Vapor-Liquid Equilibria at High Pressures for the Mixtures of Carbon Dioxide, Alcohols and Esters
Date Issued
2006
Date
2006
Author(s)
Cheng, Chen-Hsi
DOI
zh-TW
Abstract
The application of supercritical fluids (SCF) as an alternative solvent in industrial processes has attracted more and more attention in recent years. The key points for the design of process and selection of optimal operating condition are the equilibrium solubility data in supercritical fluids and appropriate thermodynamic models for calculation.
A static type with visual windows apparatus was used to measure the vapor-liquid equilibria (VLE) of CO2 with isopropyl acetate, diethyl carbonate, ethyl butyrate binary mixtures at 308.15 to 318.15 K over the pressure range from 3.1 to 8.9 MPa. New VLE data for CO2 with esters are presented. These VLE data were also correlated using the Soave-Redlich-Kwong and the Peng-Robinson equations of state with various mixing rules. It is shown that both equations of state with the van der Waals mixing rules and two adjustable parameters gave satisfactory correlation results.
The apparatus was also used to measure the VLE of CO2 with ethanol - ethyl acetate, 1-propanol - propyl acetate ternary mixtures, and ethanol - 1-propanol - ethyl acetate quaternary mixture at 303.15 to 318.15 K over the pressure range from 4.0 to 10.0 MPa. New VLE data for CO2 with mixed solvents are presented. It was observed that, at specific temperature and pressure, ethanol or 1-propanol can be separated from mixed solvent into the vapor phase at all concentrations in the presence of high pressure CO2. These ternary VLE data were also correlated and predicted using the modified Soave-Redlich-Kwong (MSRK) and the Peng-Robinson (PR) equations of state with mixing rule or liquid model. The PR equation of state by the Huron-Vidal mixing rule with the NRTL activity coefficient model gave satisfactory correlation and prediction results.
Calculation of liquid solubility in supercritical fluids is very important for design purpose. In this research, correlation and prediction for the VLE of CO2 with alcohol - water ternary systems at high pressures were discussed. It is useful for the cleaning and the removal of water in the semiconductor industry for wafer production. At the same condition of temperature and pressure, ethanol showed the best effect for water removal. The ratio of the co-solvent residual to water removal is minimum at T = 318.15 K and P = 20.0 MPa. These results and discussion provide the information of cleaning and drying processes using supercritical fluid.
Subjects
汽液相平衡
雙成分
三成分
四成分
二氧化碳
醇類與酯類混合物
VLE
binary
ternary
quaternary
high pressure
carbon dioxide
alcohol and ester mixture
Type
thesis