NMR of petroleum cokes I: Relaxation studies and quantitative analysis of hydrogen by magnetic resonance

• Published in: Carbon (New York) Vol. 32; no. 1; pp. 31 - 40
• Main Authors: Michel, D., Pruski, M., Gerstein, B.C.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 1994; Elsevier Science
• Subjects: 1H NMR; Applied sciences; Constitution and properties of crude oils, shale oils, natural gas and bitumens. Analysis and characteristics; Crude oil, natural gas and petroleum products; Energy; ESR; Exact sciences and technology; Fuels; nuclear relaxation; Petroleum coke; spin counting; spin counting; 1H NMR; nuclear relaxation; ESR; Petroleum coke; Spin relaxation; Hydrogen; Nuclear relaxation; Magnetic resonance; EPR spectrometry; NMR spectrometry; Experimental study
• ISSN: 0008-6223; 1873-3891
• DOI: 10.1016/0008-6223(94)90006-X

A set of 15 petroleum cokes produced by delayed coking in a Mobil laboratory coker has been studied using solid state 1H NMR. From solid echo and free induction measurements, the concentrations of hydrogen as well as inter- and intramolecular second moments due to dipolar proton-proton interactions were measured. Electron spin resonance (ESR) was used to determine the concentrations and nature of paramagnetic sites. The longitudinal relaxation times in the laboratory and rotating frames were measured and the relaxation mechanisms discussed. Relaxation parameters were found to be derived from two-exponential fits of experimental data. These parameters were not related to structural parameters of cokes obtained in subsequent studies by high resolution NMR of 1H and 13C.