Acid Dicationic Ionic Liquids as Extractants for Extractive Desulfurization

Abstract

A series of imidazole- and pyridine-based dicationic ionic liquids (DILs) were synthesized and employed in extractive desulfurization (EDS) for the removal of sulfur compounds from commercial fluid catalytic cracking (FCC) gasoline. The influence parameters in the EDS process and regeneration of DILs are discussed. Under optimum operating conditions, the desulfurization efficiency can reach 79.72%. After five cycles, the sulfur content was reduced to less than 10 μg/g, and deep desulfurization was realized. The regeneration of the used DILs was performed by back-extraction, and the Fourier transform infrared and 1H nuclear magnetic resonance (NMR) spectra proved that the structure of DILs did not change. The relationship between acid strength and the desulfurization effect of DILs was studied by UV–vis spectroscopy. According to 1H NMR characterization, the main mechanism of the DILs' EDS process may be the interaction of π–π bonds. It is inferred from the chemical shift that the DILs have larger cation volume, which was conducive to increasing the aromatic π-electron density, producing stronger π–π interaction between the cations and aromatic sulfides, and thus having better EDS effect than ILs with mono-cationic. Finally, the adaptability of DILs was studied, and DILs have excellent desulfurization adaptability for different FCC gasolines.

Polyoxometalate Dicationic Ionic Liquids as Catalyst for Extractive Coupled Catalytic Oxidative Desulfurization

“…Many ILs have been developed which are used as both the catalyst and extractant. Usually, the cation side of ILs influences the extraction ability of this material for DBT removal [38]. Therefore, the extraction ability of DILs was investigated.…”

“…In addition, through electrostatic interaction and hydrogen bonding, the double cation can be well connected with the anion, so as to improve the overall catalytic activity of the catalyst. Due to their unique properties, DILs have been successfully used and achieved ideal effects in esterification, supercapacitor, biodiesel catalysis and extractive desulfurization as eutectic solvents/catalysts, electrolyte additives, catalysts and extractant, respectively [35][36][37][38]. In our group's recent research results, a series of novel binuclear magnetic ionic liquids (MILs) [Cn(MIM)2]Cl2/mFeCl3 (n = 2, 4 or 6 and m = 1, 2 or 3) were synthesized and used as catalysts for the desulfurization with oxidant H2O2 and extractant acetonitrile [39].…”

Synergistic Catalysis of Thermoregulated Ionic Liquid/p-Toluenesulfonic Acid for Alkylation Desulfurization of Fluid Catalytic Cracking Gasoline

“…The 1 H NMR data are shown in Figure . The chemical shift of ring protons in T (line a) were upfield than ring protons in TRIL (line b) because the average electron density of each ring carbon in PTSA was lower than that in T . It can be observed that the peak shape of the active hydrogen spectra changed significantly and the chemical shift of ring protons in TRIL moved into higher field after extraction (line c).…”

Extractive–oxidative desulfurization of model fuels using imidazole-based dicationic ionic liquids as extractants

“…The results showed that due to the addition of solvent, the viscosity of the composite extractant was greatly reduced, the mass transfer process was enhanced, and a high extraction performance was achieved. Li et al 35 synthesized a series of imidazole- and pyridine-based binuclear ionic liquid extractants for extractive desulfurization of fuel oil. Due to the large cation volume of the dicationic ionic liquid, its cation has a large aromatic π electron density, which can effectively reduce the electrostatic force between the cation and anion, increase the π–π interaction between the cation and sulfide, and make it easier to extract sulfide from the oil phase.…”