|
Poster Presentation 1-28
The Effect of Lignin Contents and S/G Ratio in Populus on the Release of Fermentable Sugars During Dilute Acid Hydrolysis
N. P. Nghiem1, B. H. Davison1, G. A. Tuskan1, L. E. Gunter1, C. L. Cheng2 and S. R. Drescher1
1Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831
2Eli Lilly and Company, Indianapolis, Indiana 46285
Telephone: (865) 574-1184; Fax: (865) 574-6442; E-mail: nghiemnp@ornl.gov
Samples of Populus having different lignin contents and S/G ratio (S: Syringyl-like lignin structures; G: Guaiacyl-like lignin structures) were hydrolyzed with dilute sulfuric acid to release fermentable sugars. The lignin contents varied from 22.7 to 25.8% and the S/G ratio from 1.8 to 2.3. The hydrolysis conditions (1w% solids, 1w% acid, 175°C maximum, 12-minute hydrolysis time) were chosen to achieve only partial hydrolysis of the hemicellulosic fraction. The yield values of xylose were calculated and subjected to statistical analysis. The results indicated that both lignin contents and S/G ratio had significant effects on the yield of xylose. For example, the xylose yield of the 25.8% lignin and 2.3 S/G (high lignin, high S/G) sample was 30.1% of theoretical yield, and the xylose yield of the 22.7% lignin and 1.8 S/G (low lignin, low S/G) was 54.9% of theoretical yield. Interaction between lignin contents and S/G ratio also was observed. The residual solids obtained at the end of the acid hydrolysis were hydrolyzed with an industrial cellulase. Neither lignin contents nor S/G ratio seemed to have an effect on the rate of enzymatic hydrolysis of these solids.
|