An FTIR study of australian coals: Characterization of oxygen functional groups

The FTIR data in the oxygen-hydrogen stretching and carbonyl stretching regions for 28 Australian coals and their liquefaction products have been investigated. It was found that for the higher rank coals and asphaltenes, the absorbance at 3200 cm^-1 correlates with the atomic O/C values and the acidic oxygen contents as measured by a non-aqueous titration technique. The technique of least-squares curve fitting was applied to deconvolute the carbonyl stretching region. The results showed that for the higher rank coals there were relationships between the amount of carbonyl functional groups present, as measured from the band areas, and the coal O/C values. Most brown coals with a high oxygen content (O/C > 0.26) contain less guest material and have a lower concentration of carbonyl groups both as acids and esters than brown coals with a lower oxygen content. They have a higher non-acidic oxygen content, principally as ethers.