Fine-tune simultaneous dearomatization, desulfurization and denitrogenation of liquid fuels with CO2-derived cyclic carbonates

Abstract

In this work, eight CO2-derived cyclic carbonates, namely ethylene carbonate (Eth-C), propylene carbonate (Pro-C), butylene carbonate (But-C), hexylene carbonate (Hex-C), cyclohexene carbonate (Cyc-C), styrene carbonate (Sty-C), glycerol carbonate (Gly-C) and (Chloromethyl)ethylene carbonate (Chl-C) were evaluated as solvents to mitigate residual aromatic content in liquid fuels by envisioning an efficient liquid–liquid extraction process, using benzene, thiophene and pyrrole as benchmark compounds for dearomatization, desulfurization and denitrogenation processes. After evaluating at molecular scale by COSMO-RS method (activity coefficients and excess enthalpies of aromatic-cyclic carbonate mixtures), predictions of phase equilibria of ternary systems involving n-heptane are carried out by COSMO-based/Aspen methodology for evaluating the extractive properties of studied cyclic carbonates. Then, computational findings are experimentally validated for the representative Pro-C case through multicomponent liquid–liquid equilibria. Finally, the complete separation process was simulated by COSMO-based/Aspen methodology to evaluate solvent losses in extraction and distillation units, energy consumption, and aromatic purity for process specifications aimed at enhancing gasoline purity and recovery. Main results suggest that Pro-C provides promising process performance at a very competitive solvent to feed (S/F) ratio and specific energy consumption, positioning cyclic carbonates for studied separation.