Abstract: A variety of hydrodesulfurization process schemes for treating FCC naphtha was discussed and compared. It is found that cutting FCC naphtha into a light naphtha fraction (LNF) and a heavy naphtha fraction (HNF) treating respectively can significantly reduce the rate of olefin saturation during hydrodesulfurization process. The mercaptans in LNF can be removed by alkaline extraction and the olefin content of LNF is not affected significantly. Adding a reactor to selectively remove diene in HNF is necessary, due to the formation of gum is promoted by diene under relatively mild conditions. The existence of hydrogen sulfide in recycle hydrogen may suppress hydrodesulfurization reactions and promote olefin saturation, thus a system for removing hydrogen sulfide in recycle hydrogen is required. The mercaptans in product can be removed by fixed-bed oxidation. Finally, based on the above findings, considering the feedstock properties, reaction kinetics and commercial requirements, a selective hydrodesulfurization process scheme is determined.

Key words: FCC gasoline, selective hydodesulfurization, process, mercaptan