Solubilities of CO2, CH4, C2H6, CO, H2, N2, N2O, and H2S in commercial physical solvents from Monte Carlo simulations

The removal of acid gas impurities from synthesis gas or natural gas can be achieved using several physical solvents. Examples of solvents applied on a commercial scale include methanol (Rectisol), poly(ethylene glycol) dimethyl ethers (Selexol), n-methyl-2-pyrrolidone (Purisol), and propylene carbonate (Fluor solvent). Continuous Fractional Component Monte Carlo (CFCMC) simulations in the osmotic ensemble were used to compute the Henry coefficients of the pure gases CO2, CH4, C2H6, CO, H-2, N-2, N2O, and H2S in the aforementioned solvents. The predicted Henry coefficients are in good agreement with the experimental results. The Monte Carlo method correctly predicts the gas solubility trend in these physical solvents, which obeys the following order: H2S > CO2 > C2H6 > CH4 > CO > N-2 > H-2. The gas separation selectivities for the precombustion process and the natural gas sweetening process are calculated from the pure gas Henry coefficients. The CO2/N2O analogy is verified for the solubility in these solvents.

Automated summary

Several physical solvents, such as methanol, poly(ethylene glycol) dimethyl ethers, n-methyl-2-pyrrolidone, and propylene carbonate, can be used for the removal of acid gas impurities from synthesis gas or natural gas. Monte Carlo simulations in the osmotic ensemble accurately predict the gas solubility trend in these solvents, and the predicted Henry coefficients are in good agreement with experimental results. The solubility of gases in these solvents follows the order: H2S > CO2 > C2H6 > CH4 > CO > N-2 > H-2.