Release of covalently-bound alkane biomarkers in high yields from kerogen via catalytic hydropyrolysis

Fixed-bed pyrolysis of kerogens at high hydrogen pressures (>10 MPa, hydropyrolysis) in the presence of a dispersed sulphided molybdenum catalyst gives rise to extremely high yields of dichloromethane (DCM)-soluble oil (>65%). To illustrate the potential of this approach, the yields and conformations of the hopanes, steranes and methyl steranes released from Goynuk oil shale (a type I kerogenf by hydropyrolysis after prior sequential extraction of the shale with DCM and pyridine and batchwise hydrogenation at 300 degrees C (cf 520 degrees C for hydropyrolysis) are reported here. The total yield of aliphatic hydrocarbons from hydropyrolysis represented ca 30% w/w of the kerogen's organic matter with yields of the C-29-C-32 17 beta(H), 21 beta(H)-hopanes being between three and ten times greater than those from DCM extraction and the milder hydrogenation treatment. The yields of the C-33-C-35 17 beta(H), 21 beta H)-hopanes, not found in the DCM extracts and only minor constituents in normal pyrolysis oil, were again typically at least three times higher than from hydrogenation.