Thermal analysis and pyrolysis – gas chromatography/mass spectrometry of fossil wood from the locality of Bükkábrány, Hungary

Autor: O. A. Shapchenkova, S. R. Loskutov, M. A. Plyashechnik, Z. Pásztory
Jazyk: English<br />Russian
Rok vydání: 2022
Předmět:
Zdroj: Сибирский лесной журнал, Vol 9, Iss 5, Pp 56-69 (2022)
Druh dokumentu: article
ISSN: 2311-1410
2312-2099
DOI: 10.15372/SJFS20220505
Popis: 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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