Synergistic catalysis of chloroalkane dehydrochlorination with acetylene hydrochlorination by immobilized ionic liquid–metal ion co-catalysts: a DFT study

Abstract

Pronounced adsorption of HCl critically hinders the catalytic dehydrochlorination of halogenated hydrocarbons, leading to catalyst degradation or deactivation. Coupling this process with HCl-consuming acetylene hydrochlorination offers an effective strategy to mitigate this issue. Density functional theory (DFT) simulations at the PBE0/ma-TZVP level are employed to investigate the adsorption of reactants on a series of metal chlorides and their Cl⁻ complexes. Based on the adsorption energy data, a variety of co-catalysts with different characteristics are screened and their catalytic mechanisms are systematically investigated. The KCl–CuCl–ionic liquid catalyst has been theoretically proven to be the optimal catalyst, facilitating the dehydrochlorination of chloroalkanes (ΔG = 134.0 kJ mol⁻¹) and acetylene hydrochlorination (ΔG = 124.4 kJ mol⁻¹) through the different dissociation states of ionic liquids and metal salts. Furthermore, KCl inhibits multiple acetylene adsorption, accelerates olefin desorption, and hinders the formation of copper acetylide, thereby ensuring sustained catalytic stability.