We have developed a ternary equation of state (EOS) model for the CO2/H2S/1-butyl-3-methylimidazolium methylsulfate ([bmim][MeSO4]) system to understand separation of these gases using room-temperature ionic liquids (RTILs). The present model is based on a modified RK (Redlich−Kwong) EOS, with empirical interaction parameters for each binary system. The interaction parameters have been determined using our measured VLE (vapor−liquid equilibrium) data for H2S/[bmim][MeSO4] and literature data for CO2/[bmim][MeSO4] and CO2/H2S. Due to limited VLE data for H2S/[bmim][MeSO4], we have also used VLLE (vapor−liquid−liquid equilibrium) measurements to construct the EOS model. The VLLE for H2S/[bmim][MeSO4] is highly asymmetric with a narrow (mole fraction H2S between 0.97 and 0.99) LLE gap which is the first such case reported in the literature and exhibits Type V phase behavior, according to the classification of van Konynenburg and Scott. The validity of the ternary EOS model has been checked by conducting VLE experiments for the CO2/H2S/[bmim][MeSO4] system. With this EOS model, solubility (VLE) behavior has been calculated for various (T, P, and feed compositions) conditions. For large (9/1) and intermediate (1/1) CO2/H2S feed ratios, the CO2/H2S gas selectivity is high (10 to 13, compared with <4.5 in the absence of ionic liquid) and nearly independent of the amount of ionic liquid added. For small CO2/H2S mole ratios (1/9) at 298.15 K, increasing the ionic liquid concentration increases the CO2/H2S gas selectivity from about 7.4 to 12.4. For high temperature (313.15 K) and large CO2/H2S feed ratios, the addition of the ionic liquid provides the only means of separation because no VLE exists for the CO2/H2S binary system without the ionic liquid.
"Industrially important alkanolamines for this process are di-isopropanolamine (DIPA), diethanolamine (DEA), mono-ethanolamine (MEA), and N-methyl-diethanolamine (MDEA). However due to drawbacks in the industrial application of aqueous solutions of alkanolamines, consisting alkanolamines degradation to create corrosive byproducts and transfer of water into the gas stream during the desorption stage and loss of alkanolamine , that make the aforementioned process expensive       , there is a growing attention in looking into the pros of changing aqueous alkanolamines with other alternative solvents, such as ionic liquids (ILs) . "
[Show abstract][Hide abstract] ABSTRACT: Prediction of acid gases solubilities in ionic liquids (ILs), have recently emerged as promising mediums for refining of natural gas, using powerful paradigms is of great importance from technical and economical point of view. In this respect, this study aims at appraising the effectiveness of one of the new generation soft computing methodologies called gene-expression programming (GEP) for estimating the hydrogen sulfide (H2S) solubility in ionic liquids (ILs). A total data set of 465 experimental data belonging to 11 ionic liquids, which gathered from literatures, were used to develop a general correlation. The temperature and pressure accompanied with acentric factors and critical temperature and pressure of ILs were used as independent input variables, while H2S solubility as dependent output variables. The modeling results showed the coefficient of determination (R-2) of 0.9902 and 0.0438% mean absolute relative error (MARE) for the predicted solubilities from the corresponding experimental values. Therefore, the model is comprehensive and accurate enough to be used to predict the H2S solubility in various ILs. In addition, the GEP-model predictions were compared with the outputs of two well-known engineering approaches named Soave-Redlich-Kwong (SRK) and Peng-Robinson (PR). Results showed that the proposed evolutionary-based method was more accurate than the widely used aforementioned thermodynamic models.
Journal of Supercritical Fluids The 08/2014; 92. DOI:10.1016/j.supflu.2014.05.003 · 2.37 Impact Factor
"CO 2 and H 2 S, from natural gas is of great importance for operational, economical, and environmental as well as health and well-being reasons. Among various treatment methods have been reported for the removal of impurities (acid gases) and purify natural gases, the gas-liquid absorption in amine based solvents, is one of the most commonly used processes for the removal of acid components in industrial natural gas treatment and sweetening plants          . "
[Show abstract][Hide abstract] ABSTRACT: For the design and development of new processes of gas sweetening using ionic liquids (ILs), as promising candidates for amine solutions, an amazing model to predict the solubility of acid gases is of great importance. In this direction, in the current study, the capability of artificial neural networks (ANNs) trained with back-propagation (BP) and particle swarm optimization (PSO), to correlate the solubility of H2S in 11 different ILs have been investigated. Different structures of three-layer feed forward neural network using acentric factor (ω), critical temperature (Tc), critical pressure (Pc) of ILs accompanied by pressure (P) and temperature (T), as input parameters, were examined and an optimized architecture has been proposed as 5–9–1.Implementation of these models for 465 experimental data points collected from the literature shows coefficient of determination (R2) of 0.99218 and mean squared error (MSE) of 0.00025 from experimental values for PSO-ANN predicted solubilities while the values of R2= 0.95151and MSE = 0.00335 were obtained for BP-ANN model. Therefore, through PSO training algorithm we are able to attain significantly better results than with BP training procedure based on the statistical criteria.
Journal of Supercritical Fluids The 08/2014; 95:525-534. DOI:10.1016/j.supflu.2014.08.011 · 2.37 Impact Factor
"Although it may be tempting to generalize, not all mixtures of gases with ILs will behave in this fashion. For example, Shiflett and Yokozeki  suggested type V phase behavior for the system H 2 S + [bmim][PF 6 ] based on their observation of a lower "
[Show abstract][Hide abstract] ABSTRACT: As part of an IUPAC task force, this study was initiated in collaboration with a number of different laboratories throughout the world to help understand the reasons for the discrepancies observed in ionic liquid properties published in literature and to establish an acceptable data bank for the investigated properties of one representative ionic liquid. This study presents experimental high-pressure solubility data of carbon dioxide in the ionic liquid 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide within the temperature range of 280–370K and pressures up to 14MPa. The data are compared with those obtained in other laboratories and the differences are not alarming. In addition, a discussion is presented on the carbon dioxide+ionic liquid phase behavior according to the classifications of Scott and van Konynenburg. Such an understanding can greatly help to predict what kinds of phase phenomena may be expected of such systems in regions outside those measured experimentally and can be a very valuable map when designing and optimizing processes involving gases and ionic liquids.
Journal of Supercritical Fluids The 12/2010; 55(2):825-832. DOI:10.1016/j.supflu.2010.09.042 · 2.37 Impact Factor
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