(600az) Revealing Cellulose Pyrolysis Chemistry

Title: Revealing Cellulose Pyrolysis
Chemistry

Authors: Alex D. Paulsen, Matthew S. Mettler,
Dionisios G. Vlachos & Paul J. Dauenhauer

Abstract: Fast pyrolysis converts solid biomass to
a liquid bio-oil which can be further upgraded to fuels or chemicals. This
multi-step process consists of solid, liquid, gas and catalytic chemistries
which must be studied independently in order to maximize insight. This work
develops a kinetically-limited experimental technique for studying biomass
pyrolysis and shows that glucose and cellodextrins do not behave similarly to
cellulose while α-cyclodextrin does. The effect of
temperature on cellulose pyrolysis products is also examined.

Additionally, we investigate
secondary pyrolysis pathways within molten biomass using isotopically-labeled
starting materials. Through
the use of ¹³C-labeled sugars, we show that levoglucosan breaks down
within the molten phase to form pyrans, light (C₂-C₃)
oxygenates, and other anhydrosugars. The mechanisms of these reactions is
unknown; however, we have shown using deuterated carbohydrates that
levoglucosan decomposition products exhibit a distinct relationship between
extent of elimination reactions and hydrogen exchange during reaction.  This
demonstrates that hydrogen, which likely serves as a Brønsted catalyst within
molten cellulose, plays a role in the decomposition of levoglucosan during
cellulose pyrolysis.