The material balance of carbonization products (wood-gas, wood-vinegar, woo
d-tar and charcoal) prepared from the sapwood and the heartwood of Sugi (Cr
yptomerica japonica D. Don) at various temperatures was determined. The evo
lution of both carbon monoxide and carbon dioxide mainly occurred at the ca
rbonization temperature below 600 degrees C and that of hydrogen and methan
e at 600-800 degrees C. Total yield of the wood-vinegar and the wood-tar wa
s almost constant at 500-800 degrees C. On the other hand, the yield of the
charcoal decreased because of the evolution of the wood gas with an increa
se in carbonization temperature.
The wood-vinegars prepared at the temperature over 400 degrees C were found
to consist of carboxylic acids such as acetic acid and propionic acid, met
hanol, acetone, furans, alkylphenols, guaiacols, cyclotene and maltol by ca
pillary gas chromatography. Since the constituent varieties and contents of
the wood-vinegars prepared at both 400 degrees C and 800 degrees C were ve
ry similar each other, the wood-vinegar of Sugi wood chiefly produced below
400 degrees C.
FT-IR spectra of the charcoals showed the generation of carbonyl and olefin
groups at 300-400 degrees C and then the formation of aromatic rings along
with the disappearance of carbonyl groups over 600 degrees C. The producti
on of radical species in the charcoals carbonized at 300-600 degrees C was
observed by ESR, on the contrary, the charcoals carbonized over 700 degrees
C were inactive. The specific surface area and the pore volume of the char
coal of Sugi sapwood increased with an increase in carbonization temperatur
e. The pH of charcoal-dispersed aqueous solution increased with an increase
in carbonization temperature. The high adsorptive activity of the charcoal
carbonized at 400 degrees C for ammonia gas and that at 800 degrees C for
hydrogen sulfide gas seemed to be dependent on acidic and basic properties
of the charcoals, respectively.