► Pyrolysis of lignocellulosic biomass and marine biomass was studied by TGA–MS. ► The main gases produced were identified in the temperature range 200–450°C. ► CO2, H2O and light hydrocarbons were ...the main products detected. ► H2 was also observed at high temperatures due to secondary reactions. ► A multiple-step model was used to predict the pyrolysis of biomass.
The pyrolysis characteristics of three lignocellulosic biomasses (fir wood, eucalyptus and pine bark) and a marine biomass (Nannochloropsis gaditana microalgae) were investigated by thermogravimetric analysis coupled with mass spectrometry (TGA–MS). Thermal degradation of lignocellulosic biomass was divided into four zones, corresponding to the decomposition of their main components (cellulose, hemicellulose and lignin) and a first step associated to water removal. Differences in volatile matter and cellulose content of lignocellulosic species resulted in different degradation rates. Microalgae pyrolysis occurred in three stages due to the main components of them (proteins), which are greatly different from lignocellulosic biomass. Heating rate effect was also studied. The main gaseous products formed were CO2, light hydrocarbons and H2O. H2 was detected at high temperatures, being associated to secondary reactions (char self-gasification). Pyrolysis kinetics were studied using a multiple-step model. The proposed model successfully predicted the pyrolytic behaviour of these samples resulting to be statistically meaningful.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Combustion characteristics of biomass main components and three lignocellulosic biomass (fir wood, eucalyptus wood and pine bark) were investigated by thermogravimetric analysis coupled with mass ...spectrometry. The combustion of biomass was divided into two main steps, devolatilization and char oxidation stage. Heating rate effect was also studied. Generally, the higher the heating rate, the higher the decomposition temperature. Furthermore, the weight loss rate decreased due to particle temperature gradients. Combustion kinetics were studied. Models based on reaction order (Oi), nucleation (Ni) and diffusion (Di) achieved the best fitting to the experimental data. Cellulose oxidation presented the highest activation energies. CO, CO2 and H2O were the main components evolved from combustion. Additionally, light hydrocarbons (CH4 and C2H5) were also present. Finally, nitrogen compounds were in a higher proportion than sulfur compounds being released as primary amines and NOx.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Pyrolysis characteristics of three species of microalgae (SC (Scenedesmus almeriensis), NG (Nannochloropsis gaditana) and CV (Chlorella vulgaris)) have been studied by TGA–MS (thermogravimetric ...analysis coupled with mass spectrometry). The thermal behavior of microalgae samples could be described according to their biochemical composition and, in different extension, to their content in inorganic species. The high potassium content of sample SC led to the formation of a more stable char and the release of higher amount of volatiles. Pyrolysis kinetics were studied using a multiple-step model that successfully predicted the experimental behavior of these samples and was statistically validated. The gaseous products released in the pyrolysis of microalgae samples could be divided into light volatiles as H2, CO, H2O, CO2, light hydrocarbons and a condensable fraction formed by ketones, alcohols and aromatic compounds. Besides, nitrogen and sulfur compounds were generated in the form of amines, cyanides and hydrogen sulfides. Finally, an equation for predicting gas yields at a higher scale has been proposed.
•Pyrolysis process of marine biomass was studied by TGA–MS (thermogravimetric analysis coupled with mass spectrometry).•High K content of microalgae samples led to more stable chars.•The kinetic analysis of the process was performed and the process was modeled.•H2 was produced at temperatures above 400 °C due to secondary reactions.•High molecular weight compounds (ketones, alcohols and aromatic) were detected.
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•Six Colombian asphaltenes bearing high compositional variability were studied.•Compositional/structural parameters were introduced based on different techniques (FT-ICR MS, MS2, ...TGA-MS, FT-IR, 1H/13C NMR).•DBE26/DBE15 ratio by tandem mass spectrometry provided the archipelago/island structural prevalence in asphaltenes samples.•The predominancy of peri-condensed and cata-condensed structures as an additional asphaltenes’ structural characteristic were disclosed.
The advanced characterization of asphaltenes has been extensive and fruitful during the last two decades but with many gaps. Despite the efforts to reveal the molecular architectures that dominate asphaltenes, some pieces of the puzzle are still missing. Critical information that can lead to a global picture of asphaltenes remains scarce. The last in-depth discussions have been around the island/archipelago architectures found in the asphaltenes from the Wyoming deposit and Athabasca bitumen, respectively. With the premise of stablishing an island and archipelago motif domain, along this contribution we extend the discussion throughout six diverse Colombian asphaltenes from different origins. We set a parameterization based on outer island/archipelago structures and experimental data obtained from different characterization techniques such as elemental analysis, 1H NMR, 13C NMR, IR spectroscopy, FT-ICR-MS, tandem MS, and TGA for thermal combustion and pyrolytic/coke formation. In each case, compositional parameters were proposed to classify asphaltenes as islands o archipelago dominant, with cata- or peri-condensed aromatic systems. Particularly, by using tandem mass spectrometry data, a new parameter named island factor FIsland was proposed to establish the island/archipelago prevalence of asphaltenes. The advantage of this broad analysis leads us to conclude that there is not only a marked difference between archipelagos and islands but also the type of conjugated system cata- or peri-condensed, which makes visible the relevance of having a broad concept of the asphaltene molecular architecture and their impact on large-scale properties. This report consists of a comprehensive discussion using experimental techniques applied on diverse asphaltenes not reported in the literature before.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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•Hydrogenation kinetics of limestone under fluidized condition was firstly explored.•MFB-TGA-MS was employed to measure both mass and gas signals simultaneously.•Self-catalytic ...activity of calcined CaO with 79% CO2 conversion in ICCU-RWGS.•Apparent model of limestone hydrogenation was developed to analyze the kinetics.
The integrated CO2 capture and utilization (ICCU) in conjunction with the reverse water–gas shift (RWGS) reaction has emerged as a promising approach to achieve carbon neutrality. However, the scalability of CaCO3 hydrogenation in the context of large volumes of industrial flue gas is impeded by the limited understanding of its performance under fluidized and iso-thermal conditions. This study utilized micro-fluidized bed thermogravimetric analysis coupled with mass spectrometry (MFB-TGA-MS) and in-situ measurements to investigate limestone decomposition under H2 and Ar atmospheres. Results showed that H2 atmosphere increased the limestone decomposition rate by 5-fold (79.1% CO2 conversion and ∼100% CO selectivity at 710 °C) compared to Ar, with RWGS as the dominant route and self-catalytic activity of calcined CaO. Morphology evolution revealed finer pores and textures under H2 conditions. Meanwhile, apparent kinetic models analyzed experimental data and showed a reduction in activation energy from 178.5 kJ/mol (Ar) to 161.3 kJ/mol (H2). These findings support the effectiveness of ICCU-RWGS approaches for further commercialization.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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•Pyrolysis and combustion processes of three manure samples were studied by TGA–MS.•The economic viability, energetic and environmental impacts were evaluated by LCA.•The main ...components of the gas produced were: H2, CH4, CO, C2 hydrocarbons and CO2.
The valorization of three different manure samples via pyrolysis and combustion processes was evaluated. Dairy manure (sample Pre) was biologically pretreated by anaerobic digestion (sample Dig R) whereas swine manure (sample SW) was pretreated by a biodrying process. Thermal behavior of manure samples were studied by means of thermogravimetric analysis coupled with mass spectrometry (TGA–MS). These processes could be divided into four general stages: dehydration, devolatilization, char transformation (oxidation for combustion) and inorganic matter decomposition. The main differences observed among the samples were attributed to their different composition and pretreatment. The economic feasibility, energetic and environmental impacts of pyrolysis and combustion technologies for dairy samples were carried out by means of life cycle assessment (LCA) methodology. Four different scenarios were analyzed. The economic feasibility of the pyrolysis process was demonstrated, being sample Dig R the best environmental option. However, the combustion of sample Pre was the best energetic option.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
•Evaluation based on interlaboratory test material (suspended matter w/ and w/o microplastic).•TED-GC/MS is most powerful to determine microplastic in environmental samples.•TGA-FTIR showed high ...robustness in general and good results.•TGA-MS provides PVC determination that is not possible with TED-GC/MS.•MCC is introduced as promising screening tool with 10–20 min measurement time.
Microplastic particles are currently detected in almost all environmental compartments. The results of detection vary widely, as a multitude of very different methods are used with very different requirements for analytical validity.
In this work four thermoanalytical methods are compared and their advantages and limitations are discussed. One of them is thermal extraction-desorption gas chromatography mass spectrometry (TED-GC/MS), an analysis method for microplastic detection that has become established in recent years. In addition, thermogravimetric analysis coupled with Fourier-transform infrared spectroscopy (TGA-FTIR) and mass spectrometry (TGA-MS) were applied, two methods that are less common in this field but are still used in other research areas. Finally, microscale combustion calorimeter (MCC) was applied, a method not yet used for microplastic detection.
The presented results are taken from a recently published interlaboratory comparison test by Becker et al. (2020). Here a reference material consisting of suspended matter and specified added polymer masses was examined, and only the results of the recoveries were presented. In the present paper, however, the results for the individual polymers are discussed in detail and individual perspectives for all instruments are shown.
It was found that TED-GC/MS is the most suitable method for samples with unknown matrix and unknown, variable kinds and contents of microplastic. TGA-FTIR is a robust method for samples with known matrix and with defined kinds of microplastic. TGA-MS may offer a solution for the detection of PVC particles in the future. MCC can be used as a very fast and simple screening method for the identification of a potential microplastic load of standard polymers in unknown samples.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Identification of PT30 resin degradation products by TGA-IR and TGA-MS.•Proposal of a degradation mechanism for PT30 resin in a nitrogen atmosphere.•Identification of the initiation degradation ...reaction based on the results of Density Functional Theory (DFT) calculations which highlight the less energetic network bonds.•Description of each step in the chain scissions of the PT30 resin.•Description of each step in the creation of degradation products.
The non-isothermal thermal degradation of the cured phenolic triazine thermoset resin (PT30) was considered under nitrogen atmosphere. Thermogravimetric analyses (TGA) showed that the degradation mechanism was decomposed in three main steps occurring at 440°C, 550°C, and 720°C. To understand the chemical reactions that happen, TGA experiments were coupled with the analyses of the gaseous products by Fourier transform infrared detection (TGA/FTIR) and by mass spectrometry (TGA/MS). A degradation mechanism is proposed based on these experimental results and on Density Functional Theory (DFT) calculations. It was found that carbon dioxide is the main degradation product generated by the oxygen-carbon chain scissions. In the second step, triazine rings’ rupture led to the formation of cyanide hydrogen and probably cyanic/isocyanic acid. Then, various aromatic compounds are produced from chain scissions and molecules’ recombination. Analyses of these degradation products contributed to proposing assumptions of thermal degradation mechanisms of the PT30 resin.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Alternative to common TGA–FTIR/MS techniques for analysing complex mixtures of thermal decomposition products of polymers.•Development of a new technique consisting of thermogravimetry ...(TGA)–solid-phase extraction (SPE)–thermal desorption (TDS)–gas chromatography mass spectrometry (GC–MS).•Ease of handling, unambiguous product identification, good repeatability.•Influence by specific binding of different products.
For analysis of the gaseous thermal decomposition products of polymers, the common techniques are thermogravimetry, combined with Fourier transformed infrared spectroscopy (TGA–FTIR) and mass spectrometry (TGA–MS). These methods offer a simple approach to the decomposition mechanism, especially for small decomposition molecules. Complex spectra of gaseous mixtures are very often hard to identify because of overlapping signals. In this paper a new method is described to adsorb the decomposition products during controlled conditions in TGA on solid-phase extraction (SPE) material: twisters. Subsequently the twisters were analysed with thermal desorption gas chromatography mass spectrometry (TDS–GC–MS), which allows the decomposition products to be separated and identified using an MS library. The thermoplastics polyamide 66 (PA 66) and polybutylene terephthalate (PBT) were used as example polymers. The influence of the sample mass and of the purge gas flow during the decomposition process was investigated in TGA. The advantages and limitations of the method were presented in comparison to the common analysis techniques, TGA–FTIR and TGA–MS.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
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