Evolution of Lewis acidity by mechanochemical and fluorination treatment of silicon carbide as novel catalyst for dehydrofluorination reactions

Transforming potent greenhouse gasses, hydrofluorocarbons (HFCs) to hydrofluoroolefins (HFOs) is an environmentally friendly and low energy input route compared with traditional incineration method. During the conversion process, Lewis acidity of the catalysts play a vital role in the activity. Here, inspired by the fluorinated metal oxide, a novel nonmetallic catalyst SiC was fabricated via sequentially mechanochemical treatment and fluorination. With series characterizations, it demonstrated that on the super surface of SiC, there are thin layers of graphite, COOH species, SiO 2 and Si 4 C 4-x O 2 substrates. Through the mechanochemical treatment, the layers of graphite, COOH species and partial SiO 2 could be grinded off. Hence, the exposed SiO 2 residue could be removed via the fluorination by HFC-152a and HF forming volatile SiF 4 . At the same time, the transition layer, Si 4 C 4-x O 2 was fluorinated to Si 4 C 4-x F 2 accompanied with enhanced Lewis acidity. As a result, the activity of the treated SiC was significantly superior than the unmilled SiC. These findings provide a feasible way to develop the catalytic performances of nonmetallic catalysts for the dehydrofluorination.