THERMAL ALTERATION OF UNBOUND BIOMARKERS IN LOW RANK COALS DURING HYDROUS PYROLYSIS SIMULATING EARLY COALIFICATION

Abstract

Publisher Summary This chapter explores thermal alteration of unbound biomarkers in low-rank coals during hydrous pyrolysis simulating early coalification. In a study described in the chapter, a medium-light lithotype sample of a Victorian brown coal, taken from core R327 in the Rosedale field at the 171.6 m depth, was used. Undried raw coal with 10 ml of washed, deionized CHCl3 and distilled water were placed in a stainless steel reaction vessel of 70 ml capacity, were purged with N2 gas, and were then closed. The reactor was rapidly heated to the required temperature and held there for 72 h. After cooling and opening, the contents were removed, and the reactor was washed with CHCl3/CH3OH. The washings were concentrated under a gentle nitrogen flow, and the concentrate was recombined with the solid residue. The whole freeze was dried and ground to <100 mesh. Thermal desorption/gas chromatography analysis shows that pentacyclic triterpenoids are the most abundant biomarkers in this coal and that the fully saturated hydrocarbons have hopanoid skeletons.