Thermal Decomposition Of Wood Research Articles

Thermal Decomposition of Wood Treated with Silicates by Thermogravimetry–Mass Spectrometry

The thermal decomposition of wood treated with a series of silicates was characterized by thermogravimetric (TG) analysis, differential thermogravimetry (DTG), and thermogravimetry–mass spectrometry (TG–MS) analysis. The addition of these chemicals caused a decrease in the decomposition temperature, a reduction in weight loss, and an increase in the amount of char produced. The results showed that ion current intensity and ion peak area of the typical representatives of incombustible ion such as m/z = 18 and 44 MS signals were increased by the flame retardants but the inflammable ion such as m/z =12 and 28 MS signals were decreased at the meantime, which indicate that the flame retardants can significantly enhances the dehydration and inhibits the deploymerisation reaction of wood.

Study on the effects of flame retardants on the thermal decomposition of wood by TG–MS

Abstract The effect of three flame retardants, K2CO3, Na2SiO3·9H2O, and Na2B4O7·10H2O on the process and composition of volatile products of the thermal degradation of wood has been investigated by the thermogravimetric (TG), differential thermogravimetry (DTG), differential thermal analysis (DTA), and the synchronous thermogravimetry–mass spectrometry (TG–MS) analysis methods. The results showed that the ion current intensity and ion peak area of m/z = 18 and 44 MS signals were increased by the flame retardants but the ion peak area of m/z = 28 MS signal was decreased (except K2CO3) at the meantime. What's more, the ion current intensity and ion peak area of m/z = 60 and 68 MS signals were also decreased (except K2CO3), which mean that Na2B4O7 can significantly enhances the dehydration and inhibits the depolymerization of wood. Although K2CO3 accelerates the dehydration reaction, it cannot inhibit the depolymerization reaction effectively, so the flame retardant efficiency of K2CO3 is decreased with the ...

In Vitro Studies on the Genotoxic Effects of Wood Smoke Flavors

Smoke flavors based on the thermal decomposition of wood have been applied to a variety of food products as an alternative for traditional smoking. Despite its increasing use, the available genotoxicity data on wood smoke flavors (WSF) are still controversial. Thus, potential genotoxic effects of WSF in four short-term in vitro genotoxicity assays were investigated, which included the Ames assay, chromosomal aberration assay, micronucleus test and the alkaline comet assay. WSF did not cause any mutation in the Ames assay using five tester strains at six concentrations of 0.16, 0.31, 0.63, 1.25, 2.5 and 5 µl/plate. To assess clastogenic effect, the in vitro chromosomal aberration assay was performed using Chinese hamster lung cells. No statistically significant increase in the number of metaphases with structural aberrations was observed at the concentrations of 1.25, 2.5, and 5 µl/ml. The in vitro comet assay and micronucleus test results obtained on L5178Y cells also revealed that WSF has no genotoxicity potential, although there was a marginal increase in micronuclei frequencies and DNA damage in the respective micronucleus and comet assays. Taken together, based on the results obtained from these four in vitro studies, it is concluded that WSF is not a mutagenic agent in bacterial cells and causes no chromosomal and DNA damage in mammalian cells in vitro.

Bio-energy in the black

At best, common renewable energy strategies can only offset fossil fuel emissions of CO2 – they cannot reverse climate change. One promising approach to lowering CO2 in the atmosphere while producing energy is biochar bio-energy, based on low-temperature pyrolysis. This technology relies on capturing the off-gases from thermal decomposition of wood or grasses to produce heat, electricity, or biofuels. Biochar is a major by-product of this pyrolysis, and has remarkable environmental properties. In soil, biochar was shown to persist longer and to retain cations better than other forms of soil organic matter. The precise half-life of biochar is still disputed, however, and this will have important implications for the value of the technology, particularly in carbon trading. Furthermore, the cation retention of fresh biochar is relatively low compared to aged biochar in soil, and it is not clear under what conditions, and over what period of time, biochar develops its adsorbing properties. Research is still n...

Thermal modification of OSB-strands by a one-step heat pre-treatment – Influence of temperature on weight loss, hygroscopicity and improved fungal resistance

Thermal modification of wood leads to improved resistance against fungal decay and decreased moisture uptake. Polyoses contribute most to the sorption behaviour of wood and act as main nutrition source for fungi. Thus, especially the conversion of polyoses has major impact on the degree of improvement. Thermal decomposition of wood is accompanied by weight loss. In this work the influence of temperature on weight loss, resulting equilibrium moisture content (EMC) and fungal resistance of OSB-strands is shown. It was found that EMC reaches a constant level, indicating completed reduction of free accessible hydroxyl groups. The levelling was ascertained to be irrespective of the temperature and duration of the pre-treatment. An improved fungal resistance according to durability class 3 and better was found for samples pre-treated above 200 °C. The presented correlation between reduced EMC and improved fungal resistance provides a tool for efficient determination of the durability of thermally modified wood.

TGA modeling of the thermal decomposition of CCA treated lumber waste

To guide the development of thermal decomposition methods for disposal of CCA treated wood, reactions during the thermal decomposition of CCA treated wood were modeled using thermogravimetric analysis (TGA), with special focus placed on arsenic volatilization. Simple inorganic compounds, such as As2O5, CuO, and Cr2O3, were used to model the thermal behavior of the inorganics in CCA treated wood. In air and nitrogen, arsenic (V) oxide began to volatilize at 600 °C during temperature ramps at 5 °C/min. During a 5 °C/min ramp in a hydrogen mix, arsenic (V) oxide began decomposition at 425 °C. Arsenic volatile loss from CCA treated wood can depend strongly on the gases produced by wood thermal decomposition. In the presence of As2O5, chromium (III) oxide and copper (II) oxide formed arsenates in air and nitrogen. Chromium arsenates began decomposition as low as 790 °C. This suggested that chromium arsenates in CCA treated wood formed during original preservative fixation may decompose as low as 790 °C. Copper arsenates were stable up to 900 °C in air, but showed only a limited range of stability in nitrogen. Depending on process conditions, the formation of copper arsenates may limit arsenic loss during thermal decomposition of CCA treated wood up to 900 °C. The thermal decomposition of inorganic oxides was influenced by interactions with wood and wood decomposition products. In a dry YP sawdust/As2O5 mix, arsenic (V) oxide volatilized at 370 °C during inert pyrolysis at 5 °C/min and at 320 °C during smoldering combustion at 5 °C/min. Thermal dwells of a dry YP/As2O5 mix showed no arsenic loss at 250 °C, but significant loss occurred during higher temperature dwells. During inert pyrolysis at 5 °C/min, the formation of complexes and hydrates were shown to prevent arsenic loss up to 400 °C.

Biomass conversion to liquid fuel by two-stage thermochemical cycle

The nature of wood thermal decomposition and notions about the influence of base effects have been studied in the presence of different solvents in the process of wood liquefaction. The possibility of consecutive stopped wood decompositions has been established according to the two competing directions: depolymerization and dehydration. The necessity of destructive processes and depolymerization of the biomass, which dominate over dehydration, has been shown to obtain liquid products (liquefaction products). The temperature limits of the depolymerization process (220–250°C), which precedes the two covered fields of eliminating water (240–280°C and 280–380°C), has been established. The possibility of obtaining light-boiling organic products ( T boil to 150°C) or a mixture of the light (∼150°C) and heavy (200–280°C) fractions has been shown to depend on the base concentration. At the same time, the nature of the deoxygenation processes of oxygen-containing pyrolysis products by dispersed iron has been studied.

Cellulose derived composites—A new method for materials processing

This research demonstrated for the first time a method for producing net shape polymer, ceramic and carbon composites using wood as a precursor. The conversion of wood to carbon has been practiced for centuries but the controlled thermal decomposition to form a monolithic carbon to be used as a template for composites as demonstrated by this research is a unique discovery. This was accomplished by thermal decomposition of wood under controlled conditions to produce a crack-free porous carbon monolith which was readily shaped by conventional methods. The shaped carbons have converted to carbon/polymer composites, carbon/carbon composites, ceramics, and ceramic composites without significant changes in dimensions. This research has demonstrated that composites derived from wood can eliminate several expensive processing steps. Specifically, no fiber lay-up or powder consolidation is required, and final grinding and polishing steps are minimized.

Thermal Decomposition of Wood and Cellulose in the Presence of Solvent Vapors

The thermal decomposition of white birch wood and filter pulp was studied in water and methanol vapor at 2 MPa pressure in a flow-through reactor. The abundance of the volatile products was monitored by on-line GC/MS using repetitive sampling in combination with fast separation on a short capillary column. The reactor was heated to 400 °C at 20 °C/min and the intensity profile of the product ions within the 30−200 amu range recorded. The system was capable of separating the profiles of typical hemicellulose products evolved at lower temperature from the characteristic cellulose and lignin products detected from wood. Char yields in methanol were similar to those in an inert gas atmosphere; however, the presence of water markedly increased the amount of char produced. The product distribution of cellulose was strongly affected by the solvents. In methanol, pyran derivatives dominate besides levoglucosan and glycolaldehyde, whereas the relative abundance of 2-furaldehyde and 5-(hydroxymethyl)-2-furaldehyde ...

Modelling of the pyrolysis of wet wood

The influence of moisture content on the thermal decomposition of wood has been analyzed. Using wood slabs, experimental results of temperature profiles and solid conversion for different moisture contents and heat fluxes have been obtained. A mathematical model without adjustable parameters was used to calculate the temperature at different points in the sample and the average total solid conversion. Once the validity of different assumptions of the model had been analyzed, the experimental results were compared with those calculated by the model. Acceptable agreement was achieved.

Angular and radial temperature profiles in the thermal decomposition of wood

During the thermal decomposition of wood, an increase in the particle size produces an important decrease in the weight loss of the solid caused by significant temperature profiles, both radial and angular, inside the solid. In order to determine these profiles, experiments with different particle sizes (2, 3, 4 and 5.6 cm in diameter) have been carried out. In these experiments, temperatures at different points corresponding to various values of radii and angles were measured. An analysis of the different values and trends obtained has been performed.

Thermal decomposition of wood in oxidizing atmosphere. A kinetic study from non-isothermal TG experiments

The kinetics of thermal decomposition of four wood species in oxygen-bearing atmospheres of 5, 10 and 20% molar O 2 concentrations have been studied from temperature-programmed experiments carried out at 5, 10 and 20 K min −1 heating rate. Devolatilization as well as combustion of the reamining solid have been considered to analyze the weight loss curves. The homogeneous volume reaction (VR) model has been used to describe devolatilization, whereas for solid combustion the grain model has been also checked. A two-stage approach has been used to fit the conversion-time curves and to derive the corresponding apparent kinetic parameters. The VR/VR (pyrolysis/combustion) combination provided a better description of the experimental α− t curves than the VR/grain combination. Holm oak and cork oak showed very close reactivities, whereas some differences were observed for aleppo pine and eucalyptus.

A kinetic study of holm oak wood pyrolysis from dynamic and isothermal TG experiments

The kinetics of holm oak wood thermal decomposition in a nitrogen atmosphere have been studied using dynamic and isothermal TG experiments. A number of different kinetic models are examined. Discrimination between the first order, second order and spherical symmetry boundary surface reaction models is difficult with the dynamic TG experiments. The isothermal weight loss curves obtained are best described by a first order rate equation.

A Mathematical Model of the Thermal Decomposition of Wood

Abstract A mathematical model developed for computer solution of heat transfer problems involving change of phase heat effects was applied to the prediction of transient temperature distributions and volatile product evolution rates in decomposing wood specimens. The required data input for the model was obtained directly from differential scanning calorimetric and thermal gravimetric measurements along with measured values of thermal conductivity A fast response electrical heater was designed to allow accurate specification of a constant heat flux boundary condition at the surface of a wood test specimen. Wood specimens were heated and partially decomposed while temperature profiles in the test specimen were measured with fine wire thermocouples. The measured temperature profiles, along with measurements of the weight loss of the heated specimen, were in good agreement with results predicted by the mathematical model. The model has several advantages over previous models, in that constancy of thermal pro...

Thermal decomposition of wood at temperatures up to 180° C—Part I: Stand of research

In der vorliegenden 1. Mitteilung wird ein Uberblick uber die grose Zahl von Veroffentlichungen gegeben, die sich meist mit Einzelerscheinungen und Teilgebieten der thermischen Zersetzung von Holz und seinen wichtigsten Bestandteilen Cellulose, Hemicellulosen, und Lignin, bei Warmebehandlungen unter Luftzutritt befassen.

Thermal decomposition of wood in an inert atmosphere

The thermal decomposition of wood has up to now been represented by an overall first order reaction with a definite heat of reaction. 1 There is now sufficient experimental evidence to show that such a treatment is too simple, since values obtained for activation energy and heat of reaction vary with experimental conditions. 2,3 The present paper describes a series of experiments in which cylinders of wood were decomposed under controlled heating conditions in an atmosphere of nitrogen in a furnace. During each experiment, the specimen was weighed continuously and its temperature was measured at several points. Data were analyzed in terms of the above theory to examine its validity and shortcomings.

Studies on carbonization of wood XIII On the difference of yield of acetic acid in the thermal decomposition of wood among the kinds of tree

Studies on carbonization of wood XIII On the difference of yield of acetic acid in the thermal decomposition of wood among the kinds of tree

L'Industrie chimique des bois: leurs dérivés et extraits industriels

Two distinct aspects of the technical chemistry of wood are dealt with in this book, namely, the working up of the volatile products from the thermal decomposition of wood and the preparation of tannin and other extracts from various classes of cellulosic materials. Unlike the majority of books of this nature, the authors have intentionally restricted theoretical descriptions and classification and have, so far as possible, concentrated on technical points and works' processes. In this way the maximum amount of information useful to the manufacturer has been secured, and general organic text-books can be consulted for the more theoretical underlying principles. L'Industrie chimique des bois: leurs derives et extraits industriels. Par P. Dumesny J. Noyer. Premiere partie: La distillation du bois; Deuxieme partie: Fabrication d'extraits divers. Deuxieme edition refondue et considerablement augmentee. Pp. vi + 432. (Paris: Gauthier-Villars et Cie; n.d.) 50 francs.

Distillation du bois

THE general treatment in this work is on somewhat similar lines to that followed in recent British and American text-books on the subject. Special attention is given to the distillation of resinous woods, and an interesting account of wood distillation plants is included, the text being made clear with numerous diagrams. There is a certain lack of proportion in the presentation of facts. Nearly one-third of the book is given over to ah account, such as is available in numerous organic text-books, of the elementary chemistry of acetic acid and methyl alcohol, and of simple derivatives of these, yet the study of the gaseous products from the thermal decomposition of wood is intentionally neglected. Again, the analytical section is considerably restricted. The space occupied by this important subject is only half that given to the preparation and properties of formaldehyde, and it is doubtful if the meagre information therein contained will be of much real value to the analyst. Distillation du bois. Par Prof. G. Dupont. (Encyclopédie Léauté, 2e série.) Pp. xv + 284. (Paris: Gauthier-Villars et Cie; Masson et Cie, 1924.) 25 francs.