Extraction of nitrogen compounds from diesel fuel using imidazolium- and pyridinium-based ionic liquids: Experiments, COSMO-RS prediction and NRTL correlation (original) (raw)
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Fuel Processing Technology, 2015
Seventeen ionic liquids (ILs), containing imidazole (7) and quaternary ammonium groups (10), were tested in the removal of nitrogen compounds present in the gas oil feed for diesel fuel production. A model mixture composed by quinoline, indole, and carbazole in hexadecane/toluene was used to run experiments with a Feed/IL ratio of 20/1 and 30°C. In general, the synthesized ILs presented higher removals of indole and carbazole than of quinoline. Additionally, when the carbon number of the carboxylate counterpart of the quaternary ammonium ILs increased, the carbazole removal increased. Further experiments using model mixtures that contained also benzothiophene and benzothiophene and aniline, showed that none of these added compounds affected the ILs solubility for indole and carbazole under the same experimental conditions. Experiments carried out in a batch setup using straight run gas oil (SRGO) proved that only triethylmethylammonium butyrate and triethylmethylammonium acetate of all the ILs selected, presented good nitrogen removal capabilities and adequate chemical stabilities at the experimental conditions used. Therefore, they were chosen for a dynamic study that showed that a 30% organic nitrogen extraction could be attained when 200 and 170 mL per gram of material had passed before a regeneration process was required.
Industrial & Engineering Chemistry Research, 2009
The extraction of trace polar compounds, among them neutral nitrogen-containing compounds (N-compounds), has received much attention from refiners because of their inhibiting effect on the hydrodesulfurization (HDS) process. Recently, we have shown that chloride-based ionic liquids (ILs) can selectively extract N-compounds from straight-run diesel feeds. However, the measurable solubility of ILs in hydrocarbon fuel is not a desired outcome of the process. Thus, the covalent binding of ILs moieties on polymers was studied. Starting from Merrifield resin, three resins were prepared with imidazolium, pyridinium, and triethylammonium chloride functionality. The resins were evaluated using a synthetic solution with dibenzothiophene and carbazole as model compounds, and a high selectivity for N-compounds was found. Imidazolium and pyridinium resins were then further evaluated using straight-run diesel feed containing 13400 ppm S and 105 ppm N. The selectivity toward N-compounds was comparable to the selectivity observed with ILs. Moreover, the resins could be easily regenerated using a protic solvent like methanol.
Industrial & Engineering Chemistry Research, 2008
Extraction of neutral nitrogen-containing compounds (N-compounds) has been investigated with chloride based ionic liquids (ILs) with varying cation classes (imidazolium, pyridinium). ILs were first discriminated by their mutual solubility of ILs and model fuel. Low solubility of 1-butyl-3-methylimidazolinium chloride (BMImCl) and 1-octylpyridinium chloride (OcPyCl) in the model fuel was observed. The ILs were then evaluated using a synthetic solution with dibenzothiophene and carbazole as model compounds, and a high selectivity for N-compounds was found. BMImCl and OcPyCl were then evaluated using straight-run diesel feed, containing 13 400 ppm S and 105 ppm N. An extraction of up to 50% of the N-compounds was obtained in one step whereas the sulfur concentration reduction was only 5%. Both ILs can be regenerated using small amount of water. Extracted compounds could be then extracted using toluene. The major constituents were identified by GC-MS. Analysis of the extracted compounds emphasized the selectivity of the extraction process. Furthermore, refractory sulfur-containing compounds (S-compounds) and polyaromatics were also identified in the extract. * Corresponding authors.
Liquid-liquid extraction is an alternative method that can be used for desulfurization and denitrification of gasoline and diesel fuels. Recent approaches employ different ionic liquids as selective solvents, due to their general immiscibility with gasoline and diesel, negligible vapor pressure, and high selectivity to sulfur-and nitrogen-containing compounds. For that reason, five imidazoliumbased ionic liquids and one pyridinium-based ionic liquid were selected for extraction of thiophene, dibenzothiophene, and pyridine from two model solutions. The influences of hydrodynamic conditions, mass ratio, and number of stages were investigated. Increasing the mass ratio of ionic liquid/model fuel and multistage extraction promotes the desulfurization and denitrification abilities of the examined ionic liquids. All selected ionic liquids can be reused and regenerated by means of vacuum evaporation.
Extraction of nitrogen compounds from model fuel using 1-ethyl-3-methylimidazolium methanesulfonate
Separation and Purification Technology, 2018
Removal of nitrogen compounds is an essential process in the fuel processing industry. In this work, the extraction performance of 1-ethyl-3-methylimidazolium methanesulfonate ([Emim][MeSO 3 ]) ionic liquid in removing pyrrole, indoline, pyridine and quinoline from cyclohexane is investigated. The ternary liquid-liquid equilibria for four systems containing [Emim][MeSO 3 ] + pyrrole/indoline/pyridine/quinoline + cyclohexane were predicted using COSMO-RS and validated experimentally at 298.15 K under atmospheric pressure, with feed concentrations of nitrogen compounds ranging from 5 to 50 wt. %. Othmer-Tobias and Hand correlations confirmed the consistency of the experimental data. The tie-lines obtained experimentally and predicted with COSMO-RS were in good agreement. Additionally, the non-random two-liquid (NRTL) model was successfully employed to correlate the experimental tie-lines. The effects of basicity of nitrogen compounds toward extraction efficiency were also investigated. The selectivity and distribution ratio results demonstrated the suitability of [Emim][MeSO 3 ] as an extraction solvent for removing nitrogen compounds from fuel. Finally, the multicomponent extraction confirmed the performance of [Emim][MeSO 3 ] for extractive denitrogenation. In all ternary systems investigated in this work, the concentration of cyclohexane in the extract phase was very small and the presence of the IL in the raffinate phase was negligible indicating minimum cross contamination between the extract and raffinate phases.
Journal of Chemical & Engineering Data, 2010
In this work, the ability of some ionic liquids ([C 8 mim][BF 4 ], [C 8 mim][NTf 2 ], and [C 2 mim][EtSO 4 ]), which have shown to be suitable as extraction solvents for the desulfurization of fuel oils, has been tested to carry out simultaneous denitrogenation. For this purpose, the liquid-liquid equilibria of these ionic liquids with pyridine and n-hexane have been determined at 298.15 K and atmospheric pressure. With the idea of giving useful parameters for the design of extraction units, the simultaneous correlation of five ternary systems involved in the gasoline and diesel desulfurization was carried out with the nonrandom two-liquid (NRTL) equation. The best results were achieved for a value of the nonrandomness parameter R) 0.3.
Journal of Environmental Protection, 2011
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 2 mim] [Cl]) was used as an extractant. Liquid-liquid extraction by using 1-ethyl-3-methylimidazolium chloride [C 2 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.
Extractive Denitrogenation of Fuel Oils with Ionic Liquids: A Systematic Study
Energy & Fuels, 2016
Ionic Liquids (ILs) have been suggested as useful extractants of aromatic nitrogencontaining compounds (N-compounds) from fuel oils. In this systematic study, ILs based on common cations and anions are employed as extractants of the archetypical N-compounds pyridine and indole from a model oil consisting of decane and toluene. The performance of these ILs as extractants of N-compounds is compared and rationalized. It is demonstrated that the cation and anion sizes (offering more surface area for extractants to interact) are the major
Industrial & Engineering Chemistry Research, 2015
The ionic liquids 1-butyl-1-methylpyrrolidinium trifluoromethanesulfonate, [BMpyr][TfO], 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide, [BMpyr][NTf 2 ], and 1-butyl-1-methylpyrrolidinium dicyanamide, [BMpyr]-[DCA], have been studied as solvents for the extraction of benzene from its mixtures with several aliphatic hydrocarbons. The liquid−liquid equilibrium (LLE) of the ternary systems {octane (1) + benzene (2) + [BMpyr][TfO] (3)}, {decane (1) + benzene (2) + [BMpyr][TfO] (3)}, {dodecane (1) + benzene (2) + [BMpyr][TfO] (3)}, {dodecane (1) + benzene (2) + [BMpyr][NTf 2 ] (3)}, and {dodecane (1) + benzene (2) + [BMpyr][DCA] (3)} at T = 298.15 K and atmospheric pressure was carried out. The solute distribution ratio and selectivity values derived from the tie-lines were used to evaluate if the studied ionic liquids can be used as extraction solvents, and the obtained values were compared with those found in the literature for the traditional organic solvents. Finally, experimental LLE data for the ternary mixtures were correlated by means of the non-random two-liquid (NRTL) thermodynamic model.
On the Extraction of Aromatic Compounds from Hydrocarbons by Imidazolium Ionic Liquids
International Journal of Molecular Sciences, 2007
The liquid-liquid equilibrium for the ternary system formed by n-octane and aromatic (alkylbenzenes) and heteroaromatic compounds (nitrogen and sulfur containing heterocyles) and 1-alkyl-3-methylimidazolium ionic liquids (ILs) associated with various anions has been investigated. The selectivity on the extraction of a specific aromatic compound is influenced by anion volume, hydrogen bond strength between the anion and the imidazolium cation and the length of the 1-methyl-3-alkylimidazolium alkyl side chain. The interaction of alkylbenzenes and sulfur heterocyles with the IL is preferentially through CH-π hydrogen bonds and the quantity of these aromatics in the IL phase decreases with the increase of the steric hindrance imposed by the substituents on the aromatic nucleus. In the case of nitrogen heterocycles the interaction occurs preferentially through N(heteroaromatic)-H(imidazolium) hydrogen bonds and the extraction process is largely controlled by the nitrogen heterocycle pKa. Competitive extraction experiments suggest that benzene, pyridine and dibenzothiophene do not compete for the same hydrogen bond sites of the IL.