EAGER: Fundamental Study on Decrystalization of Cellulose for High-Yield Saccharification of Biomass

Auburn University, Auburn AL

Investigators

Abstract

Abstract: PI: Lee, Y. Y Proposal Number: 1348797 Institution: Auburn University Title: Fundamental Study on Decrystalization of Cellulose for High-Yield Saccharification of Biomass This project will develop a high-yield acid-catalyzed hydrolysis of biomass where the hydrolysis reaction is carried out under the conditions where decrystallization occurs prior to or concurrently with hydrolysis. This investigation will focus on the fundamental aspects of the decrystallization process using a stopped-flow micro reactor system designed to measure the extent of decrystallization by instantaneous detection of temperature change. With proper choice of reaction conditions extending to the region previously unexplored, this process can attain high sugar yield, with acid input much lower than that of the conventional ?concentrated sulfuric acid process?. The main resistance of acid hydrolysis of cellulose exists in the rigid crystalline structure which is held by tightly arranged hydrogen bonds. A method will be established to detect sulfuric acid induced decrystallization by instantaneous tracing of the temperature change caused by cleavage of hydrogen bonds. This method relies on using a modified ?Stopped-Flow? micro-reactor assembly capable of accurately tracing the temperature change in a fast reacting system. Using this method, the following hypotheses regarding decrystallization of cellulose will be proven or reaffirmed: (1) Decrystallization of cellulose behaves as a phase-change in that it occurs at a precise point in temperature (critical temperature) for a given acid concentration; (2) There are infinitely many decrystallization points, forming a unique correlation curve in the temperature vs. acid concentration plane; (3) Within the zone above the curve, decrystallization of cellulose occurs prior to hydrolysis, promoting rapid hydrolysis and high yield, whereas within the zone below the curve, decrystallization does not occur resulting poor sugar yields. This unique relationship curve will be determined for Avicel (micro-crystalline cellulose) and for pretreated hemicellulose-free corn stover. The results of this work will provide scientific and technical information needed for improvement of the current thermo-chemical biomass processing technology. A number of companies are developing commercial-scale processes on the basis of acid catalyzed biomass hydrolysis. The need for cheap sugars is ever increasing as the number of useful products derived from the sugar is fast growing. This investigation will provide better understanding on recalcitrance of cellulosic biomass induced by the crystalline structure, how it affects the hydrolysis, more importantly how the crystallinity can be reduced or removed. The fundamental knowledge to be gained by this work will find broad applications in production of fuels and other useful chemicals from renewable resources. The information along these lines can also be used as a tool to refine the process to make low-crystalline or nano-crystalline cellulose, which may be intermediates on the way to fully decrystallized cellulose.