Highly Efficient Decomposition of Perfluorocarbons for over 1000 Hours via Active Site Regeneration.

Abstract

Tetrafluoromethane (CF4), the simplest perfluorocarbon (PFC), has the potential to exacerbate global warming. Catalytic hydrolysis is a viable method to degrade CF4, but fluorine poisoning severely restricts both the catalytic performance and catalyst lifetime. In this study, Ga is introduced to effectively assists the defluorination of poisoned Al active sites, leading to highly efficient CF4 decomposition at 600°C with a catalytic lifetime exceeding 1,000 hours. 27Al and 71Ga magic-angle spinning nuclear magnetic resonance spectroscopy (MAS NMR) showed that the introduced Ga exists as tetracoordinated Ga sites (GaIV), which readily dissociate water to form Ga-OH. In-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and density function theory (DFT) calculations confirmed that Ga-OH assists the defluorination of poisoned Al active sites via a dehydration-like process. As a result, the Ga/Al2O3 catalyst achieved 100% CF4 decomposition keeping an ultra-long catalytic lifetime and outperforming reported results. This work proposes a new approach for efficient and long-term CF4 decomposition by promoting the regeneration of active sites.