Enhanced Solubility of Hydrogen in CO2-Expanded Liquids

Vapor−liquid equilibrium (VLE) data for the systems CO2/H2/acetonitrile, CO2/H2/acetone, and CO2/H2/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 H2 in expanded solvents was improved by the presence of CO2 but not significantly; the solubility is less than one can achieve with pure H2 at the same total pressure. Nevertheless, CO2 does improve H2 solubility in all three solvents at the conditions studied, even though the H2 solubility enhancement by CO2 is very modest. The Peng−Robinson equation of state predicted the ternary VLE remarkably well using only binary interaction parameters.