Extraction of polycyclic aromatic hydrocarbons from fluid catalytic cracking diesel with ionic liquids

Ionic liquids (ILs) as promising green solvents were first proposed to extract polycyclic aromatic hydrocarbons (PAHs) from fluid catalytic cracking (FCC) diesel. The COSMO‐RS model was used for preliminary screening of IL extractants. The liquid–liquid equilibrium (LLE) experiments were performed to show that the IL [BMIM][BF4] has a high selectivity for the model oil system. Further, the LLE experimental results show that the solubility of 1‐methylnaphthalene in [BMIM][BF4] is relatively low, while the IL exhibits a high selectivity of n‐hexadecane to 1‐methylnaphthalene. This means that the use of [BMIM][BF4] can obtain the high‐purity products when considering the almost nonvolatility of IL. Compared to the benchmark process, the multistage countercurrent–reflux extraction process can improve the PAHs purity by about 2% at the expense of 5.06% total annual cost and 6.42% energy consumption, rendering the use of IL to extract PAHs from FCC diesel more feasible in industry.