Vapor phase hydrofluorination of acetylene to vinyl fluoride over La2O3-Al2O3 catalysts

A series of La-doped Al2O3 catalysts were prepared and tested for the vapor phase hydrofluorination of C2H2 to vinyl fluoride (CH2CHF, VF). It was found that the La-doped catalyst gave a stable catalytic performance and a higher selectivity to the desired VF and a lower selectivity to coke deposition compared with the pure Al2O3 catalyst. The enhancement in VF selectivity on the La-doped catalyst was due to the elimination of acidic sites on the Al2O3 surface by the addition of La2O3, evidenced by NH3–TPD results, which could also explain the declined selectivity to coke deposition on the catalyst. Raman result indicated there were two different vibration forms of CH distortion and CC expansion for the coke deposition.

It is found that the La-doped catalyst gives a stable catalytic performance and a higher selectivity to the desired vinyl fluoride (VF) and a lower selectivity to coke deposition compared with the pure Al2O3 catalyst. The enhancement in VF selectivity on the La-doped catalysts is due to the elimination of acidic sites on the Al2O3 surface by the addition of La2O3, evidenced by NH3–TPD results.Figure optionsDownload as PowerPoint slide