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Multi-level dissolution and hydrolysis of lignocellulosic waste with a semi-flow hydrothermal system

Zhao, Yan, Tan, Haobo, Xu, Yingjie, Zou, Lei
Bioresource technology 2016 v.214 pp. 496-503
cellulose, corn stover, crystal structure, ethanol production, hydrolysis, lignin, lignocellulose, sugars, wastes, xylan
The hydrothermal process is efficient in lignocellulosic conversion and is beneficial to potential bioethanol production. In batch- and flow-type processes, concurrent dissolution and hydrolysis of lignocellulose result in product loss and inhibitory intermediates. Therefore, multi-level hydrothermal conversion of corn stalks was implemented with a semi-flow system to provide different residence times to undissolved compounds and facilitate dissolution or hydrolysis at respective optimal conditions. First-stage dissolution dissolved amorphous hemicellulose and lignin at 195–200°C. Xylan, acid soluble lignin, and part of Klason lignin were dissolved without affecting glucan. In second-stage dissolution, the crystallinity of the undissolved materials suddenly decreased at 245–250°C. The cellulose dissolution ratio was higher than 75%. Soluble sugars were obtained after the hydrolysis of dissolved cellulose at 280°C. The results provide significant information on the multi-level hydrothermal process and its potential applications for recovering valuable chemicals from lignocellulosic waste.