Heterogeneous aspects of acid hydrolysis of α-cellulose |
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Authors: | Qian Xiang Y Y Lee Pär O Pettersson Robert W Torget |
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Institution: | 1. Department of Chemical Engineering, Auburn University, 230 Ross Hall, 36849, Auburn, AL 2. Mid Sweden University, 891 18, ?rnsk?ldsvik, Sweden 3. National Renewable Energy Laboratory, 1617 Cole Blvd., 80401, Golden, CO
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Abstract: | Hydrolysis of α-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, α-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 α-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. |
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Keywords: | Acid hydrolysis cellulose hydrogen bonding kinetics crystallinity |
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