Enhanced Solubility of Hydrogen in CO2-Expanded Liquids

Vapor−liquid equilibrium (VLE) data for the systems CO 2 /H 2 /acetonitrile, CO 2 /H 2 /acetone, and CO 2 /H 2 /methanol were determined at 40 °C and 25, 60, and 90 bar. A variable volume view cell was used coupled with an online gas chromatograph. The solubility of H 2 in expanded solvents was improved by the presence of CO 2 but not significantly; the solubility is less than one can achieve with pure H 2 at the same total pressure. Nevertheless, CO 2 does improve H 2 solubility in all three solvents at the conditions studied, even though the H 2 solubility enhancement by CO 2 is very modest. The Peng−Robinson equation of state predicted the ternary VLE remarkably well using only binary interaction parameters.