North Carolina State University’s chemical and biomolecular engineer Dr. Phillip Westmoreland and doctoral student Vikram Seshadri looked at the molecular level when wood is rapidly heated to high temperatures in the absence of oxygen, a decomposition process known as pyrolysis.
Much of the energy that can be extracted from wood exists in the cell wall cellulose, a stiff, rodlike substance consisting of chains of a specific type of a simple sugar called glucose. Cellulose is the most common organic compound on Earth and the main structural component of plant cell walls.
The team’s results which could help spur more effective and efficient ways of converting farmed and waste wood into useful bio-oils, appeared in a feature article and is on the cover of the Dec. 13 print edition of the Journal of Physical Chemistry A. The insight the team has gained is worth a look.
Using a supercomputer that can perform functions thousands of times faster than a standard desktop computer the team calculated what’s occurring at the molecular level when wood is rapidly heated to high temperatures in the absence of oxygen.
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.
Westmoreland said, “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.”
The paper’s title, Concerted Reactions and Mechanism of Glucose Pyrolysis and Implications for Cellulose Kinetics, reveals the relative complexity of the team’s efforts. An oversimplification could be the team followed the earlier work of Sanders et al. from 2003 in the Journal Anal. Appl. Pyrolysis, 2003, 66, 29–50.
From that starting point the team computed concerted transition states, elementary-reaction pathways, and rate coefficients for the concerted reaction of thermal decomposition of primarily the glucose and the related molecules. They look at and include the reactions for molecular ring opening and formation, ring contraction, retro-aldol condensation, keto–enol tautomerization, and dehydration.
It’s fuel for chemists and a wee bewildering for everyone else. The major news value is 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.
Westmoreland and Seshadri are now conducting experiments to verify their calculations. Odds are the calculations will be on the marks.
The learning curve that the team will be proving up should take wood producers and processors closer to the economic bottom of costs in the search for efficiency meaning less investment, less land and lower operating costs. For now much of the pyrolysis effort is simply flying blind into raw materials processing on to the products.
Its not a breakthrough, rather the team is doing the hard methodical work to make the tools to get to the breakthroughs much sooner and faster. Its “Manna From Heaven” for the pyrolysis enthusiasts.
This is the hard work – getting through it deserves and has earned a journal cover.