CLOSE CORRESPONDENCE BETWEEN CARBON SKELETAL PARAMETERS OF KEROGENS AND THEIR HYDROPYROLYSIS OILS

Fixed-bed hydropyrolysis of petroleum source rocks and low-rank coals at pressures of ca. 15 MPa in the presence of a dispersed sulfided mol ybdenum catalyst gives rise to extremely high oil (dichloromethane-sol uble) yields (>60%) with overall conversions of the organic matter typ ically being greater than 90%. To ascertain whether hydropyrolysis oil s are representative structurally of their parent kerogens, carbon ske letal parameters derived from their solution state C-13 NMR spectra ha ve been compared with those from the quantitative solid state C-13 NMR analysis conducted using the single pulse excitation (SPE) technique on type I, II, and III kerogens. Indeed, when the latter values are co rrected for carboxyl/carbonyl carbons, both the carbon aromaticities a nd long alkyl chain contents of the hydropyrolysis oils and the parent kerogens investigated, within experimental error, are similar. This i ndicates that catalytic hydropyrolysis does not involve a significant change in aromaticity, unlike in normal pyrolysis where the extent of aromatization for type I and II kerogens is considerable. For the hydr ogenation and dehydrogenation that do occur, the extents of reaction m ust be fairly similar to keep the overall aromaticity constant.