Vapor Pressure Measurements Research Articles

Thermodynamics of the Cu–Bi system determined by vapour pressure measurements

Application of Knudsen method for solid and liquid copper in the temperature range 1300–1725K, liquid bismuth in temperatures 769–1129K, and liquid Cu–Bi alloys in temperatures from 871 to 1469K, provided experimental data which made it possible to characterize thermodynamic properties of liquid and gaseous phase of Cu–Bi system. Standard enthalpies of copper and bismuth monomers sublimation and dissociation of bismuth dimer as well as parameters of Regular Associated Solution model (RAS), describing excess Gibbs energy of liquid phase of the examined system, were determined. The obtained model takes into account also presence of disturbances in vaporization of bismuth dimer from Cu–Bi alloys by introducing into the model a parameter which describes the evaporation coefficient of that particle.

O72] Vapor pressure measurements of LiF-ZrF4 for Molten Salt Fast Reactor

O72] Vapor pressure measurements of LiF-ZrF4 for Molten Salt Fast Reactor

Description and Test of a New Multilayer Thin Film Vapor Deposition Apparatus for Organic Semiconductor Materials

In this work the description, test, and performance of a new vacuum apparatus for thin film vapor deposition (ThinFilmVD) of organic semiconductor materials are presented. The apparatus is able to fabricate single, multilayer/composites, or hybrid thin films using four independent, organic or inorganic, vapor deposition sources (Knudsen cells type), and the vapor mass flow is condensed onto a substrate surface (temperature regulated). The same apparatus could be also used to measure vapor pressures according to the Knudsen effusion methodology. Vapor pressures and thermodynamic properties of sublimation measured by Knudsen effusion of some reference organic materials (benzoic acid, anthracene, triphenylene, benzanthrone, 1,3,5-triphenylbenzene, perylene) were used to evaluate and test the performance of the apparatus. Moreover, nanostructures of thin films and composite materials of relevant charge transport and electroluminescent materials were deposited onto an indium–tin oxide (ITO) surface, and the mo...

Apparatus to measure the vapor pressure of slowly decomposing compounds from 1 Pa to 105 Pa.

This article describes an apparatus and method for measuring vapor pressures in the range from 1 Pa to 105 Pa. Its three distinctive elements are : (1) the static pressure measurements were made with only a small temperature difference between the vapor and the condensed phase, (2) the sample was degassed in situ, and (3) the temperature range extended up to 200 °C. The apparatus was designed to measure metal-organic precursors, which often are toxic, pyrophoric, or unstable. Vapor pressures are presented for naphthalene, ferrocene, diethyl phthalate, and TEMAH (tetrakisethylmethylaminohafnium). Also presented are data for the temperature-dependent decomposition rate of TEMAH.

Correcting "static" measurements of vapor pressure for time dependence due to diffusion and decomposition.

The static method for measuring vapor pressure assumes that the sample is pure and that its temperature is steady and uniform. In practice, the measured pressure may be time dependent due to evaporative cooling after pumping on the sample, transpiration of the sample in a temperature gradient, or diffusion of an impurity out of the sample. An impurity cannot be avoided if the sample is decomposing. This article identifies and quantifies various causes of time dependence, and it includes an analysis that can obtain the vapor pressure from the time-dependent pressure of a decomposing sample. The analysis was applied to measurements of TEMAH (tetrakisethylmethylaminohafnium), whose decomposition continuously generated a volatile impurity. The corrected vapor pressures obtained for three TEMAH samples at 39 °C agreed to within ±1 %, even though the partial pressure of the impurity was as much as 7 times larger.

Vapor Pressure of Hexamethylene Triperoxide Diamine (HMTD) Estimated Using Secondary Electrospray Ionization Mass Spectrometry.

A rapid method for vapor pressure measurement was developed and used to derive the vapor pressure curve of the thermally labile peroxide-based explosive hexamethylene triperoxide diamine (HMTD) over the temperature range from 28 to 80 °C. This method uses a controlled flow of vapor from a solid-phase HMTD source that is presented to an ambient-pressure-ionization mass spectrometer equipped with a secondary-electrospray-ionization (SESI) source. The subpart-per-trillion sensitivity of this system enables direct detection of HMTD vapor through an intact [M + H](+) ion in real time at temperatures near 20 °C. By calibrating this method using vapor sources of cocaine and heroin, which have known pressure-temperature (P-T) curves, the temperature dependence of HMTD vapor was determined, and a Clausius-Clapeyron plot of ln[P (Pa)] vs 1/[T (K)] yielded a straight line with the expression ln[P (Pa)] = {(-11091 ± 356) × 1/[T (K)]} + 25 ± 1 (error limits are the standard error of the regression analysis). From this equation, the sublimation enthalpy of HMTD was estimated to be 92 ± 3 kJ/mol, which compares well with the theoretical estimate of 95 kJ/mol, and the vapor pressure at 20 °C was estimated to be ∼60 parts per trillion by volume, which is within a factor of 2 of previous theoretical estimates. Thus, this method provides not only the first direct experimental determination of HMTD vapor pressure but also a rapid, near-real-time capability to quantitatively measure low-vapor-pressure compounds, which will be useful for aiding in the development of training aids for bomb-sniffing canines.

Vapor pressure measurements of PbBr2 by the Knudsen effusion method and identification of its vapor species

The vapor pressure of PbBr2 solid was measured by the Knudsen effusion method assuming that the vapor species consisted only of monomers. The vapor pressure of PbBr2 fitted the following linear equation over the temperature range 532.3–633.9K:ln(p (Pa))=−(16,653±431)T (K)+(26.47±0.74).The standard sublimation enthalpy of PbBr2 was estimated to be 138.5±3.6kJmol−1, and the standard sublimation entropy was estimated to be 220.1±6.2Jmol−1K−1. Identification of the predominant vapor species of PbBr2 was conducted using mass spectrometry. From the analysis, the main vapor species of PbBr2 solid is the PbBr2 monomer.

R 347mcc の飽和蒸気圧力および飽和液体密度の測定

R 347mcc の飽和蒸気圧力および飽和液体密度の測定

Vapor pressure measurement of lead and lead chlorides in FeOT–CaO–SiO2–Al2O3 system

Vapor pressure of lead and lead chlorides from FeOT–CaO–SiO2–Al2O3 slag system was measured by using Knudsen effusion method. The results suggest that the vapor pressures of lead and lead chlorides increase with increasing temperature. For the slag systems without chlorine, the logarithm of vapor pressure (lnp) shows highly linear dependency on the reciprocal of temperature (1/T), and higher vapor pressure is observed in the condition where more metallic lead vapor is formed. In this case, the vapor pressure of lead increases with increasing slag basicity (w(CaO)/w(SiO2)), increasing FeO content and w(Fe2+)/w(Fe3+) ratio. For the case of slag system with chlorine addition, the total pressures of PbCl2 and PbCl increase with decreasing basicity and FeO content of slag.

HFE-7100 の飽和蒸気圧力および飽和液体密度の測定

HFE-7100 の飽和蒸気圧力および飽和液体密度の測定

Vapor pressures and thermophysical properties of selected monoterpenoids

A thermodynamic study of selected monoterpenoids, geraniol, β-citronellol, and borneol, is presented in this work. The vapor pressure measurements were performed using two static apparatus over a wide temperature range from 273 to 363K. Liquid heat capacities were measured by Tian–Calvet calorimetry in the temperature interval from 258 to 355K. The phase behavior was investigated by DSC from 183K. The thermodynamic properties in the ideal-gas state were calculated by combining statistical thermodynamics and density functional theory (DFT) calculations. Calculated ideal-gas heat capacities and experimental data on vapor pressure and condensed phase heat capacity were treated simultaneously to obtain a consistent thermodynamic description.

Measurements of Density, Viscosity, and Vapor Pressure for 1,1,1-Trifluoro-2,3-dichloropropane

The density and viscosity were measured in the temperature range of (273.15 to 333.15) K at atmospheric pressure, and the vapor pressure was measured at temperatures from (293.59 to 400.80) K for 1,1,1-trifluoro-2,3-dichloropropane. The expanded uncertainties in temperature, density, viscosity, and pressure measurements were estimated to be less than 20 mK, 0.0005 g·cm–3, 0.006 mPa·s and 1.2 kPa, respectively. A total of 31 density experimental points were obtained with 31 viscosity experimental points and 58 vapor pressure experimental points. Temperature-dependence correlation equations for the density, viscosity, and vapor pressure were proposed.

Vapor pressures and thermophysical properties of selected hexenols and recommended vapor pressure for hexan-1-ol

A thermodynamic study of selected unsaturated alcohols, cis-hex-3-en-1-ol, trans-hex-2-en-1-ol, and hex-1-en-3-ol, together with hexan-1-ol, is presented in this work. The vapor pressure measurements were performed using the static method over the environmentally important temperature range from 238 to 308K. Liquid heat capacities were measured by Tian–Calvet calorimetry in the temperature interval from 258 to 355K and were extended by controlled extrapolation by differential scanning calorimetry (DSC) toward the normal boiling point temperatures. The phase behavior was investigated by DSC from 183K. The thermodynamic properties in the ideal-gas state were calculated by combining statistical thermodynamics and density functional theory (DFT) calculations. Scaling factors were evaluated based on measured Raman and IR spectra. Calculated ideal-gas heat capacities and experimental data on vapor pressures, condensed phase heat capacities, and vaporization enthalpies were treated simultaneously to obtain a consistent thermodynamic description.

Extension of the DSC method to measuring vapor pressures of narrow boiling range oil cuts

An application of the standard test method for determining vapor pressure of pure compounds by thermal analyses (ASTM E 1782) was extended to vapor pressure measurements of narrow boiling range oil cuts by differential scanning calorimetry (DSC). The reliability of this application was examined by measuring comparable vapor pressure curves of selected narrow boiling oil cuts via a DSC based method and a static method. The oil cuts were distilled from a gasoline fraction (boiling range from about 363 to 453K) from oil shale retorting oil, which was produced from Estonian kukersite oil shale by the Galoter process. The representative DSC measurements presented cover the temperature range from 318 to 484K and pressure range from 15 to 750kPa. Based on the results of the study, the DSC based method (ASTM E 1782) can be suggested as an alternative approach for determining vapor pressures of narrow boiling range oil cuts, with advantages such as a small sample size, use of commercial equipment and no need for sample degassing.

Physical and Electrochemical Properties of Room-Temperature Ionic Liquids Containing Allyl-Based Phosphonium Cations and Bis(fluorosulfonyl)Amide Anion

Room-temperature ionic liquids (RTILs) have been developed for a wide variety of electrochemical applications due to their unique physicochemical properties such as favorable solubility of organic and inorganic compounds, relatively high ionic conductivity, no measurable vapor pressure, high thermal stability, low flammability, etc. Another advantage of RTILs is a designability of the chemical structures. Although many kinds of RTILs have been already investigated, interests in phosphonium RTILs have been increasing for their considerable advantages such as chemical and thermal stabilities. Recently, we have designed and proposed several RTILs based on quaternary phosphonium cations together with a bis(fluorosulfonyl)amide (N(SO2F)2 -, FSA) anion.1 We also reported several phosphonium RTILs containing unsaturated carbon-carbon bonds in combination with a bis(trifluoromethylsulfonyl)amide (N(SO2CF3)2 -, TFSA) anion.2 In this work, we demonstrate the physicochemical characterizations of the RTILs based on quaternary phosphonium cations containing an allyl group (Figure 1) together with a FSA anion.The preparation and purification of phosphonium RTILs were carried out according to the procedures described in our previously published papers.1,2 The phosphonium RTILs were prepared by aqueous ion exchange reactions of the precursor phosphonium bromides with lithium TFSA or potassium FSA. The resulting crude RTILs was extracted by dichloromethane, and then purified by washing with pure water several times until no residual bromide anion was detected with the use of AgNO3. The RTILs was dried under high vacuum for at least 8 h at 100 ◦C prior to use. The physicochemical and electrochemical properties such as conductivity (ac impedance method), viscosity (cone-plate type viscometer), density, melting point (DSC), thermal decomposition temperature (TGA) and electrochemical window (linear sweep voltammetry, LSV) were measured under dry argon atmosphere.Table 1 summarizes the physicochemical properties of the allyl-based phosphonium RTILs together with a FSA anion. When an allyl group was introduced into an alkyl chain of the phosphonium cation, such phosphonium RTILs exhibited lower viscosity and higher conductivity than the corresponding unsubstituted phosphonium RTILs. Similar results were obtained in the case of TFSA-based phosphonium RTILs.2 In this series of RTILs, P111(Al)-FSA showed the highest density, lowest viscosity and highest conductivity because of its smallest cation size. In addition, it was found that each RTIL showed lower melting point than that of the corresponding TFSA-based RTILs. This finding reveals that the combination of the phosphonium cations with FSA anion expands the temperature range of the RTILs. The electrochemical analysis by using a LSV technique suggested that the electrochemical windows tended to be somewhat reduced by introducing an allyl group; however, lithium deposition and dissolution in the RTILs was possible. The influence of the introduction of an allyl group on the thermal stability of the RTILs will be also reported and discussed.

Vapor Pressure of HFE 7100

The vapor pressure of HFE 7100 was measured from (306 to 431) K for pressures from (36 to 1180) kPa using a Burnett apparatus. The temperature measurement uncertainty was estimated to be ± 5 mK, and the pressure uncertainty was estimated to be ± 300 Pa. A Wagner-type equation was used for the vapor pressure of HFE 7100 based on the experimental data. This equation contains five coefficients and correlates the measured vapor pressures within 0.11 %.

Measurement, correlation, and prediction of vapor pressure for binary and ternary systems containing an alkylsulfate-based ionic liquid

Vapor pressure data for water, 1-propanol, 2-propanol, as well as the mixtures of {water+1-propanol} and {water+2-propanol}, were measured by a quasi-static ebulliometric method, in the presence of an alkylsulfate-based IL, namely, 1-ethyl-3-methylimidazolium methylsulfate ([EMIM][MS]) or 1-ethyl-3-methylimidazolium ethylsulfate ([EMIM][ES]). The experimental vapor pressure data for binary systems containing IL were correlated by NRTL model with an overall relative root mean square deviation (rRMSD) of 0.0053, and the obtained binary NRTL parameters were employed to predict the vapor pressure for two ternary systems with an overall rRMSD of 0.0196. In addition, isobaric vapor–liquid equilibria were predicted for the ternary systems containing [EMIM][MS], [EMIM][ES], 1,3-dimethylimidazolium methylsulfate ([MMIM][MS]), 1-ethyl-3-methylimidazolium tetrafluoroborate ([EMIM][BF4]), and 1-ethyl-3-methylimidazolium trifluoromethanesulfonate [EMIM][OTf], respectively, with IL mole fraction of 0.05, 0.15, and 0.25 at 101.325kPa. It was found that the addition of IL can enhance the relative volatility of propanol to water, and the separation ability follows the order of [MMIM][MS]>[EMIM][MS]>[EMIM][ES]>[EMIM][BF4]>[EMIM][OTf], which was further explained at electronic level with quantum chemical calculation. Therefore, the azeotropic mixtures of {water+1-propanol}, and {water+2-propanol} might be separated effectively by the addition of the alkylsulfate-based ILs in extractive distillation.

R 245fa の飽和蒸気圧力と飽和液体密度の測定

R 245fa の飽和蒸気圧力と飽和液体密度の測定

Determination of oxygen stoichiometry of oxide fuel during high temperature vapour pressure measurement

This study presents an original approach of oxygen stoichiometry determination during high temperature (>2000K) measurements of vapour pressure using the Knudsen effusion mass spectrometry technique. The method has been developed taking into account the vapour pressure measurements of series of (U1-x,Pux)O2-δ samples with x(Pu)=0.25, 0.5, 0.75 together with pure UO2-δ and PuO2-δ end-members coupled with equilibrium calculations based on thermodynamic assessment of the U–Pu–O system. The presented method consists of two steps; in the first step the oxygen potential of the oxide phase is determined based on the measured partial vapour pressures of UO(g), UO2(g), PuO(g) and PuO2(g) gaseous species and during the second step the thus determined oxygen potential is linked with the matching oxygen stoichiometry of the sample. From the obtained results it has been demonstrated that it is possible to accurately estimate the oxygen stoichiometry of the mixed oxide fuel samples knowing the description of the oxygen potential of the corresponding end-members only.

Screening of Ionic Liquid/H2O Working Pairs for Application in Low Temperature Driven Sorption Heat Pump Systems

Due to the known corrosion and crystallization issues of LiBr/H2O, the state-of-the-art working pair in sorption heat pump (SHP) systems, research into alternative working pairs is of high practical relevance. We have studied a wide range of ionic liquids (ILs) for this application in order to find potential new systems with enhanced performance. The screening was conducted with a focus on vapor pressure measurements of, in total, 74 examined working pairs. As common vapor–liquid-equilibrium measurements are very precise but rather time-consuming, we developed a new setup allowing a fast relative determination of humidities with very small sample volumes for screening purposes. By this method we identified seventeen IL/H2O working pairs fulfilling the technical relevant criterion of a water vapor pressure pH2O ≤ 10 mbar at T = 308 K with an IL content of less than 80 wt % (wIL < 0.8). Further evaluation of these candidates with respect to their thermal stability and viscosity allowed us to identify [MMIM]...