The Study On Coupled Oxidative-Extractive Deep Desulfurization Of Ionic Liquid

Presently,the presence of sulfur compounds into diesel fuel is one of major environmental concerns,thus,its reduction is given a significant consideration.The traditional hydrodesulfurization technology requires harsh reaction conditions and it is difficult to remove thiophene sulfides completely.The desulfurization technology based on ionic liquids delivers good desulfurization performance under the mild operating conditions with low energy consumption and good regeneration performance,so it has great development prospects.In this study,ionic liquid-based oxidative desulfurization(ODS)coupled with organic solvent-based extractive desulfurization(EDS)of model oil and real diesel was performed and the desulfurization performance was investigated.Two kinds of Br(?)nsted acidic ionic liquids(ILs)[HNMP]HSO4 and[HNMP]H2PO4 were prepared.Ionic liquid as catalyst and extractant for ODS,H2O2 as oxidant and N-methylpyrrolidone(NMP)as extractant for EDS,were used to investigate the desulfurization performance for model diesel(initial sulfur content 500 ppm),FCC diesel(initial sulfur content 500 ppm)and straight-run diesel(initial sulfur content 493.7 ppm).Ionic liquid exhibiting the better performance was selected to examine the effect of reaction conditions on the S-removal efficiency.The results show that(1)for the[HNMP]H2PO4-H2O2-NMP ODS coupled with EDS,at the reaction temperature of 80?,the ILs/Oil mass ratio of 1:1,the O/S molar ratio of 64,for reaction time of 4h/5h(4h for model oil 4h,5h for FCC diesel and straight-run diesel),NMP/Oil mass ratio of 1:2,for extraction time of 30 min,through one step ODS and two steps EDS,the S-removal efficiency for model oil was 91%and the S-removal efficiency for diesel was 95%.After the regeneration,ionic liquids have potential to be recycled.(2)Under the optimal reaction conditions,the[HNMP]H2PO4-H2O2-NMP system can completely remove the methyl sulfide and ethanethiol in the model oil through one step ODS.The thiophene can be subjected to one step ODS and three steps EDS to achieve the goal of deep desulfurization,(3)Compared with the caustic washing desulfurization,organic solvent-based EDS,ionic liquid-based EDS,and organic solvent-based ODS copled EDS,the coupled ODS(using ILs)and EDS(using organic solvent)is preferable technology.This technology can achieve the deep desulfurization of straight-run diesel,which is harder through the other methods.