HYDROPYROLYSIS - A VERSATILE TECHNIQUE FOR SOLID-FUEL LIQUEFACTION, SULFUR SPECIATION AND BIOMARKER RELEASE

High oil yields (ca. 60% both daf and carbon basis) with relatively lo w hydrocarbon gas yields can be achieved for coals and oil shales in f ixed-bed pyrolysis at high hydrogen pressure (hydropyrolysis, 15 MPa) with relatively fast heating and a suitable dispersed catalyst, such a s sulphided Mo or Fe. This article reviews the application of hydropyr olysis to biomass and its adaptation as an analytical technique to spe cify organic sulphur forms and to release covalently-bound biomarker h ydrocarbons for coals and petroleum source rocks. Results for cellulos e, eucalyptus wood and sugar cane bagasse demonstrate the potential of hydropyrolysis for producing bio-oils with much lower oxygen contents than by traditional pyrolysis processes. The inherent drawbacks with temperature programmed reduction (TPR) for specifying the organic sulp hur forms in sedimentary organic matter in that (i) thiophenic sulphur has largely been undectable and (ii) sulphides interconvert readily i nto thiophenes have been overcome by the use of the well-swept fixed-b ed hydropyrolysis reactor operating at 15 MPa. The application of high pressure TPR to pyrite-free bituminous coal and a type-IIS kerogen is described. To illustrate the ability of hydropyrolysis to release cov alently-bound biomarker hydrocarbons from sedimentary organic matter, the yields and conformations of the hopanes and steranes released from a type I kerogen are presented. (C) 1997 Elsevier Science B.V.