Enhancing the Proportion of Three-coordinated Al Active Sites on Co/Al2O3 for Efficient CF4 Decomposition

Abstract

Aluminum (Al) based catalysts are the most widely used materials for CF4 Catalytic hydrolysis, where three-coordinated Al (AlIII) active sites play a pivotal role in C–F bond activation. The limited proportion of AlIII active sites in conventional Al-based catalysts suppresses their catalytic activity, thereby requiring high temperatures to achieve complete CF4 decomposition. In this work, we developed a Co-modified strategy to enhance CF4 hydrolysis performance by increasing the proportion of AlIII active sites. Structure characterization revealed that Co modification significantly raised the proportion of AlIII sites from 2% (pure Al2O3) to 13%. Temperature-programmed desorption (TPD) analysis showed that the 0.1Co/Al2O3 catalyst exhibits a CF4 adsorption capacity that is 2.0 times higher than that of unmodified Al2O3. Furthermore, in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) detected a 2 cm–1 red shift in the characteristic C–F bond peaks on 0.1Co/Al2O3 catalyst, indicating enhanced C–F bond activation. As a result, 0.1Co/Al2O3 catalyst achieved 100% CF4 decomposition at 580 °C for over 170 hours, significantly outperforming pure Al2O3 (58% and 20 hours). This work opens up a new approach for developing highly efficient catalysts for CF4 hydrolysis at low temperatures.