Estimation of Aromatic Ring Distribution for Heavy Oils and Bitumens by NMR

Based on the assumption of equal degree of substitution or equal number ofsubstituents on aromatic ring,the aromatic ring distribution of heavy oils and bitumens is es-timated by NMR proton spectra on the aromatics with the different ring number.Band as-signments of aromatic protons are checked with model mixtures. In this way the aromaticring distributions of four Alberta asphaltenes are estimated. The results show that the effectof the assumption above-mentioned on the error of the ring distribution estimate is insignifi-cant,and the content of aromatic condensed rings of Alberta asphaltenes is not high,whichis different from the traditional estimates.