Visible Light-Induced Desulfurization Process for Catalytic-Cracked Gasoline Using an Organic Two-Phase Extraction System

Abstract

A desulfurization process, based on photoinduced electron-transfer oxidation using 9,10-dicyanoanthracene (DCA) and organic two-phase extraction, has been applied to the desulfurization of catalytic-cracked gasoline (CCG). Sulfur-containing compounds (thiol, disulfide, and thiophenes), in acetonitrile solution, are photooxidized by photoirradiation, at wavelengths of λ > 400 nm in the presence of DCA, to form highly polarized compounds (sulfoxide, sulfone, and sulfate anion), and these compounds do not distribute into the CCG. Thus, when CCG and acetonitrile solution are mixed and are photoirradiated with DCA, the sulfur-containing compounds are extracted into the acetonitrile phase and are photooxidized, thus providing the successive removal of sulfur from CCG to acetonitrile under moderate conditions. In this way, the sulfur content of CCG is reduced successfully from 100 ppm to less than 30 ppm. The large quantity of olefins contained in the CCG is minimally photooxidized, owing to their small fluorescence quenching rate with DCA, and thus the desulfurized CCG has the same high octane number as that of the feed CCG.