Search

Sugar maple (Acer saccharum) wood chips were pretreated with aqueous sodium hydroxide, sodium borohydride, and hydrogen peroxide pretreatments, and the characterization (i.e., amount, molar masses, and molar mass distributions) of the lignin dissolved during the pretreatments was performed. Of the applied pretreatments, especially borohydride pretreatments were efficient in dissolving lignin from this feedstock, as 20% to 28% of the dissolved organics were found to consist of dissolved lignin, contributing to 3.4% to 9.0% of the initial wood lignin. Corresponding values for 2.5% and 5.0% alkaline peroxide pretreatments were from 5.9% to 9.2% dissolved lignin of the total dissolved organics and from 1.1% to 3.2% of the initial wood lignin. Additionally, determined molar masses and molar mass distributions indicated that borohydride pretreatments generally led to the formation of smaller-molar-mass lignin fragments when compared to reference pretreatments and to pretreatments conducted with alkaline peroxide process, indicating more efficient lignin degradation caused by borohydride addition. For example, Mn and Mw values of the analyzed reference effluents were 54%-62% and 66%-71% higher when compared to the corresponding borohydride effluents, respectively. [ABSTRACT FROM AUTHOR]

The objective of this work was to determine the effect of sodium methyl mercaptide (SMM) on the yield of the packaging-grade kraft pulp. Based on our experience with bleachable grade kraft pulping using SMM, only a co-addition of 4.38% SMM with white liquor was studied. The cooking temperature and H-factor were adjusted to reach the target kappa number. The experimental results showed about a 2.7% (on O.D. (oven dry) wood basis) increase in the pulp yield after the co-addition of 4.38% SMM (on O.D. wood basis). The use of 4.38% SMM allowed lowering of the severity of the following process variables: the white liquor effective alkali charge (EA, on O.D. wood basis) by 2.4%, the cooking temperature from 165 °C to 157 0C, and the H-factor from 535 to 295. For 98 kappa pulp, the increase in pulp yield was mostly due to the increased retention of xylan (1.63%, on wood basis) and lignin (1.71%). The retention of galactoglucomannan was negligible (0.26%). There was a minor loss of cellulose (0.70%). The increase in the pulp yield in the presence of SMM can be explained by two non-exclusive mechanisms: stabilization of carbohydrate-reducing end groups during impregnation, and faster delignification during the bulk cooking phase. Based on the experimental data, we presently do not know which of the two mechanisms for increasing the pulp yield is dominating. [ABSTRACT FROM AUTHOR]

Using a Berty-type CSTR reactor, Ji (2007. Kinetics and mechanism of oxygen delignification, Ph.D. thesis. The University of Maine) obtained oxygen delignification kinetics first order in lignin when neglecting the higher initial delignification phase. In the present study the same Berty/CSTR reactor with an improved temperature control was used to determine the oxygen delignification kinetics of Southern Pine kraft pulp, with the kinetics now corrected for lignin removed by oxygen-free alkaline leaching. This removes the initial high delignification rate peak so that the kinetics over the entire lignin range can be modelled as first order in "reactive" lignin, which is lignin corrected for a small amount of unreactive lignin. It suggests that softwood pulp oxygen delignification consists of two contributions; phenolic delignification and alkaline leaching. The initial alkaline leaching phase is mathematically described by semi-infinite alkaline diffusion of dissolved lignin trapped in the cell wall after pulp washing. For phenolic delignification, the reaction orders in alkali concentration and oxygen of the power law delignification equation are 0.3 and 0.44 respectively, while the activation energy is 63 kJ/mol. Taking into account the unreactive HexA, the small amount of unreactive lignin, and the lignin removed by alkaline leaching, the kappa number is well predicted by the new delignification kinetics. [ABSTRACT FROM AUTHOR]

The objective of this work was to determine the effect of sodium methyl mercaptide (SMM) as an additive on the minimization of carbohydrate peeling reactions in Rock/Hard Maple (Acer saccharum) chips during kraft pulping. Two methods were evaluated for SMM addition to the pulping process: 1) pre-treatment before pulping and 2) co-addition with white liquor. The experimental results showed about 2.5% (on wood basis) increase in the kraft pulp yield after pre-treatment with 4.38% SMM (on wood basis) or the co-addition of the same amount of SMM with white liquor. The use of 4.38% SMM allowed a decrease in the white liquor effective alkali charge of 3% (on wood basis) to produce the target 14–15 kappa pulp. The 4.38% SMM charge was determined to be the optimum for both pre-treatment and co-addition. The increase in kraft pulp yield was mostly due to increased retention of cellulose (about 0.8% on wood) and xylan (about 1.8% on wood). The retention of glucomannan was insignificant in all cases. Based on the increase in intrinsic viscosity, it is concluded that the increased cellulose yield with SMM addition is caused by both reduced primary peeling and faster delignification rate (less alkaline hydrolysis followed by secondary peeling). The increased xylan retention is due to the lower effective alkali concentration during kraft pulping with SMM addition. [ABSTRACT FROM AUTHOR]

For recovering value-added wood-based organic material prior to delignification, sodium borohydride (NaBH4) and hydrogen peroxide (H2O2) pretreatments under alkaline conditions were performed before soda pulping of sugar maple (Acer saccharum) chips with sodium hydroxide (NaOH). In this investigation, it was determined whether the pulp yield could be increased by partly stabilizing the hemicelluloses by these pretreatments, and simultaneously obtains lower pulp kappa numbers. The results indicated that when aiming to the same kappa numbers (i.e., kappa numbers 14.3-20.5), roughly 3% higher pulp yield could be achieved if the chips were pretreated with alkaline 0.5% NaBH4 solutions, compared to those produced without such pretreatment or pretreated only with NaOH (i.e., without NaBH4). In contrast, pretreatments conducted with alkaline 2.5% H2O2 did clearly lower pulp yields at the same kappa number range (14.0-22.7) when compared to the reference cooks conducted with NaOH pretreated materials. However, an increase in the H2O2 charge of the pretreatment from 2.5% to 5.0% had a clearly beneficial effect, as the pulp yield and kappa numbers after pulping of 5.0% H2O2 pretreated pulps were comparable to the reference cooks. [ABSTRACT FROM AUTHOR]

Sugarcane straw (SCS) lignin is extracted by SO 2 -Alcohol-Water (SAW) fractionation (155 °C, 1 h) using methanol, ethanol or isopropanol as pulping solvent (SO 2 /Alcohol/Water = 12/44/44 wt%). The SAW fractionation removes 90–95% lignin from SCS of which only 30–45% is isolated as precipitated lignin after solvent evaporation. The precipitated and pulp residual lignin (5–10%) are analyzed for their degree of sulfonation (S/C9) while precipitated lignin is further analyzed in terms of molecular weight distribution (MWD) and alkoxylation reactions. Similar S/C9 values for methanol, ethanol and isopropanol lignin show that the degree of sulfonation is independent of fractionation solvent. However, the sulfonated lignin is comparatively less soluble in the methanol-based liquor compared to the corresponding lignins in the ethanol- and isopropanol-based liquors. The mass average molecular weight, M w , is highest for isopropanol lignin (∼3800) while the numbers for methanol and ethanol lignins are comparatively smaller but nearly equal in magnitude (∼3000). Alkoxyl groups and nuclear magnetic resonance (NMR) analyses are performed to interpret the differences in lignin M w and alkoxylation reactions. Different ether and ester type linkages are identified in NMR spectra confirming lignin alkoxylation. Lignin carbohydrate complexes (LCC) are also found in NMR spectra confirming that some of the detected carbohydrates are covalently bound to lignin. [ABSTRACT FROM AUTHOR]

Wheat straw was pretreated at 150 °C for 100 min at a liquor-to-straw ratio of 6 L/kg (oven dry basis) straw using aqueous formic acid (FA) concentrations ranging from 0 to 15 g/L. The results showed excellent sugar and lignin mass balances for pretreatment, and precipitated lignin in the hydrolysate obtained at 15 g/L of FA decreased to 0.31 g/100 g straw compared to autohydrolysis (no FA) of 0.94 g/100 g straw. The average molecular weight of precipitated lignin decreased from 1970 g/mole for autohydrolysis to 710 g/mole at 15 g/L of FA. The monomeric sugar yield during pretreatment improved from 3.83 g/100 g for autohydrolysis to 23.5 g/100 g at 15 g/L FA. [ABSTRACT FROM AUTHOR]

SO2–ethanol–water (SEW) and SO2–isopropanol–water (SPW) spent liquors are obtained by fractionating sugarcane straw. The SEW and SPW liquors contain significant amounts of chemically bound xylose as ethyl xylosides (EX) and isopropyl xylosides (PX) respectively. The liquors are subjected to a constant temperature heat treatment to hydrolyze the alkyl xylosides to allow full recovery of xylose and alcohol. Complete hydrolysis of EX and PX is achieved at 121 °C in 70 and 30 min, respectively. The first-order kinetics of EX and PX hydrolysis are determined at temperatures from 100 to 121 °C. At full hydrolysis of the alkyl xylosides, the quantity of alcohol produced is greater than stoichiometric. Other sources of covalently bound alcohols in the spent liquors are identified to explain the excess alcohol produced. [ABSTRACT FROM AUTHOR]

High solvent recovery and monomeric sugar yield are essential for a viable biochemical conversion technology. The SO2-ethanol-water (SEW) or AVAP® process has great potential to produce easily fermentable pulp fibers and sugars dissolved in the spent liquor stream. The SEW fractionation process is evaluated for delignification, xylan removal and potential reactions between ethanol and sugarcane straw (SCS) carbohydrates. α-ethyl-xyloside (aEX) and β-ethyl-xyloside (bEX) formed by reaction of ethanol with xylose are quantified. The fractionation experiments are carried out at 135°C, 145°C, and 155°C for 20-120 min at fixed liquor composition (SO2/EtOH/H2O = 12:44:44, w/w) and liquor to feedstock ratio (4 l kg-1). The results are interpreted in terms of combined severity factor (CSF). Maximum ethyl xylosides (EX, or sum of aEX and bEX) and monomeric xylose concentrations are observed at CSF of 2.4 ± 0.1. The maximum amount of EX in spent liquor accounts for nearly 1.4% of EtOH (feedstock basis). The implications for downstream recovery of EtOH and sugars from the spent liquor are discussed. [ABSTRACT FROM AUTHOR]

Kinetics of SO 2 –ethanol–water (AVAP®) fractionation was determined for sugarcane (SC) straw in terms of pulp composition (non-carbohydrate components, cellulose, hemicelluloses) and properties (kappa number, pulp intrinsic viscosity in CED and cellulose degree of polymerization). Effect of temperature (135–165 °C) and time (18–118 min) was studied at fixed liquor composition (SO 2 /ethanol/water = 12:22.5:65.5, w/w) and a liquor-to-solid ratio (4 L kg −1 ). Interpretation is given in terms of major fractionation reactions, removal of non-carbohydrate components and xylan, as well as acid hydrolysis of cellulose, and is compared to other lignocellulosic substrates (beech, spruce and wheat straw). Overall, SO 2 –ethanol–water process efficiently fractionates SC straw by separating cellulose from both non-carbohydrate components and xylan while reducing cellulose DP. [ABSTRACT FROM AUTHOR]

This study deals with a biorefinery concept based on larch wood. Wood chips of Siberian larch (Larix sibirica Lebed.) were treated with water before pulping at the optimal pre-extraction (PE) condition of 150 °C and 90 minutes. Through PE, about 12.4% of the wood mass is dissolved, mainly from the arabinogalactan hemicellulose component. Fermentation of the hemicellulose-rich larch extract with Bacillus coagulans resulted in consumption of all C6 and C5 sugars and produced lactic acid in high yield. PE before pulping resulted in lower (4 to 5%) pulp yield than for control kraft pulps. However, the pulp yield loss may be reduced by addition of polysulfide (PS) and anthraquinone (AQ). The present study focuses on the effect of the degree of washing of the extracted chips and that of the PS charge in PSAQ pulping on the final properties of the pulp. Three different levels of washing and three different PS charges were tested. The characteristics of the extract, wash water, pulp, and black liquor samples were determined. The amount of sugars in the combined stream of collected extract and wash water obtained by mild washing was 10.2% on o.d. wood. [ABSTRACT FROM AUTHOR]

Formic acid is demonstrated as a hydrogen source in a solid reaction system by first stabilizing the acid as a calcium salt which then decomposes at temperatures of relevance in pyrolytic reactions. High yields of deoxygenated hydrocarbons are produced by thermal decomposition of formic and levulinic acid mixtures where the optimum feed stoichiometry is consistent with that of cellulose hydrolysis and dehydration. The method promises a high-yield, robust, low-pressure, non-catalytic route for converting biomass hydrolyzates to hydrocarbon mixtures which are similar to petroleum crude oils. [ABSTRACT FROM AUTHOR]

Quantitative determination of lignin in SO2-ethanol-water (SEW) pulps and spent liquors is described. The methods developed for conventional sulfite pulping are successfully applied to the SEW process. Linear correlations between Klason/total lignin content and kappa number are found over a wide pulp yield range for spruce, beech, and wheat straw. Lignin content of the spruce spent SEW liquors is determined using either hydrogen peroxide to remove SO2 and dilution by 3% sulfuric acid or simply by dilution with 0.1M sodium hydroxide. The recommended wavelength is 280 nm. The experimentally found values for the extinction coefficient of dissolved lignin in 3% sulfuric acid and in 0.1M NaOH are 19 and 23 L/(g·cm), respectively. The interference of furanic compounds is eliminated by reduction with sodium borohydride. [ABSTRACT FROM AUTHOR]

A simplified method for sequentially dissolving and fractionating ball milled hard wood polymers in high yield is presented. The complete dissolution of the whole ball milled wood, and the fractions recovered from it by applying the sequential fractionation, was accomplished in lithium chloride/dimethylacetamide solvent system enabling size exclusion chromatography studies. The chromatography applied a four detector system; an Ultraviolet-Visible spectroscopy-, Intrinsic Viscosity-Differential Pressure-, Right Angle Laser Light Scattering- and Refractive Index detectors, a combination hereby proposed to enable interpretation of the complex elution profiles with emphasis on chemical interactions. Indirect evidence of the presence of lignin carbohydrate complexes in hardwoods is provided. It is also proposed that cellulose is severely degraded from a degree of polymerization of 10,000 in wood, down to a value of approximately 400 by either the applied ball milling condition or in subsequent solubilization steps. [ABSTRACT FROM AUTHOR]

Abstract: In order to utilize hemicelluloses from biomass as a feedstock for production of higher value added products such as biofuels and bio-based chemicals, it is essential to assess the chemical composition of the liquid phase and molecular weight distribution of isolated carbohydrates. The association of hemicelluloses with lignin also plays an important role for utilization of isolated hemicelluloses. In the present study carbohydrates were first extracted from a mixture of southern hardwoods by autohydrolysis at different temperatures for 100min, and then precipitated after mixing with four volumes of ethanol. Depending on the temperature, all (100% at 130°C) or a small part (5% at 170°C) of the oligomeric hemicelluloses present in the extract precipitated together with some lignin and oligo-glucose (glucans). The classical iodine test confirmed that most of the glucans are actually starch. Oligo-glucose is the major component in the precipitate from extracts produced at 150°C and below, while xylan is the main component at 160°C. Almost all lignin in the precipitate is in the form of lignin–carbohydrate complexes. The average M w of the carbohydrates isolated from the extract decreases with increasing autohydrolysis temperature. The average DP of hemicelluloses isolated from the extract decreases from about 71 to 36 over the temperature range from 130 to 170°C during 100min autohydrolysis. [ABSTRACT FROM AUTHOR]

This communication presents a process for thermal deoxygenation (TDO) to upgrade levulinic acid whereby levulinic acid is neutralized with calcium hydroxide, and the resulting salt is heated to between 350 °C and 450 °C. The cyclic and aromatic products have low oxygen to carbon ratios, improved energy density, and may be candidates for upgrading to hydrocarbon fuels. The process may be useful for converting biomass-derived levulinic acid in an integrated forest products complex based on a kraft pulp mill which uses a lime cycle to regenerate calcium hydroxide. [ABSTRACT FROM AUTHOR]

Lignin and ash material balances of SO 2 -ethanol–water (AVAP®) fractionation of sugarcane (SC) straw were thoroughly studied at various conditions. Most of straw lignin and ash dissolve in the liquor and 40–80% of lignin is precipitated after ethanol removal as a pure (∼99%) and sulfur-lean (<2%) fraction. Most of the acid-soluble ash and its elements (Na, K, Fe, Al) as well as large portion of silica are removed from the fiber phase. Straw lignin behavior exhibited differences compared to wood lignin including high apparent content in fiber, higher degree of sulfonation of dissolved lignin, and dense char-like precipitate formation upon ethanol removal. Variation in fractionation conditions did not have significant effect on lignin properties, while post-sulfonation was capable of changing its form from char-like to colloidal precipitate. [ABSTRACT FROM AUTHOR]

The sulfur balance of SO 2 -ethanol-water (AVAP®) fractionation of sugarcane (SC) straw was investigated. Hydrogen sulfite and sulfite anions are nearly absent in the liquors, despite cations present in straw, whose effect is thus limited to neutralization of lignosulfonic acids decreasing the acidity. Higher degree of sulfonation was observed for dissolved straw lignin compared to wood lignin (0.8–0.9 vs. 0.25 S/C9). Sulfur dioxide amounts of 0.9–1.2, 4.1–4.3 and 44–49 g per o.d. kg straw were bound to pulp, precipitated lignin and lignosulfonic acid, respectively, while the rest of SO 2 was recovered by distillation from the spent fractionation suspensions. [ABSTRACT FROM AUTHOR]

Lignocellulosic feedstocks are a potential renewable resource for the production of liquid fuels and chemicals. As a major by-product of the pulping industry, lignin is an underutilized source of organic carbon in lignocellulosic biomass. Residual lignin remaining in pulp after cooking of lignocellulosic biomass is typically removed during the bleaching stage of a pulping operation. This stage is composed of a sequence of steps including oxidation and alkaline extraction. Given that muconic acid and formic acid are formed during oxygen treatment of alkaline solutions of lignin, fast pyrolysis coupled with gas chromatography–mass spectrometry (Py–GC/MS) of alkali/alkaline earth salt mixtures of muconic acid and formic acid was employed to produce significantly deoxygenated products, such as cyclic ketones, hydrocarbons, aromatics, and phenolics. The cations investigated in this study were sodium, calcium, and magnesium to observe the difference in product distribution, volatile formation, and the formation of carbonaceous residue. The compounds observed after pyrolysis of the various salts suggest that along with the expected intramolecular condensation reactions, free radical reactions are likely occurring at the temperatures investigated explaining the observed alkylation and hydrogenation of the vapor products beyond deoxygenation which can be expected from reactive hydrogen formed by formate decomposition. Hydrogenation may also be occurring as a result of catalytic effects of the metal cations on the pyrolysis vapors. Pyrolysis of calcium muconate favors cyclic ketone formation almost exclusively, and when formate is added a 61 wt% reduction in carbonaceous residue formation is observed at 550 °C in a thermogravimetric analyzer (TGA) equipped with an evolved gas analyzer furnace (EGA). The highest yields of gaseous species were observed for the magnesium muconate–formate mixture, approximately 47 wt%, while the least amount of carbonaceous residue was formed upon pyrolysis of the sodium muconate–formate mixture, both at 550 °C in a TGA. The data suggests that pyrolysis at 550 °C of sodium formate and oxidized lignin mixtures may be of interest for the production of aromatic compounds. [ABSTRACT FROM AUTHOR]

In the present study the advantages of multistage oxygen delignification was explored in comparison with a single-stage process at the same level of total caustic charge. A pine kraft pulp with kappa number of 65 (Kn65) was bleached with the focus on the effect of NaOH-charge distribution on Kn, pulp yield, and selectivity of oxygen delignification. The effect of initial chelation with ethylenediaminetetraacetic acid (EDTA) and interstage pulp treatment with peroxymonosulfuric acid (Px) were also investigated. It is shown that the chelated pulp with high Kn may be delignified in three stages to Kn15, but at an unacceptable reduction in pulp viscosity and yield. In contrast, interstage treatment of the chelated pulp with Px at a total charge of 2% active oxygen (based on pulp) in combination with three stages of oxygen delignification enables Kn reduction to about 15 at acceptable viscosity and total yield advantage of about 0.5% (based on wood) compared to an oxygen-delignified kraft pulp with Kn24 derived from the same pine wood chips. [ABSTRACT FROM AUTHOR]

The delignification kinetics anddelignification/carbohydratesdegradation selectivity of oxygen delignification (O-delignification)of a high kappa number (HKn) pine kraft pulp (kappa 65) were studiedat different alkali concentrations (1–4 g NaOH/L), temperatures(95–105 °C), oxygen pressures (5–10 bar), and reactiontimes (5–90 min) in a flow-through (FT) reactor. This continuousmixed batch reactor operating at constant and relatively low alkaliconcentration allows degree of lignin removal greater than 70% athigher yield (about 2% on wood) where the final kappa number is ∼15equal to that of oxygen-delignified conventional kraft pulp. In addition,the effect of operational conditions on delignification, cellulosedegradation, and pulp yield are compared to that of oxygen-delignifiedconventional kraft pulp. [ABSTRACT FROM AUTHOR]

Highlights: [•] Softwood and hardwood biomass is fractionated by SO2–ethanol–water technology. [•] Hemicellulose dissolution rate is similar for softwood and hardwood. [•] Biomass (branches etc.) fractionation is compared with stem wood fractionation. [•] Softwood biomass delignification is inferior likely due to high amount of bark. [ABSTRACT FROM AUTHOR]

The focus of this study is to develop a process for conditioning spent liquor produced by SO2–ethanol–water (SEW) fractionation of spruce chips/softwood biomass for fermentation to butanol, ethanol, and acetone/2-propanol (so-called ABE process) by Clostridia bacteria. This study is an integral part of a project which aims at creating an economic process that can utilize cheap forestry residues such as twigs, cones, treetops, branches, and bark to produce renewable chemicals and liquid fuels. The results of this study suggest that the proposed scheme for conditioning of SEW spent liquor from spruce/softwood biomass can be successfully applied to produce chemicals and biofuels by ABE fermentation. Butanol, acetone, and ethanol are produced at a total yield of around 0.25 g/g sugars. [ABSTRACT FROM AUTHOR]

Abstract: The present study proposes the use of market rejected and waste vegetables as a supplement for improved acetone–ethanol–butanol (ABE) solvent production. In the present study, three different perishable vegetables were evaluated as supplements for ABE fermentation. These vegetables were found to stimulate the solvent production at as low as 1% (w/v) concentration. The supplementation showed improved production of solvents using 4-fold diluted SO2–ethanol–water (SEW) spent liquor supplemented with 25g/l glucose as a substrate. The maximum total solvent production obtained with 5% (w/v) supplementation of carrot, cabbage and tomato was 9.96g/l, 10.49g/l and 10.65g/l, respectively as compared to the control value of 7.43g/l. The applicability of vegetables was successfully evaluated as a complex medium for solvent production. [Copyright &y& Elsevier]

Clostridium beijerinckii DSM 6423 was studied using different continuous production methods to give maximum and stable production of isopropanol and n-butanol. In a single-stage continuous culture, when wood pulp was added as a cell holding material, we could increase the solvent productivity from 0.47 to 5.52 g L h with the yield of 54% from glucose. The overall solvent concentration of 7.51 g L (39.4% isopropanol and 60.6% n-butanol) with the maximum solvent productivity of 0.84 g L h was obtained with two-stage continuous culture. We were able to run the process for more than 48 overall retention times without losing the ability to produce solvents. [ABSTRACT FROM AUTHOR]

SO2-ethanol-water (SEW) delignification kinetics for spruce, beech, and wheat straw are presented. All these species produce pulps using SEW cooking liquor and follow first order delignification kinetics at similar bulk delignification rates. However, residual delignification is much slower for beech than for spruce. The hemicelluloses retention (135°C) and cellulose degradation kinetics are also characterized for beech SEW pulping. Xylan and glucomannan are removed from the pulp following first-order kinetics with a higher rate constant for xylan. Cellulose is retained in the fibers until kappa number 9, after which it starts to dissolve in the liquor. The yield also drops significantly in the region of kappa numbers 9-7. Cellulose degradation is followed by intrinsic viscosity measurements and is found to be zero order in cellulose. The rates are higher at 135 and 145°C for beech SEW pulping than for spruce. [ABSTRACT FROM AUTHOR]

The overall target of this project, called Bioforest, is to develop an economic process for the production of commodity chemicals from mixed forest biomass, consisting of logging residues of hardwoods (HW) and softwoods (SW) and also from recycled fibers. The aim is to dissolve the biomass lignin and to produce monosugars based on hemicelluloses and hydrolyzed cellulose in high yield. The hydrolyzate could subsequently be converted into chemicals by modified acetone-butanol-ethanol fermentation. Here, the total mass balances of SO2-ethanol-water fractionation of different types of biomass feedstocks, such as SW and HW biomass, and deinked pulp are presented. Chemical composition of the feedstocks, solid residues (pulps) and spent liquors of fractionation were analyzed to gain more understanding about the fractionation procedure. The analysis was focused on carbohydrates, lignin, ash, acetyl groups and sugar degradation products. It was also examined if all feedstocks could be treated simultaneously in one digester because a larger feedstock supply within an economic transport radius improves the viability of the process. The fractionation approach was successful and it can be concluded that the method presented is very versatile for future applications in lignocellulosic biorefineries. [ABSTRACT FROM AUTHOR]

In a forest based biorefinery, pulp and paper are the main products, while side-streams are utilized for value-added products. One biorefinery concept is to remove hemicelluloses from wood by extraction prior to pulping and converting them into biofuels or chemicals. This study presents a concept of a larch wood based biorefinery and focuses on the mass balance of pre-extraction. Sugar rich extracts were obtained by hot water extraction of Siberian larch ( Larix sibirica Lebed.) wood chips at different temperatures and times. At 160°C and 60-90 min the extract contains 13-16% hemicelluloses (on wood). The composition of extracts and extracted wood has been determined to have a basis for mass balances. Fermentation of the hydrolyzed extract with Bacillus coagulans MXL-9 resulted in consumption of all C6 and C5 sugars and produced lactic acid in high yield. In an earlier work, it was demonstrated that water pre-extraction of larch chips followed by polysulfide-anthraquinone (PSAQ) pulping still produced a good papermaking pulp at a yield comparable to the corresponding non-extracted kraft pulp. Accordingly, the present results show that a larch wood based biorefinery has a potential for industrial application. [ABSTRACT FROM AUTHOR]

Bacillus coagulans MXL-9 was found capable of growing on pre-pulping hemicellulose extracts, utilizing all of the principle monosugars found in woody biomass. This organism is a moderate thermophile isolated from compost for its pentose-utilizing capabilities. It was found to have high tolerance for inhibitors such as acetic acid and sodium, which are present in pre-pulping hemicellulose extracts. Fermentation of 20 g/l xylose in the presence of 30 g/l acetic acid required a longer lag phase but overall lactic acid yield was not diminished. Similarly, fermentation of xylose in the presence of 20 g/l sodium increased the lag time but did not affect overall product yield, though 30 g/l sodium proved completely inhibitory. Fermentation of hot water-extracted Siberian larch containing 45 g/l total monosaccharides, mainly galactose and arabinose, produced 33 g/l lactic acid in 60 h and completely consumed all sugars. Small amounts of co-products were formed, including acetic acid, formic acid, and ethanol. Hemicellulose extract formed during autohydrolysis of mixed hardwoods contained mainly xylose and was converted into lactic acid with a 94% yield. Green liquor-extracted hardwood hemicellulose containing 10 g/l acetic acid and 6 g/l sodium was also completely converted into lactic acid at a 72% yield. The Bacillus coagulans MXL-9 strain was found to be well suited to production of lactic acid from lignocellulosic biomass due to its compatibility with conditions favorable to industrial enzymes and its ability to withstand inhibitors while rapidly consuming all pentose and hexose sugars of interest at high product yields. [ABSTRACT FROM AUTHOR]

The "near neutral hemicellulose extraction process" involves extraction of hemicellulose using green liquor prior to kraft pulping. Ancillary unit operations include hydrolysis of the extracted carbohydrates using sulfuric acid, removal of extracted lignin, liquid-liquid extraction of acetic acid, liming followed by separation of gypsum, fermentation of C5 and C6 sugars, and upgrading the acetic acid and ethanol products by distillation. The process described here is a variant of the "near neutral hemicellulose extraction process" that uses the minimal amount of green liquor to maximize sugar production while still maintaining the strength quality of the final kraft pulp. Production rates vary between 2.4 to 6.6 million gallons per year of acetic acid and 1.0 and 5.6 million gallons per year of ethanol, depending upon the pulp production rate. The discounted cash flow rate of return for the process is a strong function of plant size, and the capital investment depends on the complexity of the process. For a 1,000 ton per day pulp mill, the production cost for ethanol was estimated to vary between $1.63 and $2.07/gallon, and for acetic acid between $1.98 and $2.75 per gallon depending upon the capital equipment requirements for the new process. To make the process economically attractive, for smaller mill sizes the processing must be simplified to facilitate reductions in capital cost. [ABSTRACT FROM AUTHOR]

Extraction of hemicelluloses from wood prior to pulping is being pursued to generate more value-added products, while still producing high quality pulp from the pre-extracted wood. For a better understanding of the factors limiting selective extraction, enzymatic hydrolysis in combination with size exclusion chromatography (SEC) was applied to milled wood and hydrothermally treated wood. Complete dissolution was achieved in a lithium chloride/dimethylacetamide solvent system after mild ballmilling of a Southern Hardwood Mixture (SHM), of SHM extracted using auto-hydrolysis, and of enzyme-treated SHM. SEC tests showed that severe degradation of wood polymers occurred after a milling time of 3 hours. The SEC data also confirmed the presence of lignin-carbohydrate complexes. Based on the results, it is suggested that linkages between lignin and polysaccharides may play an important role in limiting extraction of hemicelluloses. [ABSTRACT FROM AUTHOR]

SO2-ethanol-water (SEW) pulping is a promising fractionation process for lignocellulosics to produce pulp and value-added chemicals as a contribution to the concept of forest biorefinery. The presence of SO2 leads to dissolution of hemicelluloses in high yield mostly as monomeric sugars, while lignin becomes soluble through sulfonation. After lignin removal, the dissolved sugars may be used as feedstock for fermentation to ethanol or butanol. SEW pulping may be considered a hybrid between solvent pulping (organosolv pulping by solvolysis) and acid sulfite pulping. Absence of an inorganic base leads to simplification of the recovery cycle. Furthermore, alcohol increases the impregnation rate of dissolved SO2 into wood, so that a separate impregnation phase is not necessary. Also, the presence of SO2 allows cooking of softwoods, while ethanol pulping is limited to hardwoods. Thus, SEW pulping may be applied to a wide variety of lignocellulosics at lower temperatures and similar cooking times than those used in kraft pulping. In the present study, SEW pulping experiments were performed on spruce chips at cooking temperatures of 135–165°C with a 12% SO2 solution at a liquor-to-wood ratio of 6:1 l kg-1. The effect of cooking temperature and time on kappa number, yield, and intrinsic viscosity of the pulp was determined. Based on these results, the kinetics of delignification, hemicelluloses removal, and cellulose hydrolytic destruction were established. [ABSTRACT FROM AUTHOR]

Special oxygen delignification experiments were performed in a differentially operated continuous stirred tank reactor (CSTR). Because the dissolved oxygen and alkali concentrations in the reactor are constant, the rate of lignin removal may be determined from the dissolved lignin content in the outflow stream measured by UV absorption. The delignification kinetics were determined at different temperatures, oxygen pressures and caustic concentrations on softwood kraft pulps of different kappa numbers. The kinetics are first order in residual lignin content [hexenuronic acid (HexA) corrected], and follow a Langmuir-type behavior for adsorption of oxygen on the active aromatic lignin sites. The first order in residual lignin content implies that the active lignin sites are uniformly distributed and have the same reactivity. It is proposed that the active site is the 3 carbon of the aromatic ring, where oxygen reacts to form a hydroperoxide, with a p Ka of almost 2 units higher than that of phenolic lignin. The kinetics of phenolic delignification can be described by assuming that the reaction between adsorbed oxygen and carbon 3 of the aromatic ring is the rate determining step. Alternatively, the decomposition of the hydroperoxide anion is rate determining. Peeling delignification has been proposed as an additional delignification route by peeling of hemicelluloses which have lignin fragments covalently bound to them. It is shown that the impact of peeling delignification is relatively small and limited to the initial delignification phase. Finally, data are presented showing that radicals may provide an essential contribution to delignification by their removal of non-lignin and non-HexA oxidizable structures contributing to the kappa number. [ABSTRACT FROM AUTHOR]

Sheet Molding Compound, (SMC), is a composite material comprised of an unsaturated crosslinked polymer, reinforcing fiber such as glass, thermoplastic processing aids, mineral fillers, and lubricant (release agent). Mechanical properties for service requirements are developed through fiber reinforcements randomly aligned in between two polymer sheets. Service requirements for the SMC material are necessary for specified amounts of time. For example, SMC used for automotive parts have upwards of a 10 year service life; therefore, the study of how the SMC material changes with time and environmental exposure is of interest. In the current study, hygrothermal aging is used to accelerate normal environmental aging and dynamic mechanical thermal analysis (DMTA) is used to study the mechanical and chemical changes as a function of temperature and aging time. Results from the current study show through high performance liquid chromatography (HPLC) analysis that poly(vinyl acetate) (PVAc) does not chemically react with water in the SMC material and DMTA data show that water has two roles in the thickening reaction in the SMC between MgO and carboxylic acid functional groups adding an additional step to what has been previously reported. [ABSTRACT FROM AUTHOR]

The enzymatic hydrolysis of hardwood and softwood harvest residues treated by SO2-ethanol-water (SEW) fractionation was studied. The target was to convert these fibers with high yield into glucose monomers which could be further converted into biofuel by a subsequent fermentation stage. Hardwood biomass residues were efficiently digested at low enzyme dosage (5 FPU/g cellulose) whereas the softwood residues required notably higher enzyme dosage (20 FPU) for sufficient conversion. However, cellulase dosage of softwood could be reduced mannanase supplementation. Especially the high lignin content of softwood biomass pulps impairs the digestibility and thereby, improved delignification could notably enhance the hydrolysis yields. It was shown that inferior delignification of SW biomass is due to persistent polyphenolic acids present in coniferous bark, whereas no evidence of the negative effect of inorganics and acetone extractives was observed. Additionally, SW hydrolyzate was successfully converted into a mixture of butanol, acetone and ethanol through ABE fermentation. [ABSTRACT FROM AUTHOR]

The focus of this study was to find out the effect of bark on SO2–ethanol–water (SEW) fractionation and enzymatic hydrolysis of forest biomass. Softwood bark was found to be more harmful than hardwood bark in both processes. For softwood, the amount of undigested wood in SEW fractionation increased with the increasing bark content, whereas the hardwood bark did not impair the fractionation of wood. The higher the softwood bark content was the lower were the yields in enzymatic hydrolysis likely due to the unproductive binding of enzymes on lignin and other compounds. Addition of surfactant Tween 20 (2% w/w on substrate) prior to enzyme more than doubled the sugar yield of bark-rich softwood pulp. Hardwood bark impaired enzymatic hydrolysis when its share was over 28%. According to a preliminary study, lignosulfonates from the carry-over liquor seem to improve the sugar yield in the enzymatic hydrolysis by acting as a surfactant. [ABSTRACT FROM AUTHOR]

Highlights: [•] Nanofibrils (LCNF) were produced from softwood after SEW fractionation. [•] The effect of lignin and hemicelluloses on LCNF bioconversion was elucidated. [•] Enzyme binding and activity on LCNF was monitored in situ by QCM-D. [•] Hydrolysis of SEW LCNF produce sugar yields higher than those of fibers. [•] SEW-based biorefinery may integrate nanomaterial and biofuel production. [Copyright &y& Elsevier]

A mixture of US southern hardwood chips was treated with aqueous acetic and formic acid (FA) solutions in a modified Dionex ASE100 extractor. The amount and selectivity of hemicelluloses dissolution increase at higher acetic acid (AA) and FA concentrations, but cellulose remains intact in the residual wood. Even at the highest AA concentration of 100 g l-¹, the dissolved hemicellulose fragments are still oligomeric except for arabinose. The formation of lignin-like condensation products (LCPs) and decomposition of dissolved mannose, arabinose, and galactose were observed at the highest AA concentration. Sugar hydrolysis is more pronounced with the addition of FA at increasing temperature. The concentration of xylose in the FA extract is approximately the same as that of xylooligomers at 160°C. Formation of LCPs is only observed at 170°C during 10 g l-¹ FA treatment. The concentrations of dissolved wood components increase linearly with increased recycling of the FA extract. [ABSTRACT FROM AUTHOR]

Inthis study a forest biorefinery concept based on larch woodwas technically and economically evaluated. Two slightly differentcases of a larch-based biorefinery were compared to conventional kraftpulping. The wood chips of Larix sibirica(Lebed.) were pre-extracted (PE) and washed with water prior topulping, in order to generate an additional sugar side-stream. Thesugars were hydrolyzed into monosugars, which were then fermentedby Bacillus coagulansinto lactic acid.The lactic acid needs to be purified before sold to the market. Bypulping the pre-extracted wood chips with anthraquinone (AQ) and polysulfide(PS), the pulp yield loss was reduced. The pulp was then bleached(O-D0-Ep-D1-P). The products of this larch biorefinery are bleachedsoftwood pulp and lactic acid. Three process cases were simulated:conventional kraft pulping, PE-PSAQ with 0.5% PS, and PE-PSAQ with2% PS, in terms of mass and energy balances. Considering the availabilityof larch resources, this kind of a biorefinery could suitably be locatedin Siberia, Russia. Market prices were collected, and based on thesimulation results, cash flows were determined. Sensitivity analysiswas carried out, and investment costs were estimated. Based on thesimulation with the addition of a lactic acid production line to anexisting pulp mill, the payback time for the investment costs wouldbe about 16 months. [ABSTRACT FROM AUTHOR]

Highlights: [•] Oil palm empty fruit bunches (OPEFB) are fractionated by SO2–ethanol–water mixture. [•] Fractionation of OPEFB feedstock produces cellulosic fibers and spent liquor. [•] Spent liquor contains dissolved hemicellulose sugars (mostly monomers) and lignin. [•] Fractionation and sugar hydrolysis is hindered by the high cation content of OPEFB. [•] Acidic leaching of OPEFB only partly removes cations; more intense deashing needed. [Copyright &y& Elsevier]

Inthe current study, a simple two-step fractionation process was developedfor utilization of hardwood biomass without forming troublesome stickylignin condensation products. The four product streams generated area hemicellulose extract, a lignin extract, separated wood fibers (pulp)and wood fiber bundles (rejects). All four product streams can befurther utilized for production of transportation fuel, chemicals,and biomaterials. The optimum fractionation conditions for mixed southernhardwood chips are the following: extraction with 10 g/L formic acid(FA) at 160 °C for 90 min followed by extraction with 50% (w/w)EtOH at 80 °C for 90 min. The yield of pulp and reject fibersthat are produced from the FA and EtOH pre-extracted wood chips bymechanical action are 38% and 28%, respectively. Cellulose to glucoseconversion yield of the FA treated wood, as well as that of the finalpulp and fiber bundles by enzymes, are strongly improved comparedto that of the original hardwood chips. [ABSTRACT FROM AUTHOR]

Abstract: SO2–ethanol–water (SEW) spent liquor from spruce chips was successfully used for batch and continuous production of acetone, butanol and ethanol (ABE). Initially, batch experiments were performed using spent liquor to check the suitability for production of ABE. Maximum concentration of total ABE was found to be 8.79g/l using 4-fold diluted SEW liquor supplemented with 35g/l of glucose. The effect of dilution rate on solvent production, productivity and yield was studied in column reactor consisting of immobilized Clostridium acetobutylicum DSM 792 on wood pulp. Total solvent concentration of 12g/l was obtained at a dilution rate of 0.21h−1. The maximum solvent productivity (4.86g/lh) with yield of 0.27g/g was obtained at dilution rate of 0.64h−1. Further, to increase the solvent yield, the unutilized sugars were subjected to batch fermentation. [Copyright &y& Elsevier]

The objective of this study is to develop a process for conditioning spent liquor produced by SO2-ethanol-water (SEW) fractionation of spruce wood chips for fermentation to butanol, ethanol and acetone/isopropanol, i.e., by means of the so called acetone-butanol-ethanol (ABE) process using Clostridia bacteria. This study serves as part of an overall project aiming at the development of economic processes for producing chemicals and biofuels from mixed forest biomass via SEW fractionation and ABE fermentation technologies. [ABSTRACT FROM AUTHOR]

Abstract: Nanocalorimeters based on a micromachined hotplate platform were characterized for potential applications in catalyst screening and reaction mechanism studies. The nanocalorimeters were designed to limit heat loss to the surroundings, resulting in a small heat capacity (50nJK−1) and thermal time constant (1ms). This greatly increases the sensitivity of the device, allowing reaction heat flows on the order of <1μW to be measured in air. The Pt catalyzed combustion of hydrogen in air was used as a model reaction. A relatively-simple heat and mass transfer model was developed which accurately described the data from the microscale system, and the rate-limited and mass transfer-limited regimes of the ignition traces were clearly distinguished. An average activation energy of 48±4kJmol−1 was determined for the Pt catalyzed combustion of hydrogen in air. However, unique rapid temperature programmed calorimetry methods convincingly demonstrate that the activation energy is influenced by kinetic phase transitions which also result in reaction rate bistabilities and oscillations. [ABSTRACT FROM AUTHOR]

Abstract: The carbohydrate composition of lignocellulosic biomass is normally obtained by the quantification of monomers after two stages of hydrolysis in H2SO4. A new two-stage hydrolysis protocol has recently been developed but so far only results for temperate hardwoods have been reported. In this investigation the new protocol was used in the analysis of depithed sugarcane bagasse, Eucalyptus grandis and bamboo. The results were compared to those from the traditional hydrolysis protocol. Sugar monomers were quantified by 1H NMR and high performance liquid chromatography (HPLC) and there were no significant differences between the two techniques. The new and traditional hydrolysis protocols gave nearly identical results for the bagasse and bamboo samples both of which contain <0.10 uronic acids per xylose unit. However, the new protocol gave a higher xylan yield (13.2% vs. 12.1%) for the E. grandis that contained >0.20 uronic acids per xylose units. For both hydrolysis protocols, summative analyses in the range of 97.5–101.0% were obtained for the three biomass samples. However, the range was narrower (98.6–99.5%) for the new hydrolysis protocol coupled with 1H NMR analysis. [Copyright &y& Elsevier]

Three lignins: Indulin AT, Lignoboost™, and Acetocell lignin, were characterized and pyrolyzed in a continuous-fed fast pyrolysis process. The physical and chemical properties of the lignins included chemical composition, heat content, ash, and water content. The distributed activation energy model (DAEM) was used to describe the pyrolysis of each lignin. Activation energy distributions of each lignin were quite different and generally covered a broad range of energies, typically found in lignins. Process yields for initial continuous-fed fast pyrolysis experiments are reported. Bio-oil yield was low, ranging from 16 to 22%. Under the fast pyrolysis conditions used, the Indulin AT and Lignoboost™ lignin yielded slightly more liquid product than the Acetocell lignin. Lignin kinetic parameters and chemical composition vary considerably and fast pyrolysis processes must be specified for each type of lignin. [ABSTRACT FROM AUTHOR]

A pre-hydrolysis step to remove hemicelluloses from mixed hardwood chips consisting of maple, aspen, and birch with a ratio of 7:2:1 has been carried out. The effects of parameters on the pre-hydrolysis such as time, temperature, acetic acid addition, and raw material species, were determined. Different sugars, acetic acid, and furfural formation in the pre-hydrolysis liquor were quantified. The results showed that the pre-hydrolysis is a dynamic process, in which the removal of hemicelluloses increased with time while the conversion of extracted hemicelluloses to monosaccharides due to acid hydrolysis increased and part of the xylose was converted to furfural. The maximum temperature was the most critical parameter for hemicelluloses extraction and conversion, and a temperature of 170°C was the optimum for hemicelluloses extraction with relatively low conversion of xylose to furfural. About 11% of the xylan (in both monomeric and oligomeric forms) was removed at 170°C. Due to the presence of a high amount of xylan, birch produced the highest amount of xylose, followed by maple, and then aspen. [ABSTRACT FROM AUTHOR]

Hardwood hemicellulose extracts can be used as a feed stock for ethanol plants or for renewable polymer applications. Extraction of Acer rubrum wood strands with water at 160°C and for 90 minutes removed approximately 16% of the wood weight. The extract was composed primarily of acetylated glucuronoxylans (63.9%) and lignin (17.6%). The dispersive surface energy and acid-base surface characteristics for a multi-component freeze dried mixture of hot water extracted Acer rubrum components was determined by inverse gas chromatography (IGC). The dispersive surface energy of the extract was found to be non-sensitive to thermal variations and has a magnitude of 34.6 ± 0.2 mJ/m2 with a Ka of 0.13 and Kb of 0.46. The maple wood had a regressed surface energy of 42.7 mJ/m2 at 20°C following extraction, and the surface energy before extraction was 40.4 mJ/m2 at 20°C. Also, before extraction the Ka and Kb of the red maple were 0.19, 0.92, respectively, and after extraction the Ka and Kb were 0.15 and 1.17. Infrared spectroscopy (IR) was used to characterize the wood surfaces and the IR data correlated to the surface energy values. These findings indicate that the hemicellulose-extract components influence the overall average surface energy of maple wood by lowering the surface energy relative to other surface components. [ABSTRACT FROM AUTHOR]