Thermal Decomposition Of Cellulose Research Articles

Study on the effect of different solvent pretreatment on the pyrolysis characteristics of tobacco

Solvent pretreatment can remove some components in biomass and change the distribution of its pyrolytic products. Combined with the physicochemical analysis of tobacco before and after solvent pretreatment, the pyrolysis characteristics of tobacco and the changes of pyrolysis oil components after the removal of some components of tobacco by deionized water, 75% ethanol, and 3% lactic acid were evaluated by thermogravimetry (TG) and high-temperature pyrolysis experiments. The results showed that the O/C atomic ratio of tobacco decreased after solvent pretreatment, and the high concentration of ethanol had a huge effect on the intensity of the peaks associated with aromatic and pyranic rings. TG analysis showed that the pyrolysis of pretreated tobacco was mainly characterized by the thermal decomposition of cellulose and hemicellulose. For ethanol and lactic acid-washed samples, the weight loss in the last stage decreased and the amount of the char residues increased, with the highest of 22.7% for the lactic acid-washed sample. Gas chromatography-mass spectrometry analysis of high-temperature pyrolysis oil showed that water pretreatment could effectively reduce the production of aromatics and cresols, while ethanol was able to elute chlorogenic acid, a precursor of hydroquinone. Lactic acid pretreatment increased the relative content of long-chain hydrocarbons and acids, causing the relative peak area percentages of n-hexadecanoic acid to increase from 1.8% to 8.91% compared with the raw sample of tobacco. In addition, organic solvent pretreatment promoted the formation of ketones in the pyrolysis oil and also inhibited the formation of substituted pyridines at the C-3 position on the pyridine ring.

Enhancement of renewable N-heterocycles production via catalytic co-pyrolysis of glycerol and cellulose over HZSM-5 under ammonia atmosphere

Catalytic pyrolysis of biomass for efficient N-heterocycles production is highly promising but extremely challenging. Herein, catalytic co-pyrolysis of glycerol and cellulose under ammonia atmosphere was proposed to enhance the N-heterocycles yield. First, a solvolysis effect of glycerol, which could improve the thermal depolymerization of cellulose, was observed in thermogravimetric analysis (TGA). After that, the major influential factors, including Si/Al ratio, reaction temperature, and glycerol-to-cellulose (Gly:Cel) ratio, were investigated systematically. The N-heterocycles yield, as well as the comprehensive synergies of feedstocks, reached their maximum value under the conditions of Si/Al = 85, 550 ℃, and Gly:Cel = 5:1. The best synergistic extents for pyrroles, pyridines, and indoles were 105.3%, 71.3%, and 38.8%, respectively. The mechanism insight showed that, the thermal decomposition of cellulose was promoted while the coking of oxygenated molecules was suppressed during the catalytic co-pyrolysis process. Consequently, more oxygenated molecules were generated and retained for further catalytic conversion into imine intermediates and N-heterocycles.

Experimental study on pretreatment effects of [BMIM]HSO4/ethanol on the thermal behavior of cellulose.

Ionic liquids (ILs) have been investigated to dissolve and/or pre-treat cellulose by combining with a low viscous co-solvent. Dissolution and pretreatment of cellulose by ILs are dynamic processes of dissolution and precipitation, which would caused the physical and chemical changes (such as crystallinity and thermal stability) of un-dissolved cellulose residues. Hence, this study focused on the thermal behavior of un-dissolved cellulose (PCEL) after pre-treatment using [BMIM]HSO4/ethanol. Ethanol was used as a green and cheap co-solvent of 1-butyl-3-methylimidazolium hydrogen sulfate ([BMIM]HSO4) to pre-treat cellulose under different conditions. The pretreatment effect on thermal behavior of PCEL was investigated by thermogravimetric analysis and the distributed activation energy model. [BMIM]HSO4/ethanol pretreatment efficiently lowered the thermal stability of cellulose, and promoted the thermal decomposition at low temperature. The thermal behavior of PCEL can be adjusted by the [BMIM]HSO4 mass concentration.

Kinetic Study of Paper Waste Thermal Degradation

Paper waste generation has been rising in the past decades, with a large amount being landfilled. These paper wastes can be great energy sources after thermal treatment since they are considered carbon neutral. These wastes contain mainly cellulose, hemicellulose, lignin, and some minerals. The thermal decomposition of cellulose, hemicellulose, and lignin have been extensively studied, however, the knowledge of thermal degradation of paper wastes at lower temperatures, which are more practical for industrial applications are still lacking. In this study, paper wastes have been characterized and thermogravimetric analyses were performed from 200°C to 400°C and the char produced were analyzed by nuclear magnetic resonance (NMR) spectroscopy and Fourier-transform infrared (FTIR) spectroscopy. Two kinetic approaches were taken while developing the kinetic model of paper waste thermal degradation: (i) reconstructing the TGA results of paper waste thermal degradation by an additive law of the degradation of cellulose, hemicellulose and lignin; (ii) considering paper waste as one material and develop a multi-step consecutive reaction mechanism that focuses on solid products at different temperatures. It was observed that there are potential interactions between cellulose, hemicellulose and lignin during paper waste degradation. Therefore, the second approach was concluded to be more plausible, and one set of kinetic parameters were determined according to the experimental results at different temperatures. These results provided insights into the degradation kinetic mechanism and solid product distribution of the paper waste. It was found that the first reaction was due to dehydration of cellulose and the 6th and 7th reaction can be attributed to the thermal degradation of lignin. The NMR and FTIR results also validated that the cellulose started degrading at lower temperatures, and lignin degradation became more pronounced at higher temperatures.

Quantification of persistent free radicals (PFRs) formed in thermally decomposed cellulose and its correlation with residual carbon amount

Thermal decomposition of cellulose was carried out in a tubular reactor under flowing argon gas at 573, 673 and 773 K. The loss of carbon, hydrogen and oxygen was observed, and enhanced with increase in temperature continuously. The persistent free radicals (PFRs) were not observed in the sample decomposed at the lowest temperature of 573 K, and observed in the samples decomposed at higher temperatures of 673 and 773 K. This incontinuous trend was discussed from viewpoints of radical formation and its stabilization during the thermal decomposition. An empirical correlation between PFR density and residual carbon amount was proposed.

Bio-Composites Consisting of Cellulose Nanofibers and Na+ Montmorillonite Clay: Morphology and Performance Property

This paper reports the usage of cellulose nanofibers (CNFs) as a continuous nanoporous matrix and nanoclay (NC) as additive to fabricate hybrid films. CNF/Cloisite Na+ nanoclay composite films containing 10–50 wt % of NC were prepared for the study. The effects of NC incorporation and its content on mechanical, wettability and thermal degradation properties were investigated. The results showed that the film had a multilayer structure with gradually deposited CNT-NC hybrid on the filter paper Pure CNF films had higher moduli compared with those from the composite films, as the incorporation of NC decreased hydrogen bonding and networking ability of CNFs, especially at the high NC loading levels. The composite films demonstrated self-extinguishing ability when being exposed to the open flame. Composites with over 35 wt % NC did not burn because of the formation of a protective barrier containing ordered NC platelets. The addition of montmorillonite NC led to increased surface water contact angle, showing enhanced hydrophobicity of the material. During the film’s thermal pyrolysis, the first process occurred between 100 and 200 °C, resulting mainly from the evaporation of absorbed water; the second, between 280 and 350 °C, indicated thermal decomposition of cellulose; and the slow third stage happened from the 350 to 600 °C, representing carbonization. The results demonstrate that the apparent activation energies for all the CNF/NC composites were higher than the pure CNF film. CNF/NC films fabricated in this process are a promising barrier material for packaging applications.

Pine Wood Particles Pyrolysis and Radiographic Analysis

The goal of this experiment is to assess the mass and volume loss of medium size pine wood particles undergoing pyrolysis. Wood samples of different sizes and shapes were pyrolysed at 500 ºC with different residence times. A thermogravimetric analysis was carried out for comparison purposes. Finally, the pyrolysed samples were analysed using radiographic methods. A connection between the different analyses was found. For larger particles, the heating rate is lower, and a time gap between hemicellulose and cellulose thermal decomposition was noticed. Research shows that an important part of the analysis of the process is the rate of biomass heating and sample size. As the sample size increases, the pyrolysis time increases; however, the increase is not linear. The publication also shows the great possibilities of radiographic methods in analysing the pyrolysis process.

Influence of temperature and time on initial pyrolysis of cellulose and xylan

The aim of this study was to investigate the effects of temperature and reaction time on the primary pyrolysis of cellulose and xylan. Fast pyrolysis of cellulose and xylan was carried out with a micropyrolyser connected to a gas chromatograph-mass spectrometer/flame ionisation detector (GC–MS/FID) to separate and identify volatile components, both qualitatively and quantitatively. This set-up meant a minimum amount of secondary reactions, low impact of the heating period and at the same time provided rapid and accurate analyses. The two biomass components investigated were: cellulose and hemicellulose (represented by xylan). They were pyrolysed during 0.5, 1, 2 and 5 s (s) and within a temperature range of 400–600 °C. The results showed that levoglucosan (1, 6-anhydro β-D-glucopyranose) is the main chemical compound released during cellulose pyrolysis. It increased with increasing temperature and time. The main volatile compounds produced from pyrolysis of xylan are: 1-hydroxy-2-butanone, 4-hydroxy-5, 6-dihydro-(2 H)-pyran-2-one, 1-hydroxy-2-propanone (acetol), acetaldehyde and hydroxyacetaldehyde (HAA). HAA was the most abundant chemical compound released during xylan pyrolysis, increasing with higher temperatures and time. Acetol and acetaldehyde also showed similar behaviour. The chemical compounds released from cellulose and xylan fast pyrolysis are primary products and assumed to be produced directly from both cellulose and xylan molecules and not from secondary degradation. In this study, possible reaction routes during biomass primary pyrolysis are also suggested based on the product distribution from the thermal decomposition of cellulose and xylan.

Composition of organic compounds from low-temperature burning of lignite and their application as tracers in ambient air

Levoglucosan, a product from thermal decomposition of cellulose, is widely known as an organic tracer of biomass burning, but has also been reported from coal smoke particulate matter (PM) including lignites. This study provides direct evidence that levoglucosan is generated not only during low-temperature burning/smoldering of xylite, but also from other lignite types including detritic and detroxylitic brown coals from Poland. Moreover, only trace amounts of mannosan and galactosan have been detected in PM of lignite smoke. The hopanes in lignite smoke PM comprise the thermodynamically unstable ββ-hopanes and hopenes, with values of the homohopane index 22S/(22S + 22R) ranging from 0.02 to 0.12. This is characteristic for immature organic matter, and combined with the presence of anhydrosaccharides can be used as tracers for lignite combustion in ambient air. Furthermore, almost all Miocene lignite smoke PM samples contain α-, β-, γ-, and δ-tocopherols, and prist-1-ene. This is the first report of the occurrence of all four tocopherol isomers in the geological record (in lignite extracts) and in lignite smoke PM samples. Lower α-tocopherol is observed for the lignite burn-test samples than in the corresponding lignite extracts, probably due to partial chain degradation to prist-1-ene during combustion.

Microscopic Mechanism of Cellulose Bond Breaking and Bonding Based on Molecular Dynamics Simulation

The ReaxFF molecular dynamics simulation and Monte Carlo method were adopted to analyze the pyrolysis process of cellulose in insulating papers from the perspective of microscopic atom. Molecular dynamics failed to continuously describe the motion behavior of an atom. According to this principle, the system can only calculate the atomic state on the node and then move the atom by a time step to continue calculating the atom. This paper would put forward the optimal step setting method of cellulose thermal decomposition in insulating paper: setting one step every other 0.1 fs. Specifically, for small molecules with a simple structure, such as H2O, the step size was set to 0.4 fs or less, while the step size of macromolecules with complex structures (CH2O2) should be set to 0.2 fs or less. In addition, the relationship between the step size and the temperature to which the system was heated was given as well in this paper. In previous literatures, empirical values were used to set the step size. This study would not only provide a theoretical basis for the study on the bond formation and fracture process of cellulose pyrolysis products, but also offer the data and guidance for related fields in the future, thus rendering an efficient simulation process.

Numerical Modelling of a Fast Pyrolysis Process in a Bubbling Fluidized Bed Reactor

In this study, the Eulerian-Granular approach is applied to simulate a fast pyrolysis bubbling fluidized bed reactor. Fast pyrolysis converts biomass to bio-products through thermochemical conversion in absence of oxygen. The aim of this study is to employ a numerical framework for simulation of the fast pyrolysis process and extend this to more complex reactor geometries. The framework first needs to be validated and this was accomplished by modelling a lab-scale pyrolysis fluidized bed reactor in 2-D and comparing with published data. A multi-phase CFD model has been employed to obtain clearer insights into the physical phenomena associated with flow dynamics and heat transfer, and by extension the impact on reaction rates. Biomass thermally decomposes to solid, condensable and non-condensable and therefore a multi-fluid model is used. A simplified reaction model is sued where the many components are grouped into a solid reacting phase, condensable/non-condensable phase, and non-reacting solid phase (the heat carrier). The biomass decomposition is simplified to four reaction mechanisms based on the thermal decomposition of cellulose. A time-splitting method is used for coupling of multi-fluid model and reaction rates. A good agreement is witnessed in the products yield between the CFD simulation and the experiment.

Effect of the reduced-graphene oxide on the structure and thermal properties of compoiste PMMA/micro-cellulose fibers from petioles of Vietnamese nipa palm tree

This study separated and treated successfully micro-cellulose fibers from petioles of Vietnamese nipa palm tree (tCell) by simple mechanical and chemical methods. The combination of the treated micro-cellulose fibers and reduced-graphene oxide by hydrazine hydrate (tCell-RGO) increases the thermal stability and the glass transition temperature of polymethylmathacrylat (PMMA) in synthesis composite by in situ emulsion method. The study improves the environmental friendliness of PMMA and overcome the disadvantages of low thermal decomposition of cellulose in preparation of polymer composites, especially kinds of heat-stable polymers as PMMA.

Cellophane and filter paper as cellulosic support for silver nanoparticles and its thermal decomposition catalysis

Silver nanoparticles (AgNPs) have attracted great attention due to its optical, electrical and thermal properties. Cellulosic supports for these nanoparticles are of particular interest because of its availability, flexibility and biocompatibility. In this work, AgNPs were synthesized using two cellulosic materials, cellophane (CP) and filter paper (FP), as matrix support. Cellulosic materials were immersed in an aqueous solution of silver nitrate containing polyvinylpyrrolidone (PVP) and then reduced with hydroxylamine. The obtained nanocomposites (CP-AgNPs and FP-AgNPs) were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (DRX) and scanning electron microscopy (SEM). AgNPs of near 15nm anchored onto cellulosic surfaces were detected. The thermal properties of these materials were investigated through thermogravimetry (TG). Their kinetic of thermal decomposition was studied by the Vyasovkin method of dynamic isoconvertion, which indicated a catalytic effect of AgNPs in the cellulose thermal decomposition reaction.

Thermal Behavior of Used Alkaline Primary Button Batteries Disposed as General Waste

The thermal behavior of new (1.5 V) and used (0 V) primary LR1130 alkaline button batteries was investigated by thermogravimetric differential thermal analysis (TG/DTA). The anode (MnO2) and cathode (Zn) from the batteries were mixed with paper or plastic (1:1). Cellulose and polyethylene were used to represent paper and plastic, respectively. The thermal behavior of MnO2, Zn and the separator from both new and used batteries was comparable by TG/DTA using. There was no exo- or endothermic decomposition of Zn and minor exothermic decomposition of MnO2 from new and used batteries. MnO2 and Zn were markedly affected by the thermal decomposition of cellulose. However, cellulose mixed with MnO2 was more of a thermal hazard than when mixed with Zn. Moreover, MnO2 and Zn from both new and used batteries were also affected considerably by the thermal behavior of polyethylene. Therefore, the accidental disposal of used alkaline button batteries shows high potential to lead to an accident.

Radiation-induced high-temperature conversion of cellulose.

Thermal decomposition of cellulose can be upgraded by means of an electron-beam irradiation to produce valuable organic products via chain mechanisms. The samples being irradiated decompose effectively at temperatures below the threshold of pyrolysis inception. Cellulose decomposition resembles local “explosion” of the glucopyranose unit when fast elimination of carbon dioxide and water precede formation of residual carbonyl or carboxyl compounds. The dry distillation being performed during an irradiation gives a liquid condensate where furfural and its derivatives are dominant components. Excessively fast heating is adverse, as it results in a decrease of the yield of key organic products because pyrolysis predominates over the radiolytic-controlled decomposition of feedstock. Most likely, conversion of cellulose starts via radiolytic formation of macroradicals do not conform with each other, resulting in instability of the macroradical. As a consequence, glucosidic bond cleavage, elimination of light fragments (water, carbon oxides, formaldehyde, etc.) and formation of furfural take place.

Regulation of atmospheric carbon dioxide by vegetation fires

CR Climate Research Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials CR 59:125-133 (2014) - DOI: https://doi.org/10.3354/cr01210 AS I SEE IT Regulation of atmospheric carbon dioxide by vegetation fires Rowena Ball* College of Physical and Mathematical Sciences, Building 27, The Australian National University, Canberra 0200, Australia *Corresponding author: rowena.ball@anu.edu.au ABSTRACT: Vegetation fires release some fraction of the carbon in the biomass back to the atmosphere as CO2 and deposit some of the carbon onto the ground as charcoal or pyrogenic carbon. It is an open, but not unanswerable, question as to whether the formation of pyrogenic carbon can effectively sequester carbon from atmospheric CO2. The purpose of this article is to conceptualise the question in terms of the global Charcoal Challenges, which deal with the scientific and socioeconomic questions associated with increasing the refractory (or long-term) black carbon pool at the expense of the atmospheric carbon pool, and to investigate the formation and decay of charcoal within this paradigm. Three particular Charcoal Challenges are examined: (1) the feasibility of lowering atmospheric CO2 by biochar production, (2) the tension between nature’s use of fire to distribute carbon between long-term black carbon and short-term atmospheric pools and humans’ need to suppress fire and (3) the premise that black carbon is a sink for CO2 only if its rate of formation exceeds its rate of decay; otherwise, it is a source. I show how the thermal decomposition of cellulose, the major constituent of vegetation, during fires acts as a thermokinetic oscillator that regulates the global distribution of carbon between atmospheric and black carbon reservoirs. I conclude that we cannot yet assume with certainty that the global black carbon reservoir is a carbon sink. KEY WORDS: Pyrogenic carbon · Charcoal · Vegetation fires · Carbon sink · Thermokinetic oscillator Full text in pdf format PreviousNextCite this article as: Ball R (2014) Regulation of atmospheric carbon dioxide by vegetation fires. Clim Res 59:125-133. https://doi.org/10.3354/cr01210 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in CR Vol. 59, No. 2. Online publication date: March 05, 2014 Print ISSN: 0936-577X; Online ISSN: 1616-1572 Copyright © 2014 Inter-Research.

Thermogravimetric and calorimetric study of cellulose paper at low doses of gamma irradiation

The study of the behaviour of cellulose materials at low doses of ionizing radiation regained the interest because of the recent results showing that physical properties of the paper have less or no changes for absorbed doses below 10 kGy, despite the high decrease of the degree of polymerization. The understanding of the relationship among molecular, microscopic and macroscopic changes in cellulose materials may change the current opinion that irradiation of paper is not the best choice for conservation of cultural heritage. The aim of this study is to reveal the changes in gamma-irradiated pure cellulose paper by simultaneous TG/DSC analysis. For cellulose fibres, the thermal decomposition parameters depend on the cellulose degree of polymerization. For high irradiation doses, there is established a relationship between the absorbed dose and the degree of polymerization. However, a direct relationship between absorbed dose and the parameters of cellulose thermal decomposition for low irradiation doses was not established either in the literature or in our study. By using a peak separation technique, we studied the changes in the region of water loss (70–150 °C) and physical ageing (160–300 °C) for Whatman paper with low initial water content (<1 %), previously gamma irradiated at doses between 0 and 30 kGy. We concluded that strength of the hydrogen bond structure is increasing up to a point when the stress produces fractures in the fibrilar structure. This may explain the results reported for mechanical tests at low dose irradiation and it is in agreement with scanning electron microscopy pictures showing changes in fibril structure at high irradiation doses. Cellulose irradiated at low doses maintains its original hydrogen bond structure despite the decrease of the degree of polymerization.

Bio-oil production by fast pyrolysis of cellulose/polyethylene mixtures in the presence of metal chloride

Cellulose/polyethylene mixture (3:1 w/w) and Tetra Pak wastes with and without metal chloride (ZnCl2, AlCl3, CuCl2, FeCl3) addition were subjected to a fast pyrolysis process at 350–500 °C and heating rate 100 °C/s to evaluate the possibility of liquid product formation with a high yield. The addition of zinc, aluminum, iron and copper chlorides has influenced the range of samples decomposition as well as the chemical composition of resulting pyrolytic oils. It was found that formation of levoglucosan, the main product of cellulose thermal decomposition, and phenol and its derivatives decreased in a presence of metal chlorides. Non-catalytic fast pyrolysis of polyethylene leads to the formation of solid long chain hydrocarbons, whereas the addition of metal chlorides promotes the formation of more liquid hydrocarbons.

Effect of Transition Metal on the Thermal Degradation of Cotton Cellulose Modified with THPC

The thermal decomposition of cellulose treated with tetrakis(hydroxymethyl) phosph- onium chloride (THPC), urea and ammonium dihydrogen phosphate (ADP) and its metal complexes was studies by TG, DTA and CONE. The activation energies for the second stage of thermal degradation have been obtained by following the Broido equation. Experimental data show that for the complexes of cell-THPC-urea-ADP with metal ions, the activation energies and thermal decomposition temperatures are higher than those of cell-THPC-urea-ADP, which shows these metal ions can increase the thermal stability of cell-THPC-urea-ADP. Moreover, Ni(Ⅱ), and Zn(Ⅱ) can more increase thermal stability of samples than Co(Ⅱ). The CONE data indicate that the transition metals have smoke suspension on cell-THPC-urea-ADP. Moreover, Co(Ⅱ) has more effect than Ni(Ⅱ), and Zn(Ⅱ) in the smoke suspension.

Thermogravimetric characterization of dairy manure as pyrolysis and combustion feedstocks

Thermogravimetric analysis was used to examine the thermal behavior of dairy manure as a pyrolysis and combustion feedstock. Nitrogen and air were used as purging gases to analyze the pyrolysis and combustion reactions, respectively, and heating rates of 20°C min(-1), 40°C min(-1) and 60°C min(-1) were applied. An Arrhenius model was used to estimate the kinetic parameters (activation energy, reaction order and pre-exponential factor). Results showed four steps for both the pyrolysis and the combustion reactions, with the second step being the most critical one and during which most thermal decomposition of cellulose, hemicelluloses, starch and protein occurred. Thermochemical reactions were determined mainly by temperature. Heating rate influenced the start and the end of the thermal conversions. The activation energies for the two major reaction zones were 93.63 kJ mol(-1) and 84.53 kJ mol(-1) for pyrolysis, and 83.03 kJ mol(-1) and 55.65 kJ mol(-1) for combustion. Knowledge of the thermal behavior of dairy manure provides guidelines for future energy utilization.