Chapter 6 - CHEMICAL STRUCTURE OF VICTORIAN BROWN COAL

Abstract

Publisher Summary This chapter describes the chemical structure of Victorian brown coal. Victorian brown coals represent one of the purest and most extensive concentrations of organic matter anywhere in the world with ash yields generally less than 2%. These coals typically contain 69.6% carbon, 5.0% hydrogen, 24.6% oxygen, 0.5% nitrogen, and 0.3% sulfur on a dry mineral and nonmineral-inorganic free basis. A significant amount of research interest has been directed towards the structural elucidation of Victorian brown coals. Victorian brown coals are structurally complex and heterogeneous because of their detrital origin and early stage of coalification. These coals are derived from demethylated dehydrated lignin monomers intermixed with lipid material, such as polymethylene long chain acids, esters, and triterpenoids of both higher plant and microbial origin. The presence of cellulose remnants reflects the early stage of coalification. The use of controlled degradation techniques has helped confirm the structural characteristics of Victorian brown coals as separately indicated by spectroscopic techniques. The variation in environments of deposition and decomposition, which occurred during the formation of Victorian brown coal deposits, led to significant variations in properties and structure, which further contribute to the coal's heterogeneity.