Solvents azeotropic data

Even though the simple distillation process has no practical use as a method for separating mixtures, simple distillation residue curve maps have extremely usehil appHcations. These maps can be used to test the consistency of experimental azeotropic data (16,17,19) to predict the order and content of the cuts in batch distillation (20—22) and, in continuous distillation, to determine whether a given mixture is separable by distillation, identify feasible entrainers/solvents, predict the attainable product compositions, quaHtatively predict the composition profile shape, and synthesize the corresponding distillation sequences (16,23—30). By identifying the limited separations achievable by distillation, residue curve maps are also usehil in synthesizing separation sequences combining distillation with other methods. 

The recovery process must also be kept in mind, and fundamental vapor liquid data, such as the formation of azeotropes, should be examined. Azeotropic data can be found in the literature [1], but are sometimes contradictory. Finally, solvents that are unstable, toxic, expensive, and high grade should be avoided, unless the product price is high and the feed flow rate is low. 

Data of Azeotropes. The choice of azeotropic entrainer for a desired separation is much more restricted than that of solvents for extractive distillation, although many azeotropic data are known. The most extensive compilation is that of Ogorodnikov, Lesteva, and Kogan (Handbook of Azeotropic Mixtures (in Russian), 1971). It contains data of 21,069 systems, of which 1274 are ternary, 60 multicomponent, and the rest binary. Another compilation Handbook of Chemistry and Physics, 60th ed., CRC Press, Boca Raton, FL, 1979) has data of 685 binary and 119 ternary azeotropes. Shorter lists with grouping according to the major substances also are available in Lange s Handbook of Chemistry... 

In distilling mixed solvents it is generally necessary to consult azeotrope data books6 for mixture compositions. Chemists generally prefer to carry out reactions in reiativeiy low-boiling low-cost solvents. Most of the common solvents are listed in Table 1, with a few notes on issues. 

In this book binary azeotropes mostly drawn from Horsley s Azeotropic Data are listed. There are a great number of possible ternary or more complex mixtures of solvents that are used, and some ternary azeotropes have been recorded. It is extremely rare for a ternary azeotrope to occur if all three binary mixtures which its components can form are not also azeotropic. 

While all volumes in this series, Azeotropic Data, are collections of data, mostly from the literature, the supplement that was published as No. 35 in the Advances in Chemistry Series included previously unpublished data from industrial files, of which most was from Union Carbide Chemicals Co., assembled by William S. Tamplin. Additional contributions came from Commercial Solvents Corp., Eastman Chemical Products, Inc., Farbenwerke Hoechst, Imperial Chemical Industries Ltd., and Minnesota Mining and Manufacturing Co. These data are continued in the present volume. 

Azeotropic Data III compiled Lee H. Horsley and published by the American Chemical Society in 1973. This is a very large collection of binary and ternary or more complex mixtures of solvents indicating whether or not azeotropes exist. 

In Section 11.4, it was shown how suitable solvents can be selected with the help of powerful predictive thermodynamic models or direct access to the DDB using a sophisticated software package. A similar procedure for the selection of suitable solvents was also realized for other separation processes, such as physical absorption, extraction, solution crystallization, supercritical extraction, and so on. In the case of absorption processes or supercritical extraction instead of a g -model, for example, modified UNIFAC, of course an equation of state such as PSRK or VTPR has to be used. For the separation processes mentioned above instead of azeotropic data or activity coefficients at infinite dilution, now gas solubility data, liquid-liquid equilibrium data, distribution coefficients, solid-liquid equilibrium data or VLE data with supercritical compounds are required and can be accessed from the DDB. 

The 85th Edition includes updates and expansions of several tables, such as Aqueous Solubility of Organic Compounds, Thermal Conductivity of Liquids, and Table of the Isotopes. A new table on Azeotropic Data for Binary Mixtures has been added, as well as tables on Index of Refraction of Inorganic Crystals and Critical Solution Temperatures of Polymer Solutions. In response to user requests, several topics such as Coefficient of Friction and Miscibility of Organic Solvents have been restored to the Handbook. The latest recommended values of the Fundamental Physical Constants, released in December 2003, are included in this edition. Finally, the Appendix on Mathematical Tables has been revised by Dr. Daniel Zwillinger, editor of the CRC Standard Mathematical Tables and Formulae it includes new information on factorials, Clebsch-Gordan coefficients, orthogonal polynomials, statistical formulas, and other topics. 

The physical piopeities of ethyl chloiide aie hsted in Table 1. At 0°C, 100 g ethyl chloride dissolve 0.07 g water and 100 g water dissolve 0.447 g ethyl chloride. The solubihty of water in ethyl chloride increases sharply with temperature to 0.36 g/100 g at 50°C. Ethyl chloride dissolves many organic substances, such as fats, oils, resins, and waxes, and it is also a solvent for sulfur and phosphoms. It is miscible with methyl and ethyl alcohols, diethyl ether, ethyl acetate, methylene chloride, chloroform, carbon tetrachloride, and benzene. Butane, ethyl nitrite, and 2-methylbutane each have been reported to form a binary azeotrope with ethyl chloride, but the accuracy of this data is uncertain (1). 

Recently several patents have been issued (16—18) describing the use of 1,2-dichloroethylene for use in blends of chlorofluorocarbons for solvent vapor cleaning. This art is primarily driven by the need to replace part of the chlorofluorocarbons because of the restriction on their production under the Montreal Protocol of 1987. Test data from the manufacturer show that the cleaning abiUty of these blends exceeds that of the pure chlorofluorocarbons or their azeotropic blends (19). 

Drawing pseudo-binaryjy—x phase diagrams for the mixture to be separated is the easiest way to identify the distillate product component. A pseudo-binary phase diagram is one in which the VLE data for the azeotropic constituents (components 1 and 2) are plotted on a solvent-free basis. When no solvent is present, the pseudo-binaryjy—x diagram is the tme binaryjy—x diagram (Eig. 8a). At the azeotrope, where the VLE curve crosses the 45° line,... 

As can be seen from the data in Table 35.1, the maximum reaction rate is achieved at the 5 2 formic acid triethylamine ratio that is the commonly used azeotropic mixture known as TEAF. When more acid is present, the catalyst may be less active, but equally there may be less formate anion (i.e., the active reagent). The concentration of the latter also depends upon the solvent being used. When there is more triethylamine present the reaction rate also decreases, and there are some indications that triethylamine may deactivate the catalyst. However, the use of formic acid mixtures with ammonia, ethylamine or diethy-lamine is less effective than triethylamine. 

The existence of compositional heterogeneity may be evidenced by the dependence of the measured v on the extent of conversion of monomers to terpolymer for a random terpolymer163) (Fig. 56). Other data on the same diagram demonstrate that composition and v remain sensibly constant with conversion for a partial azeotrope. These observations are corroborated by the LS results in Table 15, which show that for the random terpolymer, M varies between 2.63 x 10s and 4.05 x 10s (that is, by about 50%) according to the solvent used. In contrast, for the partial... 

The azeotrope 70/30 MeCl2/HFIP Is an excellent solvent for PET and similar pol3nners, as well as for polystyrene. This combination, along with Its UV transparency, makes It an excellent GPC solvent. The Du Pont Product Information and Material Safety Data Sheet on HFIP should be consulted before using this system. 

From the equilibrium composition and temperature, it can be deduced that copper(II) chloride and nickel(II) chloride break the azeotrope, while strontium chloride moves it toward a richer ethanol concentration. Figures 3 and 4 show solubility data for these systems, expressed in grams of salt per hundred grams of solvent, plotted against liquid composition in wt % on a salt-free basis. Solubility data for the copper(II) chloride system (see Figure 3) show a maximum... 

Walker et al. [114] examined several methods and solvents for use in the extraction of petroleum hydrocarbons from estuarine water and sediments, during an in situ study of petroleum degradation in sea water. The use of hexane, benzene and chloroform as solvents is discussed and compared, and quantitative and qualitative differences were determined by analysis using low-resolution computerised mass spectrometry. Using these data, and data obtained following the total recovery of petroleum hydrocarbons, it is concluded that benzene or benzene-methanol azeotrope are the most effective solvents. 

This study was undertaken to obtain the necessary vapor-liquid equilibrium data and to determine the distillation requirements for recovering solvent for reuse from the solvent-water mixture obtained from adsorber regeneration. Previous binary vapor-liquid equilibrium data (2, 3) indicated two binary azeotropes (water-THF and water-MEK) and a two phase region (water-MEK). The ternary system was thus expected to be highly nonideal. 

Compilations of infinite-dilution activity coefficients, when available for the solute of interest, may be used to rank candidate solvents. Partition ratios at finite concentrations can be estimated from these data by extrapolation from infinite dilution using a suitable correlation equation such as NRTL [Eq. (15-25)]. Examples of these lands of calculations are given by Walas [Phase EquU ria in Chemical Engineering (Butterworth-Heinemann, 1985)]. Most activity coefficients available in the literature are for small organic molecules and are derived from vapor-liquid equilibrium measurements or azeotropic composition data. 

The recovery of the waste streams was complex, since a series of azeotropes had to be separated. Different alternatives were simulated and initial cost estimates were made by computer simulation alone. The first simulations were based only on the physical properties incorporated in the software data bank. In a second step additional physical properties mostly liquid liquid equilibrium (LLE) data were measured in order to increase the accuracy of the simulation of the most critical steps. First screening experiments of pervaporation to eliminate water and polar impurities such as methanol and ethanol from the tetrahydrofuran (THF) mixtures were stopped early, as it appeared that the alternatives based on counter current extraction (CCE) and rectification alone were less expensive and probably more robust. The most promising processes were piloted. The pilot experiments allowed confirmation of the results of the simulations and allowed the simulations to be updated to reflect the pilot results. A large part of the work during the pilot experiments was to verify the behaviour of further impurities contaminating the solvents, which had not been taken into account in the first screening. All impurity substances had to be purged efficiently, so that they would not accumulate after repeated recoveries of the solvents. 

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