3762-48-9Relevant academic research and scientific papers
Catalytic Gas-phase Fluorination of Hexachlorobutadiene to 1,2-Dichlorotetrafluorocyclobutene over Cr/Zn-based Catalysts
He, Jinwei,Zhang, Mengxue,Zhou, Biao,Zhou, Xiaomeng
, p. 760 - 770 (2018)
In this paper, the gas-phase fluorination of hexachlorobutadiene (HCBD) to synthesize 1,2-dichlorotetrafluorocyclobutene (DTB) was carried out over a series of Cr/M/Zn catalysts (M = Ni, Co, Cu, In, Al). The influence of prefluorination by different fluorinating agents (HF, 95%HF + 5%Cl2, 95%HF + 5%O2, CF2O, CF2Cl2) on catalytic performance of Cr/Co/Zn sample was also investigated. The addition of prompters to the Cr/Zn catalyst improved remarkably its catalytic properties. The Cr/Ni/Zn catalyst exhibited the best catalytic activity (1.318 mmol/h/g) at 390 °C and the Cr/Co/Zn catalyst showed the best DTB selectivity (42.5%) at 350 °C. Compared to that of gaseous HF, the catalytic performance of the Cr/Co/Zn catalyst after treatment by HF + O2 and CF2O increased considerably, whereas for HF + Cl2 and CF2Cl2 it showed little effect. In order to identify the different species (Cr─O, Cr─F, CrOxFy) present on catalysts’ surface and determine their exact role, these catalysts before and after the reaction were characterized by X-ray photoelectron spectroscopy. It was found that the concentration of the various species was responsible for the activity and lifetime of catalysts. Moreover, a possible reaction route is proposed based upon the product distribution. The most feasible formation pathway of DTB proceeded via the cyclization of C4Cl4F2 or C4Cl3F3 to yield c-C4Cl4F2 and c-C4Cl3F3 followed by further the Cl/F exchange.
