Kinetic modeling of hardwood prehydrolysis. Part III. Water and dilute acetic acid prehydorlysis of southern red oak

Journal Article · Tue Apr 01 04:00:00 EST 1986 · Wood Fiber; (United States)

OSTI ID:5260430

Conner, A L; Lorenz, L F

Most processes for utilizing wood as a source of chemicals and liquid fuels include a prehydrolysis step to remove the hemicellulose prior to the main hydrolysis of the cellulose to glucose. Two promising prehydrolysis methods, the Iotech steam explosion process and the Stake process, are based on water prehydrolysis (autohydrolysis). The kinetics of water and of dilute (5%) acetic acid prehydrolysis of southern red oak wood over the temperature range of 170 to 240 C were investigated. Kinetic parameters were determined that permitted modeling not only of xylan removal from the wood but also of the occurrence of xylan oligosaccharides, free xylose, furfural, and further degradation products in the prehydrolyzate. At lower temperatures (approximately 170 to 200 C), xylan removal could be modeled as the sum of two parallel reactions (one for an easily hydrolyzed portion and one for a more resistant portion of xylan) using the equation derived in Part I. At the highest temperature studied (236.9 C), the removal of xylan from the wood was best modeled as a single reaction with a small fraction of the xylan being essentially nonreactive. The occurrence of xylan oligosaccharides, xylose, furfural, and further degradation products in the prehydrolyzate was modeled as consecutive, irreversible pseudo first-order reactions. A timelag associated with the depolymerization of the xylan oligosaccharides to xylose was accounted for in the model by allowing the apparent rate constant for the formation of xylose to increase exponentially with time to a maximum value.

• Research Organization: Forest Products Lab., Madison, WI
• OSTI ID: 5260430
• Journal Information: Wood Fiber; (United States), Journal Name: Wood Fiber; (United States) Vol. 18:2; ISSN WOOFA
• Country of Publication: United States
• Language: English

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ACETIC ACID
ACID HYDROLYSIS
ALDEHYDES
CARBOHYDRATES
CARBOXYLIC ACIDS
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
DECOMPOSITION
DEPOLYMERIZATION
FURANS
FURFURAL
GLUCOSE
HEMICELLULOSE
HETEROCYCLIC COMPOUNDS
HEXOSES
HYDROLYSIS
KINETICS
LIGNIN
LYSIS
MATHEMATICAL MODELS
MONOCARBOXYLIC ACIDS
MONOSACCHARIDES
OAKS
OLIGOSACCHARIDES
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
PENTOSES
PLANTS
POLYSACCHARIDES
REACTION KINETICS
REMOVAL
SACCHARIDES
SOLVOLYSIS
STEAM
TREES
WOOD
XYLANS
XYLOSE