Pyrolysis of Maritsa Iztok lignite lithotypes: geochemical implication

Pyrolysis coupled “off-line” with thermal desorption gas chromatography–mass spectrometry (TD-GC/MS) instrument for flue gas analysis is used to specify qualitatively/quantitatively organic functionalities in “Maritsa-Iztok” lignite lithotypes thermal decomposed in the range 250–900 °C. The aim of the study is to specify organic volatiles and to assign identified components to the lignocellulose biomass building blocks of coal forming vegetation. In pyrolysates the total amounts of the analyzed organics, expressed in mg/g TOC, amount up to 58.14 for liptain, 21–37 for humoclarain and xylain, and the lowest values are determined for humovitrain, 12. The samples immaturity reflects in high diversity of phenols, methoxy phenols (only guaiacyl structures), furans, etc. maximizing at xylain lithotype, 68% of the total analyzed amount. Carbohydrate degradation products, i.e. furaldehydes, 2-cyclopenten-1-ones, etc. are identified as well. In lithotypes studied, coal biomarkers as n-alkene/n-alkanes, sesqui-, di-, polar diterpenoids and hopenes/hopanes, are present in different proportions.