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Highlights • Nitrogen-based blowing agents interact with cellulose during pyrolysis reactions. • Blowing agent reactions can yield biochar structures with nitrogen-doping. • N-doping is achieved with solid state additives in the absence of added gaseous NH 3. • Dicyandiamide decomposes into NH 3 , allowing for N-doping of cellulose char. Abstract Pyrolysis of cellulose mixed with blowing agent additives containing high nitrogen content has been investigated in this work. The additives used are dicyandiamide (DCD), 5-aminotetrazole (5AT) and 5-phenyl-1H-tetrazole (5PT), in concentrations of 0.25, 0.50, 1.0, 2.0 and 4.0% (weight). Blowing agents are of particular interest as a cellulose pyrolysis additive for two reasons: as a first case, if these additives and their decomposition products are chemically inert with respect to cellulose pyrolysis reactions, then they can serve to enhance the ejection of high-molecular weight aerosols from the liquid intermediate phase that is known to form during pyrolysis; as a second case, if these additives are not chemically inert, then the reactions between blowing agent decomposition products (e.g., NH 3 and HN 3) can provide a pathway by which nitrogen-doped carbonaceous char structures can be readily produced. Pyrolysis studies were carried out using thermogravimetric analysis and analytical Py-GC/MS of the pure compounds (DCD, 5AT, 5PT) and mixtures with cellulose, as well as proximate/ultimate analyses of the resulting chars from slow pyrolysis. Experiments showed that there is a reactive interaction between the additives and cellulose during pyrolysis, leading to greater char yields. Analysis of slow pyrolysis chars showed that DCD is promising for producing biochar with higher nitrogen content. This was attributed to the evolution of ammonia from DCD and due to its thermal decomposition occurring in a temperature range coincident with that of cellulose pyrolysis reactions. [ABSTRACT FROM AUTHOR]

N-doped carbons have significant applications in electronics, materials, and as tools for environmental services. However, few studies focus on N-containing compounds' carbonization strategies to increase char N retention. For this purpose, H 3 PO 4 and NaOH were used as additives during the co-carbonization of cellulose and four N-containing compounds (lysine, melamine, chitosan, and dicyandiamide (DCD)). Thermogravimetric and Py-GC/MS studies showed significant interactions between the N-containing compounds and cellulose with acid and basic additives. In all cases, an increase in char yield was observed. Acid-base treated samples were carbonized in a spoon reactor at 500 °C, and the resulting chars were thoroughly characterized. The maximum char yields were obtained in the presence of H 3 PO 4 due to the impact of this additive on cellulose dehydration. N's content in the char product varied from 2 to 12 wt. % depending on the N source. N conversion efficiency increases in the presence of H 3 PO 4. In the case of chitosan, we obtained N conversion efficiencies as high as 77 % in acidic conditions. The deconvoluted XPS N 1s spectra showed that each acid-treated char contained a dominant pyrrolic N form, likely due to the acid's effect on forming furanic compounds. NaOH-treated chars were richer in pyridinic structures. The first step in N-integration to biochar is the Maillard reaction. Carbonyls and amines react to form glycosylamine and the Amadori product. These intermediates form a Schiff's base of hydroxymethyl furfural in acidic conditions. In basic conditions, reductones are produced. These are important mediators of melanoidins. The melanoidins are subjected to aromatization and polycondensation reactions to form N-containing polyaromatic ring systems at high temperatures. [Display omitted] • H 3 PO 4) and NaOH additives modify the thermal behavior of cellulose/N-containing compounds blends. • The maximum char yield and N-conversion efficiency were achieved in the presence of H 3 PO 4. • H 3 PO 4 induces the formation of pyrrolic N in the char. • NaOH induces the formation of pyridinic structures. • The impact of H 3 PO 4 seems to be mediated by its impact on dehydration reactions. [ABSTRACT FROM AUTHOR]

N-doped carbons are widely studied due to their unique catalytic and adsorptive properties. However, the mechanism by which N from biological sources is integrated into carbonaceous materials is still poorly known. Advancing our understanding of these reactions is critical to designing N-doped carbons. The thermal behavior of cellulose, four N-containing model compounds (Lysine, Melamine, Chitosan, and Dicyandiamide (DCD), and blends of cellulose with 1–90 wt% of the N-containing compounds was studied. The prepared samples were examined by thermogravimetric analysis (TGA) and by Py-GC/MS. Our TGA results confirmed that the N act as a cross-linking agent, increasing char formation. Biochars produced in a spoon reactor were thoroughly characterized—the N content of the chars produced at 500 °C in blends of 16 wt% was between 4.3 and 12.4 wt%. N 1 s XPS confirms that most of the N in the chars produced was in the form of pyridinic N and pyrrolic N. The chars produced have a surface area between 218.5 and 364.6 m2/g. The main nitrogenated compound identified by Py-GC/MS during the pyrolysis of Melamine and DCD was NH 3. In addition to ammonia, these two molecules form aromatic ring systems rich in pyridinic moieties. When melamine is pyrolyzed, the small pyridinic ring systems are removed via evaporation. In the presence of cellulose, these pyridinic rings and those formed from DCD are integrated into the char structure. The lysine and chitosan pyrolysis form aminated compounds that react with carbonyl groups and eventually form pyrrolic char. N integration to char structure occurs when the reactive cellulose carbonyl groups react with amino groups through the Maillard reaction to form Schiff's base. A series of reactions follow, including decarboxylation, cyclization, and polymerization, creating N-heterocycle structures in char. [Display omitted] • The thermal behavior of cellulose and four N-containing compounds was studied. • N-acted as a cross-linking agent, increasing char yield in all the cellulosic blends. • Chitosan resulted in very high char yield and N conversion efficiencies. • All four N-containing compounds follow the Maillard reaction pathway to form nitrogen-containing char. • Lysine and chitosan co-pyrolysis with cellulose result in pyrrolic char. [ABSTRACT FROM AUTHOR]

Abstract: The production of bio-oil via the slow pyrolysis of dissolved air flotation (DAF) skimmings from poultry processing is described. The raw DAF skimmings were characterized for physicochemical properties and for thermal behavior (TGA). The bio-oil was produced in a batch pyrolysis system at varying temperatures between 400 and 700°C to study the effect of temperature on product yield. The fatty acids in the bio-oil produced displayed a high degree of saturation that caused the bio-oil to have poor cold flow properties (high cloud point and viscosity) so a solvent extraction scheme was devised to extract a bio-oil fraction rich in unsaturated fatty acids that could be further esterified into a bio-diesel and fatty nitriles that could be further processed into surfactants. This ethyl acetate-soluble fraction demonstrated much improved cold flow properties as well as lower water content and a higher HHV. The esterification of this soluble fraction was performed using methanol and sulfuric acid as an acid catalyst and the formation of fatty acid methyl esters was verified using GC/MS and FT-IR. [Copyright &y& Elsevier]

• Thermal pretreatment raises the softening point from 187 °C to 250 °C. • Organic and water soluble extractives do not act as plasticizers in the material. • Up to 50% of the weight of the sample can be volatilized during pretreatment. • Fixed C increases as a concentration effect rather than formation of new compounds. • Optimal processing time is 30 min at 300 °CB. Residues high in lignin and ash generated from the simultaneous saccharification and fermentation of corn stover were thermally pretreated in an inert (N 2) atmosphere to study the effect of time and temperature on their softening points. These residues are difficult to feed into gasifiers due to premature thermal degradation and formation of reactive liquids in the feed lines, leading to plugging. The untreated and treated residues were characterized by proximate and ultimate analysis, and then analyzed via TGA, DSC, 13C NMR, Py-GC–MS, CHNO/S, and TMA. Interpretation of the compositional analysis indicates that the weight loss observed during pretreatment is mainly due to the thermal decomposition and volatilization of the hemicelluloses and amorphous cellulose fractions. Fixed carbon increases in the pretreated material, mostly due to a concentration effect rather than the formation of new extra poly-aromatic material. The optimal processing time and temperature to minimize the production of carbonyl groups in the pretreated samples was 300 °C at a time of 30 min. Results showed that the softening point of the material could be increased from 187 °C to 250 °C, and that under the experimental conditions studied, pretreatment temperature plays a more important role than time. The increase in softening point was mainly due to the formation of covalent bonds in the lignin structures and the removal of low molecular weight volatile intermediates. [ABSTRACT FROM AUTHOR]

This study reports the impact of acid washing (to remove alkali and alkaline earth metals) followed by mild acid impregnation on the pyrolysis of Douglas fir wood. Dilute nitric acid was used in the washing and sulfuric acid, acetic acid, nitric acid, and phosphoric acid at acid loading levels of 0.05, 0.1, 0.3, and 0.5 wt.% were used for the acid impregnation to improve the yield of levoglucosan. A Py–GC/MS instrument was used to semi-quantitatively measure the impact of various acids and concentrations on the yield of low molecular weight compounds released during pyrolysis at 500 °C. The nitric acid wash removed 56% of the metal content. The results confirmed all the acids studied increased the production of levoglucosan, likely due to the mitigation of undesirable interactions between the cellulose and the other constituents of the lignocellulosic matrix. The highest yields of levoglucosan were achieved with the strong acids: sulfuric acid loading of 0.05 wt.%, nitric acid 0.05 wt.% and phosphoric acid 0.3 wt.%. Sulfuric and phosphoric acid also enhanced dehydration reactions in cellulose products and decreased the production of methoxylated phenolics from lignin. The very small range of concentration at which these acids increase levoglucosan yield makes it very difficult to control the process. In the case of acetic acid, it is not strong enough to catalyze dehydration reactions. Consequently a much wider range of concentrations can be used thus facilitating the control of the process. Acetic acid also does not affect the yield of lignin products. Therefore, acetic acid appears to be the most practical for acid impregnation (following mineral removal) in wood pyrolysis. [ABSTRACT FROM AUTHOR]

Torrefaction enhances physical properties of lignocellulosic biomass and improves its grindability. Energy densification, via fuel pellets production, is one of the most promising uses of torrefaction. Lignin contributes to self-bonding of wood particles during pelletization. In biomass thermal pretreatment, part of lignin (in the form of lignin liquid intermediates – LLI) migrates from the cell wall and middle lamella and deposits on the fibers’ surfaces and/or inner surface of the secondary cell wall. This material can play an important role on bonding particles during wood pelletization as well as production of wood composites. The objective of this paper was to investigate the influence of torrefaction conditions on amount, composition, molecular weight, and pattern of deposition of LLI on wood cells. Torrefaction of extracted ponderosa pine in the range of temperatures 225–350 °C was conducted in a tube furnace reactor and the torrefied wood was extracted with dichloromethane (DCM) to isolate the lignin-rich soluble material. A maximum yield of DCM-soluble material was observed in wood torrefied at approximately 300 °C for 30 min. ESI/MS revealed that the molecular weight of the removed material is less than 1200 g mol −1 and decreases as torrefaction temperature augments. Semiquantitative Py-GC/MS of the DCM-soluble material suggests that this lignin-rich material migrates and deposits on cells’ surfaces in amounts that depend on the torrefaction conditions. Py-GC/MS of the solid fraction after the DCM process showed a progressive reduction of products of the pyrolysis of lignin and levoglucosan as torrefaction temperature increased, revealing that lignin content in the solid decreased due in part to migration. SEM of torrefied particles helped to show the apparent formation of LLI during torrefaction. Results suggest that it is possible to control the thermal pretreatment conditions to increase or reduce the amount of lignin-rich material on fiber surfaces as required for downstream processes (e.g., fuel pellets or wood composites manufacture). [ABSTRACT FROM AUTHOR]

The aim of this paper is to improve the conversion of sugarcane bagasse to pyrolytic sugar levoglucosan through its pretreatment with acetic acid (10 wt.%) at 90 °C for 10 min under 200 rpm. Then, acid treated biomass was rinsed with deionized water to a neutral pH and dried in a vacuum oven at 70 °C up to constant weight. After acid treatment, the samples were subjected to fast pyrolysis in a Py-GC/MS. Thus, the impact of the acetic acid on the levoglucosan yield as well as other pyrolytic compounds released during pyrolysis process at different temperatures (from 350 to 600 °C) is reported. The best results respect to levoglucosan yield were attained when pyrolysis was performed at 400 °C resulting in around nine folds levoglucosan production from sugarcane bagasse after biomass treatment with acid compared to the control (untreated biomass samples) while the yield of some undesirable lignin derived compounds decreases in acid washed samples. The effect observed is due to the removal of the catalytic activity of alkali and alkaline earth metals. The attained results are very attractive because this pyrolytic sugar exhibits great potential as renewable feedstock for biofuels production and other bioproducts. [ABSTRACT FROM AUTHOR]

In this paper, the authors propose and evaluate a methodology to capture and visualize aerosols that are thermally ejected from the liquid intermediate of sugarcane bagasse and its pseudo-components (Avicel cellulose, Xylan and Organosolv lignin) pyrolysis. Tests were conducted on a hot plate reactor at 500 °C with two different pressures (150 mbar and 900 mbar) and two heating rates (10 °C/s and 1200 °C/s). The aerosols were collected on a heated slide located across from the sample. The slides were visualized with a scanning electron microscope (SEM) do determine the number and diameters of the droplets. Results showed that vacuum and the high heating rate (150 mbar and 1200 °C/s) favored thermal ejection of aerosols. The aerosol yield for sugarcane bagasse was lower to those obtained for cellulose and Organosolv lignin, and heating rate enhanced aerosol release more dramatically than pressure. [ABSTRACT FROM AUTHOR]

A mathematical model for biomass pyrolysis was proposed which couples mass and energy balances with the chemical reactions responsible for the generation of key species. The model includes volumetric particle shrinking and the explicit consideration of secondary reactions. Most importantly, for the first time this particle model includes the evolution of the liquid phase trapped within the solid and aerosol ejection due to bubbles bursting at the particle surface. Bubbles size distributions were estimated by population balances of dynamic bubbling in the liquid phase using the momentum method for calculations. The model was used to evaluate the effect of particle size, temperature, heat transfer coefficient, and reaction time on products distribution. Both bubble bursting and aerosol ejection intensity increased as particle thickness decreased and the heat transfer coefficient was augmented. The model shows how biomass thickness, external heat transfer coefficient, and temperature impact the yields of aerosols, char, and gas. The highest calculated yield of aerosols was 25 wt.% and was obtained with external heat transfer coefficients corresponding to fluidized bed (1000 W/m 2 K) with a 1 mm particle. At lower heating rates (50 W/m 2 K), the yields of aerosols (10–15 wt.%) were lower than those obtained at high heating rates. [ABSTRACT FROM AUTHOR]

Pyrolysis of lignocellulosic materials typically form carbonaceous residues (chars) with structures similar to the starting material. However, previous studies reported in the literature have shown that fast pyrolysis of cellulose and lignin form a molten intermediate liquid resulting in chars with smooth surfaces and evidences of intense bubbling. The fraction responsible for morphology conservation during pyrolysis is not known. In this article, pyrolysis visualization studies were carried out with a fast camera on cellulose, xylan, Organosolv lignin (OL), milled wood lignin (MWL), and lignocellulosic sugarcane bagasse to identify the component responsible for morphological conservation. The materials were heated using a modified Pyroprobe with measured sample heating rates close to 100 °C/s. Our studies confirm that cellulose, lignin, and deashed xylan are completely transformed into an intermediate liquid; the intensity of bubbling for lignin was far superior that of cellulose. Xylan as received, however, only forms a small amount of intermediate liquid; it does not fully melt and maintains its general shape during pyrolysis. These results suggest that the presence of mineral matter is critical for lignocellulosic materials to retain their original morphology. We repeated the studies on raw bagasse and acid washed bagasse. The raw bagasse retains its morphology; the acid washed bagasse shrank dramatically, but was not completely converted into a liquid. Our results suggest that in addition to hemicellulose with the presence of ash, other biomass fractions or the different temperatures at which the different fractions melt and solidify could also be contributing to maintain the structure of the lignocellulosic material during pyrolysis. [ABSTRACT FROM AUTHOR]

This paper reports studies on the film pyrolysis of sugarcane bagasse in an electrically heated hot plate reactor. The new experimental set up used is described. The bagasse studied was ground to particle sizes less than 37 μm (mesh 400) and was mixed with water to form the paste to be used to form the biomass film (10 mg of sugarcane bagasse distributed evenly on a steel plate, 60 μm thick). All the tests were conducted under vacuum (150 mbar). The effect of heating rate (between 5 and 1200 °C/s) and final temperatures (between 250 and 650 °C) on product yields (permanent gases, water, light volatile, pyrolytic lignin, sugars and char) were studied. The yield of fragmentation and dehydration products increased as heating rates augment. The effect of heating rate is only important till 100 °C/s, no significant changes in product yields are observed at higher heating rates. Bio-oils enriched in lignin and sugars oligomers were obtained at high temperatures and heating rates. These results suggest that good yields of fermentable sugars may be obtained in pyrolysis reactors working at intermediary pyrolysis conditions. [ABSTRACT FROM AUTHOR]

A new methodology has been proposed to describe of the dynamics of bubble formation during pyrolysis of Organosolv lignin and sucrose (surrogates for biomass) using fast speed visualization (125fps) with mathematical modeling. The model uses a population balance to predict overall rates of bubble birth and death, bubble bursting, and aerosol ejection. The experimental studies were performed on a uniquely modified CDS Analytical Pyroprobe 5000 to visualize the formation of bubbles within the liquid intermediate phase at heating rates close 100 °C/s. Experimentally, we observed that bubbles follow a log-normal distribution versus bubble size within the liquid intermediate phase for both materials. This distribution function changes over time due to increased viscosity from solidification reactions that generate char and the changes in the rate of bubble formation. Micro-explosion intensity was used to estimate aerosol ejection intensity. The model predicts aerosol ejection yields of 21.18% w/w from Organosolv lignin and 17.40% w/w from sucrose during pyrolysis with an average droplet size of 10 μm. [ABSTRACT FROM AUTHOR]

Two-step hydrotreatment experiments were performed using three completely different bio-oil fractions namely: whole bio-oil, heavy bio-oil obtained after fractional condensation of pyrolysis vapours and pyrolytic lignin obtained by cold water precipitation of the bio-oil. The aim is to study the de-oxygenation and in addition SEC and UV-fluorescence analysis was used to identify the importance of cracking, polymerization and hydrogenation reactions of the three different bio-oil feedstocks. In the first step hydrotreatment, Ru/C was used at 250 or 300 °C with reaction time of 2 h. In the second step hydrotreatment, Ni-Mo/Al 2 O 3 catalyst was used at 375 or 400 °C, with reaction time of 2 or 4 h. During stabilization in the first step, pyrolytic lignin was hydrogenated to a large extent accompanied by cracking reactions. In the second step, unsulphided Ni-Mo/Al 2 O 3 catalyst was active enough to effectively crack pyrolytic lignin into smaller molecules. High molecular weight compounds including large aromatic ring structures were formed from the reactive sugar rich fraction in both first step stabilization and second step hydrotreatment. The newly formed polymerization products were difficult to crack even at extended reaction times of 4 h at 400 °C. Importantly, the presence of water (and light oxygenates) could significantly supress the polymerization reactions. [ABSTRACT FROM AUTHOR]

Polyhydroxyalkanoate (PHA) production generates a significant amount of residual bacterial biomass (RBB) after PHA extraction. The RBB as a zero-value waste contains proteins, carbohydrates, phenolics, and ash, which can be managed and converted to bio-oil and biochar products by pyrolysis. Thermogravimetric analysis (TGA) was used to investigate the thermodegradation kinetics of RBB and pyrolysis–GCMS studies were employed to determine potential chemical products. Pyrolysis was conducted on a laboratory-scale auger reactor at 500 °C. The bio-oil and biochar yield were 28 and 46%, respectively. The pyrolysis bio-oil was characterized by the combination of GCMS, high-pressure liquid chromatography (HPLC), and electrospray ionization mass spectrometry (ESI–MS). The bio-oil was dominated by nitrogen-containing, hydrocarbons, and aromatic compounds. The biochar was studied for its specific surface area and pore size, chemical functionality by Fourier transform infrared (FTIR) and Raman spectroscopies, and butane absorption activity. Biochar was comprised of a large part of polycondensed phenolic and majorly disordered amorphous carbon. [ABSTRACT FROM AUTHOR]

The interactions between lignin and cellulose during the slow pyrolysis of their blends were studied by means of Thermogravimetric Analysis (TGA) and Scanning Electron Microscopy (SEM). Fast pyrolysis was studied using Pyrolysis-Gas Chromatography/Mass Spectroscopy (Py–GC/MS). Crystalline cellulose (Avicel), amorphous cellulose, organosolv lignin, and their blends containing 20, 50, and 80 wt.% of lignin were used for the experiments. Differential thermogravimetry (DTG) revealed that the interaction between crystalline cellulose and lignin resulted in a shift toward higher decomposition temperatures, but for lignin/amorphous cellulose mixtures this effect was small. No effect of adding lignin to cellulose was observed on the yields of bio-char. Cellulose-lignin interactions during fast pyrolysis in Py–GC/MS did occur. Products from cellulose fragmentation reactions (hydroxyl-acetaldehyde and acetol) were not influenced by the presence of lignin. In general, production of lignin derived phenolics remains quite similar at 500 °C, but the yield of many methoxylated monophenols increases at 350 °C in the presence of both types of cellulose. Importantly, it was found that the presence of lignin enhanced the yield of levoglucosan, but decreased the yield of some of their dehydration products (e.g., levoglucosenone, 5-Hydrosymethylfurfural, Furfural). This result could be explained by the reduction of residence time of cellulose products in liquid intermediates, a phase where most of the dehydration reactions occur. Lignin seems to enhance micro-explosions, decreasing in this way the residence time of cellulose derived products in the liquid intermediates. [ABSTRACT FROM AUTHOR]

This paper investigates the effect of pyrolysis temperature between 350 and 600 °C on the distribution of pyrolytic products derived from Avicel, α-cellulose, Douglas Fir wood (softwood) and Hybrid Poplar wood (hardwood) by Py-GC/MS as a way to identify the best conditions for bio-oil production. The products were grouped in five families depending on their origin. The C1 family is formed by products of cellulose fragmentation reactions (glycoaldehyde, acetol, 1,2-ethanediol, monoacetate, butanedial). The products grouped in the C2 family (levoglucosan, levoglucosenone, 1,4:3,6-dianhydro-α- d -glucopyranose) are derived from cellulose depolymerization reactions. The molecules derived from hemicellulose (acetic acid, furfural, 2-furanmethanol) were grouped in the H family. The products derived from lignin were grouped in two families L1 (derived from p-hydroxyl phenol (H) and guaiacyl (G) structures) and L2 (derived from syringyl (S) structures). Principal components analysis was used to identify the main factors controlling the distribution of products. Our results show that the yield of most of the pyrolytic products can be explained in the five groups or families described above. Most of the C1 products derived from Avicel, α-cellulose and Douglas Fir fragmentation reactions increase in yield as the temperature increases. In the case of Hybrid Poplar these products reach a maximum at 400 °C. CO 2 , 2-oxo methyl ester propanoic acid, 1,2-cyclopentanedione, 3-methyl, levoglucosenone, 1,4:3,6-dianhydro-α- d -glucopyranose, 2,5-dimethyl-4-hydroxy-3(2H)-furanone, and most of the phenolic compounds show a response to temperature changes that is independent of the feedstock processed. As the temperature increased the yield of levoglucosenone (product of dehydration reactions) decreased for all the samples studied. Levoglucosan yield is however highly dependent on the feedstock used and, as such, its behavior with temperature changes is more difficult to predict. The maximum yield of the products derived from lignin (L1 and L2) was found between 400 and 450 °C. [ABSTRACT FROM AUTHOR]

Highlights: [•] In acid washed samples, sulfuric acid seems to mitigate undesirable interactions between cellulose and the other wood constituents. [•] In acid washed lignocellulosic materials there is an optimal sulfuric acid concentration that results in a 50% increase in levoglucosan production. [•] Sulfuric acid affects the pyrolysis of raw and acid washed woody biomass. [•] Dehydration and polycondensation reactions are accelerated by sulfuric acid. [•] Cellulose fragmentation reactions are mitigated by the presence of sulfuric acid. [•] Sulfuric acid reduces the yield of methoxylated mono-phenols from lignin. [Copyright &y& Elsevier]

Abstract: The effect of cellulose crystallinity on the formation of a liquid intermediate and on its thermal degradation was studied thermogravimetrically and by Py-GC/MS using a control cellulose (Avicel, crystallinity at 60.5%) and ball-milled Avicel (low cellulose crystallinity at 6.5%). The crystallinity of the materials studied was quantified by XRD and FTIR. Thermogravimetric analyses (TGA) show the samples with lower crystallinity start to degrade at lower temperatures, exhibiting sharper DTG curves and lower thermal degradation activation energies. Scanning electron microscopy (SEM) studies of the solid residues formed in TGA tests showed that, while the conversion of the ball-milled cellulose (mostly amorphous cellulose) occurs through the formation of a liquid intermediate, in the conversion of the control the fibrous structure is conserved. Py-GC/MS studies showed major differences in the thermal behavior of the samples studied. At 300°C, amorphous cellulose yielded more levoglucosan. At temperatures between 350 and 450°C, higher yields of mono-anhydrosugars (levoglucosan and levoglucosenone) were obtained with the samples with higher crystallinity (control). The ball-milled cellulose produced more 5-(hydroxymethyl) furfural, 5-methylfurfural and furfural. The higher yields of these compounds are due to the acceleration of dehydration reactions when a liquid phase intermediate was formed. Fragmentation reactions responsible for the formation of light compounds (glycoaldehyde, acetic acid, methyl-vinyl-ketone and acetol) and the reactions responsible for the formation of cyclopentane do not seem to be affected by cellulose crystallinity and by the formation of a liquid intermediate. [Copyright &y& Elsevier]

Abstract: This paper reports the effect of pyrolysis temperature on the yield and composition of bio-oils obtained from the auger pyrolysis of Douglas Fir wood. The tests were conducted at reactor wall temperatures between 200 and 600°C. Due to the relatively low heat transfer rates achieved between the reactor wall and the biomass particles, the temperature of the solid residue obtained was much lower (between 117 and 420°C). Bio-oil yields were close (maximum yield: 59mass%) to those reported for fluidized bed reactors (more than 60mass%). The maximum oil yield was obtained at a reactor wall temperature of 500°C (biomass residue heated up to 328°C). At this temperature, maximum yields of Douglas Fir primary degradation products (lignin oligomers, anhydrosugars, 2-furaldehyde, 2(5H)-furanone, 2-furanmethanol, β-methoxy-(S)- and alkylated and methoxylated phenols) were observed. The yield of products from secondary thermochemical reactions (phenol; phenol, 4-ethyl, O-cresol; phenol, 3,4-dimethyl; cresol; pyrotechol, and phenol 2,4-dimethyl, methanol and gases) increased with temperature. In all cases, the yield of the products from secondary reactions was higher than those reported for fluidized bed reactors at comparable temperatures. The water yield (11mass%) obtained with the auger reactor was comparable to those reported for other materials processed in fluidized bed reactors. The results obtained confirm that the auger reactor is able to achieve good yields of both bio-oil and bio-char but that the overall composition of the oil obtained will be affected by the slower heating rates achieved and the intensification of secondary reactions in gas phase. [Copyright &y& Elsevier]