| Large polycyclic aromatic nitrogen containing asphaltene model compounds, with molecular weights from 535 to 702 g/mol, were catalytically hydrogenated and hydrodenitrogenated in the presence of a commercial NiMo/γAl2O3 catalyst in a stainless steel batch reactor at 370 °C and 17.9 MPa total pressure for 1 h. The patterns and pathways of hydrogenation of two families of model compounds were investigated: alkyl-bridged pyrenes linked to a pyridine centre ring and substituted cholestane—benzoquinoline compounds. Analysis of reaction products by matrix assisted laser desorption ionization—mass spectrometry, high performance liquid chromatography, and gas chromatography demonstrated that for the pyrene/pyridine family there was a strong preference for hydrogenation of the bridged pyrene groups compared to the centre pyridinic ring. For the cholestane family, no cracking or hydrodenitrogenation reactions occurred. Results imply that hydrotreatment of similar large nitrogen asphaltene compounds are dominated by reactions other than hydrodenitrogenation. |
