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

• Published in: Applied catalysis. B, Environmental Environmental, 2019-10, Vol.255, p.117757, Article 117757
• Main Authors: Zhang, Pengze, Jiang, Zhaobin, Cui, Yanhong, Xie, Guanqun, Jin, Yangzhen, Guo, Lingling, Xu, Yiqi, Zhang, Qunfeng, Li, Xiaonian
• Format: Article
• Language: English
• Subjects: Acid resistance; Atom economy; Basicity; Catalysis; Catalysts; Catalytic activity; Chemical synthesis; Chlorides; Chlorine; Deactivation; Dehydrochlorination; Eliminate reaction; Gas-phase dehydrochlorination; Heterogeneous catalysis; Industrial production; Ionic liquid; Ionic liquids; Ions; Reaction mechanisms; Selectivity; Silicon dioxide; Stability; Tetraphenylphosphonium; Trichloroethane; Vapor phases; Vinylidene chloride
• ISSN: 0926-3373; 1873-3883
• DOI: 10.1016/j.apcatb.2019.117757

Supported ionic liquids catalyst with immobilizing tetraphenylphosphonium chloride on silica surface, which applied for gas phase dehydrochlorination (TCE) of 1, 1, 2-Trichloroethane. The conversion of 1, 1, 2-TCE was>99.9%, selectivity of vinylidene chloride (VDC) was 86% and changed slightly during 1100 h. [Display omitted] •The influence of anion-cation interaction on catalysis activity was investigated.•The anion of ionic liquid play vital important role in gas phase dehydrochlorination reaction.•Signal ionic liquid layer in favor of high Catalytic activity.•Supported ionic liquid catalyst can resolve challenges of acidosis and coke.•Supported ionic liquids catalyst provide an strategy for the design and synthesis of acid-resistant solid base catalyst. 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.