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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]

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]

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]

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]

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]

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]