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Heat integration by pinch method is used to modify the heat exchanger network of an industrial ethylene glycol plant. The aim is to reduce the energy cost by operating the plant close to the maximum energy recovery. Pinch analysis identified a pinch temperature of 483 K, a minimum heating utility of 13,490.9 MJ/ton EO, and a minimum cooling utility of 25,697 MJ/ton EO. Using the pinch decomposition diagram and the standard procedure for matching hot and cold streams, a retrofit of the heat exchangers network is developed. The modified heat exchanger network reduces the external cooling duty by 45.5% and the external heating duty by 93.3%. This promising cost savings provide enough justification for restructuring the existing ethylene glycol plant. Moreover, an additional 6% reduction in the external cooling duty can be achieved by integrating the steam turbine below the pinch point.

Solid-liquid equilibria (SLE) of binary mixtures of several n-alkanes (n-octadecane, n-eicosane, n-tetracosane, n-pentacosane, n-triacontane) and dibenzofuran covering the whole composition range were measured by differential scanning calorimetry (DSC) in a temperature range of 301-356 K. The dibenzofuran and the n-alkanes are completely miscible in the liquid state but non-miscible in the solid-state, and in the context of this work, they seem to exhibit eutectic behavior. A linear trend is obtained for the eutectic temperature and eutectic composition versus the number of carbon atoms of n-alkane. The experimental data were compared to predictions made by using the ideal solution model, the DISQUAC model and several versions of the UNIFAC model, including the classical UNIFAC, the modified versions of Lyngby and Dortmund, and the recently proposed modified UNIFAC (NIST) model, to account for non-ideality in the liquid phase. Moreover, the experimental data were also compared with COSMO-RS predictions that utilize quantum chemical calculations and statistical thermodynamics to interpret the behavior of molecular interactions in the binary mixture. A good agreement was obtained between the predicted and the experimental temperatures.

The energy efficiency of an absorption–desorption system for carbon dioxide capture from flue gas utilizing methyltriphenylphosphonium bromide-monoethanolamine (MEA) deep eutectic solvent is investigated in this article. According to the results, when the working pressure of the absorber column increases, the process becomes significantly exergy deficient, with an exergy loss of 7.63 MW compared to 5.7 MW for a normal MEA process. The majority of the exergy deficit is due to flue gas compression effort, which accounts for 99% of the total process exergy. The process’s exergy shortfall can be improved by lowering the absorber pressure from 10 to 3 atm, lowering the carbon dioxide removal efficiency from 90% to 60%, and increasing the solvent-to-gas ratio from 075 to 7.05. Furthermore, the incorporation of an energy recovery device could allow for an 80–90% reduction in the energy consumed by the gas compressor when running at 10 atm, from 5.7 to 1.2 MJ‧kg CO2 −1. With this adjustment, the deep eutectic solvent-based process can match or outperform the corresponding aqueous alkanolamine solvent-based process in terms of exergy destruction and specific energy consumption.

Deep eutectic solvents (DESs) are efficient media for CO

Four different dicyanamide-based ionic liquids (ILs), [Cnmpy][DCA] (n = 4, 6, 8, and 10), were synthesized, characterized, and used to separate ethylbenzene from n-octane. Equilibrium data for the corresponding ternary systems were measured at 313.15 K under atmospheric pressure. A higher selectivity is observed for lower aromatic concentrations in the feed (20% max); this is a key factor in selecting a suitable IL. The distribution ratio and selectivity obtained in this work are comparable to those of commercial solvents. The nonrandom two-liquid model (NRTL) was successfully used to correlate the experimental tie-lines and to calculate the phase compositions of the ternary systems. Moreover, the antimicrobial activities of the ILs were evaluated by examining their 50% effective concentrations (EC50) using the standard microbroth dilution test against four human bacterial pathogens. 1-Butyl 3-methylpyridinium dicyanamide [C4mpy][DCA] was found as the most suitable IL among those investigated because of i...

Ionic liquids (IL) are considered viable alternative solvents for CO2 capture. Because of this and the unlimited number of possible combinations between cations and anions, it is important to devel...

Chlorophenols (CPs) are synthetic chemicals that are generated and used widely by different industries such as textile, pharmaceutical, metallurgic, oil, and pulp and paper manufacturing. Except water, most of the solvents used in these industries are volatile and toxic. Therefore, there is an imminent need for replacing these solvents by solvents that have less negative impact on the environment. In addition, CPs are considered as hazardous pollutants due to their resistance to biodegradation and persistence in the environment. Their toxic effects are severe including DNA damage, endocrine disruption, cytotoxicity, mutagenicity, and carcinogenicity. Hence, the water contaminated by CPs must be treated before being released to the environment. Ionic liquids (ILs) are molten salts that are liquid below 100 °C, which have been used as solvents for many processes including liquid-liquid extraction and as electrolytes in electrochemical devices. ILs are characterized by negligible vapor pressure and non-flammability. These compounds are liquid over a wide range of temperatures; possess high thermal and chemical stability. ILs are being used as media for many reactions to reduce the negative impact of traditional solvents on the environment. In addition, using ILs as green solvents in water treatment has become a research hotspot. Solubility data of CPs in ILs is important for assessing the potential use of ILs as reaction media and in water treatment, but relevant data for ILs are scarce. To our best knowledge, no solubility data of chlorophenols in ILs were reported in the literature. Thus, in this study, the solubility of 3-chlorophenol (3-CP), 2,5-dichlorophenol (DCP), 2,4,6-trichlorophenol (TCP), and pentachlorophenol (PCP) in six hydrophobic bis(trifluoromethylsulfonyl)imide based ILs at 25 °C, 35 °C and 45 °C was investigated. It was found that the solubility of 3-CP in all studied ILs at 25 °C was greater than 70 wt%, thus the solubility measurements of 3-chlorophenol in the studied IL were stopped at 70 wt% and further measurement was not conducted. The solubility of other CPs in all studied ILs decreased with increasing the number of chlorine atoms in the CP and increased with the increase in temperature, but the degree of increase depended on the structure of both the IL and chlorinated phenol. In general, it was found that the tested chlorophenols have substantial solubility in pyridinium and imidazolium-based ILs. In addition, the non-random two-liquid model (NRTL) and Conductor-like Screening Model for Real Solvents (COSMO-RS) models were applied to predict the solubility of chlorophenols in all ILs used in this study. There was a good quantitative and qualitative agreement between experimental and calculated solubility data in most of the cases.

Separation of styrene from ethylbenzene is challenging because of their close boiling points and similar chemical characteristics. In this study, we utilized three ammonium-based deep eutectic solvents (DESs) with glycols as hydrogen bond donors to separate styrene from ethylbenzene via liquid-liquid extraction at room temperature and atmospheric pressure, with styrene concentration in the feed mixture ranging from (10 to 80) wt%. Consistency of the experimental data was ascertained by Othmer-Tobias and Hand correlations, and the NRTL binary interaction parameters were also validated for thermodynamic consistency. Distribution ratios of styrene were found to be comparable to that obtained using ionic liquids, although the selectivity values were much lower. The ternary liquid-liquid equilibria for the systems {ethylbenzene (1) + styrene (2) + DES (3)} were correlated with the NRTL model and predicted using the COSMO-RS approach. The average RMSD from the experimental data for NRTL correlation is 1.41% and for COSMO-RS prediction is 4.74%.

The separation of benzene and cyclohexane is a challenging process in petrochemical industry due to their close boiling points. Solvent mixing is a useful technique to enhance the extraction performance of liquid–liquid extraction process. In this work, the performance of solvent mixtures involving two organic solvents (N,N-dimethylformamide and ethylene glycol) and four ionic liquids (ILs), namely, 1-ethyl-3-methylimidazolium thiocyanate (C2mimSCN), 1-ethyl-3-methylimidazolium dicyanamide (C2mimN(CN)2), 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (C2mimTf2N) and 1-ethyl-3-methylimidazolium acetate (C2mimAc) was investigated for the extractive separation of benzene and cyclohexane. The mixing ratios of the binary solvents were optimized using the ideal mixing calculation and validated experimentally through liquid–liquid extraction process. Six new quaternary liquid–liquid equilibria for the mixed solvents with benzene and cyclohexane were investigated at 25 °C and 1 atm, with feed concentrations of benzene ranging from 10 to 50 wt%. Ethylene glycol was discovered a good solvent pair with C2mimTf2N that could lead to potential cost savings. At the optimized mixing fraction, the {C2mimTf2N + C2mimSCN} mixture demonstrated the highest extraction performance, which was superior to that of sulfolane. Additionally, the {C2mimSCN + C2mimN(CN)2} and {C2mimN(CN)2 + C2mimAc} mixtures were found to increase the selectivity while maintaining the benzene distribution ratio in relation to sulfolane. The ILs were not present in the raffinate layer of any of the systems, indicating the reliable performance of the ILs in terms of avoiding solvent cross-contamination. This work demonstrated the use of binary solvent mixtures as a new efficient and versatile method to enhance extraction performance.

The oxidative coupling of methane (OCM) process is considered an intriguing route for the production of ethylene, one of the most demanded petrochemical products on the market. Ethylene can be produced by various methods, but the most widely used is the steam cracking process. However, due to the current instability of the crude oil market and the shale gas revolution, the production of olefins from natural gas has opened a new path for companies to mitigate the high demand for crude oil while utilizing an abundant amount of natural gas. In this work, the OCM process was compared with other existing processes, and the process was simulated using Aspen HYSYS. The flowsheet was divided into four sections, namely (i) the reaction section, (ii) the water removal section, (iii) the carbon dioxide capture section, and (iv) the ethylene purification section. Each section was thoroughly discussed, and the heat integration of the process was performed to ensure maximum energy utilization. The heat exchanger network was constructed, and the results show that the heating utility can be reduced by more than 95% (from 76567 kW to 2107.5 kW) and the cooling utility can be reduced by more than 60% (from 116398 kW to 41939.2 kW) at an optimum minimum temperature difference of 25 °C. In addition, a case study on the recovery of the high exothermic heat of reaction for power production shows that 16.68 MW can be produced through the cycle, which can cover the total cost of compression.

Deep eutectic solvents (DESs) are green solvents developed as an alternative to conventional organic solvents and ionic liquids to extract nitrogen compounds from fuel oil. DESs based on p-toluenesulfonic acid (PTSA) are a new solvent class still under investigation for extraction/separation. This study investigated a new DES formed from a combination of tetrabutylphosphonium bromide (TBPBr) and PTSA at a 1:1 molar ratio. Two sets of ternary liquid&ndash, liquid equilibrium experiments were performed with different feed concentrations of nitrogen compounds ranging up to 20 mol% in gasoline and diesel model fuel oils. More than 99% of quinoline was extracted from heptane and pentadecane using the DES, leaving the minutest amount of the contaminant. Selectivity was up to 11,000 for the heptane system and up to 24,000 for the pentadecane system at room temperature. The raffinate phase&rsquo, s proton nuclear magnetic resonance (1H-NMR) spectroscopy and GC analysis identified a significantly small amount of quinoline. The selectivity toward quinoline was significantly high at low solute concentrations. The root-mean-square deviation between experimental data and the non-random two-liquid (NRTL) model was 1.12% and 0.31% with heptane and pentadecane, respectively. The results showed that the TBPBr/PTSADES is considerably efficient in eliminating nitrogen compounds from fuel oil.

Deep eutectic solvents (DESs) are green solvents developed as an alternative to conventional organic solvents and ionic liquids to extract nitrogen compounds from fuel oil. DESs based on p-toluenesulfonic acid (PTSA) are a new solvent class still under investigation for extraction/separation. This study investigated a new DES formed from a combination of tetrabutylphosphonium bromide (TBPBr) and PTSA at a 1:1 molar ratio. Two sets of ternary liquid–liquid equilibrium experiments were performed with different feed concentrations of nitrogen compounds ranging up to 20 mol% in gasoline and diesel model fuel oils. More than 99% of quinoline was extracted from heptane and pentadecane using the DES, leaving the minutest amount of the contaminant. Selectivity was up to 11,000 for the heptane system and up to 24,000 for the pentadecane system at room temperature. The raffinate phase’s proton nuclear magnetic resonance (1H-NMR) spectroscopy and GC analysis identified a significantly small amount of quinoline. The selectivity toward quinoline was significantly high at low solute concentrations. The root-mean-square deviation between experimental data and the non-random two-liquid (NRTL) model was 1.12% and 0.31% with heptane and pentadecane, respectively. The results showed that the TBPBr/PTSADES is considerably efficient in eliminating nitrogen compounds from fuel oil.

An optimal ratio of omega-6 to omega-3 (ω-6/ω-3) polyunsaturated fatty acids (PUFA) in the diet prevents the pathogenesis of many inflammatory diseases. This study aimed to synthesize and characterize ternary oil blends with optimal ω-6/ω-3 ratios using olive (OL), sunflower (SU), and cress (CR) oils. The oxidative stability, thermal profile, fatty acid (FA) and tocopherol compositions, and the physicochemical properties of the blends were used to determine their quality. Oil mixtures were prepared with 2, 3, 4, and 5 ω-6/ω-3 ratios. FA composition and tocopherol content were the most important factors affecting the oxidation and thermal stabilities of the oils. All oil mixtures showed good quality indices. Thus, synthetized oil blends with high oxidative stability, high antioxidant content, optimal ω-6/ω-3 ratios, and recommended FA compositions can influence human health. The composition of healthy oil blends with optimal ω-6/ω-3 ratios was expressed mathematically and depicted graphically in a ternary diagram.

The separation of benzene and cyclohexane from their mixture is difficult to perform via conventional distillation because of their close boiling points. In this work, liquid-liquid extraction using ionic liquids (ILs) is suggested for this purpose and 16 cations and 13 anions were selected to form 208 possible ILs screened with the Conductor-like Screening Model for Real Solvents (COSMO-RS) module. The screening result was experimentally validated by liquid–liquid extraction using four of the top ranked ILs, namely 1-ethyl-3-methylimidazolium acetate ([C2mim][Ac]), 1-ethyl-3-methylimidazolium dicyanamide ([C2mim][N(CN)2]), 1-ethyl-3-methylimidazolium thiocyanate ([C2mim][SCN]) and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C2mim][Tf2N]). The ternary liquid–liquid equilibria for these ILs with benzene and cyclohexane were investigated at 25 °C and 1 atm with feed concentration of benzene ranging from 10 to 60 wt%. Good agreement was achieved between the tie-lines obtained from the COSMO-RS model and those obtained experimentally. The performance of ILs used in this study was compared with organic solvents, other ILs, and deep eutectic solvents reported in literature. The results of selectivity and distribution ratio confirmed that COSMO-RS was a reliable method for solvent screening and demonstrated the suitability of the selected ILs as extracting solvents. In all ternary systems, no IL was detected in the cyclohexane layer and the concentration of cyclohexane in the IL layer was very low. This observation indicated that there was minimum cross-contamination between the phases and therefore less energy will be required for the solvent recovery.

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][MeSO3]) ionic liquid in removing pyrrole, indoline, pyridine and quinoline from cyclohexane is investigated. The ternary liquid-liquid equilibria for four systems containing [Emim][MeSO3] + 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][MeSO3] as an extraction solvent for removing nitrogen compounds from fuel. Finally, the multicomponent extraction confirmed the performance of [Emim][MeSO3] 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.

Styrene is a valuable commodity for polymer industries. The main route for producing styrene by dehydrogenation of ethylbenzene consumes a substantial amount of energy because of the use of high-temperature steam. In this work, the process energy requirements and recovery are studied using Exergy analysis and Heat Integration (HI) based on Pinch design method. The amount of steam plays a key role in the trade-off between Styrene yield and energy savings. Therefore, optimizing the operating conditions for energy reduction is infeasible. Heat integration indicated an insignificant reduction in the net energy demand and exergy losses, but 24% and 34% saving in external heating and cooling duties, respectively. When the required steam is generated by recovering the heat of the hot reactor effluent, a considerable saving in the net energy demand, as well as the heating and cooling utilities, can be achieved. Moreover, around 68% reduction in the exergy destruction is observed.

In this study, the COSMO-RS approach was used to qualitatively and quantitatively screen five choline chloride-based deep eutectic solvents (DESs) to separate the azeotropic binary formed between benzene and either methanol or ethanol. The activity coefficient at infinite dilution was calculated to evaluate the capacity, selectivity, and performance index of each DES. The interactions between the different species were also analyzed by interpreting the σ-profile and σ-potential of each component. Then, three DESs were selected for experimental validation. They were prepared by combining choline chloride with ethylene glycol, levulinic acid, and 1,2-propanediol. The best performance in terms of distribution ratio and selectivity was achieved with choline chloride/ethylene glycol DES with 1:4 molar ratio. The experimental tie-lines were successfully correlated using the NRTL model. Regardless of the system investigated, no DES was found in the raffinate phase, implying minimal cross-contamination. Finally, ...

In this study, the feasibility of twelve different deep eutectic solvents (DESs) in separating olefins from paraffins was investigated. The DESs were prepared by combining choline chloride (ChCl) or tetrabutyl ammonium bromide (TBAB) with six different hydrogen bond donors. The preliminary COSMO-RS screening revealed that TBAB/TEG (1:4) DES has the high performance index (PI) for both systems. This performance was confirmed by experimental tests at 20% molar ratio of olefins in the feed mixture with the twelve DESs. When TBAB is used, the best distribution ratios were obtained for cyclohexane/cyclohexene system, however for hexane/1-hexene system high selectivities were gotten. In comparison with the performance of ionic liquids, TBAB-based DESs showed better distribution ratios and comparable selectivity. For the cyclohexane/cyclohexene system, TBAB-based DESs exhibited high distribution ratios because of their hydrophobic character represented by butyl chain. In the case of hexane/1-hexene system, TBAB-based DESs are more selective to 1-hexene due to the affinity of TBAB chain and positive charge bringing by ammonium group and 1-hexene. The liquid–liquid equilibrium (LLE) was explored for two ternary systems of {hexane (1) + 1-hexene (2) + DES (3) } and {cyclohexane (1) + cyclohexene (2) + DES (3) } at 298.15 K and 101 kPa using TBAB/TEG (1:4) DES. Furthermore, the NRTL model was successfully used to correlate the experimental LLE data and good predictions were obtained with COSMO-RS for both selected systems. Finally, the extraction mechanism was elucidated by applying 1H NMR analysis and no DESs were found in the raffinate phase.

Eutectic solvents (ESs) have been extensively studied in the literature for the purification of fuels. Nevertheless, most studies investigated the extraction of a single type of aromatic from n-alkanes. In this work, aiming to provide insights about the performance of ESs in a process that mimics the multicomponent dearomatization used industrially, a salt-acid-based ES, comprised of methyltriphenyl-phosphonium bromide and acetic acid, was applied in simultaneously extracting toluene, thiophene, quinoline, and pyrrole from n-decane. First, the DES was characterized for its eutectic composition, physicochemical, and critical properties. Then, an initial screening to determine the molecular-level interactions and extraction mechanism were studied experimentally and using COSMO-RS screening charge density profiles and potentials. A physical mechanism was confirmed for the extraction of pyrrole, thiophene, and toluene while for quinoline, an acid-base reaction was the predominant extraction mechanism. The phase diagrams of each impurity were also experimentally determined, predicted using the COSMO-RS model, and correlated using the NRTL model in Aspen Plus. Lastly, a parametric investigation studying the impact of key parameters including stirring time, initial concentration, mixing effects, solvent-to-feed ratio, multi-stage extraction, and repetitive usage of solvent was conducted. On multi-stage extraction, full recovery of pyrrole and quinoline ( ≈ 99.9%) was achieved in only 2-stages, whereas for thiophene and toluene efficiencies of 82.2% and 58.4% were reached after the 5th stage, respectively.

The solid–liquid equilibria (SLE) phase diagrams have been determined using a DSC technique for dibenzofuran + n-C21, or + n-C31, or + n-C41 mixtures. The three systems show a eutectic point. Values of the eutectic temperature and of the heat of melting have been also evaluated and used to determine the eutectic composition of the systems by means of the Tamman’s plots. The dependence of deviations from ideality of dibenzofuran + aromatic hydrocarbon mixtures with size, shape, and of the degree of alkylation of the hydrocarbon has been investigated. At this end, we have considered SLE data available in the literature for solutions including benzene, acenaphthene, phenanthrene, anthracene, biphenyl, chrysene, toluene, or diphenylmethane. Dibenzofuran + n-alkanes systems show positive deviations from the ideal solution model, which increase with the alkane size. The mentioned deviations are stronger in the corresponding xanthene solutions. DISQUAC interaction parameters have been obtained for the (aromatic/ether) and (aliphatic/ether) contacts in dibenzofuran or xanthene + aromatic hydrocarbon, or + n-alkane mixtures. Better fitting is obtained with DISQUAC model compared to the Ideal Solubility Model, or UNIFAC model. Finally, the COSMO-RS model was used to predict the eutectic coordinates for the binary systems Dibenzofuran + n-alkanes (n-C21, or n-C31 or n-C41). Excellent agreement was obtained only for the eutectic temperature.

The increasing demand for multi-task green solvents has spurred the development of next-generation liquid media such as deep eutectic solvents (DESs), which have recently attracted increased attention. DESs are mixtures of salts and complexing agents, having freezing points lower than those of starting individual components. Similarly to ionic liquids, DESs exhibit distinctive properties such as chemical and thermal stability, biodegradability, non-flammability, and cost effectiveness. These features account for their wide range of applications, e.g. as extractants, reactants, catalysts, reaction media, additives, and lubricants. This review summarizes the recent research efforts directed at exploring the potential applications of DESs in various chemical processes. With the rapid publication of reports on this new generation of solvents, other roles also are expected to be seen sooner or later. © 2017 Society of Chemical Industry

The reported experimental data for the separation of aromatic from aliphatic compounds using green solvents is growing exponentially. This paper surveys the existing data and presents a critical review that helps clarifying the major findings, identifies shortcomings and provides some recommendations. The comparison between deep eutectic solvents (DESs) and both ionic liquids (ILs) and classical organic solvents for this challenging separation is also presented based on experimental selectivity and distribution ratio data. This comparison confirms the capability of DESs to effectively extract aromatic compounds and shows that DESs can compete with ILs and even outclass them in some cases. Moreover, our comprehensive literature survey has revealed that in many cases the use of DESs yields to a minimum cross-contamination between the two phases. This will undeniably facilitate the separation procedure and thus reduce the cost of the separation process. On the other hand, the performance of COSMO-RS to predict ternary liquid-liquid equilibrium diagrams for systems including DESs is also evaluated in this work for all available data. COSMO-RS was able to reproduce the experimental tie-lines with a good accuracy in many cases. Therefore, it represents a cost-effective and time-saving screening tool to evaluate the extraction performance of the unlimited number of possible salt/complexing agents' combinations.

Separation of azeotropic mixtures is a topic of great industrial interest. In this work, liquid-liquid extraction using deep eutectic solvents (DESs) is explored to separate binary azeotropic mixtures of ethanol and n-hexane, n-heptane or n-octane. Ten DESs were screened using the COSMO-RS approach by predicting the activity coefficient at infinite dilution, γ∞ of ethanol and n-alkanes in each DES. Then, three DESs were selected for experimental validation where Tetrabutylammonium bromide/Levulinic acid (TBAB/LA) with a molar ratio (1:2) gave the best extractive performance for all systems. Ternary liquid-liquid extraction experiments were conducted at room temperature with this DES. It was found that the tie-lines of all systems have positive slopes, indicating that a small amount of solvent is required to extract ethanol. Moreover, the distribution ratio and selectivity values are all greater than unity and the DES was not detected in the raffinate phase which indicate minimal cross-contamination between extract and raffinate phases. Finally, COSMO-RS predictions of the ternary tie-lines were in excellent agreement with experimental data, with an average RMSD value of 1.65%. The experimental data were also successfully correlated with NRTL model with an average RMSD value of 1.50%.

In the search for greener solvents to replace the commercially organic volatile solvents that caused negative impact on both human beings and the environment, researchers investigated a number of potential alternatives, e.g. ionic liquids (ILs), supercritical CO2, deep eutectic solvents (DESs), etc. DESs are mixtures of two or more compounds that due to interaction forces have melting points less than that of any of their constituents. With the wise selection of their constituents, DESs can have attractive physiochemical properties, e.g. low volatility, high thermal stability, moderate electrical conductivity, extremely low toxicity, and biodegradability. In addition, the DESs' properties could be tuned by selecting constituents with suitable chemical structures and by changing the molar ratio of the constituents. In this review, we investigated the main differences between two important classes of DESs, namely, ammonium and phosphonium based DESs. We focused our interest on the effect of both DES structure on physiochemical properties, such as density, viscosity, surface tension, electrical conductivity, freezing temperature and thermal stability, as well as their respective performance in selected applications. Mainly, it was found that in most cases the ammonium based DESs have more favorable properties compared to their phosphonium counterparts, e.g. lower melting point and lower viscosity. However, there was no clear trend for the performance of these DESs in the applications reported in the literature. Finally, we discussed the main challenges and limitations that must be taken into consideration before using DESs industrially.

The separation of benzene and cyclohexane is considered one of the most challenging processes in the petrochemical industry. For this study, 40 deep eutectic solvents (DESs) were screened by using the COSMO-RS model. The screening was achieved based on a comparison of selectivity, capacity, and the performance index, all derived from the activity coefficient at infinite dilution. In addition, the sigma σ-profile and σ-potential of each component were used to analyse the interactions between the different species during the extraction process. After screening, five DESs were selected for experimental validation. The liquid–liquid extraction process was conducted, and the ternary diagrams were plotted for the selected DESs at 25 °C under atmospheric pressure. The NRTL model was successfully employed to correlate the experimental tie lines. The results revealed that COSMO-RS was a useful tool for screening potential DESs qualitatively. In addition, observations revealed strong agreement between NRTL and the experiment results, with a root mean square deviation of less than unity for all systems. The findings showed that the selected DESs are feasible for use as extracting solvents for this separation, whereby in all systems no trace of DES was found in the cyclohexane layer.

This study explores the use of COSMO-RS model and Peng-Robinson (PR) equation of state (EoS) to predict the solubility of carbon dioxide (CO2) in specific ionic liquids (ILs). COSMO-RS was employed to estimate of CO2 solubility at atmospheric pressure in eight imidazolium-based ILs resulting from the combination of ethyl, butyl, hexyl, and octyl-imidazolium cations with two anions: bis(trifluoromethylsulfonyl)imide ([Tf2N]) and Trifluoromethanesulfonate ([TFO]). The results indicated relatively acceptable qualitative consistency between the experimental and predicted values. The PR EoS was employed at high pressure by tuning the interaction parameters to fit the experimental data reported in the literature. The model demonstrated excellent accuracy in predicting the solubility of CO2 at pressure values less than the critical pressure of CO2; however, at higher pressures, the calculated solubility diverged from the experimental values. Furthermore, the type of anion and cation used in the IL affected the p...

This study aims to investigate the temperature dependence of the physicochemical properties of five cations paired with bis(trifluoromethylsulfonyl)imide anion, namely 1-(2-methoxyethyl)-1-methylpiperidinium bis(trifluoromethylsulfonyl)imide, 1-(2-methoxyethyl)-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide, N-methoxyethyl-N-methylmorpholinium bis(trifluoromethylsulfonyl)imide, N-ethyl-N,N-dimethyl-2-methoxyethylammonium bis(trifluoromethylsulfonyl)imide and ethyl-dimethyl-propylammonium bis(trifluoromethylsulfonyl)imide. The density, viscosity, conductivity and surface tension of the resulting ionic liquids (ILs) have been determined within the temperature range (298.15–353.15) K. It has been found that all ILs exhibited Arrhenius behavior for conductivity and viscosity while the surface tension and density followed a linear trend. A satisfactory agreement was obtained between our experimental densities and those predicted by the group contribution model. This study is essential in the application of these ILs for process design and will reinforce the development of new correlations and other predictive methods in particular when the physicochemical properties are scarce, like in the case of morpholinium-based ILs.

For the practical application of ionic liquids as possible solvents for the removal of thiophenic compounds in the diesel fuel, the liquid–liquid equilibrium (LLE) data of such systems is necessary for the design and optimization of process equipment. In this work, LLE experiments were carried out on four ternary systems consisting of one of two pyrrolidinium or phosphonium-based ionic liquids (IL), one of two sulfur compounds and hexadecane as a representative for diesel fuel. For benzothiophene, the system consisting of the [HMPyrr][TFSI] IL as a solvent possesses the highest solute distribution coefficient (2.754) while a solute distribution coefficient of 3.722 was recorded for dibenzothiophene using the [P4444][MeSO3] as an extraction solvent. The LLE data were fairly correlated with the NRTL model especially at the region of low mole fraction of the sulfur compounds. The data presented in this work can therefore be integrated into process simulators and can be used for preliminary techno-economic evaluation of an ionic liquid-based deep extractive desulfurization of diesel fuel.

This work investigates the use of deep eutectic solvents (DESs) to extract sulfur-based compounds from n-heptane as model diesel compounds. Four DESs were prepared by combining tetrabutylammonium bromide or methyltriphenylphosphonium bromide with ethylene glycol, triethylene glycol, or sulfolane. All DESs showed good ability to extract thiophene with the best extraction efficiency (35%) being observed for the sulfolane-based DES. The extraction efficiency can be further enhanced to reach 98% when five extraction cycles are performed. Moreover, the DESs were easily regenerated using rotary evaporation. In addition,1H NMR analysis is used to elucidate the extraction mechanism. Finally, the COSMO-RS model was used to predict the ternary tie lines for the studied systems and the NRTL model allowed, correlating the experimental data with an average root-mean-square deviation of

Selected types of deep eutectic solvents (DESs) were compared for designing CO 2 capturing process. Specifically, the typical absorption–desorption process is examined. A mathematical model based on Peng–Robinson equation of state was developed to estimate the CO 2 solubility and to determine the VLE conditions in the desorption unit. The comparison of the DES performance is based on the solvent requirement in the absorption unit and the temperature condition in the desorption unit. Ethanol amine based DES has shown the best performance when operating the absorber at 10 bar and the stripper at 1 bar. However, the simulation results indicate that in order to reduce the energy requirements in the regeneration process a large amount of solvent is needed. In fact, for 80% CO 2 recovery the solvent intake rate should be at least 5 times the flue gas flow rate. Finally, we have shown that (i) the desorption energy required with MEA based DESs is much lower compared to the classical MEA process and that (ii) the energy required for compression remains the most important drawback for a such process, especially at low CO 2 concentrations.

Recently, we published the results of screening the performance of 94 deep eutectic solvents (DESs) by COSMO-RS for potential use in the extractive denitrogenation of diesel. In this work and based on our previous predictions, tetrabutylammonium bromide + ethylene glycol and tetrabutylphosphonium bromide + ethylene glycol DESs at molar ratio 1:2 were explored experimentally for the removal of pyrrole, pyridine, indoline and quinoline from a model diesel compound, n-hexadecane. Ternary (liquid + liquid) equilibrium experiments were conducted at room temperature with nitrogen concentrations in the feed ranging from (5 to 50) wt%. 1H NMR spectroscopy was used for compositional analysis of the extract and raffinate phases. No amount of the solvent in the raffinate phases was detected; indicating minimal cross contamination. Also, it was found that all systems exhibit Type I phase behavior with positive slopes which indicate that small amount of solvents is required to remove the nitrogen compounds. Moreover, the distribution ratio and selectivity values are all greater than unity with higher values reported for non-basic nitrogen compounds. COSMO-RS predictions of the ternary tie lines were in good agreement with experimental data with average RMSD value of 2.51%. The experimental data were also well correlated with NRTL model with average RMSD value of 0.60%.

The release of certain gases to the atmosphere is controlled in many countries owing to their negative impact on the environment and human health. These gases include carbon dioxide (CO2), sulfur oxides (SOx), nitrogen oxides (NOx), hydrogen sulfide (H2S) and ammonia (NH3). Considering the major contribution of greenhouse gases to global warming and climate change, mitigation of these gases is one of the world’s primary challenges. Nevertheless, the commercial processes used to capture these gases suffer from several drawbacks, including the use of volatile solvents, generation of hazardous byproducts, and high-energy demand. Research in green chemistry has resulted in the synthesis of potentially green solvents that are non-toxic, efficient, and environmentally friendly. Deep eutectic solvents (DESs) are novel solvents that upon wise choice of their constituents can be green and tunable with high biocompatibility, high degradability, and low cost. Consequently, the capture of toxic gases by DESs is promising and environmentally friendly and has attracted much attention during the last decade. Here, we review recent results on capture of these gases using different types of DESs. The effect of different parameters, such as chemical structure, molar ratio, temperature, and pressure, on capture efficiency is discussed.

In our previous work, we showed that phosphonium-based deep eutectic solvents (DESs) are good candidates for the extractive denitrogenation of oil fuels. In particular, pyridine was successfully extracted from n-hexane and n-heptane via liquid-liquid extraction. The extraction using ‘methyltriphenylphosphonium bromide and ethylene glycol’ DES yielded high distribution ratios and selectivities of pyridine. In this work, two phosphonium-based DESs were prepared, the first one was a “binary DES” composed of methyltriphenylphosphonium bromide and glycerol and the second one was a “ternary DES” composed of methyltriphenylphosphonium bromide, glycerol, and ethylene glycol. One objective was to assess the extraction properties of the DESs for pyridine from n-alkanes. Another objective of this work was to study the influence of n-alkane chain length on the extraction performance. Thus, the oil models selected were n-hexane/pyridine, n-heptane/pyridine, and n-octane/pyridine. First, the prepared DESs were characterized for their water content, density, viscosity, and the degradation temperatures. Then the solubility of n-hexane, n-heptane, n-octane, and pyridine in the DESs was measured at 298.2 K and 1.01 bar. Afterward, the liquid-liquid equilibrium (LLE) data of the pseudo-ternary systems {n-alkane + pyridine + DES} were determined at a temperature of 298.2 K and a pressure of 1.01 bar. The consideration of a pseudo-ternary system was validated by showing that none of the DES constituents appears in the n-alkane-rich phase “the raffinate”. The solute distribution ratios and the selectivities were calculated from the experimental LLE data and compared to our previous work and some relevant literature. Furthermore, the LLE data were correlated with the non-random two-liquid (NRTL) model using ASPEN Plus. There was good agreement between the calculated experimental results. Finally, the COnductor like Screening MOdel for Real Solvents (COSMO-RS) model was used to predict the ternary tie lines for the studied systems. Based on the good distribution ratios and selectivities obtained, the studied DESs can be considered as potential solvents for extractive denitrogenation processes.

Seven new deep eutectic solvents (DESs) based on tetrabutylammonium bromide (TBAB) and tetraethylammonium p-toluene sulfonate (TEAPTS) were prepared and their viscosity determined between 298.15 and 323.15 K. The effect of temperature was modeled using an appropriate fitting procedure, proposed in this work, with a coefficient of determination R2 > 0.99 for all DES. The fitting procedure used of pre-existing experimental data in which 70 DESs were collected from the literature and refined on the basis of R2 and root mean square error (RMSE); ~10% of the data was rejected. Furthermore, about half of the refined data was fitted with a three-parameter Vogel–Fulcher–Tammann (VFT) equation with an R2 higher than 0.99. The remaining data were more adequately fitted with a two-parameter Arrhenius equation. The adjusted parameters of both models for 62 DESs were determined to estimate the viscosity. Based on R2, the VFT model was more accurate than the Arrhenius model. Moreover, additional in-lab experiments were performed for model validation at six temperatures (from 298.15 to 323.15 K). In some cases, the experimental measurements were different from those in the literature with an R2 below 0.95 indicating a large scatter in the viscosity data. Most of the highly viscous DESs considered in this study showed a rapid decay when temperature increases. Hence, the limitation of using these solvents for applications such as absorption could be overcome by operating at slightly higher temperature (i.e., 313.15 to 333.15 K).

Separation of benzene and cyclohexane remains a challenging process in petrochemical industry due to their almost similar boiling temperatures. The present work validated the performance of a reportedly benzene-selective ionic liquid (IL), i.e. 1-ethyl-3-methylimidazolium tetrafluoroborate ([C2Mim][BF4]) to extract benzene from its mixture with cyclohexane via liquid–liquid extraction. The ternary liquid–liquid equilibria of benzene+cyclohexane+[C2Mim][BF4] was investigated at 25 °C and under 1 atm with feed concentration of benzene ranging from 10 to 60 wt %. Good agreement was achieved between COSMO-RS prediction and the experimental data for the tie-lines obtained, whereby the root mean square deviation (RMSD) was 2.5%. The non-random two-liquid (NRTL) model was also successfully employed to correlate the experimental tie-lines, whereby the RMSD was 0.5%. The extractive performance of [C2Mim][BF4] was compared with other organic solvents in the literature and a few common ILs employed in our previous work. At equilibrium, IL was not present in the cyclohexane-rich layer, and the molar concentration of cyclohexane in the IL-rich layer was less than 0.01. The results indicated an efficient extraction process as the cross-contamination between the phases was minimal, and relatively less energy was required to recover the IL.

Serious environmental concerns resulting from the use of fossil fuels have urged the scientific community to concentrate their efforts on finding alternative clean fuels and sustainable raw materials. Biofuels offer a reduction in fossil fuel usage instead, potentially reducing carbon emissions. In addition, some biofuels are considered a clean and biodegradable substitute produced via different processes depending on both the raw material and the products. Ionic liquids (ILs), a new class of solvents, have many favorable characteristics, e.g., low vapor pressure, non-flammability, ability to dissolve polar and nonpolar compounds, and thermal stability. In this chapter, the use of ILs and their analogues deep eutectic solvents (DESs) in the production and treatment of biodiesel is investigated.