Determination of aromatic hydrocarbon fraction in oil shale by 13C n.m.r. with magic-angle spinning

✍ Scribed by Henry A. Resing; Allen N. Garroway; Robert N. Hazlett

• Publisher: Elsevier Science
• Year: 1978
• Tongue: English
• Weight: 593 KB
• Volume: 57
• Category: Article
• ISSN: 0016-2361
• DOI: 10.1016/0016-2361(78)90152-7

✦ Synopsis

A method for estimation of aromatic content in oil shales is demonstrated. Magic-angle spinning at 2 kHz is shown to remove chemical shift anisotropy to a sufficient degree to resolve aromatic and aliphatic 13C n.m.r. spectral regions for a lithic oil shale specimen. The proton and carbon n.m.r. relaxation parameters are such as to allow room-temperature use of this proton-enhanced 13C n.m.r. technique as a quantitative analytical tool. Cross polarization times of a millisecond or less and experiment repetition periods of 0.5 s or less are optimum. The specimen examined is represented by an aromatic carbon fraction 0.264 It 0.007; this determination is quite insensitive to the protoncarbon cross polarization time. Spectra for kerogen, shale oil, and dawsonite are also presented. Dawsonite may interfere in the determination of the aromatic fraction.

Table 1 Mineral specimens Oil shalea Kerogen b Green River formation in area yielding 40 U.S. gallons crude oil per short ton of shale Prepared from shale rock located a few feet below the Mahogany Zone marker near the Bureau of Mines Demonstration Plant, Anvil Points, COIO.~ Paraho process shale oil Dawsonite (a) naturalC (b) syntheticd NahcoliteC Prepared from shale rock from the Naval Oil Shale Reserve near Anvil Points, COIO.~ Museum No. 127473 in Olduvai Gorge, Tanzaniag Method of Jackson, Huggins and Ampian' Museum No. 105809, Rifle, Colo.