Extractive denitrogenation of shale oil using imidazolium ionic liquids

摘要

The potential applications of shale oil as a substitute energy source are adversely influenced due to its high nitrogen content.In this work,four imidazolium ionic liquids(ILs),i.e.,1-butyl-3-methylimidazolium chloride([Bmim]Cl),1-butyl-3-methylimidazolium acetate([Bmim]Ac),1-butyl-3-methylimidazolium acetate/ZnAc2([Bmim]Ac/ZnAc2)and 1-butyl-3-methylimidazolium chloride/ZnAc2([Bmim]Cl/ZnAc2),were used to extract the basic nitrides and neutral nitrides from shale oil.The influence of extraction time,temperature,properties of N-compounds,ILs structure,mass ratio of IL/oil,multiple cycles of denitrogenation,physical mixing of ILs and ILs recyclability on extractive denitrogenation was systematically investigated.The denitrogenation performance of all ILs was determined and investigated from micro-level view withσ-profile.It was observed that,ILs composed of anions with weaker HB acceptor capacity,have the higher N-extraction efficiency to the neutral nitrogen compounds with weaker HB acceptor capacity.More than 96%N-extraction efficiency was achieved at the end of a single extraction cycle for time<10 min under 40℃C and 1:1 of IL:oil(w/w),especially 100%N-extraction efficiency was realized for carbazole and indole.The N-extraction efficiency up to 60.1%and 53.7%for real shale oil was realized by[Bmim]Ac and[Bmim]Ac/ZnAc2,respectively,which are about 10%better than other non-hydrodenitrogenation technologies.Moreover,[Bmim]Ac and[Bmim]Ac/ZnAc2 exhibited almost the same extractive denitrogenation performance after regeneration.This work has developed a new approach to lessen the nitrogen content of shale oil effectively and economically.