The Catalytic Mechanism of [Bmim]Cl-Transition Metal Catalysts for Hydrochlorination of Acetylene

Ionic liquids (ILs) are green solvents involved in chemical reaction and separation processes. In this paper, four ILs-based metal catalysts were prepared by dissolving four transition metal chlorides into 1-butyl-3-methylimidazolium chloride ([Bmim]Cl). Their catalytic performance was measured, and the catalytic mechanism was studied via density functional theory (DFT) based on the analysis of the Mayer bonding order, Mulliken charge, molecular electrostatic potential (ESP), electron localization function (ELF), and partial density of states (PDOS). The results show that the catalytic activity follows the order [Bmim]Cl-RuCl3 > [Bmim]Cl-AgCl > [Bmim]Cl-CuCl2 > [Bmim]Cl-CuCl. [Bmim]Cl helps to dissolve and activate HCl, and the metal chlorides can greatly reduce the activation energy of the reaction. This study provides new insights into the catalytic mechanism of IL, transition metals, and their synergistic effect from a microscopic point of view and sheds light on the development of new catalysts for acetylene hydrochlorination.