Dehydrofluorination of 1, 1, 1, 3, 3-pentafluoropropane over C-AlF3 composite catalysts: Improved catalyst stability by the presence of pre-deposited carbon

Abstract A series of C-AlF 3 composite catalysts were prepared using a sol-gel method and different aluminum precursors (i.e. aluminum isopropoxide (Al(O i Pr) 3 ) and aluminum diacetate hydroxide (C 4 H 7 AlO 5 )). These catalysts were very active in gas-phase dehydrofluorination of 1, 1, 1, 3, 3-pentafluoropane. For example, a catalyst calcined at 400 °C with aluminum isopropoxide as the precursor (denoted as C-AlF 3 -AIP-400) gave a reaction rate of 8.30 μmol s −1 g cat -1 and a selectivity to 1, 3, 3, 3-tetrafluoropropene (HFO-1234ze) of above 99% at 340 °C. More importantly, the C-AlF 3 catalysts showed excellent stability during 100 h reaction, while the pure AlF 3 catalyst suffered severe deactivation owing to the coke deposition on the surface. In contrast, pre-deposited carbonaceous species formed in the catalyst due to the incomplete decomposition of organic precursors during the preparation procedure, which blocked strong acidic sites in the AlF 3 and thus maintained the catalyst stability. Therefore, these findings provide useful information on the development of efficient catalyst for this reaction, particularly on the maintainance of catalyst stability.