Deep Desulfurization of Fuels by Heteropolyanion-Based Ionic Liquid

Bull. Korean Chem. Soc. 2013, Vol. 34, No. 1 225
Deep Desulfurization of Fuels by Heteropolyanion-Based Ionic Liquid
Jinlei Li, Bing Hu, and Chuanqun Hu
hbwh04@163.com
School of Chemical and Environmental Engineering, Hubei University of Technology, Wuhan 430068, PR China
Abstract
A new heteropolyanion-based ionic ([Hmim]5PMo10V2O40) was synthesized by the reaction of molybdovanadophosphoric acid (H5PMo10O40) with N-methylimidazole. [Hmim]5PMo10V2O40 showed a high catalytic activity in the oxidative desulfurization of sulfur-containing compounds in 1-methylimidazolium tetrafluoroborate ([Hmim]BF4) ionic liquid using 30% aqueous H2O2 as the oxidant. The catalytic system was of high activity, simplified workup and flexible recyclability.
The catalytic oxidation reactivity of sulfur-containing compounds decreased in the order dibenzothiophene (DBT) > 4,6-dimethyldibenzothiophene (4,6-DMDBT) > benzothiophene (BT). The influences of various parameters including reaction time (t) and temperature (T), catalyst dosage, and oxidant to sulfur molar ratio n(O)/n(S) on the desulfurization of model oil were investigated in details. 99.1% of DBT conversion in the model oil was achieved at atmospheric pressure under the optimal conditions: n(O)/n(S) = 4:1, 60 oC, 100 min and molar ratio of catalyst to sulfur of 0.062. The ionic liquid can be recycled six times without significant decrease in activity.
Molybdovanadophosphate heteropoly acid showed high reactivity for esterification32,33 and oxidation reactions.35-38 However, to the better of our knowledge, limited work has been reported on the study of molybdovanadophosphatebased ionic liquid for oxidative desulfurization. Herein, a new heteropolyanion-based ionic liquid [Hmim]5PMo10V2O40 was synthesized by the reaction of H5PMo10V2O40 with the ionic liquid N-methylimidazolium, and used as the catalyst in the ODS process. Moreover, the influences of reaction conditions, such as reaction time and temperature, catalyst amount, molar ratio of H2O2 to DBT (n(O)/n(S)) on the desulfurization were investigated in details. 
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