Removal of nitrogen compounds from diesel oil with eutectic ionic liquid

An eutectic ionic liquid (EIL), choline chloride/oxalic acid, was synthesized and its structure was characterized with FT-IR spectroscopy and ¹H-NMR. The denitrogenation performance of the EIL was investigated in detail using model oil and coker diesel oil as feedstock. Experimental results show that the removal efficiencies of quinoline and indole are almost 100% and 88.05%, respectively at 30℃ with the EIL to oil ratio of 1:7 (mass ratio), extraction time of 30 min and settling time of 2 h. It is also found that the choline chloride/oxalic acid presents a better denitrogenation performance for coker diesel oil, and the basic and total N-extraction efficiency can reach 96.61% and 71.5%, respectively. In addition, the basic N-removal efficiency can still reach 87.2% after four recycles of the EIL.