Validation of synthetic method for phase equilibria measurements: Re-examination of CO₂ + methylcyclopentane, CO₂ + 2,2-dimethylbutane, and benchmarking with CO₂ + toluene

Recent publications have reported phase equilibrium data for CO₂ + methylcyclopentane (MCP) and CO 2 + 2,2-dimethylbutane using static-analytical sampling methods that are inconsistent with previously published synthetic-method data. To verify the reliability of our earlier measurements, we have repeated vapor–liquid equilibrium (VLE) experiments for both CO₂ + MCP and CO₂ + 2,2-dimethylbutane in the range 20–90°C using a high-pressure variable-volume PVT cell with visual observation. Our new data agree within 1–2 bar with the values previously reported by our group, confirming the reproducibility of the synthetic method. To further validate our methodology, we also investigated the CO₂ + toluene system, which has been extensively studied in the literature. Our experimental results are in agreement with reference data, thereby confirming the accuracy of the synthetic technique and of the procedures used for mixture preparation and bubble-point detection. These results support the conclusion that the discrepancies between our data and those obtained by static-analytical methods cannot be attributed to errors inherent to the synthetic technique.