3. FOOD ChEMISTRy & bIOTEChNOLOGy 3.1. Lectures

Chem. Listy, 102, s265–s1311 (2008) Food Chemistry & Biotechnology
Fig. 3. TG analysis of wood tar
Fig. 4. shows comparison of TGA curves of fractions of
bio-oil. It is obvious from this comparison that the least stable
fracion is PC, followed by PO and ending with WT.
Fig. 4. Comparison of TG analysis of bio-oil fractions at the
same conditions
Temperatures and weight losses for individual stages are
listed in Table I.
Table II indicates total weight losses for individual fraction
of bio-oil and corresponding decomposition temperatures
at which the maximum weight loss per minute occurs.
Data in tables for individual stages differ because every
fraction contains other compounds and in different quantitative
amounts.
Table I
Decomposition stages of bio-oil fractions and weight loss
Stage I. II. III.
T [°C] 25–130 130–410 410–600
Sample [mg] [%] [mg] [%] [mg] [%]
PC 18.80 90.8 0.91 4.4 0.26 1.3
PO 1.29 6.3 16.89 82.8 0.74 3.6
WT 2.29 11.2 12.80 62.4 0.89 4.3
s731
PC contains mainly water, VOC and hydrocarbons with
short chains. PO contains hydrocarbons with longer chains,
benzene and phenolic structures. WT is composed mainly
of condensed aromatic substances, benzene and phenolic
structures.
Table II
Total weight loss of bio-oil fractions and decomposition temperature
at max. weight loss
Sample Weight [mg] Loss [mg] Loss [%] t max [°C]
PC 20.7 19.963 96.4 97.1
PO 20.4 18.927 92.8 241.3
WT 20.5 15.953 77.8 207.9
Conclusions
In this work, we investigated three liquid fractions of
bio-oil generated in process of woody biomass pyrolysis
beechen wood.
TGA measurements indicated different composition of
individal fraction of bio-oil.
Pyrolysis condensate contains substantially volatile compounds
(VOC) and water than pyro-oil and wood tar. Pyro-oil
contains more VOC than wood tar, which is confirmed by
total weight losses of these fractions. Pyrolysis condensate
has total weight loss 96.4 %, pyro-oil 92.8 % and wood tar
77.8. So the residue of wood tar is highest at 600 °C.
At all fractions it is possible to deduce from TGA curves
that if temperature increases gradually, then distillation of
volatile compounds and their exothermal decomposition occur.
Distillation and decomposition process proceed in different
temperature intervals and weight losses at these intervals
are different for individual fractions, which means that each
fraction contains different substances with different ratio.
Based on TGA results it can be concluded that the least
thermal stability has fraction of pyrolysis condensate, followed
by pyro-oil and, finally, the most stable was wood tar.
We thank Slovak Grant Agency (Project VEGA
1/3567/06) for its financial support.
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