- 12:50 PM
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Flexible Biorefinery for Producing Value-Added Streams: Evaluation of the Cellulose Stream as a Source of Sugars and Pulp

Kiran L. Kadam, Richard Wingerson, Lawrence Brown, and Ed Lehrburger. PureVision Technology, 511 N. McKinley Ave., Fort Lupton, CO 80621

PureVision Technology, Inc. is developing a process for the fractionation of lignocellulosic biomass into three streams. This is achieved via two coupled reactors, one each for the two stages in a continuous process. Hemicellulose is hydrolyzed in the first stage, which also performs in situ solid/liquid (S/L) separation at operating temperatures, and yields a liquid stream rich in hemicellulosic sugars. Lignin hydrolysis subsequently occurs in the second stage. The slurry obtained from this stage undergoes external S/L separation to yield the other two product streams: a lignin-rich liquid stream and a solid cellulose stream. Enzymatic hydrolysis of this relatively pure cellulose stream requires significantly lower enzyme loadings because of minimal enzyme deactivation from nonspecific binding to lignin. Also, at a given insoluble solids loading, higher cellulose content of the solids results in higher ethanol titer, which translates into significant energy savings during distillation. The cellulose produced is also low-enough in lignin to be used alternatively as market pulp. As corn stover and wheat straw are similar to hardwoods in fiber length, they can partially replace hardwood fiber in pulp blends. This approach potentially yields a higher value commodity and, unlike ethanol, does not require additional processing such as hydrolysis or fermentation. This paper will discuss process development efforts in realizing a flexible biorefinery that can be steered toward the sugar platform or the pulp & paper platform. Specifically, results on the evaluation of the cellulose streams from corn stover and wheat straw for the above two applications will be covered.