Molecular Dynamics Simulation of H2S Solubility in Protic Ionic Liquids

Amine solvent commonly used to remove H2S especially in oil and gas industries. However, amine solvent has major drawbacks such as, high flammability, high volatility, and less efficiency in capturing H2S. Hence, understanding the behaviour of molecules at molecular level and solubility of H2S in protic ionic liquids (PILs) becomes the fundamental interest. In this work, molecular dynamics (MD) simulation with an aid of Bennet Acceptance Ratio (BAR) method was employed to unravel the key factors of the H2S solubility in three PILs namely 2MAES, 2PAES, and 2BAES. The predicted solvation free energy of H2S in these PILs and water showed negative value with the lowest value obtained by 2BAES with �G of �19.42 kJ mol�1. This indicated that H2S was highly soluble in 2BAES compared to the other two PILs, having a value of �12.74 kJ mol�1 and �17.73 kJ mol�1 for 2MAES and 2PAES, respectively. To support the understanding, radial distribution function (RDF) and self-diffusion coefficient (D) were calculated. From these analyses, increasing the mobility of cation�anion resulted in an increase the H2S solubility. © 2021, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.