Desulfurization of Heavy Oil by Using Combination of Oxidation and Mild Thermolysis

Abstract

Heavy fuel oils usually have high sulfur content and most of the sulfur compounds have bulky thiophenic structures which resist desulfurization. Oxidation of these sulfur compounds to sulfones weakens the C–S bonds and sulfur can be removed as SO₂ by thermolysis. This study investigated oxidative desulfurization of heavy vacuum gas oil (2.81 wt% S). Oxidation was achieved with hydrogen peroxide and formic acid. Then, the oxidized feed underwent thermolysis at 355-410 °C for 0.5-3 h to identify the maximum desulfurization with minimum feed conversion to light products. The effects of parameters such as time and temperature were studied. Temperature had significant effects in comparison to other parameters. Desulfurization of 65 % with 6 wt% conversion of feedstock to light products was achieved under the optimum conditions.