HIGH-RESOLUTION SOLID-STATE C-13 NMR-STUDIES OF AUSTRALIAN COALS

A detailed solid-state 13C NMR study on 29 Australian coals, varying in rank from semianthracite to brown coals, are reported. The experiments have been carried out at a high magnetic-field of 7.05T by using the standard techniques of CP/MAS/HPPD in conjunction with a TOSS pulse sequence. The results include the study of cross-polarization dynamics in the colas and dipolar-dephasing analyses of the samples. With the high-field spectrometer and the techniques used, various carbon types have been identified and the distribution of these carbon functionalities has been determined. Additional parameters related to aromatic structures, namely, the degree of substitution of aromatic rings and the average aromatic cluster size have been estimated. The variations in the structural parameters are discussed in view of the aromatic and aliphatic structures of the coals. © 1990.