Siberian Federal University

Processes of thermal decomposition of lignin isolated from aspen wood by different methods and their thermal dissolution with ethanol and isopropanol at 400 °C were studied. According to tandem thermogravimetry data two maximum of thermal decomposition rate of the lignin samples were recorded in the temperature range between 250-311 °C and 364-407 °C. Taking into account the composition of gaseous products formed, it was suggested that the first of them corresponds to cleavage of relatively thermal unstable oxygen containing chemical bonds, while the second accords to a destruction of the basic structure of lignin with the rupture both of oxygen containing bonds and C-C bonds. The first stage had the dominant influence (weight loss 16 wt. %) in the decomposition of Organosolv lignin. It was established that the method of lignin isolation from aspen wood had a significant effect on its reactions ability in the process of thermal dissolution in alcohols. The maximum degree of conversion was observed for the Organosolv lignin (57.2 - 57.6 wt.%). The highest yield of liquid products boiling up to 180 °C (26.0 - 28.5 wt.%) was obtained with Alkali lignin.