Screening Physical Solvents for Methyl Mercaptan Absorption Using Quantum Chemical Calculation Coupled with Experiments

This work presents a screening method of physical solvents for methyl mercaptan (MeSH) absorption using quantum chemical calculations. The absorption solubility and thermodynamic behaviors of dimethyl sulfoxide (DMSO), sulfolane (SUL), propylene carbonate (PC), N,N-dimethylformamide (DMF), and 1-methyl-2-pyrrolidinone (NMP) for MeSH were calculated and analyzed using the COSMO-RS model, and the absorption mechanism was probed combining the quantum theory of atoms in molecules (QTAIM) and reduced density gradient (RDG). Results show that the absorption solubility of the five solvents for MeSH by COSMO-RS model calculations follow the order of NMP > PC > DMSO > SUL > DMF, and the van der Waals forces and hydrogen bond forces determine the absorption solubility of physical solvents for MeSH. In addition, the experimental results of MeSH Henry coefficients in the above five solvents follow the same order as the calculated results. However, the calculated Henry coefficients’ value largely deviates from the experimental value; therefore, we believe that this calculation method is only available for qualitative screening. This work provided a feasible approach to screening high-performance physical solvents for MeSH removal.