Carbon-Interacted AlF₃ Clusters as Robust Catalyst for Dehydrofluorination Reaction with Enhanced Undercoordination and Stability

Abstract

Conversion of potent greenhouse gases, hydrofluorocarbons (HFCs), to value-added hydrofluoroolefins (HFOs) is of great importance. AlF 3 catalysts play a major role in this process. Formation and maintenance under coordinated Al are the key to prepare efficient catalysts. Herein, carbon interacted AlF 3 nanoclusters catalyst (AlF 3 −SAPO-5) was effectively achieved with SAPO-5 molecular sieves as precursors via pyrolysis followed by in situ fluorination. This process results in a strong interaction between the carbonaceous material and active aluminum (Al) species. The results show that AlF 3 −SAPO-5 possesses both high activity and thermal stability. For 1,1-difluoroethane (HFC-152a) dehydrofluorination, the conversion can reach up to 95% at a reaction temperature of 350 °C. The reaction rate is almost 4 times higher than that of AlF 3 prepared by traditional pyrolysis (AlF 3 -py). It implies that the confinement effect contributes to the formation of AlF 3 nanoclusters with abundant 4-and 5-coordinated Al species stabilized by the F−Al−O−C structure. In addition, the carbon-interacted AlF 3 nanoclusters exhibit superb sintering resistance. Given its fantastic activity and thermal stability, the carbon-interacted AlF 3 nanoclusters show great potential for the catalytic dehydrofluorination of fluorinated alkanes.