New insight into the reaction mechanism of carbon disulfide hydrolysis and the impact of H2S with density functional modeling

Abstract

The one-step and two-step carbon disulfide hydrolysis reaction mechanisms of CS₂ were investigated in this theoretical work using density functional modeling. The results showed that the association interaction between CS₂ and H₂O results from van der Waals forces. In the first and second steps of two-step hydrolysis, the H atom can easily be captured by the CS, and CO bonds, respectively. Furthermore, the second step (COS hydrolysis) is the controlling step in the two-step CS₂ hydrolysis. During the one-step hydrolysis, the migration of H from H₂O to the H–S bond is easier than that to the CS bond. Meanwhile, the one-step hydrolysis occurs easily without the presence of a catalyst. In addition, the existence of H₂S is not conducive to the CS₂ hydrolysis; however, H₂S is beneficial in maintaining the stability of the intermediates, which results from different interactions such as adsorption and van der Waals forces. The restriction effect for H atom migration caused by H₂S also leads to the increase in the maximum reaction energy barrier. Herein, the detailed reaction mechanisms were investigated using the all-electron density functional theory (DFT) computational method. As such, this study provides a theoretical insight for future application and development.