Infrared spectra of coal macerals separated from Bulgarian lignites

Abstract

The infrared spectra of the macerals resinite, humoresinite, textinite, ulminite, semifusinite and fusinite, separated from Bulgarian lignites, are discussed. Quantitative increment analysis is used. It has been established that the contents of the functional groups in the liptinite and huminite maceral groups are different, but the aromaticities are quite similar. The spectral characters and complexity are due to the different amount of lignincellulose tissue and resinite which entirely or partially fills the cell lumens of the wood. The infrared spectra of the inertinite maceral group have a simple pattern. In the semifusinite the absorption bands recorded are attributed to the low degree of oxidation and the large resinite content, respectively. The strong absorption of the fusinite is influenced by the higher content of condensed aromatic and hydroaromatic ring structures. The investigations indicate that the fusinite was formed during thermal destruction of the wood tissue, which proceeded at a high speed.