Thermogravimetry Coupled With Fourier Transform Infrared Spectroscopy Research Articles

Assessment of heating rate and mixing ratio on the synergistic effects of co-pyrolysis of pine sawdust and high-density polyethylene

The co-pyrolysis of biomass and plastics presents a promising approach for generating hydrocarbon fuels and high-value chemicals while addressing environmental pollution concerns. This study investigates the pyrolysis process by examining mixtures of pine sawdust (PS) and high-density polyethylene (HDPE) with varying mass proportions and heating rates using analytical methods including thermogravimetric analysis and differential scanning calorimetry (TGA-DSC), thermogravimetry coupled with Fourier transform infrared spectroscopy (TG-FTIR) coupled analysis, pyrolysis gas chromatography-mass spectrometry (Py-GC-MS) and kinetic analysis. The study highlights the impact of heating rate on product distribution, with significant changes observed when the biomass ratio is at 30 %. Moreover, the addition of high-density polyethylene leads to an increase in polyol content in the liquid product. Analysis of product types reveals that plastics act as “hydrogen donors,” supplying hydrogen to biomass during co-pyrolysis, thus reducing oxygen chemicals. Results from the kinetic analysis show that the activation energy for co-pyrolysis is lower than individual pyrolysis, also indicating a synergistic effect. Overall, this research provides insights into the synergistic benefits of co-pyrolysis and establishes a theoretical foundation for advancing co-pyrolysis technology.

Thermal stability and flammability of several quaternary ammonium ionic liquids

With the development of potential large-scale industrial application of quaternary ammonium ionic liquids in the fields of gas separation, high-temperature lubricants and even rocket propellants, deep investigations are required to reveal the possible hazards of thermal decomposition, the flammability and the hazardous gaseous products. In this study, the thermal stability of five typical quaternary ammonium ionic liquids, [N2222][NTF2], [N2222][PF6], [N2222]Br, [N4444]Br and [N4444][PF6], were studied using thermogravimetric analyser (TGA). The results show that the thermal stability of ionic liquids follows an order of [N2222][NTF2] > [N2222][PF6] > [N4444][PF6] > [N2222]Br > [N4444]Br, indicating that the thermal stability is obviously affected by the anion, with an order of [NTF2]− > [PF6]− > Br−. Besides, increasing the alkyl chain length in the cation will reduce the thermal stability. In addition, Fire Testing Technology (FTT) cone calorimeter was used to investigate the flammability and found that the longer alkyl chains of quaternary ammonium ionic liquids make great contribution on larger the total heat release, the peak value of heat releasing rate and shorter ignition time. Moreover, with the same cation, [N2222]Br and [N4444]Br were shortened the ignition time and produced larger amount of heat than [N2222][PF6] and [N4444][PF6], respectively. It clearly shows that the risk of fire is also affected by the anion, with an order of Br− > [PF6]− > [NTF2]−. Finally, the decomposition products were measured by thermogravimetry coupled with Fourier-transform infrared spectroscopy (TG-FTIR), and it is deduced that the nucleophilic Br− from [Nmmmm]Br (m = 2,4) and F− from the [NTF2]− and [PF6]− during decomposition will attack the alkyl chain of the cation, which generated gaseous products such as fluoroalkanes, bromoalkanes, olefins, etc.

TG-DSC and TG-FTIR Studies of Annelated Triazinylacetic Acid Ethyl Esters-Potential Anticancer Agents.

To avoid problems associated with the storage and processing of newly developed potential medicines, there is a need to carry out thermal studies in the preclinical phase of drug development. The thermal behaviour and decomposition pathway of a whole novel class of patented potential molecular pharmaceutics, i.e., ethyl 2-[4-oxo-8-(R-phenyl)-4,6,7,8-tetrahydroimidazo[2,1-c][1,2,4]triazin-3-yl]acetates (1-6) were reported for the first time in inert and oxidative atmospheres. The experiments were conducted with the use of simultaneous thermogravimetry/differential scanning calorimetry (TG-DSC) and simultaneous thermogravimetry coupled with Fourier transform infrared spectroscopy (TG-FTIR). The decomposition pathways of compounds 1-6 were found to be different under oxidative and inert conditions. It was proven that the investigated molecules reveal higher thermal stability under a synthetic air atmosphere than under a nitrogen atmosphere, and their decomposition is preceded by the melting process. Among all the investigated compounds, only the meta-chloro derivative (4) was found to exhibit interesting polymorphic behaviour at a low heating rate (10 °C min-1). It was proven that the oxidative decomposition process of the studied molecules proceeds in three overlapping stages accompanied by strong exothermic effects. Additionally, it was concluded that the title compounds were stable up to a temperature of 195-216 °C in an atmosphere of synthetic air, and their thermal stability decreased in the order of R at the benzene ring: 4-CH3 > 3,4-Cl2 > 4-Cl > H > 2-OCH3 > 3-Cl.

Effects of illite–smectite clay minerals on the thermal evolution of aliphatic organic matter-clay complexes: a study with thermogravimetry coupled with Fourier transform infrared spectroscopy (TG-FTIR)

Effects of illite–smectite clay minerals on the thermal evolution of aliphatic organic matter-clay complexes: a study with thermogravimetry coupled with Fourier transform infrared spectroscopy (TG-FTIR)

Experimental investigation and numerical modeling of oxidative pyrolysis mechanism of mining PVC cable sheath

Cables modified with flame retardants are widely used in the coal mining process to enhance their fire safety performance. This paper investigates experimentally and numerically the thermo-oxidative degradation process of PVC-based mining cable sheath, which consists of PVC resin and plasticizers (Phthalate esters), fillers (Calcium carbonate), and flame retardant (Antimony trioxide) as additives. Thermogravimetry coupled with Fourier transform infrared spectroscopy (TG-FTIR) experiments were performed at different heating rates in an air atmosphere. TG results showed that the decomposition processes of mining PVC cable sheath are more complicated than those of pure PVC with additional degradation steps, which was further confirmed by FTIR gas analysis. A deconvolution method was used to distinguish the independent reactions from the overlapped derivative thermogravimetric (DTG) peaks. It was found that the whole degradation process can be divided into seven steps, based on which an oxidative pyrolysis model was developed: pyrolysis of plasticizers (steps 1 and 2), dehydrogenation (step 3), emission and combustion of volatile fraction (step 4), carbon combustion (step 5), oxidative pyrolysis of complicated additives (step 6), and decomposition of residues (step 7). The kinetic triplets (activation energy, pre-exponential factor, and reaction model function) for each reaction were firstly calculated using three commonly used model-free methods and then further optimized using the genetic algorithm (GA). Based on the optimized parameters, the reaction mechanisms and their associated kinetic parameters were determined. The findings of this study are important in understanding the oxidative pyrolysis process of PVC cable sheath, and the obtained kinetic parameters can also be used for its pyrolysis and fire modeling, waste recycling, and risk assessment.

Synthesis and pyrolysis mechanism of phenolphthalein poly(aryl ether sulfone) containing isopropyl groups

A novel phenolphthalein poly(aryl ether sulfone) polymer containing isopropyl groups (iPrPESC) has been successfully synthesized by SN2 aromatic nucleophilic polycondensation reaction. The pyrolysis mechanism and behavior of iPrPESC were investigated by thermogravimetry coupled with Fourier transform infrared spectroscopy (TG-FTIR) and pyrolysis combined with gas chromatography/mass spectrometry (Py-GC/MS). TG-FTIR and Py-GC/MS were used to identify the thermal decomposition products and to determine the possible thermal degradation mechanism. The main mechanism for iPrPESC was one-stage pyrolysis involving main-chain random scission, and the major products of SO2 and phenol were released from the sulfone and ether groups in iPrPESC. The thermal degradation activation energy of iPrPESC was calculated to be 151 ± 4 and 139 ± 4 kJ mol−1 by the Flynn–Wall–Ozawa and Kissinger methods, respectively, which were much lower than that of phenolphthalein poly(aryl ether sulfone). Furthermore, introduction of isopropyl groups on the main chain can significantly reduce the char yield.

The effect of oxygen on the thermal stability and decomposition behaviours of 1,3-dimethylimidazolium nitrate for application using STA, ARC and FTIR

The thermal decomposition and runaway reaction of 1,3-dimethylimidazolium nitrate ([Mmim]NO3), a typical nitrate IL, were studied by a simultaneous thermogravimetric analyzer (STA) and accelerating rate calorimeter (ARC). The STA results show that the thermal decomposition of [Mmim]NO3 is divided into two stages, and the decomposition behaviour is similar in nitrogen or oxygen. The experimental results under adiabatic conditions indicate that [Mmim]NO3 has higher Tmax and Pmax than other imidazolium ILs, which reflects the greater explosion hazard of [Mmim]NO3. The apparent activation energies of [Mmim]NO3 were 86 kJ/mol and 83 kJ/mol, as calculated by the F-W-O and K-A-S methods. The complete thermal decomposition gas products of [Mmim]NO3 were analyzed by thermogravimetry coupled with Fourier transform infrared spectroscopy (TG-FTIR), and the gas released by thermal decomposition of [Mmim]NO3 does not react with oxygen. Therefore, the decomposition reaction of [Mmim]NO3 was not positively related to the concentration of oxygen, which indicated that [Mmim]NO3 could play an active role in the reactions in the presence of oxygen. The results of this study may provide theoretical and experimental basis for [Mmim]NO3 safety precautions in storage and transportation.

Investigation on the co-pyrolysis of agricultural waste and high-density polyethylene using TG-FTIR and artificial neural network modelling

To realize utilization of agricultural and plastic waste to alleviate environmental pollution, the individual pyrolysis and co-pyrolysis characteristics of kidney beans stalk (KS) and high-density polyethylene (HDPE) were investigated. Thermogravimetry coupled with Fourier transform infrared spectroscopy (TG-FTIR) was used to investigate the pyrolysis behaviour, synergistic effect, kinetics and gaseous product evolution of different samples. In addition, an artificial neural network (ANN) model was established to predict the mass change with temperature during sample pyrolysis or co-pyrolysis. The results showed that the decomposition of HDPE was easier than that of KS, and synergistic and inhibitive effects occurred during co-pyrolysis. The synergistic or inhibitive effect was most significant from 470 to 510 ℃. The FTIR analysis results showed that gaseous products of KS pyrolysis were mainly oxygen-containing compounds including CO2, CO, ketones, aldehydes, esters, etc., while those of HDPE pyrolysis were mainly hydrocarbons including alkanes, alkenes, aromatic rings, etc. The co-pyrolysis of samples with different proportions promoted or inhibited the production of some gaseous products to different degrees. Moreover, the activation energy of the two stages during co-pyrolysis was lower than that of the pure sample. The established ANN model can effectively predict the mass loss of a sample with temperature.

Thermal stability and exothermic behaviour of imidazole ionic liquids with different anion types under oxidising and inert atmospheres

Ionic liquids (ILs), as a type of salt that is liquid at room temperature, break the entrenched views on salt when it was proved that some of them could be ignited. In this research, an innovative method was used to evaluate the thermal stability of such special salts and speculated their ignition mechanism based upon gas analysis. Four typical representative imidazole ILs (BMIMBF4, BMIMDCN, BMIMNO3, and BMIMOAc) were selected, and their thermal decomposition characteristics and thermal effect were obtained by simultaneous thermogravimetric analyser (STA) and differential scanning calorimetry (DSC), respectively. Furthermore, their decomposition products were investigated by thermogravimetry coupled with Fourier-transform infrared spectroscopy (TG-FTIR). It is noteworthy that they behaved diversely in DSC experiments and exhibited a radically different thermal effect in their decomposition. In addition, there exists positive feedback in the mechanism of the exothermic phenomenon of selected ILs in the air. Nevertheless, TG curves of four selected ILs were almost the same under air or nitrogen conditions. Series TG-FTIR experiments confirmed that the initial decomposition products of BMIMBF4 and BMIMDCN under air or nitrogen are extremely different. The decomposition products of BMIMNO3 and BMIMOAc in the air atmosphere have more oxidative products than nitrogen. The results denoted that the thermal decomposition mechanism of the four selected ILs in the air were the same as under nitrogen. The reducibility of the decomposition products induced the peculiar thermal effects of these imidazole ILs under the different gas environments. This study was innovative in researching the thermal effect and mechanism of imidazole ILs’ decomposition and provided certain safety guidance for the process safety and loss prevention of imidazole ILs.

Catalytic pyrolysis kinetic behaviour and TG-FTIR-GC–MS analysis of waste fishing nets over ZSM-5 zeolite catalyst for caprolactam recovery

Caprolactam is the main compound of nylon 6 waste fishing nets (WFNs) and its recovery conserves natural resources, maximizes WFNs economic performance, and closes the circular economy loop of the fishing net industry. Within the framework and as a part of the Healthy Seas’ initiative to clean the oceans from waste fishing nets (WFNs), and to valorise it, this research aims to study the catalytic pyrolysis behaviour of the WFNs extracted from oceans in order to study their potential applications in the energy conversion field. The catalytic pyrolysis experiments of WFNs over ZSM-5 Zeolite catalyst (2.5, 5, 10, 20, 50 wt%) were conducted using thermogravimetry (TG) coupled with Fourier-transform infrared spectroscopy (TG-FTIR) and gas chromatography–mass spectrometry (GC-MS) at different heating rates (5–30 °C/min). Also, the kinetics of ZSM-5/WFNs catalytic pyrolysis was studied by model-free methods (KAS, FWO, and Friedman). In addition, the distributed activation energy model (DAEM) and the independent parallel reaction kinetic model (IPR) combined with the optimization algorithm were used to fit the TGA-DTG experimental data and to calculate the parameters that can achieve the minimum deviation. The TGA results showed that the main decomposition zone was located in the range 342–476 °C with a total weight loss 83-75 wt% (based on the amount of catalyst). Meanwhile, FTIR and GC-MS results manifested that alkyl C–H stretch functional group, carbonyl functional group (CO), and caprolactam (83.15%; at 20 wt% of ZSM-5) are the main groups and volatile compounds in the decomposed WFNs samples. The model-free kinetics analysis showed that all activation energies were estimated at 112 kJ/mol (WFNs) and 158, 230, 197, 201, and 220 kJ/mol for ZSM-5/WFNs samples (2.5, 5, 10, 20, 50 wt%). At the same time, DAEM and IPR models proved a high prediction to fit TG curves at all heating rates. Based on these results, catalytic pyrolysis using 20 wt% of ZSM-5 can be used as a promising technology for extracting caprolactam from WFNs with high yield (83%). The recovered caprolactam can be used in the production of nylon fibres, nylon thin films, carpets, textiles, resins, etc.

Highly effective flame retardant lignin/polyacrylonitrile composite prepared via solution blending and phosphorylation

Aiming at improving the thermal stability and flame retardancy of polyacrylonitrile (PAN), a novel flame retardant PAN composite was prepared via a facile approach. First, lignin (LIG) and PAN were dissolved in dimethyl sulfoxide (DMSO) to form a uniform blend solution of LIG and PAN, then the solution was poured into the mould to scrape the LIG/PAN composite film. Subsequently, the flame retardant LIG/PAN composite (FR-LIG/PAN) was fabricated via phosphorylation. The structure of pure PAN, LIG, LIG/PAN and FR-LIG/PAN composite was characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The thermal and combustion properties of the samples were evaluated by using thermogravimetric analysis (TGA) and cone calorimeter test (CCT). In addition, the cross section and char residue of FR-LIG/PAN composite after combustion were observed by scanning electron microscopy (SEM). Furthermore, the elemental compositions and contents of the cross section and char residue of FR-LIG/PAN composite after combustion were tested by energy-dispersive X-ray spectroscopy (EDS). The results indicated that hydroxyl group and benzene skeleton were present in LIG/PAN and the phosphorus element was successfully introduced into FR-LIG/PAN composite via phosphorylation. The amount of char residue for FR-LIG/PAN at 800 °C is more than those of pure PAN and LIG/PAN. SEM photos indicate the expansion characteristics of the char residue, and EDS results prove that the uniform distribution of elements in the cross-section of FR-LIG/PAN composite. Moreover, FR-LIG/PAN exhibits the lowest peak heat release rate (pHRR) and smoke production rate (SPR). These results demonstrated that FR-LIG/PAN had excellent flame retardancy and char forming ability. In addition, the composition of the gases evolved from pyrolysis process of FR-LIG/PAN was analyzed by thermogravimetry coupled with Fourier transform infrared spectroscopy (TG-FTIR). The main pyrolysis products in gas phase are H2O, CO2 and PO•. This work proposes one facile method for preparation of practical flame retardant PAN composite.

Thermal stability and flammability assessment of 1-ethyl-2, 3-dimethylimidazolium nitrate

1-Ethyl-2, 3-dimethylimidazolium nitrate [C2mmim][NO3] is a typical solvent for industrial applications. Under inappropriate temperatures, [C2mmim][NO3] may present a flammability hazard due to thermal decomposition. This study investigated the thermal stability and flammability of [C2mmim][NO3] via simultaneous thermogravimetric analyzer, homemade combustion test device (CTD) with high speed camera, and thermogravimetry coupled with Fourier transform infrared spectroscopy (TG-FTIR). The thermal decomposition of [C2mmim][NO3] was divided into two parts based upon the dynamic experiments, and the maximum operating temperature was determined to comprehensively estimate the thermal stability of [C2mmim][NO3]. CTD experiments indicated that [C2mmim][NO3] could produce intense combustion when heated. Further TG-FTIR experiments confirmed that [C2mmim][NO3] decomposed to produce a large number of flammable gases, such as ethylene, which might be the reason that [C2mmim][NO3] has prominent flammability.

Comparison of oxidation behavior of linear and branched alkanes

In this research, the oxidation behavior of six linear and branched alkanes was investigated using high-pressure differential scanning calorimeter (HP-DSC) and thermogravimetry coupled with Fourier-transform infrared spectroscopy (TG-FTIR) to compare the similarities and differences between branched and linear alkanes. The results indicated that both branched and linear alkanes showed only low-temperature oxidation (LTO), which implies that alkanes barely contribute in coke formation and thus no obvious high-temperature oxidation (HTO) was observed as no enough fuel was deposited. The LTO of linear alkanes seems to be independent of their carbon number, which, however, does not apply to branched alkanes. The oxidation behavior of branched alkanes was different from their linear chain counterparts due to the effect of their different molecule structure. Branched alkanes reacted earlier and faster at initial stage relative to their linear chain counterparts, but their reaction rates became slower at later stage with the increase of temperature. Branched alkanes can produce some oxidized compounds with CO group, while linear alkanes can form more carbonyl groups and some oxidized compounds (like carboxylic acids) that can help to produce more CO2 by decomposition.

Formation of macromolecules with peptide bonds via the thermal evolution of amino acids in the presence of montmorillonite: Insight into prebiotic geochemistry on the early Earth

The formation of macromolecules is an indispensable step in the process leading to the appearance of life on Earth. As their constituents were widely distributed over geological time and space on the surface of the primitive Earth, clay minerals are regarded as an essential factor influencing the formation of macromolecules due to their high reactivity and their close association with organic matter that could be the precursors of macromolecules. Over the years, many researchers have studied the roles of clay minerals in macromolecules formation through the condensation of amino acids (AAs) in aqueous systems in order to understand the thermal evolution of organic matter (OM) in pristine oceans. However, the condensation of AAs in non-aqueous systems has received limited attention. In particular, the stability and evolution of AAs in volcanic eruption environments that are rich in clay minerals have rarely been investigated. In this work, the influence of clay mineral on the thermal evolution of AAs was studied. Two types of clay-AA complexes, i.e., clay-AA interlayer complexes and clay-AA external complexes (where AAs exist outside the interlayer structure) were used. An expandable clay mineral, montmorillonite (Mt), was chosen as the typical clay mineral, and L-arginine (Arg) and glycine (Gly) were used as the model AAs for the preparation of clay-AA complexes. In situ diffuse-reflectance infrared Fourier transform spectroscopy (in situ DRIFT) was used to monitor the thermal evolution behaviors of the clay-AA complexes, such as the formation of macromolecules with peptide bonds, and thermogravimetry (TG) and TG coupled with Fourier transform infrared spectroscopy (TG-FTIR) analyses were used to investigate the decomposition of the produced macromolecules. The results show that Mt strongly affects macromolecules formation during the thermal evolution of AAs, which is mainly due to that the inherent solid acidity of the different structural sites of Mt varies. When AAs are present on the external surfaces of Mt, the interaction between AAs and clay minerals substantially decreases the initial formation temperature of the macromolecules with peptide bonds (for Arg) and strongly affects the types of condensation products (for Gly). When AAs exist in the interlayer structure of Mt, the interlayer structure has a steric effect on the thermal evolution of these monomers, which, together with the effects of the molecular structure of Arg, enhances the initial temperature of condensation and increases the thermal decomposition temperature of the formed macromolecules. Regardless of whether AAs exist in the interlayer sites or on the external surfaces of clay minerals, clay-OM association is able to protect macromolecules, postponing their thermal decomposition. The present work indicates that macromolecules with peptide bonds could readily form via the condensation of AAs under dry high-temperature conditions, which implies that non-aqueous thermal conditions resulting from volcanic activities might be a favorable geological setting for prebiotic chemical evolution on the early Earth.

Structural and Thermoanalytical Characterization of 3D Porous PDMS Foam Materials: The Effect of Impurities Derived from a Sugar Templating Process.

Polydimethylsiloxane (PDMS) polymers are extensively used in a wide range of research and industrial fields, due to their highly versatile chemical, physical, and biological properties. Besides the different two-dimensional PDMS formulations available, three-dimensional PDMS foams have attracted increased attention. However, as-prepared PDMS foams contain residual unreacted low molecular weight species that need to be removed in order to obtain a standard and chemically stable material for use as a scaffold for different decorating agents. We propose a cleaning procedure for PDMS foams obtained using a sugar templating process, based on the use of two different solvents (hexane and ethanol) as cleaning agents. Thermogravimetry coupled with Fourier Transform Infrared Spectroscopy (TG-FTIR) for the analysis of the evolved gasses was used to characterize the thermal stability and decomposition pathway of the PDMS foams, before and after the cleaning procedure. The results were compared with those obtained on non-porous PDMS bulk as a reference. Micro-CT microtomography and scanning electron microscopy (SEM) analyses were employed to study the morphology of the PDMS foam. The thermogravimetric analysis (TGA) revealed a different thermal behaviour and crosslinking pathway between bulk PDMS and porous PDMS foam, which was also influenced by the washing process. This information was not apparent from spectroscopic or morphological studies and it would be very useful for planning the use of such complex and very reactive systems.

The thermal decomposition mechanism of irbesartan

Irbesartan (IBS) is an inhibitor of angiotensin II receptor. In order to study the thermal stability and the thermal decomposition mechanism of IBS, the thermal decomposition processes of IBS in nitrogen and in air atmospheres were studied by means of thermogravimetry (TG) and differential scanning calorimetry (DSC), the evolved gaseous products from thermal decomposition were identified with thermogravimetry coupled with Fourier transform infrared spectroscopy (TG-FTIR), and the residues of thermal decomposition at various temperatures were analyzed with infrared spectra, high-performance liquid chromatography (HPLC) and liquid chromatography-mass spectrometry (LC–MS). The molecular bond orders were calculated by GAMESS program of quantum chemistry, and the thermal decomposition mechanism of IBS was discussed. The results indicated that the thermal decomposition of IBS is a three-stage process and the initial temperatures of the decomposition are 204.7 and 201.0 °C in nitrogen and in air, respectively. The initial step of the decomposition is the partial decomposition of imidazolone and tetrazol sections. The thermal stability of IBS is quite good in the routine temperature.

Introducing Students to Thermogravimetry Coupled with Fourier Transform Infrared Spectroscopy

Thermogravimetry coupled with Fourier transform infrared spectroscopy (TG-FTIR) is a useful technique for the thermal and structural characterization of materials at academic and research levels. This paper describes an experiment for chemistry students to understand the use of TG-FTIR for advanced qualitative and quantitative thermal analysis using a natural compound as a sample. In the classroom, students learned about the fundamental principle of thermal analysis, TG-FTIR instrumentation, and different applications of this coupled technique for materials characterization. In the laboratory, students received a description of each part of the TG-FTIR system, as well as how to tune the system and to develop a method. The primary objective of the experiment was to guide them in the interpretation of results including thermograms, infrared spectra, DSC, and Gram Schmidt (GS) curves. For this, students prepared and analyzed cellulose fibers extracted from pineapple leaves and a mixture of them with sodium h...

Study of breakage of main covalent bonds during co-pyrolysis of oil shale and alkaline lignin by TG-FTIR integrated analysis

Pyrolytic vapor generated over different temperature ranges can be correlated with breaking of different groups of covalent bonds. In the present study, pyrolysis of oil shale and alkaline lignin was studied by thermogravimetry coupled with fourier transform infrared spectroscopy (TG-FTIR) analysis. As the dominant fraction of pyrolytic gaseous products, methane (CH4) was selected as an entry point to track the breakage of main covalent bonds during pyrolysis of oil shale and alkaline lignin. Through applying the deconvolution method, overall CH4 evolution and differential thermogravimetric (DTG) curves of pyrolysis of oil shale and alkaline lignin could be fitted by a series of sub-curves assigned to different groups of covalent bonds. This indicated that the mass loss of oil shale was mainly caused by the fracture of three groups of covalent bonds. In contrast, mass loss of alkaline lignin was mainly caused by the fracture of two groups of covalent bonds. Furthermore, detailed influence of co-pyrolysis on the cleavage of covalent bonds was also analyzed for different blending ratios of oil shale and alkaline lignin. The results revealed that co-pyrolysis of alkaline lignin and oil shale led to the enhancement in CH4 yield by promoting the breakage of linkages. It was also found that among three groups of covalent bonds, the third was most significantly influenced due to reduction in its bond energy.

Pyrolysis behaviors of organic matter (OM) with the same alkyl main chain but different functional groups in the presence of clay minerals

Abstract Organic matter (OM)-clay mineral complexes, especially OM-clay interlayer complexes, exist widely in soil, sediment, and source rock. These associations can influence the pyrolytic behaviors of OM. In addition, the nature of OM may also affect pyrolysis due to the variety and complexity of the structure and chemical composition of natural organics. In this study, to investigate the influences of the nature of OM as well as the interface association between OM and clay minerals on the pyrolysis of OM, interlayer clay-OM complexes and clay-OM mixtures were prepared and thermogravimetry coupled with Fourier transform infrared spectroscopy (TG-FTIR) was adapted to monitor the pyrolytic temperatures and products of these complexes. A series of OM with the same alkyl main chain but different functional groups, i.e., Lauric acid (LA), Dodecylamine (DA), 12-Aminolauric acid (ALA) and Dodecyl trimethyl ammonium bromide (DTAB), was used, and montmorillonite (Mt) was selected as the representative clay mineral. The results showed that Mt decreased the decomposition temperature of the carboxyl groups that contained OM (LA and ALA), promoted the generation of CO2 via the catalysis of the Lewis acid sites of Mt, and delayed the decomposition of DA and DTAB. The interlayer Bronsted acid sites allowed the nitrogen-containing organics to undergo Hoffmann elimination. The pyrolytic behaviors of OM within the interlayers of Mt were more strongly affected than those on the external surface of Mt The pyrolytic performance of OM was closely related to the association ways between OM and clay minerals, the nature of clay minerals, and the nature of OM. The interlayer space was shown to be particularly important for the preservation and catalysis of organics.

Gas–condensed phase flame-retardant mechanisms of tris(3-nitrophenyl) phosphine/triphenyl phosphate/ABS

Tris(3-nitrophenyl) phosphine (NPPh3), a flame retardant containing phosphorus and nitro group, is synthesized. And a novel flame retardant loading with NPPh3 and triphenyl phosphate (TPP) is prepared to flame-retardant acrylonitrile–butadiene–styrene (ABS). The effects of NPPh3 and TPP on the flammability of ABS are studied by various methods. The flame retardation of ABS/NPPh3/TPP composite is characterized by limiting oxygen index method and vertical and horizontal burning tests (UL-94). Compared with the systems with ABS/NPPh3 and ABS/TPP alone, ABS/NPPh3/TPP obtains a higher limiting oxygen index. Additionally, the flame-retardant effect of ABS/NPPh3/TPP in condensed phase is studied by thermogravimetric analysis (TG), scanning electron microscopy, and Fourier transform infrared spectroscopy (FTIR). The gases evolved during thermal degradation process in nitrogen are studied by means of thermogravimetry coupled with Fourier transform infrared spectroscopy (TG-FTIR). The results show that ABS/NPPh3/TPP exerts gas-condensed phase flame-retardant effect.