Internal structure of vitrinite and sporinite in the view of micro-FTIR spectroscopy using the example of coal from the seam 405 of the Upper-Silesian Coal Basin (USCB)

The aim of the study was to compare the internal structure of vitrinite and sporinite obtained from coal from the seam 405. The examinations were performed with the use of infrared spectroscopy in the micro-area (micro-FTIR). Studies have shown that vitrinite is characterized by lower content of aliphatic components and greater content of aromatic components than sporinite. Sporinite is characterized by longer and less branched aliphatic chains than vitrinite. It was found that vitrinite internal structure is characterized by a greater relative content of aromatic than aliphatic components. The degree of condensation of aromatic rings in structure of vitrinite increases, when the coal rank rises. Studies have shown that the transformation of the vitrinite internal structure towards a structure characterized by a greater degree condensation of aromatic components proceeds at the cost of restructuring the aliphatic groups and is related to the restructuring of the aromatic systems. The structure of sporinite is characterized by a greater participation of aliphatic bonds as compared to aromatic bonds. The relative content of the aliphatic components decreases together with increase of aromatic hydrogen functional group CH_ar content in the internal structure of sporinite when the coal rank rises. The aliphatic bonds in the sporinite are subject to restructuring. The aliphatic chains are getting increasingly shorter.