Ionic Liquid Assisted Extraction of Nitrogen and Sulphur-Containing Air Pollutants from Model Oil and Regeneration of the Spent Ionic Liquid

Abstract

Removal of air pollutants, such as nitrogen and sulphur containing compounds from a model oil (dodecane) was studied. An ionic liquid (1-ethyl-3-methylimidazolium chloride [C<sub>2</sub>mim] [Cl]) was used as an extractant. Liquid-liquid extraction by using 1-ethyl-3-methylimidazolium chloride [C<sub>2</sub>mim] [Cl] was found to be a very promising method for the removal of N- and S-compounds. This was evaluated by using a model oil (dodecane) with indole as a neutral nitrogen compound and pyridine as a basic nitrogen compound. Dibenzothiophene (DBT) was used as a sulphur compound. An extraction capacity of up to 90 wt% was achieved for the model oil containing pyridine, while only 76 wt% of indole in the oil was extracted. The extraction capacity of a model sulphur compound DBT was found to be up to 99 wt%. Regeneration of the spent ionic liquid was carried out with toluene back-extraction. A 1:1 toluene-to-IL wt ratio was performed at room temperature. It was observed that, for the spent ionic liquid containing DBT as a model compound more than 85 wt% (corresponding 3852 mg/kg) could be removed from the oil. After the second regeneration cycle, 86 wt% of the DBT was recovered from the ionic liquid to toluene. In the case of indole as the nitrogen containing species, more than 99 wt%, (corresponding to 2993 mg/kg) of the original indole was transferred from the model oil to the ionic liquid. After the first-regeneration cycle of the spent ionic liquid, 54 wt% of the indole–in-IL was transferred to toluene. Thus, both extractions of nitrogen and sulphur model compounds were successfully carried out from model oil and the back-extraction of these compounds from the ionic liquids to toluene demonstrated the proved the concept of the regeneration point of view

Selected issues related to the toxicity of ionic liquids and deep eutectic solvents—a review

“…This property may be controlled by, for example, changing the anion from [Cl] − to [PF 6 ] − . One of the other factors is the length of the alkyl chain of the cation (Anugwom et al 2011). …”

“…New solutions have been found in the field of utilising traditional solvents (such as water as a solvent or water and carbon dioxide) at supercritical state, but the biggest group of them still consists of organic solvents. Table 1 summarises characteristics of green solvents-the biggest group of which constitute esters, (Paryjczak 2008) together with selected milestones in their research (Zabielska-Matejuk 2009;Anugwom et al 2011;Dominguez de Maria 2012).…”

Aromatic sulfur‐nitrogen extraction using ionic liquids: Experiments and predictions using an a priori model

“…Further, ILs does not affect the chemical structure of the diesel compounds as well as cetane number of the diesel oil. 2,19 However, in a recent work, 20 it was found that the regeneration of ILs is difficult for a LLE operation involving nitrogen species. In their work, toluene was used as a regenerative solvent to remove indole and dibenzothiophene (DBT) from 1-ethyl-3-methylimidazolium chloride.…”

Focus on Fuel Quality: Removal of Sulfur-, Nitrogen-, and Oxygen-Containing Aromatic Compounds by Extraction from Hydrocarbons into the Regenerable Ionic Liquid

“…It should be noted that the results on Py extraction presented in Table 2 are comparable to the literature data. 15 The effect of d metals on the extent of extraction of Py, DMDBT, and anthracene-9-carboxaldehyde (ACA) allows us to suppose that the heteroatom plays the crucial role in the formation of complexes with metal ions but not the aromatic ring, as assumed earlier. 20 For ACA, the introduction of additives does not produce any substantial effect on the efficiency of extraction, which may be explained by the poor ability of the aldehyde to complex formation with the chosen metal ions.…”

“…15 The extraction was carried out at 60°C for 15 min. When the model oil containing Py as a nitrogen-containing compound was extracted (1:5 IL/oil weight ratio) at 60°C, 70% of the nitrogen-containing compound was removed at the equilibrium conditions.…”