This work studies the solubility of CO2 in phosphonium-based ionic liquids which, unlike imidazolium-based ILs, have received little attention despite their interesting properties. Phosphonium-based ionic liquids have attractive properties such as negligible vapor pressure, high thermal stability, large liquidus range and non-flammability, high solubility, compatibility with strongly alkaline solutes, stabilizing effect on palladium catalysts, effective media for Heck and Suzuki reactions and their low cost. The present invention provides new data of the alternative solvent for CO2 removal process which is phosphonium-based ionic liquid.
The Henry's constant of C02 in this phosphonium-based ionic liquid was also determined and a plot of the Henry's constant versus inverse temperature is presented. Their study stated that the gas solubility of phosphonium-based ionic liquids is of the same magnitude as the gas solubility of the more popular imidazolium-based ionic liquids. The Henry's law constants in both imidazolium- and phosphonium-based ionic liquids are similar for carbon dioxide (C02) solubility.
Phosphonium-based ionic liquids are more thermally stable than imidazolium-based ionic liquids and cheaper to manufacture [17]. To my knowledge, no work has been reported on the solubility of CO2 in 1,10-bis(trioctylphosphonium-1-yl)decane-dioctylsulfosuccinate-phosphonium-based ionic liquid.
Intensive energy required during the regeneration step to break the chemical bonds between the absorbed C02 and solvent. Energy is also required to generate steam
Removal of C02 is often required to improve the fuel quality (calorific value) of the natural gas. As a consequence, removal of C02 to acceptable specifications is required prior to transportation of natural gas or by pipeline. In the natural gas processing industry, various technologies have been used for C02 removal, including chemicals.
Commercial amine solutions that can be used for this purpose include monoethanolamine (MEA), N-methyldiethanolamine (MDEA), and diethanolamine (DEA). Intensive energy is required during the regeneration step to break the chemical bonds between the absorbed CO 2 and the solvent.
Corrosivity of the amine. Amines can rapidly corrode low alloy steel such as
C02 loading capacity is limited by concentration (or dilutes) ofthe amine solution
IONIC LIQUID
Room temperature ionic liquids (RTILs) possess a unique set of physicochemical properties that make them suitable in numerous task-specific applications in which conventional solvents are inapplicable or insufficiently effective. Several studies have shown that, although not 100% inert, some ionic liquids that include 1,3-dialkyl imidazolium cations are generally more resistant than traditional solvents under certain harsh process conditions, such as those occurring in oxidation processes, photolysis and radiation [19] . A number of precautions for the synthesis of colorless ionic liquids have been described, and a procedure for decolorizing impure ionic liquids using acidic alumina and activated carbon has also been proposed [19].
The degree of polarity can be varied by adjusting the length of the 1-alkyl chain (in 1,3-substituted imidazolium cations) and the counterion. Although little variation in properties can be expected between salts of the same cation of these species, the actual differences can be dramatic: for example, [bmim]PF6" is not miscible with water, whereas the recent interest in ILs with regard to green chemistry and The associated development of new solvents and alternative technologies has been largely a result of their negligible vapor pressure, which inhibits evaporation to the air and enables simple reuse and recycling.
The missing vapor pressure has very significant advantages over other volatile organic chemicals (VOCs). Therefore, ionic liquids are non-flammable and non-explosive, so long-range distribution through air cannot be expected [19].
C02 SOLUBILITY IN PHOSPHONIUM-BASED IONIC LIQUIDS
- Solubility Measurement Experimental Setup
Phosphonium-based ionic liquids are thermally more stable than imidazolium-based ionic liquids [22]. The TGA data reported are often not fully indicative as they only show a dynamic property of the ionic liquid. The phosphonium-based ionic liquids were then analyzed by GC-MS and found to be stable with no decomposition products such as hexane and tetradecyl(dihexyl)phosphine.
On the other hand, heating the imidazolium-based ionic liquid l-butyl-3-methylimidazolium chloride at 250°C for 1 week resulted in its decomposition as determined by GC-MS analysis [24]. Solubility is measured in terms of moles of C02 gas absorbed in the ionic liquid to the moles of ionic liquid used in this experiment. The system is designed so that measurement of C02 solubility can be repeated several times with the same ionic liquid sample.
The o-ring will be used between the lid and the pressure cell itself to prevent any leakage from occurring. For the ionic liquid without CO2, the sample is dried in a vacuum oven and placed directly into the Shimadzu model IR spectrometer.
For the ionic liquid contacted with C02, it is collected after the solubility
Procedure of Experimental Setup Leakage Test
Vacuum is applied to the whole system to ensure no other gases in the system
The pressure reading showed bypressure gauge is monitored for 5-8 hours
Vb is opened to let the C02 gas exposed to the whole system. Vc is maintain
The pressure reading showed bypressure gauge is monitored for 24 hours
Ionic liquid is dried in the vacuum oven at 80°C for 24 hours. 2.00 g of the ionic liquid was added directly from the oven to the pressure cell and immediately the pressure cell was closed and attached to the unit. After equilibrium, as indicated by a negligible change in pressure, the pressure is measured again to determine the amount of CO2 gas remaining in the vapor phase.
After equilibrium as indicated by negligible pressure change, the pressure is measured again to determine the amount of C02 gas left in vapor phase. The
Determination of initial volume, \um (backward method)
It can be seen that the solubility in terms of mole fraction and molality of CO2 in the ionic liquid [PgggCioPgsa] docusate increases with increasing pressure. Based on the graphs obtained, it was found that the mole fraction and molality of CO2 gas in the ionic liquid is higher at high pressure compared to low pressure. The number of gas molecules is reduced, while the number of CO2 gas molecules dissolved in the solution is increased.
Based on the comparison with the literature data of other ionic liquids, it showed that the mole fraction for [bmim][PF6] is smaller than the mole fraction of this ionic liquid at the temperature of 298.15 K. This indicated that this ionic can absorb more C02 compared to [bmim]]PF6] which is more than 50% of C02 gas. From Table 4.2, it can be seen that the Henry's law constant of the systems studied increases with increasing temperature, indicating that the solubility of C02 decreases with increasing.
Zhang et al showed that the Henry's law constant of [P6j 6.6, i43[Ci2H25PhS03] increases with increasing temperature, indicating that the solubility of C02 decreases with increasing temperature. Based on the above comparison, it showed that the logarithms of Henry's Law Constant for [PsssQoPsss] docusate are following the same trend as. The solubility results of the newly synthesized ionic liquid [PggsCioPgss] docusate are very important in many industrial applications.
Since most industrial processes operate at high pressures up to 100 bar (10 Mpa), the solubility measurement can be performed at higher pressures up to 10 to 15 Mpa. Yokozeki, Phase behavior of carbon dioxide in ionic liquids: [emim][acetate], [emim][trifluoroacetate], and [emim][acetate] + [emim][trifluoroacetate] mixtures, J. Hoffmann, Surprisingly high solubility of the ionic liquid trihexyltetradecylphosphonium chloride in dense carbon dioxide, Green Chem.
Scovazzo, Gas permeabilities, solubilities, diffusivities, and diffusivity correlations for ammonium-based ionic liquids at room temperature compared to RTIL data for imidazolium and phosphonium, Chem. Brennecke, Solubility and thermodynamic properties of gases in the ionic liquid l-n-butyl-3-methylimidazolium gas properties in the ionic liquid l-n-butyl-3-methylimidazolium hexafluorophosphate, J. Scovazzo, Solubility, diffusivity and permeability of gases in a phosphonium-based ionic liquid at room temperature : data and correlations, in phosphonium-based room temperature ionic liquids: data and correlations,.
Hoffmann, The surprisingly high solubility of the ionic liquid trihexyltetradecylphosphonium chloride in dense Solubility of the ionic liquid trihexyltetradecylphosphonium chloride in dense carbon dioxide, Green Chem. Characterization of phosphonium ionic liquids via linear solvation energy relationship and their use as GLC ionic liquids via linear solvation energy relationship and their use as GLC.
Understanding on ionic liquids properties and solubility of C02 in ionic liquids 4. Study on chemical properties of phosphonium-based ionic liquids
Understanding on how C02 solubility differs in phosphonium-based ionic liquids and imidazolium-based ionicliquid
Research and study on method of C02 solubility measurement 7. Study the factors that govern the solubility of C02 in ionic liquids
Consultation process about the equipment design with supervisor and fabricator
Finalized all the equipments needed to set up the experiment 13. Set up the experimental apparatus for solubility measurement
Solubility measurement of C02 in [PsssQoPm] docusate
GANTT CHART AND KEY MILESTONE
![Table 2.1: Characteristic of Modern Ionic Liquid [20]](https://thumb-ap.123doks.com/thumbv2/azpdforg/10256767.0/16.829.76.743.147.535/table-2-characteristic-of-modern-ionic-liquid-20.webp)
