Facile Preparation of BaCl_xF_y for the Catalytic Dehydrochlorination of 1-Chloro-1,1-Difluoroethane to Vinylidene Fluoride

• Main Authors: Wei Yu, Wenfeng Han, Yongnan Liu, Jiaqin Lu, Hong Yang, Bing Liu, Haodong Tang, Aimin Chen, Ying Li
• Format: Article
• Language: English
• Published: MDPI AG 2020-04-01
• Series: Catalysts
• Subjects: barium chlorofluoride; catalytic pyrolysis; barium fluoride; dehydrochlorination; 1-chloro-1,1-difluoroethane; vinylidene fluoride
• Online Access: https://www.mdpi.com/2073-4344/10/4/377

BaCl_xF_y as well as BaF₂ and BaClF catalysts were prepared by solid-state reaction at room temperature with Ba(OH)₂ as the precursor and NH₄F/NH₄Cl as the F and Cl sources. The catalysts were applied for the dehydrochlorination of 1-chloro-1,1-difluoroethane to vinylidene fluoride at 350 °C. The industrial manufacture of vinylidene fluoride (VDF) is carried out at 600–700 °C, whereas the BaCl_xF_y catalysts provided a promising pathway to produce VDF at much lower temperatures. Unfortunately, the selectivity of VDF over BaF₂ decreased from 94% to 84% along with the deactivation of the BaF₂ catalyst monotonically. In the presence of small amounts of Cl in BaF₂, stabilized selectivity was achieved. Over BaCl_0.05F_0.95, BaCl_0.1F_0.9 and BaCl_0.25F_0.75, no decrease in VDF selectivity was observed. Clearly, the presence of small amounts Cl during solid-state preparation inhibited the growth of BaF₂ crystalline significantly. Far smaller particles were achieved. The particle size, or more precisely, the crystal size of the barium catalyst played a major role in the catalytic performance. In addition to the crystal growth, the presence of small amounts of Cl during catalyst preparation changed the chemical state of Ba, and therefore the adsorption and activation of the C–Cl bond for HCFC-142b were altered.