NMR OF PETROLEUM COKES .1. RELAXATION STUDIES AND QUANTITATIVE-ANALYSIS OF HYDROGEN BY MAGNETIC-RESONANCE

A set of 15 petroleum cokes produced by delayed coking in a Mobil labo ratory coker has been studied using solid state H-1 NMR. From solid ec ho 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 fram es were measured and the relaxation mechanisms discussed. Relaxation p arameters were found to be derived from two-exponential fits of experi mental data. These parameters were not related to structural parameter s of cokes obtained in subsequent studies by high resolution NMR of H- 1 and C-13.