Measurement and modelling of urea solubility in supercritical CO2 and CO2+ethanol mixtures

被引：16

作者：

Catchpole, OJ ^{[1
]}

Tallon, SJ ^{[1
]}

Dyer, PJ ^{[1
]}

Lan, JS ^{[1
]}

Jensen, B ^{[1
]}

Rasmussen, OK ^{[1
]}

Grey, JB ^{[1
]}

机构：

[1] Ind Res Ltd, Lower Hutt, New Zealand

来源：

FLUID PHASE EQUILIBRIA | 2005年 / 237卷 / 1-2期

关键词：

urea solubility; supercritical CO2; ethanol; complex formation;

D O I：

10.1016/j.fluid.2005.09.004

中图分类号：

O414.1 [热力学];

学科分类号：

摘要：

The solubility of urea in supercritical CO2 and CO2 + ethanol was measured over the pressure and temperature ranges 100-300 bar and 313-373 K, respectively, and ethanol concentrations of 0-25 mass% (urea free basis). The solubility in CO2 was measured by a once-through packed bed gravimetric method at a laboratory and pilot scale. The solubility in CO2 + ethanol was measured using two different methods: antisolvent precipitation and a gravimetric packed bed method. The solubility of urea in pure CO2 is very low, ranging from 1.1 x 10(-6) mol fraction at 100 bar, 333 K to 3.1 X 10(-5) at 300 bar, 353 K. The solubility increases exponentially with a linear increase in ethanol content. The highest solubility measured was similar to 1 x 10(-6) mol fraction at 333 K, 150 bar and 26% ethanol. At high ethanol contents, the solubility was almost independent of pressure at a fixed temperature. The solubility was correlated by the Peng-Robinson equation of state with standard mixing rules for the repulsive and attractive parameters; and mixing rules that incorporated the formation of a complex between urea and ethanol. The solubility of urea in ethanol, and ethanol in CO2 was also modelled to obtain interaction parameters for the model. It was not possible to find pairs of interaction parameters that modelled both the solubility in pure CO2, and CO2 + ethanol using the standard Peng-Robinson mixing rules. However, the solubility of urea in pure CO2, and CO2 + ethanol, was well modelled using the Peng-Robinson EOS that incorporated complex formation between urea and ethanol. Assuming an ethanol/urea complex stoichiometry of 2:1 gave a good fit between model predictions and experimental results. (c) 2005 Elsevier B.V. All rights reserved.

引用

页码：212 / 218

页数：7

共 16 条

[1] Phase equilibrium of ethanol plus CO2 and acetone plus CO2 at elevated pressures [J].