High efficiency separation of olefin from FCC naphtha: Influence of combined solvents and related extraction conditions

Separation of olefin from fluid catalytic cracking (FCC) naphtha is a high way to protect the research octane number (RON) from a loss during hydrodesulfurization . Solvent extraction is a promising way to separate olefin and extract sulfides simultaneously. In order to realize effective separation of olefin from FCC naphtha, this paper focused on the development of a kind of high efficient solvent and optimization of corresponding operation conditions for olefin separation. The results showed the combined solvents consisted of sulfolane (95 v%) and N -methyl-2-pyrrolidone (5 v%) exhibited high separation capability for olefin, and the best solvent to oil ratio was 3:1. Based on the combined solvent and optimal solvent to oil ratio, the best olefin enrichment coefficient could be up to 97.63 indicating lots of olefin enriched in raffinate . The desulfurization efficiency exceeded 90% after 3-stage extraction by the combined solvents, which was close to and even prior to some kinds of ionic liquids . Moreover, the combined solvents exhibited remarkable stability, and variation of desulfurization efficiency of the combined solvents was only around 1% after recycled 8 times. These studies gave a high efficient way to upgrade clean gasoline by separating olefin and enriching sulfides from FCC naphtha.