Abstract
Accurate thermodynamic data for CO2 mixtures containing light gas components are essential for the safe and efficient design of CO2 liquefaction and transport processes in carbon capture, utilization, and storage (CCUS) applications. This study presents an experimental investigation of CO2 mixtures containing light gas components (N2, CH4, H2, and Ar) under conditions relevant to liquefaction and ship transport (−50 °C and −30 °C, 7–20 bar). Vapor–liquid equilibrium (VLE) measurements demonstrated pronounced vapor enrichment of light gas components across all binary and ternary mixtures, with hydrogen exhibiting the lowest solubility and the greatest influence on phase behavior. Obtained experimental data were compared with the predicted results from thermodynamic models, among which GERG-2008 and CPA equation of state showed the best agreement, yielding average absolute deviations below 0.9 mol%. In parallel, cryogenic transfer experiments were conducted to simulate liquefied CO2 (LCO2) transfer between pressurized tanks. Stable transfer was achieved under pressure gradient between tanks, with transient variations in temperature. Vapor compositions were measured before and after the LCO2 transfer to assess compositional changes, while the total transferred LCO2 volume was quantified. Hydrogen showed the most distinct vapor enrichment and temperature drops below −51 °C, suggesting the potential risk of dry ice formation under large-scale operation. These findings provide experimental validation of thermodynamic models and reveal phase behavior of CO2 mixtures in liquefaction and transfer process, forming a robust foundation for LCO2 transport system design.