Critical Properties of Carbon Dioxide + Methanol, + Ethanol, + 1-Propanol, and + 1-Butanol

Abstract

Critical properties for carbon dioxide + methanol, + ethanol, + 1-propanol, and + 1-butanol were measured using a variable-volume view cell apparatus. Binary mixtures with carbon dioxide mole fractions of 0.976 to 0.637 have been investigated up to 430 K and 175 bar. The dew point and bubble point of the mixtures were measured, particularly in the vicinity of the critical point, in narrow increments in the P-T projection, and the critical point was estimated using two adjacent dew and bubble points. The experimental results were compared with the literature values.

Detecting phase transitions in supercritical mixtures: an enabling tool for greener chemical reactions

“…a reaction, or for particle formation, then the most efficient way to measure the phase behaviour would be to do so in situ so that no additional time would be required to determine the phase behaviour. Furthermore, if one can make the detection method objective, it the insert shows the phase envelope measured by the pressure drop method (triangle) and the data reported in the literature (square) by using conventional visual techniques (Yeo et al 2000). (b) variation of pressure drop with temperature for CO 2 + THF mixtures with increasing CO 2 mole fraction expressed as a percentage, adapted from Akien et al (2010) with permission from the American Chemical Society.…”

ObtainingAntioxidants from Botanic Matrices Applying Novel Extraction Techniques

“…On the other hand, the crit ical temperature and pressure change when cosolvent is added depending on its fraction in the mixtu re. As an examp le, for the system CO 2 + ethanol the critical point moves fro m 310.6 K and 7.77 MPa for 0.0044 mo l% ethanol to 410.3 K and 15.17 MPa for 0.403 mol% ethanol [134]. The temperatures above 330 K are not recommended for processing thermo sensitive compounds, the existence of two phases inside the extractor is co mmon when using high fractions of cosolvent.…”

Sensing the Critical Point of High‐Pressure Mixtures

“…As expected, for each temperature the two sensors agree within experimental error on the pressure at which phase separation occurs and the data agree well with literature values. [11] The traces recorded by both sensors at higher temperatures display the Figure 1. Shear-mode sensor responses (j Z j min ) as a function of pressure along two isotherms showing the difference in the discontinuity caused by phase transitions on a) the bubble point and b) the dew point.…”

“…For the first study, CO 2 + MeOH, both sensors were mounted simultaneously in the same cell. CO 2 + MeOH is an extremely well studied mixture, [10][11][12][13][14] particularly because of the widespread use of MeOH as a cosolvent to enhance the rather low solvent power of pure CO 2 . Even so, there are considerable differences in the value of T c reported by different studies on mixtures of apparently similar composition.…”

“…Even so, there are considerable differences in the value of T c reported by different studies on mixtures of apparently similar composition. [10][11][12][13][14] Figures 2 a and b show the traces recorded from the two sensors over the section of the phase boundary, which includes the critical point. As expected, for each temperature the two sensors agree within experimental error on the pressure at which phase separation occurs and the data agree well with literature values.…”