Visbreaking reaction of atmospheric residue. Part 4. Structural analysis and reaction mechanism for taching atmospheric residue.

Abstract

in the presence of a diluent, namely, nitrogen, hydrogen, or tetralin as a hydrogen donor. A significant decrease in the molecular weight of the product residue was observed. The feed and the product residues were separated into six fractions. The distribution of the fractions was dependent on the diluent used, whereas the distillate yield was but slightly affected. Taching crude is essentially paraflins, saturates, and monoaromatics with long alkyl side chains comprising about 70% of the residue. Although the residue contained no asphaltenes (n-pentane insolubles), a considerable amount of asphaltenes was formed by visbreaking. The yield and structural change in the fractions were accounted for by the mechanism consisting of unimolecular decomposition and radical chain reaction.