High-temperature solubility and thermodynamic correlation of CO2, H2, and CH4 in 1-Ethyl-2-pyrrolidone: Implications for catalytic CO2 hydrogenation to ethanol

The solubilities of CO 2 , H 2 , and CH 4 in 1-ethyl-2-pyrrolidone (NEP) were measured using the isochoric saturation method at 413.15–453.15 K under pressures of 0.45–3.89 MPa (CO 2 ), 4.42–7.64 MPa (H 2 ), and 0.59–3.49 MPa (CH 4 ). The reliability of the apparatus was verified by measuring CO 2 solubility in N-methyl-2-pyrrolidone (NMP) at 323.15–353.15 K. The solubility order in NEP was found to be CO 2 > CH 4 > H 2 . Temperature-dependent Henry’s constants were obtained, and the experimental data were correlated using the Krichevsky–Kasarnovsky equation and the generic Redlich–Kwong (RK) cubic equation of state, with the RK model providing better accuracy. These results offer essential thermodynamic data for describing gas–liquid equilibrium in NEP and support solvent selection and process design in high-temperature CO 2 conversion systems.