Research on a Dual Solvent To Separate Olefin/Aromatic–Sulfide from Heavy Fluid Catalytic Cracking Naphtha

Abstract

The separation of olefin from heavy fluid catalytic cracking (FCC) naphtha is beneficial to avoid the loss of octane number during the desulfurization process. Extractive distillation is a promising alternative to separate olefin and enrich sulfide at the same time. The vapor–liquid equilibrium of heavy FCC naphtha with different single solvents was studied first. Sulfolane showed the best ability to separate olefin with a selectivity coefficient θ of 2.81; however, sulfide selectivity coefficient β was only 1.78. N-Methylpyrrolidone showed the best ability to concentrate sulfide, with β up to 2.07 but lower θ of 2.74. The optimized dual solvent with a volume ratio of sulfolane/N-methylpyrrolidone at 85:15 (vol %) resulted in a selectivity coefficient θ of up to 4.01, while β was 1.97.