Heterogeneous aspects of acid hydrolysis of alpha-cellulose.
Hydrolysis of alpha-cellulose by H2SO4 is a heterogeneous reaction. As such the reaction is influenced by physical factors. The hydrolysis reaction is therefore controlled not only by the reaction conditions (acid concentration and temperature) but also by the physical state of the cellulose. As evidence of this, the reaction rates measured at the high-temperature region (above 200 C) exhibited a sudden change in apparent activation energy at a certain temperature, deviating from Arrhenius law. Furthermore, alpha-cellulose, once it was dissolved into concentrated H2SO4 and reprecipitated, showed a reaction rate two orders of magnitude higher than that of untreated cellulose, about the same magnitude as cornstarch. The alpha-cellulose when treated with a varying level of H2SO4 underwent an abrupt change in physical structure (fibrous form to gelatinous form) at about 65% H2SO4. The sudden shift of physical structure and reaction pattern in response to acid concentration and temperature indicates that the main factor causing the change in cellulose structure is disruption of hydrogen bonding. Finding effective means of disrupting hydrogen bonding before or during the hydrolysis reaction may lead to a novel biomass saccharification process.
Xiang
Qian
Q
Department of Chemical Engineering, 230 Ross Hall, Auburn University, Auburn, AL 36849, USA.
Lee
Y Y
YY
Pettersson
Pär O
PO
Torget
Robert W
RW
D002482:Cellulose / Q000737:chemistry* / Q000648:ultrastructure; D004187:Disaccharides / Q000737:chemistry; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007700:Kinetics; D008855:Microscopy, Electron, Scanning; D013464:Sulfuric Acids; D013816:Thermodynamics
D004187:Disaccharides; D013464:Sulfuric Acids; D002482:Cellulose; C033158:sulfuric acid