Desulfurization of FCC gas oil by solvent extraction, photooxidation, and oxidizing agents

A deep desulfurization process for FCC gas oil by a combination of liquid-liquid extraction, photochemical reaction, and treating with oxidation agents has been investigated. The process often represented by the model heterocyclic compounds, benzothiophenes (BTs) and dibenzothiophenes (DBTs). The process is comprised of three stages. Extraction of the sulfur-containing compounds from a catalytic cracked gas oil by acetonitrile, photooxidation, and photodecomposition of the sulphur compounds in the acetonitrile phase by ultraviolet irradiation from a high pressure mercury lamp, and recovery of the sulphur from the irradiated oil and treatment with oxidizing agent. The process was carried under conditions of room temperature and atmospheric pressure. Acetonitrile/water azeotropic mixture has been recycled successfully through distillation column. The sulfur in this gas oil has been decreased from 1800 ppm to 550 ppm after photo-desulfurization, and 508 ppm after treatment with the oxidizing agents. The total yield of the oil was 90-95%.