Separation of Aromatics using Benign Solvents (original) (raw)
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Fluid Phase Equilibria, 2012
In this work, new solvents are introduced to conduct the task of removing aromatic hydrocarbons from the feed stream to ethylene cracker. Liquid-liquid equilibrium (LLE) data for ternary systems of toluene and heptane with two newly introduced deep eutectic solvents (DESs) were estimated experimentally at 40, 50 and 60 • C and atmospheric pressure. The DESs are made from tetrabutylphosphonium bromide as salt and either ethylene glycol or sulfolane as hydrogen bond donor (HBD). The reliability of the LLE data were ascertained by applying the Othmer-Tobias and Hand correlations. The non-random two liquid (NRTL) model was used to correlate the experimental tie-lines and to calculate the phase compositions of the ternary systems. The results showed a very good agreement between calculated and experimental compositions. Further LLE data are presented to estimate the improvement of the separation by changing the salt:HBD molar ratio used to synthesize the DES at 30, 40, 50 and 60 • C. This work illustrates the possibility of applying these two DESs as solvents for this extraction task.
The current work reports the selective separation of aromatic and poly aromatic hydrocarbon (PAH) with Deep Eutectic Solvents (DES). The low cost DES are based on a mixture of a hydrogen bond donor and organic salt. The organic salt namely Methyltriphenylphosphonium bromide(MTBP) along with the hydrogen bond donor (HBD) were taken in a ratio of 1:4 to synthesize potential DES. DES were then varied based on the selection of two hydrogen bond donor namely ethylene glycol(DES1) and glycer-ol(DES2). In order to study their effectiveness, Liquid-liquid Equilibrium experiments were performed for the removal of toluene and quinoline respectively. LLE data corresponding to the ternary systems:[DES1(1) þ Toluene(2) þ Heptane(3)],[DES2(1) þ Toluene(2) þ Heptane(3)], [DES1(1) þ Quinoline(2) þ Heptane(3)] and [DES2(1) þ Quinoline(2) þ Heptane(3)] were generated at 308.15 K and atmospheric pressure. 1 H NMR analysis were then used for the quantification of both extract and raffinate phases. Distribution coefficient (b) and selectivity (S) were subsequently obtained and it was found that toluene had a poor selectivity than quinoline. The cross contamination of DES and heptane across either phases were found to be nearly zero. Further the Non-random two liquid (NRTL) and UNiversal QUAsi Chemical (UNIQUAC) thermodynamic model were used to compare the experimental tie line data. This gave an excellent fit with a root mean square deviation (RMSD) values for both models ranging from (0.28e0.31%) and (0.22e0.73%) respectively. DES1, namely Methyl-triphenylphosphonium bromide þ ethylene glycol was thus recommended as a potential solvent for the separation of aromatic and PAH component.
Journal of Molecular Liquids, 2017
A low cost Deep Eutectic Solvent (DES) is used in this work to evaluate the selective extraction of Poly Aromatic Hydrocarbons (PAH) from heptane. The DES synthesized is a combination of methyltriphenylphosphonium bromide salt and ethylene glycol as HBD at a molar ratio of 1:4. Quinoline and indoline as model PAH were then extracted from the tolueneheptane mixture at T=35°C. The Liquid-Liquid Equilibrium (LLE) data for the ternary system namely: DES (1) + indoline (2) + heptane (3) and quaternary systems; namely DES (1) + quinoline (2) + indoline (3) + heptane (4), DES (1) + quinoline (2) + toluene (3) + heptane (4) and DES (1) + indoline (2) + toluene (3) + heptane (4) were then measured at atmospheric pressure. The PAH concentrations in the system were varied from 5 to 70 wt% to understand the extraction efficiency of DES. The composition of the respective components in both extract and raffinate phases were measured by 1 H NMR technique. It was observed that all the systems followed a type-II phase behavior where a positive slope was seen towards the PAH peak. The distribution coefficient and selectively values for PAH in extract phase were two times higher than toluene. The reliability of the measured tie line data was then correlated with the local thermodynamic models namely NRTL and UNIQUAC models which gave a root mean square deviation (RMSD) of less than 1%. Further, Quantum chemical based COnductor like Screening MOdel for Real Solvents (COSMO-RS) model was also employed to predict the phase behaviour of investigated systems.
Applied Petrochemical Research, 2021
A suitable green solvent for extraction of aromatics from aliphatics must possess good solvation and physicochemical properties, a rare occurrence in a single deep eutectic solvent (DES). Mixture of DESs could enable synergy and provide a good candidate extractant. In this study, DESs of glyceline, ethaline, and reline were synthesized and their binary mixtures (glyceline/ethaline, reline/ethaline, and glyceline/reline) produced by blending in various volume proportions. Twelve of such mixed solvents were prepared and their extraction efficiency for separating benzene from n-hexane investigated in a batch equilibrium process. Liquid–liquid equilibria (LLE) data for the pseudo-ternary systems of n-hexane + benzene + mixed DESs were measured at 303 K and 101.3 kPa. The distribution coefficient (D) and selectivity (S) of each pseudo-ternary system were determined to elicit extraction efficiency. The physicochemical properties of the mixed DESs were also measured. The results show that ...
Ionic Liquids - Recent Progress in Synthesis, Characterization and Application [Working Title]
Ionic liquids have been proposed as separation agents for liquid extraction of aromatic compounds from their mixtures with alkanes, with the aim of improving the separation process and replacing conventional organic solvents. A significant number of experimental liquid-liquid equilibrium data for ternary system alkane + aromatic compound + ionic liquid can be found in literature; however there are few data for quaternary or higher systems involving more than one aliphatic compound, several aromatic compounds or a mixture of ionic liquids as separation agent. These data are also necessary because molecular interactions between the compounds in the mixture can modify the affinity of the solvent for the aromatic compound of interest. In this chapter we review the published data involving more than three components, and we present new liquid-liquid equilibrium data for the quaternary systems heptane + cyclohexane + toluene +1-ethyl-3-methylimidazolium bis{(trifluoromethyl)sulfonyl}imide and heptane + cyclohexane + toluene + 1-hexyl-3-methylimidazolium bis{(trifluoromethyl)sulfonyl}imide.
Fluid Phase Equilibria, 2017
The extraction of aromatic hydrocarbons from reformer and pyrolysis gasolines is currently performed by liquid-liquid extraction using organic solvents. Deep eutectic solvents (DES) are being widely studied as environmentally benign alternatives to conventional solvents since DES can be prepared using nontoxic and renewable chemicals. In this work, we have studied for the first time the application of DES in the extraction of aromatic hydrocarbons from reformer and pyrolysis gasolines. We have tested six choline chloride-based DES formed by ethylene glycol, glycerol, levulinic acid, phenylacetic acid, malonic acid, and urea as hydrogen bond donors. COSMO-RS method was employed to predict the performance of the DES in the extraction of aromatics, whereas experimental results indicate that DES formed by choline chloride and levulinic acid has exhibited the most adequate extractive and physical properties. Afterward, the simulation and optimization of the whole process for extraction of aromatics, recovery of extracted hydrocarbons, and regeneration of the solvent have been performed. The proposed process of dearomatization could work at moderate temperatures using a cheap, sustainable, and nontoxic solvent.
2019
The separation of benzene and cyclohexane is difficult to perform via conventional distillation because of their close boiling points. The use of conventional technology in industry suffers from several disadvantages such as process complexity, high capital and operating costs, and high energy consumption. Ionic liquids (ILs) and deep eutectic solvents (DESs) are two types of emerging solvents being widely studied in many applications. In this study, 40 DESs and more than 200 ILs were separately screened using COSMO-RS program for the separation of benzene and cyclohexane by liquid–liquid extraction process. The screening was evaluated based on the comparison of selectivity, capacity, and performance index; all derived from the activity coefficient at infinite dilution. The actual performance of the top-screened solvents, i.e. 5 DESs and 4 ILs was validated via experimental liquid–liquid extraction process at 25 oC and under 1 atm. The selected DESs in this study, namely tetrabutyla...
Fluid Phase Equilibria, 2012
In this work we studied the applicability of one ionic liquid analogues namely phosphonium based deep eutectic solvent (DES) in the extraction of aromatic hydrocarbons from aromatic/aliphatic mixtures. Experimental data for liquid-liquid equilibria (LLE) were obtained for various mixtures of (benzene + hexane + DES) at 27, 35 and 45 • C. Some of the mixtures showed excellent results in terms of aromatic selectivity and distribution ratio compared to what is currently used in industry. Chromatography analysis showed that the ethylene glycol used in forming the deep eutectic solvent was not present in the raffinate layer. This eliminates the step needed for the separation of the solvent. A comparative study of the separation effectiveness of the DES in this work with other reported ionic liquids as well as sulfolane was performed for choosing the best solvent for the intended separation. .my (M.A. Hashim), alnashef@ksu.edu.sa (I.M. AlNashef).
Selective Aromatics extraction from hydrocarbon mixtures
This work is aimed at the study of liquid-liquid equilibrium of systems of industrial interest, particularly the purification of oil and gas in the oil refining industry. We present experimental results on the solubility of aromatics in the liquid-liquid equilibrium obtained by gas -liquid chromatography at different temperatures. We used a mixture of solvents to improve the characteristics of selectivity and aromatics extraction. The solvent is a binary mixture of N-methyl 2-pyrrolidone (NMP) and diethylene glycol (DEG). The results presented are for two mixtures consisting of 90% NMP + 10% DEG, and 70% NMP +30% DEG. Heptane was used as hydrocarbon solvent and toluene as aromatic compound. Furthermore, we applied the equation of state NRTL (Non Random Two Liquids) and UNIQUAC (Universal Quasi Chemical) for coexistence curves and the critical point.
Deep Eutectic Solvents for the Separation of Toluene/1-Hexene via Liquid–Liquid Extraction
Separations
The separation of aromatic/olefin mixtures is a difficult task in the petrochemical industry, since the boiling points of these hydrocarbons are very similar. This work aims to use deep eutectic solvents (DESs) for the extraction of toluene from 1-hexene by liquid–liquid extraction. A total of 53 DESs were studied qualitatively and quantitatively using the COSMO-RS approach to separate the binary mixture of toluene and 1-hexene. The selectivity, capacity, and performance index of all DESs were evaluated by calculating the activity coefficient at infinite dilution. The σ-profile and σ-potential of each component were interpreted to evaluate the interactions between the different species. We then selected three DESs for experimental validation, namely benzyltriphenylphosphonium chloride:triethylene glycol BzTPPCl:TEG (1:8), tetrabutylammonium bromide:triethylene glycol TBABr:TEG (1:3), and tetrabutylammonium bromide:ethylene glycol TBABr: EG (1:4). Experimental liquid–liquid equilibri...