Measurement of phase equilibrium characteristics and optimization of equations of state of hydrogen-containing CO2 systems

The production processes in the energy-intensive refining and chemical industries produce a large amount of carbon emissions. These emissions often contain a high proportion of hydrogen. The presence of impurities has been demonstrated to affect the phase equilibrium properties of CO2. Furthermore, inappropriate equations of state have been shown to be incapable of accurately predicting the phase characteristics of CO2, thereby potentially compromising the implementation of carbon capture, utilization, and storage technology. Experimental equipment developed for measuring the phase characteristics of impurity-containing CO2 systems is based on the principle of measuring the difference in compressibility between gases and liquids. In this study, the bubble point and dew point pressures of the H2–CO2 binary system and the H2–N2–CO2 multivariate system are measured. The experimental results are compared with those from the PR, GEREG-2008, BWRS, SRK, and PRSV equations, and the errors in the results on bubble point pressure and dew point pressure from each equation are analyzed. It is found that each equation exhibits a different prediction accuracy for hydrogen-containing CO2 systems. For pure CO2, the PR equation is appropriate below 0 °C and the PRSV equation above 0 °C. For the 96%CO2 + 4% H2 binary system, in the range of −30 to 20 °C, the PRSV and SRK equations exhibit obvious deviations in their predictions of bubble point pressure, and the GERG-2008 equation is instead recommended. For the 96%CO2 + 2%H2 + 2%N2 multicomponent system, the PR and GERG2008 equations are recommended in the range of −30 to 20 °C.