Application of TG–FTIR to the determination of organic oxygen and its speciation in the Argonne premium coal samples

During rapid pyrolysis of coal, TG–FTIR (thermogravimetry – Fourier transform infrared) technique can be effectively used to simultaneously detect and measure the three main O-containing gases, namely H2O, CO and CO2. Their sum corresponds to the quantitative amount of oxygen in the coal and is, in general, inherently more accurate than the ‘by-difference’ values.In this paper, we first attempt to relate the ‘by-difference’ values for %O reported for the Argonne premium coal samples (lignite to bituminous rank) (Argonne Users Handbook) to those determined from a TG–FTIR examination of the pyrolysis gases evolved. Another objective of the work is to relate the pyrolysis gases (H2O, CO and CO2) evolved to oxygen-containing functional groups found in coals as well as the evolution of these functional groups as a function of rank. Correlations are also developed between the TG–FTIR oxygen values and other parameters determined for the Argonne Premium Coals. In particular, comparisons of our results using TG–FTIR with analyses carried out by other workers on functional group analysis of acidic groups are considered.