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Oral
Presentation 3-02 A Comparison of Batch and Flowthrough Reactors for Dilute Acid Hydrolysis of Corn
Stover Hemicellulose Bin
Yang, Chaogang Liu, Michael A. Brennan, and Charles E.
Wyman Thayer School of Engineering Dartmouth College HB 8000 Cummings Hall Hanover,NH
03755 Telephone: (603) 646-3193; Fax: (603) 646-2277; E-mail: charles.e.wyman@dartmouth.edu Dilute acid hydrolysis of hemicellulose in
co-current reactors (e.g., catalyzed steam explosion) offers relatively high
yields of hemicellulose sugars but is presently among the most costly steps in
biological ethanol production.
Flow-through and countercurrent reactors have important advantages
including reduced chemical use, higher hemicellulose sugar yields, and much
better cellulose digestibility, but suffer from high water use. Comparative data is reported on sugar,
lignin and overall mass dissolution and recovery profiles for corn stover
pretreated in batch and flowthrough reactors with varying temperature, acid
concentration, and solids concentration or flowrate. Particular attention is focused on tracking of oligomers because
these elusive species could hold the keys to differentiating these
systems. A heat up strategy was
developed for the batch reactor to insure its results would be consistent with
isothermal operation at the target temperature. Acid addition improved solubilization in both systems, but the
flow-through reactor always removed more hemicellulose, lignin, and overall
mass. In addition, while lignin removal
would increase to about 10% in the batch system and then drop back to virtually
zero, about half of the lignin was removed for the flow-through process. Furthermore, dissolution increased with
increasing flow rate for the flow-through system.
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