Vapor‐liquid equilibria at high pressures: Calculation of critical temperatures, volumes, and pressures of nonpolar mixtures

Abstract

An analysis of c r i t i c o l doto far a large number o f binary mixtures of normal fluids shows that the c r i t i c a l temperature and the c r i t i c a l volume con each be expressed as quodratic functions o f the surface froction. Eoch of these functions requires one adiustable parameter characteristic o f the binary pair; for any family of chemical components, these parameters, upon suitable reduction, follow definite trends.It was shown that the surface fraction gives much better correlation than any other size-weighted variable. F o r the c r i t i c a l pressure, however, no quodrotic function wos adequate. T o calculate c r i t i c a l pressures, the correlations for critical temperature ond c r i t i c a l volume were used i n conjunction with o slightly altered version of the Redlich-Kwong equation.Generolizotions to systems containing more than two components follow without addition01 assumptions. The methods presented i n this paper provide good estimates for c r i t i c a l constonts of multicomponent mixtures. These ore porticularly useful for onolyzing and correlating vapor-liquid equilibria i n the c r i t i c o l region.The critical properties of pure fluids have received much work. The critical properties of mixtures, however, are not attention and as a result of much experimental work, dating known nearly as well, although experimental d a t a are availback nearly 100 years (3, 6 ) , a s well a s semiempirical cor-able for a surprisingly large number of binary mixtures (58).relations (561, i t is now possible to make good estimates Critical properties of mixtures are required in petroleum of the critical temperature, pressure, and volume of most and natural g a s engineering and for rational design of seppure fluids encountered in typical chemical engineering aration equipment and chemical reactors at high pressures.

Critical temperatures and pressures for hydrocarbon mixtures from an equation of state with renormalization-group theory corrections

“…Many studies are concerned with empirical correlations for critical properties [10][11][12][13][14][15][16][17][18][19] and several popular equations of states (EOS) like RK [20], SRK [21], PR [22] and SAFT [23][24][25] have been used to determine critical points. It has been long recognized, however, that although these EOSs can describe fluid properties fairly well far away from the critical point, because they are mean-field based, they cannot yield the correct limiting properties at the critical point.…”

Effect of Mobile Phase Components on the Separation of Polypeptides Using Carbon Dioxide-Based Mobile Phases

“…Polypeptides were dissolved in ethanol containing 50 mM trifluoroacetic acid to a final concentration of 1 -2 mg/mL. Prausnitz manipulation of the Redlich-Kwong equation of state and carbon dioxide densities computed using the NIST database [9,10]). Under these conditions, none of the polypeptides eluted when either trifluoroacetic acid or potassium heptadecafluorooctanesulfonate were used as mobile phase additives.…”

Influence of Modifiers on Supercritical Fluid Chromatography (SFC) and Supercritical Fluid Extraction (SFE), Part I

“…In section of columns under separation together with complex mobile phase also present analytes of different nature (which are present in initial analyzing mixture). Chueh and Prausnitz [21] [22] have modeled CO 2 with mixtures of some of these compounds (including methanol and ethanol) for the estimation of the critical parameters T c and P c . The most complete collection of SCCO 2 solubility data with multiple solutes is presented in "Solubility in Supercritical…”