the ER effect significantly. The experimental results are helpful to understand the mechanism of the high ER effect and to synthesize better ER materials.

Polynuclear complexes constructed by lanthanides and pyridine-3,5-dicarboxylate ligand: Structures, thermal and luminescent properties

Sodium salt of pyridine-3,5-dicarboxylic acid (H2pdc) reacts with the chloride (or nitrate) salt of lanthanides(III) (from La to Lu, except Pm) under hydrothermal conditions to form different kinds of coordination frameworks. The compounds of the general formula Ln2pdc3·nH2O (pdc2−=C5H3N(COO)22−, n=2.64–14) are characterized in the solid state by elemental analysis, IR spectroscopy, TG-DSC and TG-FTIR analyses, single-crystal X-ray diffraction, and X-ray powder diffraction (XRPD) techniques as well as fluorescent spectroscopy. The crystalline compounds form isostructural groups: Sm-Gd, Tb-Er and Tm-Lu. The crystal structures of [Ho2pdc3(H2O)2]·0.64H2O (1), [Er2pdc3(H2O)2]·0.68H2O (2) and [Yb4pdc6(H2O)18]·10H2O (3) compounds are reported. The compounds 1 and 2 are built up from metallic centrosymmetric dimers connected by pdc2− ligands into the 3D frameworks. There are observed 1D channels occupied by water molecules. In compound 3, the four Yb(III) centers are bridged through pdc2− ligands into the cyclic tetranuclear structure. These molecules are further assembled into a 3D supramolecular framework. This appears to be a rare example of cyclic polynuclear compounds generated by lanthanide(III) ions and polycarboxylate ligands. The luminescent properties of the complexes in visible and infrared regions upon UV excitation are discussed.

The influence of titanate nanotube on the improved thermal properties and the smoke suppression in poly(methyl methacrylate)

The well-dispersed poly(methyl methacrylate)/titanate nanotube (PMMA/TNT) composites were synthesized by in situ polymerization of methyl methacrylate (MMA) in ethanol solution. Thermal stability and the glass transition temperature of the composites are significantly enhanced with a proper amount of TNTs. The comparison between PMMA/TNTs and PMMA/TiO2 composites suggests the formation of network in PMMA/TNTs composite. The coaction of dehydration and the network is believed to be the crucial factor which improves the thermal properties. TG-FTIR analysis shows that the amount of organic volatiles of PMMA is significantly reduced and the non-flammable CO2 is generated after incorporating TNTs. It implies the reduced toxicity of the volatiles. The possible mechanism of the smoke suppression is proposed as the dehydration and adsorption effect of TNTs.

Volatilization Behavior of Fluorine in Fluoroborate Residue during Pyrolysis

Industrial hazardous waste from the fluorine chemical industry sometimes has a high content of fluorine, and incinerating it could be very poisonous if the flue gas is not properly disposed. In this study fluoroborate residue is used to represent a typical waste from the fluorine chemical industry . Thermogravimetric analysis coupled with Fourier transform infrared analysis (TG-FTIR analysis) was used to study the evolution characteristics of gaseous products during the pyrolysis of fluoroborate residue. The pyrolysis process of fluoroborate residue could be divided into three stages according to the TG analysis: moisture loss, fast decomposition, and charring. SiF(4), BF(3), and HF are found as fluorine gas species evolved in the pyrolysis process. The evolution of SiF(4) finishes at 600 °C. The evolution of BF(3) has two peaks and most of the emission happens before 600 °C. The release of HF could be divided into two stages due to the different existence of F(-). In addition, the reforming condition of different fluorine-containing gaseous substances is verified in a thermodynamic equilibrium model and the results could explain the experiment phenomenon well.

TG-FTIR Analysis of Wood Based Bio-Oil

The combustion mechanism of bio-oil derived from wood fast pyrolysis was investigated by thermogravimetric analysis coupled with Fourier transform infrared spectroscopy (TG–FTIR) in flowing air. The results show that the combustion process of bio-oil consists of two main consecutive stages at a low heating rate. The combustion reaction becomes more and more intense from the first to the second stage. The release of volatiles occurs mainly at 80～200 °C and 350～500°C, and the gaseous products in each stage are different. The main products in the first stage are H2O with a few low molecule weight compounds, such as methanol, formic acid, etc. In the second stage, some new volatiles such as CO2, CO and CH4, etc. are present. Among the above volatiles, CO2 is the dominant gaseous product in the whole combustion process. The concentrations of CO2 and CO keep increasing, and reach the maximum at about 450 °C. Over 570°C, there are few products released at the end of the combustion process.