Polymerization of deasphalted vacuum residue mixed with gum rosin for mesophase pitch production

Abstract

Waste from vacuum distillation of crude oil refineries in Indonesia is still not fully utilized. Vacuum residue is potential to be used as a feedstock to produce mesophase pitch by removing its asphaltene content (deasphalting) followed by thermal polymerization of the remaining aromatic compounds performed at low heating rate. Mesophase pitch is regarded as an excellent precursor for making a wide variety of industrial and advanced engineering carbon products such as carbon fibers, needle coke, Li-ion battery anodes. The objective of the present research is to investigate the effect of gum rosin addition to the deasphalted vacuum residue on the extent of the polymerization of aromatic compounds. Gum rosin is a residue of pine trees containing conjugated double bond compounds. It was used to maintain mesophase condition during polymerization to maintain polyaromatic formation. High polyaromatic composition forms anisotropic crystallite and favors high mechanical strength as the mesophase pitch is converted to engineering carbon. The polymerization occurred in a stirred tank reactor at heating rate of 5°C/min, maximum temperature of 350°C, and N2 flowrate of 100 mL/min. The amount of gum rosin mixed with the deasphalted vacuum residue was varied at 0% wt, 5% wt, 10% wt, and 15% wt of deasphalted vacuum residue. The result of analysis on mesophase pitches shows that increasing gum rosin composition from 0 to 10% reduced aromatic composition in mesophase pitch from 23 to 10%, but increased to 67% as the gum rosin content was increased to 15% wt. The largest crystallite size in the mesophase pitch, i.e. 44.5 Angstrom was achieved as the polymerization used 15% wt of gum rosin. All mesophase pitches have interlayer distance in average 4.12 Angstrom, slightly higher than 3.35 Angstrom (interlayer distance of fully ordered crystalline graphite).