DYNAMIC AND STRUCTURAL PARAMETERS OF COAL AND COAL-DERIVED PRODUCTS

Abstract

In this study a brown coal and a bituminous coal were subjected to different treatments. Firstly, both raw coals were subjected to a noncatalytic liquefaction. Secondly, a chloroform and a pyridine extraction was carried out for both coal samples. The raw coals, the solvent refined coals and extraction residues were investigated by C-13 CP/MAS NMR. Variable contact time, spin-spin relaxation times of protons, and proton dephasing experiments were performed. Average structural parameters were derived from the results of variable contact time studies in combination with elemental analysis data. In nearly all cases, the spin-spin relaxation behavior of aromatic and aliphatic protons can be closely fitted by the sum of a Gaussian and a Lorentzian function, corresponding to rigid and mobile molecular components. The results of these relaxation measurements were compared with those of previous studies and discussed in terms of molecular structure. The characterization of changes in the amount and in the mobility of the two components, after the different treatments, offers a new insight into the molecular structure of coal.