Phase diagrams methanol mixtures

Figure 7.2 A three-dimensional phase diagram for a Type I binary mixture (here, CO2 and methanol). The shaded volume is the two-phase liquid-vapor region. This is shown ti uncated at 25 °C for illustration purposes. The volume surrounding the two-phase region is the continuum of fluid behavior.

J. Zhao and S. V. Olesik, Phase diagram studies of methanol-CHFj and methanol-FI20-CF1F3 mixtures. Fluid Phase Equilib. 154 261-284 (1999). 

Fig. 8.1. Original diagrams of the first COSMO-RS phase-diagram calculations by Iven Clausen [96] for four alcohol-water mixtures (methanol at 60 C, ethanol at 55 °C, 1-propanol at 60 °C and 1-butanol...

Prepare phase diagrams for acetone(l)-methanol(2) mixture using Raoult s law ... 

The phase diagram given in Fig. 21 for darodipine-polyethylene glycol 6000 results from DSC experiments carried out by two techniques. The DSC of physical mixtures obtained by grinding were scanned just after the end of melting. After cooling a second scan at 5Kmin was performed. In the second technique the mixtures were dissolved in methanol and the solvent evaporated. With both techniques, the same results were obtained. 

Fig. 1 Phase diagrams of methanol mixtures with (A) ethyl ether at 115°C and (B) u-pentane at 99.6°C. (From Refs. . ) (View this art in color at WWW. dekker. com.)...

Of particular interest to those in the natural gas industry is the phase diagram of hydrate systems in the presence of inhibitors. Fig. 3 shows the phase diagram for methane hydrates in the presence of methanol and a NaCl and KCl mixture. The solid line is the three-phase equilibrium curve for methane in pure water. As seen from Fig. 3, forming hydrates in the presence of either an alcohol or salt increases the pressure required for gas hydrate formation, at a given temperature. 

Figure 2.4. Phase diagram for methanol in the synthesis of MTBE expressed in terms of transformed compositions (equation 2.18). Remrirks the location of the reactive eizeotrope is tracked down at the intersection of the residue curve and the line X =Y reacting mixtures of various compositions are depicted. System features operating pressure is 11-10 Pa inert nC4 is present in the mixtme.

Carbon dioxide, the most frequently used supercritical solvent, is not a particularly good solvent for polar substances. In order to improve the solubility, a polar second component, such as methanol or ethanol, may be added. The solvent is now a binary mixture, and two phases may be encountered at conditions where carbon dioxide is supercritical (cf. Fig. 7). Expanding use of cosolvents has revealed big gaps in the knowledge of the relevant binary phase diagrams these gaps are now being rapidly filled. 

Fig. 7 Schematic LCST phase diagram of PNIPAM [0.1 wt%] as a function of the composition of the methanol-water solvent mixture. Adapted from Soft Matter , 2010, 1176-1184, figure 1, [125] with permission of The Royal Society of Chemistry...

To illustrate phase separation in liquid mixtures, we consider the phase diagram of methanol-n-hexane, a typical binary liquid (Figure 5.15). Above the critical solution temperature of 34.5 °C, the two liquids mix at all volume ratios. Below 34.5 °C they only mix at low volume ratios of either methanol or hexane. If we go along an... 

Figure 5.15 Phase diagram of a binary mixture of methanol and n-hexane with an upper critical solution temperature of 34.5 °C. Methanol (M) has a higher density than hexane (H) and will therefore form the bottom phase.

Figure Pressure vs. liquid and vapor mole fractions (Pxy) phase diagram for methanol (a)—water (b) binary mixtures at a constant temperature of 323 K. This system shows positive deviations from Raoult s law. The straight line demonstrates what the liquid mole fraction would be in the case of Raoult s law.

Figure 8.5 Vapor vs. liquid mole fractions (xy) phase diagram for methanol (a)-water (b) binary mixtures at a constant pressure of 1 atm. (a) xy diagram with 45° line indicated (b) stages in distillation at total reflux (c) stages in a five tray distillation column with operating lines shown. Stages in distillation are illustrated on the right of (b) and (c).

Figure 3.4 shows the water-methanol mobile phase example of a mixture problem. A three-component mixture that must add up to 100% can be represented on a triangular graph, also called a ternary or trilinear diagram (see figure 3.5). When a system is optimized, it is important to be alert for... 

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