Trifluorophosphate Ionic Liquid Research Articles

Influence of ionic liquid on polar organic compounds solubility in dense CO2 phase

Accurate measurement and prediction of the phase behaviour of mixtures involved in a chemical process are crucial for its optimisation. Given the importance of CO2 conversion technologies and considering possible benefits of CO2-ionic liquid biphasic systems, i.e., facilitating a product separation, we investigated the high-pressure behaviour of components of interest in a recently developed process of cyclic carbonate synthesis directly from CO2 and potentially bio-based alcohols. The solubility of 1,2-butanediol and 1,2-butylene carbonate in a dense carbon dioxide phase was determined experimentally at the temperature of 313.2 K and pressures between 6 and 18 MPa. The influence of 1-hexyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate ionic liquid, [hmim][FAP], as a solvent, on the solubility of these compounds in CO2-rich phase, in ternary (CO2 + 1,2-butanediol + [hmim][FAP]), CO2 + butylene carbonate + [hmim][FAP]) and quaternary (CO2 + 1,2-butanediol + butylene carbonate + [hmim][FAP]) mixtures was investigated. The experimental results of the two binary systems were correlated using the density-based Chrastil equation. The knowledge of phase equilibria behaviours reported in this work will be useful for designing chemical conversions of carbon dioxide using [hmim][FAP] ionic liquid as reaction solvents.

High Performance Graphene-Based Electrochemical Double Layer Capacitors Using 1-Butyl-1-methylpyrrolidinium tris (pentafluoroethyl) trifluorophosphate Ionic Liquid as an Electrolyte

There are several advantages to developing electrochemical double-layer capacitors (EDLC) or supercapacitors with high specific energy densities, for example, these can be used in applications related to quality power generation, voltage stabilization, and frequency regulation. In this regard, ionic liquids capable of providing a higher voltage window of operations compared to an aqueous and/or polymer electrolyte can significantly enhance the specific energy densities of EDLCs. Here we demonstrate that EDLCs fabricated using ionic liquid 1-butyl-1-methylpyrrolidinium tris (pentafluoroethyl) trifluorophosphate (BMP-FAP) as an electrolyte and few layer liquid-phase exfoliated graphene as electrodes show remarkable performance compared to EDLC devices fabricated with aqueous potassium hydroxide (6M) as well as widely used ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate (BMIM-PF6). We found that graphene EDLC’s with BMP-FAP as an electrolyte possess a high specific energy density of ≈25 Wh/kg along with specific capacitance values as high as 200 F/g and having an operating voltage windows of >5 volts with a rapid charge transfer response. These findings strongly indicate the suitability of BMP-FAP as a good choice of electrolyte for high energy density EDLC devices.

Syntheses and Properties of Methoxy and Nitrile Functionalized Imidazolium Tris(pentafluoroethyl)trifluorophosphate Ionic Liquids

An alternative and more benign method was employed to synthesize tris(pentafluoroethyl)trifluorophosphate (FAP) ionic liquids (ILs). Ion exchange chromatography was used instead of the typical electrochemical fluorination developed by Ignat’ev and co-workers. The resulting procedure is simple and can be readily performed, as the use of corrosive hydrofluoric acid and the production of toxic and explosive byproducts were circumvented. Functionalization of the alkyl group of the imidazolium cation with a methoxy and a nitrile moiety was employed to observe changes in properties. The success of the synthesis was confirmed by 1H, 19F, and 31P NMR, IR, and UV–vis spectroscopy techniques. Quantitative product yields of approximately 80% (w/w) were obtained. The water content and viscosity values of the synthesized FAP-based ILs were found to be lower compared to other fluorine-containing ionic liquids. Thermal analyses resulted in high thermal degradation temperatures greater than 573.15 K. Electrochemical anal...

Influence of Water on the Carbon Dioxide Solubility in [OTf]- and [eFAP]-Based Ionic Liquids

The solubility of high-pressure carbon dioxide in mixtures of ionic liquid and water was determined experimentally for 1-ethyl-3-methylimidazolium trifluoromethanesulfonate and 1-alkyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate ionic liquids (where alkyl is ethyl, butyl, or hexyl). Experiments were performed at 313.15 K and/or 318.15 K, at pressures up to 10 MPa, and for various compositions (dry ionic liquids, 0.1 or 10 wt % of water), depending on the ionic liquid under investigation. It was found that the solubility of carbon dioxide in tris(pentafluoroethyl)trifluorophosphate-based ionic liquids is not affected by the water content, whereas for 1-ethyl-3-methylimidazolium trifluoromethanesulfonate, the carbon dioxide sorption capacity is reduced by up to 10%, when 10 wt % of water is present in the system, at the same temperature and pressure.

MD study of structure and dynamic properties of the 1-n-alkyl-3-methylimidazolium tris(perfluoroalkyl)trifluorophosphate ionic liquids

In this study, we applied classical molecular dynamics (MD) simulations to understand the structure, dynamics and transport properties of the room-temperature 1-alkyl-3-methylimidazolium family with tris(perfluoroalkyl)trifluorophosphate ionic liquids, abbreviated as [Cnmim][eFAP]. Calculated densities of ionic liquids agree well with experimental data. Local structures were characterized by studying the center-of-mass (COM) and partial site-site RDFs, combined distribution functions (CDFs) and dihedral angles distribution of n-alkyl side chains in the imidazolium cations. The hydrogen bonding between Fluor atoms of anions and hydrogen atoms of imidazolium ring of cations were studied by contour maps of CDFs. Also, dynamical properties of these ILs such as mean-square displacement (MSDs) for center-of-mass of ions, ionic diffusion coefficients and the cationic transference numbers are calculated by simulation in the NVT ensemble. Results show that the length of alkyl-side chain of cation is the major factor to affect these properties.

High Pressure Rheological Behavior of 1-Ethyl-3-methylimidazolium n-Hexylsulfate and Trihexyl(tetradecyl)phosphonium Tris(pentafluoroethyl)trifluorophosphate

Ionic liquids have been broadly studied in the past decade for being used as lubricants or lubricant additives. The rheological characterization of these fluids is very important in this context because it determines to a great extent their performance for different lubricants applications, such as hydraulic or gear lubricants. Thus, in this work we have performed the rheometric characterization of two ionic liquids (ILs), 1-ethyl-3-methylimidazolium n-hexylsulfate and trihexyl(tetradecyl)phosphonium tris(pentafluoroethyl)trifluorophosphate, in the temperature range from 298.15 to 353.15 K up to 75 MPa and shear rates up to 1000 s–1. For this aim, the setup of a new device for rheological characterization at high pressure based on Couette flow and concentric cylinders was undertaken in this work. Moreover the pressure–viscosity and temperature–viscosity coefficients of these ILs have been calculated. Both ILs present Newtonian behavior in the studied conditions. The trifluorophosphate IL has strong pressu...

Tribological Behaviour of PVD Coatings Lubricated with a FAP− Anion-Based Ionic Liquid Used as an Additive

This paper studies 1-butyl-1-methylpyrrolidinium tris(pentafluoroethyl) trifluorophosphate ionic liquid ([BMP][FAP]) as a 1 wt% additive to a polyalphaolefin (PAO 6) in the lubrication of CrN and TiN PVD coatings. Friction and wear behaviour were determined by using a ball-on-plate reciprocating tribometer at two loads (20 and 40 N) and a reciprocating frequency of 10 Hz. The tribological behaviour of this mixture has also been compared to a traditional oil additive, like zinc dialkyldithiophosphate (ZDDP). As an additive, ionic liquid exhibited an important friction and wear reduction compared to the base oil. However, tests conducted with ZDDP show slightly better results. XPS was used to analyse wear surfaces. The interactions of each additive with the surface contributed to improving the tribological behaviour of the lubricants.

Friction and anti-wear properties of two tris(pentafluoroethyl)trifluorophosphate ionic liquids as neat lubricants

The tribological behaviour was evaluated for two ionic liquids (ILs) as neat lubricants for the sliding pair stainless steel AISI420 and 100Cr6 under four loads (14, 18, 22 and 26N). The ILs contain the same anion, tris(pentafluoroethyl)trifluorophosphate [(C2F5)3PF3]− (also known as [FAP]−), combined with the cations 1-butyl-2,3-dimethylimidazolium [C4C1C1Im]+ or trihexyl(tetradecyl)phosphonium [P6,6,6,14]+. The IL [P6,6,6,14][(C2F5)3PF3] showed always better lubricating properties than [C4C1C1Im][(C2F5)3PF3] in terms of friction coefficient and wear volume. Under the same conditions, tribological tests were performed with two perfluoropolyethers as reference lubricants developing, in general, higher friction coefficients and also higher wear volumes than those obtained with both ILs. Surface interactions were studied by SEM observations and XPS analyses of the neat ILs and of the wear tracks.

Absorption of Carbon Dioxide, Nitrous Oxide, Ethane and Nitrogen by 1-Alkyl-3-methylimidazolium (Cnmim, n = 2,4,6) Tris(pentafluoroethyl)trifluorophosphate Ionic Liquids (eFAP)

We measured the densities of 1-alkyl-3-methylimidazolium (C(n)mim, n = 2,4,6) tris(pentafluoroethyl)trifluorophosphate ionic liquids (eFAP) as a function of temperature and pressure and their viscosities as a function of temperature. These ionic liquids are less viscous than those based in the same cations but with other anions such as bis(trifluoromethylsulfonyl)imide. The ionic liquids studied are only partially miscible with water, their solubility increasing with the size of the alkyl side-chain of the cation and with temperature (from x(H(2)O) = 0.20 ± 0.03 for [C(4)mim][eFAP] at 303.10 K to x(H(2)O) = 0.49 ± 0.07 for [C(6)mim][eFAP] at 315.10 K). The solubility of carbon dioxide, nitrous oxide, ethane, and nitrogen in the three ionic liquids was measured as a function of temperature and at pressures close to atmospheric. Carbon dioxide and nitrous oxide are the more soluble gases with mole fraction solubilities of the order of 3 × 10(-2) at 303 K. The solubility of these gases does not increase linearly with the size of the alkyl-side chain of the cation. The solubilities of ethane and nitrogen are much lower than those of carbon dioxide and nitrous oxide (mole fractions 60% and 90% lower, respectively). The higher solubility of CO(2) and N(2)O can be explained by more favorable interactions between the solutes and the polar region of the ionic liquids as shown by the enthalpies of solvation determined experimentally and by the calculation of the site-site solute-solvent radial distribution functions using molecular simulation.

A new 1-hexyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate ionic liquid based ultrasound-assisted emulsification microextraction for the determination of organic ultraviolet filters in environmental water samples

A novel microextraction approach termed ionic liquid based ultrasound-assisted emulsification microextraction (IL-USAEME) combined with high-performance liquid chromatography-ultraviolet (HPLC-UV) was developed for the preconcentration and detection of organic ultraviolet (UV) filters in environmental water samples. An ionic liquid (IL) was used in place of an organic solvent as in conventional USAEME. In the study, orthogonal array designs (OAD) were employed for the optimization of the extraction parameters: type of IL, pH of the sample, extraction volume, ultrasonic time and salt concentration. In the first step, a mixed level OAD matrix, OA16 (41×212) was employed for the initial optimization. Based on the results of the first step, an ultra-hydrophobic IL, 1-hexyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate was chosen as the IL extractant and sample pH was set at a value of 3. Ultrasonic time, extraction volume and salt concentration were further optimized in the second step by an OA16 (45) matrix. Under the latter optimized conditions, calibration curves with coefficients of estimation higher than 0.997 over the concentration range of 5 and 1000ng/ml, and the relative standard deviations for six replicates of the extraction from 2.6 to 6.6% were obtained. The limits of detection for four organic UV filters were between 0.5 and 1ng/ml. The validated technique was applied to the analysis of organic UV filters in environmental water samples.

Absorption of CO2 in aqueous mixtures of N-methyldiethanolamine and guanidinium tris(pentafluoroethyl)trifluorophosphate ionic liquid at high-pressure

In this paper, the solubility of CO2 in aqueous blends of N-methyldiethanolamine (MDEA) and guanidium tris(pentafluoroethyl)trifluorophosphate [gua]+[FAP]− ionic liquid was measured at 313.15, 333.15 and 353.15K and at partial pressures up to 3MPa. Reported data were loading capacity (mol CO2/total mol) as a function of CO2 partial pressure at equivalent temperature. A simple correlation was used to predict the solubility of CO2 in the mixtures. The predicted data showed good agreement with the experimental data. In this study, it has been found that adding [gua]+[FAP]− into the aqueous MDEA has lowered the absorption capacity and this effect was significant at higher concentrations.

Recovery of n-butanol using ionic liquid-based pervaporation membranes

Biobutanol (n-butanol) offers the possibility of expanding the production of bulk chemicals and fuels based on renewable resources. A drawback in the microbial production of n-butanol is the energy-intensive product recovery process, making biobutanol expensive. One method for overcoming this limitation is the application of supported ionic liquid membranes (SILMs) for continuous product removal.In this work, the pervaporation performance of SILMs with tetracyanoborate and tris(pentafluoroethyl)trifluorophosphate ionic liquids (ILs) was investigated. Pervaporation was carried out at 37°C using binary mixtures of n-butanol and water with n-butanol concentrations lower than 5wt.%. Two concepts for immobilisation of ILs were tested using nylon or polypropylene as support material. ILs were immobilised by inclusion between silicone layers or by dissolution in poly(ether block amide). It was observed that a higher affinity of the IL for n-butanol increases the permeability of the membrane for more than three times, whereas no changes in the selectivity occurred. Furthermore it was shown, that fluxes increased with an increasing IL content in the membrane. The maximum permeate flux achieved was 560g/(m2h), and the highest concentrations of n-butanol in the permeate was found to be 55wt.%. In future thickness of SILMs needs to be reduced to make these membranes competitive with respect to conventional pervaporation membranes.

Measurements of pVT, viscosity, and surface tension of trihexyltetradecylphosphonium tris(pentafluoroethyl)trifluorophosphate ionic liquid and modelling with equations of state

In spite of the great importance of the volumetric, transport, and surface properties of phosphonium-based ionic liquids, only limited information on these values seems to be available in the open literature. In this work, we present the results for the density measurements of the trihexyltetradecylphosphonium tris(pentafluoroethyl)trifluorophosphate, [(C 6) 3PC 14][(C 2F 5) 3PF 3, FAP] over the ranges of temperature and pressure, T = (293.15 to 343.15) K and p = (0.1 to 25.0) MPa, respectively with an estimated uncertainty of ±0.5 kg · m −3. The viscosity and the surface tension were measured over the ranges T = (283.10 to 363.17) K and T = (298.51 to 343.29) K with maximum uncertainties of ±2.0% and ±0.4 mN · m −1. The experimental results on density were correlated using the Goharshadi–Morsali–Abbaspour equation of state. From this equation, thermomechanical coefficients as the isothermal compressibility, thermal expansivity, thermal pressure, and internal pressure were calculated. The Sanchez–Lacombe equation of state was also used for ( pVT) correlation and the estimation of the free volume of [(C 6) 3PC 14][FAP] which has been compared with other [(C 6) 3PC 14]-based ionic liquids with variable anions. The Vogel–Fulcher–Tammann (VFT) equation for viscosity was used to correlate the viscosity. From the analysis of viscosity results for [(C 6) 3PC 14]-based ionic liquids, a new prediction method has been developed for this property. Using the linear variation of the surface tension with the temperature, the surface entropy and enthalpy of [(C 6) 3PC 14][FAP] were found. The reciprocal of dynamic viscosity (or fluidity) was correlated with temperature and a new relation between fluidity and surface tension was tested to [(C 6) 3PC 14] ionic liquids.

Use of ethyl-dimethyl-2-methoxyethylammonium tris(pentafluoroethyl)trifluorophosphate as base oil additive in the lubrication of TiN PVD coating

This paper discusses and compares the use of ethyl-dimethyl-2-methoxyethylammonium tris(pentafluoroethyl)trifluorophosphate ionic liquid [(NEMM)MOE][FAP] and the traditional zinc dialkyldithiophosphate (ZDDP) as 1wt% additives to a polyalphaolefin (PAO 6) in the lubrication of TiN PVD coating. Tribological tests performed using a ball-on-plate reciprocating tribometer showed how both additives improve the anti-friction and anti-wear behaviors of the base oil for the two loads tested. However, the traditional additive ZDDP showed the lowest friction coefficient in all cases. Interferometry and XPS analyses showed that the formation of tribofilms resulting from the interaction of the ionic liquid with the surface contributed to the tribological improvement.

Role of Carbon Porosity and Ion Size in the Development of Ionic Liquid Based Supercapacitors

The role played by carbon porosity and electrolyte chemistry in the development of double-layer supercapacitors based on solvent-free ionic liquids (ILs) of a wide electrochemical stability window is investigated. Voltammetric studies performed in -methyl--butyl-pyrrolidinium bis(trifluoromethanesulfonyl)imide , -trimethyl--propylammonium bis(trifluoromethanesulfonyl)imide, and -methyl--butyl-pyrrolidinium tris(pentafluoroethyl)trifluorophosphate ionic liquids and —tetraethyl ammonium bis(trifluoromethanesulfonyl)imide solutions demonstrate that the pore-to-ion size ratio and the porous electrode/IL interface properties may have a higher impact on the electrode electrical response than do the inherent IL bulk properties. The effect of carbon porosity on the electrode capacitance and charge storage capability in both the positive and negative potential domains is discussed in relation to the IL properties, and an estimation of the upper limits of the performance of IL based supercapacitors with carbons of optimized porosity is reported.

Lubrication of CrN Coating With Ethyl-Dimethyl-2-Methoxyethylammonium Tris(pentafluoroethyl)Trifluorophosphate Ionic Liquid as Additive to PAO 6

This paper studies ethyl-dimethyl-2-methoxyethylammonium tris(pentafluoroethyl)trifluorophosphate ionic liquid [(NEMM)MOE][FAP] as 1 wt% additive to a polyalphaolefin (PAO 6) in the lubrication of CrN PVD coating. The tribological behavior of this mixture has also been compared with a traditional oil additive, such as zinc dialkyldithiophosphate (ZDDP). Friction and wear tests were performed by means of a ball-on-plate reciprocating tribometer, and XPS was used to analyze wear surfaces. The experimental results showed that both additives substantially improve the anti-friction and anti-wear performance of the base oil. However, the tribological behavior of the ionic liquid as oil additive does not reach that of ZDDP. The interactions of each additive with the surface and tribofilm formation contributed to improve the tribological behavior of the lubricants.

Lubrication of TiN, CrN and DLC PVD Coatings with 1-Butyl-1-Methylpyrrolidinium tris(pentafluoroethyl)trifluorophosphate

This article studies 1-butyl-1-methylpyrrolidinium tris(pentafluoroethyl)trifluorophosphate ionic liquid ([BMP][FAP]) as neat lubricant and 1 wt% additive to a polyalphaolefin (PAO 6) in the lubrication of TiN, CrN and diamond-like carbon (DLC) PVD coatings. Friction and wear tests were made using a ball-on-plate reciprocating tribometer under high-pressure conditions. Experiment results showed a slight friction reduction with the use of the [BMP][FAP] ionic liquid as oil additive compared with test made with neat PAO 6. [BMP][FAP] as neat lubricant provoked the lowest friction coefficients and an important wear reduction. Interactions of the ionic liquid with the surface and tribofilms formation contributed to the increase in the load-carrying capacity.

Voltammetric Studies with Adhered Microparticles and the Detection of a Dependence of Organometallic Cis+→ Trans+First-Order Isomerization Rate Constants on the Identity of the Ionic Liquid

Voltammetric studies employing electrode surfaces modified with microparticles of redox active solid can be used conveniently to obtain thermodynamic and kinetic information in ionic liquids in cases where a first-order chemical reaction of rapidly dissolved electrolyzed product is coupled to the electron-transfer process. Experimental and theoretical verification of this concept is provided. A study based on the voltammetric oxidation of durene (J. Phys. Chem. A 2003, 107, 745) to its cation radical contains a first-order followup chemical reaction that is almost independent of whether organic solvent (electrolyte) or ionic liquid media are used. In contrast, it has now been found that the rate constants (kf) for the first-order cis+ → trans+ isomerization reactions that accompany the one-electron oxidation of microparticles of the organometallic compounds cis-[Mn(CN)(CO)2{P(OPh)3}(DPM)] (DPM = Ph2PCH2PPh2) or cis-[W(CO)2(DPE)2] (DPE = Ph2PCH2CH2PPh2) depend significantly on the identity of the ionic liquid. In the case of trihexyl(tetradecyl)phosphonium tris(pentafluoroethyl)trifluorophosphate ionic liquid, kf is similar to the value found in conventional organic solvent (electrolyte) media, but significantly faster than that in the ionic liquids, 1-butyl-3-methylimidazolium hexafluorophosphate, (1-ethyl-3-methylimidazolium)bis[(trifluoromethyl)sulfonyl]amide, and (N-butyl-N-methylpyrrolidinium)bis[(trifluoromethyl)sulfonyl]amide. No simple correlation of kf values with the physical or chemical properties of these ionic liquids has been elucidated.