Pyrolysis of Potassium-Doped Wood at the Centimeter
and Submillimeter Scales
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Abstract
The
effect of potassium additives on pyrolysis of poplar was investigated
at 427 °C, both at the submillimeter scale, through thermogravimetric
analysis (TGA), and at the centimeter scale, through pyrolysis of
wood cylinders in a turbulent reactor. Internal temperatures and time-resolved
rates of production of gases and light volatiles were measured in
the centimeter-scale study. The potassium level in the samples was
varied through vacuum treatment with distilled water or solutions
of KCl or K<sub>2</sub>CO<sub>3</sub>, resulting in potassium levels
of approximately 100, 4500, and 7000 ppm (dry, mass basis). At the
centimeter scale, potassium addition had a dramatic effect on conversion
time and on the magnitude of exothermic temperature excursions, as
well as a significant effect on the yields of gases and light volatiles.
Consistent with the literature, submillimeter-scale TGA experiments
with external temperature control also indicated a catalytic effect
of the potassium additives, with K<sub>2</sub>CO<sub>3</sub> more
effective than KCl in promoting pyrolysis and char formation
