HIGH FIELD-HIGH FREQUENCY ELECTRON-SPIN-RESONANCE STUDY OF THE ULTIMATE THERMOCATALYTIC HYDROCONVERSION OF HEAVY PETROLEUM CUTS

Various cokes produced during thermocatalytic hydroconversion of heavy petroleum cuts were studied by esr spectroscopy at 9 GHz. We observed that the evolution of the radical concentration of coke with the leve l of conversion (percentage of catalyst being constant) exhibited a ma ximum while the one of the yield of coke exhibited a minimum. This res ult could be interpreted by the presence of several coke species with different radical concentration and with relative concentration depend ing on the percentage of catalyst (at constant conversion level) and o n the conversion level (at constant percentage of catalyst). This inte rpretation has been confirmed by the detection at 245 GHz and 440 GHz of g-heterogeneity in coke spectra which could not be observed at 9 GH z.