Synthesis of 2,3,3,3-tetrafluoropropene via vapor-phase catalytic fluorination in the presence of Cr-based catalyst

Catalytic impact of Cr-based catalysts obtained by various oxidative treatment was studied for the synthesis of 2,3,3,3-tetrafluoropropene. The Cr-based catalysts were prepared by precipitation, reacted with vapor-phase anhydrous hydrogen fluoride (AHF), and finally treated by various oxidizing agents, such as chlorine and oxygen. The catalysts were characterized using the Brunauer, Emmett and Teller method, X-ray diffraction, scanning electron microscopy and NH₃-temperature programed desorption and were applied to the preparation of 2,3,3,3-tetrafluoropropene (HFO-1234yf) from 2-chloro-3,3,3-trifluoropropene (HCFO-1233xf) via vapor-phase catalytic fluorination. In the HFO-1234yf preparation reaction, the catalyst treated by Cl₂ or O₂ exhibited much higher catalytic activity than did the common Cr-based catalyst due to the larger specific surface area and stronger surface acidity displayed by the oxidized catalysts.