| Abstract
| - Brazilian vacuum residue (VR) was separated into insoluble and soluble fractions usingn-heptane−toluene mixtures (Heptol). Coking tests performed on the soluble fractions showedthat asphaltenes vary in regard to the extent to which they form coke. VR asphaltenes weresubfractioned into AS 0−10%, AS 10−20%, AS 20−30%, and AS 30−40% by stepwise extractionusing Heptol. The AS 20−30% and AS 30−40% fractions had greater aromaticity and a higherproportion of quaternary aromatic carbons, as well as a larger unit size. These type II asphaltenesproduced more coke than did type I asphaltenes, which consist of the AS 0−10% and AS 10−20% fractions.
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