Study of Low Rank Greek Coals Using FTIR Spectroscopy

Fourier transform infrared (FTIR) spectra of lignite and humic clay samples, collected from 2 boreholes located at Apofysis-Amynteo lignite deposit, NW Greece, as well as their insoluble organic matter, obtained by Soxhlet extraction with dichloromethane, were recorded between 400 and 4,800 cm−1. In the same way, FTIR spectroscopy was used to study a xylite sample from Vevi xylite basin (north of Apofysis-Amynteo lignite deposit) and its chars, which are the solid products of pyrolysis, at 3 final fixed temperatures: 400°C, 600°C, and 800°C. In the Apofysis-Amynteo samples, oxygen-containing structures were observed in the 1,800–1,000 cm−1 zone, aliphatic hydrogen in the 2,950–2,700 cm−1 zone, aromatic out-of-plane structures in the 900–670 cm−1 zone, and hydroxyl groups in the 3,400–3,600 cm−1 zone. A great abundance of C=O and C–O–R structures in the 1,800–1,000 cm−1 region were noticed, while clay and silicate minerals were identified in the 400–600 cm−1 and 3,600–3,800 cm−1 zones. In the IR spectra of the initial xylite sample BEX, the major quantity of H2O is at a wave number of 3,400 cm−1. A strong peak at 1,032 cm−1 in the xylite sample is evidence of the presence of phenolic and alcoholic C–O bonds as well as C–O–C bonds with aliphatic or aromatic carbons. The 800°C char, at the same wave number, presents only a weak peak.