Enhanced Solubility of Oxygen and Carbon Monoxide in CO2-Expanded Liquids

• Published in: Industrial & engineering chemistry research 2006-07, Vol.45 (15), p.5351-5360
• Main Authors: Lopez-Castillo, Zulema K, Aki, Sudhir N. V. K, Stadtherr, Mark A, Brennecke, Joan F
• Format: Article
• Language: English
• Subjects: Applied sciences; Chemical engineering; Exact sciences and technology
• ISSN: 0888-5885; 1520-5045
• DOI: 10.1021/ie0601091

CO2-expanded liquids are attractive solvent mixtures for many reactions since they have the potential to be designed to dissolve liquid and gaseous reactants, as well as catalysts, can have improved mass transfer compared to traditional liquid-phase reactions, can reduce the amount of volatile organics solvent necessary, and can ameliorate safety concerns. Of primary importance in evaluating CO2-expanded liquids for reactions involving permanent gases is the solubility of those gases in the liquids in the presence of CO2. Here, we report the solubility of O2 and CO in CO2-expanded acetonitrile, acetone, and methanol at temperatures between 25 and 40 °C and pressures to 90 bar. The solubility of O2 and CO in the CO2-expanded liquids is enhanced over the solubility in the absence of CO2 at the same O2 or CO fugacity. However, in no case in the mixed gas system did the O2 or CO solubility substantially exceed what one could achieve with the pure O2 or pure CO at the same total pressure. Thus, the enhancement of the solubility of O2 and CO by CO2 is relatively modest under the conditions investigated. Most importantly, we found that the Peng−Robinson equation of state, using only binary interaction parameters fit to binary data, was quite successful in predicting the phase behavior of the ternary systems.