STRUCTURAL-CHANGES DURING VISBREAKING OF LIGHT ARABIAN MIX SHORT RESIDUE - COMPARISON OF FEED AND PRODUCT ASPHALTENES

Structural parameters and physicochemical properties of asphaltenes se parated from light Arabian mix short residue and its visbroken product s (> 500-degrees-C) obtained from soaker visbreaking were determined b y i.r., n.m.r., v.p.o. and other classical techniques. The variations of these parameters with severity of operation measured in terms of co nversion (yield of material boiling < 150-degrees-C) were used to pred ict the cracking reactions occurring in residue during visbreaking. Th e data reveal that dealkylation of aromatics, resins and asphaltene cl usters are pronounced at quite low severities. and dehydrogenation and /or ring opening of the naphthenic part of these clusters also starts from the beginning of the reactions. These reactions are responsible f or increases in asphaltenes and coke yield with increasing conversion.