Selective denitrogenation using Zn-containing ionic liquids as extractants

In recent years, desulfurization and denitrogenation of transportation fuels have attracted increasing interest due to the stringent regulation on the environmental pollution caused by exhaust gases such as SOx and NOx to the atmosphere. Industrially, the removal of organosulfur and organonitrogen compounds in fuel oils is being carried out by means of a simultaneous catalytic hydrodesulfurization (HDS) and hydrodenitrogenation (HDN) process. However, current hydrotreating catalysts used for this purpose are not very effective for the removal of aromatic sulfur compounds and aromatic nitrogen compounds. Furthermore, the catalysts for the HDS are easily poisoned by the presence of nitrogen compounds, which preferably adsorb on the surfaces of the catalyst. During the course of our study, we found that effective denitrogenation of model oil containing aromatic nitrogen compounds (quinoline, indole, or acridine) was achieved by using Imidazolium-based zinc-containing ionic liquids (ILs), [1-R-3-R′-imidazolium]alkylsulfate-ZnCl2 (R, R′ = H or alkyl) as an extractant at an ambient condition.