New research from North Carolina State University provides molecular-level insights into how cellulose -- the most common organic compound on Earth and the main structural component of plant cell walls -- breaks down in wood to create "bio-oils" which can be refined into any number of useful products, including liquid transportation fuels to power a car or an airplane.
Using a supercomputer that can perform functions thousands of times faster than a standard desktop computer, NC State chemical and biomolecular engineer Dr. Phillip Westmoreland and doctoral student Vikram Seshadri calculate what's occurring at the molecular level when wood is rapidly heated to high temperatures in the absence of oxygen, a decomposition process known as pyrolysis.
The results, which could help spur more effective and efficient ways of converting farmed and waste wood into useful bio-oils, appear in a feature article on the cover of the Dec. 13 print edition of the Journal of Physical Chemistry A.
Much of the energy that can be extracted from wood exists in the cellulose found in cell walls. Cellulose is a stiff, rodlike substance consisting of chains of a specific type of a simple sugar called glucose. The paper describes a mechanism for how glucose decomposes when heated. The mechanism is somewhat surprising, Westmoreland says, because it reveals how water molecules and even the glucose itself can trigger this decomposition.
"The calculations in the paper show that although the decomposition products and rates differ in glucose and cellulose, the various elementary steps appear to be the same, but altered in their relative importance to each other," Westmoreland says.
Knowing the specifics of the decomposition process will allow researchers to make predictions about the ease of extracting energy from different types of wood from various soil types.
The researchers are now conducting experiments to verify their calculations.
The research was funded by the U.S. Department of Energy. The computations were performed on Pittsburgh Supercomputing Center computers.
- Vikram Seshadri, Phillip R. Westmoreland. Concerted Reactions and Mechanism of Glucose Pyrolysis and Implications for Cellulose Kinetics. The Journal of Physical Chemistry A, 2012; 116 (49): 11997 DOI: 10.1021/jp3085099
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