Effects of phenol on the properties of pitch produced thermally from the petroleum vacuum residue

A petroleum vacuum residue was thermally treated at 430 °C, with continuous addition of phenol to either the vapour phase or the liquid phase of the reacting system. Addition of phenol to the vapour phase increased the yield of the cracked oil and the fixed carbon of the residual pitch. When phenol was charged to the liquid phase, the yield of the oil remained unchanged, but the amount of the benzeneinsoluble matter in the pitch decreased, probably owing to the inhibition by phenol of the polymerization-condensation reactions of aromatic compounds. In both additions the cracked oil had a higher boiling point than that produced without phenol. Substitution of phenol with methyl groups increased the extent of cracking and coking properties (Roga Index) of the pitch. The effective order of phenol and its derivatives is: Phenol < m-Cresol < o-Cresol < p-Cresol < 2, 4-Dimethylphenol < 2, 6-Dimethylphenol < 2, 4, 6-Trimethylphenol Polyhydric phenol, e.g. catechol, and naphthol also enhanced the cracking reactivity of the residue.