Kang, Peng; Qin, Wu; Zheng, Zong-Ming; Dong, Chang-Qing; Yang, Yong-Ping
Theoretical study on the mechanisms of cellulose dissolution and precipitation in the phosphoric acid-acetone process
CARBOHYDRATE POLYMERS, 90:1771-1778, NOV 6 2012

Phosphoric acid-acetone fractionation was applied to pretreat lignocellulose for production of cellulosic ethanol. Cellulose solubility properties in H2O, H3PO4 and CH3COCH3 were simulated. Atomic geometry and electronic properties were computed using density functional theory with local-density approximation. H3PO4 molecule is adsorbed between two cellulose segments, forming four hydrogen bonds with E-B of -1.61 eV. Density of state for cellulose in H3PO4-cellulose system delocalizes without obvious peak. E-gap of 4.46 eV is much smaller than that in other systems. Molecular dynamics simulation indicates that fragments of double glucose rings separate in the cellulose-H3PO4 interaction system. Icy CH3COCH3 addition leads to re-gathering of separated fragments. Reaction energy of cellulose in three solvents is around 3.5 eV, implying that cellulose is chemically stable. Moreover, theoretical results correspond to the experiments we have performed, showing that cellulose dissolves in H3PO4, flocculates after CH3COCH3 addition, and finally becomes more liable to be hydrolyzed into glucoses. (C) 2012 Elsevier Ltd. All rights reserved.

DOI:10.1016/j.carbpol.2012.07.068

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