Research of desulfurization of dibenzothiophene with SO3H-functionalized morpholine heteropolyacid ionic liquid catalyst

In this work, several SO3H-functionalized strong Bronsted acidic morpholine phosphotungstic acid ionic liquid catalyst was synthesized and applied for oxidative removal of dibenzothiophene (DBT) from fuel. Chemical structure of the aforementioned catalyst was successfully characterized by FT-IR, H-1 NMR, XRD, and TGA. Meanwhile, the catalytic activity of the synthesized catalyst was also evaluated by investigating the removal of DBT from model fuel. The investigated results reveal that the optimal removal rate of DBT was 99.4 wt%, which was obtained under the optimum experimental conditions ([C(3)SO(3)Hnhm](3)PW12O40 was chosen as catalyst, the mass ratio of catalyst to model oil was 2 wt%, molar ratio of O/S was 15, reaction time of 105 min and reaction temperature of 50 degrees C). Moreover, this catalyst could be recycled at least six time without any decrease in catalytic activity. It was also found that the DBT was adsorbed to the cation through an electrostatic adsorption interaction between the morpholine ring (N+ position) and the S atom of DBT and the structure of DBT can be distorted by the acidity of the SO3H group, which makes it more susceptible to oxidization. Combined with the kinetic study, results suggested that oxidation of DBT was attributed to a pseudo-first-order kinetic reaction. (C) 2020 Elsevier B.V. All rights reserved.