Catalytic gas-phase fluorination of 1,1,2,3-tetrachloropropene to 2-chloro-3,3,3-trifluoropropene over the fluorinated Cr sub(2)O sub(3)-based catalysts

Gas-phase fluorination of 1,1,2,3-tetrachloropropene to 2-chloro-3,3,3-trifluoropropene (HCFO-1233xf) was investigated over the fluorinated Cr sub(2)O sub(3) catalysts with and without promoters. The reaction conditions showed significantly effects on product distribution including temperature, molar ratio of reactants and contact time. The selectivity to HCFO-1233xf was favored under relative higher temperature, larger HF/1,1,2,3-tetrachloropropene ratio and shorter contact time. Based on the data of product distribution over the fluorinated Cr sub(2)O sub(3) catalyst, a possible reaction path involving complicated consecutive steps was proposed including the addition/elimination and the direct CI/F exchange. The XRD, XPS and Raman results indicated that introducing Mg, Ca and La onto Cr sub(2)O sub(3) promoted the formation of highly dispersed CrO sub(x)F sub(y) species during the pre-fluorination process, whereas the presence of Y inhibited the formation of CrO sub(x)F sub(y). The BET results showed that the addition of La and Y into Cr sub(2)O sub(3) enhanced the surface area of fluorinated samples. The fluorinated Cr sub(2)O sub(3) promoted by La (La/F-Cr sub(2)O sub(3)) catalyst displayed the best activity and lifetime among the prepared catalysts, which can be attributed to its rich CrO sub(x)F sub(y) species and high surface area.