Separation of multiple sulfides from FCC gasoline by ionic liquid: Screening, phase behavior and molecular mechanism

A comprehensive MINLP-based CAILD method was developed for FCC gasoline extraction desulfurization (EDS). Distribution coefficients and selectivities of ILs were calculated by COSMO-RS model, then statistically integrated into a comprehensive index through fuzzy comprehensive evaluation method with entropy weighting method. Based on this index together with melting points and viscosities of ILs estimated by QSPR methods, a MINLP problem for CAILD was formulated and solved. [BMPy][DCA] was identified as the optimal extractant for simultaneously removing multiple thiophenes from isooctane. LLE data of isooctane + TS/BT/DBT/4,6-DMDBT + [BMPy][DCA] were measured and correlated by NRTL model to confirm the screening result. The consistency of the obtained model parameters was checked. Molecular thermodynamics calculations were performed synergistically to provide microscopic insights into the EDS mechanisms. A preliminary separation of sulfides was simulated to show [BMPy][DCA]'s excellent industrial performance. The method could be broadened to other applications including denitrification and dearomatization across various fuels.