KINETIC MODELING OF HARDWOOD PREHYDROLYSIS. PART III. WATER AND DILUTE ACETIC ACID PREHYDROLYSIS OF SOUTHERN RED OAK

摘要: The hemicelluloses in wood are more readily hydrolyzed than is cellulose. Because it advantageous to process the hemicellulose sugars separately from glucose obtained cellulose, most processes for utilizing as a source of chemicals and liquid fuels include prehydrolysis step remove hemicelltdose prior main hydrolysis cellulose glucose. Kinetic data required model reactions that occur during so optimum conditions product mixes can be predicted. Two promising methods, Iotech steam explosion Stake process, based on water (autohydrolysis). kinetics dilute (5%) acetic acid southern red oak over temperature range 170 240 C were investigated. parameters determined permitted modeling not only xylan removal but also occurrence oligosaccharides, free xylose, furfural, further degradation products prehydrolyzate. At lower temperatures (approximately 200 C), could modeled sum two parallel (one an easily portion one resistant xylan) using equation derived Part I. highest studied (236.9 was best single reaction with small fraction being essentially nonreactive. prehydrolyzate consecutive, irreversible pseudo first-order reactions. A timelag associated depolymerization oligosaccharides xylose accounted by allowing apparent rate constant formation increase exponentially time maximum value. Increasing decreased overall occur, increased removed wood, yield total anhydroxylose units (xylose + oligosaccharides) recovered Prehydrolysis does greatly affect yields those observed prehydrolysis; however, decreased. presented this report indicate that, at higher temperatures, or gives comparable sulfuric recently reported literature. Preliminary results lignin isolated residues confirm recent reports lignins type useful phenol substitutes phenolformaldehyde adhesives.