Room temperature ionic liquid with silver salt as efficient reaction media for propylene/propane separation: Absorption equilibrium (original) (raw)
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Reactive Ionic Liquid Media for the Separation of Propylene/Propane Gaseous Mixtures
Designed room temperature ionic liquids (RTILs) containing silver salt are presented as reactive media in separating propylene/propane gas mixtures. Solubilities of propylene and propane in the reactive media, silver tetrafluoroborate (AgBF 4 ) dissolved in 1-butyl-3-methylimidazolium tetrafluoroborate (BmimBF 4 ) and N-butyl-4-methylpyridinium tetrafluoroborate (BmpyBF 4 ), were investigated as a function of silver ion concentration, temperature, and pressure. Equilibrium data were obtained working in a temperature range between 278 and 318 K and at pressures up to 6 bar. Propylene absorption was chemically enhanced in the silver-based RTILs and was considerably higher than that in the standard RTILs. Absorption of propane in the silver-based RTILs is based on physical interactions only. A simple mathematical model based on the formation of complex species with different stoichiometry has been developed in order to describe the total propylene absorption, and the model was validated with experimental data obtained working with different concentrations of silver salt (between 0.1 and 1 M). The model parameters, equilibrium constants (K Eq,1 f(T) and K Eq,2 f(T)), and enthalpies of complexation (∆H r,1 , ∆H r,2 ) were obtained. Thermal stability of the silver ions was analyzed and to be found dependent on the silver salt concentration. Complete regeneration of the reaction media was possible at a temperature of 313 K and 20 mbar of pressure.
Separation and Purification Technology, 2017
This work presented the preparation of two new systems comprised of ionic liquids (ILs), organic solvent, and cuprous salt. Consequently, their absorption ability was investigated for propylene (C 3 H 6) and propane (C 3 H 8) and their mixtures at 100 kPa-700 kPa pressure and 298 K-318 K temperature. Representative ILs were 1-butyl-3-methylimidazolium thiocyanate ([C 4 mim]SCN) and 1-ethyl-3-methylimidazolium thiocyanate ([C 2 mim]SCN). N,N-dimethylformamide (DMF) and cuprous thiocyanate (CuSCN) were selected for the absorption system. The effects of operating parameters like Cu + concentration, pressure, temperature, and recycling of ILs absorbency were examined and compared with the literature. It was observed that C 3 H 6 shows a chemical absorption while C 3 H 8 undergoes a physical one by [C 4 mim]SCN-DMF-CuSCN and [C 2 mim]SCN-DMF-CuSCN, and an increase in concentration of Cu+ effectively improves the absorption capability for C 3 H 6 and the selectivity of C 3 H 6 /C 3 H 8. Furthermore, [C 4 mim]SCN-DMF-CuSCN had higher absorption capability and selectivity for C 3 H 6 than [C 2 mim]SCN-DMF-CuSCN. [C 4 mim]SCN-CuSCN-2.0 M absorbed 0.637 mol of C 3 H 6 per litre while 0.16 mol of C 3 H 8 per litre at 700 kPa and 298 K, with a selectivity of 3.9. This work shows that new combination of organic solvent and ILs with Cu + salt is a new class of potential reactive absorbents to separate C 3 H 6 and C 3 H 8 .
Chemical Engineering Journal, 2010
The ability of silver ions to form reversible -bond complexation with unsaturated hydrocarbons can be utilized to separate olefins from paraffins using a solution of AgNO 3 dissolved in an ionic liquid (IL). The process is suggested because of zero vapor pressure of the solvent, which results in higher purity of the separated product in comparison to when an aqueous AgNO 3 solution is applied. In the present study, 1-butyl-3-methylimidazolium nitrate ([Bmim]NO 3 ), an IL that can dissolve AgNO 3 , is applied as the solvent. The absorption of ethylene from a gaseous mixture of ethylene/ethane with constant flowrate in the silver nitrate dissolved media is investigated in silver nitrate concentrations of 1, 2 and 5 M, and temperatures within the range of 5-35 • C. The absolute absorptivity of ethylene is increased from 1.12 to 5.68 g l −1 at 25 • C when the concentration of AgNO 3 is increased from 1 to 5 M. Maximum absorption of ethylene is found at near ambient temperatures (15 • C). The absorption selectivity of ethylene to ethane increases with increase of AgNO 3 concentration and decrease with increasing temperature. The capacity of ethylene absorption in the reactive media at 25 • C and 5 M concentration of AgNO 3 is about 0.43 of that for the aqueous AgNO 3 solution. The results of an applied theoretical model for prediction of total ethylene absorption can be verified by the experimental results.
Design of a chemical absorption system for the separation of propane/propylene mixture
2014
Propane/propylene separation by distillation is the second most energy intensive distillation practiced after ethane/ethylene. Many researchers targeted finding economically attractive alternatives for this separation other than distillation. In this work, a system was designed to separate propane/propylene mixture by chemical absorption, one of the currently studied alternatives for this separation. The reaction medium consists of an ionic liquid namely 1-butyl-3-methylimidazolium tetrafluoroborate (BMImBF4) with dissolved silver tetrafluoroborate salt. The proposed system is mainly composed of a packed bed absorber along with a vertical flash separator. In addition, a heat exchanger, trim cooler, trim heater and a throttling valve are included in the system. Taking in consideration the mass transfer regimes, successful simulation of the process supports the possibility that the suggested system can be a potential alternative for propane/propylene conventional separation.
Gaseous Hydrocarbon Separations Using Functionalized Ionic Liquids
Oil & Gas Science and Technology – Revue d’IFP Energies nouvelles, 2016
The functionalization of the side chains on the cation or the anion of an ionic liquid is a common approach to tailor its properties for different processes including the separation of gases. In this paper, we present the current state of the art concerning the usage of ionic liquids for hydrocarbon separations. We also show how the functionalization of ionic liquids or the appropriate anion/cation combinations can contribute to the increase of the performance of the ionic liquids for the separation of gaseous hydrocarbonseither by improving the capacity of the ionic liquid to absorb a given gas or by increasing the selectivity towards a particular hydrocarbon. Original results concerning the usage of olefin-complexing metal salts of lithium (I), nickel (II) and copper (II) dissolved in ionic liquids for selectively absorbing light olefins are presented. It is observed that the absorption capacity of an imidazolium-based ionic liquid is doubled by the addition of a copper (II) salt. This result is compared with the effect of the functionalization of the ionic liquid and the advantages and difficulties of the two approaches are analyzed.
Chemistry of Materials, 2006
The ionic liquids 1-butyl-3-methyl imidazolium BMIM + NO 3and BMIM + BF 4have been successfully utilized to increase the activity in reversible π-complexation with olefins of silver cations in silver polymer electrolytes consisting of AgNO 3 dissolved in poly(2-ethyl-2-oxazoline) (POZ). In the absence of the ionic liquids, AgNO 3 is not readily dissolved in POZ and is instead because of its high lattice energy present mostly as chemically less active ion pairs or higher order aggregates. The activation of Ag + in silver polymer electrolytes in the presence of these ionic liquids is principally due to the reduction of the interactions between Ag + and NO 3produced by the interaction between BMIM + and NO 3-, and this effect does not occur in the presence of common salts such as NaNO 3. We investigated these systems with FT-IR, FT-Raman, and XPS and calculated the theoretical electronic structures of the relevant species. The increased activity in these membranes of Ag + in reversible π-complexation with olefins was further confirmed by evaluating the sorption and desorption behavior of propylene and the performances of the membranes in the separation of olefin/paraffin mixtures.
Journal of Membrane Science and Research, 2015
Article history: Traditional systems for olefin/paraffin separation, like low-temperature distillation, are expensive and very energy consuming, and therefore, alternative separation methods are desired. Facilitated transport membranes are new tools for this separation to be substituted in large scale separation of olefin-paraffin mixtures. To design a membrane process for olefin-paraffin separation, equilibrium data is required. In the present work, silver nitrate (AgNO3) was used as the carrier for facilitated transport of propylene. The equilibrium constant value of the reaction between propylene and silver ions was determined by the volumetric method. The influence of pressure, temperature and silver ion concentration on equilibrium constant value was evaluated.
Talanta, 2009
The extraction/enrichment of omega-3 polyunsaturated fatty acid methyl esters (PUFAMEs) by hydrophobic ionic liquids (ILs) containing silver salts as the extraction phase has been extended to include equilibrium studies. The extraction time, organic solvents, IL structures, and AgBF4 concentrations all influence the organic/ionic liquid biphasic extraction equilibrium. Each of these parameters was studied. The PUFAME distribution ratios, partition coefficients and the PUFAME-Ag+ complex stability constants were determined from gas chromatography (GC) analyses. When AgBF4 dissolved in [hmim][PF6] was used as the extraction phase, both the distribution ratios of PUFAMEs and the stability constants of PUFAME-Ag+ complexes increased significantly with an increase in the degree of unsaturation of the PUFAMEs. Investigation of the IL structures indicated that larger PUFAME distribution ratios were obtained when AgBF4 was dissolved in hydrophobic ILs than in hydrophilic ILs. Higher PUFAME distribution ratios occurred using shorter chain alkanes as the organic solvents. The extraction isotherms for PUFAME uptake were obtained from which saturated extraction capacities were determined. Compared with previous aqueous AgNO3 extractions, a more efficient extraction of PUFAMEs was obtained by using a hydrophobic IL containing AgBF4. Much higher extraction capacities and significant shorter operation times were also achieved.
Separation Science and Technology, 2014
Separation of aromatic solvents, from mixtures containing aliphatic solvents as the major fraction, is important, inter alia, for its reuse in industrial processes. This report deals with the use of a designed and synthesised ionic liquid (N-butyl-N-methyl-2-oxopyrrolidonium bromide), for the separation of benzene, toluene, ethylbenzene and xylene (BTEX), including all the isomers of xylene. For comparison purposes, a previously-used ionic liquid (1-ethyl-3methylimidazolium ethyl sulphate) was also synthesised and used. The experimental parameters established for the separation / extraction of the mixed standard of BTEX were applied to the separation / extraction of the components of BTEX from the reformate fraction of an oil refining process. The method was tested for BTEX components varying in concentration from 0.5 to 10 %. The results show that the new ionic liquid gives higher extraction efficiency than the one used in a previous project. The results are as good as that obtained by a local oil refinery which used a conventional solvent. Furthermore, the results reveal a general increase in percentages Downloaded by [UNIVERSITY OF KWAZULU-NATAL] at 05:54 19 June 2014 ACCEPTED MANUSCRIPT ACCEPTED MANUSCRIPT 2 extracted in the following order: m-xylene < p-xylene ~ o-xylene < ethyl benzene < toluene < benzene.