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Lipids are a biorefinery platform to prepare fuel, food and health products. They are traditionally obtained from plants, but those of microbial origin allow for a better use of land and C resources, among other benefits. Several (thermo)chemical and biochemical strategies are used for the conversion of C contained in lignocellulosic biomass into lipids. In particular, pyrolysis can process virtually any biomass and is easy to scale up. Products offer cost-effective, renewable C in the form of readily fermentable molecules and other upgradable intermediates. Although the production of microbial lipids has been studied for 30 years, their incorporation into biorefineries was only described a few years ago. As pyrolysis becomes a profitable technology to depolymerize lignocellulosic biomass into assimilable C, the number of investigations on it raises significantly. This article describes the challenges and opportunities resulting from the combination of lignocellulosic biomass pyrolysis and lipid biosynthesis with oleaginous microorganisms. First, this work presents the basics of the individual processes, and then it shows state-of-the-art processes for the preparation of microbial lipids from biomass pyrolysis products. Advanced knowledge on separation techniques, structure analysis, and fermentability is detailed for each biomass pyrolysis fraction. Finally, the microbial fatty acid platform comprising biofuel, human food and animal feed products, and others, is presented. Literature shows that the microbial lipid production from anhydrosugars, like levoglucosan, and short-chain organic acids, like acetic acid, is straightforward. Indeed, processes achieving nearly theoretical yields form the latter have been described. Some authors have shown that lipid biosynthesis from different lignin sources is biochemically feasible. However, it still imposes major challenges regarding strain performance. No report on the fermentation of pyrolytic lignin is yet available. Research on the microbial uptake of pyrolytic humins remains vacant. Microorganisms that make use of methane show promising results at the proof-of-concept level. Overall, despite some issues need to be tackled, it is now possible to conceive new versatile biorefinery models by combining lignocellulosic biomass pyrolysis products and robust oleaginous microbial cell factories., (Copyright © 2021 Elsevier Inc. All rights reserved.)

This paper explores the hyperbolic heat transfer effects in processes involving high heating rates. The behavior of the model is analyzed in detail under different boundary conditions and the circumstances under which a non-Fourier law could be used to describe thermal conduction processes established from physical mathematical analysis. Finally, the model developed here is coupled to a previous population balance framework to predict the bubbling phenomenon that occurs during the fast pyrolysis of biomass. We found that a transient overheating occurs in the central zone of the generated liquid phase due to the high heating rates that take place during that process. [ABSTRACT FROM AUTHOR]

Four principal intra-particle phenomena occur in a highly concerted manner during the pyrolysis of lignocellulosic materials: heat transfer, mass transfer, chemical reactions, and phase changes. Achieving a holistic understanding of these processes has been challenged by their intricate coupling, high temperatures, and rapid rates at which they occur. Heat and mass transfer have been well studied at the single-particle level but their coupling with chemical reactions and phase change within single particle models remains problematic. Equally challenging is the multiscale coupling of reactor- and single particle-scale models. Too little attention has been given to phase change. Similarly, the presence of oligomeric compounds (constituting up to 20% of the oil) has not been fully accounted for in chemical reaction schemes and physical models developed for pyrolysis. Recent studies have shown that a multiscale approach is key to predictive modelling across a variety of reactor systems. Historical and recent developments are outlined in this pyrolysis review paper regarding these four intra-particle phenomena, as well as modelling efforts to capture their effect on product yields and composition. It is critical for the design of future biomass pyrolysis systems to appropriately account for all four intra-particle phenomena and their inter-connectivities in order to predict, achieve, and maintain optimal operation. [ABSTRACT FROM AUTHOR]

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]

The effect of pyrolysis temperature on the morphology, bulk and surface chemistry of cellulose, xylan and lignin chars has been examined. Chars were produced between 300 and 700 °C. Raman, X-ray photoelectron, nuclear magnetic resonance spectroscopic techniques, scanning electron microscopy and surface area analysis were used to characterize each sample. Formation of polyaromatic structures were found to be prevalent at 400 °C for both cellulose and lignin chars, and showed development at 300 °C for Xylan. The low A bands identified in the lignin char produced at 400 °C indicate that crosslinking at low temperatures preferentially forms hexagonal or larger rings. Aromatic condensation increased until 500 °C, and remained stable up to 700 °C. The sharp drop in oxygen content as temperature is increased up to 500 °C and the formation of ether (C-O-C) groups indicates that oxygen is a primary reaction component for crosslinking and polycondensation. Despite the considerable increase in ring size for char produced at 700 °C compared to 500 °C, only very mild loss of oxygen is identified, suggesting that C-C bonds are forming with minimal oxygen mediation The increased broadness of the NMR peak and the Raman G band suggest that at these temperatures the increase in ring size occurs largely in a 3 dimensional manner rather than planar with contributions from non-hexagonal rings and out-of-plane distortion. By comparing the NMR dephasing data to the I(D)/I(G) ratio an approximate relation between this Raman data and cluster size has also been derived. [ABSTRACT FROM AUTHOR]

The aim of this research was to evaluate the potential for the stabilization of biomass-derived pyrolysis oils by using acid-catalyzed (Amberlyst 70) reactions with alcohol ( T=140-170 °C, P≈20 bar (1 bar=105 Pa)). The alcohol-stabilized oils were further upgraded by catalytic hydrotreatment ( T=400 °C, non-sulfided NiMo/Al2O3 catalyst) to give a biofuel. The concept was evaluated experimentally in terms of overall mass and energy balances and biofuel properties. The pyrolysis oil used in this study was obtained by fractional condensation of pyrolysis vapors and had a very low water content that favored the equilibrium conversion of the stabilization reactions. The energy efficiency was between 44 and 48 %. Preliminary results with acid-leached biomass showed that 43 % of levoglucosan in the pyrolysis oil was converted into methyl levulinate after the pyrolysis oil was purified. The proposed integrated concept of alcoholysis can be applied locally at the pyrolysis oil production site. [ABSTRACT FROM AUTHOR]

The objective of this work was to study the effect of torrefaction temperature on properties of patula pine (Pinus patula) wood that could be of interest for further thermochemical processing. Torrefaction temperature was varied from 200 to 300 °C for 30 minutes using a batch spoon type reactor. Raw and torrefied materials were characterized for proximate and ultimate analyses, thermogravimetry, and pyrolysis gas chromatography/mass spectrometry (Py-GC/MS). Results showed that torrefied pine has greater higher heating value and chemical exergy due to the reduction of O/C and H/C ratios. Compared with raw biomass, the material torrefied at 200 and 250 °C did not present significant changes in chemical composition and thermal behavior. Conversely, material torrefied at 300 °C did show important changes in both chemical composition and thermal behavior. Py-GC/MS results suggested that the main constituents of biomass, i.e., hemicellulose, cellulose and lignin, suffer a progressive thermal degradation with increase in torrefaction temperature. [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]

Oleaginous strains of Rhodococcus including R. jostii RHA1 have attracted considerable attention due to their ability to accumulate triacylglycerols (TAGs), robust growth properties and genetic tractability. In this study, a novel metabolic pathway was introduced into R. jostii by heterogenous expression of the well-characterized gene, lgk encoding levoglucosan kinase from Lipomyces starkeyi YZ-215. This enables the recombinant R. jostii RHA1 to produce TAGs from the anhydrous sugar, levoglucosan, which can be generated efficiently as the major molecule from the pyrolysis of cellulose. The recombinant R. jostii RHA1 could grow on levoglucosan as the sole carbon source, and the consumption rate of levoglucosan was determined. Furthermore, expression of one more copy of lgk increased the enzymatic activity of LGK in the recombinant. However, the growth performance of the recombinant bearing two copies of lgk on levoglucosan was not improved. Although expression of lgk in the recombinants was not repressed by the glucose present in the media, glucose in the sugar mixture still affected consumption of levoglucosan. Under nitrogen limiting conditions, lipid produced from levoglucosan by the recombinant bearing lgk was up to 43.54 % of the cell dry weight, which was comparable to the content of lipid accumulated from glucose. This work demonstrated the technical feasibility of producing lipid from levoglucosan, an anhydrosugar derived from the pyrolysis of lignocellulosic materials, by the genetically modified rhodococci strains. [ABSTRACT FROM AUTHOR]

Ozonation on the phenols present in pyrolytic aqueous phases attained from biomass thermochemical conversion was evaluated. During ozonation, the dark color of original samples was found to decrease as a function of ozonation time. The oxidation kinetics of phenols was quantified by a method based on the color changes of samples. The oxidation profiles showed different behaviors and in some cases the phenols presented a positive correlation with the relative R color parameter, except eugenol, syringol, and vanillin which were markedly different. Finally, the color changes observed seem to be associated with the changes in the overall content of phenols and with the change in the molecular weight of the heavy fractions that include lignin oligomers. [ABSTRACT FROM AUTHOR]

Highlights: [•] Pyrolysis of beech wood particles (0.3 and 14mm). [•] The yield of pyrolytic lignin decreased as particle size increased. [•] Two different pyrolysis regimes were confirmed between 0.3 and 14mm. [•] Secondary reactions and mass transfer limitations lead to more char. [Copyright &y& Elsevier]

Highlights: [•] Pyrolysis produces bio-oil for further upgrading to electricity, (transportation) fuels and chemicals. [•] Pyrolysis fits well into the existing fossil infrastructure (logistics and refining). [•] Several demonstration units (1–5ton/hours) considered. [•] Multilevel research from chemistry of the cell wall to optimization of whole factory. [•] Fermentation of pyrolytic sugars explores the interface between thermochemistry and biotechnology. [ABSTRACT FROM AUTHOR]

Abstract: This paper reports the production of lipids from non-hydrolyzed levoglucosan (LG) by oleaginous yeasts Rhodosporidium toruloides and Rhodotorula glutinis. Enzyme activity tests of LG kinases from both yeasts indicated that the phosphorylation pathway of LG to glucose-6-phosphate existed. The highest enzyme activity obtained for R. glutinis was 0.22U/mg of protein. The highest cell mass and lipid production by R. glutinis were 6.8 and 2.7g/L, respectively from pure LG, and 3.3 and 0.78g/L from a pyrolytic LG aqueous phase detoxified by ethyl acetate extraction, rotary evaporation and activated carbon. This corresponded to a lipid yield of 13.5wt.% for pure LG and only 3.9wt.% for LG in pyrolysis oil. [Copyright &y& Elsevier]

Abstract: The presence of very reactive C1–C4 molecules adversely affects the quality bio-oils produced from the pyrolysis of lignocellulosic materials. In this paper a scheme to produce lipids with Cryptococcus curvatus from the carboxylic acids in the pyrolytic aqueous phase collected in fractional condensers is proposed. The capacities of three oleaginous yeasts C. curvatus, Rhodotorula glutinis, Lipomyces starkeyi to ferment acetate, formate, hydroxylacat-aldehyde, phenol and acetol were investigated. While acetate could be a good carbon source for lipid production, formate provides additional energy and contributes to yeast growth and lipid production as auxiliary energy resource. Acetol could slightly support yeast growth, but it inhibits lipid accumulation. Hydroxyacetaldehyde and phenols showed high yeast growth and lipid accumulation inhibition. A pyrolytic aqueous phase with 20g/L acetate was fermented with C. curvatus, after neutralization and detoxification to produce 6.9g/L dry biomass and 2.2g/L lipid. [Copyright &y& Elsevier]

Abstract: This paper describes the use of Differential Scanning Calorimetry (DSC) to evaluate the impact of varying mix ratios of bio-oil (pyrolysis oil) and bio-diesel on the oxidation stability and on some cold flow properties of resulting blends. The bio-oils employed were produced from the semi-continuous Auger pyrolysis of pine pellets and the batch pyrolysis of pine chips. The bio-diesel studied was obtained from poultry fat. The conditions used to prepare the bio-oil/bio-diesel blends as well as some of the fuel properties of these blends are reported. The experimental results suggest that the addition of bio-oil improves the oxidation stability of the resulting blends and modifies the crystallization behavior of unsaturated compounds. Upon the addition of bio-oil an increase in the oxidation onset temperature, as determined by DSC, was observed. The increase in bio-diesel oxidation stability is likely to be due to the presence of hindered phenols abundant in bio-oils. A relatively small reduction in DSC characteristic temperatures which are associated with cold flow properties was also observed but can likely be explained by a dilution effect. [Copyright &y& Elsevier]

Abstract: This paper describes the production and fuel properties of fast pyrolysis oil/bio-diesel blends. The bio-oils used in this study were produced from the fast pyrolysis of woody biomasses, oil mallee and pine. The bio-diesel employed was derived from canola vegetable oil. The conditions used to prepare the bio-oil/bio-diesel blends, as well as some of the fuel properties of the resulting bio-diesel rich phase, are reported. The experimental results show that the solubility of fast pyrolysis oils in bio-diesel is not as high as was previously reported for decanted oils obtained by Auger pyrolysis. The carboxylic acids, mono-phenols, furans and lignin derived oligomers were the compounds most soluble in bio-diesel, while the sugars, on the other hand, showed poor solubility. Although the presence of phenols enhances the oxidation stability of the bio-diesel rich phases, other fuel properties deteriorate. For example, the content of solid residues increased primarily because of the solubilisation of lignin derived oligomers, which were quantified by UV-fluorescence. Concentrations as high as 3.5mass % of these compounds were observed in the bio-diesel rich phase. The solubility of bio-oil in bio-diesel was enhanced by using ethyl acetate/bio-diesel blends. Some fuel properties of the bio-diesel rich phase, after the removal of ethyl acetate, are reported. [Copyright &y& Elsevier]

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]

Catalytic hydrotreatment followed by products isomerization is an effective technology to convert vegetable oil to a green fuel composed of straight and branched chain aliphatic hydrocarbons. The content of aromatics in this fuel is very low. In this paper we study the co-hydrotreatment of vegetable oil and tires oil in the presence of a CoMo/Al 2 O 3 catalyst as a way of utilizing existing infrastructure created for vegetable oil processing for tire oil up-grading in order to obtain fuel cuts with aromatics. Hydrotreatment studies with different vegetable oil/tires oil blend ratios were conducted. The yield and composition of the resulting hydrotreated oils are reported. Aliphatic hydrocarbons ranging from C7 to C20 derived from vegetable oils and aromatics from C6 to C16 derived from the tire oil were identified as products. The resulting oils were then successfully distilled into naphtha, kerosene, diesel and gas oil cuts. The yield, chemical composition and the fuel properties of the transportation fuel cuts obtained are reported and compared with commercial petro derived fuels. [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]

Abstract: This study aims to investigate the effects of biomass particle size (0.18–5.6mm) on the yield and composition of bio-oil from the pyrolysis of Australian oil mallee woody biomass in a fluidised-bed reactor at 500°C. The yield of bio-oil decreased as the average biomass particle size was increased from 0.3 to about 1.5mm. Further increases in biomass particle size did not result in any further decreases in the bio-oil yield. These results are mainly due to the impact of particle size in the production of lignin-derived compounds. Possible inter-particle interactions between bio-oil vapour and char particles or homogeneous reactions in vapour phases were not responsible for the decreases in the bio-oil yield. The bio-oil samples were characterised with thermogravimetric analysis, UV-fluorescence spectroscopy, Karl–Fischer titration as well as precipitation in cold water. It was found that the yields of light bio-oil fractions increased and those of heavy bio-oil fractions decreased with increasing biomass particle size. The formation of pyrolytic water at low temperatures (<500°C) is not greatly affected by temperature or particle size. It is believed that decreased heating rates experienced by large particles are a major factor responsible for the lower bio-oil yields from large particles and for the changes in the overall composition of resulting oils. Changes in biomass cell structure during grinding may also influence the yield and composition of bio-oil. [Copyright &y& Elsevier]

Abstract Anaerobic digestion (AD) is an important technology to produce biogas from dairy manure. Although the AD of dairy manure results in the harnessing of the energy contained in manure, most of the nutrients (phosphorous and nitrogen) remain in the liquid effluent, representing an important source of pollution. Additionally, the biogas produced contains H 2 S and CO 2 , limiting its practical use as fuel. In this paper, we report the production and use of a carbonaceous adsorbent from AD fibers for the removal of hydrogen sulfide (H 2 S) from biogas and phosphate (PO 4 3−) from aqueous liquid effluents. The adsorbents studied were produced via slow pyrolysis between 350 and 800 °C followed by CO 2 activation. The elemental and proximate analyses, surface area and pore size distribution of each of the adsorbents studied are reported. Their adsorption capacities were assessed using H 2 S breakthrough and PO 4 3− batch equilibrium tests. The sorption capacity varied between 21.9 and 51.2 mg g−1 for H 2 S and between 4.9 mg g−1 and 37.4 mg g−1 for PO 4 3−. Commercially available activated carbon studied adsorbed 23.1 mg g−1 H 2 S and 15.7 mg g−1 PO 4 3−. The results show that the retention of H 2 S and PO 4 3− compounds were governed by the ash content, surface area and pH. Adsorption mechanisms for H 2 S and PO 4 3− sorption are proposed. Graphical abstract Image 1 Highlights • Anaerobically digested fiber is suitable for producing activated char. • The activated char produced demonstrated high capacity to adsorb H 2 S and PO 4 3−. • Production temperature has a major influence on the capacity of the resulting biochar towards H 2 S and PO 4 3−. • The content and composition of ash are critical for H 2 S and PO 4 3− removal. • Micropores volume is an important factor in H 2 S retention. [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]

Anaerobically digested fibrous solid (AD fiber) is an abundant material that offers potential to produce value-added products such as biochar. The objective of this paper is to better understand how thermochemical processing conditions affect the capacity of biochars derived from AD fiber to adsorb H 2 S from biogas. AD fiber was pyrolyzed in an electric tube reactor at temperatures up to 600 °C and 60 min. The chars were employed for H 2 S scrubbing tests from a synthetic biogas. Results showed that the chars’ capacity for H 2 S removal is comparable to that of activated carbon. An additional step consisting of impregnation of the chars with Na 2 CO 3 resulted in an improved capacity for H 2 S removal. To study the effect of ash, the AD fiber was also subjected to an alternative thermal treatment, hot water extraction (HWE), at 200 °C for 60 min. The resulting HWE material showed no removal of H 2 S from biogas, indicating that the ash and the environment employed for the thermal treatment of AD fiber play an important role in the char’s performance for H 2 S removal. Results also suggest that a portion of the S in the charcoal after the H 2 S sorption process exists as free or adsorbed S (i.e., not chemically bonded to the charcoal). [ABSTRACT FROM AUTHOR]

Thin films (~115 μm thick) of milled wood lignin from hybrid poplar and acid-washed hybrid poplar were pyrolyzed at 500 °C and ~55 °C/s at five pressures (4, 250, 500, 750, and 1000 mbar) to determine the impact of secondary liquid intermediate reactions on the product distribution. For both milled wood lignin extracted from poplar and acid-washed hybrid poplar wood, pressure had a significant effect on the product distribution for thin film pyrolysis between 4 and 1000 mbar. For lignin, lowering the pressure from 1000 mbar to 4 mbar reduced the char yield from 36 to 23% and enhanced production of large cluster pyrolytic lignin. However, the pressure did not dramatically impact the gas yield (CO2, CO, methane, H2, ethane, propane, and butane), nor did it significantly impact the release of monomeric phenolic compounds. ICR-MS shows limited changes in the composition of lignin oligomers. The increase in the production of large lignin oligomers observed by UV fluorescence and the reduction of char yield with vacuum confirm the importance of oligomeric combination reactions to form large polyaromatic structures in the liquid intermediate. For hybrid poplar, lowering the pressure from 1000 mbar to 4 mbar decreased the char yield from 19 to 7% and enhanced production of heavy sugars (cellobiosan and cellotriosan). ICR-MS results clearly show the importance of dehydration reactions in the liquid intermediate. Lowering the pressure also enhanced production of CO, CO2, and methane due to heterogeneous catalysis by residual alkali and alkaline earth metals in the solid wood matrix. However, it also decreased production of levoglucosan from 10 to 6.1 wt %. The yields of levoglucosan and cellobiosan obtained for hybrid poplar were higher and lower, respectively, compared with those expected if the pyrolysis products were the result of the additive contribution of hybrid poplar constituents. This result could be explained by the tendency of lignin liquid intermediate to bubble vigorously, contributing in this way to the removal of cellulose oligomers from the liquid intermediate. [ABSTRACT FROM AUTHOR]

Recent results obtained by Raman spectroscopy as well as Transmission Electron Microscopy highlight the importance of irregular structures within amorphous chars. Results from DFT simulations, reported here, suggest that irregular ring systems contribute strongly to the asymmetry often observed in the aromatic peak near 140 ppm. By combining a recently developed cross-polarization pulse sequence designed for quantitative analysis of even low hydrogen containing materials with long range dipolar dephasing, we examine the structure of a thermoseries of chars produced from cellulose. These results demonstrate the consistent growth of cluster size with pyrolysis temperature, and examine for the first time the distribution of ether groups and defects within the cluster. These results highlight the contribution of defects to the structure and show localization of ether groups toward the periphery of the clusters. Only minor ether contributions were associated carbon sites most distant from hydrogens, suggesting that cluster growth occurs largely by reaction at these sites. The prevalence of oxygenated and defect carbon sites throughout the aromatic clusters highlights the need for additional characterization of these materials as these sites are likely to offer substantially different reactivity and adsorption behavior compared to regular aromatic structures. [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]

Pyrolysis of thin films of cellulose was performed at five pressures from 4 mbar (vacuum) to 1 bar at 500 °C in a modified pyroprobe captive sample reactor designed to minimize gas-phase secondary reactions. Known molecule products were identified and quantified by gas chromatography (GC), GC/mass spectrometry (MS), and high-performance liquid chromatography, and yields were calculated. Vacuum allowed the evaporation of cellobiosan and promoted the release of heavy oligosaccharides by thermal ejection (cellotriosan, etc.), reducing in this way the residence time of the oligomeric products in the liquid intermediate and, consequently, their secondary reactions. The char yield increased from 3.6 to 8.3% in the range of pressures studied. The unknown heavy fractions in the oil were studied in more detail by high-resolution mass spectrometry using positive-ion electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry. The results illustrated a dominant dehydration reaction pathway in the liquid intermediate to form distinct parent molecules from which fragmentation reactions occur. Notable reactions were decarboxylation, loss of glycoaldehyde, 5-(hydroxymethyl)furfural, and 1,4:3,6-dianhydro-α-d-glucopyranose, and gain of hydrogen, methanol, and water. Furthermore, as the pressure increased, cross-linking and polyaromatic ring formation in the liquid intermediate were enhanced. A new cellulose pyrolysis reaction scheme stressing the secondary reactions in the liquid intermediate was proposed to reflect the results of this study. [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]

The aim of this work was to improve sugarcane bagasse thermochemical conversion to pyrolytic sugars production, particularly to levoglucosan. The experiments were carried out evaluating the effect of acid washing with HNO 3 (0.1 wt.%) followed by H 2 SO 4 addition (0.1, 0.2 and 0.3 wt.%) at pyrolysis temperatures of 350, 400, 450, 500, 550 and 600 °C was studied by Py-GC/MS. The experimental results showed that HNO 3 washing, followed by H 2 SO 4 concentration of 0.2 wt.% at 350 °C resulted in an increase in levoglucosan yield between 5 and 7 times the yield obtained when the raw bagasse was processed. Thus, these results are very attractive to improve pyrolytic sugars production in sugarcane bagasse by previously acid treatment to pyrolysis technology. [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]

The complex heterogeneous nature of chars has confounded the complete analysis of the Raman spectra of these materials. The additional shoulders observed on the defect (D)-band and high intensity valley between the D and graphitic (G)-bands represent the primary regions of uncertainty. In this paper the effects of various vacancy and substitution defects in a coronene parent molecule have been systematically analyzed using density functional theory (DFT). The impacts of these defects are best understood in terms of a reduced symmetry as compared to a “parent” coronene molecule. Based on simulation results, a total of ten potential bands have been assigned between 1000 cm −1 and 1800 cm −1 . These bands have been used to deconvolute a thermoseries of cellulose chars produced by pyrolysis at 300–700 °C. The shoulder observed in chars near 1200 cm −1 has been assigned to the symmetric breathing mode of various small polyaromatic hydrocarbons (PAH) as well as rings containing seven or more carbons. Intensity between 1400 cm −1 and 1550 cm −1 results from a range of coupled vibrational modes from various defect structures. The deconvolution of cellulose derived chars shows consistent growth of PAH clusters, loss of oxygen, and development of non-hexoganal ring systems as pyrolysis temperature increased. [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]

This paper reports the effects of pyrolysis temperature on biochar to oxidation by air. Eighteen biochars were produced from the pyrolysis of Douglas fir wood (DFW), Douglas fir bark (DFB), and hybrid poplar wood (HP) at six temperatures (623, 673, 723, 773, 823 and 873 K) in a lab scale spoon reactor. The oxidation step for all biochars produced was conducted at 523 K in the presence of air in a spoon reactor. The elemental and proximate analyses of all the oxidized and un-oxidized chars suggest that the carbonaceous materials produced at low temperature are more susceptible to oxidation than those produced at high temperature. A number of surface properties of resultant biochars were examined to better understand how pyrolysis temperatures and feedstock sources relate to the development of surface characteristics. The removal of volatiles during the pyrolysis step resulted in the gradual creation of microporosity detectable by CO 2 adsorption but which was difficult to detect with N 2 adsorption, suggesting that the chars contain micropores mostly less than 1 nm in entrance dimension. In some cases, the surface area decreased after being oxidized likely due to the blockage of micropores by oxygen-containing functional groups. The surface composition determined by XPS and Boehm titration confirms that greater quantities of carbonyl and carboxyl groups are formed on biochars produced at low temperature. The formation of these oxygenated functional groups contributes to add negative charges on the surface and consequently the pH at the point of zero charge increases for un-oxidized biochars. [ABSTRACT FROM AUTHOR]

The use of ozone to increase the cation exchange capacity (CEC) of two chars produced from pyrolysis of Douglas fir ( Pseudotsuga menziessii ) and a control bituminous coal activated carbon (AC) is reported. Chars were produced from the wood fraction of Douglas fir (DFWC) and the bark (DFBC) at 500 °C using an auger driven reactor with a nitrogen sweep gas under mild vacuum. Five ozone treatment times, ranging from 5 min to 60 min, were investigated. The initial properties of each char were found to differ significantly from the other samples in terms of surface area, proximate composition, and elemental composition. DFWC did not show significant mass loss or temperature variation during ozone treatment; however, after 1 h of oxidation both DFBC and AC samples resulted in 20% and 30% mass loss, respectively, and reactor temperatures in excess of 60 °C. Analysis of the pore size distribution of each treatment shows that ozone treatment did not significantly affect small micropores after 30 min of treatment for any material, but did reduce the apparent surface area of mesopores. Increases in carboxylic groups were identified with ozone treatment and found to correlate strongly with changes in measured CEC. The formation of lactone was found to correlate positively with reactor temperature during oxidation. These results indicate that the properties of chars, including surface area, pore structure, and chemical composition, as well as reactor conditions strongly affect the ozone oxidation of chars. [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]

The formation of liquid intermediates and the distribution of products were studied under slow and fast pyrolysis conditions. Results indicate that monomers are formed from lignin oligomeric products during secondary reactions, rather than directly from the native lignin. Lignin from Douglas-fir (Pseudotsuga menziesii) wood was extracted using the milled wood enzyme lignin isolation method. Slow pyrolysis using a microscope with hot-stage captured the liquid formation (>150 °C), shrinking, swelling (foaming), and evaporation behavior of lignin intermediates. The activation energy (E a) for 5–80% conversions was 213 kJ mol−1, and the pre-exponential factor (log A) was 24.34. Fast pyrolysis tests in a wire mesh reactor were conducted (300–650 °C). The formation of the liquid intermediate was visualized with a fast speed camera (250 Hz), showing the existence of three well defined steps: formation of lignin liquid intermediates, foaming and liquid intermediate swelling, and evaporation and droplet shrinking. GC/MS and UV-Fluorescence of the mesh reactor condensate revealed lignin oligomer formation but no mono-phenols were seen. An increase in pyrolytic lignin yield was observed as temperature increased. The molar mass determined by ESI-MS was not affected by pyrolysis temperature. SEM of the char showed a smooth surface with holes, evidence of a liquid intermediate with foaming; bursting from these foams could be responsible for the removal of lignin oligomers. Py-GC/MS studies showed the highest yield of guaiacol compounds at 450–550 °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: Washington State University is located in a fertile region known as the Palouse. As one of the highest wheat-producing regions in the world, there are 458,553 tonnes of field residue available after each harvest. The close proximity of this untapped biomass resource is an outstanding opportunity to generate heat, hydrogen, and power for the university campus. The novel concept proposed utilizes a stepwise thermochemical conversion concept (pyrolysis–gasification) as the first step to produce pyrolytic char, vapor and syngas. The resulting syngas is then converted into methane via the methanation reaction prior to feeding it into a molten-carbonate fuel cell with a reformer for electricity production. The hydrogen produced can be used for fueling transit and maintenance vehicles, and for producing fertilizer. The byproduct heat is used to warm nearby research greenhouses and the electricity to power an expanding campus. Excess pyrolytic vapor can offset the fueling cost and emissions of the university steam plant and ash can be commercialized as a soil amendment. This manuscript is based on a project submitted by the students to the 2012 Hydrogen Student Design Contest. [Copyright &y& Elsevier]

Inthis work we report on the preparation, characterization, andproperties of a thermally treated lignin-derived, phenolic-rich fraction(PRF) of wood pyrolysis bio-oil obtained by ethyl acetate extraction.The PRF was characterized for viscoelastic and rheological behaviorusing dynamic mechanical analysis (DMA) and cone and plate rheology.A unique thermoplastic behavior was evidenced. Heat-treated PRFs acquirehigh modulus but show low temperatures of thermal flow which can besystematically manipulated through the thermal pretreatment. Lossof volatiles, changes in molecular weight, and glass transition temperature(Tg) were investigated using thermogravimetricanalysis (TGA), mass spectrometry (MS), and differential scanningcalorimetry (DSC), respectively. Underlying mechanisms for the thermaland rheological behavior are discussed with regard to interactionsbetween pyrolytic lignin nanoparticles present in the system and therole of volatile materials on determining the properties of the materialresembling in several aspects to colloidal suspension systems. Lowthermal flow temperatures and reversible thermal effects can be attributedto association of pyrolytic lignin particles due to intermolecularinteractions that are easily ruptured at higher temperatures. Thethermoplastic behavior of PRF and its low Tgis of particular interest, as it gives opportunities for applicationof this fraction in several melt processing and adhesive technologies. [ABSTRACT FROM AUTHOR]

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: The effect of sulfuric acid concentration on the yield and composition of bio-oils obtained from the auger and fluidized bed pyrolysis of Douglas Fir at 500°C have been investigated as a mean to enhance the production of fermentable sugars. The concentration of sulfuric acid in the feedstock was varied between 0 and 0.6mass%. The overall yield of pyrolysis products (gas, bio-oil and char) was comparable for both reactors. The presence of sulfuric acid decreases bio-oil yield and increases water and char yields. The yield of pyrolytic water produced in the auger reactor was higher due to the lower heating rates achieved which favor dehydration reactions. Maximum yields of levoglucosan and fermentable sugars were obtained at concentrations of sulfuric acid of 0.3mass% in the auger reactor and 0.05mass% in the fluidized bed reactor. Dehydration reactions responsible for water and cross linked sugars formation, as observed by the increase in the band at 1654cm−1 fitted in the FTIR, were enhanced as sulfuric acid concentration increases. The dehydration of cellulose in the presence of sulfuric acid also causes a reduction in the yield of acetic acid and acetol. The yields of some lignin derived compounds (lignin oligomers and guaiacols) also decreased substantially when sulfuric acid was added. Potential mechanisms responsible for the phenomena observed are discussed. [Copyright &y& Elsevier]

Abstract: This paper investigates the effect of thermal pretreatment temperatures between 200 and 370°C on the yield and composition of products (bio-charm gasm water and organics) obtained when Douglas-fir wood was subsequently pyrolyzed in an auger reactor at 500°C. The yield of products was reported for the pretreatment and pyrolysis steps separately, and for the two steps added. The maximum yield of bio-oils achieved without pretreatment was close to 59mass%. A decrease in total liquid yield was observed when the biomass was pretreated at 300°C. At higher temperatures, the yields of Douglas-fir primary degradation products (lignin oligomers, anhydrosugars and alkylated and methoxylated phenols) decreased. The overall water yield increased gradually to 14mass% at a pretreatment temperature of 290°C. The yield of lignin oligomers also decreased as the pretreatment temperature increased. A drastic reduction in the yield of methoxylated phenols derived from guaiacyl (G) was observed when the biomass was pretreated at temperatures over 300°C. This drastic reduction in the yield of methoxylated lignin derivatives can be explained by the formation of liquid intermediates that facilitate the formation of ionic species, enhancing dehydration reactions leading to the production of o-quinone methide intermediates critical for bio-char formation. [Copyright &y& Elsevier]

Abstract: This paper investigates the effect of sulfuric acid (H2SO4) concentration, as an additive to enhance the production of anhydrosugars via pyrolysis of Douglas-fir, on the yield and composition of the lignin derived oligomers. Pyrolysis tests at 500°C were conducted in auger and fluidized bed reactors. For both reactors the yield of lignin derived oligomers decreased as H2SO4 was added. Several analytical techniques (UV-fluorescence, TGA, ESI-MS, FTIR, solid state 13C NMR and Pyrolysis-GC/MS) were used to characterize the lignin derived oligomers collected. Four peaks were observed in the UV-fluorescence spectra. The addition of H2SO4 reduces the yield of all the peaks. DTG curves also show the presence of several peaks. The addition of H2SO4 decreased the yield of all the peaks but its effect was more pronounced on peaks at 320 and 400°C. Electrospray ionization-mass spectrometry studies did not show any major change on the molecular weight of the lignin oligomers ionized products obtained as a function of H2SO4 concentration. Solid state NMR results indicate that the methoxyl groups decreased and the carbonyl increased gradually as sulfuric acid concentration increases. The Py-GC/MS confirmed the phenolic compounds with methoxyl substitutions were substantially reduced as the acid concentration increased. The experimental results obtained suggest the presence of H2SO4 enhances the polycondensation of methoxyl substituted aromatic rings. [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]