Catalytic performance of ionic liquid for dehydrochlorination reaction: Excellent activity and unparalled stability

Gas phase catalytic process with the advantages of simply product separation and maximized atom economy, which was a green path used in industrial production. At present, heterogeneous dehydrochlorination catalysts are facing challenge of rapid deactivation caused by released HCl and carbon deposit. In this paper, a series of supported ionic liquid catalysts (SILCs) was synthesized by wet impregnation method and applied to 1, 1, 2-trichloroethane (TCE) dehydrochlorination to produce 1, 1-dichloroethylene (VDC). Tetraarylphosphonium chlorine was the active component with the unique acid resistance and the ability to dissolve coke, which determined the activity and stability of the catalyst. For 6%Tetraphenylphosphonium chloride (TPPC)/SiO2(260 °C, WHSV = 0.19 h−1), the conversion of 1, 1, 2-TCE was ＞99.5%, selectivity of VDC was 86%, and the catalytic activity remained stable within 1100 h. Herein, highly activity for dehydrochlorination was attributed to the strong hydrogen-bond basicity of Cl-, which was decided largely by the interaction between anion and cation of ionic liquid. The reaction mechanism was investigated using FTIR, XPS, TGA-MS, XRF, DFT calculation and two step elimination model induced by alkaline active center is proposed. Such catalysts provide a viable industrial solution to gas dehydrochlorination reaction and design of heterogeneous basic catalysts.