Separation of Coker Gas Oil by Solvent Extraction

Separation of coker gas oil (CGO) by solvent extraction was studied for the recovery of aromatic hydrocarbons and upgrade of the oil to diesel fuel oil. CGO was analyzed by gas chromatograph to identify 17 kinds of aromatics, 16 kinds of alkanes and 6 kinds of alkenes, respectively. The liquid-liquid equilibrium extraction was conducted with furfural, sulfolane and methanol solvents. In all cases, the aromatic components in CGO were selectively extracted with the employed solvents. In the case of furfural without water, the distribution ratios of aromatics were larger than other solvents. With the solvent of sulfolane, the separation selectivities of aromatic components relative to nonaromatic components were larger than those with other solvents, although the distribution ratios of aromatics with sulfolane were approximately the same as those with other solvents. Methanol solvent without water could dissolve both aromatics and nonaromatics, thereby exhibiting low separation selectivity. However, the addition of water could improve the separation selectivities of aromatic components as much as those with furfural without water, and the distribution coefficient of methanol was the largest among the solvents used. When the aqueous solutions of sulfolane and methanol were used, di-cyclic aromatic components were selectively extracted among aromatic components. These kinds of solvents can be expected not only for the recovery of aromatic components, but also for the separation of aromatic components.