1. Insights into molecular structural changes of kerogen during thermal evolution investigated by advanced solid-state NMR spectroscopy Jingdong Mao Department of Chemistry and Biochemistry, Old Dominion University, VA, 23508
Based on two-dimensional 1H-13C heteronuclear NMR, the spatial proximity of different functional groups in kerogen and its changes with increasing thermal maturity was examined.
With increasing thermal maturity, the 1H slices extracted at a chemical 13C shift of 29 ppm are initially limited to one band that is primarily due to CH2 groups.
However, the slices of kerogens and IL-3 exhibit an emerging 1H shoulder above 5 ppm and thus indicate that CH2 groups are beginning to “see” the proximity of aromatic protons. Apparently aliphatic -(CH2)n- chains tend to get shortened and connected to aromatic moieties with increasing thermal maturity.
Conversely, the alkyl 1H peaks at 2 ppm in slices extracted at a 13C chemical shift at ~127 ppm from the HETCOR spectra show that aromatic rings are abundantly connected with alkyl groups.