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 kerogen) by hydropyrolysis after prior sequential extraction of the shale with DCM and pyridine and batchwise hydrogenation at 300°C (cf 520°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 C29–C32 17β(H), 21β(H)-hopanes being between three and ten times greater than those from DCM extraction and the milder hydrogenation treatment. The yields of the C33–C35 17β(H), 21β(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.