Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5420959 | Solid State Nuclear Magnetic Resonance | 2006 | 10 Pages |
Abstract
Five type II kerogens, shown by elemental analysis and Rock-Eval pyrolysis to represent a gradient of thermal maturity, were further characterized using a range of solid-state 13C NMR spectroscopic techniques. 13C cross polarization (CP) NMR spectra of the kerogens confirmed the well-established pattern of increasing aromaticity with increasing thermal maturity. Spin counting showed that CP observability was around 50% for the immature kerogens, and only 14-25% for the mature kerogens. Spin counting also showed that the direct polarization (DP) observabilities were >80% for all but one of the kerogens. Despite the large differences in observability between the two techniques, aromaticities derived from corresponding CP and DP spectra differed by only 1-15%. The RESTORE technique showed that the low CP observability of the immature kerogens was due mostly to rapid T1ÏH relaxation, whereas both rapid T1ÏH relaxation and slow polarization transfer contributed to the low CP observability of the mature kerogens.
Related Topics
Physical Sciences and Engineering
Chemistry
Physical and Theoretical Chemistry
Authors
Ronald J. Smernik, Lorenz Schwark, Michael W.I. Schmidt,