Hydrolysis of HFC-134a using a red mud catalyst to reuse an industrial waste

Abstract

Red mud obtained from industrial waste generated during the Bayer process was evaluated as a catalyst for the decomposition of hydrofluorocarbon-134a (HFC-134a), a greenhouse gas. The durability of the catalyst was evaluated through continuous operation for 66 h at 650 °C. The conversion of HFC-134a increased concurrently during the stability test, reaching ∼ 99 % after 50 h. After long-term testing, HFC-134a conversion over the red mud catalyst was evaluated as a function of temperature; an increase in the catalytic activity was observed over all temperature ranges. X-ray diffraction analysis revealed that tricalcium aluminate and gehlenite were formed during the long-term test, and the increase in the catalytic activity of the red mud could be attributed to the formation of a crystalline structure. Scanning electron microscopy/energy-disperse X-ray spectroscopy analysis confirmed that AlF3 and carbon were not generated during the durability tests with high HFC-134a decomposition yield. Based on the HFC-134a decomposition tests and catalyst analysis, we conclude that the red mud catalyst has good catalytic activity and durability when used in HFC-134a decomposition.