Fast oxidative desulfurization of fuel oil using dialkylpyridinium tetrachloroferrates ionic liquids

In this work, a series of Lewis acidic ionic liquids (ILs), dialkylpyridinium tetrachloroferrates [(C4MPy)-M-3] FeCl4,[(C8MPy)-M-3] FeCl4, and [(C8MPy)-M-3] FeCl4), was synthesized and utilized as extractant and catalyst to investigate the oxidative removal of dibenzothiophene (DBT) from model oil, with 30 wt% hydrogen peroxide (H2O2) solution as oxidant. The effects of reaction time, temperature, H2O2/DBT molar ratio, initial sulfur content, IL/oil mass ratio, and alkyl chain length of IL cation ring on the DBT removal of model oil were investigated in detail. Dialkylpyridinium tetrachloroferrates ILs presented good catalytic activity and high extraction performance on the desulfurization of model oil, with the advantages of fast reaction equilibrium, high sulfur removal of 100%, low temperature, and low mass ratio of IL/oil. The desulfurization system could be recycled twice without a significant decrease in desulfurization activity. Kinetics of oxidative desulfurization of DBT by H2O2 and [(C4MPy)-M-3] FeCl4 is first-order with an apparent rate constant of 0.9951 min (-1) at 1/3IL/oil mass ratio and 298 K. [(C8MPy)-M-3] FeCl4 can reduce sulfur content in actual gasoline from 468 ppm to 261 ppm with a sulfur removal of 44% at IL/gasoline mass ratio of 1/3. The present work shows that fuel oil can be purified into ultralow sulfur fuels through further deep oxidative desulfurization using acidic ILs after hydrodesulfurization. (C) 2012 Elsevier Ltd. All rights reserved.