Solvents For Extractive Desulfurization Research Articles

Desulfurization of Diesel Using Ionic Liquids: Process Design and Optimization Using COSMO-Based Models and Aspen Plus.

Sulfur dioxide emissions from fossil fuel combustion have been known to cause detrimental health and environmental effects. The currently used hydrodesulfurization (HDS) method employed by refineries has several drawbacks, such as excessive hydrogen consumption, high energy demand, and inability to remove complex organosulfur compounds, which have limited its ability to produce ultralow sulfur diesel (ULSD) at reasonable operating and capital costs. Ionic liquids (ILs) have been widely studied for their potential to replace conventional HDS. However, while their success has been demonstrated at the laboratory level, studies on industrial-scale feasibility and their integration into process simulators such as Aspen Plus are limited. In this work, 26 commercially available ILs have been screened using COSMO-based models and Aspen Plus for the desulfurization of diesel fuel and several possible process configurations have been examined. In particular, the challenge of ionic liquid regeneration, which has largely been ignored in the literature, has also been addressed and several potential regeneration methods have been proposed including extractive regeneration (E-RE) and stripping regeneration using nitrogen and air as stripping media (S-RE). The results indicate that, among the 26 ILs studied, 1-butyl-3-methylimidazolium thiocyanate is the most promising as a solvent for extractive desulfurization (EDS), E-RE, and S-RE. E-RE was found to be more effective for the removal of dibenzothiophene (DBT), while S-RE is more suited to the removal of thiophene and benzothiophene (BT). As a result, an optimized diesel desulfurization process using 1-butyl-3-methylimidazolium thiocyanate has been proposed that achieves ULSD with <10 ppm total sulfur in simulation studies, with complete recycling of the IL and minimal loss of the model diesel.

Separation of organosulfur compounds from heptane by liquid–liquid extraction with tricyanomethanide based ionic liquids. Experimental data and NRTL correlation

This work is an attempt to determine appropriate solvents for extractive desulfurization, which is the dominant alternative to the risky and expensive solution, which is hydrodesulfurization (HDS). The main part of this research is the study on (liquid + liquid) phase equilibria in {IL (1) + heptane, or thiophene, or 2-methylthiophene, or benzothiophene (2) binary systems and {IL (1) + thiophene/2-methylthiophene/benzothiophene (2) + heptane (3)} ternary system. In this work, five new synthesized tricyanomethanide – based ILs that is: N-(3-cyanopropyl)-N-methylmorpholinium tricyanomethanide, [Mo1,3CN][TCM], N-(3-hydroxypropyl)-N-methylmorpholinium tricyanomethanide, [Mo1,3OH][TCM], N-(3-cyanopropyl)pyridinium tricyanomethanide, [Py3CN][TCM], N-(3-hydroxypropyl)pyridinium tricyanomethanide, [Py3OH][TCM], N-(2-hydroxyethyl)pyridinium tricyanomethanide, [Py2OH][TCM] are analyzed as an extractant in desulfurization of model fuel. Based on the experimental ternary LLE data, the selectivity and solute distribution ratio are calculated and used to determine the efficiency of the tested ILs as solvents for the extraction of sulfur compounds from model fuel. The experimental results have been compared to literature data for other tricyanomethanide-based ILs and were discussed in terms of the selectivity and solute distribution ratio of separation of related systems. The NRTL equation was successfully used to correlate the LLE in binary systems as well as the experimental tie-lines.

Trihexyl(tetradecyl)phosphonium hexafluorophosphate as an promising Extractant for extractive desulfurization from liquid fuels

ABSTRACTExperimental data on extractive desulfurization (EDS) of dibenzothiophene (DBT), thiophene, benzothiophene, and other substituted derivatives of sulfur from liquid fuel using trihexyl(tetradecyl)phosphonium hexafluorophosphate ([THTDP][PF6]) have been presented. The Fourier transform infrared spectrophotometer, 1H-NMR, 13C-NMR, and 31P-NMR analysis have been discussed for molecular confirmation, and conductivity, solubility, and viscosity analyses of ([THTDP][PF6]) were investigated. The effects of time, temperature, S-compounds, ultrasonication, and recycling of ([THTDP][PF6]) on DBT removal from fuel were examined. Also, desulfurization of real fuels and multistage extraction was also tested. The data and results provided the significant insights of phosphonium ionic liquids as a promising solvent for EDS.

Computer‐aided design of ionic liquids as solvents for extractive desulfurization

Although ionic liquids (ILs) have been widely explored as solvents for extractive desulfurization (EDS) of fuel oils, systematic studying of the optimal design of ILs for this process is still scarce. The UNIFAC‐IL model is extended first to describe the EDS system based on exhaustive experimental data. Then, based on the obtained UNIFAC‐IL model and group contribution models for predicting the melting point and viscosity of ILs, a mixed‐integer nonlinear programming (MINLP) problem is formulated for the purpose of computer‐aided ionic liquid design (CAILD). The MINLP problem is solved to optimize the liquid‐liquid extraction performance of ILs in a given multicomponent model EDS system, under consideration of constraints regarding the IL structure, thermodynamic and physical properties. The top five IL candidates preidentified from CAILD are further evaluated by means of process simulation using ASPEN Plus. Thereby, [C5MPy][C(CN)3] is identified as the most suitable solvent for EDS. © 2017 American Institute of Chemical Engineers AIChE J, 64: 1013–1025, 2018

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

The extractive desulfurization of thiophene (TS), dibenzothiophene (DBT), and benzothiophene (BT) in model oil was carried out using carboxylic acid-based deep eutectic solvents (DES). It was found that DES formed by formic acid as hydrogen bond donor and tetrabutylammonium bromide (TBAB) as hydrogen bond acceptor could efficiently separate organosulfur from oils. The influence parameters in this process are discussed, including extraction temperature, reaction time, mass ratio of DES to oil, multistage extraction effect, recycle times, and regeneration of DES. The results showed that the desulfurization selectivity of TBAB/HCOOH followed the order TS < BT ≈ DBT. Under the optimized conditions, the sulfur removal with BT, DBT, and TS were 81.75, 80.47, and 72% in a single stage, respectively, and after three cycles, it rose to 98.32, 98.24, and 97.6%, respectively. The sulfur content in fuels can be achieved to less than 8.4, 8.8, and 12 ppm for BT, DBT, and TS, respectively. In addition, by discussion of...

Ternary Liquid-Liquid Equilibria for Mixtures of {Ionic Liquid+Thiophene or Benzothiophene+Heptane} at T=308.15K.

In this work, the desulfurization ability of alkyl-piperidinium-based and phosphonium-based ionic liquids (ILs) for (thiophene or benzothiophene + heptane) mixtures are studied. With this aim, ternary liquid–liquid phase equilibrium data (LLE) have been obtained for mixtures of {IL (1) + thiophene, or benzothiophene (2) + heptane (3)} at T = 308.15 K and p = 101.33 kPa. For this study 1-pentyl-1-methylpiperidinium bis{(trifluoromethyl)sulfonyl}imide, [C1C5PIP][NTf2], and tributylethylphosphonium diethylphosphate, [P2,4,4,4][DEP], were used. The suitability of these ILs as solvents for extractive desulfurization has been evaluated in terms of the solute distribution ratio and selectivity. Immiscibility was observed in the binary liquid systems of (thiophene, or benzothiophene + heptane) with both ILs. One of the studied ILs, [C1C5PIP][NTf2], shows high distribution ratios and high selectivities for extraction of sulfur compounds. The data obtained have been correlated with the non-random two liquid NRTL model. The experimental tie-lines and the phase compositions in mole fractions in the ternary systems were calculated with an average root mean square deviation of 0.0052.Electronic supplementary materialThe online version of this article (doi:10.1007/s10953-014-0276-y) contains supplementary material, which is available to authorized users.

Effect of the cation and anion of the ionic liquid on desulfurization of model fuels

Ionic liquids (ILs) are known as a new solvents with high extraction capacity for aromatic sulfur and aromatic compounds from gasoline and diesel in comparison to the conventional solvents. In this work the desulfurization ability of 21 ionic liquids in the extraction of sulfur organic compounds from hydrocarbons, which were used as a model of gasoline and diesel oils by solvent extraction, has been developed. With this aim, ternary liquid–liquid phase equilibrium data (LLE) has been obtained for mixtures of {IL+model fuel (thiophene, benzothiophene, dibenzothiophene, toluene, tetralin)+heptane} at T=298.15K and ambient pressure. The ILs studied: pyridinium-, pyrrolidinium-, morpholinium-, imidazolium-, piperidinium-, phosphonium-, and ammonium-based with different anions as dicyanoamide, [DCA], tetracyanoborate, [TCB], tricyanomethanide, [TCM], bis{(trifluoromethyl)sulfonyl}imide, [NTf2], trifluorotris(perfluoroethyl)-phosphate, [FAP], trifluoroacetate, [TFA], and trifluoromethanesulfonate, [CF3SO3]. The suitability of ILs used as solvents for extractive desulfurization has been evaluated in terms of solute distribution coefficient and selectivity. Few of proposed ILs, as 1-butyl-4-methylpyridinium dicyanamide, [bmPY][DCA], 1-butyl-1-methylpyrrolidinium dicyanamide, [bmPYR][[DCA], and N-butyl-N-methylmorpholinium tricyanomethanide, [bmMOR][TCM] show high selectivities (>200) and high distribution coefficients (>1.2) for extraction of sulfur compounds. The experimental results obtained in this work are evaluated in view of the results reported in literature [1,2]. It is shown that the ionic liquids investigated in this work are able to extract sulfur in preference to toluene and tetralin. Moreover, the distribution coefficients for [bmPYR][TCM], [bmIM][TCM] and [bmPYR][TCB] ILs are the best for the extraction of thiophene, the [bmPY][DCA], [bmPYR][TCB], [bmPYR][TCM] and [bmIM][TCM] ILs have the best distribution coefficients for benzothiophene; the [bmPY][DCA], [bmPYR][TCM] and [P6,6,6,14][TCM] ILs have the best distribution coefficients for dibenzothiophene.

Effect of the alkyl side chain of the 1-alkylpiperidinium-based ionic liquids on desulfurization of fuels

In this work the desulfurization ability of three alkyl-piperidinium-based ionic liquids (PIPILs) from heptane, which is used as a model of gasoline and diesel oils, has been developed. With this aim, ternary (liquid+liquid) phase equilibrium data (LLE) have been obtained for mixtures of {PIPIL (1)+thiophene (2)+heptane (3)} at T=298.15K and ambient pressure and for the best thiophene entrainer {[PMPIP][NTf2] (1)+benzothiophene (2)+heptane (3)} at T=308.15K and ambient pressure. Three PIPILs have been studied: 1-propyl-1-methylpiperidinium bis{(trifluoromethyl)sulfonyl}imide [PMPIP][NTf2], 1-butyl-1-methylpiperidinium bis{(trifluoromethyl)sulfonyl}imide [BMPIP][NTf2] and 1-hexyl-1-methylpiperidinium bis{(trifluoromethyl)sulfonyl}imide, [HMPIP][NTf2]. The suitability of PIPILs used as solvents for extractive desulfurization has been evaluated in terms of solute distribution ratio and selectivity. Immiscibility was observed in the binary liquid systems of (thiophene, or benzothiophene+heptane) with all PIPILs used. One of proposed PIPILs, [PMPIP][NTf2] shows high selectivities and high distribution ratios for extraction of sulfur compounds. The data obtained have been correlated with the non-random two liquid NRTL model. The experimental tie-lines and the phase composition in mole fraction in the ternary systems were calculated with an average root mean square deviation (RMSD) of 0.0037.

Hexyl dimethylpyridinium ionic liquids for desulfurization of fuels. Effect of the position of the alkyl side chains

In this work, the desulfurization ability of the 1-hexyl-2,4-dimethylpyridinium bis(trifluoromethylsulfonyl)imide ionic liquid, [h 2,4mmpy][NTf 2], has been compared with that of 1-hexyl-3,5-dimethylpyridinium bis(trifluoromethylsulfonyl)imide, [h 3,5mmpy][NTf 2]. With this aim, liquid–liquid equilibrium data have been obtained for the [h 2,4mmpy][NTf 2] + thiophene + toluene, [h 2,4mmpy][NTf 2] + thiophene + hexane and [h 2,4mmpy][NTf 2] + pyridine + hexane ternary systems at 298.15 K and atmospheric pressure. The obtained data have been adequately correlated using the UNIQUAC and NRTL models. The suitability of both ionic liquids as solvents for extractive desulfurization has been evaluated in terms of solute distribution ratio and selectivity.