Pyridinium-based temperature-responsive magnetic ionic liquid for oxidative desulfurization of fuels

A temperature-responsive magnetic ionic liquid (IL) N-butylpyridinium tetrachloroferrate ([BPy][FeCl4]) catalyst was prepared. Melting and solidification of [BPy][FeCl4] are reversible. In oxidative desulfurization process, the thermoregulated formation of liquid-liquid extractive and catalytic oxidation desulfurization system (ECODS) containing model oil, hydrogen peroxide and [BPy][FeCl4] was observed at 40 degrees C and higher sulfur removal was detected. After finishing reaction and cooling temperature, reaction system returns to liquid-solid state. Moreover, [BPy][FeCl4] exhibits a strong response to a magnet and can be easily separated from model oil by applying an external magnetic field, achieving five times recycling without significant decrease in activity. The effect of oxidative desulfurization of model oil with dibenzothiophene (DBT), benzothiophene (BT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT) was investigated, which reveals fast oxidative desulfurization ability. The sulfur removal of DBT, BT and 4,6-DMDBT could reach 95.3%, 75.0% and 54.8% in [BPy]FeCl4 for only 10 min. The amount of [BPy][FeCl4], H2O2/DBT molar ratio, temperature and the composition of [BPy][FeCl4] all played vital roles in desulfurization efficiency, which were also studied in detail to optimize the reaction conditions. (c) 2013 Elsevier B.V. All rights reserved.