Ionic liquids screening for desulfurization of natural gasoline by liquid–liquid extraction

Abstract

Seventy five ionic liquids (ILs) were tested as a sequestering agent of sulfured compounds in natural gasoline (NG). Desulphurization of NG was performed by means of liquid-liquid extraction method at room temperature and atmospheric pressure. Experimental ILs containing imidazolium, pyridinium, and ammonium cations along with organic and inorganic anions were synthesized conventionally and under microwave and sonochemical conditions. The effect of the molecular structure of ILs on the desulfurization efficiency of NG with high sulfur content was evaluated. Analysis indicated that the anion type played a more important role than the cation on the desulphurization process. ILs based on halogen-ferrates and halogen-aluminates exhibited the highest efficiency in sulfur removal, and their efficiency is further improved when there is an excess of metallic salt in a ratio of at least 1:1.3 during the synthesis of the corresponding IL. An explanation for the ability of metallic ILs to remove sulfur-containing compounds from natural gasoline based on the ratio of the ionic charge to the atomic radius is proposed. Furthermore, a method to recover and reuse water-sensitive to halogenated precursors is described.

Green Carboxylic Acid-Based Deep Eutectic Solvents as Solvents for Extractive Desulfurization

“…In contrast to these defects, ionic liquids (ILs) which possess many desirable properties, such as non-volatile, non-flammable, high thermal stability and good solubility [24][25][26] , have been widely 4 discussed as extractant in the desulfurization of fuel. In many studies [27][28][29] , imidazolium-based ILs, pyridinium-based ILs, ammonium salt-based ILs have been employed in EDS. Although ILs are widely applied to the extractive desulfurization, the process has still not been applied to the industry due to these factors like the high cost of ILs and high mutual solubility of the ILs with the liquid fuel 30 .…”

Recycling and recovery of ammonium-based ionic liquids after extraction of metal cations from aqueous solutions

“…The recovery of ILs containing sulfur compounds in their structure has also been achieved. In this case, the pH change was used to promote the precipitation of pollutants, which are filtered in order to get the base IL; it is worth highlighting that for this treatment, it is necessary to regenerate the anionic part [37].…”

Efficient Oxidative Desulfurization of Model Oil at Room Temperature with Ionic Liquid as Extraction Solvent

“…Among the alternative methods of desulfurization, extractive desulfurization is viewed to be among the most efficient but its industrial scale application entails the use of large volumes of volatile organic compound (VOC) extractants (Zhao et al, Optimization, 2010). To alleviate this problem, the extraction of sulfur compounds from fuels through ionic liquids (ILs) has been studied extensively (Likhanova et al, 2010). ILs are non-volatile, easy to handle, thermally robust, and non-explosive "designer solvents".…”

“…Being designer solvents, their physical and chemical properties can be altered to suit an application of interest through modifications on their cation and anion component (Bosmann et al, 2001;Cheng et al, 2008). Lewis and Brønsted -acidic ionic liquids employing mixtures of nbutyl-3-methylimiazolium chloride and nethyl-3-methylimidazolium chloride with AlCl3 have been proven effective for the extraction of sulfur containing compounds (Likhanova et al, 2010;Francisco et al, 2010) but these mixtures are unstable in air and sensitive to water making these of limited practical utility (Francisco et al, 2010).…”

“…In more recent studies, a fluoride-free Bronsted acid IL [Hnmp] H2PO4 (Zhao et al, Oxidation, 2009) and several pyridinium based ionic liquids (Zhao et al, Oxidation, 2010) were utilized both as catalyst and extractant in a combined oxidative and extractive desulfurization of fuels. The use of [RMIM][Halide] ionic liquids in oxidative desulfurization holds the advantage of convenience in preparation because, unlike in the preparation of the previously mentioned IL's, this only involves a one-step, one-pot, thermal or ultrasoundassisted synthesis (Seeberger and Jess, 2009;Likhanova et al, 2010).…”