ELECTRON-MICROPROBE AND MICRO-FTIR ANALYSES APPLIED TO MACERAL CHEMISTRY

Combined electron microprobe and reflected micro-FTIR analysis permit maceral scale chemical characterization of coal and organic matter dispersed in rocks. Elemental composition derived from electron microprobe compares closely with the composition of the same samples analyzed following ASTM procedures. Reflected micro-FTIR yields spectra comparable to those obtained in transmission micro-FTIR mode and maceral concentrates analyzed using KBr pellet techniques. The application of the electron microprobe and reflected micro-FTIR techniques is demonstrated by analyses of macerals from a suite of coal of varying rank. With increasing rank there is a progressive decrease in elemental O and increase in C content. The change in functional groups associated with increase in maturation is most conspicuous in the decrease in intensity of absorbance of aliphatic stretching bands (2800-3000 cm(-1)), and carboxyl/carbonyl band (1710 cm(-1)) and an increase in the 1600 cm(-1) aromatic band. Elemental composition together with reflectance analyses suggest that liptinite and vitrinite attain a similar coalification path at about 88.5% C and reflectance of 1.25% and semifusinite merges with the vitrinite/liptinite coalification path at 89.5% C and a reflectance values of about 1.8-2.0%.