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Pyrolysis is one of the potential way for the degradation of hydrofluorocarbons, but it is difficult to make effective use of the complex pyrolysis products. The addition of plastics can provide sufficient hydrogen source for the degradation of hydrofluorocarbons to generate the high value-added chemicals and fuels. Density functional theory calculation and reactive molecular dynamic simulation are employed to investigate the co-pyrolysis mechanism of 1,1,1,2-tetrafluoroethane and low-density polyethylene in this work. The results show that the H atoms provided by low-density polyethylene promote the defluorination reactions of 1,1,1,2-tetrafluoroethane to generate HF and short chain hydrocarbons, and the number of F atoms in HF molecules accounted for nearly 80 % of the whole reaction system, achieving a better defluorination effect. The defluorination rate of 1,1,1,2-tetrafluoroethane and plastics co-pyrolysis is more than 5 times that of pure 1,1,1,2-tetrafluoroethane pyrolysis. The main co-pyrolysis products of 1,1,1,2-tetrafluoroethane and low-density polyethylene are H 2 , HF and short chain hydrocarbons, the purpose of hydrofluorocarbons degradation into high value-added chemicals and fuels is realized in this study. This work provides a green, effective way for the conversion waste hydrofluorocarbons and waste plastics into high value-added chemicals and fuels, and achieves the conversion of waste hydrofluorocarbon refrigerants to more economical products. • Co-pyrolysis mechanism of hydrofluorocarbons and plastic is first time studied. • Co-pyrolysis process of 1,1,1,2-tetrafluoroethane and low-density polyethylene is described. • Plastic as a hydrogen donor promotes the defluorination of 1,1,1,2-tetrafluoroethane. • HF, H 2 and short chain hydrocarbons rich products could be selectively obtained. • Pyrolysis products of waste hydrofluorocarbons can be enhanced by adding plastics. [ABSTRACT FROM AUTHOR]

[Display omitted] • The strong interactions between R-1234yf and R-134a in R-513A were between C atoms (-CF 3 groups). • The vdW interaction of refrigerant-anion was proportional to the solubility of R-134a/R-1234yf in nitrile-based ILs. • Nonbonding interactions vary between R-134a-anion and R-1234yf-anion, impacting nitrile-based IL selectivity. • R-134a and R-1234yf had strong interactions with the N atoms in the anions of nitrile-based ILs. The reclamation of mixed refrigerants stands as a potent measure to substantially mitigate the emission of fluorinated gases (F-gases). In the separation of the azeotropic refrigerant R-513A (comprising 56 wt% R-1234yf, 2,3,3,3-Tetrafluoropropene, and 44 wt% R-134a, 1,1,1,2-Tetrafluoroethane), the extractive distillation process using ionic liquids (ILs) was employed. The molecular structure of nitrile-based ILs ([C 4 C 1 im][SCN], [C 4 C 1 im][N(CN) 2 ], [C 4 C 1 im][C(CN) 3 ], [C 4 C 1 im][B(CN) 4 ]) exerts a regular impact on the solubility of refrigerants, thereby necessitating molecular dynamics simulation to ascertain the law of refrigerant solubility in ILs concurrent with the augmentation in the number of –CN in the anion. Additionally, an analysis was conducted to elucidate the mechanism underlying the high selectivity of nitrile-based ILs. The results revealed pronounced interactions between R-1234yf and R-134a, predominantly occurring between carbon atoms (-CF 3 groups in R-134a and R-1234yf), and chiefly van der Waals interactions. An enhancement in the number of –CN in anion led to the fortification of the van der Waals interaction between R-134a/R-1234yf and the anion. The stronger nonbonding interaction energy between R-134a and the anion, as well as the higher radial distribution function (RDF) peak height between R-134a and the anion, signified a more robust interaction between R-134a and the anion compared to R-1234yf and the anion. Concurrently, the variance in the RDFs in the anion-C atom (-CH 2 F group in R-134a and -CF group in R-1234yf) revealed the selectivity of the four ILs to R-134a and R-1234yf. Among the four anions, [B(CN) 4 ]− exhibited the most interaction sites with R-134a. This investigation contributes significantly to comprehending the interaction mechanism of azeotropic refrigerants and the interaction mechanism between refrigerants and nitrile-based ILs. [ABSTRACT FROM AUTHOR]

This paper presents an experimental study of an adiabatic flow of R-134a through a capillary tube. The paper discusses the details of experimental facility for testing a capillary tube with sub-cooled and two phase inlet conditions of R-134a. The effect of diameter, capillary length, inlet refrigerant quality and inlet pressure on mass flow rate were investigated. The experiments for testing the capillary tubes were proceeded by an integrity test. The vapour quality varied from 0.05 to 0.25. All the experiments were done by varying the pressure from 655 to 724 kPa. The effect of two phase inlet conditions on mass flow rate of R-134a through an adiabatic capillary tube is observed. A correlation to predict the mass flow rate of refrigerant flowing through an adiabatic capillary tube is proposed for two phase inlet conditions. The proposed correlation predicts the measured data with an error band of ±25%. [ABSTRACT FROM AUTHOR]

A nano-composite from biologically obtained chitin nanofillers homogenously dispersed in a poly( ε -caprolactone) matrix was successfully achieved by an ultrasonication-assisted non-toxic and non-aqueous methodology. For this purpose, biological chitin was obtained from lactic acid fermentation of shrimp wastes and converted into chitin whiskers by acidic hydrolysis in a novel process at low temperature (4 °C) that enhanced the distribution and yield. Additionally, the polyester matrix was enzymatically produced in a non-toxic compressed fluid (1,1,1,2-tetrafluoroethane at 25 bar and 65 °C) medium. The homogeneous distribution of the nanofiller in the matrix was corroborated by confocal and atomic force microscopies. Films of the nanocomposite were physicochemically characterized to assess its adequate properties. Additionally, the qualitative viability of human fibroblasts and osteoblasts cells was studied on the produced nanocomposite films showing good biocompatibility. [ABSTRACT FROM AUTHOR]

Rutin is a common dietary flavonoid that has been widely consumed in pharmaceutical industry. To facilitate the extraction of rutin from plant tissues, we determined the solubility of rutin in supercritical carbon dioxide by dynamic method at 313.2–343.2 K over the pressures range of 9.0–18.0 MPa and in subcritical 1,1,1,2-tetrafluoroethane (R134a) by static method at 313.2–343.2 K over the pressures rang of 7.0–18.0 MPa. The experimental results indicate that the extraction of rutin should be operated by subcritical R134a or supercritical CO 2 below or above the transition pressure (the pressure at which the rutin solubilities in subcritical R134a and supercritical CO 2 are the same), respectively. Furthermore, the solubility data were satisfactorily correlated by Chrastil model and m-ER&HV model (modified Esmaeilzadeh–Roshanfekr equation of state combined with Huron–Vidal mixing rule), and the thermodynamic consistency of the solubility data was confirmed by the thermodynamic consistency test. [ABSTRACT FROM AUTHOR]

Nano α-aluminum fluorides with high surface area were synthesized by a simple ethylene glycol mediated sol–gel technique using dilute aq. HF as the F source, and their performances were investigated for gas-phase dehydrofluorination of 1,1,1,2-tetrafluoroethane at relatively low reaction temperature (400 °C). Aluminum precursor was crucial for the phase composition, textural and acidic properties of the resulting fluoride. Commercially low-cost and available inorganic Al was firstly used as precursor for synthesis of aluminum fluorides via the sol–gel route, and the as-prepared α-AlF 3 possessed high surface area (up to 170 m 2 g −1 ) and strong surface acidities even after thermal treatment of 400 °C. The presence of sulfate ions suppressed the crystallization of aluminum fluoride during calcination when Al 2 (SO 4 ) 3 was used as precursor, leading to an amorphous phase for as-prepared AlF 3 . Aluminum fluorides with β and pyrochlore phase were prepared using aluminum isopropoxide and aluminum diacetate hydroxide, respectively, as precursors. Based on the results of IR, XRD and element analysis, it is concluded that the formation of Al-glycolates during the sol–gel process can effectively reduce the hydrolysis of precursor and suppress particle agglomeration, thus leading to dominant formation of nano aluminum fluorides. The residual O derived from minor hydrolysis can resist sintering under high-temperature treatment, which is a key factor to improve the thermostability of as-prepared aluminum fluoride. Due to their large Lewis acidic amounts, the α-AlF 3 derived from AlOOH and Al 2 O 3 exhibited remarkably high catalytic activity with CF 3 CH 2 F conversion of 24%–28% and CF 2 =CHF selectivity above 98%, which were far higher than that of AlF 3 prepared by traditional methods. [ABSTRACT FROM AUTHOR]

This paper presents the comparative analysis of HFO1234ze(E) and HFC134a during vaporisation inside a 4 mm smooth tube. The experimental tests were carried out at three different saturation temperatures (10, 15, and 20 °C) at increasing vapour quality up to incipient dryout to evaluate the specific contribution of heat flux, refrigerant mass flux, mean vapour quality, and saturation temperature (pressure). The heat transfer coefficients have a positive slope versus vapour quality and the slope increases with refrigerant mass flux and decreases with heat flux. Saturation temperature (pressure), refrigerant mass flux and mean vapour quality have a remarkable impact on the frictional pressure drop of both HFO1234ze(E) and HFC134a whereas the effect of heat flux appears marginal or negligible. Convective boiling seems to be the prevailing heat transfer regime in the present experimental tests. HFO1234ze(E) exhibits heat transfer coefficients similar to HFC134a and slightly higher frictional pressure drops. [ABSTRACT FROM AUTHOR]

Supermarket chains require benchmarking and analysing refrigeration performance in order to manage their energy efficiency investments. This paper contributes in robustly assessing refrigeration system energy and carbon performance in which commonly believed drivers are used to conduct correlations. Based on this, refrigeration connected load, store opening hours and external temperature were found to construct a more representative energy performance indicator (EPI) than other metrics. By using such an indicator, it is possible to identify poor performing systems from an estate portfolio and thus select sites suitable for energy saving measures. Furthermore, energy impact from introducing natural refrigerants is examined using empirical data from a UK supermarket chain. It was found that CO 2 systems have different seasonal performance than HFC systems, nonetheless on an annual basis no system has a clear edge over another. Lastly, other initiatives such as cabinet night blinds and suction pressure optimisation achieved 10% and 7% energy reduction respectively. [ABSTRACT FROM AUTHOR]

In this work, the use of homogenous media composed of the ionic liquid [C4MIM] [PF6] in combination with miscible compressed 1,1,1,2-tetrafluoroethane (R134a), above the critical points of the mixture, at 338.15 and 363.15 K and pressure of 30,000 kPa, lead to the successful enzyme-mediated syntheses of linear and hyperbranched poly- l -lactides. The attained polymer molecular weights were higher than those in previous reports using compressed fluids, even in the supercritical state, or individual ionic liquid media. The maximum attained M n for linear PLLA in this work was 28,000 g/mol, and that for hyperbranched was 11,200 g/mol which were up to 3-fold higher than those obtained with the ionic liquid medium, and this is attributed to favored reaction media characteristics in this critical/miscible system. Additionally, non-enzymatic propagation side mechanisms were minimized or eliminated with the addition of the green compressed R134a. [ABSTRACT FROM AUTHOR]

A low temperature (176 K), high resolution far-IR spectrum of 1,1,1,2-tetrafluoroethane (HFC-134a) has been recorded at the Australian Synchrotron Far-IR beamline. The ν 8 band, located at 665.62 cm −1 , has been analysed and 4635 ro-vibrational transitions were assigned and confirmed using ground state combination differences. Local perturbations emanating from two interacting dark states were identified, and subsequently treated using two c -axis Coriolis coupling terms. The necessary modifications of a collisional cooling/enclosive flow cooling cell for synchrotron far-IR spectroscopy are outlined. [ABSTRACT FROM AUTHOR]

High-resolution infrared absorption cross sections for 1,1,1,2-tetrafluoroethane have been determined over the spectral range 750–1600 cm −1 from spectra recorded using a high-resolution FTIR spectrometer (Bruker IFS 125HR) and a 26-cm-pathlength cell. Spectra of 1,1,1,2-tetrafluoroethane/dry synthetic air mixtures were recorded at 0.015 cm −1 resolution (calculated as 0.9/MOPD) at a number of temperatures and pressures (22–761 Torr and 191–296 K) appropriate for atmospheric conditions. Intensities were calibrated using composite 1,1,1,2-tetrafluoroethane spectra taken from the Pacific Northwest National Laboratory (PNNL) IR database. This cross section dataset is intended to replace what is currently available in the HITRAN/GEISA databases. [ABSTRACT FROM AUTHOR]

Many vehicle owners in the United States recharge their vehicles' air conditioning systems with small containers of hydrofluorocarbon-134a (HFC-134a, CH 2 FCF 3 ), at a frequency estimated to be once every year on average. Such nonprofessional service produces immediate emissions of this potent greenhouse gas during service and from the residual heel in partially used containers. The nonprofessional operations are also associated with increased delayed refrigerant emissions that occur because owners are less likely to repair leaks than professional technicians. In California, an estimated 1.3 million nonprofessional service operations performed each year generate 0.27 ± 0.07 million metric ton CO 2 equivalent (MMTCO 2 e) of immediate emissions and 0.54 ± 0.08 MMTCO 2 e of delayed emissions, using a Global Warming Potential of 1300 for HFC-134a. The immediate emissions can be largely mitigated by a regulation that requires self-sealing valves and improved labeling instructions on the containers, a deposit-return-recycling program for the containers, and a consumer education program. If 95% of the used containers were to be returned by consumers for recycling of the container heel, the annual immediate emissions would be reduced by 0.26 ± 0.07 MMTCO 2 e. In the United States, an estimated 24 million nonprofessional service operations are performed each year, generating 5.1 ± 1.4 MMTCO 2 e of immediate emissions and 10.4 ± 1.5 MMTCO 2 e of delayed emissions. Mitigation measures equivalent to the California regulation would reduce nationwide immediate emissions by 4.9 ± 1.4 MMTCO 2 e, if 95% of the used cans were returned for recycling. These business-as-usual emissions and mitigation potentials are projected to stay approximately constant until around 2022, and remain at significant levels into the 2030s. [ABSTRACT FROM AUTHOR]

The fluorocarbon films were synthesized by radio frequency pulsed 1, 1, 1, 2-tetrafluoroethane plasma polymerization using various duty cycles. The deposition rates and water contact angles were examined for radio frequency pulsed plasma polymerized fluorocarbon films. The film surface properties were also determined by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and scanning electron microscopy. For varying duty cycle from 100% to 10% in pulsed plasma process, the plasma polymerized film drastically changed the surface property. Specifically, it has been observed that modulated plasmas with the proper duty cycle of 10% lead to the formation of the super-hydrophobic film by static water contact angle value of 150°. The surface properties of fluorocarbon films were determined as the Cassie state. In the transmittance, UV–VIS transmission spectra showed that these radio frequency pulsed plasma polymerized coatings were transparent in visible light region. By adjusting duty cycles in relation to radio frequency pulsed plasma polymerization, the hydrophobicity of the resulting thin fluorocarbon films could be tuned. [ABSTRACT FROM AUTHOR]

Abstract: R-134a (C2H2F4) is a low cost, easily available and chlorine free refrigerant, which in its superheated state can be used as an efficient neutron detector. Due to its high solubility in water the R-134a based superheated droplet detectors (SDD) are usually very unstable unless the detector is fabricated using a suitable additive, which stabilizes the detector. The SDD is known to have superheated droplets distributed in a short-lived and in a relatively long-lived metastable states. We have studied the detector response to neutrons using a 241AmBe neutron source and obtained the temperature variation of the nucleation parameters and the interstate kinetics of these droplets using a two-state model. [Copyright &y& Elsevier]

Abstract: Focusing on the effective use of low-grade solar heat as heat source to provide refrigeration for residential and commercial space cooling, an absorption-compression hybrid refrigeration cycle has been studied on the basis of available data of working pair 1,1,1,2-tetrafluoroethane (R134a) and dimethylformamide (DMF). In order to investigate their performance, the energy saving mechanism of the hybrid cycle was analyzed, by means of thermodynamic diagrams of log p–T, log p–h and T–s. The results show that the hybrid refrigeration cycle has a relatively high thermodynamic perfectibility and can use low-grade heat to replace parts of mechanical work for obtaining lower temperature refrigeration effect owing to its energy complement and cascade refrigerating configuration between the internal sub-cycles. Moreover, on the basis of two new criteria, the heat powered coefficient of performance and the electricity saving rate, the competition behavior between the sub-cycles of the hybrid cycle, i.e. the trade-off effects of compressor pressure on the low-grade heat utilization performance were also investigated. It was found that the sub-cycles compete in their contribution to the hybrid refrigeration system and the cycle preferences depend on the dominance which one achieves. In other words, there is an optimum compressor outlet pressure region under specified working conditions, where the hybrid refrigeration cycle has the maximum heat powered coefficient of performance and electricity saving rate. [Copyright &y& Elsevier]

Abstract: A simple, rapid and sensitive method was developed for determination of 17α-methyltestosterone in aquatic products by extraction with subcritical 1,1,1,2-tetrafluoroethane (R134a) extraction and high performance liquid chromatography (HPLC). Response surface methodology (RSM) was adopted to optimise extraction pressure, temperature and co-solvent volume. The optimum extraction conditions predicted within the experimental ranges were as follows: pressure 5MPa, temperature 31°C, and co-solvent volume 3.35ml. The analysis was carried out on XDB-C18 column (4.6mm×250mm, 5μm) with the mobile phase acetonitrile–water (55:45, v/v), flow rate 0.8ml/min, temperature 30°C and wavelength 245nm. Good linearity of detection was obtained for 17α-methyltestosterone between concentrations of 50–250ng/ml, r 2 =0.999. The method was validated using samples fortified with 17α-methyltestosterone at levels of 10, 30 and 50ng/g, the mean recovery exceeds 90%, and the RSD values were less than 10%. [Copyright &y& Elsevier]

Abstract: A family of modified van der Waals equations of state (vdW EOS) is extremely useful for many industrial applications. For example, the generic Redlich–Kwong (RK) EOS or its modification by Soave (SRK EOS) and Peng–Robinson (PR EOS) are still of popular use in industry to the present day. These two most popular (“cubic”) EOSs are based on modifications [1/(V 2 + bV), or 1/(V 2 +2bV − b 2)] of the volume dependence on the attractive part of the original van der Waals EOS [1/V 2] and also modifications of the temperature dependence of the attractive “a(T)” parameter of the original EOS (constant a). It is extremely rare in actual EOS applications to use the volume dependence of the original van der Waals EOS. In the present phase equilibrium calculations, we employ such a generic vdW EOS, P = RT/(V − b)− a(T)/V 2, with our well-tested mixing rule for multi-component mixtures. Using the same form of the “a(T)” parameter and the mixing rule, it has been found that all generic RK, PR, and vdW EOSs can present the phase behaviors (temperature–pressure–composition diagrams) equally well. It is shown that experimental gas solubility data (CO2, CF3–CFH2, SO2, and NH3) in room-temperature ionic liquids are well correlated with the present EOS model, and also that the phase behaviors such as LLE (liquid–liquid separations) are satisfactorily predicted. [ABSTRACT FROM AUTHOR]

Abstract: The composition, microstructure and growth kinetics of the surface film formed on molten ZK60 magnesium alloy in 1,1,1,2-tetrafluoroethane/air mixture were investigated by using SEM, EDS, XRD, XPS and TG. The results show that the film formed in 0.01% 1,1,1,2-tetrafluoroethane/air was non-protective, and its phase composition changed with melt temperature. At 760°C, the film was mainly composed of MgO and some MgF2 and ZrO2, whereas at 660°C it consisted mainly of MgO and Mg3N2. The film formed in air containing 0.1% 1,1,1,2-tetrafluoroethane or higher was comprised of MgF2 and C with small amounts of MgO, and it was protective. [Copyright &y& Elsevier]

Abstract: The oxidation behaviors of AZ91D magnesium alloy in 1,1,1,2-tetrafluoroethane/air atmospheres at temperatures between 660°C and 760°C have been studied. The experimental results show that with the increase of melt temperature, the oxidation rate of molten AZ91D magnesium alloy in 1,1,1,2-tetrafluoroethane/air atmospheres increased and the oxidation kinetics changed from parabolic law to linear law. On the other hand, the amount of MgF2 in the oxide film formed on AZ91D decreased, and the amount of MgO increased. The effect of melt temperature on the oxidation behaviors is primarily related to the relative content of MgO and MgF2 in the film, as well as the diffusion rate and the evaporation rate of magnesium through the film. [Copyright &y& Elsevier]

Abstract: The hydrogen abstraction reaction of 1,1,1,2-tetrafluoroethane (HFC-134a) by chlorine radical is investigated by theoretical calculations. Equilibrium geometries and harmonic vibrational frequencies of the reactants, transition state, and products are calculated using high-level ab initio methods. Rate constants of forward and backward reactions for the temperatures from 200 to 1000K are calculated using classical transition state theory with Eckart tunneling correction, fitted in the expressions kf (T)=1.19×10−23 T 3.93exp (−1110/T), and kb (T)=8.86×10−24 T 3.32exp (−959/T)cm3 molecule−1 s−1 for forward and backward reactions, respectively, and are in reasonable agreement with the available experimental values. [Copyright &y& Elsevier]

Abstract: During the melting and casting of magnesium and its alloys, it must be taken appropriate protective measures to prevent the melt from oxidizing and burning, because magnesium is a very active and readily ignitable element. In this paper, the morphologies and compositions of the surface films formed on magnesium and AZ91D alloy in air/1,1,1,2-tetrafluoroethane gas mixture at different conditions were investigated and analyzed by means of SEM, XRD and XPS. The experimental results showed that the morphologies and compositions of the surface films formed on molten magnesium and AZ91D alloy were different under the atmosphere of air containing different contents of 1,1,1,2-tetrafluoroethane. When the concentration of 1,1,1,2-tetrafluoroethane was less than 0.1vol.%, the surface films were mainly composed of MgO, and MgF2 for magnesium, and MgO, Mg3N2, AlN and MgAl2O4 for AZ91D alloy, which presented very coarse and incompact surfaces. When the concentration of 1,1,1,2-tetrafluoroethane was more than 1vol.%, the surface film on molten magnesium was not uniform, which was mainly composed of MgF2. The surface formed on molten AZ91D alloy was relatively smooth and compact, which was mainly composed of MgF2 and C. [Copyright &y& Elsevier]

Abstract: The hydrogen abstraction reaction of 1,1,1,2-tetrafluoroethane (HFC-134a) with hydroxyl radical is studied by theoretical calculations. Equilibrium molecular geometries and harmonic vibrational frequencies of the reactants, transition state, and products are calculated using high-level ab initio methods. Rate constants for the temperatures from 210 to 1000K are calculated using classical transition state theory with Eckart tunneling corrections, fitted in an expression k(T)=6.14×10−27 ×T4.70e(153/ T ) cm3 molecule−1 s-1, and are in reasonable agreement with the available experimental values. [Copyright &y& Elsevier]

Abstract: The vapour–liquid equilibria (p, T, x) of a 1,1,1,2-tetrafluoroethane+ethylene-glycol dimethylether mixture was measured using the static method in the temperature range (283.15–353.15)K in steps of 10K. The vapour–liquid equilibrium data were correlated by the temperature-dependent five-parameter non-random two-liquid (NRTL) equation. The data obtained in this experiment together with our previous experimental data for the binary system 1,1,1,2-tetrafluoroethane+triethylene-glycol dimethylether were used to calculate the UNIFAC interaction parameters for the CF3 and CH2F groups with the CH3, CH2, CH3O and CH2O groups. The resulting interaction parameters were used to predict the vapour pressures of the various mixtures studied in the literature. [Copyright &y& Elsevier]

Abstract: Fluorine substitution on a solute can have a significant effect on solute solubility in a given solvent and fluorine substitution on a solvent can also have a significant effect on solvent quality. The effect of fluorine is demonstrated with the phase behavior data for bis(p-tolyl)propane (BTP) compared to bis(p-tolyl)hexafluoropropane (BTHFP) in supercritical carbon dioxide, 1,1-difluoroethane (F152a), and 1,1,1,2-tetrafluoroethane (F134a). Semifluorinated BTHFP is more soluble than non-fluorinated BTP in all three solvents, especially CO2. The CO2–BTP system exhibits solid solubility behavior while the CO2–BTHFP system exhibits liquid–liquid–vapor (LLV) behavior near the critical point of CO2. Although the two dipolar hydrofluorocarbons (HFC) are better solvents than CO2 for these two aromatic solid compounds, F152a is the superior HFC solvent, especially for BTP, because F152a has a smaller molar volume and a larger effective dipole moment than F134a. LLV behavior is also observed for the F134a–BTP system near the critical point of F134a although the F134a–BTHFP, F152a–BTP, and F152a–BTHFP systems all appear to exhibit type-I phase behavior and no liquid–liquid immiscibility near the respective critical points. [Copyright &y& Elsevier]

Abstract: Isothermal vapor–liquid equilibrium data for the binary system of difluoromethane (HFC-32) +1,1,1,2-tetrafluoroethane (HFC-134a) were measured at temperature from 258.15 to 343.15K in a circulation-type equilibrium apparatus. The experimental data were correlated with the Peng–Robinson–Stryjek–Vera equation of state using the Wong–Sandier mixing rule. The overall deviation of the pressure by the PRSV equation of state was 0.940%, and the average deviation of vapor phase composition by the PRSV equation of state was 0.0063. [Copyright &y& Elsevier]

Abstract: The aim of this study was to determine the uptake and disposition of inhaled 1,1,1,2-tetrafluoroethane (HFC-134a) in humans. Ten male volunteers were exposed to 500ppm HFC-134a (2h, 50W exercise). The HFC-134a levels were monitored in blood, exhaled air and urine up to 19h post-exposure. The concentration in blood increased rapidly, reaching a plateau of 9.4±1.9μM (mean±S.D.) within 30min, followed by a fast post-exposure decrease. HFC-134a in expired air decreased rapidly as well and in parallel with that in blood. The post-exposure urinary excretion was 0.002% of the inhaled amount, and the half-time was 58min (pooled data). A physiologically based toxicokinetic (PBTK) model was developed for further analysis. Experimental and simulated time courses in blood and exhaled air agreed well in all 10 subjects. Further, the late decay in blood was consistent with a wash-out of HFC-134a from fat tissues, with a half-time of 114±21min. The simulated relative uptake during exposure was 3.7±0.5%. No remarkable findings were observed in the electrocardiographic recordings. Fibrinogen in plasma increased 1 day after exposure, whereas no effects on C-reactive protein, serum amyloid A protein, D-dimer or uric acid were seen. Further studies are needed to investigate the possible inflammatory response. [Copyright &y& Elsevier]

Abstract: A new multiparameter equation λ = λ(T, ρ) for the thermal conductivity of R134a has been developed from the available experimental data using a technique for the optimization of the functional form. The equation is valid in the temperature range from 200 to 540K and for pressure up to 70MPa, including also the near-critical region. The satisfactory performances of the equation are summarized by an average absolute deviation of 2.04% for the selected 5102 primary data points, with a significant improvement with respect to the present reference equation from the literature. The conversion of the independent variables of the experimental data into those of the equation, i.e. (T, P) into (T, ρ), is performed with a high accuracy equation of state for the fluid. [Copyright &y& Elsevier]

Abstract: The solubility and diffusivity of 1,1,1,2-tetrafluoroethane (R-134a) in seven room-temperature ionic liquids (RTILs) are presented. Among them, five of the RTILs were prepared for the first time with three new fluorocarbon sulfonate anions, and two were commercially available (1-butyl-3-methylimidazolium hexafluorophosphate was previously studied with R-134a). The gas absorption measurements were made using a gravimetric microbalance. Four isotherms (283.15, 298.15, 323.15, and 348.15K) were measured at pressures from 0.01 to 0.35MPa. Two of the newly synthesized ionic liquids, tetradecyl(trihexyl)phosphonium 1,1,2-trifluoro-2-(perfluoroethoxy)ethanesulfonate and tributyl(tetradecyl)phosphonium 1,1,2,3,3,3-hexafluoropropanesulfonate had the strongest interaction (negative deviations from Raoult''s Law) with R-134a. Experimental gas solubility data were successfully correlated with the nonrandom two-liquid (NRTL) solution model. The time-dependent absorption data was used to calculate diffusivities that were analyzed using a model based on a modified Stokes–Einstein equation. The derived molecular size for R-134a is 2–3 times larger than the known size. Magnitudes in the observed diffusion coefficients are 10−10 to 10−11 m2 s−1, which are about 10–100 times lower than typical values, found in various organic liquids. [Copyright &y& Elsevier]

A multi-layer feedforward neural network (MLFN) technique is adopted for developing a viscosity equation η=η(ρ,T) for R134a. The results obtained are very promising, with an average absolute deviation (AAD) of 0.63% for the currently available 571 primary data points, and are a significant improvement over those of a corresponding conventional equation in the literature. The method requires a high accuracy equation of state for the fluid in order to convert the experimental P, T into the independent variables ρ, T, but such an equation may not be available for the target fluid. Aiming at overcoming this difficulty, a viscosity implicit equation of state in the form T=T(η,P), avoiding the density variable, is developed for the liquid surface. The attained accuracy level is equivalent to that of the former equation. The proposed technique, being completely correlative and non theoretically founded, is also a powerful tool for experimental data screening. [ABSTRACT FROM AUTHOR]

• Ionic liquids can enable the recovery of HFCs and HFOs from refrigerant mixtures. • Small size and low fluorinated ionic liquids enhance HFC/HFO solubility selectivity. • High diffusion coefficients of hydrofluorocarbons in low-viscosity [C 2 mim][SCN] • Phase behavior accurately parametrized with NRTL activity model. The separation of hydrofluorocarbons (HFCs) and hydrofluoroolefins (HFOs) from novel refrigerant blends will become essential to boost the recycling of these compounds and drastically reduce the emission of HFCs, which are powerful greenhouse gases. In this work, the use of ionic liquids (ILs) as solvent media is explored to perform the selective separation of HFC/HFO refrigerant mixtures composed of the HFCs R32 (difluoromethane) and R134a (1,1,1,2-tetrafluoroethane) and the HFO R1234yf (2,3,3,3-tetrafluoropropene). The low-viscosity IL 1-ethyl-3-methylimidazolium thiocyanate, [C 2 mim][SCN], is selected as separation agent to prove that small and non-fluorinated ILs, with lower hydrogen bonding capability than other ILs, can provide enhanced solubility selectivity and mass transport properties for the selective separation of HFC/HFO refrigerant blends. The phase behavior of IL-refrigerant systems is determined at temperatures between 283.15 and 313.15 K and pressures up to 0.7 MPa. Results are parametrized according to the NRTL activity model and the separation selectivity is assessed in terms of Henry's law constants, solvation enthalpies and entropies, infinite dilution coefficients, Gibbs free energy of mixing, and ideal and noncompetitive selectivity. Results show superior HFC/HFO solubility selectivity in [C 2 mim][SCN] compared to other ILs due to unfavorable entropic effects that difficult the solvation of large molecules such as R1234yf. [ABSTRACT FROM AUTHOR]

With Al(NO 3) 3 ·9H 2 O as the Al precursor and PVDF as the fluorine source, freestanding AlF 3 sub-microspheres were fabricated following calcination, without the involvement of corrosive HF solution. With the varying of Al(NO 3) 3 ·9H 2 O to PVDF weight ratio, θ -AlF 3 and β -AlF 3 , α -AlF 3 were obtained respectively. The formation mechanism, morphology, surface properties and catalytic activities for the dehydrofluorination of 1,1,1,2-tetrafluoroethane to trifluoroethylene were investigated. During the fabrication process, Al(NO 3) 3 interacts with O=C bond in DMF. Meanwhile, DMF further interacts with CH 2 species in PVDF. Following calcination, PVDF decomposes to CO 2 and HF fluorinating Al species to AlF 3. The growth of AlF 3 crystal and particle are confined by PVDF. Consequently, θ -AlF 3 , β -AlF 3 and α -AlF 3 are achieved. At 450 °C, HFC-134a conversion of 23% and reaction rate of 1.9 mmol g−1 h−1 are approached over θ -AlF 3 catalyst. The reaction rate is almost 3 times higher than that of β -AlF 3 and is 40% higher than that of high surface area α -AlF 3 prepared by sol-gel method. No significant deactivation is observed in time on stream of 40 h. The stability is attributed to the interaction of AlF 3 with carbon frame work. The present study provides a scalable and facile synthesis route for AlF 3 spheres with controllable phase structures. Via simple calcination, θ -AlF 3 and β -AlF 3 , α -AlF 3 sub-microspheres are obtained respectively with Al(NO 3) 3 ·9H 2 O as the Al precursor and PVDF as the fluorine source, without the involvement of corrosive HF solution. Image 1 • AlF 3 sub-microspheres were fabricated via simple calcination of PVDF and Al(NO 3) 3. • Varying of Al(NO 3) 3 to PVDF weight ratio, θ -AlF 3 and β -AlF 3 , α -AlF 3 were obtained. • The interaction between Al(NO 3) 3 , DMF and PVDF controls the derived AlF 3 structure. • θ -AlF 3 shows high and stable activity for the pyrolysis of HFC-134a to TrFE. • It provides a facile synthesis route for AlF 3 with controllable phase structure. [ABSTRACT FROM AUTHOR]

The reaction of LDA (2.0 equiv.) with a THF solution of ZnCl2 (1.0 equiv.) and CF3CFH2 (HFC-134a) (1.2 equiv.) at 15–20°C gives a 73% yield of [F2C&z.dbnd6;CFZnCl]. Addition of R-C6H4I and Pd(PPh3)4 at rt to 65°C gives 61–86% yield of R-C6H4CF&z.dbnd6;CF2. [Copyright &y& Elsevier]