N.m.r. and i.r. spectroscopy as well as fluorescence microscopy are applied to characterize hydrogenation residues of lignite lithotypes. The combination of spectroscopic and microscopic techniques allows a detailed description to be given of coal decomposition during the liquefaction process under several conditions. In particular, different decomposition steps in the coal network can be detected by n.m.r. and i.r. spectroscopy. A quantitative component analysis of the residues is performed using fluorescence microscopy. A new kind of residue constituent is detected indicating mild hydrogenation conditions for lignites. Furthermore, the conversion of the lignite macerals under different hydrogenation conditions is studied to obtain information on the formation of typical residue constituents. The techniques used complement each other and conclusions can be drawn about the hydrogenation process on lignite lithotypes.

High resolution 1H n.m.r. measurements combining the MREV-8 multiple pulse sequence and magic angle spinning have been carried out to estimate aliphatic and aromatic portions of protons in a soft brown coal. Contrary to the situation in bituminous coals, it is shown that there is a signal from remaining water even in carefully dried samples of brown coals. Two different line deconvolution strategies are applied to recalculate the real aromaticity value fαH.