Webster B. Kay

Liquid-vapour equilibria in the iso-butanol—n-butanol, methanol—n-butanol and diethyl ether—n-butanol systems

Because of the paucity of data on the phase behaviour of mixtures of compounds containing active or polar groups at elevated pressure, the P-V-T-x relations of the iso-butanol-n-butanol, methanol—n-butanol and diethyl ether—n-butanol systems were determined at the liquid-vapour phase boundaries from near their atmospheric boiling points to the highest temperature and pressure at which the liquid and vapour co-exist. In addition, the vapour pressures and saturated liquid and vapour densities of the pure components were determined up to their critical points. The data are presented in the form of tables and graphs. In so far as is indicated by the data, the phase behaviour of binary systems of the alcohols is the same as that exhibited by binary systems of hydrocarbons that belong to a given homologous series.

The phase relations of binary systems that form azeotropes: N-alkyl alcohol-benzene systems: Methanol through n-butanol

Abstract The vapour-liquid P - V - T - x diagrams of the binary systems composed of methanol, ethanol, n-propanol and n-butanol with benzene as the common component, were determined over a temperature and pressure range which included the critical region. All systems form azeotropes which persist to the critical region except the ethanol-benzene system. The latter becomes nonazeotropic before a critical point is reached. The diagrams confirm the hypothesis proposed earlier, that systems which form azeotropes in the critical region are characterized by a pattern of phase behaviour distinctly different from that for nonazeotropic systems.

The critical constants of binary mixtures of certain perfluoro-compounds with alkanes

Abstract The critical temperature T c and critical pressure p c were measured at five compositions for each of five binary mixtures formed by propane with perfluoropropane, perfluoro- n -hexane, hexafluoroacetone, hexafluorobenzene, and trifluoroacetonitrile, and the two binary mixtures of n -hexane with perfluoro- n -hexane and hexafluorobenzene, and of perfluorocyclobutane with pentene-1. The composition dependences of T c and p c calculated by means of the modified theory of conformal solutions are in satisfactory agreement with the experimental results. In particular, the unusual S-shaped curve of p c against mole fraction for C 3 H 8 + CF 3 CN, predicted by the theory, is confirmed by the experimental results. The peculiar properties of mixtures of fluoro-compounds with inert solvents and the deviations from the harmonic mean rule for e 11 are discussed. Additionally, the densities of liquid (CF 3 ) 2 CO and the densities and vapor pressures of CF 3 CN were determined at reduced temperatures from about 0.6 to 1.

A (p, V, T) study of tetramethylsilane, hexamethyldisiloxane, octamethyltrisiloxane, and toluene from 423 to 573 K in the vapor phase

A Kay-type apparatus was used to measure (p, V, T) of gaseous tetramethylsilane, hexamethyldisiloxane, octamethyltrisiloxane, and toluene from about 423 K to 573 K. Second virial coefficients were computed for all temperatures. No experimental (p, V, T) values are reported in the literature for octamethyltrisiloxane. The present measurements constitute a significant extension of available results for hexamethyldisiloxane, since the only previous values were for lower temperatures. The results for tetramethylsilane resolved a conflict concerning the second virial coefficient. The results for toluene confirmed previous reports and served, along with the tetramethylsilane values, to verify our experimental and calculational procedures. Agreement of the second virial coefficients with existing literature values is satisfactory.

Vapor-liquid equilibria in binary mixtures formed from hexamethyldisiloxane, toluene and ethanol

Abstract Vapor-liquid equilibria have been measured in the binary systems hexamethyldisiloxane-toluene, hexamethyldisiloxane-ethanol and toluene-ethanol between 333.15 and 358.15 K and the results have been correlated using the Wilson equation. All three binary systems exhibit azeotropic behavior in the temperature range studied.

Critical-locus curves and liquid-vapor equilibria in the binary systems of benzene with carbon dioxide and sulfur dioxide

Critical-locus curves Tc(x) and Pc(x) have been determined for the carbon dioxide + benzene and sulfur dioxide + benzene systems. The data, together with existing liquid-vapor equilibrium data, are used to construct the complete phase diagrams at high pressures.

Critical properties of the vapor—liquid equilibria of the binary system acetone—n-pentane

Abstract Hajjar, R.F., Cherry, R.H. and Kay, W.B., 1986. Critical properties of the vapor—liquid equilibria of the binary system acetone— n -pentane. Fluid Phase Equilibria , 25: 137–146. The P—V—T—x properties for the acetone— n -pentane azeotrope-forming system have been measured by the technique developed by Kay. The experimental uncertainties have been estimated at 0.05 K , 2.4 kPa and 0.06% of the volume. The results for eight different compositions covering the range 180 to 200°C and 2.5 to 4.0 MPa are given. Smoothed critical loci have been plotted. The critical temperatures and pressures were correlated by a quadratic relationship of the form Q cm = Σ i Σ j x i x j Q cij where i , j = 1, 2. The maximum discrepancy in the critical temperature was 0.6 K and in the critical pressure was 0.012 MPa.

Determination of the critical constants of high-boiling hydrocarbons Experiments with gallium as a containing liquid

Abstract The critical temperature and pressure and the critical end-point temperature and pressure of n -nonane, n -decane, 1,3,5-trimethylbenzene, 1,2,4-trimethylbenzene, 1,2,3-trimethylbenzene, and naphthalene were measured with mercury and compared with the critical temperature and pressure of n -nonane, 1,2,4-trimethylbenzene, and naphthalene when measured with gallium. To within the accuracy of the measurements, the values of the critical temperature and pressure obtained with gallium and with mercury were the same. However, the chemical and physical properties of gallium are such as to make it very difficult to devise a procedure that would ensure highly accurate results. Its use as a confining liquid is therefore limited. The differences between the critical temperature and pressure of the pure compounds and critical end-point temperature and pressure of the binary mixtures of mercury + hydrocarbon, ΔT and Δp , respectively, show that the solubility of mercury has a relatively small effect ΔT on the critical temperature, whereas Δp , the partial pressure of mercury, is proportional to, but less than, the vapor pressure of pure mercury. A plot of log 10 ( Δp kPa ) against ( T K ) −1 gives a linear relation which serves as a method of estimating the partial pressure of mercury at a given temperature.

Phase equilibria in the n-hexane + diethylamine system

Abstract Pressure-temperature-composition data for the binary system composed of n-hexane and diethylamine have been determined over a range of conditions extending into the critical region. Dew, bubble and critical points at six compositions are reported in this paper. Vapor pressures and liquid densities of pure diethylamine are also reported. Phase equilibria in this nonpolar+polar system have been correlated using the Peng-Robinson (PR) equation. The PR equation is shown to work well for this weakly associating system although it fails to reproduce the detailed behavior of the critical locus. A remarkable feature of this binary system is that the critical locus is also the locus of points of maximum temperature (maxcondentherm) and pressure (maxcondenbar). As a consequence, there is no retrograde region in the system. The critical locus also exhibits a minimum in temperature which is characteristic of azeotropic behavior in the critical region.

Volume changes on mixing in the cyclohexane-n-heptane-benzene system

Abstract It is well known that when petroleum fractions of different boiling range are mixed, their volumes are not strictly additive. However, little effort has been made to investigate the effect of composition, chemical nature of the components, and temperature on the magnitude and sign of the deviation from additivity. In order to obtain information on these factors, but to avoid the difficulties attendant with the interpretation of the data on such a complex mixture as petroleum, a study was made of the ternary system, cyclohexane- n -heptane-benzene. Volume changes on mixing were computed from the specific volumes of the pure compounds and their binary and ternary mixtures which were determined experimentally at 60°F and 100°F. An increase in volume on mixing was noted in all mixtures studied, with the value of the maxima at 60°F ranging from about 0·30% in the case of a 60-40 mixture (by weight) of cyclohexane and n -heptane to 0·70% in the case of a 50-50 mixture of cyclohexane and benzene. In the ternary system a maximum of about 0·7% increase in volume was found in mixtures containing equal proportions of cyclohexane and benzene and up to 20 weight % n -heptane. The magnitude of the effect was reduced by an increase in temperature. It was found that the experimental results could be represented satisfactorily by equations based on the theory of regular solutions. The data are of interest in connection with the manufacture of certain petroleum products that are prepared by the blending of different fractions.