3. FOOD ChEMISTRy & bIOTEChNOLOGy 3.1. Lectures

Chem. Listy, 102, s265–s1311 (2008) Food Chemistry & Biotechnology
P72 ThERMOGRAVIMETRIC ANALySIS OF
LIQuID PyROLySIS PRODuCTS OF wOODy
bIOMASS
RADOSLAV MIKULáŠIK, JAnA KOSInKOVá, ALEŠ
HáZ, SOňA FIGEDYOVá and IGOR ŠURInA
Department of Chemical Technology of Wood, Pulp and
Paper, Faculty of Chemical and Food Technology, Slovak
Technical Univerzity Radlinského 9, 812 37 Bratislava, Slovak
Republic,
Radoslav.Mikulasik@stuba.sk
Introduction
Thermal analysis (TA) represents a set of methods, used
to study the changes of investigated material by measuring
some physical properties as a function of temperature.
nowadays, several thermoanalytical methods are used,
differing in monitored physical property (mass, volume,
length, magnetic susceptibility, temperature difference
between sample and reference sample), etc.
In thermogravimetric analysis (TGA), mass changes of
sample are determined as a function of temperature.
Data obtained from TG measurements are used to
investigate thermal stability of substances, determination of
relative volatility and determination of other physical and
chemical parameters. First derivative of TGA curve according
to temperature is denoted as DTGA or DrTGA and represents
the rate of reaction.
TGA is used very frequently to study thermal behavior
of different kinds of biomass (in inert or oxidative atmospheres),
mainly agricultural crops or their residues 1 , woody
wastes 2 , some fossil fuels – coal and blend fuels (biomass/
coal) 3,4 .
Pyrolysis of plant or woody materials generates solids,
liquids and gaseous fuels or products. Their composition
depends on the pyrolysis process conditions. 5–8
Thermal behaviour of liquid and solid pyrolysis products
– bio-oil and wood coal – usable as fuels or for energetic
purposes – can be studied by means of thermoanalytical
methods. Experimental part of this work is focus on TGA,
which was used for study of thermal behaviour and thermal
stability of fractions of bio-oil in inert atmosphere.
Experimental
M a t e r i a l s
Bio-oil fractions originating at industrial pyrolysis of
beech wood – pyrolysis condensate (PC), pyro-oil (PO), and
wood tar (WT) were suplied from SLZ Chémia, Slovakia.
M e t h o d s a n d I n s t r u m e n t s
Thermogravimetric analysis (TGA) was performed on
a Mettler Thermoanalyzer 2, in inert gas atmosphere (nitrogen).
Conditions: flow rate: 60 ml min –1 , temperature program
was 10 °C min –1 from 25 to 600 °C, analysis time 60 min, and
sample amount was ~ 20 mg.
s730
Results
As can be seen from TGA results (Fig. 1.) of pyrolysis
condensate (PC), temperature rise up to ~ 120 ºC resulted in
more than 90 % weight loss. PC is formed of a mixture of
compounds which distillated with the highest rate at 97 ºC.
This fraction of bio-oil according to TGA curve contains
mainly volatile organic compound (VOC) and water. VOC is
defined as a compound which has boiling point equal or less
than 250 °C at pressure 101.3 kPa 9 .
Fig. 1. TG analysis of pyrolysis condensate
The results of TGA analysis of pyro-oil (PO) document
(Fig. 2.) that PO still contains VOC (6 %), but their amount is
much lower than that present in the fraction of PC. Increasing
the temperature to ~ 410 ºC leads to ~ 93 % weight loss and
so the most part of PO distilled off or is thermally decomposed.
Fig. 2. TG analysis of pyro-oil
The results of TGA analysis of wood tar (Fig. 3.) led
to a conclusion that reaching temperature ~ 400 ºC, 75 % of
wood tar fraction (WT) underwent decomposition.
This fraction contains also thermally stable compounds
as evidenced by residual more than 20 % amount at 600 ºC.
The individual phases of the thermal decomposition
or degradation – namely I. dehydratation and volatilisation,
II. active pyrolysis and III. passive pyrolysis 10 were analysed.