Catalytic performance of alumina catalysts with different surface properties for the dehydrofluorination of HFC-134a (1,1,1,2-Tetrafluoroethane)

The activated alumina with different specific surface areas and different acidity was used to catalyze the dehydrofluorination reaction of CF 3 CH 2 F (HFC-134a). The catalytic performance of the alumina catalysts was rationalized by analyzing the relationship between specific surface area and acidity before and after fluorination. A series of physiochemical techniques, including Scanning Electron Microscope (SEM), X-ray diffraction (XRD), and N 2 physical adsorption (BET), were used to investigate the changes in catalyst structure and surface morphology before and after being tested for the dehydrofluorination reaction. The Al 2 O 3 catalyst prepared from the precipitation method (Al 2 O 3 -P) demonstrated the best stability among all the Al 2 O 3 catalysts. Results from XRD techniques showed that Al 2 O 3 catalysts were fully or partially fluorinated into AlF 3 after the dehydrofluorination reaction. Al 2 O 3 -B catalyst and Al 2 O 3 -S catalyst containing mainly α-AlF 3 deactivate easier than the Al 2 O 3 -P catalyst, which has primarily β-AlF 3 . In addition, it can be concluded the high surface area Al 2 O 3 -P catalyst still has the highest specific surface area and pore size when fluorinated to AlF 3 , while forming the β-AlF 3 crystalline phase. Therefore, it has the optimum catalytic performance for dehydrofluorination of HFC-134a. This provides a new idea for designing alumina catalysts with reasonable structure.