Carbon-Interacted AlF<sub>3</sub> Clusters as Robust Catalyst for Dehydrofluorination Reaction with Enhanced Undercoordination and Stability
Yiwei Sun, Xiaoli Wei, Wei Zhang, Zhen Wang, Jianhai Jiang, Fangcao Liu, Bing Liu, Wenfeng Han
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.