NMR INVESTIGATION OF LOW-RANK COAL LITHOTYPES PRETREATED WITH NAH

NaH pretreatment was applied to the low-rank coal lithotypes xylain, h umovitrain and humoclarain, with the aim of partial destruction of the coal structure. The treated lithotypes were fractionated according to their solubility in decalin, alkali solution, and tetrahydrofuran. Th e soluble fractions were analysed by H-1 and C-13 n.m.r. spectroscopy in solution. C-13 CP-MAS and TOSS n.m.r. spectroscopy were applied to solid-state fractions. Similar structural features were observed for t he decalin-soluble fractions, indicating that the different lithotypes contain considerable amounts of organic material similar in origin an d degree of chemical alteration. In humovitrain alkali- and tetrahydro furan-soluble and -insoluble fractions, altered lignin material was as sumed to be the basic constituent. The xylain tetrahydrofuran-soluble fraction is considered to contain mainly resinous material, while the insoluble part is suggested as having a lignin origin. The data for th e humoclarain soluble and insoluble fractions provide evidence for the significant role of lipids besides lignin in the formation of this li thotype. A cellulose component was also detected, though in small quan tity. A low degree of chemical alteration is assumed for the coal matt er of humoclarain.