Ammoxidation of kraft lignin was carried out in a Parr reactor using (15)NH(3) as the main nitrogen source. Reaction parameters were set up until a total nitrogen content of approximately 13 wt.% in lignin was achieved, in accordance with conditions of previous studies. Analytical tools such as FTIR, Py-GC/MS, and solid state NMR were used in this research. The nature of nitrogen bondings is discussed. The incorporation of the (15)N from ammoxidized lignin was followed in pumpkins (Zucchini cucurbita pepo L.) by means of (15)N emission spectroscopy.

FTIR spectra of spruce, beech, and bamboo MWL's, representing G, GS and HGS lignins, were recorded and examined in the wavenumber range of 1800 to 700 cm−1. The spectra were then submitted to a mathematical self-deconvolution technique in order to resolve the intrinsically overlapped bands. The same procedure was carried out with the IR spectra from two G and two GS dehydrogenation polymers (DHP's) prepared by the “zutropf” (ZT) and “zulauf” (ZL) polymerization method. Thus, approx. 30 bands typical for lignins and lignin-like polymer models were detected in contrast to standard spectroscopic conditions, which render visible 15 to 17 broad bands. Hidden bands, usually visible as shoulders, came to light, i.e. the apparent resolution was increased considerably by deconvolution. The deconvolved spectra are standardized and depicted in the absorption mode together with the original spectra. The wavenumbers and intensities of 54 bands apparent after deconvolution are compiled in a Table to render possible a direct comparison of the IR characteristics of lignina and DHP's. A difference spectrum obtained by subtraction of a G ZT DHP spectrum from a spruce MWL spectrum illustratea the differences between these polymers.

Cork from Douglas-fir bark (Pseudotsuga menziesii) was separated, extracted and submitted to suberin depolymerization by transesterification with sodium methoxide in methanol. As a result a saponified cork fraction (corksap) with a yield of 19% was obtained. From corksap a milled cork lignin (MCLsap) was isolated using the Björkman procedure with a yield of 0.75% (based on corksap, corresponding to 0.14% based on original cork). The isolated Douglas-fir MCLsap was characterized by elemental analysis and OMe determination, FT-IR spectroscopy and analytical pyrolysis (Py-GC/FID). Data are presented in comparison with those of MCLsap isolated from cork-oak (Quercus suber) and milled wood lignins (MWL) of spruce. All data revealed that the Douglas-fir cork lignin has a guaiacyl-type structure (G-lignin). Results of Py-GC/FID demonstrate that this polymer consists of approximately 97% guaiacyl, 2% p-hydroxyphenyl and 1% syringyl units.

The present work is devoted to the estimation of the effect of phosphoric acid and Fe3+ ions on the 1,6-anhydrosaccharides levoglucosan (LG) and levoglucosenone (LGone) contents in volatile products obtained from wood and microcrystalline cellulose by analytical pyrolysis. It was shown that the LG and LGone contents can be influenced by the pre-treatment. Iron was introduced into the biomass either by soaking in iron(III) sulfate solution alone or in the presence of ammonium, a treatment, in the course of which iron oxihydroxide is formed. It was demonstrated that a previous decationization of wood plays an important role for the subsequent results of Fe3+ ion treatment.The 1,6-anhydrosaccharides content in volatile products and the ratio of LG/LGone is governed by the phosphoric acid concentration. The same is true for cellulose soaked by iron sulfate: at higher concentration, the LGone content increases and the LG/LGone ratio decreases. The mechanism of the action of iron ions depends on the iron species formed upon the cellulose-containing raw materials pre-treatment procedures with iron sulfate. Upon pyrolysis, the adsorbed iron sulfate increases the amount of both LG and LGone in volatile products through the acidic catalysis mechanism owing to sulfate anions activity. The pre-treatment by the ion-exchange method could be considered as an efficient technique for obtaining the biooil containing levoglucosan in high content: 44.8% from cellulose and 27.3% from wood. The results are interpreted based on the quantitative evaluation of the pyrograms and the ESR spectra of the treated wood. (C) 2005 Elsevier B.V. All rights reserved.

The causes of the exceptionally low natural durability of one individual plantation-grown teak tree from Panama were investigated. In durability tests with Coriolus versicolor (Leithoff et al. 2001) the heartwood of this tree had shown a mass loss between 32% und 43% while the reference material of a durable teak from Myanmar revealed only 2.3% up to 12.1% mass losses. Further studies on the antifungal effects of extractives of this specimen have been performed and the results compared with those of durable teak woods from the same plantation and from natural forests in Myanmar as well. As highest antifungal activity was found in the acetone/water extract, this extract will be analysed here in relation to the inhibitory effect of fractionated substances on mycelium growth of Coriolus versicolor ( white rot) and Coniophora puteana ( brown rot). In parallel studies Windeisen et al. ( 2003) surveyed the chemical composition of plantation-grown teakwood from the same origin in Panama.

Biomass was pre-treated with phosphoric acid and dried prior to analytical pyrolysis. The influence of pre-treatment parameters—i.e. concentration of phosphoric acid, its uptake by biomass, and drying temperature—upon the pyrolysis process of various cellulose containing raw materials has been studied. The concentration of the impregnation solution should be chosen according to the sorption capacity of the cellulosic feedstock. By varying the concentration of phosphoric acid, the pyrolysis of microcrystalline cellulose Thermocell™ may be directed toward elevated production of levoglucosan (40%) and levoglucosenone (34%). The protective role of lignin in birch wood towards the cellulose moiety is discussed in connection with radical scavenging properties of lignin. Birch wood treated with phosphoric acid solutions (having concentrations less than 2%) yields approx. 15% levoglucosan. At higher concentrations, a decline of the radical scavenging activity of lignin occurs, which increments the role of dehydration reactions, and, as a consequence, the formation of more levoglucosenone (17%).

SEC elution curves of spruce milled wood lignin (MWL) and guaiacyl lignin polymer models (G-DHPs) in N,N-dimethylformamide (DMF) exhibited a bimodal elution profile. Light scattering measurements indicated that these elution profiles were due to association effects between the molecules. This became apparent from the determination of high molar masses in the range 10(5)-10(8) g/mol. To study this effect, MWL and DHP were fractionated by precipitation in tetrahydrofuran (THF). The THF-insoluble fractions were found to be the fractions corresponding to the apparent high molar mass part of the DMF elution profiles. The THF-soluble fractions proved to be the less-associated fractions, with lower apparent molecular mass. The individual fractions proved to be rather stable in DMF. Accordingly, the bimodal elution profiles of the starting materials were not the result of an equilibrium between associated and molecular dispersed molecules but of different structures exhibiting a specific and stable association pattern. The different fractions were further characterised by SEC in THF after acetylation to determine molar masses in molecular disperse solutions.

Summary Residual lignins have been isolated by enzymatic hydrolysis from sulfite, kraft, ASAM and soda/AQ/MeOH pulps obtained both of spruce and beech wood. The protein content of the samples were in the range of 2 to 61 % and the carbohydrate content fluctuated roughly between 1 and 12 %. Seven of the isolates have been submitted to analytical pyrolysis (Py-GC/MS) aiming at the determination of the lignin composition in terms of 4-hydroxy-phenylpropane, guaiacylpropane, and syringylpropane units, referred to in the following as H, G, and S units. Pyrolysis of proteins leads mainly to phenol, cresol, and indole. Phenol and cresol of protein origin may influence seriously the H content determination of lignins. However, the contribution of protein to this compounds can be corrected successfully based on the intensity of the indole peak in the pyrograms. Nevertheless, the pyrolysis results should not be over-interpreted concerning the H contents in the case of samples heavily contaminated with proteins. As analytical pyrolysis overestimates the S content in a similar manner as the chemical degradation techniques do, an empirical correction equation was used to approximate the “true”" S content. Py-GC/MS gave systematic and reproducible differences between the residual lignins on the one hand, and the MWLs, which have been pyrolysed for comparison, on the other hand. The fingerprinting ability of analytical pyrolysis, the G/S ratios of beech residual lignins, and the unusual properties of ASAM residual lignins with their high S contents are discussed.

The effect of wood, cellulose, lignin and activated charcoal on the thermal decomposition of polystyrene (PS) and polyethylene (PE) has been studied in order to investigate the thermal behavior of these materials occurring in municipal waste. Thermogravimetry/mass spectrometry and pyrolysis–gas chromatography/mass spectrometry revealed that these materials had a similar influence on PS and PE thermal decomposition under slow and fast heating conditions respectively. The effect is related to the char-forming capability of the wood-derived additives; thus cellulose had the least and pure charcoal had the greatest influence on the decomposition of the polymers studied. Polystyrene is more sensitive to the presence of additives than the two PE polymers investigated. The thermal decomposition of PS shifts to higher temperature and the product distribution changes significantly in the presence of wood-derived additives. The yield of monomer, dimer and trimer decreases and the formation of other products (e.g. toluene, ethyl benzene and α-methyl styrene) increases. The effect of additives is interpreted in terms of the free radical mechanism of the thermal decomposition of PS. Wood, cellulose and lignin have a small effect on the thermogravimetric curves of PE. Charcoal promotes the hydrogenation of the unsaturated products and the hydrogenated products evolve at higher temperature.

This chapter contains section titled: Introduction Experimental Results and Discussion Conclusions References

Analytical pyrolysis combined with gas chromatography (Py-GC) has been used to study the composition of volatile products of different commercial celluloses impregnated with various amounts of phosphoric acid. The influence on the yields of levoglucosan and levoglucosenone was studied taking into account the supramolecular structure, degree of polymerization, hydrophilic properties and pretreatment conditions of the celluloses. It was found that levoglucosenone predominates in the volatiles of acid catalyzed pyrolysis. However, the relative total amount of both 1,6-anhydrosaccharides varied only in a narrow range of 75–85% regardless of the impregnation and pretreatment conditions of the celluloses. The maximum progress in cellulose dehydration reactions resulting in the highest levoglucosenone content of 78% is reached with Munktell microcrystalline cellulose owing to its low accessibility and high ordered supramolecular structure. For pulps with a less ordered cellulosic supramolecular structure, breaking of glycosidic bonds with the formation of levoglucosan besides levoglucosenone occurred and the relative amount of non-dehydrated anhydrosaccharides increased.

This work concerns studies on the thermocatalytic dehydration of “Taircell” cellulose from the sulphate pulping process and microcrystalline “Munktel” cellulose in order to obtain 1,6-anhydro sugars (levoglucosane and levoglucosenone) in high yields by flash pyrolysis. It has been shown that the heterogeneous interaction of cellulose with phosphoric acid begins with the impregnating step already at room temperature and continues during thermal treatment of cellulose. The maximal yields of levoglucosenone in flash pyrolysis were 25% (“Taircell”, 7% phosphoric acid, 100°C) and 30% (“Munktel”, 3.5% phosphoric acid, 100°C).

Biomass production of fodder sorghum (Sorghum sp.) has been tested in a field trial over two harvesting periods under natural meteorological conditions using ammoxidized kraft lignin (AKL) as a slow-release fertilizer and urea as conventional reference. In the course of the first growth cycle, plants treated with urea gave higher biomass yields because of the better solubility of urea in the initial phase. However, during the second cycle AKL treated plants performed better than urea treated sorghum, indicating that nitrogen from AKL became readily available.

Thermal decomposition of polypropylene (PP) was studied in the presence of wood flour, lignin, cellulose and charcoal in order to understand the pyrolytic behavior of the mixture of these components occurring in waste. Thermogravimetry/mass spectrometry was applied for monitoring the weight loss and the product evolution profiles under slow heating conditions. The formation of oligomeric products was analyzed by pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). Since the charring reactions of wood are still proceeding during the PP decomposition, the interactions between PP and char devolatilization are expected to be rather pronounced. The effect of the freshly formed pyrolytic chars on the decomposition of PP was simulated by mixing PP with pure activated charcoal. Activated charcoal had the most significant effect on the decomposition profile and the product distribution of polypropylene. In the presence of charcoal the decomposition shifted to lower temperature and the DTG curve became broader. The presence of charcoal promotes the formation of monomer and dimer. The effect of wood flour, lignin and cellulose is less pronounced. Though the decomposition starts at lower temperature in the presence of these additives and the DTG curve became broader, the temperature of the maximum decomposition rate and the char yields did not change significantly.

wood samples with Klason lignin ranging from 16.5% to 24.5%, and acid soluble lignin 3.8%–5.7% (extractive free wood) were tested. The lignin absorptivities were measured using a MWL and samples with known Klason and total lignin content: values of 18.47 lg−1 cm−1, 20.77 lg−1 cm−1, 25.57 lg−1 cm−1 were obtained. When the lignin content is calculated based on the MWL absorptivity, results are approximately 3 abs.% higher than the lignin content determined by the standard acid method. The results of total lignin determination (Klason plus acid soluble) can be reproduced with high precision by the acetylbromide method.

High syringyl/guaiacyl ratios (S/G ratios) are advantageous for pulping. Analytical pyrolysis was applied to Eucalyptus globulus wood to measure S/G ratios and assess its potential in forest breeding programmes. Samples were collected from five trees of two provenances grown in three sites. After peak assignment, relative peak areas were calculated for carbohydrate, guaiacyl and syringyl type degradation products. Lignin derived products account on average for 21% of the total identified area. The average S/G ratio of trees was 2.0, ranging from 1.5 to 2.6. The analysis of variance for the S/G ratios showed that provenance and tree were highly significant sources of variation accounting for 48 and 27% of the variation, respectively. Site had no influence but ‘site×provenance’ interaction was significant and accounted for 16% of the variation. The error associated with the method represented only 6% of the variation. Analytical pyrolysis proved reproducible and sensitive for the measurement of the natural variability of E. globulus with regard to lignin composition. The pyrolytic determination of the S/G ratios is recommended as an evaluation trait in breeding programmes for pulpwood production.

The low-temperature pyrolysis process and dehydration reactions of cellulose impregnated with phosphoric acid (1–10 wt.%) have been studied. Based on the yield of pyrolytic water and alterations of glucopyranose units of cellulose, it has been confirmed that dehydrated cyclic structures are formed in the solid phase during cellulose pyrolysis in the temperature interval 200–250°C. Phosphoric acid also catalyzes the subsequent depolymerization process of the dehydrated cellulose giving rise to 20% (on cellulose) of levoglucosenone. The yield of levoglucosenone depends on the amount of phosphoric acid and the time of pyrolysis. Thus, the pathway of dehydration reactions can be controlled by variation of these two parameters.

Pyrolysis is the degradation of macromolecular materials with heat alone in the absence of oxygen. It has both analytical and applied aspects. The development of advanced fast pyrolysis processes for liquids production has gained much attention in the last decade, because they offer a convenient way to convert low value woody residues into liquid fuels and value-added products. This review describes the new pyrolysis reactors under development. The systems based on (bubbling) fluidized bed and circulating fluidized bed reactors are presented. Moreover, the principles of ablative pyrolysis techniques such as the rotating blade and rotating cone reactors including the vortex system are outlined and a vacuum pyrolysis system, a recent technical development, is also presented. The international activities within the International Energy Agency and European Union are shortly outlined with special emphasis on the chemical and physical properties of pyrolysis oils and the methods for their upgrading and utilization as fuel and chemical feedstock. The pyrolysis liquids obtained in a yield of ca. 70% (based on dry wood) are complex mixtures of oxygenated aliphatic and aromatic compounds. Their energetic utilization is being tested in burners, Diesel engines and turbines. Commercial applications exist in the field of production of food aromas. Emerging areas of utilization are: additives for flue gas cleaning of coal combustion; acetic acid for chip production; adhesives; fuel enhancers; specialty chemicals; and fertilizers.

Summary Quercus suber L. milled cork lignins obtained from extractive-free cork (MCL) and from saponified cork (MCLsap) were characterized by thioacidolysis and KMnO4 oxidation. These techniques and the previously used analytical pyrolysis revealed that cork contains a guaiacyl lignin (G lignin) with 94–96% guaiacyl-, ca. 3% syringyl-, and 2–3% of 4-hydroxyphenyl-propane units. The total yields of degradation products in thioacidolysis and KMnO4 oxidation experiments were lower in comparison to those of a spruce milled wood lignin (MWLspruce) suggesting a higher cross-linking in the G-lignin of cork. The higher frequency of “condensed” structures (having C-C or C-O-C linkages to aromatic rings) in cork lignin was also manifested in the relative abundance of various aromatic acids obtained by KMnO4 oxidation. The cork lignin (MCLsap) contains only low amounts (ca. 2%) of covalently bonded suberinic acids. Numerous free aliphatic suberinic acids were detected and identified in the ether soluble part of MCLsap. Ferulic acid was not liberated by thioacidolysis, pointing at an in situ acylation. We suggest that the major part of the aromatic domain in cork is a G-lignin but that it includes also another structural moiety with higher H-unit content and linked by thioacidolysis resistant bonds.

FTIR spectroscopy was used to quantitatively determine lignin in Eucalyptus globulus wood. A total of 40 wood samples from a 9 year old provenance trial was divided into two independent sets for calibration and validation. Lignin contents, as determined by the acetyl bromide method, ranged from 23 % to 34 % o.d. extractive-free wood. Spectra were recorded with the KBr pellet technique and twelve peaks between 1800cm(-1) to 800cm(-1) used for calibration by linear regression. The best calibration fit (R-2=0.98) was obtained with the 1505cm(-1) peak from lignin and the 1157cm(-1) peak from polysaccharides as a reference. The standard error of calibration (SEC), and the standard error of prediction (SEP) calculated with the validation set, were very low. A linear regression of FTIR measurements proved strong enough to predict lignin content with a very high coefficient of determination. The accuracy of FTIR techniques allows its use in large scale breeding programmes to assess wood lignin content with considerable less effort and shorter time than using wet-lab methods, once a reliable calibration is performed for the species.