THERMAL ANALYSIS AND PYROLYSIS-GAS CHROMATOGRAPHY/MASS SPECTROMETRY OF FOSSIL WOOD FROM OF BГњKKГЃBRГЃNY, HUNGARY
O. A. Shapchenkova1, S. R. Loskutov1, M. A. Plyashechnik1, Z. PГЎsztory2
1V. N. Sukachev Institute of Forest, Russian Academy of Science, Siberian Branch Federal Research Center Krasnoyarsk Scientific Center, Russian Academy of Sciences, Siberian Branch, Krasnoyarsk, Russian Federation
2University of Sopron, Sopron, Hungary
Keywords: thermogravimetry, differential scanning calorimetry, analytical pyrolysis, evaluation of chemical composition alterations of fossil wood, bald cypress (Taxodium distichum (L.) Rich.), Western Hungary
Abstract
Fossil wood that is ca 7 million years old from Bükkábrány (Hungary) was analyzed by thermogravimetry (TG), differential scanning calorimetry (DSC) and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) to evaluate alterations of its chemical composition. A wood sample of bald cypress ( Taxodium distichum (L.) Rich.) from West Hungary was taken as a reference. The fossil wood was characterized by higher contents of total carbon (58.05 %) and total nitrogen (0.44 %) compared to recent wood. TG of fossil wood showed a high heterogeneity of wood substance, significant loss of polysaccharides and enrichment by lignin including more thermally stable components (> 500 °C). The enthalpy change (∆H) of combustion (thermo-oxidation) for fossil wood was significantly higher than for recent wood (-18.17 kJ/g vs. -11.41 kJ/g). Py-GC/MS analysis of fossil wood showed a significant depletion of polysaccharide pyrolysis products and an increase in lignin pyrolysis products compared to recent wood. The pyrolytic H/L ratio indicates a preferential loss of polysaccharides in fossil wood. Polysaccharide pyrolysis products were rare and represented mainly by levoglucosan. Lignin also underwent substantial changes. A dramatic decrease in monomers, an increase in short side chain compounds and the presence of demethylated/demethoxylated compounds in the composition of lignin pyrolysis products are indicative of lignin alteration (degradation). Moreover, a high abundance of styrene, cresols, phenol and phenolic compounds was observed.
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